summaryrefslogtreecommitdiff
path: root/drivers/i2c/busses/i2c-meson.c
diff options
context:
space:
mode:
Diffstat (limited to 'drivers/i2c/busses/i2c-meson.c')
-rw-r--r--drivers/i2c/busses/i2c-meson.c115
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[] = {