mmc: tmio: refactor CLK_CTL bit calculation

for (clk = 0x80000080; new_clock >= (clock << 1); clk >>= 1)
          clock <<= 1;

... is too tricky, hence I replaced with

  roundup_pow_of_two(divisor) >> 2

'(clk >> 22) & 0x1' is the bit test for the 1/1 divisor, but
it is not clear.  'divisor <= 1' is easier to understand.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

diff --git a/drivers/mmc/host/tmio_mmc.c b/drivers/mmc/host/tmio_mmc.c
index 09bb104..0ae9ba1 100644 (file)
--- a/drivers/mmc/host/tmio_mmc.c
+++ b/drivers/mmc/host/tmio_mmc.c
@@ -45,19 +45,27 @@ static void tmio_mmc_clk_stop(struct tmio_mmc_host *host)
 static void tmio_mmc_set_clock(struct tmio_mmc_host *host,
                               unsigned int new_clock)
 {
-       u32 clk = 0, clock;
+       unsigned int clock, divisor;
+       u32 clk = 0;
+       int clk_sel;
 
        if (new_clock == 0) {
                tmio_mmc_clk_stop(host);
                return;
        }
 
-       clock = host->mmc->f_min;
+       divisor = host->pdata->hclk / new_clock;
 
-       for (clk = 0x80000080; new_clock >= (clock << 1); clk >>= 1)
-               clock <<= 1;
+       if (divisor <= 1) {
+               clk_sel = 1;
+               clk = 0;
+       } else {
+               clk_sel = 0;
+               /* bit7 set: 1/512, ... bit0 set:1/4, all bits clear: 1/2 */
+               clk = roundup_pow_of_two(divisor) >> 2;
+       }
 
-       host->pdata->set_clk_div(host->pdev, (clk >> 22) & 1);
+       host->pdata->set_clk_div(host->pdev, clk_sel);
 
        sd_ctrl_write16(host, CTL_SD_CARD_CLK_CTL, ~CLK_CTL_SCLKEN &
                        sd_ctrl_read16(host, CTL_SD_CARD_CLK_CTL));