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i2c: Add an interface to lock/unlock an I2C bus segment 

Some drivers need to be able to prevent access to an I2C bus segment
for a specific period of time. Add an interface for them to do so
without twiddling with i2c-core internals.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Acked-by: Ben Hutchings <bhutchings@solarflare.com>
This commit is contained in:
Jean Delvare 2009-11-07 13:10:46 +01:00
parent 3806e94b01
commit afa08974fe
2 changed files with 20 additions and 2 deletions
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4
drivers/net/sfc/sfe4001.c
View File

@ -188,7 +188,7 @@ static int sfn4111t_reset(struct efx_nic *efx)
efx_oword_t reg;
/* GPIO 3 and the GPIO register are shared with I2C, so block that */
mutex_lock(&efx->i2c_adap.bus_lock);
i2c_lock_adapter(&efx->i2c_adap);
/* Pull RST_N (GPIO 2) low then let it up again, setting the
* FLASH_CFG_1 strap (GPIO 3) appropriately. Only change the
@ -204,7 +204,7 @@ static int sfn4111t_reset(struct efx_nic *efx)
falcon_write(efx, &reg, GPIO_CTL_REG_KER);
msleep(1);
mutex_unlock(&efx->i2c_adap.bus_lock);
i2c_unlock_adapter(&efx->i2c_adap);
ssleep(1);
return 0;

18
include/linux/i2c.h
View File

@ -361,6 +361,24 @@ static inline void i2c_set_adapdata(struct i2c_adapter *dev, void *data)
dev_set_drvdata(&dev->dev, data);
}
/**
* i2c_lock_adapter - Prevent access to an I2C bus segment
* @adapter: Target I2C bus segment
*/
static inline void i2c_lock_adapter(struct i2c_adapter *adapter)
{
mutex_lock(&adapter->bus_lock);
}
/**
* i2c_unlock_adapter - Reauthorize access to an I2C bus segment
* @adapter: Target I2C bus segment
*/
static inline void i2c_unlock_adapter(struct i2c_adapter *adapter)
{
mutex_unlock(&adapter->bus_lock);
}
/*flags for the client struct: */
#define I2C_CLIENT_PEC 0x04 /* Use Packet Error Checking */
#define I2C_CLIENT_TEN 0x10 /* we have a ten bit chip address */