ARM: shmobile: r8a73a4: safeguard against wrong clk_set_rate() uses

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@gmail.com>
Acked-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>

diff --git a/arch/arm/mach-shmobile/clock-r8a73a4.c b/arch/arm/mach-shmobile/clock-r8a73a4.c
index 824789c26fb610d78b3b2c3d4844c95237a945bc..22f10ff40272251984ecead076495bf3c968bc42 100644 (file)
--- 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);