Re: [PATCH v6 6/8] IIO: add STM32 timer trigger driver

[Jonathan Cameron]

On 09/12/16 14:15, Benjamin Gaignard wrote:
> Timers IPs can be used to generate triggers for other IPs like
> DAC, ADC or other timers.
> Each trigger may result of timer internals signals like counter enable,
> reset or edge, this configuration could be done through "master_mode"
> device attribute.
> 
> A timer device could be triggered by other timers, we use the trigger
> name and is_stm32_iio_timer_trigger() function to distinguish them
> and configure IP input switch.
> 
> Timer may also decide on which event (edge, level) they could
> be activated by a trigger, this configuration is done by writing in
> "slave_mode" device attribute.
> 
> Since triggers could also be used by DAC or ADC their names are defined
> in include/ nux/iio/timer/stm32-timer-trigger.h so those IPs will be able
> to configure themselves in valid_trigger function
> 
> Trigger have a "sampling_frequency" attribute which allow to configure
> timer sampling frequency without using PWM interface
> 
> version 5:
> - simplify tables of triggers
> - only create an IIO device when needed
> 
> version 4:
> - get triggers configuration from "reg" in DT
> - add tables of triggers
> - sampling frequency is enable/disable when writing in trigger
>   sampling_frequency attribute
> - no more use of interruptions
> 
> version 3:
> - change compatible to "st,stm32-timer-trigger"
> - fix attributes access right
> - use string instead of int for master_mode and slave_mode
> - document device attributes in sysfs-bus-iio-timer-stm32
> 
> version 2:
> - keep only one compatible
> - use st,input-triggers-names and st,output-triggers-names
>   to know which triggers are accepted and/or create by the device
Firstly, sorry it has taken me so long to get back to this.

I'm still not keen on this use of iio_device elements just to act as
glue between triggers.  I think we need to work out a more light weight
way to do this.  As you are only using them for validation and to provide
somewhere to hang the control attibutes off, there is nothing stopping us
moving that over to the iio_trigger instead which would avoid the messy
duality going on here.

I might still be missing something though!

You would only I think need 3 attributes

parrent_trigger
and something like your master_mode and slave_mode attributes.

The parrent_trigger would need some validation etc, but if we keep it
within this driver initially that won't be hard to do. Checking the device
parent matches will do most of it.

Jonathan
> 
> Signed-off-by: Benjamin Gaignard <benjamin.gaignard@xxxxxx>
> ---
>  .../ABI/testing/sysfs-bus-iio-timer-stm32          |  55 +++
>  drivers/iio/Kconfig                                |   2 +-
>  drivers/iio/Makefile                               |   1 +
>  drivers/iio/timer/Kconfig                          |  13 +
>  drivers/iio/timer/Makefile                         |   1 +
>  drivers/iio/timer/stm32-timer-trigger.c            | 466 +++++++++++++++++++++
>  drivers/iio/trigger/Kconfig                        |   1 -
>  include/linux/iio/timer/stm32-timer-trigger.h      |  62 +++
>  8 files changed, 599 insertions(+), 2 deletions(-)
>  create mode 100644 Documentation/ABI/testing/sysfs-bus-iio-timer-stm32
>  create mode 100644 drivers/iio/timer/Kconfig
>  create mode 100644 drivers/iio/timer/Makefile
>  create mode 100644 drivers/iio/timer/stm32-timer-trigger.c
>  create mode 100644 include/linux/iio/timer/stm32-timer-trigger.h
> 
> diff --git a/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32 b/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32
> new file mode 100644
> index 0000000..26583dd
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32
> @@ -0,0 +1,55 @@
> +What:		/sys/bus/iio/devices/iio:deviceX/master_mode_available
> +KernelVersion:	4.10
> +Contact:	benjamin.gaignard@xxxxxx
> +Description:
> +		Reading returns the list possible master modes which are:
> +		- "reset"     :	The UG bit from the TIMx_EGR register is used as trigger output (TRGO).
> +		- "enable"    : The Counter Enable signal CNT_EN is used as trigger output.
> +		- "update"    : The update event is selected as trigger output.
> +				For instance a master timer can then be used as a prescaler for a slave timer.
> +		- "compare_pulse" : The trigger output send a positive pulse when the CC1IF flag is to be set.
> +		- "OC1REF"    : OC1REF signal is used as trigger output.
> +		- "OC2REF"    : OC2REF signal is used as trigger output.
> +		- "OC3REF"    : OC3REF signal is used as trigger output.
> +		- "OC4REF"    : OC4REF signal is used as trigger output.
> +
> +What:		/sys/bus/iio/devices/iio:deviceX/master_mode
> +KernelVersion:	4.10
> +Contact:	benjamin.gaignard@xxxxxx
> +Description:
> +		Reading returns the current master modes.
> +		Writing set the master mode
> +
> +What:		/sys/bus/iio/devices/iio:deviceX/slave_mode_available
> +KernelVersion:	4.10
> +Contact:	benjamin.gaignard@xxxxxx
> +Description:
> +		Reading returns the list possible slave modes which are:
> +		- "disabled"  : The prescaler is clocked directly by the internal clock.
> +		- "encoder_1" : Counter counts up/down on TI2FP1 edge depending on TI1FP2 level.
> +		- "encoder_2" : Counter counts up/down on TI1FP2 edge depending on TI2FP1 level.
> +		- "encoder_3" : Counter counts up/down on both TI1FP1 and TI2FP2 edges depending
> +				on the level of the other input.
> +		- "reset"     : Rising edge of the selected trigger input reinitializes the counter
> +				and generates an update of the registers.
> +		- "gated"     : The counter clock is enabled when the trigger input is high.
> +				The counter stops (but is not reset) as soon as the trigger becomes low.
> +				Both start and stop of the counter are controlled.
> +		- "trigger"   : The counter starts at a rising edge of the trigger TRGI (but it is not
> +				reset). Only the start of the counter is controlled.
> +		- "external_clock": Rising edges of the selected trigger (TRGI) clock the counter.
> +
> +What:		/sys/bus/iio/devices/iio:deviceX/slave_mode
> +KernelVersion:	4.10
> +Contact:	benjamin.gaignard@xxxxxx
> +Description:
> +		Reading returns the current slave mode.
> +		Writing set the slave mode
> +
> +What:		/sys/bus/iio/devices/triggerX/sampling_frequency
> +KernelVersion:	4.10
> +Contact:	benjamin.gaignard@xxxxxx
> +Description:
> +		Reading returns the current sampling frequency.
> +		Writing an value different of 0 set and start sampling.
> +		Writing 0 stop sampling.
> diff --git a/drivers/iio/Kconfig b/drivers/iio/Kconfig
> index 6743b18..2de2a80 100644
> --- a/drivers/iio/Kconfig
> +++ b/drivers/iio/Kconfig
> @@ -90,5 +90,5 @@ source "drivers/iio/potentiometer/Kconfig"
>  source "drivers/iio/pressure/Kconfig"
>  source "drivers/iio/proximity/Kconfig"
>  source "drivers/iio/temperature/Kconfig"
> -
> +source "drivers/iio/timer/Kconfig"
>  endif # IIO
> diff --git a/drivers/iio/Makefile b/drivers/iio/Makefile
> index 87e4c43..b797c08 100644
> --- a/drivers/iio/Makefile
> +++ b/drivers/iio/Makefile
> @@ -32,4 +32,5 @@ obj-y += potentiometer/
>  obj-y += pressure/
>  obj-y += proximity/
>  obj-y += temperature/
> +obj-y += timer/
>  obj-y += trigger/
> diff --git a/drivers/iio/timer/Kconfig b/drivers/iio/timer/Kconfig
> new file mode 100644
> index 0000000..e3c21f2
> --- /dev/null
> +++ b/drivers/iio/timer/Kconfig
> @@ -0,0 +1,13 @@
> +#
> +# Timers drivers
> +
> +menu "Timers"
> +
> +config IIO_STM32_TIMER_TRIGGER
> +	tristate "STM32 Timer Trigger"
> +	depends on (ARCH_STM32 && OF && MFD_STM32_TIMERS) || COMPILE_TEST
> +	select IIO_TRIGGERED_EVENT
> +	help
> +	  Select this option to enable STM32 Timer Trigger
> +
> +endmenu
> diff --git a/drivers/iio/timer/Makefile b/drivers/iio/timer/Makefile
> new file mode 100644
> index 0000000..4ad95ec9
> --- /dev/null
> +++ b/drivers/iio/timer/Makefile
> @@ -0,0 +1 @@
> +obj-$(CONFIG_IIO_STM32_TIMER_TRIGGER) += stm32-timer-trigger.o
> diff --git a/drivers/iio/timer/stm32-timer-trigger.c b/drivers/iio/timer/stm32-timer-trigger.c
> new file mode 100644
> index 0000000..8d16e8f
> --- /dev/null
> +++ b/drivers/iio/timer/stm32-timer-trigger.c
> @@ -0,0 +1,466 @@
> +/*
> + * Copyright (C) STMicroelectronics 2016
> + *
> + * Author: Benjamin Gaignard <benjamin.gaignard@xxxxxx>
> + *
> + * License terms:  GNU General Public License (GPL), version 2
> + */
> +
> +#include <linux/iio/iio.h>
> +#include <linux/iio/sysfs.h>
> +#include <linux/iio/timer/stm32-timer-trigger.h>
> +#include <linux/iio/trigger.h>
> +#include <linux/iio/triggered_event.h>
> +#include <linux/interrupt.h>
> +#include <linux/mfd/stm32-timers.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +
> +#define MAX_TRIGGERS 6
> +#define MAX_VALIDS 5
> +
> +/* List the triggers created by each timer */
> +static const void *triggers_table[][MAX_TRIGGERS] = {
> +	{ TIM1_TRGO, TIM1_CH1, TIM1_CH2, TIM1_CH3, TIM1_CH4,},
> +	{ TIM2_TRGO, TIM2_CH1, TIM2_CH2, TIM2_CH3, TIM2_CH4,},
> +	{ TIM3_TRGO, TIM3_CH1, TIM3_CH2, TIM3_CH3, TIM3_CH4,},
> +	{ TIM4_TRGO, TIM4_CH1, TIM4_CH2, TIM4_CH3, TIM4_CH4,},
> +	{ TIM5_TRGO, TIM5_CH1, TIM5_CH2, TIM5_CH3, TIM5_CH4,},
> +	{ TIM6_TRGO,},
> +	{ TIM7_TRGO,},
> +	{ TIM8_TRGO, TIM8_CH1, TIM8_CH2, TIM8_CH3, TIM8_CH4,},
> +	{ TIM9_TRGO, TIM9_CH1, TIM9_CH2,},
> +	{ TIM12_TRGO, TIM12_CH1, TIM12_CH2,},
> +};
> +
> +/* List the triggers accepted by each timer */
> +static const void *valids_table[][MAX_VALIDS] = {
> +	{ TIM5_TRGO, TIM2_TRGO, TIM4_TRGO, TIM3_TRGO,},
> +	{ TIM1_TRGO, TIM8_TRGO, TIM3_TRGO, TIM4_TRGO,},
> +	{ TIM1_TRGO, TIM8_TRGO, TIM5_TRGO, TIM4_TRGO,},
> +	{ TIM1_TRGO, TIM2_TRGO, TIM3_TRGO, TIM8_TRGO,},
> +	{ TIM2_TRGO, TIM3_TRGO, TIM4_TRGO, TIM8_TRGO,},
> +	{ }, /* timer 6 */
> +	{ }, /* timer 7 */
> +	{ TIM1_TRGO, TIM2_TRGO, TIM4_TRGO, TIM5_TRGO,},
> +	{ TIM2_TRGO, TIM3_TRGO,},
> +	{ TIM4_TRGO, TIM5_TRGO,},
> +};
> +
> +struct stm32_timer_trigger {
> +	struct device *dev;
> +	struct regmap *regmap;
> +	struct clk *clk;
> +	u32 max_arr;
> +	const void *triggers;
> +	const void *valids;
> +};
> +
> +static int stm32_timer_start(struct stm32_timer_trigger *priv,
> +			     unsigned int frequency)
> +{
> +	unsigned long long prd, div;
> +	int prescaler = 0;
> +	u32 ccer, cr1;
> +
> +	/* Period and prescaler values depends of clock rate */
> +	div = (unsigned long long)clk_get_rate(priv->clk);
> +
> +	do_div(div, frequency);
> +
> +	prd = div;
> +
> +	/*
> +	 * Increase prescaler value until we get a result that fit
> +	 * with auto reload register maximum value.
> +	 */
> +	while (div > priv->max_arr) {
> +		prescaler++;
> +		div = prd;
> +		do_div(div, (prescaler + 1));
> +	}
> +	prd = div;
> +
> +	if (prescaler > MAX_TIM_PSC) {
> +		dev_err(priv->dev, "prescaler exceeds the maximum value\n");
> +		return -EINVAL;
> +	}
> +
> +	/* Check if nobody else use the timer */
> +	regmap_read(priv->regmap, TIM_CCER, &ccer);
> +	if (ccer & TIM_CCER_CCXE)
> +		return -EBUSY;
> +
> +	regmap_read(priv->regmap, TIM_CR1, &cr1);
> +	if (!(cr1 & TIM_CR1_CEN))
> +		clk_enable(priv->clk);
> +
> +	regmap_write(priv->regmap, TIM_PSC, prescaler);
> +	regmap_write(priv->regmap, TIM_ARR, prd - 1);
> +	regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_ARPE, TIM_CR1_ARPE);
> +
> +	/* Force master mode to update mode */
> +	regmap_update_bits(priv->regmap, TIM_CR2, TIM_CR2_MMS, 0x20);
> +
> +	/* Make sure that registers are updated */
> +	regmap_update_bits(priv->regmap, TIM_EGR, TIM_EGR_UG, TIM_EGR_UG);
> +
> +	/* Enable controller */
> +	regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_CEN, TIM_CR1_CEN);
> +
> +	return 0;
> +}
> +
> +static void stm32_timer_stop(struct stm32_timer_trigger *priv)
> +{
> +	u32 ccer, cr1;
> +
> +	regmap_read(priv->regmap, TIM_CCER, &ccer);
> +	if (ccer & TIM_CCER_CCXE)
> +		return;
> +
> +	regmap_read(priv->regmap, TIM_CR1, &cr1);
> +	if (cr1 & TIM_CR1_CEN)
> +		clk_disable(priv->clk);
> +
> +	/* Stop timer */
> +	regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_CEN, 0);
> +	regmap_write(priv->regmap, TIM_PSC, 0);
> +	regmap_write(priv->regmap, TIM_ARR, 0);
> +}
> +
> +static ssize_t stm32_tt_store_frequency(struct device *dev,
> +					struct device_attribute *attr,
> +					const char *buf, size_t len)
> +{
> +	struct iio_trigger *trig = to_iio_trigger(dev);
> +	struct stm32_timer_trigger *priv = iio_trigger_get_drvdata(trig);
> +	unsigned int freq;
> +	int ret;
> +
> +	ret = kstrtouint(buf, 10, &freq);
> +	if (ret)
> +		return ret;
> +
> +	if (freq == 0) {
> +		stm32_timer_stop(priv);
> +	} else {
> +		ret = stm32_timer_start(priv, freq);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	return len;
> +}
> +
> +static ssize_t stm32_tt_read_frequency(struct device *dev,
> +				       struct device_attribute *attr, char *buf)
> +{
> +	struct iio_trigger *trig = to_iio_trigger(dev);
> +	struct stm32_timer_trigger *priv = iio_trigger_get_drvdata(trig);
> +	u32 psc, arr, cr1;
> +	unsigned long long freq = 0;
> +
> +	regmap_read(priv->regmap, TIM_CR1, &cr1);
> +	regmap_read(priv->regmap, TIM_PSC, &psc);
> +	regmap_read(priv->regmap, TIM_ARR, &arr);
> +
> +	if (psc && arr && (cr1 & TIM_CR1_CEN)) {
> +		freq = (unsigned long long)clk_get_rate(priv->clk);
> +		do_div(freq, psc);
> +		do_div(freq, arr);
> +	}
> +
> +	return sprintf(buf, "%d\n", (unsigned int)freq);
> +}
> +
> +static IIO_DEV_ATTR_SAMP_FREQ(0660,
> +			      stm32_tt_read_frequency,
> +			      stm32_tt_store_frequency);
> +
> +static struct attribute *stm32_trigger_attrs[] = {
> +	&iio_dev_attr_sampling_frequency.dev_attr.attr,
> +	NULL,
> +};
> +
> +static const struct attribute_group stm32_trigger_attr_group = {
> +	.attrs = stm32_trigger_attrs,
> +};
> +
> +static const struct attribute_group *stm32_trigger_attr_groups[] = {
> +	&stm32_trigger_attr_group,
> +	NULL,
> +};
> +
> +static char *master_mode_table[] = {
> +	"reset",
> +	"enable",
> +	"update",
> +	"compare_pulse",
> +	"OC1REF",
> +	"OC2REF",
> +	"OC3REF",
> +	"OC4REF"
> +};
> +
> +static ssize_t stm32_tt_show_master_mode(struct device *dev,
> +					 struct device_attribute *attr,
> +					 char *buf)
> +{
> +	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
> +	struct stm32_timer_trigger *priv = iio_priv(indio_dev);
> +	u32 cr2;
> +
> +	regmap_read(priv->regmap, TIM_CR2, &cr2);
> +	cr2 = (cr2 & TIM_CR2_MMS) >> TIM_CR2_MMS_SHIFT;
> +
> +	return snprintf(buf, PAGE_SIZE, "%s\n", master_mode_table[cr2]);
> +}
> +
> +static ssize_t stm32_tt_store_master_mode(struct device *dev,
> +					  struct device_attribute *attr,
> +					  const char *buf, size_t len)
> +{
> +	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
> +	struct stm32_timer_trigger *priv = iio_priv(indio_dev);
> +	int i;
> +
> +	for (i = 0; i < ARRAY_SIZE(master_mode_table); i++) {
> +		if (!strncmp(master_mode_table[i], buf,
> +			     strlen(master_mode_table[i]))) {
> +			regmap_update_bits(priv->regmap, TIM_CR2,
> +					   TIM_CR2_MMS, i << TIM_CR2_MMS_SHIFT);
> +			return len;
> +		}
> +	}
> +
> +	return -EINVAL;
> +}
> +
> +static IIO_CONST_ATTR(master_mode_available,
> +	"reset enable update compare_pulse OC1REF OC2REF OC3REF OC4REF");
> +
> +static IIO_DEVICE_ATTR(master_mode, 0660,
> +		       stm32_tt_show_master_mode,
> +		       stm32_tt_store_master_mode,
> +		       0);
> +
> +static char *slave_mode_table[] = {
> +	"disabled",
> +	"encoder_1",
> +	"encoder_2",
> +	"encoder_3",
> +	"reset",
> +	"gated",
> +	"trigger",
> +	"external_clock",
> +};
> +
> +static ssize_t stm32_tt_show_slave_mode(struct device *dev,
> +					struct device_attribute *attr,
> +					char *buf)
> +{
> +	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
> +	struct stm32_timer_trigger *priv = iio_priv(indio_dev);
> +	u32 smcr;
> +
> +	regmap_read(priv->regmap, TIM_SMCR, &smcr);
> +	smcr &= TIM_SMCR_SMS;
> +
> +	return snprintf(buf, PAGE_SIZE, "%s\n", slave_mode_table[smcr]);
> +}
> +
> +static ssize_t stm32_tt_store_slave_mode(struct device *dev,
> +					 struct device_attribute *attr,
> +					 const char *buf, size_t len)
> +{
> +	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
> +	struct stm32_timer_trigger *priv = iio_priv(indio_dev);
> +	int i;
> +
> +	for (i = 0; i < ARRAY_SIZE(slave_mode_table); i++) {
> +		if (!strncmp(slave_mode_table[i], buf,
> +			     strlen(slave_mode_table[i]))) {
> +			regmap_update_bits(priv->regmap,
> +					   TIM_SMCR, TIM_SMCR_SMS, i);
> +			return len;
> +		}
> +	}
> +
> +	return -EINVAL;
> +}
> +
> +static IIO_CONST_ATTR(slave_mode_available,
> +"disabled encoder_1 encoder_2 encoder_3 reset gated trigger external_clock");
> +
> +static IIO_DEVICE_ATTR(slave_mode, 0660,
> +		       stm32_tt_show_slave_mode,
> +		       stm32_tt_store_slave_mode,
> +		       0);
> +
> +static struct attribute *stm32_timer_attrs[] = {
> +	&iio_dev_attr_master_mode.dev_attr.attr,
> +	&iio_const_attr_master_mode_available.dev_attr.attr,
> +	&iio_dev_attr_slave_mode.dev_attr.attr,
> +	&iio_const_attr_slave_mode_available.dev_attr.attr,
> +	NULL,
> +};
> +
> +static const struct attribute_group stm32_timer_attr_group = {
> +	.attrs = stm32_timer_attrs,
> +};
> +
> +static const struct iio_trigger_ops timer_trigger_ops = {
> +	.owner = THIS_MODULE,
> +};
> +
> +static int stm32_setup_iio_triggers(struct stm32_timer_trigger *priv)
> +{
> +	int ret;
> +	const char * const *cur = priv->triggers;
> +
> +	while (cur && *cur) {
> +		struct iio_trigger *trig;
> +
> +		trig = devm_iio_trigger_alloc(priv->dev, "%s", *cur);
> +		if  (!trig)
> +			return -ENOMEM;
> +
> +		trig->dev.parent = priv->dev->parent;
> +		trig->ops = &timer_trigger_ops;
> +		trig->dev.groups = stm32_trigger_attr_groups;
> +		iio_trigger_set_drvdata(trig, priv);
> +
> +		ret = devm_iio_trigger_register(priv->dev, trig);
> +		if (ret)
> +			return ret;
> +		cur++;
> +	}
> +
> +	return 0;
> +}
> +
> +/**
> + * is_stm32_timer_trigger
> + * @trig: trigger to be checked
> + *
> + * return true if the trigger is a valid stm32 iio timer trigger
> + * either return false
> + */
> +bool is_stm32_timer_trigger(struct iio_trigger *trig)
> +{
> +	return (trig->ops == &timer_trigger_ops);
> +}
> +EXPORT_SYMBOL(is_stm32_timer_trigger);
> +
> +static int stm32_validate_trigger(struct iio_dev *indio_dev,
> +				  struct iio_trigger *trig)
> +{
> +	struct stm32_timer_trigger *priv = iio_priv(indio_dev);
> +	const char * const *cur = priv->valids;
> +	unsigned int i = 0;
> +
> +	if (!is_stm32_timer_trigger(trig))
> +		return -EINVAL;
> +
> +	while (cur && *cur) {
> +		if (!strncmp(trig->name, *cur, strlen(trig->name))) {
> +			regmap_update_bits(priv->regmap,
> +					   TIM_SMCR, TIM_SMCR_TS,
> +					   i << TIM_SMCR_TS_SHIFT);
> +			return 0;
> +		}
> +		cur++;
> +		i++;
> +	}
> +
> +	return -EINVAL;
> +}
> +
> +static const struct iio_info stm32_trigger_info = {
> +	.driver_module = THIS_MODULE,
> +	.validate_trigger = stm32_validate_trigger,
> +	.attrs = &stm32_timer_attr_group,
> +};
> +
> +static struct stm32_timer_trigger *stm32_setup_iio_device(struct device *dev)
> +{
> +	struct iio_dev *indio_dev;
> +	int ret;
> +
> +	indio_dev = devm_iio_device_alloc(dev,
> +					  sizeof(struct stm32_timer_trigger));
> +	if (!indio_dev)
> +		return NULL;
> +
> +	indio_dev->name = dev_name(dev);
> +	indio_dev->dev.parent = dev;
> +	indio_dev->info = &stm32_trigger_info;
> +	indio_dev->modes = INDIO_EVENT_TRIGGERED;
> +	indio_dev->num_channels = 0;
> +	indio_dev->dev.of_node = dev->of_node;
> +
> +	ret = devm_iio_device_register(dev, indio_dev);
> +	if (ret)
> +		return NULL;
> +
> +	return iio_priv(indio_dev);
> +}
> +
> +static int stm32_timer_trigger_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct stm32_timer_trigger *priv;
> +	struct stm32_timers *ddata = dev_get_drvdata(pdev->dev.parent);
> +	unsigned int index;
> +	int ret;
> +
> +	if (of_property_read_u32(dev->of_node, "reg", &index))
> +		return -EINVAL;
> +
> +	if (index >= ARRAY_SIZE(triggers_table))
> +		return -EINVAL;
> +
> +	/* Create an IIO device only if we have triggers to be validated */
> +	if (*valids_table[index])
> +		priv = stm32_setup_iio_device(dev);

I still don't like this. Really feels like we shouldn't be creating an
iio device with all the bagage that carries just to allow us to do the
trigger trees.  We ought to have a much more light weight solution for this
functionality - we aren't typically even using the interrupt tree stuff
that the triggers for devices are all really about.

A simpler approach of allowing each trigger the option of a parent seems like
it would be cleaner.  Could be done entirely within this driver in the first
instance.  Basically it would just look like your master and slave attributes
but have those under triggerX not iio:deviceX.

We can work out how to make it more generic later - including perhaps the
option to trigger from triggers outside this driver, using some parallel
infrastructure to the device triggering.


> +	else
> +		priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
> +
> +	if (!priv)
> +		return -ENOMEM;
> +
> +	priv->dev = dev;
> +	priv->regmap = ddata->regmap;
> +	priv->clk = ddata->clk;
> +	priv->max_arr = ddata->max_arr;
> +	priv->triggers = triggers_table[index];
> +	priv->valids = valids_table[index];
> +
> +	ret = stm32_setup_iio_triggers(priv);
> +	if (ret)
> +		return ret;
> +
> +	platform_set_drvdata(pdev, priv);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id stm32_trig_of_match[] = {
> +	{ .compatible = "st,stm32-timer-trigger", },
> +	{ /* end node */ },
> +};
> +MODULE_DEVICE_TABLE(of, stm32_trig_of_match);
> +
> +static struct platform_driver stm32_timer_trigger_driver = {
> +	.probe = stm32_timer_trigger_probe,
> +	.driver = {
> +		.name = "stm32-timer-trigger",
> +		.of_match_table = stm32_trig_of_match,
> +	},
> +};
> +module_platform_driver(stm32_timer_trigger_driver);
> +
> +MODULE_ALIAS("platform: stm32-timer-trigger");
> +MODULE_DESCRIPTION("STMicroelectronics STM32 Timer Trigger driver");
> +MODULE_LICENSE("GPL v2");
> diff --git a/drivers/iio/trigger/Kconfig b/drivers/iio/trigger/Kconfig
> index 809b2e7..f2af4fe 100644
> --- a/drivers/iio/trigger/Kconfig
> +++ b/drivers/iio/trigger/Kconfig
> @@ -46,5 +46,4 @@ config IIO_SYSFS_TRIGGER
>  
>  	  To compile this driver as a module, choose M here: the
>  	  module will be called iio-trig-sysfs.
> -
Clean this up.
>  endmenu
> diff --git a/include/linux/iio/timer/stm32-timer-trigger.h b/include/linux/iio/timer/stm32-timer-trigger.h
> new file mode 100644
> index 0000000..55535ae
> --- /dev/null
> +++ b/include/linux/iio/timer/stm32-timer-trigger.h
> @@ -0,0 +1,62 @@
> +/*
> + * Copyright (C) STMicroelectronics 2016
> + *
> + * Author: Benjamin Gaignard <benjamin.gaignard@xxxxxx>
> + *
> + * License terms:  GNU General Public License (GPL), version 2
> + */
> +
> +#ifndef _STM32_TIMER_TRIGGER_H_
> +#define _STM32_TIMER_TRIGGER_H_
> +
> +#define TIM1_TRGO	"tim1_trgo"
> +#define TIM1_CH1	"tim1_ch1"
> +#define TIM1_CH2	"tim1_ch2"
> +#define TIM1_CH3	"tim1_ch3"
> +#define TIM1_CH4	"tim1_ch4"
> +
> +#define TIM2_TRGO	"tim2_trgo"
> +#define TIM2_CH1	"tim2_ch1"
> +#define TIM2_CH2	"tim2_ch2"
> +#define TIM2_CH3	"tim2_ch3"
> +#define TIM2_CH4	"tim2_ch4"
> +
> +#define TIM3_TRGO	"tim3_trgo"
> +#define TIM3_CH1	"tim3_ch1"
> +#define TIM3_CH2	"tim3_ch2"
> +#define TIM3_CH3	"tim3_ch3"
> +#define TIM3_CH4	"tim3_ch4"
> +
> +#define TIM4_TRGO	"tim4_trgo"
> +#define TIM4_CH1	"tim4_ch1"
> +#define TIM4_CH2	"tim4_ch2"
> +#define TIM4_CH3	"tim4_ch3"
> +#define TIM4_CH4	"tim4_ch4"
> +
> +#define TIM5_TRGO	"tim5_trgo"
> +#define TIM5_CH1	"tim5_ch1"
> +#define TIM5_CH2	"tim5_ch2"
> +#define TIM5_CH3	"tim5_ch3"
> +#define TIM5_CH4	"tim5_ch4"
> +
> +#define TIM6_TRGO	"tim6_trgo"
> +
> +#define TIM7_TRGO	"tim7_trgo"
> +
> +#define TIM8_TRGO	"tim8_trgo"
> +#define TIM8_CH1	"tim8_ch1"
> +#define TIM8_CH2	"tim8_ch2"
> +#define TIM8_CH3	"tim8_ch3"
> +#define TIM8_CH4	"tim8_ch4"
> +
> +#define TIM9_TRGO	"tim9_trgo"
> +#define TIM9_CH1	"tim9_ch1"
> +#define TIM9_CH2	"tim9_ch2"
> +
> +#define TIM12_TRGO	"tim12_trgo"
> +#define TIM12_CH1	"tim12_ch1"
> +#define TIM12_CH2	"tim12_ch2"
> +
> +bool is_stm32_timer_trigger(struct iio_trigger *trig);
> +
> +#endif
>