i2c: exynos5: simplify timings calculation

Instead of using cryptic loop direct calculation of timings
can be used.

Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Tested-by: Javier Martinez Canillas <javier@osg.samsung.com>
Reviewed-by: Andi Shyti <andi.shyti@samsung.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

diff --git a/drivers/i2c/busses/i2c-exynos5.c b/drivers/i2c/busses/i2c-exynos5.c
index 736a824..5f24c3e 100644 (file)
--- a/drivers/i2c/busses/i2c-exynos5.c
+++ b/drivers/i2c/busses/i2c-exynos5.c
@@ -292,9 +292,9 @@ static int exynos5_i2c_set_timing(struct exynos5_i2c *i2c, int mode)
        unsigned int t_sr_release;
        unsigned int t_ftl_cycle;
        unsigned int clkin = clk_get_rate(i2c->clk);
-       unsigned int div, utemp0 = 0, utemp1 = 0, clk_cycle;
        unsigned int op_clk = (mode == HSI2C_HIGH_SPD) ?
                                i2c->hs_clock : i2c->fs_clock;
+       int div, clk_cycle, temp;
 
        /*
         * In case of HSI2C controller in Exynos5 series
@@ -305,33 +305,21 @@ static int exynos5_i2c_set_timing(struct exynos5_i2c *i2c, int mode)
         * FPCLK / FI2C =
         * (CLK_DIV + 1) * (TSCLK_L + TSCLK_H + 2) + 8 + FLT_CYCLE
         *
-        * utemp0 = (CLK_DIV + 1) * (TSCLK_L + TSCLK_H + 2)
-        * utemp1 = (TSCLK_L + TSCLK_H + 2)
+        * clk_cycle := TSCLK_L + TSCLK_H
+        * temp := (CLK_DIV + 1) * (clk_cycle + 2)
+        *
+        * Constraints: 4 <= temp, 0 <= CLK_DIV < 256, 2 <= clk_cycle <= 510
+        *
         */
        t_ftl_cycle = (readl(i2c->regs + HSI2C_CONF) >> 16) & 0x7;
-       utemp0 = (clkin / op_clk) - 8;
-
-       if (i2c->variant->hw == HSI2C_EXYNOS7)
-               utemp0 -= t_ftl_cycle;
-       else
-               utemp0 -= 2 * t_ftl_cycle;
-
-       /* CLK_DIV max is 256 */
-       for (div = 0; div < 256; div++) {
-               utemp1 = utemp0 / (div + 1);
-
-               /*
-                * SCL_L and SCL_H each has max value of 255
-                * Hence, For the clk_cycle to the have right value
-                * utemp1 has to be less then 512 and more than 4.
-                */
-               if ((utemp1 < 512) && (utemp1 > 4)) {
-                       clk_cycle = utemp1 - 2;
-                       break;
-               } else if (div == 255) {
-                       dev_warn(i2c->dev, "Failed to calculate divisor");
-                       return -EINVAL;
-               }
+       temp = clkin / op_clk - 8 - t_ftl_cycle;
+       if (i2c->variant->hw != HSI2C_EXYNOS7)
+               temp -= t_ftl_cycle;
+       div = temp / 512;
+       clk_cycle = temp / (div + 1) - 2;
+       if (temp < 4 || div >= 256 || clk_cycle < 2) {
+               dev_warn(i2c->dev, "Failed to calculate divisor");
+               return -EINVAL;
        }
 
        t_scl_l = clk_cycle / 2;