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Date:   Wed, 12 Jul 2017 00:00:31 +0200
From:   Tom Levens <tom.levens@...n.ch>
To:     Guenter Roeck <linux@...ck-us.net>
CC:     Mike Looijmans <mike.looijmans@...ic.nl>,
        Tom Levens <tom.levens@...n.ch>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        "Jean Delvare" <jdelvare@...e.com>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <linux-hwmon@...r.kernel.org>
Subject: Re: [PATCH v3 3/3] hwmon: ltc2990: support all measurement modes



On Mon, 3 Jul 2017, Guenter Roeck wrote:

> On 07/02/2017 11:29 PM, Mike Looijmans wrote:
>>  Applied, and tested on my board, so you have my
>>
>>  Tested-By: mike.looijmans@...ic.nl
>>
>>  Probably the maintainers will like to see a patch header mail with a "v3"
>>  summary for what you've changed ("git send-email --cover-letter" or
>>  something similar to that)
>> 
>
> ... and without it, the patch series tends to end up at the end of my review
> list since I'll have to spend time tracking down the changes myself or, per
> my choice, start all over and hope I catch all the problems found earlier.
>
> In other words, if people would like their patch series handled with
> priority, making life easy for maintainers is a good start.

Apologies, it seems the change summary got lost when sending the patches. 
Here it is:

Changes since v2:
  * If a devicetree node does not exist, do not initialise the chip. In
    this case it is assumed that the initialisation has been done by
    another source.
  * Allow configuration of both of the "mode" fields in the control
    register.
  * Rename the devicetree property lltc->mode to lltc->meas-mode.
  * Specifying the mode in the devicetree node is now mandatory.
  * Small documentation updates.
  * Revert some unnecessary change of types.

> Guenter
>
>>  On 03-07-17 06:29, Tom Levens wrote:
>> >  Updated version of the ltc2990 driver which supports all measurement
>> >  modes (current, voltage, temperature) available in the chip.
>> > 
>> >  If devicetree is used, the mode must be specified with the property
>> >  "lltc,meas-mode". The format and possible values of the property are
>
> AFAIK, DT maintainers are not much into abbreviations.

As far as I recall, this change was the suggestion of Rob as "mode" was 
too vague.

>> >  described in the binding.
>> > 
>> >  If devicetree is not used, the mode of the chip will not be configured.
>> >  Unless the chip is configured by another source, only the internal
>> >  temperature and supply voltage will be measured.
>> > 
>> >  Signed-off-by: Tom Levens <tom.levens@...n.ch>
>> >  ---
>> >    Documentation/hwmon/ltc2990 |  24 ++++--
>> >    drivers/hwmon/Kconfig       |   7 +-
>> >    drivers/hwmon/ltc2990.c     | 196 
>> >    +++++++++++++++++++++++++++++++++++++-------
>> >    3 files changed, 185 insertions(+), 42 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@...ic.nl>
>> >  +        Tom Levens <tom.levens@...n.ch>
>> >    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 5ef2814..578e5a9 100644
>> >  --- a/drivers/hwmon/Kconfig
>> >  +++ b/drivers/hwmon/Kconfig
>> >  @@ -709,15 +709,12 @@ 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 e320d21..32f3a8d 100644
>> >  --- a/drivers/hwmon/ltc2990.c
>> >  +++ b/drivers/hwmon/ltc2990.c
>> >  @@ -5,10 +5,6 @@
>> >     * Author: Mike Looijmans <mike.looijmans@...ic.nl>
>> >     *
>> >     * 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.
>> >    */
>> >    #include <linux/bitops.h>
>> >  @@ -18,6 +14,7 @@
>> >    #include <linux/i2c.h>
>> >    #include <linux/kernel.h>
>> >    #include <linux/module.h>
>> >  +#include <linux/of.h>
>> >    #define LTC2990_STATUS    0x00
>> >    #define LTC2990_CONTROL    0x01
>> >  @@ -29,35 +26,109 @@
>> >    #define LTC2990_V4_MSB    0x0C
>> >    #define LTC2990_VCC_MSB    0x0E
>> >  -#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_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)
>> >  +#define LTC2990_NONE    0
>> >  +#define LTC2990_ALL    GENMASK(9, 0)
>> >  +
>> >  +#define LTC2990_MODE0_SHIFT    0
>> >  +#define LTC2990_MODE0_MASK    GENMASK(2, 0)
>> >  +#define LTC2990_MODE1_SHIFT    3
>> >  +#define LTC2990_MODE1_MASK    GENMASK(1, 0)
>> >  +
>> >  +/* Enabled measurements for mode bits 2..0 */
>> >  +static const int ltc2990_attrs_ena_0[] = {
>> >  +    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
>> >  +};
>> >  +
>> >  +/* Enabled measurements for mode bits 4..3 */
>> >  +static const int ltc2990_attrs_ena_1[] = {
>> >  +    LTC2990_NONE,
>> >  +    LTC2990_TEMP2 | LTC2990_IN1 | LTC2990_CURR1,
>> >  +    LTC2990_TEMP3 | LTC2990_IN3 | LTC2990_CURR2,
>> >  +    LTC2990_ALL
>> >  +};
>> >  +
>> >  +struct ltc2990_data {
>> >  +    struct i2c_client *i2c;
>> >  +    u32 mode[2];
>> >  +};
>> >    /* Return the converted value from the given register in uV or mC */
>> >  -static int ltc2990_get_value(struct i2c_client *i2c, u8 reg, int 
>> >  *result)
>> >  +static int ltc2990_get_value(struct i2c_client *i2c, int index, int 
>> >  *result)
>> >    {
>> >        int 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 */
>> >            *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 */
>> >        }
>> >  @@ -69,48 +140,117 @@ 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);
>> >        int 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);
>> >  +
>> >  +    int attrs_mask = LTC2990_IN0 | LTC2990_TEMP1 |
>> >  +             ltc2990_attrs_ena_0[data->mode[0]] &
>> >  +             ltc2990_attrs_ena_1[data->mode[1]];
>> >  +
>> >  +    if (attr->index & attrs_mask)
>> >  +        return a->mode;
>> >  +
>> >  +    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) {
>> >  +        ret = of_property_read_u32_array(of_node, "lltc,meas-mode",
>> >  +                         data->mode, 2);
>> >  +        if (ret < 0)
>> >  +            return ret;
>> >  +
>> >  +        if (data->mode[0] & ~LTC2990_MODE0_MASK ||
>> >  +            data->mode[1] & ~LTC2990_MODE1_MASK)
>> >  +            return -EINVAL;
>> >  +    } else {
>> >  +        ret = i2c_smbus_read_byte_data(i2c, LTC2990_CONTROL);
>> >  +        if (ret < 0)
>> >  +            return ret;
>> >  +
>> >  +        data->mode[0] = ret >> LTC2990_MODE0_SHIFT & 
>> >  LTC2990_MODE0_MASK;
>> >  +        data->mode[1] = ret >> LTC2990_MODE1_SHIFT & 
>> >  LTC2990_MODE1_MASK;
>> >  +    }
>> >  +
>> >  +    /* Setup continuous mode */
>> >        ret = i2c_smbus_write_byte_data(i2c, LTC2990_CONTROL,
>> >  -                    LTC2990_CONTROL_MEASURE_ALL |
>> >  -                    LTC2990_CONTROL_MODE_CURRENT);
>> >  +                    data->mode[0] << LTC2990_MODE0_SHIFT |
>> >  +                    data->mode[1] << LTC2990_MODE1_SHIFT);
>> >        if (ret < 0) {
>> >            dev_err(&i2c->dev, "Error: Failed to set control mode.\n");
>> >            return ret;
>> >  @@ -124,7 +264,7 @@ 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@...icproducts.com
>>  Website: www.topicproducts.com
>>
>>  Please consider the environment before printing this e-mail
>>
>>
>>
>> 
>
>

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