On Wed, 2017-03-08 at 07:44 +0100, Heiner Kallweit wrote: > 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> > --- > drivers/i2c/busses/i2c-meson.c | 13 +++++++++++-- > 1 file changed, 11 insertions(+), 2 deletions(-) > > diff --git a/drivers/i2c/busses/i2c-meson.c b/drivers/i2c/busses/i2c-meson.c > index 5e243efa..a5764be5 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 > > @@ -136,8 +138,15 @@ static void meson_i2c_set_clk_div(struct meson_i2c *i2c) > unsigned int div; > > div = DIV_ROUND_UP(clk_rate, i2c->timings.bus_freq_hz * 4); > + > + /* clock divider has 12 bits */ > + WARN_ON(div >= (1 << 12)); > + > 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, i2c->timings.bus_freq_hz, div); Acked-by: Jerome Brunet <jbrunet@xxxxxxxxxxxx> -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
