Adding Tomasz...
> -----Original Message-----
> From: Mohandass, Divagar
> Sent: Monday, September 04, 2017 3:29 AM
> To: robh+dt@xxxxxxxxxx; mark.rutland@xxxxxxx; wsa@xxxxxxxxxxxxx;
> sakari.ailus@xxxxxx
> Cc: devicetree@xxxxxxxxxxxxxxx; linux-i2c@xxxxxxxxxxxxxxx; linux-
> kernel@xxxxxxxxxxxxxxx; Mani, Rajmohan <rajmohan.mani@xxxxxxxxx>;
> Mohandass, Divagar <divagar.mohandass@xxxxxxxxx>
> Subject: [PATCH v6 3/3] eeprom: at24: enable runtime pm support
>
> Currently the device is kept in D0, there is an opportunity to save power by
> enabling runtime pm.
>
> Device can be daisy chained from PMIC and we can't rely on I2C core for auto
> resume/suspend. Driver will decide when to resume/suspend.
>
> Signed-off-by: Divagar Mohandass <divagar.mohandass@xxxxxxxxx>
> ---
> drivers/misc/eeprom/at24.c | 38
> ++++++++++++++++++++++++++++++++++++++
> 1 file changed, 38 insertions(+)
>
> diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c index
> 2199c42..d718a7a 100644
> --- a/drivers/misc/eeprom/at24.c
> +++ b/drivers/misc/eeprom/at24.c
> @@ -24,6 +24,7 @@
> #include <linux/i2c.h>
> #include <linux/nvmem-provider.h>
> #include <linux/platform_data/at24.h>
> +#include <linux/pm_runtime.h>
>
> /*
> * I2C EEPROMs from most vendors are inexpensive and mostly
> interchangeable.
> @@ -501,11 +502,21 @@ static ssize_t at24_eeprom_write_i2c(struct
> at24_data *at24, const char *buf, static int at24_read(void *priv, unsigned int
> off, void *val, size_t count) {
> struct at24_data *at24 = priv;
> + struct i2c_client *client;
> char *buf = val;
> + int ret;
>
> if (unlikely(!count))
> return count;
>
> + client = at24_translate_offset(at24, &off);
> +
> + ret = pm_runtime_get_sync(&client->dev);
> + if (ret < 0) {
> + pm_runtime_put_noidle(&client->dev);
> + return ret;
> + }
> +
> /*
> * Read data from chip, protecting against concurrent updates
> * from this host, but not from other I2C masters.
> @@ -518,6 +529,7 @@ static int at24_read(void *priv, unsigned int off, void
> *val, size_t count)
> status = at24->read_func(at24, buf, off, count);
> if (status < 0) {
> mutex_unlock(&at24->lock);
> + pm_runtime_put(&client->dev);
> return status;
> }
> buf += status;
> @@ -527,17 +539,29 @@ static int at24_read(void *priv, unsigned int off, void
> *val, size_t count)
>
> mutex_unlock(&at24->lock);
>
> + pm_runtime_put(&client->dev);
> +
> return 0;
> }
>
> static int at24_write(void *priv, unsigned int off, void *val, size_t count) {
> struct at24_data *at24 = priv;
> + struct i2c_client *client;
> char *buf = val;
> + int ret;
>
> if (unlikely(!count))
> return -EINVAL;
>
> + client = at24_translate_offset(at24, &off);
> +
> + ret = pm_runtime_get_sync(&client->dev);
> + if (ret < 0) {
> + pm_runtime_put_noidle(&client->dev);
> + return ret;
> + }
> +
> /*
> * Write data to chip, protecting against concurrent updates
> * from this host, but not from other I2C masters.
> @@ -550,6 +574,7 @@ static int at24_write(void *priv, unsigned int off, void
> *val, size_t count)
> status = at24->write_func(at24, buf, off, count);
> if (status < 0) {
> mutex_unlock(&at24->lock);
> + pm_runtime_put(&client->dev);
> return status;
> }
> buf += status;
> @@ -559,6 +584,8 @@ static int at24_write(void *priv, unsigned int off, void
> *val, size_t count)
>
> mutex_unlock(&at24->lock);
>
> + pm_runtime_put(&client->dev);
> +
> return 0;
> }
>
> @@ -743,11 +770,17 @@ static int at24_probe(struct i2c_client *client, const
> struct i2c_device_id *id)
>
> i2c_set_clientdata(client, at24);
>
> + /* enable runtime pm */
> + pm_runtime_get_noresume(&client->dev);
> + pm_runtime_set_active(&client->dev);
> + pm_runtime_enable(&client->dev);
> +
> /*
> * Perform a one-byte test read to verify that the
> * chip is functional.
> */
> err = at24_read(at24, 0, &test_byte, 1);
> + pm_runtime_put(&client->dev);
> if (err) {
> err = -ENODEV;
> goto err_clients;
> @@ -795,6 +828,8 @@ static int at24_probe(struct i2c_client *client, const
> struct i2c_device_id *id)
> if (at24->client[i])
> i2c_unregister_device(at24->client[i]);
>
> + pm_runtime_disable(&client->dev);
> +
> return err;
> }
>
> @@ -810,6 +845,9 @@ static int at24_remove(struct i2c_client *client)
> for (i = 1; i < at24->num_addresses; i++)
> i2c_unregister_device(at24->client[i]);
>
> + pm_runtime_disable(&client->dev);
> + pm_runtime_set_suspended(&client->dev);
> +
> return 0;
> }
>
> --
> 1.9.1
