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Subject[PATCH 3/5] i2c: stm32f7: add support for DNF i2c-digital-filter binding
Date
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: Alain Volmat <alain.volmat@foss.st.com>
---
drivers/i2c/busses/i2c-stm32f7.c | 27 ++++++++++++++++-----------
1 file changed, 16 insertions(+), 11 deletions(-)

diff --git a/drivers/i2c/busses/i2c-stm32f7.c b/drivers/i2c/busses/i2c-stm32f7.c
index 0c539fea2754..f77cd6512a86 100644
--- a/drivers/i2c/busses/i2c-stm32f7.c
+++ b/drivers/i2c/busses/i2c-stm32f7.c
@@ -222,7 +222,6 @@ struct stm32f7_i2c_spec {
* @clock_src: I2C clock source frequency (Hz)
* @rise_time: Rise time (ns)
* @fall_time: Fall time (ns)
- * @dnf: Digital filter coefficient (0-16)
* @fmp_clr_offset: Fast Mode Plus clear register offset from set register
*/
struct stm32f7_i2c_setup {
@@ -230,7 +229,6 @@ struct stm32f7_i2c_setup {
u32 clock_src;
u32 rise_time;
u32 fall_time;
- u8 dnf;
u32 fmp_clr_offset;
};

@@ -310,6 +308,8 @@ struct stm32f7_i2c_msg {
* @smbus_mode: states that the controller is configured in SMBus mode
* @host_notify_client: SMBus host-notify client
* @analog_filter: boolean to indicate enabling of the analog filter
+ * @dnf_dt: value of digital filter requested via dt
+ * @dnf: value of digital filter to apply
*/
struct stm32f7_i2c_dev {
struct i2c_adapter adap;
@@ -339,6 +339,8 @@ struct stm32f7_i2c_dev {
bool smbus_mode;
struct i2c_client *host_notify_client;
bool analog_filter;
+ u32 dnf_dt;
+ u32 dnf;
};

/*
@@ -384,13 +386,11 @@ static struct stm32f7_i2c_spec stm32f7_i2c_specs[] = {
static const struct stm32f7_i2c_setup stm32f7_setup = {
.rise_time = STM32F7_I2C_RISE_TIME_DEFAULT,
.fall_time = STM32F7_I2C_FALL_TIME_DEFAULT,
- .dnf = STM32F7_I2C_DNF_DEFAULT,
};

static const struct stm32f7_i2c_setup stm32mp15_setup = {
.rise_time = STM32F7_I2C_RISE_TIME_DEFAULT,
.fall_time = STM32F7_I2C_FALL_TIME_DEFAULT,
- .dnf = STM32F7_I2C_DNF_DEFAULT,
.fmp_clr_offset = 0x40,
};

@@ -459,10 +459,11 @@ static int stm32f7_i2c_compute_timing(struct stm32f7_i2c_dev *i2c_dev,
return -EINVAL;
}

- if (setup->dnf > STM32F7_I2C_DNF_MAX) {
+ i2c_dev->dnf = DIV_ROUND_CLOSEST(i2c_dev->dnf_dt, i2cclk);
+ if (i2c_dev->dnf > STM32F7_I2C_DNF_MAX) {
dev_err(i2c_dev->dev,
"DNF out of bound %d/%d\n",
- setup->dnf, STM32F7_I2C_DNF_MAX);
+ i2c_dev->dnf * i2cclk, STM32F7_I2C_DNF_MAX * i2cclk);
return -EINVAL;
}

@@ -473,13 +474,13 @@ static int stm32f7_i2c_compute_timing(struct stm32f7_i2c_dev *i2c_dev,
af_delay_max =
(i2c_dev->analog_filter ?
STM32F7_I2C_ANALOG_FILTER_DELAY_MAX : 0);
- dnf_delay = setup->dnf * i2cclk;
+ dnf_delay = i2c_dev->dnf * i2cclk;

sdadel_min = specs->hddat_min + setup->fall_time -
- af_delay_min - (setup->dnf + 3) * i2cclk;
+ af_delay_min - (i2c_dev->dnf + 3) * i2cclk;

sdadel_max = specs->vddat_max - setup->rise_time -
- af_delay_max - (setup->dnf + 4) * i2cclk;
+ af_delay_max - (i2c_dev->dnf + 4) * i2cclk;

scldel_min = setup->rise_time + specs->sudat_min;

@@ -645,6 +646,7 @@ static int stm32f7_i2c_setup_timing(struct stm32f7_i2c_dev *i2c_dev,
setup->speed_freq = t->bus_freq_hz;
i2c_dev->setup.rise_time = t->scl_rise_ns;
i2c_dev->setup.fall_time = t->scl_fall_ns;
+ i2c_dev->dnf_dt = t->digital_filter_width_ns;
setup->clock_src = clk_get_rate(i2c_dev->clk);

if (!setup->clock_src) {
@@ -652,6 +654,9 @@ static int stm32f7_i2c_setup_timing(struct stm32f7_i2c_dev *i2c_dev,
return -EINVAL;
}

+ if (!of_property_read_bool(i2c_dev->dev->of_node, "i2c-digital-filter"))
+ i2c_dev->dnf_dt = STM32F7_I2C_DNF_DEFAULT;
+
do {
ret = stm32f7_i2c_compute_timing(i2c_dev, setup,
&i2c_dev->timing);
@@ -681,7 +686,7 @@ static int stm32f7_i2c_setup_timing(struct stm32f7_i2c_dev *i2c_dev,
dev_dbg(i2c_dev->dev, "I2C Rise(%i) and Fall(%i) Time\n",
setup->rise_time, setup->fall_time);
dev_dbg(i2c_dev->dev, "I2C Analog Filter(%s), DNF(%i)\n",
- (i2c_dev->analog_filter ? "On" : "Off"), setup->dnf);
+ (i2c_dev->analog_filter ? "On" : "Off"), i2c_dev->dnf);

i2c_dev->bus_rate = setup->speed_freq;

@@ -732,7 +737,7 @@ static void stm32f7_i2c_hw_config(struct stm32f7_i2c_dev *i2c_dev)
stm32f7_i2c_clr_bits(i2c_dev->base + STM32F7_I2C_CR1,
STM32F7_I2C_CR1_DNF_MASK);
stm32f7_i2c_set_bits(i2c_dev->base + STM32F7_I2C_CR1,
- STM32F7_I2C_CR1_DNF(i2c_dev->setup.dnf));
+ STM32F7_I2C_CR1_DNF(i2c_dev->dnf));

stm32f7_i2c_set_bits(i2c_dev->base + STM32F7_I2C_CR1,
STM32F7_I2C_CR1_PE);
--
2.17.1
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