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Message-ID: <CA+M3ks60mfq6Pc8LGJi=qJ7Eu_LBMu2OWOp5OZDc8X6bHnC-3w@mail.gmail.com>
Date: Sun, 26 Feb 2017 15:59:11 +0100
From: Benjamin Gaignard <benjamin.gaignard@...aro.org>
To: Jonathan Cameron <jic23@...nel.org>
Cc: Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
linux-iio@...r.kernel.org, Hartmut Knaack <knaack.h@....de>,
Lars-Peter Clausen <lars@...afoo.de>,
Peter Meerwald-Stadler <pmeerw@...erw.net>,
Fabrice Gasnier <fabrice.gasnier@...com>,
Linaro Kernel Mailman List <linaro-kernel@...ts.linaro.org>,
Benjamin Gaignard <benjamin.gaignard@...com>
Subject: Re: [PATCH v3 2/2] iio: stm32 trigger: Implement parent trigger feature
2017-02-25 18:53 GMT+01:00 Jonathan Cameron <jic23@...nel.org>:
> On 24/02/17 14:48, Benjamin Gaignard wrote:
>> Add validate_trigger function in iio_trigger_ops and
>> dev_attr_parent_trigger into trigger attribute group to be able
>> to accept triggers as parents.
>>
>> Introduce an IIO device with one IIO_COUNT channel to get access
>> to counter value. Counter directions can be set/get when writing/reading
>> /sys/bus/iio/devices/iio:deviceX/in_count0_count_direction.
>>
>> The hardware have multiple way to use inputs edges and levels to
>> performing counting, those different modes are exposed in:
>> /sys/bus/iio/devices/iio:deviceX/in_count_count_mode_available.
> Funny though it sounds, this is to general to generalize.
> See below.
>>
>> "trigger_rising_edges" mode is automatically set when a valid
>> parent trigger is set.
> We still have an issue of two overlapping concepts here, that
> of a clock and that of a parent trigger. Perhaps it's valid
> to have a clock set to be the parent trigger, but that is
> kind of the odd case rather than the normal use of
> parent triggers (in my head at least :)
>
> So what we end up with here is something we have kind of messed
> around with before...
>
> An event acting as a trigger.
> Conceptually your 'preset' occurring is an event in IIO terms
> (there is on going work to present exactly that event to userspace
> for the other encoder driver we have).
>
> That event is then acting as a trigger, even if that trigger
> is not 'visible' as such to userspace.
>
> This event as trigger is something we have messed around with
> from the very start but never formalized. It is one of the things
> that would make good use of an inkernel consumer interface
> for events. If we had one of those, a tiny driver and a bit of
> configfs magic interface and we'd be able to use any event as
> a trigger.
>
> Hence I rather like this. You could say it fits with my
> world view ;)
>
> Only remaining question to my mind is whether we need to make that
> presence of an 'event' explicit? Doesn't necessarily have
> to happen now, but if it existed in some sense it might make
> it easier for generic userspace to interpret what is going on.
>
> Maybe something for the future.
>
> Anyhow, still some work to do here, but moving in a viable
> direction (I think) so keep up the good work!
An other way is to get a device which is a trigger consumer without
having buffer or
>
> Jonathan
>>
>> Signed-off-by: Benjamin Gaignard <benjamin.gaignard@...com>
>>
>> version 2:
>> - use dev_attr_parent_trigger
>> - improve slave modes documentation
>>
>> version 3:
>> - add one channel to get counter raw value
>> ---
>> .../ABI/testing/sysfs-bus-iio-timer-stm32 | 63 +++++
>> drivers/iio/trigger/stm32-timer-trigger.c | 256 ++++++++++++++++++++-
>> include/linux/mfd/stm32-timers.h | 2 +
>> 3 files changed, 315 insertions(+), 6 deletions(-)
>>
>> diff --git a/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32 b/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32
>> index 6534a60..63852a9 100644
>> --- a/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32
>> +++ b/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32
>> @@ -27,3 +27,66 @@ Description:
>> Reading returns the current sampling frequency.
>> Writing an value different of 0 set and start sampling.
>> Writing 0 stop sampling.
>> +
>> +What: /sys/bus/iio/devices/iio:deviceX/in_count0_raw
>> +KernelVersion: 4.12
>> +Contact: benjamin.gaignard@...com
>> +Description:
>> + Reading returns counter current value.
> Assuming it counts every one this can definitely be in_count0_input (so processed)
> as it's in the 'base' units. Kind of hard not to be with a counter.
>
> Hohum. Just checked docs and this is documented as _raw.
> Oh well no real harm in doing that I guess so perhaps we just stay with that even
> if it's a little silly.
>
> Anyhow, no need to document stuff in here that is in the main docs
> sysfs-bus-iio
Ok I will remove it from stm32-timer documentation
>> +
>> +What: /sys/bus/iio/devices/iio:deviceX/in_count_count_direction_available
>> +KernelVersion: 4.12
>> +Contact: benjamin.gaignard@...com
>> +Description:
>> + Reading returns the list of possible counting directions which
>> + are:
>> + - "up" : counter is increasing.
>> + - "down": counter is decreasing.
> This is now generic enough we should probably move it into the main docs rather than
> repeating for each device.
>
> So cut this out of here and out of the 104_counter file and put it in
> sysfs-bus-iio.
>
> Note that for some you'll have to drop the bits in the 104-counter-quad-8 file that say
> if things are read only or not. The sysfs ABI docs don't need to say so that is fine.
Okay
>> +
>> +What: /sys/bus/iio/devices/iio:deviceX/in_count0_count_direction
>> +KernelVersion: 4.12
>> +Contact: benjamin.gaignard@...com
>> +Description:
>> + Reading returns the counting directions:
>> + - "up" : counter is increasing.
>> + - "down": counter is decreasing.
>> + Writing set the counting direction.
>> +
>> +What: /sys/bus/iio/devices/iio:deviceX/in_count_count_mode_available
>> +KernelVersion: 4.12
>> +Contact: benjamin.gaignard@...com
>> +Description:
> I still think this needs breaking up if we are going to have any hope of a generic interface.
>
>> + Reading returns the list of possible counting modes which are:
>> + - "internal_clock": Counter is clocked by the internal clock rising edges.
> This is about the feed clock - not a mode as such.
>
>> + - "encoder_1" : Counter counts up/down on channel 2 edge depending on channel 1 level.
>> + - "encoder_2" : Counter counts up/down on channel 1 edge depending on channel 2 level.
>> + - "encoder_3" : Counter counts up/down on channels 1 & 2 edge depending on channel 1 & 2 level.
> These combine the feed clock and the interpretation. To my mind, two different things.
>
> I kind of dislike the fact we can be either an internal clock or an encoder. seems that if you have an encoder
> wired it would be nuts to use the internal clock, but given we do this on various rigs at work to fake
> things when the encoder isn't moving I can't claim there is no use case ;)
>
>> + - "reset" : Rising edges on parent trigger reinitializes the counter value to preset value.
>> + - "gated" : Counter counts when the parent trigger input is high.
>> + Counter stops (but is not reset) as soon as the parent trigger becomes low.
>> + - "trigger" : Counter starts at a rising edge of the parent trigger (but it is not reset).
> These are gating of the feed clock
>
>> + - "trigger_rising_edges": Rising edges of the parent trigger are used as clock by the counter.
> This one is about the feed clock again.
>
> So we need at least 3 different things.
> 1. Feed clock selection.
> 2. Encoder interpretation selection - arguably we should have an explicit description of the encoder
> as a device in it's own right but I guess we can ignore that for now.
> 3. The parent trigger 'use'.
Here all is about how is clocked device counter, it could be by:
- the internal SoC clock rising edges
- the rising edges of some external pins (encoder, reset, gated, trigger)
- the rising edges of an internal signal which is represented by a trigger.
Without parent trigger I can already push the all except the last one.
Maybe doing like this is a better solution ?
>> +
>> + Encoder modes are used to automatically handle the counting direction of the internal counter.
>> + Those modes are typically used for high-accuracy rotor position sensing in electrical motors
>> + or for digital potentiometers. From the two outputs of a quadrature encoder sensor the timer
>> + extracts a clock on each and every active edge and adjusts the counting direction depending on
>> + the relative phase-shift between the two incomings signals. The timer counter thus directly
>> + holds the angular position of the motor.
>> +
>> + "trigger_rising_edges" mode is automatically set when a valid parent trigger is set.
>> +
>> +What: /sys/bus/iio/devices/iio:deviceX/in_count0_count_mode
>> +KernelVersion: 4.12
>> +Contact: benjamin.gaignard@...com
>> +Description:
>> + Reading returns the current counting mode.
>> +
>> +What: /sys/bus/iio/devices/iio:deviceX/in_count0_preset
>> +KernelVersion: 4.12
>> +Contact: benjamin.gaignard@...com
>> +Description:
>> + Reading returns the current preset value.
>> + Writing set the preset value.
>> + When counting up the counter start from 0 and fire an event when reach preset value.
>> + When counting down the counter start from preset value and fire event when reach 0.
> Fair enough, I hadn't thought if it like this, but makes sense.
>
>> diff --git a/drivers/iio/trigger/stm32-timer-trigger.c b/drivers/iio/trigger/stm32-timer-trigger.c
>> index 994b96d..04f5f05 100644
>> --- a/drivers/iio/trigger/stm32-timer-trigger.c
>> +++ b/drivers/iio/trigger/stm32-timer-trigger.c
>> @@ -15,6 +15,7 @@
>> #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] = {
>> @@ -32,12 +33,29 @@
>> { TIM12_TRGO, TIM12_CH1, TIM12_CH2,},
>> };
>>
>> +/* List the triggers accepted by each timer */
>> +static const void *valids_table[][MAX_VALIDS] = {
>> + { TIM5_TRGO, TIM2_TRGO, TIM3_TRGO, TIM4_TRGO,},
>> + { TIM1_TRGO, TIM8_TRGO, TIM3_TRGO, TIM4_TRGO,},
>> + { TIM1_TRGO, TIM2_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,},
>> + { }, /* timer 10 */
>> + { }, /* timer 11 */
>> + { 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,
>> @@ -180,8 +198,7 @@ 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);
>> + struct stm32_timer_trigger *priv = dev_get_drvdata(dev);
>> u32 cr2;
>>
>> regmap_read(priv->regmap, TIM_CR2, &cr2);
>> @@ -194,10 +211,10 @@ 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);
>> + struct stm32_timer_trigger *priv = dev_get_drvdata(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]))) {
>> @@ -225,6 +242,7 @@ static IIO_DEVICE_ATTR(master_mode, 0660,
>> &iio_dev_attr_sampling_frequency.dev_attr.attr,
>> &iio_dev_attr_master_mode.dev_attr.attr,
>> &iio_const_attr_master_mode_available.dev_attr.attr,
>> + &dev_attr_parent_trigger.attr,
>> NULL,
>> };
>>
>> @@ -237,8 +255,49 @@ static IIO_DEVICE_ATTR(master_mode, 0660,
>> NULL,
>> };
>>
>> +static int stm32_validate_trigger(struct iio_trigger *trig,
>> + struct iio_trigger *parent)
>> +{
>> + struct stm32_timer_trigger *priv = iio_trigger_get_drvdata(trig);
>> + const char * const *cur = priv->valids;
>> + unsigned int i = 0;
>> +
>> + if (!parent) {
>> + regmap_update_bits(priv->regmap, TIM_SMCR, TIM_SMCR_TS, 0);
>> + return 0;
>> + }
>> +
>> + if (!is_stm32_timer_trigger(parent))
>> + return -EINVAL;
>> +
>> + while (cur && *cur) {
>> + if (!strncmp(parent->name, *cur, strlen(parent->name))) {
>> + regmap_update_bits(priv->regmap,
>> + TIM_SMCR, TIM_SMCR_TS,
>> + i << TIM_SMCR_TS_SHIFT);
>> +
>> + /*
>> + * By default make parent trigger rising edges
>> + * use as clock for the counter
>> + */
>> + regmap_update_bits(priv->regmap, TIM_SMCR,
>> + TIM_SMCR_SMS, TIM_SMCR_SMS);
>> +
>> + /* Enable controller */
>> + regmap_update_bits(priv->regmap, TIM_CR1,
>> + TIM_CR1_CEN, TIM_CR1_CEN);
>> + return 0;
>> + }
>> + cur++;
>> + i++;
>> + }
>> +
>> + return -EINVAL;
>> +}
>> +
>> static const struct iio_trigger_ops timer_trigger_ops = {
>> .owner = THIS_MODULE,
>> + .validate_trigger = stm32_validate_trigger,
>> };
>>
>> static int stm32_setup_iio_triggers(struct stm32_timer_trigger *priv)
>> @@ -275,6 +334,185 @@ static int stm32_setup_iio_triggers(struct stm32_timer_trigger *priv)
>> return 0;
>> }
>>
>> +static int stm32_trigger_read_raw(struct iio_dev *indio_dev,
>> + struct iio_chan_spec const *chan,
>> + int *val, int *val2, long mask)
>> +{
>> + struct stm32_timer_trigger *priv = iio_priv(indio_dev);
>> +
>> + switch (mask) {
>> + case IIO_CHAN_INFO_RAW:
>> + {
>> + u32 cnt;
>> +
>> + regmap_read(priv->regmap, TIM_CNT, &cnt);
>> + *val = cnt;
>> +
>> + return IIO_VAL_INT;
>> + }
>> + }
>> +
>> + return -EINVAL;
>> +}
>> +
>> +static const struct iio_info stm32_trigger_info = {
>> + .driver_module = THIS_MODULE,
>> + .read_raw = stm32_trigger_read_raw,
>> +};
>> +
>> +static const char *const stm32_count_modes[] = {
>> + "internal_clock",
>> + "encoder_1",
>> + "encoder_2",
>> + "encoder_3",
>> + "reset",
>> + "gated",
>> + "trigger",
>> + "trigger_rising_edges"
>> +};
>> +
>> +static int stm32_set_count_mode(struct iio_dev *indio_dev,
>> + const struct iio_chan_spec *chan,
>> + unsigned int mode)
>> +{
>> + struct stm32_timer_trigger *priv = iio_priv(indio_dev);
>> +
>> + regmap_update_bits(priv->regmap, TIM_SMCR, TIM_SMCR_SMS, mode);
>> +
>> + return 0;
>> +}
>> +
>> +static int stm32_get_count_mode(struct iio_dev *indio_dev,
>> + const struct iio_chan_spec *chan)
>> +{
>> + struct stm32_timer_trigger *priv = iio_priv(indio_dev);
>> + u32 smcr;
>> +
>> + regmap_read(priv->regmap, TIM_SMCR, &smcr);
>> + smcr &= TIM_SMCR_SMS;
>> +
>> + return smcr;
>> +}
>> +
>> +static const struct iio_enum stm32_count_mode_enum = {
>> + .items = stm32_count_modes,
>> + .num_items = ARRAY_SIZE(stm32_count_modes),
>> + .set = stm32_set_count_mode,
>> + .get = stm32_get_count_mode
>> +};
>> +
>> +static const char *const stm32_count_direction_states[] = {
>> + "up",
>> + "down"
>> +};
>> +
>> +static int stm32_set_count_direction(struct iio_dev *indio_dev,
>> + const struct iio_chan_spec *chan,
>> + unsigned int mode)
>> +{
>> + struct stm32_timer_trigger *priv = iio_priv(indio_dev);
>> +
>> + regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_DIR, mode);
>> +
>> + return 0;
>> +}
>> +
>> +static int stm32_get_count_direction(struct iio_dev *indio_dev,
>> + const struct iio_chan_spec *chan)
>> +{
>> + struct stm32_timer_trigger *priv = iio_priv(indio_dev);
>> + u32 cr1;
>> +
>> + regmap_read(priv->regmap, TIM_CR1, &cr1);
>> +
>> + return (cr1 & TIM_CR1_DIR);
>> +}
>> +
>> +static const struct iio_enum stm32_count_direction_enum = {
>> + .items = stm32_count_direction_states,
>> + .num_items = ARRAY_SIZE(stm32_count_direction_states),
>> + .set = stm32_set_count_direction,
>> + .get = stm32_get_count_direction
>> +};
>> +
>> +static ssize_t stm32_count_get_preset(struct iio_dev *indio_dev,
>> + uintptr_t private,
>> + const struct iio_chan_spec *chan,
>> + char *buf)
>> +{
>> + struct stm32_timer_trigger *priv = iio_priv(indio_dev);
>> + u32 arr;
>> +
>> + regmap_read(priv->regmap, TIM_ARR, &arr);
>> +
>> + return snprintf(buf, PAGE_SIZE, "%u\n", arr);
>> +}
>> +
>> +static ssize_t stm32_count_set_preset(struct iio_dev *indio_dev,
>> + uintptr_t private,
>> + const struct iio_chan_spec *chan,
>> + const char *buf, size_t len)
>> +{
>> + struct stm32_timer_trigger *priv = iio_priv(indio_dev);
>> + unsigned int preset;
>> + int ret;
>> +
>> + ret = kstrtouint(buf, 0, &preset);
>> + if (ret)
>> + return ret;
>> +
>> + regmap_write(priv->regmap, TIM_ARR, preset);
>> + regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_ARPE, TIM_CR1_ARPE);
>> +
>> + return len;
>> +}
>> +
>> +static const struct iio_chan_spec_ext_info stm32_trigger_count_info[] = {
>> + {
>> + .name = "preset",
>> + .shared = IIO_SEPARATE,
>> + .read = stm32_count_get_preset,
>> + .write = stm32_count_set_preset
>> + },
>> + IIO_ENUM("count_direction", IIO_SEPARATE, &stm32_count_direction_enum),
>> + IIO_ENUM_AVAILABLE("count_direction", &stm32_count_direction_enum),
>> + IIO_ENUM("count_mode", IIO_SEPARATE, &stm32_count_mode_enum),
>> + IIO_ENUM_AVAILABLE("count_mode", &stm32_count_mode_enum),
>> + {}
>> +};
>> +
>> +static const struct iio_chan_spec stm32_trigger_channel = {
>> + .type = IIO_COUNT,
>> + .channel = 0,
>> + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
>> + .ext_info = stm32_trigger_count_info,
>> + .indexed = 1
>> +};
>> +
>> +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->num_channels = 1;
>> + indio_dev->channels = &stm32_trigger_channel;
>> + 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);
>> +}
>> +
>> /**
>> * is_stm32_timer_trigger
>> * @trig: trigger to be checked
>> @@ -299,10 +537,15 @@ static int stm32_timer_trigger_probe(struct platform_device *pdev)
>> if (of_property_read_u32(dev->of_node, "reg", &index))
>> return -EINVAL;
>>
>> - if (index >= ARRAY_SIZE(triggers_table))
>> + if (index >= ARRAY_SIZE(triggers_table)
>> + || index >= ARRAY_SIZE(valids_table))
>> return -EINVAL;
>>
>> - priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
>> + /* Create an IIO device only if we have triggers to be validated */
>> + if (*valids_table[index])
>> + priv = stm32_setup_iio_device(dev);
>> + else
>> + priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
>>
>> if (!priv)
>> return -ENOMEM;
>> @@ -312,6 +555,7 @@ static int stm32_timer_trigger_probe(struct platform_device *pdev)
>> 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)
>> diff --git a/include/linux/mfd/stm32-timers.h b/include/linux/mfd/stm32-timers.h
>> index d030004..4a0abbc 100644
>> --- a/include/linux/mfd/stm32-timers.h
>> +++ b/include/linux/mfd/stm32-timers.h
>> @@ -21,6 +21,7 @@
>> #define TIM_CCMR1 0x18 /* Capt/Comp 1 Mode Reg */
>> #define TIM_CCMR2 0x1C /* Capt/Comp 2 Mode Reg */
>> #define TIM_CCER 0x20 /* Capt/Comp Enable Reg */
>> +#define TIM_CNT 0x24 /* Counter */
>> #define TIM_PSC 0x28 /* Prescaler */
>> #define TIM_ARR 0x2c /* Auto-Reload Register */
>> #define TIM_CCR1 0x34 /* Capt/Comp Register 1 */
>> @@ -30,6 +31,7 @@
>> #define TIM_BDTR 0x44 /* Break and Dead-Time Reg */
>>
>> #define TIM_CR1_CEN BIT(0) /* Counter Enable */
>> +#define TIM_CR1_DIR BIT(4) /* Counter Direction */
>> #define TIM_CR1_ARPE BIT(7) /* Auto-reload Preload Ena */
>> #define TIM_CR2_MMS (BIT(4) | BIT(5) | BIT(6)) /* Master mode selection */
>> #define TIM_SMCR_SMS (BIT(0) | BIT(1) | BIT(2)) /* Slave mode selection */
>>
>
--
Benjamin Gaignard
Graphic Study Group
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