From 28683e847e2f20eed22cdd24f185d7783db396d3 Mon Sep 17 00:00:00 2001
From: Jerome Brunet <jbrunet@baylibre.com>
Date: Wed, 7 Oct 2020 10:07:49 +0200
Subject: [PATCH] i2c: meson: fix clock setting overwrite
Git-commit: 28683e847e2f20eed22cdd24f185d7783db396d3
Patch-mainline: v5.9
References: git-fixes

When the slave address is written in do_start(), SLAVE_ADDR is written
completely. This may overwrite some setting related to the clock rate
or signal filtering.

Fix this by writing only the bits related to slave address. To avoid
causing unexpected changed, explicitly disable filtering or high/low
clock mode which may have been left over by the bootloader.

Fixes: 30021e3707a7 ("i2c: add support for Amlogic Meson I2C controller")
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/i2c/busses/i2c-meson.c |   19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

--- a/drivers/i2c/busses/i2c-meson.c
+++ b/drivers/i2c/busses/i2c-meson.c
@@ -8,6 +8,7 @@
  * published by the Free Software Foundation.
  */
 
+#include <linux/bitfield.h>
 #include <linux/clk.h>
 #include <linux/completion.h>
 #include <linux/i2c.h>
@@ -39,6 +40,12 @@
 #define REG_CTRL_CLKDIVEXT_SHIFT 28
 #define REG_CTRL_CLKDIVEXT_MASK	GENMASK(29, 28)
 
+#define REG_SLV_ADDR		GENMASK(7, 0)
+#define REG_SLV_SDA_FILTER	GENMASK(10, 8)
+#define REG_SLV_SCL_FILTER	GENMASK(13, 11)
+#define REG_SLV_SCL_LOW		GENMASK(27, 16)
+#define REG_SLV_SCL_LOW_EN	BIT(28)
+
 #define I2C_TIMEOUT_MS		500
 
 enum {
@@ -142,6 +149,9 @@ static void meson_i2c_set_clk_div(struct
 	meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_CLKDIVEXT_MASK,
 			   (div >> 10) << REG_CTRL_CLKDIVEXT_SHIFT);
 
+	/* Disable HIGH/LOW mode */
+	meson_i2c_set_mask(i2c, REG_SLAVE_ADDR, REG_SLV_SCL_LOW_EN, 0);
+
 	dev_dbg(i2c->dev, "%s: clk %lu, freq %u, div %u\n", __func__,
 		clk_rate, freq, div);
 }
@@ -269,7 +279,10 @@ static void meson_i2c_do_start(struct me
 	token = (msg->flags & I2C_M_RD) ? TOKEN_SLAVE_ADDR_READ :
 		TOKEN_SLAVE_ADDR_WRITE;
 
-	writel(msg->addr << 1, i2c->regs + REG_SLAVE_ADDR);
+
+	meson_i2c_set_mask(i2c, REG_SLAVE_ADDR, REG_SLV_ADDR,
+			   FIELD_PREP(REG_SLV_ADDR, msg->addr << 1));
+
 	meson_i2c_add_token(i2c, TOKEN_START);
 	meson_i2c_add_token(i2c, token);
 }
@@ -425,6 +438,10 @@ static int meson_i2c_probe(struct platfo
 		return ret;
 	}
 
+	/* Disable filtering */
+	meson_i2c_set_mask(i2c, REG_SLAVE_ADDR,
+			   REG_SLV_SDA_FILTER | REG_SLV_SCL_FILTER, 0);
+
 	meson_i2c_set_clk_div(i2c, timings.bus_freq_hz);
 
 	return 0;