>From I2C specification: http://www.nxp.com/documents/user_manual/UM10204.pdf Rev. 03 section 3.1.16 titled "Bus clear". When the i2c device held the SDA line low, the master should send 9 clocks pulses to try to recover. Signed-off-by: Frederic Pillon <frederic.pillon@xxxxxx> Signed-off-by: Peter Griffin <peter.griffin@xxxxxxxxxx> --- drivers/i2c/busses/i2c-st.c | 56 ++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 55 insertions(+), 1 deletion(-) diff --git a/drivers/i2c/busses/i2c-st.c b/drivers/i2c/busses/i2c-st.c index 6ee7715..37b0b34 100644 --- a/drivers/i2c/busses/i2c-st.c +++ b/drivers/i2c/busses/i2c-st.c @@ -337,10 +337,51 @@ static void st_i2c_hw_config(struct st_i2c_dev *i2c_dev) writel_relaxed(val, i2c_dev->base + SSC_NOISE_SUPP_WIDTH_DATAOUT); } +/* + * i2c bus recovery routines + * get_scl and set_scl must be defined to avoid the recover_bus field of + * i2c_bus_recovery_info to be overriden with NULL during the + * i2c_add_adapter call + */ + +static int st_i2c_get_scl(struct i2c_adapter *adap) +{ + return 0; +} + +static void st_i2c_set_scl(struct i2c_adapter *adap, int val) +{ +} + +static int st_i2c_recover_bus(struct i2c_adapter *i2c_adap) +{ + struct st_i2c_dev *i2c_dev = i2c_get_adapdata(i2c_adap); + u32 ctl; + + dev_err(i2c_dev->dev, "Trying to recover bus\n"); + + /* Disable interrupts */ + writel_relaxed(0, i2c_dev->base + SSC_IEN); + + st_i2c_hw_config(i2c_dev); + + ctl = SSC_CTL_EN | SSC_CTL_MS | SSC_CTL_EN_RX_FIFO | SSC_CTL_EN_TX_FIFO; + st_i2c_set_bits(i2c_dev->base + SSC_CTL, ctl); + + st_i2c_clr_bits(i2c_dev->base + SSC_I2C, SSC_I2C_I2CM); + usleep_range(8000, 10000); + + writel_relaxed(0, i2c_dev->base + SSC_TBUF); + usleep_range(2000, 4000); + st_i2c_set_bits(i2c_dev->base + SSC_I2C, SSC_I2C_I2CM); + + return 0; +} + static int st_i2c_wait_free_bus(struct st_i2c_dev *i2c_dev) { u32 sta; - int i; + int i, ret; for (i = 0; i < 10; i++) { sta = readl_relaxed(i2c_dev->base + SSC_STA); @@ -352,6 +393,12 @@ static int st_i2c_wait_free_bus(struct st_i2c_dev *i2c_dev) dev_err(i2c_dev->dev, "bus not free (status = 0x%08x)\n", sta); + ret = i2c_recover_bus(&i2c_dev->adap); + if (ret) { + dev_err(i2c_dev->dev, "Failed to recover the bus (%d)\n", ret); + return ret; + } + return -EBUSY; } @@ -744,6 +791,12 @@ static struct i2c_algorithm st_i2c_algo = { .functionality = st_i2c_func, }; +static struct i2c_bus_recovery_info st_i2c_recovery_info = { + .recover_bus = st_i2c_recover_bus, + .get_scl = st_i2c_get_scl, + .set_scl = st_i2c_set_scl, +}; + static int st_i2c_of_get_deglitch(struct device_node *np, struct st_i2c_dev *i2c_dev) { @@ -826,6 +879,7 @@ static int st_i2c_probe(struct platform_device *pdev) adap->timeout = 2 * HZ; adap->retries = 0; adap->algo = &st_i2c_algo; + adap->bus_recovery_info = &st_i2c_recovery_info; adap->dev.parent = &pdev->dev; adap->dev.of_node = pdev->dev.of_node; -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
