From: Hubert Streidl hubert.streidl@de.bosch.com
[ Upstream commit 586478bfc9f7e16504d6f64cf18bcbdf6fd0cbc9 ]
By default the PMIC DA9063 2-wire interface is SMBus compliant. This means the PMIC will automatically reset the interface when the clock signal ceases for more than the SMBus timeout of 35 ms.
If the I2C driver / device is not capable of creating atomic I2C transactions, a context change can cause a ceasing of the clock signal. This can happen if for example a real-time thread is scheduled. Then the DA9063 in SMBus mode will reset the 2-wire interface. Subsequently a write message could end up in the wrong register. This could cause unpredictable system behavior.
The DA9063 PMIC also supports an I2C compliant mode for the 2-wire interface. This mode does not reset the interface when the clock signal ceases. Thus the problem depicted above does not occur.
This patch tests for the bus functionality "I2C_FUNC_I2C". It can reasonably be assumed that the bus cannot obey SMBus timings if this functionality is set. SMBus commands most probably are emulated in this case which is prone to the latency issue described above.
This patch enables the I2C bus mode if I2C_FUNC_I2C is set or otherwise keeps the default SMBus mode.
Signed-off-by: Hubert Streidl hubert.streidl@de.bosch.com Signed-off-by: Mark Jonas mark.jonas@de.bosch.com Reviewed-by: Wolfram Sang wsa+renesas@sang-engineering.com Signed-off-by: Lee Jones lee.jones@linaro.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/mfd/da9063-i2c.c | 10 ++++++++++ include/linux/mfd/da9063/registers.h | 3 +++ 2 files changed, 13 insertions(+)
diff --git a/drivers/mfd/da9063-i2c.c b/drivers/mfd/da9063-i2c.c index 3781d0bb7786..783a14af18e2 100644 --- a/drivers/mfd/da9063-i2c.c +++ b/drivers/mfd/da9063-i2c.c @@ -442,6 +442,16 @@ static int da9063_i2c_probe(struct i2c_client *i2c, return ret; }
+ /* If SMBus is not available and only I2C is possible, enter I2C mode */ + if (i2c_check_functionality(i2c->adapter, I2C_FUNC_I2C)) { + ret = regmap_clear_bits(da9063->regmap, DA9063_REG_CONFIG_J, + DA9063_TWOWIRE_TO); + if (ret < 0) { + dev_err(da9063->dev, "Failed to set Two-Wire Bus Mode.\n"); + return -EIO; + } + } + return da9063_device_init(da9063, i2c->irq); }
diff --git a/include/linux/mfd/da9063/registers.h b/include/linux/mfd/da9063/registers.h index 1dbabf1b3cb8..6e0f66a2e727 100644 --- a/include/linux/mfd/da9063/registers.h +++ b/include/linux/mfd/da9063/registers.h @@ -1037,6 +1037,9 @@ #define DA9063_NONKEY_PIN_AUTODOWN 0x02 #define DA9063_NONKEY_PIN_AUTOFLPRT 0x03
+/* DA9063_REG_CONFIG_J (addr=0x10F) */ +#define DA9063_TWOWIRE_TO 0x40 + /* DA9063_REG_MON_REG_5 (addr=0x116) */ #define DA9063_MON_A8_IDX_MASK 0x07 #define DA9063_MON_A8_IDX_NONE 0x00