diff options
Diffstat (limited to 'drivers/i2c')
| -rw-r--r-- | drivers/i2c/busses/i2c-meson.c | 70 |
1 files changed, 60 insertions, 10 deletions
diff --git a/drivers/i2c/busses/i2c-meson.c b/drivers/i2c/busses/i2c-meson.c index 4b4a5b2d77ab..50dab123380a 100644 --- a/drivers/i2c/busses/i2c-meson.c +++ b/drivers/i2c/busses/i2c-meson.c @@ -65,10 +65,6 @@ enum { STATE_WRITE, }; -struct meson_i2c_data { - unsigned char div_factor; -}; - /** * struct meson_i2c - Meson I2C device private data * @@ -109,6 +105,10 @@ struct meson_i2c { const struct meson_i2c_data *data; }; +struct meson_i2c_data { + void (*set_clk_div)(struct meson_i2c *i2c, unsigned int freq); +}; + static void meson_i2c_set_mask(struct meson_i2c *i2c, int reg, u32 mask, u32 val) { @@ -137,14 +137,62 @@ static void meson_i2c_add_token(struct meson_i2c *i2c, int token) i2c->num_tokens++; } -static void meson_i2c_set_clk_div(struct meson_i2c *i2c, unsigned int freq) +static void meson_gxbb_axg_i2c_set_clk_div(struct meson_i2c *i2c, unsigned int freq) +{ + unsigned long clk_rate = clk_get_rate(i2c->clk); + unsigned int div_h, div_l; + + /* According to I2C-BUS Spec 2.1, in FAST-MODE, the minimum LOW period is 1.3uS, and + * minimum HIGH is least 0.6us. + * For 400000 freq, the period is 2.5us. To keep within the specs, give 40% of period to + * HIGH and 60% to LOW. This means HIGH at 1.0us and LOW 1.5us. + * The same applies for Fast-mode plus, where LOW is 0.5us and HIGH is 0.26us. + * Duty = H/(H + L) = 2/5 + */ + if (freq <= I2C_MAX_STANDARD_MODE_FREQ) { + div_h = DIV_ROUND_UP(clk_rate, freq); + div_l = DIV_ROUND_UP(div_h, 4); + div_h = DIV_ROUND_UP(div_h, 2) - FILTER_DELAY; + } else { + div_h = DIV_ROUND_UP(clk_rate * 2, freq * 5) - FILTER_DELAY; + div_l = DIV_ROUND_UP(clk_rate * 3, freq * 5 * 2); + } + + /* clock divider has 12 bits */ + if (div_h > GENMASK(11, 0)) { + dev_err(i2c->dev, "requested bus frequency too low\n"); + div_h = GENMASK(11, 0); + } + if (div_l > GENMASK(11, 0)) { + dev_err(i2c->dev, "requested bus frequency too low\n"); + div_l = GENMASK(11, 0); + } + + meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_CLKDIV_MASK, + FIELD_PREP(REG_CTRL_CLKDIV_MASK, div_h & GENMASK(9, 0))); + + meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_CLKDIVEXT_MASK, + FIELD_PREP(REG_CTRL_CLKDIVEXT_MASK, div_h >> 10)); + + /* set SCL low delay */ + meson_i2c_set_mask(i2c, REG_SLAVE_ADDR, REG_SLV_SCL_LOW_MASK, + FIELD_PREP(REG_SLV_SCL_LOW_MASK, div_l)); + + /* Enable HIGH/LOW mode */ + meson_i2c_set_mask(i2c, REG_SLAVE_ADDR, REG_SLV_SCL_LOW_EN, REG_SLV_SCL_LOW_EN); + + dev_dbg(i2c->dev, "%s: clk %lu, freq %u, divh %u, divl %u\n", __func__, + clk_rate, freq, div_h, div_l); +} + +static void meson6_i2c_set_clk_div(struct meson_i2c *i2c, unsigned int freq) { unsigned long clk_rate = clk_get_rate(i2c->clk); unsigned int div; div = DIV_ROUND_UP(clk_rate, freq); div -= FILTER_DELAY; - div = DIV_ROUND_UP(div, i2c->data->div_factor); + div = DIV_ROUND_UP(div, 4); /* clock divider has 12 bits */ if (div > GENMASK(11, 0)) { @@ -472,7 +520,9 @@ static int meson_i2c_probe(struct platform_device *pdev) meson_i2c_set_mask(i2c, REG_SLAVE_ADDR, REG_SLV_SDA_FILTER_MASK | REG_SLV_SCL_FILTER_MASK, 0); - meson_i2c_set_clk_div(i2c, timings.bus_freq_hz); + if (!i2c->data->set_clk_div) + return -EINVAL; + i2c->data->set_clk_div(i2c, timings.bus_freq_hz); ret = i2c_add_adapter(&i2c->adap); if (ret < 0) { @@ -494,15 +544,15 @@ static int meson_i2c_remove(struct platform_device *pdev) } static const struct meson_i2c_data i2c_meson6_data = { - .div_factor = 4, + .set_clk_div = meson6_i2c_set_clk_div, }; static const struct meson_i2c_data i2c_gxbb_data = { - .div_factor = 4, + .set_clk_div = meson_gxbb_axg_i2c_set_clk_div, }; static const struct meson_i2c_data i2c_axg_data = { - .div_factor = 3, + .set_clk_div = meson_gxbb_axg_i2c_set_clk_div, }; static const struct of_device_id meson_i2c_match[] = { |