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authorPeter Griffin <peter.griffin@linaro.org>2016-05-11 19:21:59 +0300
committerWolfram Sang <wsa@the-dreams.de>2016-05-13 13:40:15 +0300
commit40027b2fffc2dcef20080847b0913d210ef3ced0 (patch)
tree42b1372c3379cd0ad2cb1052ef25e024f68d4db7 /drivers/i2c
parent3a9ddaf4dca87f86f70b88d7710da20abfc9aca1 (diff)
downloadlinux-40027b2fffc2dcef20080847b0913d210ef3ced0.tar.xz
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')
-rw-r--r--drivers/i2c/busses/i2c-st.c45
1 files changed, 44 insertions, 1 deletions
diff --git a/drivers/i2c/busses/i2c-st.c b/drivers/i2c/busses/i2c-st.c
index b3c182fea165..944ec4205084 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;