i2c: mediatek: send i2c master code at 400k

The speed of sending i2c master code in high-speed mode depends on
source clock, clock-div and TIMING register. The source clock and
clock-div of different SoC are not all the same. In order to send
i2c master code at 400k in high-speed mode, a appropriate value
should be set to TIMING register for a certain source clock and
clock-div.

Signed-off-by: Jun Gao <jun.gao@mediatek.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

diff --git a/drivers/i2c/busses/i2c-mt65xx.c b/drivers/i2c/busses/i2c-mt65xx.c
index 45d61714c81bd2cfdec86e7f95ffaaa11abc5565..9bedf0bf2c4dc958500414ea3c07fa5d928ddce4 100644 (file)
--- a/drivers/i2c/busses/i2c-mt65xx.c
+++ b/drivers/i2c/busses/i2c-mt65xx.c
@@ -50,7 +50,6 @@
 #define I2C_FS_START_CON               0x1800
 #define I2C_TIME_CLR_VALUE             0x0000
 #define I2C_TIME_DEFAULT_VALUE         0x0003
-#define I2C_FS_TIME_INIT_VALUE         0x1303
 #define I2C_WRRD_TRANAC_VALUE          0x0002
 #define I2C_RD_TRANAC_VALUE            0x0001
 
@@ -154,6 +153,7 @@ struct mtk_i2c {
        bool use_push_pull;             /* IO config push-pull mode */
 
        u16 irq_stat;                   /* interrupt status */
+       unsigned int clk_src_div;
        unsigned int speed_hz;          /* The speed in transfer */
        enum mtk_trans_op op;
        u16 timing_reg;
@@ -285,23 +285,20 @@ static void mtk_i2c_init_hw(struct mtk_i2c *i2c)
  * less than or equal to i2c->speed_hz. The calculation try to get
  * sample_cnt and step_cn
  */
-static int mtk_i2c_set_speed(struct mtk_i2c *i2c, unsigned int parent_clk,
-                            unsigned int clock_div)
+static int mtk_i2c_calculate_speed(struct mtk_i2c *i2c, unsigned int clk_src,
+                                  unsigned int target_speed,
+                                  unsigned int *timing_step_cnt,
+                                  unsigned int *timing_sample_cnt)
 {
-       unsigned int clk_src;
        unsigned int step_cnt;
        unsigned int sample_cnt;
        unsigned int max_step_cnt;
-       unsigned int target_speed;
        unsigned int base_sample_cnt = MAX_SAMPLE_CNT_DIV;
        unsigned int base_step_cnt;
        unsigned int opt_div;
        unsigned int best_mul;
        unsigned int cnt_mul;
 
-       clk_src = parent_clk / clock_div;
-       target_speed = i2c->speed_hz;
-
        if (target_speed > MAX_HS_MODE_SPEED)
                target_speed = MAX_HS_MODE_SPEED;
 
@@ -347,16 +344,48 @@ static int mtk_i2c_set_speed(struct mtk_i2c *i2c, unsigned int parent_clk,
                return -EINVAL;
        }
 
-       step_cnt--;
-       sample_cnt--;
+       *timing_step_cnt = step_cnt - 1;
+       *timing_sample_cnt = sample_cnt - 1;
+
+       return 0;
+}
+
+static int mtk_i2c_set_speed(struct mtk_i2c *i2c, unsigned int parent_clk)
+{
+       unsigned int clk_src;
+       unsigned int step_cnt;
+       unsigned int sample_cnt;
+       unsigned int target_speed;
+       int ret;
+
+       clk_src = parent_clk / i2c->clk_src_div;
+       target_speed = i2c->speed_hz;
 
        if (target_speed > MAX_FS_MODE_SPEED) {
+               /* Set master code speed register */
+               ret = mtk_i2c_calculate_speed(i2c, clk_src, MAX_FS_MODE_SPEED,
+                                             &step_cnt, &sample_cnt);
+               if (ret < 0)
+                       return ret;
+
+               i2c->timing_reg = (sample_cnt << 8) | step_cnt;
+
                /* Set the high speed mode register */
-               i2c->timing_reg = I2C_FS_TIME_INIT_VALUE;
+               ret = mtk_i2c_calculate_speed(i2c, clk_src, target_speed,
+                                             &step_cnt, &sample_cnt);
+               if (ret < 0)
+                       return ret;
+
                i2c->high_speed_reg = I2C_TIME_DEFAULT_VALUE |
                        (sample_cnt << 12) | (step_cnt << 8);
        } else {
-               i2c->timing_reg = (sample_cnt << 8) | (step_cnt << 0);
+               ret = mtk_i2c_calculate_speed(i2c, clk_src, target_speed,
+                                             &step_cnt, &sample_cnt);
+               if (ret < 0)
+                       return ret;
+
+               i2c->timing_reg = (sample_cnt << 8) | step_cnt;
+
                /* Disable the high speed transaction */
                i2c->high_speed_reg = I2C_TIME_CLR_VALUE;
        }
@@ -647,8 +676,7 @@ static const struct i2c_algorithm mtk_i2c_algorithm = {
        .functionality = mtk_i2c_functionality,
 };
 
-static int mtk_i2c_parse_dt(struct device_node *np, struct mtk_i2c *i2c,
-                           unsigned int *clk_src_div)
+static int mtk_i2c_parse_dt(struct device_node *np, struct mtk_i2c *i2c)
 {
        int ret;
 
@@ -656,11 +684,11 @@ static int mtk_i2c_parse_dt(struct device_node *np, struct mtk_i2c *i2c,
        if (ret < 0)
                i2c->speed_hz = I2C_DEFAULT_SPEED;
 
-       ret = of_property_read_u32(np, "clock-div", clk_src_div);
+       ret = of_property_read_u32(np, "clock-div", &i2c->clk_src_div);
        if (ret < 0)
                return ret;
 
-       if (*clk_src_div == 0)
+       if (i2c->clk_src_div == 0)
                return -EINVAL;
 
        i2c->have_pmic = of_property_read_bool(np, "mediatek,have-pmic");
@@ -676,7 +704,6 @@ static int mtk_i2c_probe(struct platform_device *pdev)
        int ret = 0;
        struct mtk_i2c *i2c;
        struct clk *clk;
-       unsigned int clk_src_div;
        struct resource *res;
        int irq;
 
@@ -684,7 +711,7 @@ static int mtk_i2c_probe(struct platform_device *pdev)
        if (!i2c)
                return -ENOMEM;
 
-       ret = mtk_i2c_parse_dt(pdev->dev.of_node, i2c, &clk_src_div);
+       ret = mtk_i2c_parse_dt(pdev->dev.of_node, i2c);
        if (ret)
                return -EINVAL;
 
@@ -745,7 +772,7 @@ static int mtk_i2c_probe(struct platform_device *pdev)
 
        strlcpy(i2c->adap.name, I2C_DRV_NAME, sizeof(i2c->adap.name));
 
-       ret = mtk_i2c_set_speed(i2c, clk_get_rate(clk), clk_src_div);
+       ret = mtk_i2c_set_speed(i2c, clk_get_rate(clk));
        if (ret) {
                dev_err(&pdev->dev, "Failed to set the speed.\n");
                return -EINVAL;