Re: [PATCH/RFC 2/4] hwmon: PMBus device driver

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On Tue, Jun 29, 2010 at 09:40:59AM -0400, Jonathan Cameron wrote:
> On 06/28/10 22:56, Guenter Roeck wrote:
> Hi Guenter,
> 
> A few questions and inital comments...
> Ouch the pmbus spec is tricky to follow!

Hi Jonathan,

Definitely agree here. And no register is mandatory, making it really difficult 
to write a generic driver.

Comments inline. And thanks a lot for your time!

Guenter

> 
> > Signed-off-by: Guenter Roeck <guenter.roeck@xxxxxxxxxxxx>
> > ---
> >  drivers/hwmon/Kconfig  |   12 +
> >  drivers/hwmon/Makefile |    1 +
> >  drivers/hwmon/pmbus.c  | 1227 ++++++++++++++++++++++++++++++++++++++++++++++++
> >  drivers/hwmon/pmbus.h  |  209 ++++++++
> >  4 files changed, 1449 insertions(+), 0 deletions(-)
> >  create mode 100644 drivers/hwmon/pmbus.c
> >  create mode 100644 drivers/hwmon/pmbus.h
> >
> > diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
> > index e19cf8e..8d53cf7 100644
> > --- a/drivers/hwmon/Kconfig
> > +++ b/drivers/hwmon/Kconfig
> > @@ -702,6 +702,18 @@ config SENSORS_PCF8591
> >         These devices are hard to detect and rarely found on mainstream
> >         hardware.  If unsure, say N.
> >
> > +config SENSORS_PMBUS
> > +     tristate "PMBus devices"
> > +     depends on I2C && EXPERIMENTAL
> > +     default n
> > +     help
> > +       If you say yes here you get hardware monitoring support for various
> > +       PMBus devices, including but not limited to BMR45x, LTC2978, MAX16064,
> > +       MAX8688, and UCD92xx.
> > +
> > +       This driver can also be built as a module. If so, the module will
> > +       be called pmbus.
> > +
> >  config SENSORS_SHT15
> >       tristate "Sensiron humidity and temperature sensors. SHT15 and compat."
> >       depends on GENERIC_GPIO
> > diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
> > index 2138ceb..88b043e 100644
> > --- a/drivers/hwmon/Makefile
> > +++ b/drivers/hwmon/Makefile
> > @@ -83,6 +83,7 @@ obj-$(CONFIG_SENSORS_MC13783_ADC)+= mc13783-adc.o
> >  obj-$(CONFIG_SENSORS_PC87360)        += pc87360.o
> >  obj-$(CONFIG_SENSORS_PC87427)        += pc87427.o
> >  obj-$(CONFIG_SENSORS_PCF8591)        += pcf8591.o
> > +obj-$(CONFIG_SENSORS_PMBUS)  += pmbus.o
> >  obj-$(CONFIG_SENSORS_S3C)    += s3c-hwmon.o
> >  obj-$(CONFIG_SENSORS_SHT15)  += sht15.o
> >  obj-$(CONFIG_SENSORS_SIS5595)        += sis5595.o
> > diff --git a/drivers/hwmon/pmbus.c b/drivers/hwmon/pmbus.c
> > new file mode 100644
> > index 0000000..418ee2c
> > --- /dev/null
> > +++ b/drivers/hwmon/pmbus.c
> > @@ -0,0 +1,1227 @@
> > +/*
> > + * Hardware monitoring driver for PMBus devices
> > + *
> > + * Copyright (C) 2010 Ericsson AB.
> > + *
> > + * This program is free software; you can redistribute it and/or modify
> > + * it under the terms of the GNU General Public License as published by
> > + * the Free Software Foundation; either version 2 of the License, or
> > + * (at your option) any later version.
> > + *
> > + * This program is distributed in the hope that it will be useful,
> > + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> > + * GNU General Public License for more details.
> > + *
> > + * You should have received a copy of the GNU General Public License
> > + * along with this program; if not, write to the Free Software
> > + * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
> > + */
> > +
> > +#include <linux/kernel.h>
> > +#include <linux/module.h>
> > +#include <linux/init.h>
> > +#include <linux/err.h>
> > +#include <linux/slab.h>
> > +#include <linux/i2c.h>
> > +#include <linux/hwmon.h>
> > +#include <linux/hwmon-sysfs.h>
> > +#include <linux/delay.h>
> > +#include "pmbus.h"
> > +
> > +#define PMBUS_SENSORS        64
> > +#define PMBUS_BOOLEANS       64
> > +#define PMBUS_LABELS 32
> > +#define PMBUS_NUM_ATTR       (PMBUS_BOOLEANS + PMBUS_SENSORS + PMBUS_LABELS)
> > +#define PMBUS_PAGES  8
> > +
> > +static int pages;
> > +module_param(pages, int, 0);
> > +MODULE_PARM_DESC(pages, "Number of sensor pages");
> Why is this a module parameter?  If you do it like this
> you will be overriding page count for all devices in the system.
> Is that the intent?
> 
It isn't the intent, really. I want to be able to support more than one page for
a not explicitly supported device. I know using a module parameter is is less than
optimal, and has the problem that it affects all PMBus devices in the system. 

If you have a better idea how to solve this, let me know. I'll add it to the list
of open issues.

> > +
> > +enum chips { ltc2978, max16064, max8688, pmbus, ucd9220, ucd9240 };
> > +
> > +enum pmbus_sensor_classes {
> > +     PSC_VOLTAGE = 0,
> > +     PSC_TEMPERATURE,
> > +     PSC_CURRENT,
> > +     PSC_POWER,
> 
> Perhaps name this PSC_MAX_LABEL or similar to indicate it is just here to
> allow the number of possible classes to be established.

ok.

> > +     SENSOR_CLASSES
> > +};
> > +
> > +struct pmbus_config {
> > +     int pages;              /* Total number of pages (= output sensors) */
> > +     bool direct;            /* true if device uses direct data format */
> > +     /*
> > +      * Support one set of coefficients for each sensor type
> > +      * Used for chips providing data in direct mode.
> > +      */
> > +     int m[SENSOR_CLASSES];  /* mantissa for direct data format */
> > +     int b[SENSOR_CLASSES];  /* offset */
> > +     int R[SENSOR_CLASSES];  /* exponent */
> > +};
> > +
> Can we name these something to do with PB to cut down on chance of name
> clashes.

ok.

> > +#define HAVE_STATUS_VOUT     (1<<0)
> > +#define HAVE_STATUS_IOUT     (1<<1)
> > +#define HAVE_STATUS_INPUT    (1<<2)
> > +#define HAVE_STATUS_TEMP     (1<<3)
> > +
> > +#define PB_STATUS_BASE               0
> > +#define PB_STATUS_VOUT_BASE  (PB_STATUS_BASE + PMBUS_PAGES)
> > +#define PB_STATUS_IOUT_BASE  (PB_STATUS_VOUT_BASE + PMBUS_PAGES)
> > +#define PB_STATUS_INPUT_BASE (PB_STATUS_IOUT_BASE + PMBUS_PAGES)
> > +#define PB_STATUS_TEMP_BASE  (PB_STATUS_INPUT_BASE + 1)
> > +
> > +struct pmbus_sensor {
> > +     char name[I2C_NAME_SIZE];       /* sysfs sensor name */
> > +     u8 page;                        /* page number */
> > +     u8 reg;                         /* register */
> > +     enum pmbus_sensor_classes class;/* sensor class */
> > +     bool update;                    /* runtime sensor update needed */
> > +};
> > +
> What are the next two for?
> > +struct pmbus_boolean {
> > +     char name[I2C_NAME_SIZE];       /* sysfs boolean name */
> > +};
Provides storage for the sysfs name of a boolean. I could have used
a straight variable name here; only reason to use a struct was for consistency.

This stores, for example, "in1_alarm".

> > +
> > +struct pmbus_label {
> > +     char name[I2C_NAME_SIZE];       /* sysfs label name */
> > +     char label[I2C_NAME_SIZE];      /* label */
> > +};

Storage for labels: sysfs name and label name reported by the sysfs entry.
Content would, for example, be 
	.name = "in1_label"
	.label = "vin"

> > +
> > +struct pmbus_data {
> > +     struct device *hwmon_dev;
> > +     enum chips type;
> > +
> > +     bool direct;
> > +     int pages;
> > +
> > +     /* Coefficients, for chips providing data in direct mode  */
> > +     int m[SENSOR_CLASSES];  /* mantissa for direct data format */
> > +     int b[SENSOR_CLASSES];  /* offset */
> > +     int R[SENSOR_CLASSES];  /* exponent */
> > +
> Any chance of getting rid of one of the following? The 'attributes'
> array is must an array of pointers to elements within sensor_devices_attributes.
> It would prevent easy usage of sysfs_create_group so maybe it is better
> to just have the redunancy here.

The variables reflect the static structures used in other hwmon drivers.
I'll have a closer look, but right now I don't really know if/how
I can get rid of it.

> 
> > +     struct sensor_device_attribute
> > +       sensor_device_attributes[PMBUS_NUM_ATTR];
> > +     struct attribute *attributes[PMBUS_NUM_ATTR];
> > +     int num_attributes;
> > +     struct attribute_group group;
> > +
> > +     int num_sensors;
> > +     struct pmbus_sensor sensors[PMBUS_SENSORS];
> > +     int num_booleans;
> > +     struct pmbus_boolean booleans[PMBUS_BOOLEANS];
> > +     int num_labels;
> Can you comment on what these labels are for?

The labels map the non-descriptive default labels (eg "in1") to PMBus names,
e.g. "vin" or "vout". This would not be absolutely necessary, but I think
it helps users to better understand what is returned. Sensors output looks
much better with the labels in place.

> > +     struct pmbus_label labels[PMBUS_LABELS];
> > +
> > +     struct mutex update_lock;
> > +     bool valid;
> > +     unsigned long last_updated;     /* in jiffies */
> > +     u8 status_bits;
> 
> What is the theoretical maximum number of pages?
> Is it the 8 you have above?  A quick look at the rev 1 spec
> suggests 0-1F so 32.  That is going to make for some big
> arrays of fixed size whatever the chip in question needs.
> 
Theoretically it would be 32, per the spec. I decided to use 8,
but that is just an arbitrary limit. If we want to support more, 
I'll definitely have to come up with a scheme to always support 
a dynamic number of attributes (32 pages times 3 sensors times
up to 8 attributes per sensor is a bit much for static allocation).

Reminds me ... there is also the problem of phases, in addition to pages. 
A chip can support multiple phases per page. So maybe it _would_ be
a good idea to make all allocations dynamic.

> Could you do some further grouping into suitable structures?
> Perhaps put sensor_data in the pmbus_sensor struct?
> Can status also be moved into such a struct?  I'm a little
> unclear how it is assocated with the various sensors inputs?
> 
> After such grouping, perhaps the allocation can be made dynamic.

I'll try.

> > +     /*
> > +      * status, status_vout, status_iout are paged.
> > +      * status_input and status_temp are unpaged.
> > +      */
> > +     u8 status[PMBUS_PAGES * 3 + 2];
> > +     u16 sensor_data[PMBUS_SENSORS];
> > +
> > +     u8 currpage;
> > +};
> > +
> 
> Do these need to be complete or do only some devices support direct mode
> reads?

Typically it is either direct mode or linear mode, but not both.
The specification permits for a device to support both, but that
is not the case with either of the device datasheets I looked at.
So we only need to specify m/b/R for devices requiring direct mode.

Even if a device would support both, we would probably want to use
linear mode to avoid having to specify m/b/R.

> > +static const struct pmbus_config pmbus_config[] = {
> > +     [pmbus] = {
> > +             .pages = 1,
> > +             },
> > +     [ltc2978] = {
> > +             .pages = 8,
> > +             },
> > +     [max16064] = {
> > +             .pages = 4,
> > +             .direct = true,
> > +             .m[PSC_VOLTAGE] = 19995,
> > +             .b[PSC_VOLTAGE] = 0,
> > +             .R[PSC_VOLTAGE] = -1,
> > +             .m[PSC_TEMPERATURE] = -7612,
> > +             .b[PSC_TEMPERATURE] = 335,
> > +             .R[PSC_TEMPERATURE] = -3,
> > +             },
> > +     [max8688] = {
> > +             .pages = 1,
> > +             .direct = true,
> > +             .m[PSC_VOLTAGE] = 19995,
> > +             .b[PSC_VOLTAGE] = 0,
> > +             .R[PSC_VOLTAGE] = -1,
> > +             .m[PSC_TEMPERATURE] = -7612,
> > +             .b[PSC_TEMPERATURE] = 335,
> > +             .R[PSC_TEMPERATURE] = -3,
> > +             .m[PSC_CURRENT] = 23109,
> > +             .b[PSC_CURRENT] = 0,
> > +             .R[PSC_CURRENT] = -2,
> > +             },
> > +     [ucd9220] = {
> > +             .pages = 2,
> > +             },
> > +     [ucd9240] = {
> > +             .pages = 4,
> > +             },
> > +};
> > +
> > +static int pmbus_set_page(struct i2c_client *client, u8 page)
> > +{
> > +     struct pmbus_data *data = i2c_get_clientdata(client);
> > +     int rv = 0;
> > +
> > +     if (page != data->currpage) {
> > +             rv = i2c_smbus_write_byte_data(client, PMBUS_PAGE, page);
> > +             data->currpage = page;
> > +     }
> > +     return rv;
> > +}
> > +
> > +static int pmbus_write_byte(struct i2c_client *client, u8 page, u8 value)
> > +{
> > +     if (pmbus_set_page(client, page) < 0)
> > +             return -1;
> > +
> > +     return i2c_smbus_write_byte(client, value);
> > +}
> > +
> > +static int pmbus_write_word_data(struct i2c_client *client, u8 page, u8 reg,
> > +                              u16 word)
> > +{
> > +     if (pmbus_set_page(client, page) < 0)
> > +             return -1;
> > +
> > +     return i2c_smbus_write_word_data(client, reg, word);
> > +}
> > +
> > +static int pmbus_read_word_data(struct i2c_client *client, u8 page, u8 reg)
> > +{
> > +     if (pmbus_set_page(client, page) < 0)
> > +             return -1;
> > +
> > +     return i2c_smbus_read_word_data(client, reg);
> > +}
> > +
> > +static int pmbus_read_byte_data(struct i2c_client *client, u8 page, u8 reg)
> > +{
> > +     if (pmbus_set_page(client, page) < 0)
> > +             return -1;
> > +
> > +     return i2c_smbus_read_byte_data(client, reg);
> > +}
> > +
> > +static void pmbus_clear_faults(struct i2c_client *client)
> > +{
> > +     struct pmbus_data *data = i2c_get_clientdata(client);
> > +     int i;
> > +
> > +     for (i = 0; i < data->pages; i++)
> > +             pmbus_write_byte(client, i, PMBUS_CLEAR_FAULTS);
> > +}
> > +
> > +static bool pmbus_check_byte_register(struct i2c_client *client, int page,
> > +                                   int reg)
> > +{
> Roll everything into one line.
> 
ok.

> return (pmbus_read_byte_data(client, page, reg) >= 0);
> > +     int rv;
> > +
> > +     rv = pmbus_read_byte_data(client, page, reg);
> > +     return (rv >= 0);
> > +}
> > +
> > +static bool pmbus_check_word_register(struct i2c_client *client, int page,
> > +                                   int reg)
> > +{
> Another one liner.

ok.

> > +     int rv;
> > +
> > +     rv = pmbus_read_word_data(client, page, reg);
> > +     return (rv >= 0);
> > +}
> > +
> > +static struct pmbus_data *pmbus_update_device(struct device *dev)
> > +{
> > +     struct i2c_client *client = to_i2c_client(dev);
> > +     struct pmbus_data *data = i2c_get_clientdata(client);
> > +     struct pmbus_data *ret = data;
> > +
> > +     mutex_lock(&data->update_lock);
> > +     if (time_after(jiffies, data->last_updated + HZ) || !data->valid) {
> > +             int i, val;
> > +
> > +             for (i = 0; i < data->pages; i++) {
> > +                     val = pmbus_read_byte_data(client, i,
> > +                                                PMBUS_STATUS_BYTE);
> > +                     if (val < 0) {
> > +                             ret = ERR_PTR(val);
> > +                             goto abort;
> > +                     }
> > +                     data->status[PB_STATUS_BASE + i] = val;
> > +             }
> > +             if (data->status_bits & HAVE_STATUS_VOUT)
> > +                     for (i = 0; i < data->pages; i++) {
> > +                             val = pmbus_read_byte_data(client, i,
> > +                                                        PMBUS_STATUS_VOUT);
> > +                             if (val < 0) {
> > +                                     ret = ERR_PTR(val);
> > +                                     goto abort;
> > +                             }
> > +                             data->status[PB_STATUS_VOUT_BASE + i] = val;
> > +                     }
> > +             if (data->status_bits & HAVE_STATUS_IOUT)
> > +                     for (i = 0; i < data->pages; i++) {
> > +                             val = pmbus_read_byte_data(client, i,
> > +                                                        PMBUS_STATUS_IOUT);
> > +                             if (val < 0) {
> > +                                     ret = ERR_PTR(val);
> > +                                     goto abort;
> > +                             }
> > +                             data->status[PB_STATUS_IOUT_BASE + i] = val;
> > +                     }
> > +             if (data->status_bits & HAVE_STATUS_INPUT) {
> > +                     val = pmbus_read_byte_data(client, 0,
> > +                                                PMBUS_STATUS_INPUT);
> > +                     if (val < 0) {
> > +                             ret = ERR_PTR(val);
> > +                             goto abort;
> > +                     }
> > +                     data->status[PB_STATUS_INPUT_BASE] = val;
> > +             }
> > +             if (data->status_bits & HAVE_STATUS_TEMP) {
> > +                     val = pmbus_read_byte_data(client, 0,
> > +                                                PMBUS_STATUS_TEMPERATURE);
> > +                     if (val < 0) {
> > +                             ret = ERR_PTR(val);
> > +                             goto abort;
> > +                     }
> > +                     data->status[PB_STATUS_TEMP_BASE] = val;
> > +             }
> > +             for (i = 0; i < data->num_sensors; i++) {
> > +                     struct pmbus_sensor *sensor = &data->sensors[i];
> > +
> > +                     if (!data->valid || sensor->update) {
> > +                             val = pmbus_read_word_data(client, sensor->page,
> > +                                                        sensor->reg);
> > +                             if (val < 0) {
> > +                                     ret = ERR_PTR(val);
> > +                                     goto abort;
> > +                             }
> > +                             data->sensor_data[i] = val;
> > +                     }
> > +             }
> > +             pmbus_clear_faults(client);
> > +             data->last_updated = jiffies;
> > +             data->valid = 1;
> > +     }
> > +abort:
> > +     mutex_unlock(&data->update_lock);
> > +     return ret;
> > +}
> > +
> > +/*
> > + * Convert linear sensor values to milli- or micro-units
> > + * depending on sensor type.
> > + */
> > +static long pmbus_reg2data_linear(struct pmbus_data *data,
> > +                               enum pmbus_sensor_classes class, u16 adc)
> > +{
> > +     s16 exponent, mantissa;
> > +     long val;
> > +
> > +     exponent = adc >> 11;
> > +     mantissa = adc & 0x07ff;
> > +
> > +     if (exponent > 0x0f)
> > +             exponent |= 0xffe0;     /* sign extend exponent */
> > +     if (mantissa > 0x03ff)
> > +             mantissa |= 0xf800;     /* sign extend mantissa */
> > +
> > +     /* scale result to milli-units */
> > +     val = mantissa * 1000L;
> > +
> > +     /* scale result to micro-units for power sensors */
> > +     if (class == PSC_POWER)
> > +             val = val * 1000L;
> > +
> > +     if (exponent > 0)
> > +             val <<= exponent;
> Don't need this check...
> val >>= 0 is same as val.

Good point.

> > +     else if (exponent < 0)
> > +             val >>= -exponent;
> > +
> > +     return val;
> > +}
> > +
> > +/*
> > + * Convert direct sensor values to milli- or micro-units
> > + * depending on sensor type.
> > + */
> > +static long pmbus_reg2data_direct(struct pmbus_data *data,
> > +                               enum pmbus_sensor_classes class, u16 adc)
> > +{
> > +     long val = (s16) adc;
> > +     long m, b, R;
> > +
> > +     m = data->m[class];
> > +     b = data->b[class];
> > +     R = data->R[class];
> > +
> > +     if (m == 0)
> > +             return 0;
> > +
> > +     /* X = 1/m * (Y * 10^-R - b) */
> > +     R = -R + 3;             /* scale result to milli-units */
> > +     b *= 1000;              /* subtract milli-units */
> > +
> > +     /* scale result to micro-units for power sensors */
> > +     if (class == PSC_POWER) {
> > +             R += 3;
> > +             b *= 1000;
> > +     }
> > +
> > +     while (R > 0) {
> > +             val *= 10;
> > +             R--;
> > +     }
> > +     while (R < 0) {
> > +             val = DIV_ROUND_CLOSEST(val, 10);
> > +             R++;
> > +     }
> > +
> > +     return (val - b) / m;
> > +}
> > +
> > +static long pmbus_reg2data(struct pmbus_data *data,
> > +                        enum pmbus_sensor_classes class, u16 adc)
> > +{
> > +     long val;
> > +
> > +     if (data->direct)
> > +             val = pmbus_reg2data_direct(data, class, adc);
> > +     else
> > +             val = pmbus_reg2data_linear(data, class, adc);
> > +
> > +     return val;
> > +}
> > +
> > +#define MAX_MANTISSA    (1023 * 1000)
> > +#define MIN_MANTISSA    (511 * 1000)
> > +
> > +static u16 pmbus_data2reg_linear(struct pmbus_data *data,
> > +                              enum pmbus_sensor_classes class, long val)
> > +{
> > +     s16 exponent = 0, mantissa = 0;
> > +     bool negative = false;
> > +
> > +     /* simple case */
> > +     if (val == 0)
> > +             return 0;
> > +
> > +     if (val < 0) {
> > +             negative = true;
> > +             val = -val;
> > +     }
> > +
> > +     /* Power is in uW. Convert to mW before converting. */
> > +     if (class == PSC_POWER)
> > +             val = DIV_ROUND_CLOSEST(val, 1000L);
> > +
> > +     /* Reduce large mantissa until it fits into 10 bit */
> > +     while (val >= MAX_MANTISSA && exponent < 15) {
> > +             exponent++;
> > +             val >>= 1;
> > +     }
> > +     /* Increase small mantissa to improve precision */
> > +     while (val < MIN_MANTISSA && exponent > -15) {
> > +             exponent--;
> > +             val <<= 1;
> > +     }
> > +
> > +     /* Convert mantissa from milli-units to units */
> > +     mantissa = DIV_ROUND_CLOSEST(val, 1000);
> > +
> > +     /* Ensure that resulting number is within range */
> > +     if (mantissa > 0x3ff)
> > +             mantissa = 0x3ff;
> > +
> > +     /* restore sign */
> > +     if (negative)
> > +             mantissa = -mantissa;
> > +
> > +     /* Convert to 5 bit exponent, 11 bit mantissa */
> > +     return (mantissa & 0x7ff) | ((exponent << 11) & 0xf800);
> > +}
> > +
> > +static u16 pmbus_data2reg_direct(struct pmbus_data *data,
> > +                              enum pmbus_sensor_classes class, long val)
> > +{
> > +     long m, b, R;
> > +
> > +     m = data->m[class];
> > +     b = data->b[class];
> > +     R = data->R[class];
> > +
> > +     /* Power is in uW. Adjust R. */
> > +     if (class == PSC_POWER)
> > +             R -= 3;
> > +
> > +     /* Calculate Y = (m * X + b) * 10^R */
> > +     R -= 3;         /* Adjust R for data in milli-units */
> > +     val *= m;
> > +     val += b * 1000;
> > +
> > +     while (R > 0) {
> > +             val *= 10;
> > +             R--;
> > +     }
> > +     while (R < 0) {
> > +             val = DIV_ROUND_CLOSEST(val, 10);
> > +             R++;
> > +     }
> > +
> > +     return val;
> > +}
> > +
> > +static u16 pmbus_data2reg(struct pmbus_data *data,
> > +                       enum pmbus_sensor_classes class, long val)
> > +{
> > +     u16 reg;
> > +
> > +     if (data->direct)
> > +             reg = pmbus_data2reg_direct(data, class, val);
> > +     else
> > +             reg = pmbus_data2reg_linear(data, class, val);
> > +
> > +     return reg;
> > +}
> > +
> > +/* Return converted value from given object */
> > +static long pmbus_get_sensor(struct pmbus_data *data, int index)
> > +{
> > +     return pmbus_reg2data(data, data->sensors[index].class,
> > +                           data->sensor_data[index]);
> > +}
> > +
> > +/*
> > + * Return boolean calculated from converted data.
> > + * <index> defines a status register index and mask, and optionally
> > + * two sensor indexes.
> > + * The upper half-word references the two sensors,
> > + * the lower half word references status register and mask.
> > + * The function returns true if (status[reg] & mask) is true and,
> > + * if specified, if v1 >= v2.
> > + * To determine if an object exceeds upper limits, specify <v, limit>.
> > + * To determine if an object exceeds lower limits, specify <limit, v>.
> > + */
> > +static long pmbus_get_boolean(struct pmbus_data *data, int index)
> > +{
> > +     u8 s1 = (index >> 24) & 0xff;
> > +     u8 s2 = (index >> 16) & 0xff;
> > +     u8 reg = (index >> 8) & 0xff;
> > +     u8 mask = index & 0xff;
> > +     int rv = 0;
> > +     u8 regval = data->status[reg] & mask;
> > +
> > +     if (!s1 && !s2)
> > +             rv = !!regval;
> > +     else {
> > +             int v1, v2;
> > +
> > +             v1 = pmbus_reg2data(data, data->sensors[s1].class,
> > +                                 data->sensor_data[s1]);
> > +             v2 = pmbus_reg2data(data, data->sensors[s2].class,
> > +                                 data->sensor_data[s2]);
> > +             rv = !!(regval && v1 >= v2);
> > +     }
> > +     return rv;
> > +}
> > +
> > +#define PMBUS_SHOW_INT(what) \
> > +     static ssize_t pmbus_show_##what(struct device *dev, \
> > +                                      struct device_attribute *da, \
> > +                                      char *buf) \
> > +{ \
> > +     struct sensor_device_attribute *attr = to_sensor_dev_attr(da); \
> > +     struct pmbus_data *data = pmbus_update_device(dev); \
> > +     long val; \
> > +     if (IS_ERR(data)) \
> > +             return PTR_ERR(data); \
> > +     val = pmbus_get_##what(data, attr->index); \
> > +     return snprintf(buf, PAGE_SIZE, "%ld\n", val); \
> > +}
> > +
> > +PMBUS_SHOW_INT(sensor);
> > +PMBUS_SHOW_INT(boolean);
> > +
> > +static ssize_t pmbus_set_sensor(struct device *dev,
> > +                             struct device_attribute *devattr,
> > +                             const char *buf, size_t count)
> > +{
> > +     struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
> > +     struct i2c_client *client = to_i2c_client(dev);
> > +     struct pmbus_data *data = i2c_get_clientdata(client);
> > +     struct pmbus_sensor *sensor = &data->sensors[attr->index];
> > +     ssize_t rv = count;
> > +     long val = 0;
> > +     int ret;
> > +     u16 reg;
> > +
> > +     if (strict_strtol(buf, 10, &val) < 0)
> > +             return -EINVAL;
> > +
> > +     mutex_lock(&data->update_lock);
> > +     reg = pmbus_data2reg(data, sensor->class, val);
> > +     ret = pmbus_write_word_data(client, sensor->page, sensor->reg, reg);
> > +     if (ret < 0)
> > +             rv = ret;
> > +     else
> > +             data->sensor_data[attr->index] = reg;
> > +     mutex_unlock(&data->update_lock);
> > +     return rv;
> > +}
> > +
> > +static ssize_t pmbus_show_label(struct device *dev,
> > +                             struct device_attribute *da,
> > +                             char *buf)
> > +{
> > +     struct i2c_client *client = to_i2c_client(dev);
> > +     struct pmbus_data *data = i2c_get_clientdata(client);
> > +     struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
> > +
> > +     return snprintf(buf, PAGE_SIZE, "%s\n",
> > +                     data->labels[attr->index].label);
> > +}
> > +
> > +#define PMBUS_ADD_ATTR(data, _name, _idx, _mode, _show, _set)                \
> > +do {                                                                 \
> > +     struct sensor_device_attribute *a                               \
> > +             = &data->sensor_device_attributes[data->num_attributes];\
> > +     BUG_ON(data->num_attributes >=PMBUS_NUM_ATTR);                  \
> > +     a->dev_attr.attr.name = _name;                                  \
> > +     a->dev_attr.attr.mode = _mode;                                  \
> > +     a->dev_attr.show = _show;                                       \
> > +     a->dev_attr.store = _set;                                       \
> > +     a->index = _idx;                                                \
> > +     data->attributes[data->num_attributes] = &a->dev_attr.attr;     \
> > +     data->num_attributes++;                                         \
> > +} while (0)
> > +
> > +#define PMBUS_ADD_GET_ATTR(data, _name, _type, _idx)                 \
> > +     PMBUS_ADD_ATTR(data, _name, _idx, S_IRUGO,                      \
> > +                    pmbus_show_##_type,  NULL)
> > +
> > +#define PMBUS_ADD_SET_ATTR(data, _name, _type, _idx)                 \
> > +     PMBUS_ADD_ATTR(data, _name, _idx, S_IWUSR | S_IRUGO,            \
> > +                    pmbus_show_##_type, pmbus_set_##_type)
> > +
> > +static void pmbus_add_boolean(struct pmbus_data *data,
> > +                           const char *name, const char *type, int seq,
> > +                           int val)
> > +{
> > +     struct pmbus_boolean *boolean;
> > +
> > +     BUG_ON(data->num_booleans >= PMBUS_BOOLEANS);
> > +
> > +     boolean = &data->booleans[data->num_booleans];
> > +
> > +     snprintf(boolean->name, sizeof(boolean->name), "%s%d_%s",
> > +              name, seq, type);
> > +     PMBUS_ADD_GET_ATTR(data, boolean->name, boolean, val);
> > +     data->num_booleans++;
> > +}
> > +
> > +static void pmbus_add_boolean_reg(struct pmbus_data *data,
> > +                               const char *name, const char *type,
> > +                               int seq, int reg, int bit)
> > +{
> > +     pmbus_add_boolean(data, name, type, seq,
> > +                       (reg << 8) | bit);
> > +}
> > +
> > +static void pmbus_add_boolean_cmp(struct pmbus_data *data,
> > +                               const char *name, const char *type,
> > +                               int seq, int i1, int i2, int reg,
> > +                               int mask)
> > +{
> > +       pmbus_add_boolean(data, name, type, seq,
> > +                      (i1 << 24) | (i2 << 16) | (reg << 8) | mask);
> > +}
> > +
> > +static void pmbus_add_sensor(struct pmbus_data *data,
> > +                          const char *name, const char *type, int seq,
> > +                          int page, int reg, enum pmbus_sensor_classes class,
> > +                          bool update)
> > +{
> > +     struct pmbus_sensor *sensor;
> > +
> > +     BUG_ON(data->num_sensors >= PMBUS_SENSORS);
> > +
> > +     sensor = &data->sensors[data->num_sensors];
> > +     snprintf(sensor->name, sizeof(sensor->name), "%s%d_%s",
> > +              name, seq, type);
> > +     sensor->page = page;
> > +     sensor->reg = reg;
> > +     sensor->class = class;
> > +     sensor->update = update;
> > +     if (update)
> > +             PMBUS_ADD_GET_ATTR(data, sensor->name, sensor,
> > +                                data->num_sensors);
> > +     else
> > +             PMBUS_ADD_SET_ATTR(data, sensor->name, sensor,
> > +                                data->num_sensors);
> > +     data->num_sensors++;
> > +}
> > +
> > +static void pmbus_add_label(struct pmbus_data *data,
> > +                         const char *name, int seq,
> > +                         const char *lstring, int index)
> > +{
> > +     struct pmbus_label *label;
> > +
> > +     BUG_ON(data->num_labels >= PMBUS_LABELS);
> > +
> > +     label = &data->labels[data->num_labels];
> > +     snprintf(label->name, sizeof(label->name), "%s%d_label",
> > +              name, seq);
> > +     if (!index)
> > +             strncpy(label->label, lstring, sizeof(label->label) - 1);
> > +     else
> > +             snprintf(label->label, sizeof(label->label), "%s%d", lstring,
> > +                      index);
> > +
> > +     PMBUS_ADD_GET_ATTR(data, label->name, label, data->num_labels);
> > +     data->num_labels++;
> > +}
> > +
> > +static int pmbus_temp_sensors[] = {
> > +     PMBUS_READ_TEMPERATURE_1,
> > +     PMBUS_READ_TEMPERATURE_2,
> > +     PMBUS_READ_TEMPERATURE_3
> > +};
> > +
> > +static int pmbus_probe(struct i2c_client *client,
> > +                    const struct i2c_device_id *id)
> > +{
> > +     struct pmbus_data *data;
> > +     int i, in_index, ret;
> > +     int i0, i1;
> > +
> > +     if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_BYTE_DATA
> > +                                  | I2C_FUNC_SMBUS_WORD_DATA))
> > +             return -ENODEV;
> > +
> This is an odd way of doing this.  Assign ret only if (!data) rather
> than here.

Ok.

> > +     ret = -ENOMEM;
> > +     data = kzalloc(sizeof(*data), GFP_KERNEL);
> > +     if (!data)
> > +             goto out;
> > +
> > +     i2c_set_clientdata(client, data);
> > +     mutex_init(&data->update_lock);
> > +
> Why not use the name rather than the id?

No special reason. Consider it changed.

> > +     dev_dbg(&client->dev, "PMBus device type %d", (int)id->driver_data);
> > +
> > +     data->type = id->driver_data;
> 
> Perhaps neater to put a pointer directly to pmbus_config in pmbus_data
> structure and use that?

See below.

> > +     data->direct = pmbus_config[data->type].direct;
> > +     data->pages = pmbus_config[data->type].pages;
> Please justify this parameter (may be elsewhere!) as I'm unconvinced it is
> a good idea when you may well have multiple pmbus devices in a system?

I agree. I'll have to find a better solution to specify the number of pages 
for a not explicitly supported chip.

> > +     if (pages > 0)
> > +             data->pages = pages;
> > +
> Again, if one just has a pointer to the pmbus_config hten no need to copy
> these across.

There is a PMBus command to read the coefficients (PMBUS_COEFFICIENTS).
I did not implement it, since it is not supported by any of the chips I looked at.
Reason for copying the data from config was to keep the path open to using
that command. Or, in other words, the copied values can be dynamic for not
explicitly supported chips.

Thinking about it, maybe I should implement reading the coefficients from the chip
(after all, I can simulate it) and fill "direct" and m/b/R from the command's return values.
Any thoughts ?

> > +     if (data->direct)
> > +             for (i = 0; i < SENSOR_CLASSES; i++) {
> > +                     data->m[i] = pmbus_config[data->type].m[i];
> > +                     data->b[i] = pmbus_config[data->type].b[i];
> > +                     data->R[i] = pmbus_config[data->type].R[i];
> > +             }
> > +
> > +     if (data->type == pmbus) {
> > +             /*
> > +              * We could try to determine supported options here.
> > +              * However, it appears that hardly any chips support
> > +              * the CAPABILITY, QUERY, or COEFFICIENTS commands.
> > +              * Thus, we just use default basic settings.
> > +              */
> > +     }
> > +
> > +     /*
> > +      * Bail out if the number of pages is bad, or if more than
> > +      * one page was configured and the chip has no PAGE register.
> > +      */
>   I think you only need to run this if you have the pages module parameter
> specified (or there is a bug in your driver / someone is lying about what
> is wired up, neither of which should be explicitly handled)

Yes, I know. Call it defensive programming. I don't mind taking it out, but 
then it doesn't hurt and I would prefer to keep it in.

> > +     if (data->pages > PMBUS_PAGES ||
> > +         (data->pages > 1 && !pmbus_check_byte_register(client, 0,
> > +                                                        PMBUS_PAGE))) {
> > +             dev_err(&client->dev, "%d pages but no PAGE register",
> > +                     data->pages);
> > +             ret = -EINVAL;
> > +             goto out_data;
> > +     }
> > +
> > +     /*
> > +      * Bail out if status register or PMBus revision register
> > +      * does not exist.
> > +      */
> Again, doesn't this just mean you don't have a pmbus device?  If this driver's
> probe is running you should be sure you have one.

Again, a matter of defensive programming. I would prefer to keep it.

> > +     if (!pmbus_check_byte_register(client, 0, PMBUS_STATUS_BYTE)
> > +         || !pmbus_check_byte_register(client, 0, PMBUS_REVISION)) {
> > +             ret = -ENODEV;
> > +             goto out_data;
> > +     }
> > +
> > +     /*
> > +      * Identify supported status registers
> > +      */
> > +     if (pmbus_check_byte_register(client, 0, PMBUS_STATUS_VOUT))
> > +             data->status_bits |= HAVE_STATUS_VOUT;
> > +     if (pmbus_check_byte_register(client, 0, PMBUS_STATUS_IOUT))
> > +             data->status_bits |= HAVE_STATUS_IOUT;
> > +     if (pmbus_check_byte_register(client, 0, PMBUS_STATUS_INPUT))
> > +             data->status_bits |= HAVE_STATUS_INPUT;
> > +     if (pmbus_check_byte_register(client, 0, PMBUS_STATUS_TEMPERATURE))
> > +             data->status_bits |= HAVE_STATUS_TEMP;
> > +
> > +     /*
> > +      * Input voltage sensors
> > +      */
> > +     in_index = 1;
> > +     if (pmbus_check_word_register(client, 0, PMBUS_READ_VIN)) {
> > +             bool have_fault = false;
> > +
> > +             i0 = data->num_sensors;
> > +             pmbus_add_label(data, "in", in_index, "vin", 0);
> > +             pmbus_add_sensor(data, "in", "input", in_index,
> > +                              0, PMBUS_READ_VIN, PSC_VOLTAGE, true);
> > +             if (pmbus_check_word_register(client, 0,
> > +                                           PMBUS_VIN_UV_WARN_LIMIT)) {
> > +                     i1 = data->num_sensors;
> > +                     pmbus_add_sensor(data, "in", "min", in_index,
> > +                                      0, PMBUS_VIN_UV_WARN_LIMIT,
> > +                                      PSC_VOLTAGE, false);
> > +                     if (data->status_bits & HAVE_STATUS_INPUT)
> > +                             pmbus_add_boolean_reg(data, "in", "min_alarm",
> > +                                                   in_index,
> > +                                                   PB_STATUS_INPUT_BASE,
> > +                                                   PB_VOLTAGE_UV_WARNING);
> > +             }
> > +             if (pmbus_check_word_register(client, 0,
> > +                                           PMBUS_VIN_UV_FAULT_LIMIT)) {
> > +                     i1 = data->num_sensors;
> > +                     pmbus_add_sensor(data, "in", "lcrit", in_index,
> > +                                      0, PMBUS_VIN_UV_FAULT_LIMIT,
> > +                                      PSC_VOLTAGE, false);
> > +                     if (data->status_bits & HAVE_STATUS_INPUT)
> > +                             have_fault = true;
> > +             }
> > +             if (pmbus_check_word_register(client, 0,
> > +                                           PMBUS_VIN_OV_WARN_LIMIT)) {
> > +                     i1 = data->num_sensors;
> > +                     pmbus_add_sensor(data, "in", "max", in_index,
> > +                                      0, PMBUS_VIN_OV_WARN_LIMIT,
> > +                                      PSC_VOLTAGE, false);
> > +                     if (data->status_bits & HAVE_STATUS_INPUT)
> > +                             pmbus_add_boolean_reg(data, "in", "max_alarm",
> > +                                                   in_index,
> > +                                                   PB_STATUS_INPUT_BASE,
> > +                                                   PB_VOLTAGE_OV_WARNING);
> > +             }
> > +             if (pmbus_check_word_register(client, 0,
> > +                                           PMBUS_VIN_OV_FAULT_LIMIT)) {
> > +                     i1 = data->num_sensors;
> > +                     pmbus_add_sensor(data, "in", "crit", in_index,
> > +                                      0, PMBUS_VIN_OV_FAULT_LIMIT,
> > +                                      PSC_VOLTAGE, false);
> > +                     if (data->status_bits & HAVE_STATUS_INPUT)
> > +                             have_fault = true;
> > +             }
> > +             if (have_fault) {
> > +                     pmbus_add_boolean_reg(data, "in", "fault",
> > +                                           in_index,
> > +                                           PB_STATUS_INPUT_BASE,
> > +                                           PB_VOLTAGE_UV_FAULT
> > +                                           | PB_VOLTAGE_OV_FAULT);
> > +             }
> > +             in_index++;
> > +     }
> > +     if (pmbus_check_word_register(client, 0, PMBUS_READ_VCAP)) {
> > +             pmbus_add_label(data, "in", in_index, "vcap", 0);
> > +             pmbus_add_sensor(data, "in", "input", in_index, 0,
> > +                              PMBUS_READ_VCAP, PSC_VOLTAGE, true);
> > +             in_index++;
> > +     }
> > +
> > +     /*
> > +      * Output voltage sensors
> > +      */
> > +     for (i = 0; i < data->pages; i++) {
> > +             bool have_fault = false;
> > +
> > +             if (!pmbus_check_word_register(client, i, PMBUS_READ_VOUT))
> > +                     break;
> > +
> > +             i0 = data->num_sensors;
> > +             pmbus_add_label(data, "in", in_index, "vout", i+1);
> > +             pmbus_add_sensor(data, "in", "input", in_index, i,
> > +                              PMBUS_READ_VOUT, PSC_VOLTAGE, true);
> > +             if (pmbus_check_word_register(client, i,
> > +                                           PMBUS_VOUT_UV_WARN_LIMIT)) {
> > +                     i1 = data->num_sensors;
> > +                     pmbus_add_sensor(data, "in", "min", in_index, i,
> > +                                      PMBUS_VOUT_UV_WARN_LIMIT, PSC_VOLTAGE,
> > +                                      false);
> > +                     if (data->status_bits & HAVE_STATUS_VOUT)
> > +                             pmbus_add_boolean_reg(data, "in", "min_alarm",
> > +                                                   in_index,
> > +                                                   PB_STATUS_VOUT_BASE + i,
> > +                                                   PB_VOLTAGE_UV_WARNING);
> > +             }
> > +             if (pmbus_check_word_register(client, i,
> > +                                           PMBUS_VOUT_UV_FAULT_LIMIT)) {
> > +                     i1 = data->num_sensors;
> > +                     pmbus_add_sensor(data, "in", "lcrit", in_index, i,
> > +                                      PMBUS_VOUT_UV_FAULT_LIMIT, PSC_VOLTAGE,
> > +                                      false);
> > +                     if (data->status_bits & HAVE_STATUS_VOUT)
> > +                             have_fault = true;
> > +             }
> > +             if (pmbus_check_word_register(client, i,
> > +                                           PMBUS_VOUT_OV_WARN_LIMIT)) {
> > +                     i1 = data->num_sensors;
> > +                     pmbus_add_sensor(data, "in", "max", in_index, i,
> > +                                      PMBUS_VOUT_OV_WARN_LIMIT, PSC_VOLTAGE,
> > +                                      false);
> > +                     if (data->status_bits & HAVE_STATUS_VOUT) {
> > +                             pmbus_add_boolean_reg(data, "in", "max_alarm",
> > +                                                   in_index,
> > +                                                   PB_STATUS_VOUT_BASE + i,
> > +                                                   PB_VOLTAGE_OV_WARNING);
> > +                     }
> > +             }
> > +             if (pmbus_check_word_register(client, i,
> > +                                           PMBUS_VOUT_OV_FAULT_LIMIT)) {
> > +                     i1 = data->num_sensors;
> > +                     pmbus_add_sensor(data, "in", "crit", in_index, i,
> > +                                      PMBUS_VOUT_OV_FAULT_LIMIT, PSC_VOLTAGE,
> > +                                      false);
> > +                     if (data->status_bits & HAVE_STATUS_VOUT)
> > +                             have_fault = true;
> > +             }
> > +             if (have_fault) {
> > +                     pmbus_add_boolean_reg(data, "in", "fault",
> > +                                           in_index,
> > +                                           PB_STATUS_VOUT_BASE + i,
> > +                                           PB_VOLTAGE_UV_FAULT
> > +                                           | PB_VOLTAGE_OV_FAULT);
> > +             }
> > +             in_index++;
> > +     }
> > +
> > +     /*
> > +      * Current sensors
> > +      */
> > +
> > +     /*
> > +      * Input current sensors
> > +      */
> > +     in_index = 1;
> > +     if (pmbus_check_word_register(client, 0, PMBUS_READ_IIN)) {
> > +             i0 = data->num_sensors;
> > +             pmbus_add_label(data, "curr", in_index, "iin", 0);
> > +             pmbus_add_sensor(data, "curr", "input", in_index,
> > +                              0, PMBUS_READ_IIN, PSC_CURRENT, true);
> > +             if (pmbus_check_word_register(client, 0,
> > +                                           PMBUS_IIN_OC_WARN_LIMIT)) {
> > +                     i1 = data->num_sensors;
> > +                     pmbus_add_sensor(data, "curr", "max", in_index,
> > +                                      0, PMBUS_IIN_OC_WARN_LIMIT,
> > +                                      PSC_CURRENT, false);
> > +                     if (data->status_bits & HAVE_STATUS_INPUT) {
> > +                             pmbus_add_boolean_reg(data, "curr", "alarm",
> > +                                                   in_index,
> > +                                                   PB_STATUS_INPUT_BASE,
> > +                                                   PB_IIN_OC_WARNING);
> > +                     }
> > +             }
> > +             if (pmbus_check_word_register(client, 0,
> > +                                           PMBUS_IIN_OC_FAULT_LIMIT)) {
> > +                     i1 = data->num_sensors;
> > +                     pmbus_add_sensor(data, "curr", "crit", in_index,
> > +                                      0, PMBUS_IIN_OC_FAULT_LIMIT,
> > +                                      PSC_CURRENT, false);
> > +                     if (data->status_bits & HAVE_STATUS_INPUT) {
> > +                             pmbus_add_boolean_reg(data, "curr", "fault",
> > +                                                   in_index,
> > +                                                   PB_STATUS_INPUT_BASE,
> > +                                                   PB_IIN_OC_FAULT);
> > +                     }
> > +             }
> > +             in_index++;
> > +     }
> > +
> > +     /*
> > +      * Output Current sensors
> > +      */
> > +     for (i = 0; i < data->pages; i++) {
> > +             bool have_fault = false;
> > +
> > +             if (!pmbus_check_word_register(client, i, PMBUS_READ_IOUT))
> > +                     break;
> > +
> > +             i0 = data->num_sensors;
> > +             pmbus_add_label(data, "curr", in_index, "iout", i+1);
> > +             pmbus_add_sensor(data, "curr", "input", in_index, i,
> > +                              PMBUS_READ_IOUT, PSC_CURRENT, true);
> > +             if (pmbus_check_word_register(client, i,
> > +                                           PMBUS_IOUT_OC_WARN_LIMIT)) {
> > +                     i1 = data->num_sensors;
> > +                     pmbus_add_sensor(data, "curr", "max", in_index, i,
> > +                                      PMBUS_IOUT_OC_WARN_LIMIT, PSC_CURRENT,
> > +                                      false);
> > +                     if (data->status_bits & HAVE_STATUS_IOUT)
> > +                             pmbus_add_boolean_reg(data, "curr", "alarm",
> > +                                                   in_index,
> > +                                                   PB_STATUS_IOUT_BASE + i,
> > +                                                   PB_IOUT_OC_WARNING);
> > +             }
> > +             if (pmbus_check_word_register(client, i,
> > +                                           PMBUS_IOUT_OC_FAULT_LIMIT)) {
> > +                     i1 = data->num_sensors;
> > +                     pmbus_add_sensor(data, "curr", "crit", in_index, i,
> > +                                      PMBUS_IOUT_OC_FAULT_LIMIT, PSC_CURRENT,
> > +                                      false);
> > +                     if (data->status_bits & HAVE_STATUS_IOUT)
> > +                             have_fault = true;
> > +             }
> > +             if (pmbus_check_word_register(client, i,
> > +                                           PMBUS_IOUT_UC_FAULT_LIMIT)) {
> > +                     i1 = data->num_sensors;
> > +                     pmbus_add_sensor(data, "curr", "lcrit", in_index, i,
> > +                                      PMBUS_IOUT_UC_FAULT_LIMIT, PSC_CURRENT,
> > +                                      false);
> > +                     if (data->status_bits & HAVE_STATUS_IOUT)
> > +                             have_fault = true;
> > +             }
> > +             if (have_fault) {
> > +                     pmbus_add_boolean_reg(data, "curr", "fault",
> > +                                           in_index,
> > +                                           PB_STATUS_IOUT_BASE + i,
> > +                                           PB_IOUT_UC_FAULT
> > +                                           | PB_IOUT_OC_FAULT);
> > +             }
> > +             in_index++;
> > +     }
> > +
> > +     /*
> > +      * Power sensors
> > +      */
> > +     /*
> > +      * Input Power sensors
> > +      */
> > +     in_index = 1;
> > +     if (pmbus_check_word_register(client, 0, PMBUS_READ_PIN)) {
> > +             i0 = data->num_sensors;
> > +             pmbus_add_label(data, "power", in_index, "pin", 0);
> > +             pmbus_add_sensor(data, "power", "input", in_index,
> > +                              0, PMBUS_READ_PIN, PSC_POWER, true);
> > +             if (pmbus_check_word_register(client, 0,
> > +                                           PMBUS_PIN_OP_WARN_LIMIT)) {
> > +                     i1 = data->num_sensors;
> > +                     pmbus_add_sensor(data, "power", "max", in_index,
> > +                                      0, PMBUS_PIN_OP_WARN_LIMIT, PSC_POWER,
> > +                                      false);
> > +                     if (data->status_bits & HAVE_STATUS_INPUT)
> > +                             pmbus_add_boolean_reg(data, "power", "alarm",
> > +                                                   in_index,
> > +                                                   PB_STATUS_INPUT_BASE,
> > +                                                   PB_PIN_OP_WARNING);
> > +             }
> > +             in_index++;
> > +     }
> > +
> > +     /*
> > +      * Output Power sensors
> > +      */
> > +     for (i = 0; i < data->pages; i++) {
> > +             bool need_alarm = false;
> > +
> > +             if (!pmbus_check_word_register(client, i, PMBUS_READ_POUT))
> > +                     break;
> > +
> > +             i0 = data->num_sensors;
> > +             pmbus_add_label(data, "power", in_index, "pout", i+1);
> > +             pmbus_add_sensor(data, "power", "input", in_index, i,
> > +                              PMBUS_READ_POUT, PSC_POWER, true);
> > +             /*
> > +              * Per hwmon sysfs API, power_cap is to be used to limit output
> > +              * power.
> > +              * We have two registers related to maximum output power,
> > +              * PMBUS_POUT_MAX and PMBUS_POUT_OP_WARN_LIMIT.
> > +              * PMBUS_POUT_MAX matches the powerX_cap attribute definition.
> > +              * There is no attribute in the API to match
> > +              * PMBUS_POUT_OP_WARN_LIMIT. We use powerX_max for now.
> > +              */
> > +             if (pmbus_check_word_register(client, i, PMBUS_POUT_MAX)) {
> > +                     i1 = data->num_sensors;
> > +                     pmbus_add_sensor(data, "power", "cap", in_index, i,
> > +                                      PMBUS_POUT_MAX, PSC_POWER, false);
> > +                     need_alarm = true;
> > +             }
> > +             if (pmbus_check_word_register(client, i,
> > +                                           PMBUS_POUT_OP_WARN_LIMIT)) {
> > +                     i1 = data->num_sensors;
> > +                     pmbus_add_sensor(data, "power", "max", in_index, i,
> > +                                      PMBUS_POUT_OP_WARN_LIMIT, PSC_POWER,
> > +                                      false);
> > +                     need_alarm = true;
> > +             }
> > +             if (need_alarm && (data->status_bits & HAVE_STATUS_IOUT))
> > +                     pmbus_add_boolean_reg(data, "power", "alarm",
> > +                                           in_index,
> > +                                           PB_STATUS_IOUT_BASE,
> > +                                           PB_POUT_OP_WARNING
> > +                                           | PB_POWER_LIMITING);
> > +
> > +             if (pmbus_check_word_register(client, i,
> > +                                           PMBUS_POUT_OP_FAULT_LIMIT)) {
> > +                     i1 = data->num_sensors;
> > +                     pmbus_add_sensor(data, "power", "crit", in_index, i,
> > +                                      PMBUS_POUT_OP_FAULT_LIMIT, PSC_POWER,
> > +                                      false);
> > +                     if (data->status_bits & HAVE_STATUS_IOUT)
> > +                             pmbus_add_boolean_reg(data, "power", "fault",
> > +                                                   in_index,
> > +                                                   PB_STATUS_IOUT_BASE,
> > +                                                   PB_POUT_OP_FAULT);
> > +             }
> > +             in_index++;
> > +     }
> > +
> > +     /*
> > +      * Temperature sensors
> > +      */
> > +     in_index = 1;
> > +     for (i = 0; i < ARRAY_SIZE(pmbus_temp_sensors); i++) {
> > +             if (!pmbus_check_word_register(client, 0,
> > +                                            pmbus_temp_sensors[i]))
> > +                     break;
> > +
> > +             i0 = data->num_sensors;
> > +             pmbus_add_sensor(data, "temp", "input", in_index, 0,
> > +                              pmbus_temp_sensors[i], PSC_TEMPERATURE, true);
> > +
> > +             /*
> > +              * PMBus provides only one status register for all temperature
> > +              * sensors. Thus, we can not use the status register to
> > +              * determine which of the sensors actually caused an alarm
> > +              * or fault. Always compare the current temperature against
> > +              * the limit registers to determine warning or fault conditions.
> > +              */
> > +             if (pmbus_check_word_register(client, 0, PMBUS_UT_WARN_LIMIT)) {
> > +                     i1 = data->num_sensors;
> > +                     pmbus_add_sensor(data, "temp", "min", in_index, 0,
> > +                                      PMBUS_UT_WARN_LIMIT, PSC_TEMPERATURE,
> > +                                      false);
> > +                     if (data->status_bits & HAVE_STATUS_TEMP)
> > +                             pmbus_add_boolean_cmp(data, "temp", "min_alarm",
> > +                                                   in_index, i1, i0,
> > +                                                   PB_STATUS_TEMP_BASE,
> > +                                                   PB_TEMP_UT_WARNING);
> > +             }
> > +             if (pmbus_check_word_register(client, 0,
> > +                                           PMBUS_UT_FAULT_LIMIT)) {
> > +                     i1 = data->num_sensors;
> > +                     pmbus_add_sensor(data, "temp", "lcrit", in_index, 0,
> > +                                      PMBUS_UT_FAULT_LIMIT, PSC_TEMPERATURE,
> > +                                      false);
> > +             }
> > +             if (pmbus_check_word_register(client, 0, PMBUS_OT_WARN_LIMIT)) {
> > +                     i1 = data->num_sensors;
> > +                     pmbus_add_sensor(data, "temp", "max", in_index, 0,
> > +                                      PMBUS_OT_WARN_LIMIT, PSC_TEMPERATURE,
> > +                                      false);
> > +                     if (data->status_bits & HAVE_STATUS_TEMP)
> > +                             pmbus_add_boolean_cmp(data, "temp", "max_alarm",
> > +                                                   in_index, i0, i1,
> > +                                                   PB_STATUS_TEMP_BASE,
> > +                                                   PB_TEMP_OT_WARNING);
> > +             }
> > +             if (pmbus_check_word_register(client, 0,
> > +                                           PMBUS_OT_FAULT_LIMIT)) {
> > +                     i1 = data->num_sensors;
> > +                     pmbus_add_sensor(data, "temp", "crit", in_index, 0,
> > +                                      PMBUS_OT_FAULT_LIMIT, PSC_TEMPERATURE,
> > +                                      false);
> > +                     if (data->status_bits & HAVE_STATUS_TEMP)
> > +                             pmbus_add_boolean_cmp(data, "temp",
> > +                                                   "crit_alarm",
> > +                                                   in_index, i0, i1,
> > +                                                   PB_STATUS_TEMP_BASE,
> > +                                                   PB_TEMP_OT_FAULT);
> > +             }
> > +             in_index++;
> > +     }
> > +
> > +     pmbus_clear_faults(client);
> > +
> > +     ret = -ENODEV;
> > +     /* Register sysfs hooks */
> > +     data->group.attrs = data->attributes;
> > +     ret = sysfs_create_group(&client->dev.kobj, &data->group);
> > +     if (ret)
> > +             goto out_data;
> > +     data->hwmon_dev = hwmon_device_register(&client->dev);
> > +     if (IS_ERR(data->hwmon_dev)) {
> > +             ret = PTR_ERR(data->hwmon_dev);
> > +             goto out_hwmon_device_register;
> > +     }
> > +     return 0;
> > +out_hwmon_device_register:
> > +     sysfs_remove_group(&client->dev.kobj, &data->group);
> > +out_data:
> > +     kfree(data);
> > +out:
> > +     return ret;
> > +}
> > +
> > +static int pmbus_remove(struct i2c_client *client)
> > +{
> > +     struct pmbus_data *data = i2c_get_clientdata(client);
> > +     hwmon_device_unregister(data->hwmon_dev);
> > +     sysfs_remove_group(&client->dev.kobj, &data->group);
> > +     kfree(data);
> > +     return 0;
> > +}
> > +
> > +static const struct i2c_device_id pmbus_id[] = {
> > +     {"bmr45x", pmbus},
> > +     {"ltc2978", ltc2978},
> > +     {"max16064", max16064},
> > +     {"max8688", max8688},
> > +     {"pmbus", pmbus},
> > +     {"ucd921x", pmbus},
> > +     {"ucd9220", ucd9220},
> > +     {"ucd9240", ucd9240},
> > +     {}
> > +};
> > +
> > +MODULE_DEVICE_TABLE(i2c, pmbus_id);
> > +
> > +/* This is the driver that will be inserted */
> > +static struct i2c_driver pmbus_driver = {
> > +     .driver = {
> > +             .name = "pmbus",
> > +             },
> > +     .probe = pmbus_probe,
> > +     .remove = pmbus_remove,
> > +     .id_table = pmbus_id,
> > +};
> > +
> > +static int __init pmbus_init(void)
> > +{
> > +     return i2c_add_driver(&pmbus_driver);
> > +}
> > +
> > +static void __exit pmbus_exit(void)
> > +{
> > +     i2c_del_driver(&pmbus_driver);
> > +}
> > +
> > +MODULE_AUTHOR("Guenter Roeck");
> > +MODULE_DESCRIPTION("PMBus driver");
> > +MODULE_LICENSE("GPL");
> > +module_init(pmbus_init);
> > +module_exit(pmbus_exit);
> > diff --git a/drivers/hwmon/pmbus.h b/drivers/hwmon/pmbus.h
> > new file mode 100644
> > index 0000000..2a8a027
> > --- /dev/null
> > +++ b/drivers/hwmon/pmbus.h
> > @@ -0,0 +1,209 @@
> > +/*
> > + * pmbus.h - Common defines and structures for PMBus devices
> > + *
> > + * Copyright (c) 2010 Ericsson AB.
> > + *
> > + * This program is free software; you can redistribute it and/or modify
> > + * it under the terms of the GNU General Public License as published by
> > + * the Free Software Foundation; either version 2 of the License, or
> > + * (at your option) any later version.
> > + *
> > + * This program is distributed in the hope that it will be useful,
> > + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> > + * GNU General Public License for more details.
> > + *
> > + * You should have received a copy of the GNU General Public License
> > + * along with this program; if not, write to the Free Software
> > + * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
> > + */
> > +
> > +#ifndef PMBUS_H
> > +#define PMBUS_H
> > +
> > +/*
> > + * Registers
> > + */
> > +#define PMBUS_PAGE                   0x00
> > +#define PMBUS_OPERATION                      0x01
> > +#define PMBUS_ON_OFF_CONFIG          0x02
> > +#define PMBUS_CLEAR_FAULTS           0x03
> > +#define PMBUS_PHASE                  0x04
> > +
> > +#define PMBUS_CAPABILITY             0x19
> > +#define PMBUS_QUERY                  0x1A
> > +
> > +#define PMBUS_VOUT_MODE                      0x20
> > +#define PMBUS_VOUT_COMMAND           0x21
> > +#define PMBUS_VOUT_TRIM                      0x22
> > +#define PMBUS_VOUT_CAL_OFFSET                0x23
> > +#define PMBUS_VOUT_MAX                       0x24
> > +#define PMBUS_VOUT_MARGIN_HIGH               0x25
> > +#define PMBUS_VOUT_MARGIN_LOW                0x26
> > +#define PMBUS_VOUT_TRANSITION_RATE   0x27
> > +#define PMBUS_VOUT_DROOP             0x28
> > +#define PMBUS_VOUT_SCALE_LOOP                0x29
> > +#define PMBUS_VOUT_SCALE_MONITOR     0x2A
> > +
> > +#define PMBUS_COEFFICIENTS           0x30
> > +#define PMBUS_POUT_MAX                       0x31
> > +
> > +#define PMBUS_VOUT_OV_FAULT_LIMIT    0x40
> > +#define PMBUS_VOUT_OV_FAULT_RESPONSE 0x41
> > +#define PMBUS_VOUT_OV_WARN_LIMIT     0x42
> > +#define PMBUS_VOUT_UV_WARN_LIMIT     0x43
> > +#define PMBUS_VOUT_UV_FAULT_LIMIT    0x44
> > +#define PMBUS_VOUT_UV_FAULT_RESPONSE 0x45
> > +#define PMBUS_IOUT_OC_FAULT_LIMIT    0x46
> > +#define PMBUS_IOUT_OC_FAULT_RESPONSE 0x47
> > +#define PMBUS_IOUT_OC_LV_FAULT_LIMIT 0x48
> > +#define PMBUS_IOUT_OC_LV_FAULT_RESPONSE      0x49
> > +#define PMBUS_IOUT_OC_WARN_LIMIT     0x4A
> > +#define PMBUS_IOUT_UC_FAULT_LIMIT    0x4B
> > +#define PMBUS_IOUT_UC_FAULT_RESPONSE 0x4C
> > +
> > +#define PMBUS_OT_FAULT_LIMIT         0x4F
> > +#define PMBUS_OT_FAULT_RESPONSE              0x50
> > +#define PMBUS_OT_WARN_LIMIT          0x51
> > +#define PMBUS_UT_WARN_LIMIT          0x52
> > +#define PMBUS_UT_FAULT_LIMIT         0x53
> > +#define PMBUS_UT_FAULT_RESPONSE              0x54
> > +#define PMBUS_VIN_OV_FAULT_LIMIT     0x55
> > +#define PMBUS_VIN_OV_FAULT_RESPONSE  0x56
> > +#define PMBUS_VIN_OV_WARN_LIMIT              0x57
> > +#define PMBUS_VIN_UV_WARN_LIMIT              0x58
> > +#define PMBUS_VIN_UV_FAULT_LIMIT     0x59
> > +
> > +#define PMBUS_IIN_OC_FAULT_LIMIT     0x5B
> > +#define PMBUS_IIN_OC_WARN_LIMIT              0x5D
> > +
> > +#define PMBUS_POUT_OP_FAULT_LIMIT    0x68
> > +#define PMBUS_POUT_OP_WARN_LIMIT     0x6A
> > +#define PMBUS_PIN_OP_WARN_LIMIT              0x6B
> > +
> > +#define PMBUS_STATUS_BYTE            0x78
> > +#define PMBUS_STATUS_WORD            0x79
> > +#define PMBUS_STATUS_VOUT            0x7A
> > +#define PMBUS_STATUS_IOUT            0x7B
> > +#define PMBUS_STATUS_INPUT           0x7C
> > +#define PMBUS_STATUS_TEMPERATURE     0x7D
> > +#define PMBUS_STATUS_CML             0x7E
> > +#define PMBUS_STATUS_OTHER           0x7F
> > +#define PMBUS_STATUS_MFR_SPECIFIC    0x80
> > +#define PMBUS_STATUS_FANS_1_2                0x81
> > +#define PMBUS_STATUS_FANS_3_4                0x82
> > +
> > +#define PMBUS_READ_VIN                       0x88
> > +#define PMBUS_READ_IIN                       0x89
> > +#define PMBUS_READ_VCAP                      0x8A
> > +#define PMBUS_READ_VOUT                      0x8B
> > +#define PMBUS_READ_IOUT                      0x8C
> > +#define PMBUS_READ_TEMPERATURE_1     0x8D
> > +#define PMBUS_READ_TEMPERATURE_2     0x8E
> > +#define PMBUS_READ_TEMPERATURE_3     0x8F
> > +#define PMBUS_READ_FAN_SPEED_1               0x90
> > +#define PMBUS_READ_FAN_SPEED_2               0x91
> > +#define PMBUS_READ_FAN_SPEED_3               0x92
> > +#define PMBUS_READ_FAN_SPEED_4               0x93
> > +#define PMBUS_READ_DUTY_CYCLE                0x94
> > +#define PMBUS_READ_FREQUENCY         0x95
> > +#define PMBUS_READ_POUT                      0x96
> > +#define PMBUS_READ_PIN                       0x97
> > +
> > +#define PMBUS_REVISION                       0x98
> > +#define PMBUS_MFR_ID                 0x99
> > +#define PMBUS_MFR_MODEL                      0x9A
> > +#define PMBUS_MFR_REVISION           0x9B
> > +#define PMBUS_MFR_LOCATION           0x9C
> > +#define PMBUS_MFR_DATE                       0x9D
> > +#define PMBUS_MFR_SERIAL             0x9E
> > +
> > +#define LTC2978_MFR_SPECIAL_ID               0xE7
> > +
> > +/*
> > + * CAPABILITY
> > + */
> > +#define PB_CAPABILITY_SMBALERT               (1<<4)
> > +#define PB_CAPABILITY_ERROR_CHECK    (1<<7)
> > +
> > +/*
> > + * VOUT_MODE
> > + */
> > +#define PB_VOUT_MODE_MODE_MASK               0xe0
> > +#define PB_VOUT_MODE_PARAM_MASK              0x1f
> > +
> > +#define PB_VOUT_MODE_LINEAR          0x00
> > +#define PB_VOUT_MODE_VID             0x20
> > +#define PB_VOUT_MODE_DIRECT          0x40
> > +
> > +/*
> > + * STATUS_BYTE, STATUS_WORD (lower)
> > + */
> > +#define PB_STATUS_NONE_ABOVE         (1<<0)
> > +#define PB_STATUS_CML                        (1<<1)
> > +#define PB_STATUS_TEMPERATURE                (1<<2)
> > +#define PB_STATUS_VIN_UV             (1<<3)
> > +#define PB_STATUS_IOUT_OC            (1<<4)
> > +#define PB_STATUS_VOUT_OV            (1<<5)
> > +#define PB_STATUS_OFF                        (1<<6)
> > +#define PB_STATUS_BUSY                       (1<<7)
> > +
> > +/*
> > + * STATUS_WORD (upper)
> > + */
> > +#define PB_STATUS_UNKNOWN            (1<<8)
> > +#define PB_STATUS_OTHER                      (1<<9)
> > +#define PB_STATUS_FANS                       (1<<10)
> > +#define PB_STATUS_POWER_GOOD_N               (1<<11)
> > +#define PB_STATUS_WORD_MFR           (1<<12)
> > +#define PB_STATUS_INPUT                      (1<<13)
> > +#define PB_STATUS_IOUT_POUT          (1<<14)
> > +#define PB_STATUS_VOUT                       (1<<15)
> > +
> > +/*
> > + * STATUS_IOUT
> > + */
> > +#define PB_POUT_OP_WARNING           (1<<0)
> > +#define PB_POUT_OP_FAULT             (1<<1)
> > +#define PB_POWER_LIMITING            (1<<2)
> > +#define PB_CURRENT_SHARE_FAULT               (1<<3)
> > +#define PB_IOUT_UC_FAULT             (1<<4)
> > +#define PB_IOUT_OC_WARNING           (1<<5)
> > +#define PB_IOUT_OC_LV_FAULT          (1<<6)
> > +#define PB_IOUT_OC_FAULT             (1<<7)
> > +
> > +/*
> > + * STATUS_VOUT, STATUS_INPUT
> > + */
> > +#define PB_VOLTAGE_UV_FAULT          (1<<4)
> > +#define PB_VOLTAGE_UV_WARNING                (1<<5)
> > +#define PB_VOLTAGE_OV_WARNING                (1<<6)
> > +#define PB_VOLTAGE_OV_FAULT          (1<<7)
> > +
> > +/*
> > + * STATUS_INPUT
> > + */
> > +#define PB_PIN_OP_WARNING            (1<<0)
> > +#define PB_IIN_OC_WARNING            (1<<1)
> > +#define PB_IIN_OC_FAULT                      (1<<2)
> > +
> > +/*
> > + * STATUS_TEMPERATURE
> > + */
> > +#define PB_TEMP_UT_FAULT             (1<<4)
> > +#define PB_TEMP_UT_WARNING           (1<<5)
> > +#define PB_TEMP_OT_WARNING           (1<<6)
> > +#define PB_TEMP_OT_FAULT             (1<<7)
> > +
> > +/*
> > + * CML_FAULT_STATUS
> > + */
> > +#define      PB_CML_FAULT_OTHER_MEM_LOGIC    (1<<0)
> > +#define      PB_CML_FAULT_OTHER_COMM         (1<<1)
> > +#define      PB_CML_FAULT_PROCESSOR          (1<<3)
> > +#define      PB_CML_FAULT_MEMORY             (1<<4)
> > +#define      PB_CML_FAULT_PACKET_ERROR       (1<<5)
> > +#define      PB_CML_FAULT_INVALID_DATA       (1<<6)
> > +#define      PB_CML_FAULT_INVALID_COMMAND    (1<<7)
> > +
> > +#endif /* PB_H */
> 
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