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From:   <kewei.xu@mediatek.com>
To:     <wsa@the-dreams.de>
CC:     <matthias.bgg@gmail.com>, <linux-i2c@vger.kernel.org>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-kernel@vger.kernel.org>,
        <linux-mediatek@lists.infradead.org>,
        <srv_heupstream@mediatek.com>, <leilk.liu@mediatek.com>,
        <qii.wang@mediatek.com>, Kewei Xu <kewei.xu@mediatek.com>
Subject: [PATCH] i2c: mediatek: Isolate speed setting via dts for special devices
Date:   Sat, 19 Jun 2021 17:23:17 +0800
Message-ID: <1624094597-23993-1-git-send-email-kewei.xu@mediatek.com>
MIME-Version: 1.0
Content-Type: text/plain
Precedence: bulk

From: Kewei Xu <kewei.xu@mediatek.com>

In the commit be5ce0e97cc7 ("i2c: mediatek: Add i2c ac-timing adjust
support"), the I2C timing calculation has been revised to support
ac-timing, 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.

Signed-off-by: Kewei Xu <kewei.xu@mediatek.com>
---
 drivers/i2c/busses/i2c-mt65xx.c | 86 ++++++++++++++++++++++++++++++++++++++---
 1 file changed, 81 insertions(+), 5 deletions(-)

diff --git a/drivers/i2c/busses/i2c-mt65xx.c b/drivers/i2c/busses/i2c-mt65xx.c
index ded94f9..486076f 100644
--- a/drivers/i2c/busses/i2c-mt65xx.c
+++ b/drivers/i2c/busses/i2c-mt65xx.c
@@ -41,6 +41,8 @@
 #define I2C_HANDSHAKE_RST		0x0020
 #define I2C_FIFO_ADDR_CLR		0x0001
 #define I2C_DELAY_LEN			0x0002
+#define I2C_ST_START_CON		0x8001
+#define I2C_FS_START_CON		0x1800
 #define I2C_TIME_CLR_VALUE		0x0000
 #define I2C_TIME_DEFAULT_VALUE		0x0003
 #define I2C_WRRD_TRANAC_VALUE		0x0002
@@ -63,6 +65,7 @@
 #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
@@ -247,6 +250,7 @@ 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 default_timing_adjust;	/* no timing adjust mode */
 
 	u16 irq_stat;			/* interrupt status */
 	unsigned int clk_src_div;
@@ -484,6 +488,7 @@ static void mtk_i2c_clock_disable(struct mtk_i2c *i2c)
 static void mtk_i2c_init_hw(struct mtk_i2c *i2c)
 {
 	u16 control_reg;
+	u16 ext_conf_val;
 
 	if (i2c->dev_comp->apdma_sync) {
 		writel(I2C_DMA_WARM_RST, i2c->pdmabase + OFFSET_RST);
@@ -518,8 +523,17 @@ static void mtk_i2c_init_hw(struct mtk_i2c *i2c)
 	if (i2c->dev_comp->ltiming_adjust)
 		mtk_i2c_writew(i2c, i2c->ltiming_reg, OFFSET_LTIMING);
 
-	if (i2c->dev_comp->timing_adjust) {
-		mtk_i2c_writew(i2c, i2c->ac_timing.ext, OFFSET_EXT_CONF);
+	if (i2c->speed_hz <= I2C_MAX_STANDARD_MODE_FREQ)
+		ext_conf_val = I2C_ST_START_CON;
+	else
+		ext_conf_val = I2C_FS_START_CON;
+
+	if (i2c->default_timing_adjust) {
+		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);
 		mtk_i2c_writew(i2c, I2C_SCL_MIS_COMP_VALUE,
@@ -544,6 +558,7 @@ static void mtk_i2c_init_hw(struct mtk_i2c *i2c)
 				       OFFSET_HS_STA_STO_AC_TIMING);
 		}
 	}
+	mtk_i2c_writew(i2c, ext_conf_val, OFFSET_EXT_CONF);
 
 	/* If use i2c pin from PMIC mt6397 side, need set PATH_DIR first */
 	if (i2c->have_pmic)
@@ -600,7 +615,7 @@ 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->default_timing_adjust || !i2c->dev_comp->timing_adjust)
 		return 0;
 
 	if (i2c->dev_comp->ltiming_adjust)
@@ -760,7 +775,63 @@ 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;
@@ -1284,6 +1355,8 @@ 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->default_timing_adjust =
+		of_property_read_bool(np, "mediatek,default-timing-adjust");
 
 	i2c_parse_fw_timings(i2c->dev, &i2c->timing_info, true);
 
@@ -1363,7 +1436,10 @@ 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->default_timing_adjust)
+		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