Regards,
Arun Saravanan
-----Original Message-----
From: Guenter Roeck <groeck7@xxxxxxxxx> On Behalf Of Guenter Roeck
Sent: Wednesday, August 25, 2021 2:25 AM
To: Balac, Arun Saravanan
Cc: jdelvare@xxxxxxxx; linux-hwmon@xxxxxxxxxxxxxxx
Subject: Re: [PATCH v3] hwmon: Add Maxim MAX6620 hardware monitoring driver
[EXTERNAL EMAIL]
On Tue, Aug 24, 2021 at 11:59:26AM +0000, Balac, Arun Saravanan wrote:
From: Arun Saravanan Balachandran <Arun_Saravanan_Balac@xxxxxxxx>
Add hardware monitoring driver for Maxim MAX6620 Fan controller
Originally-from: L. Grunenberg <contact@xxxxxxxxxxxxxx>
Originally-from: Cumulus Networks <support@xxxxxxxxxxxxxxxxxxx>
Originally-from: Shuotian Cheng <shuche@xxxxxxxxxxxxx>
Signed-off-by: Arun Saravanan Balachandran <Arun_Saravanan_Balac@xxxxxxxx>
---
<Formletter>
Changelog:
- Include '<linux/bits.h>'.
- Use BIT() macro in 'max6620_fan_div_from_reg'.
- Define functions 'max6620_fan_rpm_to_tach' , 'max6620_fan_tach_to_rpm'
for RPM to tach conversion and vice versa.
- Drop 'reg' variable and use only variable 'ret' for validation and use of value
returned by i2c_smbus_read_byte_data in 'max6620_update_device'.
- Remove unnecessary enclosing parentheses.
</Formletter>
<Formletter> and </Formletter> were intended to show that the text in between
was auto-generated, not supposed to be includes in the actual change log.
Documentation/hwmon/max6620.rst | 46 +++
Needs to be added to Documentation/hwmon/index.rst
drivers/hwmon/Kconfig | 10 +
drivers/hwmon/Makefile | 1 +
drivers/hwmon/max6620.c | 507 ++++++++++++++++++++++++++++++++
4 files changed, 564 insertions(+)
create mode 100644 Documentation/hwmon/max6620.rst
create mode 100644 drivers/hwmon/max6620.c
base-commit: ff1176468d368232b684f75e82563369208bc371
diff --git a/Documentation/hwmon/max6620.rst b/Documentation/hwmon/max6620.rst
new file mode 100644
index 000000000000..84c1c44d3de4
--- /dev/null
+++ b/Documentation/hwmon/max6620.rst
@@ -0,0 +1,46 @@
+.. SPDX-License-Identifier: GPL-2.0-or-later
+
+Kernel driver max6620
+=====================
+
+Supported chips:
+
+ Maxim MAX6620
+
+ Prefix: 'max6620'
+
+ Addresses scanned: none
+
+ Datasheet: https://urldefense.com/v3/__http://pdfserv.maxim-ic.com/en/ds/MAX6620.pdf__;!!LpKI!2F_9PYXKGKcU2EVLtM4q-fFP1VkDADkUBkRoeet8KfrP1t3jVCOVDCdzlkNKQYKmHwK5UQ$ [pdfserv[.]maxim-ic[.]com]
+
+Authors:
+ - L\. Grunenberg <contact@xxxxxxxxxxxxxx>
+ - Cumulus Networks <support@xxxxxxxxxxxxxxxxxxx>
+ - Shuotian Cheng <shuche@xxxxxxxxxxxxx>
+ - Arun Saravanan Balachandran <Arun_Saravanan_Balac@xxxxxxxx>
+
+Description
+-----------
+
+This driver implements support for Maxim MAX6620 fan controller.
+
+The driver configures the fan controller in RPM mode. To give the readings more
+range or accuracy, the desired value can be set by a programmable register
+(1, 2, 4, 8, 16 or 32). Set higher values for larger speeds.
+
+The driver provides the following sensor access in sysfs:
+
+================ ======= =====================================================
+fan[1-4]_alarm ro Fan alarm.
+fan[1-4]_div rw Sets the nominal RPM range of the fan. Valid values
+ are 1, 2, 4, 8, 16 and 32.
+fan[1-4]_input ro Fan speed in RPM.
+fan[1-4]_target rw Desired fan speed in RPM.
+================ ======= =====================================================
+
+Usage notes
+-----------
+
+This driver does not auto-detect devices. You will have to instantiate the
+devices explicitly. Please see Documentation/i2c/instantiating-devices.rst for
+details.
diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index e3675377bc5d..74811fbaa266 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -1022,6 +1022,16 @@ config SENSORS_MAX31730
This driver can also be built as a module. If so, the module
will be called max31730.
+config SENSORS_MAX6620
+ tristate "Maxim MAX6620 fan controller"
+ depends on I2C
+ help
+ If you say yes here you get support for the MAX6620
+ fan controller.
+
+ This driver can also be built as a module. If so, the module
+ will be called max6620.
+
config SENSORS_MAX6621
tristate "Maxim MAX6621 sensor chip"
depends on I2C
diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
index d712c61c1f5e..9e50ff903931 100644
--- a/drivers/hwmon/Makefile
+++ b/drivers/hwmon/Makefile
@@ -135,6 +135,7 @@ obj-$(CONFIG_SENSORS_MAX1668) += max1668.o
obj-$(CONFIG_SENSORS_MAX197) += max197.o
obj-$(CONFIG_SENSORS_MAX31722) += max31722.o
obj-$(CONFIG_SENSORS_MAX31730) += max31730.o
+obj-$(CONFIG_SENSORS_MAX6620) += max6620.o
obj-$(CONFIG_SENSORS_MAX6621) += max6621.o
obj-$(CONFIG_SENSORS_MAX6639) += max6639.o
obj-$(CONFIG_SENSORS_MAX6642) += max6642.o
diff --git a/drivers/hwmon/max6620.c b/drivers/hwmon/max6620.c
new file mode 100644
index 000000000000..af2301ac9513
--- /dev/null
+++ b/drivers/hwmon/max6620.c
@@ -0,0 +1,507 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Hardware monitoring driver for Maxim MAX6620
+ *
+ * (C) 2012 by L. Grunenberg <contact@xxxxxxxxxxxxxx>
Is this intentional, or was it supposed to be 2021 ?
+ *
+ * based on code written by :
+ * 2007 by Hans J. Koch <hjk@xxxxxxxxxxxx>
+ * John Morris <john.morris@xxxxxxxxxxxxxx>
+ * Copyright (c) 2003 Spirent Communications
+ * and Claus Gindhart <claus.gindhart@xxxxxxxxxxx>
+ *
+ * This module has only been tested with the MAX6620 chip.
+ *
+ * The datasheet was last seen at:
+ *
+ * https://urldefense.com/v3/__http://pdfserv.maxim-ic.com/en/ds/MAX6620.pdf__;!!LpKI!2F_9PYXKGKcU2EVLtM4q-fFP1VkDADkUBkRoeet8KfrP1t3jVCOVDCdzlkNKQYKmHwK5UQ$ [pdfserv[.]maxim-ic[.]com]
+ *
+ */
+
+#include <linux/bits.h>
+#include <linux/err.h>
+#include <linux/hwmon.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/jiffies.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+
+/*
+ * MAX 6620 registers
+ */
+
+#define MAX6620_REG_CONFIG 0x00
+#define MAX6620_REG_FAULT 0x01
+#define MAX6620_REG_CONF_FAN0 0x02
+#define MAX6620_REG_CONF_FAN1 0x03
+#define MAX6620_REG_CONF_FAN2 0x04
+#define MAX6620_REG_CONF_FAN3 0x05
+#define MAX6620_REG_DYN_FAN0 0x06
+#define MAX6620_REG_DYN_FAN1 0x07
+#define MAX6620_REG_DYN_FAN2 0x08
+#define MAX6620_REG_DYN_FAN3 0x09
+#define MAX6620_REG_TACH0 0x10
+#define MAX6620_REG_TACH1 0x12
+#define MAX6620_REG_TACH2 0x14
+#define MAX6620_REG_TACH3 0x16
+#define MAX6620_REG_VOLT0 0x18
+#define MAX6620_REG_VOLT1 0x1A
+#define MAX6620_REG_VOLT2 0x1C
+#define MAX6620_REG_VOLT3 0x1E
+#define MAX6620_REG_TAR0 0x20
+#define MAX6620_REG_TAR1 0x22
+#define MAX6620_REG_TAR2 0x24
+#define MAX6620_REG_TAR3 0x26
+#define MAX6620_REG_DAC0 0x28
+#define MAX6620_REG_DAC1 0x2A
+#define MAX6620_REG_DAC2 0x2C
+#define MAX6620_REG_DAC3 0x2E
+
+/*
+ * Config register bits
+ */
+
+#define MAX6620_CFG_RUN BIT(7)
+#define MAX6620_CFG_POR BIT(6)
+#define MAX6620_CFG_TIMEOUT BIT(5)
+#define MAX6620_CFG_FULLFAN BIT(4)
+#define MAX6620_CFG_OSC BIT(3)
+#define MAX6620_CFG_WD_MASK (BIT(2) | BIT(1))
+#define MAX6620_CFG_WD_2 BIT(1)
+#define MAX6620_CFG_WD_6 BIT(2)
+#define MAX6620_CFG_WD10 (BIT(2) | BIT(1))
+#define MAX6620_CFG_WD BIT(0)
+
+/*
+ * Failure status register bits
+ */
+
+#define MAX6620_FAIL_TACH0 BIT(4)
+#define MAX6620_FAIL_TACH1 BIT(5)
+#define MAX6620_FAIL_TACH2 BIT(6)
+#define MAX6620_FAIL_TACH3 BIT(7)
+#define MAX6620_FAIL_MASK0 BIT(0)
+#define MAX6620_FAIL_MASK1 BIT(1)
+#define MAX6620_FAIL_MASK2 BIT(2)
+#define MAX6620_FAIL_MASK3 BIT(3)
+
+#define MAX6620_CLOCK_FREQ 8192 /* Clock frequency in Hz */
+#define MAX6620_PULSE_PER_REV 2 /* Tachometer pulses per revolution */
+
+/* Minimum and maximum values of the FAN-RPM */
+#define FAN_RPM_MIN 240
+#define FAN_RPM_MAX 30000
+
+static const u8 config_reg[] = {
+ MAX6620_REG_CONF_FAN0,
+ MAX6620_REG_CONF_FAN1,
+ MAX6620_REG_CONF_FAN2,
+ MAX6620_REG_CONF_FAN3,
+};
+
+static const u8 dyn_reg[] = {
+ MAX6620_REG_DYN_FAN0,
+ MAX6620_REG_DYN_FAN1,
+ MAX6620_REG_DYN_FAN2,
+ MAX6620_REG_DYN_FAN3,
+};
+
+static const u8 tach_reg[] = {
+ MAX6620_REG_TACH0,
+ MAX6620_REG_TACH1,
+ MAX6620_REG_TACH2,
+ MAX6620_REG_TACH3,
+};
+
+static const u8 target_reg[] = {
+ MAX6620_REG_TAR0,
+ MAX6620_REG_TAR1,
+ MAX6620_REG_TAR2,
+ MAX6620_REG_TAR3,
+};
+
+/*
+ * Client data (each client gets its own)
+ */
+
+struct max6620_data {
+ struct i2c_client *client;
+ struct mutex update_lock;
+ bool valid; /* false until following fields are valid */
+ unsigned long last_updated; /* in jiffies */
+
+ /* register values */
+ u8 fancfg[4];
+ u8 fandyn[4];
+ u8 fault;
+ u16 tach[4];
+ u16 target[4];
+};
+
+static u8 max6620_fan_div_from_reg(u8 val)
+{
+ return BIT((val & 0xE0) >> 5);
+}
+
+static u16 max6620_fan_rpm_to_tach(u8 div, int rpm)
+{
+ return (60 * div * MAX6620_CLOCK_FREQ) / (rpm * MAX6620_PULSE_PER_REV);
+}
+
+static int max6620_fan_tach_to_rpm(u8 div, u16 tach)
+{
+ return (60 * div * MAX6620_CLOCK_FREQ) / (tach * MAX6620_PULSE_PER_REV);
+}
+
+static int max6620_update_device(struct device *dev)
+{
+ struct max6620_data *data = dev_get_drvdata(dev);
+ struct i2c_client *client = data->client;
+ int i;
+ int ret = 0;
+
+ mutex_lock(&data->update_lock);
+
+ if (time_after(jiffies, data->last_updated + HZ) || !data->valid) {
+ for (i = 0; i < 4; i++) {
+ ret = i2c_smbus_read_byte_data(client, config_reg[i]);
+ if (ret < 0)
+ goto error;
+ data->fancfg[i] = ret;
+
+ ret = i2c_smbus_read_byte_data(client, dyn_reg[i]);
+ if (ret < 0)
+ goto error;
+ data->fandyn[i] = ret;
+
+ ret = i2c_smbus_read_byte_data(client, tach_reg[i]);
+ if (ret < 0)
+ goto error;
+ data->tach[i] = (ret << 3) & 0x7f8;
+ ret = i2c_smbus_read_byte_data(client, tach_reg[i] + 1);
+ if (ret < 0)
+ goto error;
+ data->tach[i] |= (ret >> 5) & 0x7;
+
+ ret = i2c_smbus_read_byte_data(client, target_reg[i]);
+ if (ret < 0)
+ goto error;
+ data->target[i] = (ret << 3) & 0x7f8;
+ ret = i2c_smbus_read_byte_data(client, target_reg[i] + 1);
+ if (ret < 0)
+ goto error;
+ data->target[i] |= (ret >> 5) & 0x7;
+ }
+
+ /*
+ * Alarms are cleared on read in case the condition that
+ * caused the alarm is removed. Keep the value latched here
+ * for providing the register through different alarm files.
+ */
+ ret = i2c_smbus_read_byte_data(client, MAX6620_REG_FAULT);
+ if (ret < 0)
+ goto error;
+ data->fault |= (ret >> 4) & (ret & 0x0F);
+
+ data->last_updated = jiffies;
+ data->valid = true;
+ }
+
+error:
+ mutex_unlock(&data->update_lock);
+ return ret;
+}
+
+static umode_t
+max6620_is_visible(const void *data, enum hwmon_sensor_types type, u32 attr,
+ int channel)
+{
+ switch (type) {
+ case hwmon_fan:
+ switch (attr) {
+ case hwmon_fan_alarm:
+ case hwmon_fan_input:
+ return 0444;
+ case hwmon_fan_div:
+ case hwmon_fan_target:
+ return 0644;
+ default:
+ break;
+ }
+
+ default:
+ break;
+ }
+
+ return 0;
+}
+
+static int
+max6620_read(struct device *dev, enum hwmon_sensor_types type, u32 attr,
+ int channel, long *val)
+{
+ struct max6620_data *data;
+ struct i2c_client *client;
+ int ret = 0;
Unnecessary initialization.
+ u8 div;
+ u8 val1;
+ u8 val2;
+
+ ret = max6620_update_device(dev);
+ if (ret < 0)
+ return ret;
+ data = dev_get_drvdata(dev);
+ client = data->client;
It might be easier to assign those above, with the variable declaration,
but that is just a suggestion.
+
+ switch (type) {
+ case hwmon_fan:
+ switch (attr) {
+ case hwmon_fan_alarm:
+ *val = !!(data->fault & BIT(channel));
+
+ /* Setting TACH count to re-enable fan fault detection */
+ if (*val == 1) {
+ val1 = (data->target[channel] >> 3) & 0xff;
+ val2 = (data->target[channel] << 5) & 0xe0;
+ ret = i2c_smbus_write_byte_data(client,
+ target_reg[channel], val1);
+ if (ret < 0)
+ return ret;
+ ret = i2c_smbus_write_byte_data(client,
+ target_reg[channel] + 1, val2);
+ if (ret < 0)
+ return ret;
+
+ mutex_lock(&data->update_lock);
+ data->fault &= ~BIT(channel);
+ mutex_unlock(&data->update_lock);
The lock needs to be extended across the write operations above and the
assignment to *val. Otherwise multiple read operations in parallel could
create random return values.
+ }
+
+ break;
+ case hwmon_fan_div:
+ *val = max6620_fan_div_from_reg(data->fandyn[channel]);
+ break;
+ case hwmon_fan_input:
+ if (data->tach[channel] == 0) {
+ *val = 0;
+ } else {
+ div = max6620_fan_div_from_reg(data->fandyn[channel]);
+ *val = max6620_fan_tach_to_rpm(div, data->tach[channel]);
+ }
+ break;
+ case hwmon_fan_target:
+ if (data->target[channel] == 0) {
+ *val = 0;
+ } else {
+ div = max6620_fan_div_from_reg(data->fandyn[channel]);
+ *val = max6620_fan_tach_to_rpm(div, data->target[channel]);
+ }
+ break;
+ default:
+ return -EOPNOTSUPP;
+ }
+ break;
+
+ default:
+ return -EOPNOTSUPP;
+ }
+
+ return 0;
+}
+
+static int
+max6620_write(struct device *dev, enum hwmon_sensor_types type, u32 attr,
+ int channel, long val)
+{
+ struct max6620_data *data;
+ struct i2c_client *client;
+ int ret = 0;
Unnecessary initialization.
+ u8 div;
+ u16 tach;
+ u8 val1;
+ u8 val2;
+
+ ret = max6620_update_device(dev);
+ if (ret < 0)
+ return ret;
+ data = dev_get_drvdata(dev);
+ client = data->client;
As above.
+ mutex_lock(&data->update_lock);
+
+ switch (type) {
+ case hwmon_fan:
+ switch (attr) {
+ case hwmon_fan_div:
+ switch (val) {
+ case 1:
+ div = 0;
+ break;
+ case 2:
+ div = 1;
+ break;
+ case 4:
+ div = 2;
+ break;
+ case 8:
+ div = 3;
+ break;
+ case 16:
+ div = 4;
+ break;
+ case 32:
+ div = 5;
+ break;
+ default:
+ ret = -EINVAL;
+ goto error;
+ }
+ data->fandyn[channel] &= 0x1F;
+ data->fandyn[channel] |= div << 5;
+ ret = i2c_smbus_write_byte_data(client, dyn_reg[channel],
+ data->fandyn[channel]);
+ break;
+ case hwmon_fan_target:
+ val = clamp_val(val, FAN_RPM_MIN, FAN_RPM_MAX);
+ div = max6620_fan_div_from_reg(data->fandyn[channel]);
+ tach = max6620_fan_rpm_to_tach(div, val);
+ val1 = (tach >> 3) & 0xff;
+ val2 = (tach << 5) & 0xe0;
+ ret = i2c_smbus_write_byte_data(client, target_reg[channel], val1);
+ if (ret < 0)
+ break;
+ ret = i2c_smbus_write_byte_data(client, target_reg[channel] + 1, val2);
+ if (ret < 0)
+ break;
+
+ /* Setting TACH count re-enables fan fault detection */
+ data->fault &= ~BIT(channel);
+
+ break;
+ default:
+ ret = -EOPNOTSUPP;
+ break;
+ }
+ break;
+
+ default:
+ ret = -EOPNOTSUPP;
+ break;
+ }
+
+error:
+ mutex_unlock(&data->update_lock);
+ return ret;
+}
+
+static const struct hwmon_channel_info *max6620_info[] = {
+ HWMON_CHANNEL_INFO(fan,
+ HWMON_F_INPUT | HWMON_F_DIV | HWMON_F_TARGET | HWMON_F_ALARM,
+ HWMON_F_INPUT | HWMON_F_DIV | HWMON_F_TARGET | HWMON_F_ALARM,
+ HWMON_F_INPUT | HWMON_F_DIV | HWMON_F_TARGET | HWMON_F_ALARM,
+ HWMON_F_INPUT | HWMON_F_DIV | HWMON_F_TARGET | HWMON_F_ALARM),
+ NULL
+};
+
+static const struct hwmon_ops max6620_hwmon_ops = {
+ .read = max6620_read,
+ .write = max6620_write,
+ .is_visible = max6620_is_visible,
+};
+
+static const struct hwmon_chip_info max6620_chip_info = {
+ .ops = &max6620_hwmon_ops,
+ .info = max6620_info,
+};
+
+static int max6620_init_client(struct max6620_data *data)
+{
+ struct i2c_client *client = data->client;
+ int config;
+ int err;
+ int i;
+ int reg;
+
+ config = i2c_smbus_read_byte_data(client, MAX6620_REG_CONFIG);
+ if (config < 0) {
+ dev_err(&client->dev, "Error reading config, aborting.\n");
+ return config;
+ }
+
+ /*
+ * Set bit 4, disable other fans from going full speed on a fail
+ * failure.
+ */
+ err = i2c_smbus_write_byte_data(client, MAX6620_REG_CONFIG, config | 0x10);
+ if (err < 0) {
+ dev_err(&client->dev, "Config write error, aborting.\n");
+ return err;
+ }
+
+ for (i = 0; i < 4; i++) {
+ reg = i2c_smbus_read_byte_data(client, config_reg[i]);
+ if (reg < 0)
+ return reg;
+ data->fancfg[i] = reg;
+
+ /* Enable RPM mode */
+ data->fancfg[i] |= 0xa8;
+ err = i2c_smbus_write_byte_data(client, config_reg[i], data->fancfg[i]);
+ if (err < 0)
+ return err;
+
+ /* 2 counts (001) and Rate change 100 (0.125 secs) */
+ data->fandyn[i] = 0x30;
+ err = i2c_smbus_write_byte_data(client, dyn_reg[i], data->fandyn[i]);
+ if (err < 0)
+ return err;
+ }
+ return 0;
+}
+
+static int max6620_probe(struct i2c_client *client)
+{
+ struct device *dev = &client->dev;
+ struct max6620_data *data;
+ struct device *hwmon_dev;
+ int err;
+
+ data = devm_kzalloc(dev, sizeof(struct max6620_data), GFP_KERNEL);
+ if (!data)
+ return -ENOMEM;
+
+ data->client = client;
+ mutex_init(&data->update_lock);
+
+ err = max6620_init_client(data);
+ if (err)
+ return err;
+
+ hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name,
+ data,
+ &max6620_chip_info,
+ NULL);
+
+ return PTR_ERR_OR_ZERO(hwmon_dev);
+}
+
+static const struct i2c_device_id max6620_id[] = {
+ { "max6620", 0 },
+ { }
+};
+MODULE_DEVICE_TABLE(i2c, max6620_id);
+
+static struct i2c_driver max6620_driver = {
+ .class = I2C_CLASS_HWMON,
+ .driver = {
+ .name = "max6620",
+ },
+ .probe_new = max6620_probe,
+ .id_table = max6620_id,
+};
+
+module_i2c_driver(max6620_driver);
+
+MODULE_AUTHOR("Lucas Grunenberg");
+MODULE_DESCRIPTION("MAX6620 sensor driver");
+MODULE_LICENSE("GPL");
