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Subject[PATCH 2/4] power: bq20z75: add i2c retry mechanism
Date
From: Rhyland Klein <rklein@nvidia.com>

With the support of platform data, now adding support for option i2c retries
on read/write failures. Ths is specified through the optional platform data.

Signed-off-by: Rhyland Klein <rklein@nvidia.com>
---
drivers/power/bq20z75.c | 37 +++++++++++++++++++++++++++++++------
include/linux/power/bq20z75.h | 2 ++
2 files changed, 33 insertions(+), 6 deletions(-)
diff --git a/drivers/power/bq20z75.c b/drivers/power/bq20z75.c
index a51e98d..e82d10e 100644
--- a/drivers/power/bq20z75.c
+++ b/drivers/power/bq20z75.c
@@ -156,30 +156,55 @@ struct bq20z75_info {

static int bq20z75_read_word_data(struct i2c_client *client, u8 address)
{
- s32 ret;
+ struct bq20z75_info *bq20z75_device = i2c_get_clientdata(client);
+ s32 ret = 0;
+ int retries = 1;
+
+ if (bq20z75_device->pdata)
+ retries = max(bq20z75_device->pdata->i2c_retry_count + 1, 1);
+
+ while (retries > 0) {
+ ret = i2c_smbus_read_word_data(client, address);
+ if (ret >= 0)
+ break;
+ retries--;
+ }

- ret = i2c_smbus_read_word_data(client, address);
if (ret < 0) {
- dev_err(&client->dev,
+ dev_warn(&client->dev,
"%s: i2c read at address 0x%x failed\n",
__func__, address);
return ret;
}
+
return le16_to_cpu(ret);
}

static int bq20z75_write_word_data(struct i2c_client *client, u8 address,
u16 value)
{
- s32 ret;
+ struct bq20z75_info *bq20z75_device = i2c_get_clientdata(client);
+ s32 ret = 0;
+ int retries = 1;
+
+ if (bq20z75_device->pdata)
+ retries = max(bq20z75_device->pdata->i2c_retry_count + 1, 1);
+
+ while (retries > 0) {
+ ret = i2c_smbus_write_word_data(client, address,
+ le16_to_cpu(value));
+ if (ret >= 0)
+ break;
+ retries--;
+ }

- ret = i2c_smbus_write_word_data(client, address, le16_to_cpu(value));
if (ret < 0) {
- dev_err(&client->dev,
+ dev_warn(&client->dev,
"%s: i2c write to address 0x%x failed\n",
__func__, address);
return ret;
}
+
return 0;
}

diff --git a/include/linux/power/bq20z75.h b/include/linux/power/bq20z75.h
index 0e1b8a2..b0843b6 100644
--- a/include/linux/power/bq20z75.h
+++ b/include/linux/power/bq20z75.h
@@ -28,10 +28,12 @@
* struct bq20z75_platform_data - platform data for bq20z75 devices
* @battery_detect: GPIO which is used to detect battery presence
* @battery_detect_present: gpio state when battery is present (0 / 1)
+ * @i2c_retry_count: # of times to retry on i2c IO failure
*/
struct bq20z75_platform_data {
int battery_detect;
int battery_detect_present;
+ int i2c_retry_count;
};

#endif
--
1.7.0.4


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