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

[Fabrice Gasnier <fabrice.gasnier@st.com>]

On 06/24/2017 10:13 PM, Jonathan Cameron wrote:
> On Wed, 21 Jun 2017 16:30:13 +0200
> Fabrice Gasnier <fabrice.gasnier@st.com> 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@st.com>
> 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)...

> 
> 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@st.com>.
>> + *
>> + * 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@st.com>");
>> +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@st.com>
>> + *
>> + * 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
>