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

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

On Mon, 26 Jun 2017 18:41:36 +0200
Fabrice Gasnier <fabrice.gasnier-qxv4g6HH51o@public.gmane.org> wrote:

> On 06/24/2017 10:13 PM, Jonathan Cameron wrote:
> > 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.  
> 
> Hi Jonathan,
> 
> This is something I had in mind also earlier. Only thing is...
> Basically, this is limiting: when trigger poll happens on device side
> (e.g. ADC), another device could use same trigger. But I admit this
> looks like corner case.
> 
> I'll add it in next version, with additional patch for ADC part to
> validate it's a valid device (No DAC yet).
> I think I'll use INDIO_HARDWARE_TRIGGERED mode:
> - in adc driver: indio_dev->modes |= INDIO_HARDWARE_TRIGGERED;
> - in lptimer: if (indio_dev->modes & INDIO_HARDWARE_TRIGGERED)...
That may not be enough in of itself.  Could be other hardware
triggered elements on the platform (quite likely with these
stm parts!)

J
> 
> > 
> > Otherwise, looks good.  
> 
> Many thanks for your review.
> Best Regards,
> Fabrice
> 
> > 
> > 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  
> >