i2c: stm32f7: add support for DNF i2c-digital-filter binding

Add the support for the i2c-digital-filter binding, allowing to enable
the digital filter via the device-tree and indicate its value in the DT

Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
Signed-off-by: Patrice Chotard <patrice.chotard@foss.st.com>
Reviewed-by: Patrice Chotard <patrice.chotard@foss.st.com>

diff --git a/drivers/i2c/stm32f7_i2c.c b/drivers/i2c/stm32f7_i2c.c
index 7e6c65f..2b2dae6 100644 (file)
--- a/drivers/i2c/stm32f7_i2c.c
+++ b/drivers/i2c/stm32f7_i2c.c
@@ -107,7 +107,6 @@ struct stm32_i2c_regs {
 
 #define STM32_I2C_MAX_LEN                      0xff
 
-#define STM32_I2C_DNF_DEFAULT                  0
 #define STM32_I2C_DNF_MAX                      15
 
 #define STM32_I2C_ANALOG_FILTER_DELAY_MIN      50      /* ns */
@@ -204,6 +203,7 @@ struct stm32_i2c_timings {
  * @regmap_sreg: register address for setting Fast Mode Plus bits
  * @regmap_creg: register address for clearing Fast Mode Plus bits
  * @regmap_mask: mask for Fast Mode Plus bits
+ * @dnf_dt: value of digital filter requested via dt
  */
 struct stm32_i2c_priv {
        struct stm32_i2c_regs *regs;
@@ -214,6 +214,7 @@ struct stm32_i2c_priv {
        u32 regmap_sreg;
        u32 regmap_creg;
        u32 regmap_mask;
+       u32 dnf_dt;
 };
 
 static const struct stm32_i2c_spec i2c_specs[] = {
@@ -684,6 +685,7 @@ static int stm32_i2c_compute_timing(struct stm32_i2c_priv *i2c_priv,
        const struct stm32_i2c_spec *specs;
        struct stm32_i2c_timings *v, *_v;
        struct list_head solutions;
+       u32 i2cclk = DIV_ROUND_CLOSEST(STM32_NSEC_PER_SEC, setup->clock_src);
        int ret;
 
        specs = get_specs(setup->speed_freq);
@@ -701,6 +703,8 @@ static int stm32_i2c_compute_timing(struct stm32_i2c_priv *i2c_priv,
                return -EINVAL;
        }
 
+       /*  Analog and Digital Filters */
+       setup->dnf = DIV_ROUND_CLOSEST(i2c_priv->dnf_dt, i2cclk);
        if (setup->dnf > STM32_I2C_DNF_MAX) {
                log_err("DNF out of bound %d/%d\n",
                        setup->dnf, STM32_I2C_DNF_MAX);
@@ -923,7 +927,10 @@ static int stm32_of_to_plat(struct udevice *dev)
        fall_time = dev_read_u32_default(dev, "i2c-scl-falling-time-ns",
                                         STM32_I2C_FALL_TIME_DEFAULT);
 
-       i2c_priv->setup.dnf = STM32_I2C_DNF_DEFAULT;
+       i2c_priv->dnf_dt = dev_read_u32_default(dev, "i2c-digital-filter-width-ns", 0);
+       if (!dev_read_bool(dev, "i2c-digital-filter"))
+               i2c_priv->dnf_dt = 0;
+
        i2c_priv->setup.analog_filter = dev_read_bool(dev, "i2c-analog-filter");
 
        /* Optional */