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i2c: meson: use full 12 bits for clock divider 

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@gmail.com>
Acked-by: Jerome Brunet <jbrunet@baylibre.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
This commit is contained in:
Heiner Kallweit 2017-03-25 14:07:57 +01:00 committed by Wolfram Sang
parent 39b2ca6853
commit 47bb8f71ca
1 changed files with 14 additions and 2 deletions
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16
drivers/i2c/busses/i2c-meson.c
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@ -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);