On 12/10/2014 02:38 AM, Bartosz Golaszewski wrote:
The shunt resistance can only be set via platform_data or device tree. This
isn't suitable for devices in which the shunt resistance can change/isn't
known at boot-time.
Add a sysfs attribute that allows to read and set the shunt resistance.
Signed-off-by: Bartosz Golaszewski <bgolaszewski@xxxxxxxxxxxx>
---
drivers/hwmon/ina2xx.c | 74 ++++++++++++++++++++++++++++++++++++++++++++------
1 file changed, 65 insertions(+), 9 deletions(-)
diff --git a/drivers/hwmon/ina2xx.c b/drivers/hwmon/ina2xx.c
index e01feba..6e73add 100644
--- a/drivers/hwmon/ina2xx.c
+++ b/drivers/hwmon/ina2xx.c
@@ -51,7 +51,6 @@
#define INA226_ALERT_LIMIT 0x07
#define INA226_DIE_ID 0xFF
-
While nice, this is an unrelated change.
/* register count */
#define INA219_REGISTERS 6
#define INA226_REGISTERS 8
@@ -65,6 +64,9 @@
/* worst case is 68.10 ms (~14.6Hz, ina219) */
#define INA2XX_CONVERSION_RATE 15
+/* default shunt resistance */
+#define INA2XX_RSHUNT_DEFAULT 10000
+
enum ina2xx_ids { ina219, ina226 };
struct ina2xx_config {
@@ -87,6 +89,8 @@ struct ina2xx_data {
int kind;
u16 regs[INA2XX_MAX_REGISTERS];
+
+ long rshunt;
};
static const struct ina2xx_config ina2xx_config[] = {
@@ -110,6 +114,11 @@ static const struct ina2xx_config ina2xx_config[] = {
},
};
+static u16 ina2xx_calibration_val(const struct ina2xx_data *data)
+{
+ return data->config->calibration_factor / data->rshunt;
+}
+
static struct ina2xx_data *ina2xx_update_device(struct device *dev)
{
struct ina2xx_data *data = dev_get_drvdata(dev);
@@ -164,6 +173,13 @@ static int ina2xx_get_value(struct ina2xx_data *data, u8 reg)
/* signed register, LSB=1mA (selected), in mA */
val = (s16)data->regs[reg];
break;
+ case INA2XX_CALIBRATION:
+ if (data->regs[reg] == 0)
+ val = 0;
+ else
+ val = data->config->calibration_factor
+ / data->regs[reg];
+ break;
This doesn't really make sense. What you want to show is rshunt, not the above.
I think it would be better to write a separate show function to display it.
default:
/* programmer goofed */
WARN_ON_ONCE(1);
@@ -187,6 +203,38 @@ static ssize_t ina2xx_show_value(struct device *dev,
ina2xx_get_value(data, attr->index));
}
+static ssize_t ina2xx_set_shunt(struct device *dev,
+ struct device_attribute *da,
+ const char *buf, size_t count)
+{
+ struct ina2xx_data *data = ina2xx_update_device(dev);
+ unsigned long val;
+ int status;
+
+ if (IS_ERR(data))
+ return PTR_ERR(data);
+
+ status = kstrtoul(buf, 10, &val);
+ if (status < 0)
+ return status;
+
+ if (val == 0 ||
+ /* Values greater than the calibration factor make no sense. */
+ val > data->config->calibration_factor ||
+ val > LONG_MAX)
data->config->calibration_factor is <= LONG_MAX, so the second check is unnecessary.
Actually, given that calibration_factor is chip dependent and not necessarily known
by the user, it would make more sense to only bail out on == 0 and then use clamp_val
to limit the range to (1, data->config->calibration_factor).
Guenter
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