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author | Peter Griffin <peter.griffin@linaro.org> | 2016-05-11 17:21:59 +0100 |
---|---|---|
committer | Wolfram Sang <wsa@the-dreams.de> | 2016-05-13 12:40:15 +0200 |
commit | 40027b2fffc2dcef20080847b0913d210ef3ced0 (patch) | |
tree | 42b1372c3379cd0ad2cb1052ef25e024f68d4db7 /drivers/i2c/busses | |
parent | 3a9ddaf4dca87f86f70b88d7710da20abfc9aca1 (diff) | |
download | op-kernel-dev-40027b2fffc2dcef20080847b0913d210ef3ced0.zip op-kernel-dev-40027b2fffc2dcef20080847b0913d210ef3ced0.tar.gz |
i2c: st: Implement bus clear
>From I2C specifications:
http://www.nxp.com/documents/user_manual/UM10204.pdf
Chapter 3.1.16, 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@st.com>
Signed-off-by: Peter Griffin <peter.griffin@linaro.org>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Diffstat (limited to 'drivers/i2c/busses')
-rw-r--r-- | drivers/i2c/busses/i2c-st.c | 45 |
1 files changed, 44 insertions, 1 deletions
diff --git a/drivers/i2c/busses/i2c-st.c b/drivers/i2c/busses/i2c-st.c index b3c182f..944ec420 100644 --- a/drivers/i2c/busses/i2c-st.c +++ b/drivers/i2c/busses/i2c-st.c @@ -337,10 +337,42 @@ static void st_i2c_hw_config(struct st_i2c_dev *i2c_dev) writel_relaxed(val, i2c_dev->base + SSC_NOISE_SUPP_WIDTH_DATAOUT); } +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_dbg(i2c_dev->dev, "Trying to recover bus\n"); + + /* + * SSP IP is dual role SPI/I2C to generate 9 clock pulses + * we switch to SPI node, 9 bit words and write a 0. This + * has been validate with a oscilloscope and is easier + * than switching to GPIO mode. + */ + + /* 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 +384,12 @@ 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; } @@ -743,6 +781,10 @@ 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, +}; + static int st_i2c_of_get_deglitch(struct device_node *np, struct st_i2c_dev *i2c_dev) { @@ -825,6 +867,7 @@ 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; |