[PATCH v7 5/5] hwmon: ina2xx: allow to change the averaging rate at run-time

Bartosz Golaszewski
2014-12-13T16:27:59Z

The averaging rate of ina226 is hardcoded to 16 in the driver. Make it
modifiable at run-time via a new sysfs attribute.

While we're at it - add an additional variable to ina2xx_data, which holds
the current configuration settings - this way we'll be able to restore the
configuration in case of an unexpected chip reset.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
---
Documentation/hwmon/ina2xx | 3 ++
drivers/hwmon/ina2xx.c | 132 +++++++++++++++++++++++++++++++++++++++++++--
2 files changed, 131 insertions(+), 4 deletions(-)

diff --git a/Documentation/hwmon/ina2xx b/Documentation/hwmon/ina2xx
index 320dd69..a11256d 100644
--- a/Documentation/hwmon/ina2xx
+++ b/Documentation/hwmon/ina2xx
@@ -48,3 +48,6 @@ The shunt value in micro-ohms can be set via platform data or device tree at
compile-time or via the shunt_resistor attribute in sysfs at run-time. Please
refer to the Documentation/devicetree/bindings/i2c/ina2xx.txt for bindings
if the device tree is used.
+
+The averaging rate of INA226 and INA230 can be changed via the avg_rate sysfs
+attribute. The available rates are: 1, 4, 16, 64, 128, 256, 512 and 1024.
diff --git a/drivers/hwmon/ina2xx.c b/drivers/hwmon/ina2xx.c
index 49537ea..d6fccad 100644
--- a/drivers/hwmon/ina2xx.c
+++ b/drivers/hwmon/ina2xx.c
@@ -68,6 +68,15 @@

#define INA2XX_RSHUNT_DEFAULT 10000

+/* bit masks for the averaging setting in the configuration register */
+#define INA226_AVG_RD_MASK 0x0E00
+#define INA226_AVG_WR_MASK 0xF1FF
+
+#define INA226_READ_AVG(reg) ((reg & INA226_AVG_RD_MASK) >> 9)
+
+/* common attrs, ina226 attrs and NULL */
+#define INA2XX_MAX_ATTRIBUTE_GROUPS 3
+
enum ina2xx_ids { ina219, ina226 };

struct ina2xx_config {
@@ -85,12 +94,14 @@ struct ina2xx_data {
const struct ina2xx_config *config;

long rshunt;
+ u16 curr_config;

struct mutex update_lock;
bool valid;
unsigned long last_updated;

int kind;
+ const struct attribute_group *groups[INA2XX_MAX_ATTRIBUTE_GROUPS];
u16 regs[INA2XX_MAX_REGISTERS];
};

@@ -115,6 +126,38 @@ static const struct ina2xx_config ina2xx_config[] = {
},
};

+/*
+ * Available averaging rates for ina226. The indices correspond with
+ * the bit values expected by the chip (according to the ina226 datasheet,
+ * table 3 AVG bit settings, found at
+ * http://www.ti.com/lit/ds/symlink/ina226.pdf.
+ */
+static const int ina226_avg_tab[] = { 1, 4, 16, 64, 128, 256, 512, 1024 };
+
+static int ina226_avg_bits(int avg)
+{
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(ina226_avg_tab); i++) {
+ if (avg == ina226_avg_tab[i])
+ return i;
+ }
+
+ return -EINVAL;
+}
+
+static int ina226_avg_val(int bits)
+{
+ /*
+ * Value read from the config register should be correct, but do check
+ * the boundary just in case.
+ */
+ if (bits >= ARRAY_SIZE(ina226_avg_tab))
+ return -ENODEV;
+
+ return ina226_avg_tab[bits];
+}
+
static int ina2xx_calibrate(struct ina2xx_data *data)
{
return i2c_smbus_write_word_swapped(data->client, INA2XX_CALIBRATION,
@@ -131,7 +174,7 @@ static int ina2xx_init(struct ina2xx_data *data)

/* device configuration */
ret = i2c_smbus_write_word_swapped(client, INA2XX_CONFIG,
- data->config->config_default);
+ data->curr_config);
if (ret < 0)
return ret;

@@ -292,6 +335,66 @@ static ssize_t ina2xx_set_shunt(struct device *dev,
return count;
}

+static ssize_t ina226_show_avg(struct device *dev,
+ struct device_attribute *da, char *buf)
+{
+ struct ina2xx_data *data = ina2xx_update_device(dev);
+ int avg, i, written = 0;
+ const char *fmt;
+
+ if (IS_ERR(data))
+ return PTR_ERR(data);
+
+ avg = ina226_avg_val(INA226_READ_AVG(data->regs[INA2XX_CONFIG]));
+ if (avg < 0)
+ return avg;
+
+ for (i = 0; i < ARRAY_SIZE(ina226_avg_tab); i++) {
+ if (avg == ina226_avg_tab[i])
+ fmt = "\t[%d]";
+ else
+ fmt = "\t%d";
+
+ written += snprintf(buf + written, PAGE_SIZE - written,
+ fmt, ina226_avg_tab[i]);
+ }
+ written += snprintf(buf + written, PAGE_SIZE - written, "\n");
+
+ return written;
+}
+
+static ssize_t ina226_set_avg(struct device *dev,
+ struct device_attribute *da,
+ const char *buf, size_t count)
+{
+ struct ina2xx_data *data = ina2xx_update_device(dev);
+ long val;
+ int status, avg;
+
+ if (IS_ERR(data))
+ return PTR_ERR(data);
+
+ status = kstrtol(buf, 10, &val);
+ if (status < 0)
+ return status;
+
+ avg = ina226_avg_bits(val);
+ if (avg < 0)
+ return avg;
+
+ mutex_lock(&data->update_lock);
+ data->curr_config = (data->regs[INA2XX_CONFIG] &
+ INA226_AVG_WR_MASK) | (avg << 9);
+ status = i2c_smbus_write_word_swapped(data->client,
+ INA2XX_CONFIG,
+ data->curr_config);
+ mutex_unlock(&data->update_lock);
+ if (status < 0)
+ return status;
+
+ return count;
+}
+
/* shunt voltage */
static SENSOR_DEVICE_ATTR(in0_input, S_IRUGO, ina2xx_show_value, NULL,
INA2XX_SHUNT_VOLTAGE);
@@ -313,6 +416,10 @@ static SENSOR_DEVICE_ATTR(shunt_resistor, S_IRUGO | S_IWUSR,
ina2xx_show_value, ina2xx_set_shunt,
INA2XX_CALIBRATION);

+/* averaging rate */
+static SENSOR_DEVICE_ATTR(avg_rate, S_IRUGO | S_IWUSR,
+ ina226_show_avg, ina226_set_avg, 0);
+
/* pointers to created device attributes */
static struct attribute *ina2xx_attrs[] = {
&sensor_dev_attr_in0_input.dev_attr.attr,
@@ -322,7 +429,19 @@ static struct attribute *ina2xx_attrs[] = {
&sensor_dev_attr_shunt_resistor.dev_attr.attr,
NULL,
};
-ATTRIBUTE_GROUPS(ina2xx);
+
+static const struct attribute_group ina2xx_group = {
+ .attrs = ina2xx_attrs,
+};
+
+static struct attribute *ina226_attrs[] = {
+ &sensor_dev_attr_avg_rate.dev_attr.attr,
+ NULL,
+};
+
+static const struct attribute_group ina226_group = {
+ .attrs = ina226_attrs,
+};

static int ina2xx_probe(struct i2c_client *client,
const struct i2c_device_id *id)
@@ -333,7 +452,7 @@ static int ina2xx_probe(struct i2c_client *client,
struct ina2xx_data *data;
struct device *hwmon_dev;
u32 val;
- int ret;
+ int ret, group = 0;

if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_WORD_DATA))
return -ENODEV;
@@ -355,6 +474,7 @@ static int ina2xx_probe(struct i2c_client *client,
/* set the device type */
data->kind = id->driver_data;
data->config = &ina2xx_config[data->kind];
+ data->curr_config = data->config->config_default;
data->client = client;

if (data->rshunt <= 0 ||
@@ -369,8 +489,12 @@ static int ina2xx_probe(struct i2c_client *client,

mutex_init(&data->update_lock);

+ data->groups[group++] = &ina2xx_group;
+ if (data->kind == ina226)
+ data->groups[group++] = &ina226_group;
+
hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
- data, ina2xx_groups);
+ data, data->groups);
if (IS_ERR(hwmon_dev))
return PTR_ERR(hwmon_dev);

--
2.1.3