diff options
Diffstat (limited to 'drivers/i2c/busses/i2c-meson.c')
-rw-r--r-- | drivers/i2c/busses/i2c-meson.c | 115 |
1 files changed, 85 insertions, 30 deletions
diff --git a/drivers/i2c/busses/i2c-meson.c b/drivers/i2c/busses/i2c-meson.c index 07eb819072c4..61cc5b2462c6 100644 --- a/drivers/i2c/busses/i2c-meson.c +++ b/drivers/i2c/busses/i2c-meson.c @@ -30,18 +30,21 @@ #define REG_TOK_RDATA1 0x1c /* Control register fields */ -#define REG_CTRL_START BIT(0) -#define REG_CTRL_ACK_IGNORE BIT(1) -#define REG_CTRL_STATUS BIT(2) -#define REG_CTRL_ERROR BIT(3) -#define REG_CTRL_CLKDIV GENMASK(21, 12) -#define REG_CTRL_CLKDIVEXT 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 REG_CTRL_START BIT(0) +#define REG_CTRL_ACK_IGNORE BIT(1) +#define REG_CTRL_STATUS BIT(2) +#define REG_CTRL_ERROR BIT(3) +#define REG_CTRL_CLKDIV_SHIFT 12 +#define REG_CTRL_CLKDIV_MASK GENMASK(21, REG_CTRL_CLKDIV_SHIFT) +#define REG_CTRL_CLKDIVEXT_SHIFT 28 +#define REG_CTRL_CLKDIVEXT_MASK GENMASK(29, REG_CTRL_CLKDIVEXT_SHIFT) + +#define REG_SLV_ADDR_MASK GENMASK(7, 0) +#define REG_SLV_SDA_FILTER_MASK GENMASK(10, 8) +#define REG_SLV_SCL_FILTER_MASK GENMASK(13, 11) +#define REG_SLV_SCL_LOW_SHIFT 16 +#define REG_SLV_SCL_LOW_MASK GENMASK(27, REG_SLV_SCL_LOW_SHIFT) +#define REG_SLV_SCL_LOW_EN BIT(28) #define I2C_TIMEOUT_MS 500 #define FILTER_DELAY 15 @@ -62,10 +65,6 @@ enum { STATE_WRITE, }; -struct meson_i2c_data { - unsigned char div_factor; -}; - /** * struct meson_i2c - Meson I2C device private data * @@ -83,7 +82,7 @@ struct meson_i2c_data { * @done: Completion used to wait for transfer termination * @tokens: Sequence of tokens to be written to the device * @num_tokens: Number of tokens - * @data: Pointer to the controlller's platform data + * @data: Pointer to the controller's platform data */ struct meson_i2c { struct i2c_adapter adap; @@ -106,6 +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) { @@ -134,14 +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)) { @@ -149,11 +200,11 @@ static void meson_i2c_set_clk_div(struct meson_i2c *i2c, unsigned int freq) div = GENMASK(11, 0); } - meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_CLKDIV, - FIELD_PREP(REG_CTRL_CLKDIV, div & GENMASK(9, 0))); + meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_CLKDIV_MASK, + FIELD_PREP(REG_CTRL_CLKDIV_MASK, div & GENMASK(9, 0))); - meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_CLKDIVEXT, - FIELD_PREP(REG_CTRL_CLKDIVEXT, div >> 10)); + meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_CLKDIVEXT_MASK, + FIELD_PREP(REG_CTRL_CLKDIVEXT_MASK, div >> 10)); /* Disable HIGH/LOW mode */ meson_i2c_set_mask(i2c, REG_SLAVE_ADDR, REG_SLV_SCL_LOW_EN, 0); @@ -292,8 +343,8 @@ static void meson_i2c_do_start(struct meson_i2c *i2c, struct i2c_msg *msg) TOKEN_SLAVE_ADDR_WRITE; - meson_i2c_set_mask(i2c, REG_SLAVE_ADDR, REG_SLV_ADDR, - FIELD_PREP(REG_SLV_ADDR, msg->addr << 1)); + meson_i2c_set_mask(i2c, REG_SLAVE_ADDR, REG_SLV_ADDR_MASK, + FIELD_PREP(REG_SLV_ADDR_MASK, msg->addr << 1)); meson_i2c_add_token(i2c, TOKEN_START); meson_i2c_add_token(i2c, token); @@ -467,9 +518,13 @@ static int meson_i2c_probe(struct platform_device *pdev) /* Disable filtering */ meson_i2c_set_mask(i2c, REG_SLAVE_ADDR, - REG_SLV_SDA_FILTER | REG_SLV_SCL_FILTER, 0); + 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) { + clk_disable_unprepare(i2c->clk); + return -EINVAL; + } + i2c->data->set_clk_div(i2c, timings.bus_freq_hz); ret = i2c_add_adapter(&i2c->adap); if (ret < 0) { @@ -491,15 +546,15 @@ 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[] = { |