Re: [PATCH v2 3/3] hwmon: ltc2990: support all measurement modes

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On Wed, Jun 28, 2017 at 04:24:03PM +0200, Mike Looijmans wrote:
> On 17-11-16 17:56, Guenter Roeck wrote:
> >On 11/17/2016 04:10 AM, Tom Levens wrote:
> >>Updated version of the ltc2990 driver which supports all measurement
> >>modes available in the chip. The mode can be set through a devicetree
> >>attribute.
> >
> >property
> >
> >>
> >>Signed-off-by: Tom Levens <tom.levens@xxxxxxx>
> >>---
> >>
> >>Changes since v1:
> >>  * Refactored value conversion (patch 1/3)
> >>  * Split the devicetree binding into separate patch (patch 2/3)
> >>  * Specifying an invalid mode now returns -EINVAL, previously this
> >>    only issued a warning and used the default value
> >>  * Removed the "mode" sysfs attribute, as the mode of the chip is
> >>    hardware specific and should not be user configurable. This allows much
> >>    simpler code as a result.
> >>
> >> Documentation/hwmon/ltc2990 |   24 ++++---
> >> drivers/hwmon/Kconfig       |    7 +--
> >> drivers/hwmon/ltc2990.c     |  167 ++++++++++++++++++++++++++++++++++++-------
> >> 3 files changed, 159 insertions(+), 39 deletions(-)
> >>
> >>diff --git a/Documentation/hwmon/ltc2990 b/Documentation/hwmon/ltc2990
> >>index c25211e..3ed68f6 100644
> >>--- a/Documentation/hwmon/ltc2990
> >>+++ b/Documentation/hwmon/ltc2990
> >>@@ -8,6 +8,7 @@ Supported chips:
> >>     Datasheet: http://www.linear.com/product/ltc2990
> >>
> >> Author: Mike Looijmans <mike.looijmans@xxxxxxxx>
> >>+        Tom Levens <tom.levens@xxxxxxx>
> >>
> >>
> >> Description
> >>@@ -16,10 +17,8 @@ Description
> >> LTC2990 is a Quad I2C Voltage, Current and Temperature Monitor.
> >> The chip's inputs can measure 4 voltages, or two inputs together (1+2 and 3+4)
> >> can be combined to measure a differential voltage, which is typically used to
> >>-measure current through a series resistor, or a temperature.
> >>-
> >>-This driver currently uses the 2x differential mode only. In order to support
> >>-other modes, the driver will need to be expanded.
> >>+measure current through a series resistor, or a temperature with an external
> >>+diode.
> >>
> >>
> >> Usage Notes
> >>@@ -32,12 +31,19 @@ devices explicitly.
> >> Sysfs attributes
> >> ----------------
> >>
> >>+in0_input     Voltage at Vcc pin in millivolt (range 2.5V to 5V)
> >>+temp1_input   Internal chip temperature in millidegrees Celcius
> >>+
> >>+A subset of the following attributes are visible, depending on the measurement
> >>+mode of the chip.
> >>+
> >>+in[1-4]_input Voltage at V[1-4] pin in millivolt
> >>+temp2_input   External temperature sensor TR1 in millidegrees Celcius
> >>+temp3_input   External temperature sensor TR2 in millidegrees Celcius
> >>+curr1_input   Current in mA across V1-V2 assuming a 1mOhm sense resistor
> >>+curr2_input   Current in mA across V3-V4 assuming a 1mOhm sense resistor
> >>+
> >> The "curr*_input" measurements actually report the voltage drop across the
> >> input pins in microvolts. This is equivalent to the current through a 1mOhm
> >> sense resistor. Divide the reported value by the actual sense resistor value
> >> in mOhm to get the actual value.
> >>-
> >>-in0_input     Voltage at Vcc pin in millivolt (range 2.5V to 5V)
> >>-temp1_input   Internal chip temperature in millidegrees Celcius
> >>-curr1_input   Current in mA across v1-v2 assuming a 1mOhm sense resistor.
> >>-curr2_input   Current in mA across v3-v4 assuming a 1mOhm sense resistor.
> >>diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
> >>index 45cef3d..f7096ca 100644
> >>--- a/drivers/hwmon/Kconfig
> >>+++ b/drivers/hwmon/Kconfig
> >>@@ -699,15 +699,12 @@ config SENSORS_LTC2945
> >>       be called ltc2945.
> >>
> >> config SENSORS_LTC2990
> >>-    tristate "Linear Technology LTC2990 (current monitoring mode only)"
> >>+    tristate "Linear Technology LTC2990"
> >>     depends on I2C
> >>     help
> >>       If you say yes here you get support for Linear Technology LTC2990
> >>       I2C System Monitor. The LTC2990 supports a combination of voltage,
> >>-      current and temperature monitoring, but in addition to the Vcc supply
> >>-      voltage and chip temperature, this driver currently only supports
> >>-      reading two currents by measuring two differential voltages across
> >>-      series resistors.
> >>+      current and temperature monitoring.
> >>
> >>       This driver can also be built as a module. If so, the module will
> >>       be called ltc2990.
> >>diff --git a/drivers/hwmon/ltc2990.c b/drivers/hwmon/ltc2990.c
> >>index 0ec4102..e8d36f5 100644
> >>--- a/drivers/hwmon/ltc2990.c
> >>+++ b/drivers/hwmon/ltc2990.c
> >>@@ -6,11 +6,7 @@
> >>  *
> >>  * License: GPLv2
> >>  *
> >>- * This driver assumes the chip is wired as a dual current monitor, and
> >>- * reports the voltage drop across two series resistors. It also reports
> >>- * the chip's internal temperature and Vcc power supply voltage.
> >>- *
> >>- * Value conversion refactored
> >>+ * Value conversion refactored and support for all measurement modes added
> >>  * by Tom Levens <tom.levens@xxxxxxx>
> >>  */
> >>
> >>@@ -21,6 +17,7 @@
> >> #include <linux/i2c.h>
> >> #include <linux/kernel.h>
> >> #include <linux/module.h>
> >>+#include <linux/of.h>
> >>
> >> #define LTC2990_STATUS    0x00
> >> #define LTC2990_CONTROL    0x01
> >>@@ -35,32 +32,96 @@
> >> #define LTC2990_CONTROL_KELVIN        BIT(7)
> >> #define LTC2990_CONTROL_SINGLE        BIT(6)
> >> #define LTC2990_CONTROL_MEASURE_ALL    (0x3 << 3)
> >>-#define LTC2990_CONTROL_MODE_CURRENT    0x06
> >>-#define LTC2990_CONTROL_MODE_VOLTAGE    0x07
> >>+#define LTC2990_CONTROL_MODE_DEFAULT    0x06
> >
> >I think LTC2990_CONTROL_MODE_CURRENT was better - it describes the actual mode.
> >Changing the define to _DEFAULT does not really improve code readability.
> >
> >>+#define LTC2990_CONTROL_MODE_MAX    0x07
> >>+
> >>+#define LTC2990_IN0    BIT(0)
> >>+#define LTC2990_IN1    BIT(1)
> >>+#define LTC2990_IN2    BIT(2)
> >>+#define LTC2990_IN3    BIT(3)
> >>+#define LTC2990_IN4    BIT(4)
> >>+#define LTC2990_CURR1    BIT(5)
> >>+#define LTC2990_CURR2    BIT(6)
> >>+#define LTC2990_TEMP1    BIT(7)
> >>+#define LTC2990_TEMP2    BIT(8)
> >>+#define LTC2990_TEMP3    BIT(9)
> >>+
> >>+static const int ltc2990_attrs_ena[] = {
> >>+    LTC2990_IN1 | LTC2990_IN2 | LTC2990_TEMP3,
> >>+    LTC2990_CURR1 | LTC2990_TEMP3,
> >>+    LTC2990_CURR1 | LTC2990_IN3 | LTC2990_IN4,
> >>+    LTC2990_TEMP2 | LTC2990_IN3 | LTC2990_IN4,
> >>+    LTC2990_TEMP2 | LTC2990_CURR2,
> >>+    LTC2990_TEMP2 | LTC2990_TEMP3,
> >>+    LTC2990_CURR1 | LTC2990_CURR2,
> >>+    LTC2990_IN1 | LTC2990_IN2 | LTC2990_IN3 | LTC2990_IN4
> >>+};
> >>+
> >>+struct ltc2990_data {
> >>+    struct i2c_client *i2c;
> >>+    u32 mode;
> >>+};
> >>
> >> /* Return the converted value from the given register in uV or mC */
> >>-static int ltc2990_get_value(struct i2c_client *i2c, u8 reg, s32 *result)
> >>+static int ltc2990_get_value(struct i2c_client *i2c, int index, s32 *result)
> >> {
> >>     s32 val;
> >>+    u8 reg;
> >>+
> >>+    switch (index) {
> >>+    case LTC2990_IN0:
> >>+        reg = LTC2990_VCC_MSB;
> >>+        break;
> >>+    case LTC2990_IN1:
> >>+    case LTC2990_CURR1:
> >>+    case LTC2990_TEMP2:
> >>+        reg = LTC2990_V1_MSB;
> >>+        break;
> >>+    case LTC2990_IN2:
> >>+        reg = LTC2990_V2_MSB;
> >>+        break;
> >>+    case LTC2990_IN3:
> >>+    case LTC2990_CURR2:
> >>+    case LTC2990_TEMP3:
> >>+        reg = LTC2990_V3_MSB;
> >>+        break;
> >>+    case LTC2990_IN4:
> >>+        reg = LTC2990_V4_MSB;
> >>+        break;
> >>+    case LTC2990_TEMP1:
> >>+        reg = LTC2990_TINT_MSB;
> >>+        break;
> >>+    default:
> >>+        return -EINVAL;
> >>+    }
> >>
> >>     val = i2c_smbus_read_word_swapped(i2c, reg);
> >>     if (unlikely(val < 0))
> >>         return val;
> >>
> >>-    switch (reg) {
> >>-    case LTC2990_TINT_MSB:
> >>-        /* internal temp, 0.0625 degrees/LSB, 13-bit  */
> >>+    switch (index) {
> >>+    case LTC2990_TEMP1:
> >>+    case LTC2990_TEMP2:
> >>+    case LTC2990_TEMP3:
> >>+        /* temp, 0.0625 degrees/LSB, 13-bit  */
> >>         *result = sign_extend32(val, 12) * 1000 / 16;
> >>         break;
> >>-    case LTC2990_V1_MSB:
> >>-    case LTC2990_V3_MSB:
> >>-         /* Vx-Vy, 19.42uV/LSB. Depends on mode. */
> >>+    case LTC2990_CURR1:
> >>+    case LTC2990_CURR2:
> >>+         /* Vx-Vy, 19.42uV/LSB */
> >>         *result = sign_extend32(val, 14) * 1942 / 100;
> >>         break;
> >>-    case LTC2990_VCC_MSB:
> >>-        /* Vcc, 305.18μV/LSB, 2.5V offset */
> >>+    case LTC2990_IN0:
> >>+        /* Vcc, 305.18uV/LSB, 2.5V offset */
> >>         *result = sign_extend32(val, 14) * 30518 / (100 * 1000) + 2500;
> >>         break;
> >>+    case LTC2990_IN1:
> >>+    case LTC2990_IN2:
> >>+    case LTC2990_IN3:
> >>+    case LTC2990_IN4:
> >>+        /* Vx: 305.18uV/LSB */
> >>+        *result = sign_extend32(val, 14) * 30518 / (100 * 1000);
> >>+        break;
> >>     default:
> >>         return -EINVAL; /* won't happen, keep compiler happy */
> >>     }
> >>@@ -72,48 +133,104 @@ static ssize_t ltc2990_show_value(struct device *dev,
> >>                   struct device_attribute *da, char *buf)
> >> {
> >>     struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
> >>+    struct ltc2990_data *data = dev_get_drvdata(dev);
> >>     s32 value;
> >>     int ret;
> >>
> >>-    ret = ltc2990_get_value(dev_get_drvdata(dev), attr->index, &value);
> >>+    ret = ltc2990_get_value(data->i2c, attr->index, &value);
> >>     if (unlikely(ret < 0))
> >>         return ret;
> >>
> >>     return snprintf(buf, PAGE_SIZE, "%d\n", value);
> >> }
> >>
> >>+static umode_t ltc2990_attrs_visible(struct kobject *kobj,
> >>+                     struct attribute *a, int n)
> >>+{
> >>+    struct device *dev = container_of(kobj, struct device, kobj);
> >>+    struct ltc2990_data *data = dev_get_drvdata(dev);
> >>+    struct device_attribute *da =
> >>+            container_of(a, struct device_attribute, attr);
> >>+    struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
> >>+
> >>+    if (attr->index == LTC2990_TEMP1 ||
> >>+        attr->index == LTC2990_IN0 ||
> >>+        attr->index & ltc2990_attrs_ena[data->mode])
> >>+        return a->mode;
> >>+    else
> >
> >Unnecessary else
> >
> >>+        return 0;
> >>+}
> >>+
> >> static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, ltc2990_show_value, NULL,
> >>-              LTC2990_TINT_MSB);
> >>+              LTC2990_TEMP1);
> >>+static SENSOR_DEVICE_ATTR(temp2_input, S_IRUGO, ltc2990_show_value, NULL,
> >>+              LTC2990_TEMP2);
> >>+static SENSOR_DEVICE_ATTR(temp3_input, S_IRUGO, ltc2990_show_value, NULL,
> >>+              LTC2990_TEMP3);
> >> static SENSOR_DEVICE_ATTR(curr1_input, S_IRUGO, ltc2990_show_value, NULL,
> >>-              LTC2990_V1_MSB);
> >>+              LTC2990_CURR1);
> >> static SENSOR_DEVICE_ATTR(curr2_input, S_IRUGO, ltc2990_show_value, NULL,
> >>-              LTC2990_V3_MSB);
> >>+              LTC2990_CURR2);
> >> static SENSOR_DEVICE_ATTR(in0_input, S_IRUGO, ltc2990_show_value, NULL,
> >>-              LTC2990_VCC_MSB);
> >>+              LTC2990_IN0);
> >>+static SENSOR_DEVICE_ATTR(in1_input, S_IRUGO, ltc2990_show_value, NULL,
> >>+              LTC2990_IN1);
> >>+static SENSOR_DEVICE_ATTR(in2_input, S_IRUGO, ltc2990_show_value, NULL,
> >>+              LTC2990_IN2);
> >>+static SENSOR_DEVICE_ATTR(in3_input, S_IRUGO, ltc2990_show_value, NULL,
> >>+              LTC2990_IN3);
> >>+static SENSOR_DEVICE_ATTR(in4_input, S_IRUGO, ltc2990_show_value, NULL,
> >>+              LTC2990_IN4);
> >>
> >> static struct attribute *ltc2990_attrs[] = {
> >>     &sensor_dev_attr_temp1_input.dev_attr.attr,
> >>+    &sensor_dev_attr_temp2_input.dev_attr.attr,
> >>+    &sensor_dev_attr_temp3_input.dev_attr.attr,
> >>     &sensor_dev_attr_curr1_input.dev_attr.attr,
> >>     &sensor_dev_attr_curr2_input.dev_attr.attr,
> >>     &sensor_dev_attr_in0_input.dev_attr.attr,
> >>+    &sensor_dev_attr_in1_input.dev_attr.attr,
> >>+    &sensor_dev_attr_in2_input.dev_attr.attr,
> >>+    &sensor_dev_attr_in3_input.dev_attr.attr,
> >>+    &sensor_dev_attr_in4_input.dev_attr.attr,
> >>     NULL,
> >> };
> >>-ATTRIBUTE_GROUPS(ltc2990);
> >>+
> >>+static const struct attribute_group ltc2990_group = {
> >>+    .attrs = ltc2990_attrs,
> >>+    .is_visible = ltc2990_attrs_visible,
> >>+};
> >>+__ATTRIBUTE_GROUPS(ltc2990);
> >>
> >> static int ltc2990_i2c_probe(struct i2c_client *i2c,
> >>                  const struct i2c_device_id *id)
> >> {
> >>     int ret;
> >>     struct device *hwmon_dev;
> >>+    struct ltc2990_data *data;
> >>+    struct device_node *of_node = i2c->dev.of_node;
> >>
> >>     if (!i2c_check_functionality(i2c->adapter, I2C_FUNC_SMBUS_BYTE_DATA |
> >>                      I2C_FUNC_SMBUS_WORD_DATA))
> >>         return -ENODEV;
> >>
> >>-    /* Setup continuous mode, current monitor */
> >>+    data = devm_kzalloc(&i2c->dev, sizeof(struct ltc2990_data), GFP_KERNEL);
> >>+    if (unlikely(!data))
> >>+        return -ENOMEM;
> >>+    data->i2c = i2c;
> >>+
> >>+    if (!of_node || of_property_read_u32(of_node, "lltc,mode", &data->mode))
> >>+        data->mode = LTC2990_CONTROL_MODE_DEFAULT;
> >
> >Iam arguing with myself if we should still do this or if we should read the mode
> >from the chip instead if it isn't provided (after all, it may have been
> >initialized
> >by the BIOS/ROMMON).
> >
> >Mike, would that break your application, or can you specify the mode in
> >devicetree ?
> 
> OMFG, I just spent half the day implementing the exact same thing, and only
> after sumbmitting it, I stumbled upon this thread. I must be getting old.
> 
> A well, seems I implemented things a bit differently, so you get to pick and
> choose which patch was better.
> 

As I just replied to your patch, there is no question here. The compatible
statement refers to chip compatibility; one can not use it to also provide
configuration information.

> Whatever happened to this patch though? It didn't make it to mainline,
> otherwise I'd have found it sooner...
> 
I'll have to look it up, but I guess I didn't get an updated version.

Guenter

> 
> >
> >Thanks,
> >Guenter
> >
> >>+
> >>+    if (data->mode > LTC2990_CONTROL_MODE_MAX) {
> >>+        dev_err(&i2c->dev, "Error: Invalid mode %d.\n", data->mode);
> >>+        return -EINVAL;
> >>+    }
> >>+
> >>+    /* Setup continuous mode */
> >>     ret = i2c_smbus_write_byte_data(i2c, LTC2990_CONTROL,
> >>                     LTC2990_CONTROL_MEASURE_ALL |
> >>-                    LTC2990_CONTROL_MODE_CURRENT);
> >>+                    data->mode);
> >>     if (ret < 0) {
> >>         dev_err(&i2c->dev, "Error: Failed to set control mode.\n");
> >>         return ret;
> >>@@ -127,7 +244,7 @@ static int ltc2990_i2c_probe(struct i2c_client *i2c,
> >>
> >>     hwmon_dev = devm_hwmon_device_register_with_groups(&i2c->dev,
> >>                                i2c->name,
> >>-                               i2c,
> >>+                               data,
> >>                                ltc2990_groups);
> >>
> >>     return PTR_ERR_OR_ZERO(hwmon_dev);
> >>
> >
> 
> 
> 
> Kind regards,
> 
> Mike Looijmans
> System Expert
> 
> TOPIC Products
> Materiaalweg 4, NL-5681 RJ Best
> Postbus 440, NL-5680 AK Best
> Telefoon: +31 (0) 499 33 69 79
> E-mail: mike.looijmans@xxxxxxxxxxxxxxxxx
> Website: www.topicproducts.com
> 
> Please consider the environment before printing this e-mail
> 
> 
> 
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