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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>
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1 changed files with 44 additions and 1 deletions
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@ -337,10 +337,42 @@ static void st_i2c_hw_config(struct st_i2c_dev *i2c_dev)
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writel_relaxed(val, i2c_dev->base + SSC_NOISE_SUPP_WIDTH_DATAOUT);
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}
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static int st_i2c_recover_bus(struct i2c_adapter *i2c_adap)
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{
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struct st_i2c_dev *i2c_dev = i2c_get_adapdata(i2c_adap);
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u32 ctl;
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dev_dbg(i2c_dev->dev, "Trying to recover bus\n");
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/*
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* SSP IP is dual role SPI/I2C to generate 9 clock pulses
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* we switch to SPI node, 9 bit words and write a 0. This
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* has been validate with a oscilloscope and is easier
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* than switching to GPIO mode.
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*/
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/* Disable interrupts */
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writel_relaxed(0, i2c_dev->base + SSC_IEN);
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st_i2c_hw_config(i2c_dev);
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ctl = SSC_CTL_EN | SSC_CTL_MS | SSC_CTL_EN_RX_FIFO | SSC_CTL_EN_TX_FIFO;
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st_i2c_set_bits(i2c_dev->base + SSC_CTL, ctl);
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st_i2c_clr_bits(i2c_dev->base + SSC_I2C, SSC_I2C_I2CM);
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usleep_range(8000, 10000);
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writel_relaxed(0, i2c_dev->base + SSC_TBUF);
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usleep_range(2000, 4000);
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st_i2c_set_bits(i2c_dev->base + SSC_I2C, SSC_I2C_I2CM);
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return 0;
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}
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static int st_i2c_wait_free_bus(struct st_i2c_dev *i2c_dev)
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{
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u32 sta;
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int i;
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int i, ret;
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for (i = 0; i < 10; i++) {
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sta = readl_relaxed(i2c_dev->base + SSC_STA);
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@ -352,6 +384,12 @@ static int st_i2c_wait_free_bus(struct st_i2c_dev *i2c_dev)
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dev_err(i2c_dev->dev, "bus not free (status = 0x%08x)\n", sta);
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ret = i2c_recover_bus(&i2c_dev->adap);
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if (ret) {
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dev_err(i2c_dev->dev, "Failed to recover the bus (%d)\n", ret);
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return ret;
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}
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return -EBUSY;
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}
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@ -743,6 +781,10 @@ static struct i2c_algorithm st_i2c_algo = {
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.functionality = st_i2c_func,
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};
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static struct i2c_bus_recovery_info st_i2c_recovery_info = {
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.recover_bus = st_i2c_recover_bus,
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};
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static int st_i2c_of_get_deglitch(struct device_node *np,
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struct st_i2c_dev *i2c_dev)
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{
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@ -825,6 +867,7 @@ static int st_i2c_probe(struct platform_device *pdev)
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adap->timeout = 2 * HZ;
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adap->retries = 0;
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adap->algo = &st_i2c_algo;
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adap->bus_recovery_info = &st_i2c_recovery_info;
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adap->dev.parent = &pdev->dev;
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adap->dev.of_node = pdev->dev.of_node;
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