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i2c: i2c-stm32f7: Implement I2C release mechanism 

Feature prevents I2C lock-ups. Mechanism resets I2C state machine
and releases SCL/SDA signals but preserves I2C registers.

Signed-off-by: Pierre-Yves MORDRET <pierre-yves.mordret@st.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
This commit is contained in:
Pierre-Yves MORDRET 2018-04-11 15:24:58 +02:00 committed by Wolfram Sang
parent 7ecc8cfde5
commit 562de4ff4c
1 changed files with 24 additions and 3 deletions
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27
drivers/i2c/busses/i2c-stm32f7.c
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@ -718,6 +718,20 @@ static void stm32f7_i2c_smbus_reload(struct stm32f7_i2c_dev *i2c_dev)
writel_relaxed(cr2, i2c_dev->base + STM32F7_I2C_CR2);
}
static int stm32f7_i2c_release_bus(struct i2c_adapter *i2c_adap)
{
struct stm32f7_i2c_dev *i2c_dev = i2c_get_adapdata(i2c_adap);
dev_info(i2c_dev->dev, "Trying to recover bus\n");
stm32f7_i2c_clr_bits(i2c_dev->base + STM32F7_I2C_CR1,
STM32F7_I2C_CR1_PE);
stm32f7_i2c_hw_config(i2c_dev);
return 0;
}
static int stm32f7_i2c_wait_free_bus(struct stm32f7_i2c_dev *i2c_dev)
{
u32 status;
@ -727,12 +741,18 @@ static int stm32f7_i2c_wait_free_bus(struct stm32f7_i2c_dev *i2c_dev)
status,
!(status & STM32F7_I2C_ISR_BUSY),
10, 1000);
if (!ret)
return 0;
dev_info(i2c_dev->dev, "bus busy\n");
ret = stm32f7_i2c_release_bus(&i2c_dev->adap);
if (ret) {
dev_dbg(i2c_dev->dev, "bus busy\n");
ret = -EBUSY;
dev_err(i2c_dev->dev, "Failed to recover the bus (%d)\n", ret);
return ret;
}
return ret;
return -EBUSY;
}
static void stm32f7_i2c_xfer_msg(struct stm32f7_i2c_dev *i2c_dev,
@ -1474,6 +1494,7 @@ static irqreturn_t stm32f7_i2c_isr_error(int irq, void *data)
if (status & STM32F7_I2C_ISR_BERR) {
dev_err(dev, "<%s>: Bus error\n", __func__);
writel_relaxed(STM32F7_I2C_ICR_BERRCF, base + STM32F7_I2C_ICR);
stm32f7_i2c_release_bus(&i2c_dev->adap);
f7_msg->result = -EIO;
}