[PATCH v6 6/7] i2c: mediatek: Isolate speed setting via dts for special devices

[Kewei Xu]

In the commit be5ce0e97cc7 ("i2c: mediatek: Add i2c ac-timing adjust
support"), the I2C timing calculation has been revised to support
ac-timing adjustment, however that will break on some I2C components.
As a result we want to introduce a new setting "default-adjust-timing"
so those components can choose to use the old (default) timing algorithm.

Fixes: be5ce0e97cc7 ("i2c: mediatek: Add i2c ac-timing adjust support")
Signed-off-by: Kewei Xu <kewei.xu@xxxxxxxxxxxx>
---
 drivers/i2c/busses/i2c-mt65xx.c | 77 ++++++++++++++++++++++++++++++++++++++---
 1 file changed, 73 insertions(+), 4 deletions(-)

diff --git a/drivers/i2c/busses/i2c-mt65xx.c b/drivers/i2c/busses/i2c-mt65xx.c
index 6ded82e..0cf130b 100644
--- a/drivers/i2c/busses/i2c-mt65xx.c
+++ b/drivers/i2c/busses/i2c-mt65xx.c
@@ -66,6 +66,7 @@
 #define I2C_DMA_HARD_RST		0x0002
 #define I2C_DMA_HANDSHAKE_RST		0x0004
 
+#define I2C_DEFAULT_CLK_DIV		5
 #define MAX_SAMPLE_CNT_DIV		8
 #define MAX_STEP_CNT_DIV		64
 #define MAX_CLOCK_DIV			256
@@ -250,6 +251,7 @@ struct mtk_i2c {
 	struct clk *clk_arb;		/* Arbitrator clock for i2c */
 	bool have_pmic;			/* can use i2c pins from PMIC */
 	bool use_push_pull;		/* IO config push-pull mode */
+	bool use_default_timing;	/* no timing adjust mode */
 
 	u16 irq_stat;			/* interrupt status */
 	unsigned int clk_src_div;
@@ -532,7 +534,11 @@ static void mtk_i2c_init_hw(struct mtk_i2c *i2c)
 	else
 		ext_conf_val = I2C_FS_START_CON;
 
-	if (i2c->dev_comp->timing_adjust) {
+	if (i2c->use_default_timing) {
+		if (i2c->dev_comp->timing_adjust)
+			mtk_i2c_writew(i2c, I2C_DEFAULT_CLK_DIV - 1,
+				       OFFSET_CLOCK_DIV);
+	} else if (i2c->dev_comp->timing_adjust) {
 		ext_conf_val = i2c->ac_timing.ext;
 		mtk_i2c_writew(i2c, i2c->ac_timing.inter_clk_div,
 			       OFFSET_CLOCK_DIV);
@@ -615,7 +621,7 @@ static int mtk_i2c_check_ac_timing(struct mtk_i2c *i2c,
 	unsigned int sample_ns = div_u64(1000000000ULL * (sample_cnt + 1),
 					 clk_src);
 
-	if (!i2c->dev_comp->timing_adjust)
+	if (i2c->use_default_timing || !i2c->dev_comp->timing_adjust)
 		return 0;
 
 	if (i2c->dev_comp->ltiming_adjust)
@@ -775,7 +781,65 @@ static int mtk_i2c_calculate_speed(struct mtk_i2c *i2c, unsigned int clk_src,
 	return 0;
 }
 
-static int mtk_i2c_set_speed(struct mtk_i2c *i2c, unsigned int parent_clk)
+static int mtk_i2c_set_speed_default_timing(struct mtk_i2c *i2c,
+					    unsigned int parent_clk)
+{
+	unsigned int clk_src;
+	unsigned int step_cnt;
+	unsigned int sample_cnt;
+	unsigned int l_step_cnt;
+	unsigned int l_sample_cnt;
+	unsigned int target_speed;
+	int ret;
+
+	if (i2c->dev_comp->timing_adjust)
+		i2c->clk_src_div *= I2C_DEFAULT_CLK_DIV;
+
+	clk_src = parent_clk / i2c->clk_src_div;
+	target_speed = i2c->speed_hz;
+
+	if (target_speed > I2C_MAX_FAST_MODE_PLUS_FREQ) {
+		/* Set master code speed register */
+		ret = mtk_i2c_calculate_speed(i2c, clk_src,
+					      I2C_MAX_FAST_MODE_FREQ,
+					      &l_step_cnt, &l_sample_cnt);
+		if (ret < 0)
+			return ret;
+
+		i2c->timing_reg = (l_sample_cnt << 8) | l_step_cnt;
+
+		/* Set the high speed mode register */
+		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);
+
+		if (i2c->dev_comp->ltiming_adjust)
+			i2c->ltiming_reg = (l_sample_cnt << 6) | l_step_cnt |
+					   (sample_cnt << 12) | (step_cnt << 9);
+	} else {
+		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;
+
+		if (i2c->dev_comp->ltiming_adjust)
+			i2c->ltiming_reg = (sample_cnt << 6) | step_cnt;
+	}
+
+	return 0;
+}
+
+static int mtk_i2c_set_speed_adjust_timing(struct mtk_i2c *i2c,
+					   unsigned int parent_clk)
 {
 	unsigned int clk_src;
 	unsigned int step_cnt;
@@ -1271,6 +1335,8 @@ static int mtk_i2c_parse_dt(struct device_node *np, struct mtk_i2c *i2c)
 	i2c->have_pmic = of_property_read_bool(np, "mediatek,have-pmic");
 	i2c->use_push_pull =
 		of_property_read_bool(np, "mediatek,use-push-pull");
+	i2c->use_default_timing =
+		of_property_read_bool(np, "mediatek,use-default-timing");
 
 	i2c_parse_fw_timings(i2c->dev, &i2c->timing_info, true);
 
@@ -1357,7 +1423,10 @@ 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));
+	if (i2c->use_default_timing)
+		ret = mtk_i2c_set_speed_default_timing(i2c, clk_get_rate(clk));
+	else
+		ret = mtk_i2c_set_speed_adjust_timing(i2c, clk_get_rate(clk));
 	if (ret) {
 		dev_err(&pdev->dev, "Failed to set the speed.\n");
 		return -EINVAL;
-- 
1.9.1