Re: [PATCH v2 1/3] pmbus: introduce PMBUS_VIRT_*_SAMPLES registers

["Adamski, Krzysztof (Nokia - PL/Wroclaw)" <krzysztof.adamski@nokia.com>]

On Sun, Apr 14, 2019 at 07:27:47AM -0700, Guenter Roeck wrote:
>On 4/13/19 9:03 AM, Adamski, Krzysztof (Nokia - PL/Wroclaw) wrote:
>>Those virtual registers can be used to export manufacturer specific
>>functionality for controlling the number of samples for average values
>>reported by the device.
>>
>>Signed-off-by: Krzysztof Adamski <krzysztof.adamski@nokia.com>
>>---
>>  Documentation/hwmon/sysfs-interface |  18 +++++
>>  drivers/hwmon/pmbus/pmbus.h         |  15 ++++
>>  drivers/hwmon/pmbus/pmbus_core.c    | 114 ++++++++++++++++++++++++++++
>>  3 files changed, 147 insertions(+)
>>
>>diff --git a/Documentation/hwmon/sysfs-interface b/Documentation/hwmon/sysfs-interface
>>index 2b9e1005d88b..7b91706d01c8 100644
>>--- a/Documentation/hwmon/sysfs-interface
>>+++ b/Documentation/hwmon/sysfs-interface
>>@@ -756,6 +756,24 @@ intrusion[0-*]_beep
>>  		1: enable
>>  		RW
>>+********************************
>>+* Average sample configuration *
>>+********************************
>>+
>>+Devices allowing for reading {in,power,curr,temp}_average values may export
>>+attributes for controlling number of samples used to compute average.
>>+
>>+samples		Sets number of average samples for all types of measurements.
>>+		RW
>>+
>>+in_samples
>>+power_samples
>>+curr_samples
>>+temp_samples    Sets number of average samples for specific type of measurements.
>>+		Note that on some devices it won't be possible to set all of them
>>+		to different values so changing one might also change some others.
>>+		RW
>>+
>
>Separate patch for the above, please. Adding the ABI is one subject, adding support
>for it into a driver (or driver core) is another.

Sure, I'll do that.

>
>>  sysfs attribute writes interpretation
>>  -------------------------------------
>>diff --git a/drivers/hwmon/pmbus/pmbus.h b/drivers/hwmon/pmbus/pmbus.h
>>index 1d24397d36ec..e73289cc867d 100644
>>--- a/drivers/hwmon/pmbus/pmbus.h
>>+++ b/drivers/hwmon/pmbus/pmbus.h
>>@@ -217,6 +217,20 @@ enum pmbus_regs {
>>  	PMBUS_VIRT_PWM_ENABLE_2,
>>  	PMBUS_VIRT_PWM_ENABLE_3,
>>  	PMBUS_VIRT_PWM_ENABLE_4,
>>+
>>+	/* Samples for average
>>+	 *
>>+	 * Drivers wanting to expose functionality for changing the number of
>>+	 * samples used for average values should implement support in
>>+	 * {read,write}_word_data callback for either PMBUS_VIRT_SAMPLES if it
>>+	 * applies to all types of measurements, or any number of specific
>>+	 * PMBUS_VIRT_*_SAMPLES registers to allow for individual control.
>>+	 */
>>+	PMBUS_VIRT_SAMPLES,
>>+	PMBUS_VIRT_IN_SAMPLES,
>>+	PMBUS_VIRT_CURR_SAMPLES,
>>+	PMBUS_VIRT_POWER_SAMPLES,
>>+	PMBUS_VIRT_TEMP_SAMPLES,
>>  };
>>  /*
>>@@ -371,6 +385,7 @@ enum pmbus_sensor_classes {
>>  #define PMBUS_HAVE_STATUS_VMON	BIT(19)
>>  #define PMBUS_HAVE_PWM12	BIT(20)
>>  #define PMBUS_HAVE_PWM34	BIT(21)
>>+#define PMBUS_HAVE_SAMPLES	BIT(22)
>>  #define PMBUS_PAGE_VIRTUAL	BIT(31)
>>diff --git a/drivers/hwmon/pmbus/pmbus_core.c b/drivers/hwmon/pmbus/pmbus_core.c
>>index 2e2b5851139c..31b6bf49518c 100644
>>--- a/drivers/hwmon/pmbus/pmbus_core.c
>>+++ b/drivers/hwmon/pmbus/pmbus_core.c
>>@@ -1901,6 +1901,116 @@ static int pmbus_add_fan_attributes(struct i2c_client *client,
>>  	return 0;
>>  }
>>+struct pmbus_samples_attr {
>>+	int reg;
>>+	char *name;
>>+};
>>+
>>+struct pmbus_samples_reg {
>>+	int page;
>>+	struct pmbus_samples_attr *attr;
>>+	struct device_attribute dev_attr;
>>+};
>>+
>>+static struct pmbus_samples_attr pmbus_samples_registers[] = {
>>+	{
>>+		.reg = PMBUS_VIRT_SAMPLES,
>>+		.name = "samples",
>>+	}, {
>>+		.reg = PMBUS_VIRT_IN_SAMPLES,
>>+		.name = "in_samples",
>>+	}, {
>>+		.reg = PMBUS_VIRT_CURR_SAMPLES,
>>+		.name = "curr_samples",
>>+	}, {
>>+		.reg = PMBUS_VIRT_POWER_SAMPLES,
>>+		.name = "power_samples",
>>+	}, {
>>+		.reg = PMBUS_VIRT_TEMP_SAMPLES,
>>+		.name = "temp_samples",
>>+	}
>>+};
>>+
>>+#define to_samples_reg(x) container_of(x, struct pmbus_samples_reg, dev_attr)
>>+
>>+static ssize_t pmbus_show_samples(struct device *dev,
>>+				  struct device_attribute *devattr, char *buf)
>>+{
>>+	int val;
>>+	struct i2c_client *client = to_i2c_client(dev->parent);
>>+	struct pmbus_samples_reg *reg = to_samples_reg(devattr);
>>+
>>+	val = _pmbus_read_word_data(client, reg->page, reg->attr->reg);
>>+	if (val < 0)
>>+		return val;
>>+
>>+	return snprintf(buf, PAGE_SIZE, "%d\n", val);
>>+}
>>+
>>+static ssize_t pmbus_set_samples(struct device *dev,
>>+				 struct device_attribute *devattr,
>>+				 const char *buf, size_t count)
>>+{
>>+	int ret;
>>+	long val;
>>+	struct i2c_client *client = to_i2c_client(dev->parent);
>>+	struct pmbus_samples_reg *reg = to_samples_reg(devattr);
>>+
>>+	if (kstrtol(buf, 0, &val) < 0)
>>+		return -EINVAL;
>>+
>>+	ret = _pmbus_write_word_data(client, reg->page, reg->attr->reg, val);
>>+
>>+	return ret ? : count;
>>+}
>>+
>>+static int pmbus_add_samples_attr(struct pmbus_data *data, int page,
>>+				  struct pmbus_samples_attr *attr)
>>+{
>>+	struct pmbus_samples_reg *reg;
>>+
>>+	reg = devm_kzalloc(data->dev, sizeof(*reg), GFP_KERNEL);
>>+	if (!reg)
>>+		return -ENOMEM;
>>+
>>+	reg->attr = attr;
>>+	reg->page = page;
>>+
>>+	pmbus_dev_attr_init(&reg->dev_attr, attr->name, (S_IWUSR | S_IRUGO),
>
>S_IWUSR ran out of favor and generates a checkpatch warning.
>Please use 0644.

I wasn't sure if its more important to care about checkpatch warning or
to keep convention in the file. I'll change to numerical value as
advised.
>
>>+			    pmbus_show_samples, pmbus_set_samples);
>>+
>>+	return pmbus_add_attribute(data, &reg->dev_attr.attr);
>>+}
>>+
>>+static int pmbus_add_samples_attributes(struct i2c_client *client,
>>+					struct pmbus_data *data)
>>+{
>>+	const struct pmbus_driver_info *info = data->info;
>>+	int page;
>>+
>>+	for (page = 0; page < info->pages; page++) {
>
>This won't work as intended on multi-page chips. If the driver writer
>is not careful, it will try to generate multiple similar attributes,
>one per page. I would suggest to only check this for page 0.
>At some point we may need to add a separate func pointer for
>chip specific attributes, but that should do for now.
>
Good point. I'll do that.

>>+		int s;:
>>+
>>+		if (!(info->func[page] & PMBUS_HAVE_SAMPLES))
>>+			continue;
>>+
>>+		for (s = 0; s < ARRAY_SIZE(pmbus_samples_registers); s++) {
>>+			int ret;
>>+			struct pmbus_samples_attr *attr;
>>+
>
>Please use reverse christmas tree here
>
>			struct pmbus_samples_attr *attr;
>			int ret;

Ok.

>>+			attr = &pmbus_samples_registers[s];
>>+			if (!pmbus_check_word_register(client, page, attr->reg))
>>+				continue;
>>+
>>+			ret = pmbus_add_samples_attr(data, page, attr);
>>+			if (ret)
>>+				return ret;
>>+		}
>>+	}
>>+
>>+	return 0;
>>+}
>>+
>>  static int pmbus_find_attributes(struct i2c_client *client,
>>  				 struct pmbus_data *data)
>>  {
>>@@ -1932,6 +2042,10 @@ static int pmbus_find_attributes(struct i2c_client *client,
>>  	/* Fans */
>>  	ret = pmbus_add_fan_attributes(client, data);
>>+	if (ret)
>>+		return ret;
>>+
>>+	ret = pmbus_add_samples_attributes(client, data);
>>  	return ret;
>>  }
>>
>

Krzysztof