Subject: [PATCHv4 01/33] CLK: clkdev: add support for looking up clocks from DT

From: [email-masked] (Nishanth Menon)
Date: Tue, 30 Jul 2013 10:04:30 -0500

On 07/23/2013 02:19 AM, Tero Kristo wrote:
> clk_get_sys / clk_get can now find clocks from device-tree. If a DT clock
> is found, an entry is added to the clk_lookup list also for subsequent
> searches.
>
> Signed-off-by: Tero Kristo <[email-masked]>
> Cc: Russell King <[email-masked]>
> ---
>   drivers/clk/clkdev.c |   32 ++++++++++++++++++++++++++++++++
>   1 file changed, 32 insertions(+)
>
> diff --git a/drivers/clk/clkdev.c b/drivers/clk/clkdev.c
> index 442a313..e39f082 100644
> --- a/drivers/clk/clkdev.c
> +++ b/drivers/clk/clkdev.c
> @@ -93,6 +93,18 @@ struct clk *of_clk_get_by_name(struct device_node *np, const char *name)
>   EXPORT_SYMBOL(of_clk_get_by_name);
>   #endif
>
> +/**
> + * clkdev_add_nolock - add lookup entry for a clock
> + * @cl: pointer to new clock lookup entry
> + *
> + * Non-locking version, used internally by clk_find() to add DT based
> + * clock lookup entries.
> + */
> +static void clkdev_add_nolock(struct clk_lookup *cl)
> +{
> +	list_add_tail(&cl->node, &clocks);
> +}
> +
>   /*
>    * Find the correct struct clk for the device and connection ID.
>    * We do slightly fuzzy matching here:
> @@ -106,6 +118,9 @@ static struct clk_lookup *clk_find(const char *dev_id, const char *con_id)
>   {
>   	struct clk_lookup *p, *cl = NULL;
>   	int match, best_found = 0, best_possible = 0;
> +	struct device_node *node;
> +	struct clk *clk;
> +	struct of_phandle_args clkspec;
>
>   	if (dev_id)
>   		best_possible += 2;
> @@ -133,6 +148,23 @@ static struct clk_lookup *clk_find(const char *dev_id, const char *con_id)
>   				break;
>   		}
>   	}
> +
> +	if (cl)
> +		return cl;
> +
> +	/* If clock was not found, attempt to look-up from DT */
> +	node = of_find_node_by_name(NULL, con_id);
> +
> +	clkspec.np = node;
> +
> +	clk = of_clk_get_from_provider(&clkspec);
> +
> +	if (!IS_ERR(clk)) {
> +		/* We found a clock, add node to clkdev */
> +		cl = clkdev_alloc(clk, con_id, dev_id);

clkdev_alloc may return NULL depending on vclkdev_alloc in which case 
clkdev_add_nolock will crash trying to dereference it.

> +		clkdev_add_nolock(cl);
> +	}
> +
>   	return cl;
>   }

-- 
Regards,
Nishanth Menon