On 2018-07-11 00:24, Wolfram Sang wrote:
> Some IP cores have an internal 'bus free' logic which may be more
> advanced than just checking if SDA is high. Add a separate callback to
> get this status. Filling it is optional.
>
> Signed-off-by: Wolfram Sang <[email protected]>
> ---
> drivers/i2c/i2c-core-base.c | 27 +++++++++++++++++++++++----
> include/linux/i2c.h | 3 +++
> 2 files changed, 26 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
> index c7995efd58ea..59f8dfc5be36 100644
> --- a/drivers/i2c/i2c-core-base.c
> +++ b/drivers/i2c/i2c-core-base.c
> @@ -158,6 +158,22 @@ static void set_sda_gpio_value(struct i2c_adapter *adap,
> int val)
> gpiod_set_value_cansleep(adap->bus_recovery_info->sda_gpiod, val);
> }
>
> +static int i2c_generic_bus_free(struct i2c_adapter *adap)
> +{
> + struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;
> + int ret = -EOPNOTSUPP;
> +
> + if (bri->get_bus_free)
> + ret = bri->get_bus_free(adap);
> + else if (bri->get_sda)
> + ret = bri->get_sda(adap);
> +
> + if (ret < 0)
> + return ret;
> +
> + return ret ? 0 : -EBUSY;
> +}
Hmmm, the name i2c_generic_bus_free suggests that scl should also be checked,
because the *bus* isn't really free unless both lines are high? No? Or, maybe
just rename to i2c_generic_sda_free (or something)?
But that's of course just a nit...
More importantly, isn't a ->get_bus_free implementation a sufficient requirement
for recovery? I.e. even if both ->get_sda and ->set_sda are missing?
Cheers,
Peter
> +
> /*
> * We are generating clock pulses. ndelay() determines durating of clk
> pulses.
> * We will generate clock with rate 100 KHz and so duration of both clock
> levels
> @@ -169,7 +185,7 @@ static void set_sda_gpio_value(struct i2c_adapter *adap,
> int val)
> int i2c_generic_scl_recovery(struct i2c_adapter *adap)
> {
> struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;
> - int i = 0, val = 1, ret = 0;
> + int i = 0, val = 1, ret;
>
> if (bri->prepare_recovery)
> bri->prepare_recovery(adap);
> @@ -207,14 +223,17 @@ int i2c_generic_scl_recovery(struct i2c_adapter *adap)
> bri->set_sda(adap, val);
> ndelay(RECOVERY_NDELAY / 2);
>
> - /* Break if SDA is high */
> - if (val && bri->get_sda) {
> - ret = bri->get_sda(adap) ? 0 : -EBUSY;
> + if (val) {
> + ret = i2c_generic_bus_free(adap);
> if (ret == 0)
> break;
> }
> }
>
> + /* If we can't check bus status, assume recovery worked */
> + if (ret == -EOPNOTSUPP)
> + ret = 0;
> +
> if (bri->unprepare_recovery)
> bri->unprepare_recovery(adap);
>
> diff --git a/include/linux/i2c.h b/include/linux/i2c.h
> index 9d1818c56775..60e224428a85 100644
> --- a/include/linux/i2c.h
> +++ b/include/linux/i2c.h
> @@ -587,6 +587,8 @@ struct i2c_timings {
> * @set_sda: This sets/clears the SDA line. This or get_sda() is mandatory
> for
> * generic SCL recovery. Populated internally, if sda_gpio is a valid GPIO,
> * for generic GPIO recovery.
> + * @get_bus_free: Returns the bus free state as seen from the IP core in
> case it
> + * has a more complex internal logic than just reading SDA. Optional.
> * @prepare_recovery: This will be called before starting recovery. Platform
> may
> * configure padmux here for SDA/SCL line or something else they want.
> * @unprepare_recovery: This will be called after completing recovery.
> Platform
> @@ -601,6 +603,7 @@ struct i2c_bus_recovery_info {
> void (*set_scl)(struct i2c_adapter *adap, int val);
> int (*get_sda)(struct i2c_adapter *adap);
> void (*set_sda)(struct i2c_adapter *adap, int val);
> + int (*get_bus_free)(struct i2c_adapter *adap);
>
> void (*prepare_recovery)(struct i2c_adapter *adap);
> void (*unprepare_recovery)(struct i2c_adapter *adap);
>
