Commit b5a796c6 authored by Kewei Xu's avatar Kewei Xu Committed by Wolfram Sang
Browse files

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: default avatarKewei Xu <kewei.xu@mediatek.com>
Reviewed-by: default avatarAngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: default avatarQii Wang <qii.wang@mediatek.com>
Signed-off-by: default avatarWolfram Sang <wsa@kernel.org>
parent 17ba1e87

drivers/i2c/busses/i2c-mt65xx.c

+41 −10
Original line number Diff line number Diff line
@@ -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 int target_speed) 
		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(struct mtk_i2c *i2c, unsigned int clk_src, 
	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(struct mtk_i2c *i2c, unsigned int clk_src, 
	 * 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(struct mtk_i2c *i2c, unsigned int clk_src, 
			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(struct mtk_i2c *i2c, unsigned int clk_src, 
	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_i2c *i2c, unsigned int parent_clk) 
	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_i2c *i2c, unsigned int parent_clk) 
		break;

	}



	i2c->ac_timing.inter_clk_div = clk_div - 1;



	return 0;

}