From f606aab3f1a49d723d66e14e545f6ca45005bda6 Mon Sep 17 00:00:00 2001 From: Kewei Xu Date: Thu, 17 Feb 2022 20:22:43 +0800 Subject: [PATCH 04/16] i2c: mediatek: modify bus speed calculation formula When clock-div is 0 or greater than 1, the bus speed calculated by the old speed calculation formula will be larger than the target speed. So we update the formula. Signed-off-by: Kewei Xu Reviewed-by: AngeloGioacchino Del Regno Reviewed-by: Qii Wang Signed-off-by: Wolfram Sang --- drivers/i2c/busses/i2c-mt65xx.c | 51 ++++++++++++++++++++++++++------- 1 file changed, 41 insertions(+), 10 deletions(-) --- a/drivers/i2c/busses/i2c-mt65xx.c +++ b/drivers/i2c/busses/i2c-mt65xx.c @@ -67,11 +67,12 @@ #define MAX_SAMPLE_CNT_DIV 8 #define MAX_STEP_CNT_DIV 64 -#define MAX_CLOCK_DIV 256 +#define MAX_CLOCK_DIV_8BITS 256 +#define MAX_CLOCK_DIV_5BITS 32 #define MAX_HS_STEP_CNT_DIV 8 -#define I2C_STANDARD_MODE_BUFFER (1000 / 2) -#define I2C_FAST_MODE_BUFFER (300 / 2) -#define I2C_FAST_MODE_PLUS_BUFFER (20 / 2) +#define I2C_STANDARD_MODE_BUFFER (1000 / 3) +#define I2C_FAST_MODE_BUFFER (300 / 3) +#define I2C_FAST_MODE_PLUS_BUFFER (20 / 3) #define I2C_CONTROL_RS (0x1 << 1) #define I2C_CONTROL_DMA_EN (0x1 << 2) @@ -604,6 +605,31 @@ static int mtk_i2c_max_step_cnt(unsigned return MAX_STEP_CNT_DIV; } +static int mtk_i2c_get_clk_div_restri(struct mtk_i2c *i2c, + unsigned int sample_cnt) +{ + int clk_div_restri = 0; + + if (i2c->dev_comp->ltiming_adjust == 0) + return 0; + + if (sample_cnt == 1) { + if (i2c->ac_timing.inter_clk_div == 0) + clk_div_restri = 0; + else + clk_div_restri = 1; + } else { + if (i2c->ac_timing.inter_clk_div == 0) + clk_div_restri = -1; + else if (i2c->ac_timing.inter_clk_div == 1) + clk_div_restri = 0; + else + clk_div_restri = 1; + } + + return clk_div_restri; +} + /* * Check and Calculate i2c ac-timing * @@ -732,6 +758,7 @@ static int mtk_i2c_calculate_speed(struc unsigned int best_mul; unsigned int cnt_mul; int ret = -EINVAL; + int clk_div_restri = 0; if (target_speed > I2C_MAX_HIGH_SPEED_MODE_FREQ) target_speed = I2C_MAX_HIGH_SPEED_MODE_FREQ; @@ -749,7 +776,8 @@ static int mtk_i2c_calculate_speed(struc * optimizing for sample_cnt * step_cnt being minimal */ for (sample_cnt = 1; sample_cnt <= MAX_SAMPLE_CNT_DIV; sample_cnt++) { - step_cnt = DIV_ROUND_UP(opt_div, sample_cnt); + clk_div_restri = mtk_i2c_get_clk_div_restri(i2c, sample_cnt); + step_cnt = DIV_ROUND_UP(opt_div + clk_div_restri, sample_cnt); cnt_mul = step_cnt * sample_cnt; if (step_cnt > max_step_cnt) continue; @@ -763,7 +791,7 @@ static int mtk_i2c_calculate_speed(struc best_mul = cnt_mul; base_sample_cnt = sample_cnt; base_step_cnt = step_cnt; - if (best_mul == opt_div) + if (best_mul == (opt_div + clk_div_restri)) break; } } @@ -774,7 +802,8 @@ static int mtk_i2c_calculate_speed(struc sample_cnt = base_sample_cnt; step_cnt = base_step_cnt; - if ((clk_src / (2 * sample_cnt * step_cnt)) > target_speed) { + if ((clk_src / (2 * (sample_cnt * step_cnt - clk_div_restri))) > + target_speed) { /* In this case, hardware can't support such * low i2c_bus_freq */ @@ -803,13 +832,16 @@ static int mtk_i2c_set_speed(struct mtk_ target_speed = i2c->speed_hz; parent_clk /= i2c->clk_src_div; - if (i2c->dev_comp->timing_adjust) - max_clk_div = MAX_CLOCK_DIV; + if (i2c->dev_comp->timing_adjust && i2c->dev_comp->ltiming_adjust) + max_clk_div = MAX_CLOCK_DIV_5BITS; + else if (i2c->dev_comp->timing_adjust) + max_clk_div = MAX_CLOCK_DIV_8BITS; else max_clk_div = 1; for (clk_div = 1; clk_div <= max_clk_div; clk_div++) { clk_src = parent_clk / clk_div; + i2c->ac_timing.inter_clk_div = clk_div - 1; if (target_speed > I2C_MAX_FAST_MODE_PLUS_FREQ) { /* Set master code speed register */ @@ -856,7 +888,6 @@ static int mtk_i2c_set_speed(struct mtk_ break; } - i2c->ac_timing.inter_clk_div = clk_div - 1; return 0; }