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