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.