On 03/19/2018 10:36 AM, Phil Reid wrote:
> On 12/03/2018 18:53, Pierre-Yves MORDRET wrote:
>> 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@xxxxxx>
>> ---
>> Version history:
>> v1:
>> * Initial
>> ---
>> ---
>> drivers/i2c/busses/i2c-stm32f7.c | 32 +++++++++++++++++++++++++++++---
>> 1 file changed, 29 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/i2c/busses/i2c-stm32f7.c b/drivers/i2c/busses/i2c-stm32f7.c
>> index 69a2e5e..3808bc9 100644
>> --- a/drivers/i2c/busses/i2c-stm32f7.c
>> +++ b/drivers/i2c/busses/i2c-stm32f7.c
>> @@ -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_recover_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);
>
> This only "releases" the scl / sda on the stm32f7 end (outputs are hiz I guess).
> It doesn't trigger the scl clocking needed to recover a stuck device via i2c recovery
> from what I can see in the data sheet.
>
Correct. This mechanism resets the core IP and not the slave.
>
>> +
>> + stm32f7_i2c_hw_config(i2c_dev);
>
> Nothing in here either I think.
>
>
>> +
>> + 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 = i2c_recover_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,
>> @@ -1476,6 +1496,7 @@ 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);
>> + i2c_recover_bus(&i2c_dev->adap);
>> f7_msg->result = -EIO;
>> }
>>
>> @@ -1760,6 +1781,10 @@ static struct i2c_algorithm stm32f7_i2c_algo = {
>> .unreg_slave = stm32f7_i2c_unreg_slave,
>> };
>>
>> +static struct i2c_bus_recovery_info stm32f7_i2c_recovery_info = {
>> + .recover_bus = stm32f7_i2c_recover_bus,
>> +};
>> +
>> static int stm32f7_i2c_probe(struct platform_device *pdev)
>> {
>> struct device_node *np = pdev->dev.of_node;
>> @@ -1879,6 +1904,7 @@ static int stm32f7_i2c_probe(struct platform_device *pdev)
>> adap->algo = &stm32f7_i2c_algo;
>> adap->dev.parent = &pdev->dev;
>> adap->dev.of_node = pdev->dev.of_node;
>> + adap->bus_recovery_info = &stm32f7_i2c_recovery_info;
>>
>> init_completion(&i2c_dev->complete);
>>
>>
>
>
