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Subject[PATCH 4.19 22/49] i2c: meson: fix clock setting overwrite
Date
From: Jerome Brunet <jbrunet@baylibre.com>

commit 28683e847e2f20eed22cdd24f185d7783db396d3 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
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>
@@ -40,6 +41,12 @@
#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 {
@@ -149,6 +156,9 @@ 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);
}
@@ -276,7 +286,10 @@ 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);
}
@@ -435,6 +448,10 @@ 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;

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