[PATCH v3 1/4] pmbus: introduce PMBUS_VIRT_*_SAMPLES registers

[Adamski, Krzysztof (Nokia - PL/Wroclaw)]

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.adam...@nokia.com>
---
 drivers/hwmon/pmbus/pmbus.h      |  15 +++++
 drivers/hwmon/pmbus/pmbus_core.c | 110 +++++++++++++++++++++++++++++++
 2 files changed, 125 insertions(+)

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..9b7d493c98b9 100644
--- a/drivers/hwmon/pmbus/pmbus_core.c
+++ b/drivers/hwmon/pmbus/pmbus_core.c
@@ -1901,6 +1901,112 @@ 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, 0644,
+                           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 s;
+
+       if (!(info->func[0] & PMBUS_HAVE_SAMPLES))
+               return 0;
+
+       for (s = 0; s < ARRAY_SIZE(pmbus_samples_registers); s++) {
+               struct pmbus_samples_attr *attr;
+               int ret;
+
+               attr = &pmbus_samples_registers[s];
+               if (!pmbus_check_word_register(client, 0, attr->reg))
+                       continue;
+
+               ret = pmbus_add_samples_attr(data, 0, attr);
+               if (ret)
+                       return ret;
+       }
+
+       return 0;
+}
+
 static int pmbus_find_attributes(struct i2c_client *client,
                                 struct pmbus_data *data)
 {
@@ -1932,6 +2038,10 @@ 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;
 }
 
-- 
2.20.1