On 08/06/2013 11:52 PM, Wei Ni wrote:
The device lm90 can be controlled by the vdd rail.
Adding the power control support to power on/off the vdd rail.
And make sure that power is enabled before accessing the device.
Signed-off-by: Wei Ni <wni@xxxxxxxxxx>
---
drivers/hwmon/lm90.c | 52 ++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 52 insertions(+)
diff --git a/drivers/hwmon/lm90.c b/drivers/hwmon/lm90.c
index cdff742..eeb0115 100644
--- a/drivers/hwmon/lm90.c
+++ b/drivers/hwmon/lm90.c
@@ -89,6 +89,8 @@
#include <linux/err.h>
#include <linux/mutex.h>
#include <linux/sysfs.h>
+#include <linux/delay.h>
+#include <linux/regulator/consumer.h>
/*
* Addresses to scan
@@ -179,6 +181,8 @@ enum chips { lm90, adm1032, lm99, lm86, max6657, max6659, adt7461, max6680,
#define LM90_HAVE_TEMP3 (1 << 6) /* 3rd temperature sensor */
#define LM90_HAVE_BROKEN_ALERT (1 << 7) /* Broken alert */
+#define POWER_ON_DELAY 20 /*ms*/
+
/*
* Driver data (common to all clients)
*/
@@ -302,6 +306,7 @@ static const struct lm90_params lm90_params[] = {
struct lm90_data {
struct device *hwmon_dev;
struct mutex update_lock;
+ struct regulator *lm90_reg;
char valid; /* zero until following fields are valid */
unsigned long last_updated; /* in jiffies */
int kind;
@@ -1391,6 +1396,48 @@ static void lm90_init_client(struct i2c_client *client)
i2c_smbus_write_byte_data(client, LM90_REG_W_CONFIG1, config);
}
+static int lm90_power_control(struct i2c_client *client, bool is_enable)
+{
+ struct lm90_data *data = i2c_get_clientdata(client);
+ int ret;
+
+ mutex_lock(&data->update_lock);
+
+ if (!data->lm90_reg) {
+ data->lm90_reg = regulator_get(&client->dev, "vdd");
+ if (IS_ERR_OR_NULL(data->lm90_reg)) {
+ if (PTR_ERR(data->lm90_reg) == -ENODEV)
+ dev_info(&client->dev,
+ "No regulator found for vdd. Assuming vdd is always powered.");
+ else
+ dev_warn(&client->dev,
+ "Error [%ld] in getting the regulator handle for vdd.\n",
+ PTR_ERR(data->lm90_reg));
+ data->lm90_reg = NULL;
+ mutex_unlock(&data->update_lock);
+ return -ENODEV;
I don't think it is acceptable to have the driver fail on pretty much all PCs.
Also, I dislike that - even if the calling code doesn't fail - the above message would be displayed on unload as well.
In general, the 'unload' flag seems unnecessary. You could just call
if (data->lm90_reg)
regulator_disable();
in the remove function. In addition to that, shouldn't you call regulator_put() on exit ?
Also, I am missing error handling in the probe function; if something else fails,
the regulator is neither disabled nor released.
Guenter
+ }
+ }
+ if (is_enable) {
+ ret = regulator_enable(data->lm90_reg);
+ msleep(POWER_ON_DELAY);
+ } else {
+ ret = regulator_disable(data->lm90_reg);
+ }
+
+ if (ret < 0)
+ dev_err(&client->dev,
+ "Error in %s rail vdd, error %d\n",
+ (is_enable) ? "enabling" : "disabling", ret);
+ else
+ dev_info(&client->dev, "success in %s rail vdd\n",
+ (is_enable) ? "enabling" : "disabling");
+
+ mutex_unlock(&data->update_lock);
+
+ return ret;
+}
+
static int lm90_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
@@ -1406,6 +1453,10 @@ static int lm90_probe(struct i2c_client *client,
i2c_set_clientdata(client, data);
mutex_init(&data->update_lock);
+ err = lm90_power_control(client, true);
+ if (err < 0)
+ return err;
+
/* Set the device type */
data->kind = id->driver_data;
if (data->kind == adm1032) {
@@ -1483,6 +1534,7 @@ static int lm90_remove(struct i2c_client *client)
hwmon_device_unregister(data->hwmon_dev);
lm90_remove_files(client, data);
lm90_restore_conf(client, data);
+ lm90_power_control(client, false);
return 0;
}
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