On 1/27/20 7:40 AM, Heiko Schocher wrote:

Hello Marek,

Am 24.01.2020 um 19:12 schrieb Marek Vasut:

...

Add custom deblock dequence for the I2C bus, needed on some devices. This sequence is issued once, when probing the driver, and is controlled by DT property, "i2c-gpio,deblock".

Signed-off-by: Marek Vasut marex@denx.de

drivers/i2c/i2c-gpio.c | 67 ++++++++++++++++++++++++++++++++++++++++++   1 file changed, 67 insertions(+)

diff --git a/drivers/i2c/i2c-gpio.c b/drivers/i2c/i2c-gpio.c index 4e8fa21473..46975ef5c8 100644 --- a/drivers/i2c/i2c-gpio.c +++ b/drivers/i2c/i2c-gpio.c @@ -39,6 +39,11 @@ static int i2c_gpio_sda_get(struct gpio_desc *sda)       return dm_gpio_get_value(sda);   }   +static int i2c_gpio_scl_get(struct gpio_desc *scl) +{ +    return dm_gpio_get_value(scl); +}

static void i2c_gpio_sda_set(struct gpio_desc *sda, int bit)   {       if (bit) @@ -305,6 +310,67 @@ static int i2c_gpio_set_bus_speed(struct udevice *dev, unsigned int speed_hz)       return 0;   }   +/*

• • I2C is a synchronous protocol and resets of the processor in the

middle

• • of an access can block the I2C Bus until a powerdown of the full

unit is

• • done. This function toggles the SCL until the SCL and SCA line are
• • released, but max. 16 times, after this a I2C start-sequence is sent.
• • This I2C Deblocking mechanism was developed by Keymile in association
• • with Anatech and Atmel in 1998.
• */

+static void i2c_gpio_make_abort(struct udevice *dev) +{ +    struct i2c_gpio_bus *bus = dev_get_priv(dev); +    struct gpio_desc *scl = &bus->gpios[PIN_SCL]; +    struct gpio_desc *sda = &bus->gpios[PIN_SDA]; +    int scl_state = 0; +    int sda_state = 0; +    int i = 0; +    int ret = 0;

+#define DELAY_ABORT_SEQ    62    /* @200kHz 9 clocks = 44us, 62us is ok */

+    i2c_gpio_scl_set(scl, 1);

+    if (!i2c_gpio_sda_get(sda)) { +        ret = -1; +        for (i = 0; i < 16; i++) { +            i2c_gpio_scl_set(scl, 0); +            udelay(DELAY_ABORT_SEQ); +            i2c_gpio_scl_set(scl, 1); +            udelay(DELAY_ABORT_SEQ); +            scl_state = i2c_gpio_scl_get(scl); +            sda_state = i2c_gpio_sda_get(sda); +            if (scl_state && sda_state) { +                ret = 0; +                break; +            } +        } +    }

+    if (!ret) { +        for (i = 0; i < 5; i++) { +            i2c_gpio_send_start(scl, sda, 2 * bus->udelay); +            i2c_gpio_scl_set(scl, 0); +        } +    }

+    /* respect stop setup time */ +    udelay(DELAY_ABORT_SEQ); +    i2c_gpio_scl_set(scl, 1); +    udelay(DELAY_ABORT_SEQ); +    i2c_gpio_sda_set(sda, 1); +    i2c_gpio_sda_get(sda); +}

+static int i2c_gpio_drv_probe(struct udevice *dev) +{ +    if (dev_read_bool(dev, "i2c-gpio,deblock")) +        i2c_gpio_make_abort(dev);

+    return 0; +}

static int i2c_gpio_ofdata_to_platdata(struct udevice *dev)   {       struct i2c_gpio_bus *bus = dev_get_priv(dev); @@ -341,6 +407,7 @@ U_BOOT_DRIVER(i2c_gpio) = {       .name    = "i2c-gpio",       .id    = UCLASS_I2C,       .of_match = i2c_gpio_ids, +    .probe    = i2c_gpio_drv_probe,       .ofdata_to_platdata = i2c_gpio_ofdata_to_platdata,       .priv_auto_alloc_size = sizeof(struct i2c_gpio_bus),       .ops    = &i2c_gpio_ops,

Hmm.. why do you add this into the probe function and do not add it to:

https://gitlab.denx.de/u-boot/u-boot/blob/master/include/i2c.h#L382

Because I wasn't aware of this callback.

which is called from: https://gitlab.denx.de/u-boot/u-boot/blob/master/drivers/i2c/i2c-uclass.c#L5...

Ok, i2c_deblock() currently is only used from do_i2c_reset(), but may it is worth to adapt drivers/i2c-core/i2c-uclass.c to call the deblock sequence also from i2c_pre_probe()?

May dependend on your proposed DT property "i2c-gpio,deblock" ?

But please update also the documentation in

u-boot:/doc/device-tree-bindings/i2c/i2c-gpio.txt

or if we go the more generic way:

u-boot:/doc/device-tree-bindings/i2c/i2c.txt

Thanks!

BTW: May it makes sense to adapt: https://gitlab.denx.de/u-boot/u-boot/blob/master/drivers/i2c/i2c-uclass.c#L5...

I need to take a look at this one.