linux-kernel - Re: [PATCH 2/7] iio: adc: stm32: Enable use of stm32 timer triggers

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Message-ID: <9826347e-d8e4-2386-cc7a-dd2c4909494b@kernel.org>
Date:   Sun, 22 Jan 2017 12:55:38 +0000
From:   Jonathan Cameron <jic23@...nel.org>
To:     Fabrice Gasnier <fabrice.gasnier@...com>, linux@...linux.org.uk,
        robh+dt@...nel.org, linux-arm-kernel@...ts.infradead.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     linux-iio@...r.kernel.org, mark.rutland@....com,
        mcoquelin.stm32@...il.com, alexandre.torgue@...com,
        lars@...afoo.de, knaack.h@....de, pmeerw@...erw.net,
        benjamin.gaignard@...aro.org, benjamin.gaignard@...com
Subject: Re: [PATCH 2/7] iio: adc: stm32: Enable use of stm32 timer triggers

On 19/01/17 13:34, Fabrice Gasnier wrote:
> STM32 ADC has external timer trigger sources. Use stm32 timer triggers
> API (e.g. is_stm32_timer_trigger()) with local ADC lookup table to
> validate a trigger can be used.
> This also provides correct trigger selection value (e.g. extsel).
> 
> Signed-off-by: Fabrice Gasnier <fabrice.gasnier@...com>
Looks good. Observations inline.
> ---
>  drivers/iio/adc/Kconfig     |  2 ++
>  drivers/iio/adc/stm32-adc.c | 60 +++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 62 insertions(+)
> 
> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> index 33341f4..9a7b090 100644
> --- a/drivers/iio/adc/Kconfig
> +++ b/drivers/iio/adc/Kconfig
> @@ -447,6 +447,8 @@ config STM32_ADC_CORE
>  	depends on OF
>  	depends on REGULATOR
>  	select IIO_BUFFER
> +	select MFD_STM32_TIMERS
> +	select IIO_STM32_TIMER_TRIGGER
>  	select IIO_TRIGGERED_BUFFER
>  	help
>  	  Select this option to enable the core driver for STMicroelectronics
> diff --git a/drivers/iio/adc/stm32-adc.c b/drivers/iio/adc/stm32-adc.c
> index 8d0b74b..30708bc 100644
> --- a/drivers/iio/adc/stm32-adc.c
> +++ b/drivers/iio/adc/stm32-adc.c
> @@ -23,6 +23,7 @@
>  #include <linux/delay.h>
>  #include <linux/iio/iio.h>
>  #include <linux/iio/buffer.h>
> +#include <linux/iio/timer/stm32-timer-trigger.h>
>  #include <linux/iio/trigger.h>
>  #include <linux/iio/trigger_consumer.h>
>  #include <linux/iio/triggered_buffer.h>
> @@ -122,6 +123,35 @@ enum stm32_adc_exten {
>  	STM32_EXTEN_HWTRIG_BOTH_EDGES,
>  };
>  
> +/* extsel - trigger mux selection value */
> +enum stm32_adc_extsel {
> +	STM32_EXT0,
> +	STM32_EXT1,
> +	STM32_EXT2,
> +	STM32_EXT3,
> +	STM32_EXT4,
> +	STM32_EXT5,
> +	STM32_EXT6,
> +	STM32_EXT7,
> +	STM32_EXT8,
> +	STM32_EXT9,
> +	STM32_EXT10,
> +	STM32_EXT11,
> +	STM32_EXT12,
> +	STM32_EXT13,
> +	STM32_EXT14,
> +	STM32_EXT15,
> +};
> +
> +/**
> + * struct stm32_adc_trig_info - ADC trigger info
> + * @name:		name of the trigger, corresponding to its source
> + * @extsel:		trigger selection
> + */
> +struct stm32_adc_trig_info {
> +	const char *name;
> +	enum stm32_adc_extsel extsel;
> +};
>  
>  /**
>   * struct stm32_adc - private data of each ADC IIO instance
> @@ -218,6 +248,26 @@ struct stm32_adc_regs {
>  	{ STM32F4_ADC_SQR1, STM32F4_SQ16_MASK, STM32F4_SQ16_SHIFT },
>  };
>  
> +/* STM32F4 external trigger sources for all instances */
> +static struct stm32_adc_trig_info stm32f4_adc_timer_trigs[] = {
> +	{ TIM1_CH1, STM32_EXT0 },
> +	{ TIM1_CH2, STM32_EXT1 },
> +	{ TIM1_CH3, STM32_EXT2 },
> +	{ TIM2_CH2, STM32_EXT3 },
> +	{ TIM2_CH3, STM32_EXT4 },
> +	{ TIM2_CH4, STM32_EXT5 },
> +	{ TIM2_TRGO, STM32_EXT6 },
> +	{ TIM3_CH1, STM32_EXT7 },
> +	{ TIM3_TRGO, STM32_EXT8 },
> +	{ TIM4_CH4, STM32_EXT9 },
> +	{ TIM5_CH1, STM32_EXT10 },
> +	{ TIM5_CH2, STM32_EXT11 },
> +	{ TIM5_CH3, STM32_EXT12 },
> +	{ TIM8_CH1, STM32_EXT13 },
> +	{ TIM8_TRGO, STM32_EXT14 },
> +	{}, /* sentinel */
> +};
> +
>  /**
>   * STM32 ADC registers access routines
>   * @adc: stm32 adc instance
> @@ -362,6 +412,16 @@ static int stm32_adc_conf_scan_seq(struct iio_dev *indio_dev,
>  static int stm32_adc_get_trig_extsel(struct iio_dev *indio_dev,
>  				     struct iio_trigger *trig)
>  {
> +	int i;
Ah. This makes more sense than patch 1 on it's own did.
> +
> +	/* lookup triggers registered by stm32 timer trigger driver */
> +	for (i = 0; stm32f4_adc_timer_trigs[i].name; i++) {
> +		if (is_stm32_timer_trigger(trig) &&
> +		    !strcmp(stm32f4_adc_timer_trigs[i].name, trig->name)) {
> +			return stm32f4_adc_timer_trigs[i].extsel;
Good. The combination of the first check and the name match should make this safe
against those triggers that can be assigned arbitrary names.
> +		}
> +	}
> +
>  	return -EINVAL;
>  }
>  
>