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SubjectRe: [PATCH] hwmon: ltc2990: support all measurement modes
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Date
On 11/16/2016 05:53 AM, Tom Levens wrote:
> Updated ltc2990 driver to support all possible measurement modes that
> the chip provides. Mode can be set through a device tree attribute or by
> writing to the "mode" sysfs attribute.
>
> Signed-off-by: Tom Levens <tom.levens@cern.ch>
> ---
> .../devicetree/bindings/hwmon/ltc2990.txt | 15 +
> Documentation/hwmon/ltc2990 | 25 ++-
> drivers/hwmon/Kconfig | 7 +-
> drivers/hwmon/ltc2990.c | 268 +++++++++++++++++---
> 4 files changed, 266 insertions(+), 49 deletions(-)
> create mode 100644 Documentation/devicetree/bindings/hwmon/ltc2990.txt
>
> diff --git a/Documentation/devicetree/bindings/hwmon/ltc2990.txt b/Documentation/devicetree/bindings/hwmon/ltc2990.txt
> new file mode 100644
> index 0000000..0a17e8d
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/hwmon/ltc2990.txt
> @@ -0,0 +1,15 @@
> +ltc2990
> +
> +Required properties:
> +- compatible: must be "lltc,ltc2990"
> +- reg: I2C slave address
> +
> +Optional properties:
> +- mode: measurement mode (0-7), see Documentation/hwmon/ltc2990 for details
> +
This needs to be documented here.

> +Example:
> +ltc2990@4c {
> + compatible = "lltc,ltc2990";
> + mode = <7>;
> + reg = <0x4c>;
> +};

Please submit as separate patch and copy devicetree maintainers for Ack.
You'll probably want to specify valid modes and their impact.

> diff --git a/Documentation/hwmon/ltc2990 b/Documentation/hwmon/ltc2990
> index c25211e..a97df88 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@topic.nl>
> + Tom Levens <tom.levens@cern.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 +31,20 @@ 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
> +mode Set the measurement mode (range 0 to 7)
> +
The mode is determined by the hardware configuration. It does not make sense
to have it user configurable.

> +A subset of the following attributes are visible, depending on the programmed
> +measurement mode.
> +
> +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 8f8fe05..b6f910d 100644
> --- a/drivers/hwmon/ltc2990.c
> +++ b/drivers/hwmon/ltc2990.c
> @@ -4,11 +4,10 @@
> * Copyright (C) 2014 Topic Embedded Products
> * Author: Mike Looijmans <mike.looijmans@topic.nl>
> *
> - * License: GPLv2
> + * Copyright (C) 2016 European Organization for Nuclear Research (CERN)
> + * Author: Tom Levens <tom.levens@cern.ch>
> *
Please specify your changes. Something like "Support for all chip modes by ..."
would be more appropriate.

> - * 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.
> + * License: GPLv2
> */
>
> #include <linux/err.h>
> @@ -17,6 +16,7 @@
> #include <linux/i2c.h>
> #include <linux/kernel.h>
> #include <linux/module.h>
> +#include <linux/of.h>
>
> #define LTC2990_STATUS 0x00
> #define LTC2990_CONTROL 0x01
> @@ -31,8 +31,36 @@
> #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
> +#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;
> + struct mutex update_lock;
> + u32 mode;
> +};
>
> /* convert raw register value to sign-extended integer in 16-bit range */
> static int ltc2990_voltage_to_int(int raw)
> @@ -44,30 +72,68 @@ static int ltc2990_voltage_to_int(int raw)
> }
>
> /* 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, 13-bit */
> val = (val & 0x1FFF) << 3;
> *result = (val * 1000) >> 7;

Turns out this is actually wrong. Bit 12 is a sign bit per datasheet.
Separate problem, though, and should be fixed with a separate patch.
The first line should probably use sign_extend().

> 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 = ltc2990_voltage_to_int(val) * 1942 / (4 * 100);

Hmmm .. voltage_to_int() always adds two bits which are then just taken off
subsequently. Another unrelated change - ltc2990_voltage_to_int() should
just use sign_extend() and not bother shifting the result to the left.
Or maybe just use sign_extend() and drop ltc2990_voltage_to_int() entirely.

Another separate patch, though.

> break;
> - case LTC2990_VCC_MSB:
> - /* Vcc, 305.18μV/LSB, 2.5V offset */
> + case LTC2990_IN0:
> + /* Vcc, 305.18uV/LSB, 2.5V offset */
> *result = (ltc2990_voltage_to_int(val) * 30518 /
> (4 * 100 * 1000)) + 2500;
> break;
> + case LTC2990_IN1:
> + case LTC2990_IN2:
> + case LTC2990_IN3:
> + case LTC2990_IN4:
> + /* Vx: 305.18uV/LSB */
> + *result = (ltc2990_voltage_to_int(val) * 30518 /
> + (4 * 100 * 1000));
> + break;
> default:
> return -EINVAL; /* won't happen, keep compiler happy */
> }
> @@ -75,66 +141,198 @@ static int ltc2990_get_value(struct i2c_client *i2c, u8 reg, int *result)
> return 0;
> }
>
> +
No double empty lines please.

> +static int ltc2990_write_control_trigger(struct ltc2990_data *data)
> +{

more like ltc2990_init_chip().

> + int ret;
> +
> + /* Setup continuous mode */
> + ret = i2c_smbus_write_byte_data(data->i2c, LTC2990_CONTROL,
> + LTC2990_CONTROL_MEASURE_ALL |
> + data->mode);
> + if (unlikely(ret < 0)) {
> + dev_err(&data->i2c->dev,
> + "Error: Failed to set control mode.\n");
> + return ret;
> + }
> + /* Trigger once to start continuous conversion */
> + ret = i2c_smbus_write_byte_data(data->i2c, LTC2990_TRIGGER, 0x01);
> + if (unlikely(ret < 0)) {
> + dev_err(&data->i2c->dev,
> + "Error: Failed to start acquisition.\n");

This looks like a bad multi-line alignment. Please align continuation lines with '('.

> + return ret;
> + }
> +
> + return 0;
> +}
> +
> 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 ssize_t ltc2990_get_mode(struct device *dev,
> + struct device_attribute *da, char *buf)
> +{
> + struct ltc2990_data *data = dev_get_drvdata(dev);
> +
> + return snprintf(buf, PAGE_SIZE, "%d\n", data->mode);
> +}
> +
> +static const struct attribute_group ltc2990_group;
> +
> +static ssize_t ltc2990_set_mode(struct device *dev,
> + struct device_attribute *da,
> + const char *buf, size_t count)
> +{
> + struct ltc2990_data *data = dev_get_drvdata(dev);
> + int ret;
> + unsigned long mode;
> +
> + ret = kstrtoul(buf, 10, &mode);
> + if (unlikely(ret))
> + return ret;
> +
> + if (mode > LTC2990_CONTROL_MODE_MAX)
> + return -EINVAL;
> +
> + mutex_lock(&data->update_lock);
> +
> + data->mode = mode;
> +
> + ret = ltc2990_write_control_trigger(data);
> + if (unlikely(ret < 0))
> + goto abort;
> +
> + ret = sysfs_update_group(&dev->kobj, &ltc2990_group);
> + if (unlikely(ret < 0))
> + goto abort;
> +
> + ret = count;
> +
> +abort:
> + mutex_unlock(&data->update_lock);
> + return ret;
> +}

As mentioned above, mode is a hardware configuration and should not be
changeable (or accessible, for that matter) using a sysfs attribute.

> +
> +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 (ltc2990_attrs_ena[data->mode] & attr->index)
> + return a->mode;
> + 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 SENSOR_DEVICE_ATTR(mode, S_IRUGO | S_IWUSR, ltc2990_get_mode,
> + ltc2990_set_mode, 0);
>
> 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_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,
> +};
> +
> +static const struct attribute_group ltc2990_group = {
> + .attrs = ltc2990_attrs,
> + .is_visible = ltc2990_attrs_visible,
> +};
> +
> +static struct attribute *ltc2990_static_attrs[] = {
> + &sensor_dev_attr_temp1_input.dev_attr.attr,
> &sensor_dev_attr_in0_input.dev_attr.attr,
> + &sensor_dev_attr_mode.dev_attr.attr,
> + NULL,
> +};
> +
> +static const struct attribute_group ltc2990_static_group = {
> + .attrs = ltc2990_static_attrs
> +};
> +
> +static const struct attribute_group *ltc2990_groups[] = {
> + &ltc2990_group,
> + &ltc2990_static_group,
> NULL,
> };
> -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 */
> - ret = i2c_smbus_write_byte_data(i2c, LTC2990_CONTROL,
> - LTC2990_CONTROL_MEASURE_ALL |
> - LTC2990_CONTROL_MODE_CURRENT);
> - if (ret < 0) {
> - dev_err(&i2c->dev, "Error: Failed to set control mode.\n");
> - return ret;
> + 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, "mode", &data->mode))
> + data->mode = LTC2990_CONTROL_MODE_DEFAULT;
> +
> + if (data->mode > LTC2990_CONTROL_MODE_MAX) {
> + dev_warn(&data->i2c->dev,
> + "Warning: Mode %d out of range, defaulting to %d.\n",
> + data->mode, LTC2990_CONTROL_MODE_DEFAULT);
> + data->mode = LTC2990_CONTROL_MODE_DEFAULT;

This should fail loading the driver with -EINVAL.

> }
> - /* Trigger once to start continuous conversion */
> - ret = i2c_smbus_write_byte_data(i2c, LTC2990_TRIGGER, 1);
> - if (ret < 0) {
> - dev_err(&i2c->dev, "Error: Failed to start acquisition.\n");
> +
> + ret = ltc2990_write_control_trigger(data);
> + if (unlikely(ret < 0))
> return ret;
> - }
> +
> + mutex_init(&data->update_lock);
>
> hwmon_dev = devm_hwmon_device_register_with_groups(&i2c->dev,
> i2c->name,
> - i2c,
> + data,
> ltc2990_groups);
>
> return PTR_ERR_OR_ZERO(hwmon_dev);
>

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