From: linux@roeck-us•net (Guenter Roeck)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH 1/2] hwmon: (lm90) Add power control
Date: Wed, 07 Aug 2013 00:03:20 -0700 [thread overview]
Message-ID: <5201F138.3080906@roeck-us.net> (raw)
In-Reply-To: <1375858358-15070-2-git-send-email-wni@nvidia.com>
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;
> }
>
next prev parent reply other threads:[~2013-08-07 7:03 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-08-07 6:52 [PATCH 0/2] Add power control for lm90 Wei Ni
2013-08-07 6:52 ` [PATCH 1/2] hwmon: (lm90) Add power control Wei Ni
2013-08-07 7:03 ` Guenter Roeck [this message]
2013-08-07 7:15 ` Wei Ni
2013-08-07 7:27 ` Alexander Shiyan
2013-08-07 7:32 ` Wei Ni
2013-08-07 7:50 ` Guenter Roeck
2013-08-07 8:07 ` Wei Ni
2013-08-07 8:45 ` Alexander Shiyan
2013-08-07 9:35 ` Wei Ni
2013-08-07 16:06 ` Stephen Warren
2013-08-07 16:44 ` Guenter Roeck
2013-08-07 7:45 ` Guenter Roeck
2013-08-07 6:52 ` [PATCH 2/2] ARM: dt: t114 dalmore: add dt entry for nct1008 Wei Ni
2013-08-07 16:03 ` Stephen Warren
2013-08-08 2:36 ` Wei Ni
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=5201F138.3080906@roeck-us.net \
--to=linux@roeck-us$(echo .)net \
--cc=linux-arm-kernel@lists$(echo .)infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox