[PATCH 1/4] ARM: shmobile: r8a73a4: safeguard against wrong clk_set_rate() uses

[Simon Horman]

On Fri, Jun 21, 2013 at 09:10:35AM +0200, Guennadi Liakhovetski wrote:
> clk_set_rate() should only be called with exact rates, returned by
> clk_round_rate(). However, it is still good to verify, that the value,
> passed to clock's .set_rate() method is at least valid. This patch adds
> such a check for the Z-clock on r8a73a4.
> 
> Signed-off-by: Guennadi Liakhovetski <g.liakhovetski+renesas at gmail.com>

Thanks, I have queued this up for v3.12 in the soc branch.

> ---
>  arch/arm/mach-shmobile/clock-r8a73a4.c |   14 +++++++++++++-
>  1 files changed, 13 insertions(+), 1 deletions(-)
> 
> diff --git a/arch/arm/mach-shmobile/clock-r8a73a4.c b/arch/arm/mach-shmobile/clock-r8a73a4.c
> index eb42740..cbf9852 100644
> --- a/arch/arm/mach-shmobile/clock-r8a73a4.c
> +++ b/arch/arm/mach-shmobile/clock-r8a73a4.c
> @@ -225,16 +225,28 @@ static int zclk_set_rate(struct clk *clk, unsigned long rate)
>  		goto done;
>  	}
>  
> -	frqcrc = clk->mapped_reg + (FRQCRC - (u32)clk->enable_reg);
> +	/*
> +	 * Users are supposed to first call clk_set_rate() only with
> +	 * clk_round_rate() results. So, we don't fix wrong rates here, but
> +	 * guard against them anyway
> +	 */
>  
>  	p_rate = clk_get_rate(clk->parent);
>  	if (rate == p_rate) {
>  		val = 0;
>  	} else {
>  		step = DIV_ROUND_CLOSEST(p_rate, 32);
> +
> +		if (rate > p_rate || rate < step) {
> +			ret = -EINVAL;
> +			goto done;
> +		}
> +
>  		val = 32 - rate / step;
>  	}
>  
> +	frqcrc = clk->mapped_reg + (FRQCRC - (u32)clk->enable_reg);
> +
>  	iowrite32((ioread32(frqcrc) & ~(clk->div_mask << clk->enable_bit)) |
>  		  (val << clk->enable_bit), frqcrc);
>  
> -- 
> 1.7.2.5
> 
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