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Subject: Re: [PATCH 3/5] i2c: stm32f7: add support for DNF i2c-digital-filter
 binding
To:     Alain Volmat <alain.volmat@foss.st.com>, <wsa@kernel.org>,
        <robh+dt@kernel.org>
CC:     <mark.rutland@arm.com>, <mcoquelin.stm32@gmail.com>,
        <alexandre.torgue@foss.st.com>, <linux-i2c@vger.kernel.org>,
        <devicetree@vger.kernel.org>,
        <linux-stm32@st-md-mailman.stormreply.com>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-kernel@vger.kernel.org>, <fabrice.gasnier@foss.st.com>
References: <1612515104-838-1-git-send-email-alain.volmat@foss.st.com>
 <1612515104-838-4-git-send-email-alain.volmat@foss.st.com>
From:   Pierre Yves MORDRET <pierre-yves.mordret@foss.st.com>
Message-ID: <be1c42b6-c86b-7f17-bf50-f2f67ddb88af@foss.st.com>
Date:   Fri, 5 Feb 2021 15:59:19 +0100
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Hello all

Looks good to me

Signed-off-by: Pierre-Yves MORDRET <pierre-yves.mordret@foss.st.com>

Regards

On 2/5/21 9:51 AM, Alain Volmat wrote:
> 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);
> 

-- 
--
~ Py MORDRET
--