Re: [PATCH v2 6/8] iio: trigger: Add STM32 LPTimer trigger driver

[Jonathan Cameron <jic23-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>]

On Wed, 21 Jun 2017 16:30:13 +0200
Fabrice Gasnier <fabrice.gasnier-qxv4g6HH51o@public.gmane.org> wrote:

> Add support for LPTIMx_OUT triggers that can be found on some STM32
> devices. These triggers can be used then by ADC or DAC.
> Typical usage is to configure LPTimer as PWM output (via pwm-stm32-lp)
> and have synchronised analog conversions with these triggers.
> 
> Signed-off-by: Fabrice Gasnier <fabrice.gasnier-qxv4g6HH51o@public.gmane.org>
Given this can't be used as a trigger for other devices (no exposed
interrupt?) I'd expect to see a validate_device callback provided for
the trigger ops.  That would prevent other devices trying to use it.

Otherwise, looks good.

Jonathan
> ---
> Changes in v2:
> - s/Low Power/Low-Power
> - update few comments
> ---
>  drivers/iio/trigger/Kconfig                   |  11 +++
>  drivers/iio/trigger/Makefile                  |   1 +
>  drivers/iio/trigger/stm32-lptimer-trigger.c   | 110 ++++++++++++++++++++++++++
>  include/linux/iio/timer/stm32-lptim-trigger.h |  24 ++++++
>  4 files changed, 146 insertions(+)
>  create mode 100644 drivers/iio/trigger/stm32-lptimer-trigger.c
>  create mode 100644 include/linux/iio/timer/stm32-lptim-trigger.h
> 
> diff --git a/drivers/iio/trigger/Kconfig b/drivers/iio/trigger/Kconfig
> index e4d4e63..a633d2c 100644
> --- a/drivers/iio/trigger/Kconfig
> +++ b/drivers/iio/trigger/Kconfig
> @@ -24,6 +24,17 @@ config IIO_INTERRUPT_TRIGGER
>  	  To compile this driver as a module, choose M here: the
>  	  module will be called iio-trig-interrupt.
>  
> +config IIO_STM32_LPTIMER_TRIGGER
> +	tristate "STM32 Low-Power Timer Trigger"
> +	depends on MFD_STM32_LPTIMER || COMPILE_TEST
> +	help
> +	  Select this option to enable STM32 Low-Power Timer Trigger.
> +	  This can be used as trigger source for STM32 internal ADC
> +	  and/or DAC.
> +
> +	  To compile this driver as a module, choose M here: the
> +	  module will be called stm32-lptimer-trigger.
> +
>  config IIO_STM32_TIMER_TRIGGER
>  	tristate "STM32 Timer Trigger"
>  	depends on (ARCH_STM32 && OF && MFD_STM32_TIMERS) || COMPILE_TEST
> diff --git a/drivers/iio/trigger/Makefile b/drivers/iio/trigger/Makefile
> index 5c4ecd3..0a72a2a 100644
> --- a/drivers/iio/trigger/Makefile
> +++ b/drivers/iio/trigger/Makefile
> @@ -6,6 +6,7 @@
>  
>  obj-$(CONFIG_IIO_HRTIMER_TRIGGER) += iio-trig-hrtimer.o
>  obj-$(CONFIG_IIO_INTERRUPT_TRIGGER) += iio-trig-interrupt.o
> +obj-$(CONFIG_IIO_STM32_LPTIMER_TRIGGER) += stm32-lptimer-trigger.o
>  obj-$(CONFIG_IIO_STM32_TIMER_TRIGGER) += stm32-timer-trigger.o
>  obj-$(CONFIG_IIO_SYSFS_TRIGGER) += iio-trig-sysfs.o
>  obj-$(CONFIG_IIO_TIGHTLOOP_TRIGGER) += iio-trig-loop.o
> diff --git a/drivers/iio/trigger/stm32-lptimer-trigger.c b/drivers/iio/trigger/stm32-lptimer-trigger.c
> new file mode 100644
> index 0000000..bcb9aa2
> --- /dev/null
> +++ b/drivers/iio/trigger/stm32-lptimer-trigger.c
> @@ -0,0 +1,110 @@
> +/*
> + * STM32 Low-Power Timer Trigger driver
> + *
> + * Copyright (C) STMicroelectronics 2017
> + *
> + * Author: Fabrice Gasnier <fabrice.gasnier-qxv4g6HH51o@public.gmane.org>.
> + *
> + * License terms:  GNU General Public License (GPL), version 2
> + *
> + * Inspired by Benjamin Gaignard's stm32-timer-trigger driver
> + */
> +
> +#include <linux/iio/iio.h>
> +#include <linux/iio/timer/stm32-lptim-trigger.h>
> +#include <linux/iio/trigger.h>
> +#include <linux/mfd/stm32-lptimer.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +
> +/* List Low-Power Timer triggers */
> +static const char * const stm32_lptim_triggers[] = {
> +	LPTIM1_OUT,
> +	LPTIM2_OUT,
> +	LPTIM3_OUT,
> +};
> +
> +struct stm32_lptim_trigger {
> +	struct device *dev;
> +	const char *trg;
> +};
> +
> +static const struct iio_trigger_ops stm32_lptim_trigger_ops = {
> +	.owner = THIS_MODULE,
> +};
> +
> +/**
> + * is_stm32_lptim_trigger
> + * @trig: trigger to be checked
> + *
> + * return true if the trigger is a valid STM32 IIO Low-Power Timer Trigger
> + * either return false
> + */
> +bool is_stm32_lptim_trigger(struct iio_trigger *trig)
> +{
> +	return (trig->ops == &stm32_lptim_trigger_ops);
> +}
> +EXPORT_SYMBOL(is_stm32_lptim_trigger);
> +
> +static int stm32_lptim_setup_trig(struct stm32_lptim_trigger *priv)
> +{
> +	struct iio_trigger *trig;
> +
> +	trig = devm_iio_trigger_alloc(priv->dev, "%s", priv->trg);
> +	if  (!trig)
> +		return -ENOMEM;
> +
> +	trig->dev.parent = priv->dev->parent;
> +	trig->ops = &stm32_lptim_trigger_ops;
> +	iio_trigger_set_drvdata(trig, priv);
> +
> +	return devm_iio_trigger_register(priv->dev, trig);
> +}
> +
> +static int stm32_lptim_trigger_probe(struct platform_device *pdev)
> +{
> +	struct stm32_lptim_trigger *priv;
> +	u32 index;
> +	int ret;
> +
> +	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
> +	if (!priv)
> +		return -ENOMEM;
> +
> +	if (of_property_read_u32(pdev->dev.of_node, "reg", &index))
> +		return -EINVAL;
> +
> +	if (index >= ARRAY_SIZE(stm32_lptim_triggers))
> +		return -EINVAL;
> +
> +	priv->dev = &pdev->dev;
> +	priv->trg = stm32_lptim_triggers[index];
> +
> +	ret = stm32_lptim_setup_trig(priv);
> +	if (ret)
> +		return ret;
> +
> +	platform_set_drvdata(pdev, priv);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id stm32_lptim_trig_of_match[] = {
> +	{ .compatible = "st,stm32-lptimer-trigger", },
> +	{},
> +};
> +MODULE_DEVICE_TABLE(of, stm32_lptim_trig_of_match);
> +
> +static struct platform_driver stm32_lptim_trigger_driver = {
> +	.probe = stm32_lptim_trigger_probe,
> +	.driver = {
> +		.name = "stm32-lptimer-trigger",
> +		.of_match_table = stm32_lptim_trig_of_match,
> +	},
> +};
> +module_platform_driver(stm32_lptim_trigger_driver);
> +
> +MODULE_AUTHOR("Fabrice Gasnier <fabrice.gasnier-qxv4g6HH51o@public.gmane.org>");
> +MODULE_ALIAS("platform:stm32-lptimer-trigger");
> +MODULE_DESCRIPTION("STMicroelectronics STM32 LPTIM trigger driver");
> +MODULE_LICENSE("GPL v2");
> diff --git a/include/linux/iio/timer/stm32-lptim-trigger.h b/include/linux/iio/timer/stm32-lptim-trigger.h
> new file mode 100644
> index 0000000..cb795b1
> --- /dev/null
> +++ b/include/linux/iio/timer/stm32-lptim-trigger.h
> @@ -0,0 +1,24 @@
> +/*
> + * Copyright (C) STMicroelectronics 2017
> + *
> + * Author: Fabrice Gasnier <fabrice.gasnier-qxv4g6HH51o@public.gmane.org>
> + *
> + * License terms:  GNU General Public License (GPL), version 2
> + */
> +
> +#ifndef _STM32_LPTIM_TRIGGER_H_
> +#define _STM32_LPTIM_TRIGGER_H_
> +
> +#define LPTIM1_OUT	"lptim1_out"
> +#define LPTIM2_OUT	"lptim2_out"
> +#define LPTIM3_OUT	"lptim3_out"
> +
> +#if IS_ENABLED(CONFIG_IIO_STM32_LPTIMER_TRIGGER)
> +bool is_stm32_lptim_trigger(struct iio_trigger *trig);
> +#else
> +static inline bool is_stm32_lptim_trigger(struct iio_trigger *trig)
> +{
> +	return false;
> +}
> +#endif
> +#endif