Subject: [PATCH] clk: debugfs add clk_rate_fops with DEBUG

From: [email-masked] (Mike Turquette)
Date: Mon, 07 Oct 2013 14:29:04 -0700

Quoting Zhangfei Gao (2013-08-18 22:34:17)
> clk_rate_fops is added to debug
> 1. set_rate (e.g. PLL)
> 2. Choose mux parent, since mux could choose parent accordingly when set_rate.
> 
> Causion: set_rate can be called directly from user space
> 
> Example:
> sfc_mux have two parents: 24M and 200M
> 
> cat clk_summary
>    clock                        enable_cnt  prepare_cnt  rate
> ---------------------------------------------------------------------
>  osc24mhz                       3           3            24000000
>     bpll_fout3                  0           0            200000000
>        sfc_mux                  0           0            200000000
>           sfc                   0           0            200000000
> 
> cat osc24mhz/bpll/bpll_fout3/sfc_mux/sfc/clk_rate
> 200000000
> 
> echo 24000000 >  osc24mhz/bpll/bpll_fout3/sfc_mux/sfc/clk_rate
> cat clk_summary
>    clock                        enable_cnt  prepare_cnt  rate
> ---------------------------------------------------------------------
>  osc24mhz                       3           3            24000000
>     sfc_mux                     0           0            24000000
>        sfc                      0           0            24000000
>     bpll_fout3                  0           0            200000000
> 
> cat osc24mhz/sfc_mux/sfc/clk_rate
> 24000000
> 
> Signed-off-by: Zhangfei Gao <[email-masked]>

Thanks for the patch. It is trivial enough where I think we can leave it
on the list and let developers apply it if they need it for debug. I
don't want to merge it since it exposes hardware control to userspace
and could be abused in a way that could damage a device.

Regards,
Mike

> ---
>  drivers/clk/clk.c |   34 ++++++++++++++++++++++++++++++++++
>  1 file changed, 34 insertions(+)
> 
> diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
> index 373cd54..6b582f7 100644
> --- a/drivers/clk/clk.c
> +++ b/drivers/clk/clk.c
> @@ -226,6 +226,35 @@ static const struct file_operations clk_dump_fops = {
>         .release        = single_release,
>  };
>  
> +#ifdef DEBUG
> +static int clk_rate_fops_get(void *data, u64 *rate)
> +{
> +       struct clk *clk = data;
> +
> +       *rate = clk->rate;
> +
> +       return 0;
> +};
> +
> +static int clk_rate_fops_set(void *data, u64 rate)
> +{
> +       struct clk *clk = data;
> +       int ret = 0;
> +
> +       ret = clk_prepare_enable(clk);
> +       if (ret)
> +               goto out;
> +       clk_set_rate(clk, rate);
> +       clk_disable_unprepare(clk);
> +
> +out:
> +       return ret;
> +};
> +
> +DEFINE_SIMPLE_ATTRIBUTE(clk_rate_fops, clk_rate_fops_get,
> +                       clk_rate_fops_set, "%llu\n");
> +#endif
> +
>  /* caller must hold prepare_lock */
>  static int clk_debug_create_one(struct clk *clk, struct dentry *pdentry)
>  {
> @@ -243,8 +272,13 @@ static int clk_debug_create_one(struct clk *clk, struct dentry *pdentry)
>  
>         clk->dentry = d;
>  
> +#ifdef DEBUG
> +       d = debugfs_create_file("clk_rate", S_IWUSR | S_IRUGO, clk->dentry,
> +                               clk, &clk_rate_fops);
> +#else
>         d = debugfs_create_u32("clk_rate", S_IRUGO, clk->dentry,
>                         (u32 *)&clk->rate);
> +#endif
>         if (!d)
>                 goto err_out;
>  
> -- 
> 1.7.9.5