[U-Boot] [PATCH 17/24] mxc_i2c: add bus recovery support

[Heiko Schocher]

Hello Troy,

On 22.06.2012 06:12, Troy Kisky wrote:
> Toggling the scl line 9 clocks is the standard
> way of returning a locked up bus to idle condition.
>
> Signed-off-by: Troy Kisky<troy.kisky at boundarydevices.com>
> ---
>   drivers/i2c/mxc_i2c.c |   26 ++++++++++++++++++++++++++
>   1 file changed, 26 insertions(+)
>
> diff --git a/drivers/i2c/mxc_i2c.c b/drivers/i2c/mxc_i2c.c
> index ec05798..339bb6f 100644
> --- a/drivers/i2c/mxc_i2c.c
> +++ b/drivers/i2c/mxc_i2c.c
> @@ -246,6 +246,8 @@ static int i2c_init_transfer_(struct mxc_i2c_regs *i2c_regs,
>   	return 0;
>   }
>
> +static void toggle_i2c(void *i2c_regs);
> +
>   static int i2c_init_transfer(struct mxc_i2c_regs *i2c_regs,
>   		uchar chip, uint addr, int alen)
>   {
> @@ -264,6 +266,7 @@ static int i2c_init_transfer(struct mxc_i2c_regs *i2c_regs,
>   		if (ret != -ERESTART)
>   			writeb(0,&i2c_regs->i2cr);	/* Disable controller */
>   		udelay(100);
> +		toggle_i2c(i2c_regs);
>   	}
>   	printf("%s: give up i2c_regs=%p\n", __func__, i2c_regs);
>   	return ret;
> @@ -381,6 +384,29 @@ void *get_base(void)
>   #endif
>   }
>
> +static struct i2c_parms *i2c_get_parms(void *base)
> +{
> +	int i = 0;
> +	struct i2c_parms *p = g_parms;
> +	while (i<  ARRAY_SIZE(g_parms)) {
> +		if (p->base == base)
> +			return p;
> +		p++;
> +		i++;
> +	}
> +	printf("Invalid I2C base: %p\n", base);
> +	return NULL;
> +}
> +
> +static void toggle_i2c(void *base)
> +{
> +	struct i2c_parms *p = i2c_get_parms(base);
> +	if (!p)
> +		return;
> +	if (p->toggle_fn)
> +		p->toggle_fn(p->toggle_data);
> +}
> +
>   int i2c_read(uchar chip, uint addr, int alen, uchar *buf, int len)
>   {
>   	return bus_i2c_read(get_base(), chip, addr, alen, buf, len);

Hmm.. why you cannot use the CONFIG_SYS_I2C_INIT_BOARD and i2c_init_board()
for unblocking the i2c bus? And where is the function, which really
toggles the SCL pin, as you described in the commit message?

bye,
Heiko
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