Messages in this thread Patch in this message | | | Date | Wed, 07 Aug 2013 00:03:20 -0700 | From | Guenter Roeck <> | Subject | Re: [PATCH 1/2] hwmon: (lm90) Add power control |
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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@nvidia.com> > --- > 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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