The clock divider has 12 bits, splitted into a 10 bit field and a
2 bit field. The extra 2 bits aren't used currently.
Change this to use the full 12 bits and warn if the requested
frequency is too low.
Signed-off-by: Heiner Kallweit <hkallweit1@xxxxxxxxx>
Acked-by: Jerome Brunet <jbrunet@xxxxxxxxxxxx>
---
v2:
- added Acked-by
v3:
- changed order of patches
v4:
- no changes
v5:
- change WARN_ON to dev_err
---
drivers/i2c/busses/i2c-meson.c | 16 ++++++++++++++--
1 file changed, 14 insertions(+), 2 deletions(-)
diff --git a/drivers/i2c/busses/i2c-meson.c b/drivers/i2c/busses/i2c-meson.c
index ac0ac82d..25ea05fc 100644
--- a/drivers/i2c/busses/i2c-meson.c
+++ b/drivers/i2c/busses/i2c-meson.c
@@ -35,7 +35,9 @@
#define REG_CTRL_STATUS BIT(2)
#define REG_CTRL_ERROR BIT(3)
#define REG_CTRL_CLKDIV_SHIFT 12
-#define REG_CTRL_CLKDIV_MASK ((BIT(10) - 1) << REG_CTRL_CLKDIV_SHIFT)
+#define REG_CTRL_CLKDIV_MASK GENMASK(21, 12)
+#define REG_CTRL_CLKDIVEXT_SHIFT 28
+#define REG_CTRL_CLKDIVEXT_MASK GENMASK(29, 28)
#define I2C_TIMEOUT_MS 500
@@ -134,8 +136,18 @@ static void meson_i2c_set_clk_div(struct meson_i2c *i2c, unsigned int freq)
unsigned int div;
div = DIV_ROUND_UP(clk_rate, freq * 4);
+
+ /* clock divider has 12 bits */
+ if (div >= (1 << 12)) {
+ dev_err(i2c->dev, "requested bus frequency too low\n");
+ div = (1 << 12) - 1;
+ }
+
meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_CLKDIV_MASK,
- div << REG_CTRL_CLKDIV_SHIFT);
+ (div & GENMASK(9, 0)) << REG_CTRL_CLKDIV_SHIFT);
+
+ meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_CLKDIVEXT_MASK,
+ (div >> 10) << REG_CTRL_CLKDIVEXT_SHIFT);
dev_dbg(i2c->dev, "%s: clk %lu, freq %u, div %u\n", __func__,
clk_rate, freq, div);
--
2.12.0
--
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