Re: [PATCH v2 1/2] iio: stm32 trigger: Add quadrature encoder device

From: Michael Welling
Date: Sat Mar 25 2017 - 19:23:46 EST

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On Sat, Mar 25, 2017 at 06:26:05PM +0000, Jonathan Cameron wrote:
> On 24/03/17 14:00, Benjamin Gaignard wrote:
> > One of the features of STM32 trigger hardware block is a quadrature
> > encoder that can counts up/down depending of the levels and edges
> > of the selected external pins.
> >
> > This patch allow to read/write the counter, get it direction,
> > set/get quadrature modes and get scale factor.
> >
> > When counting up preset value is the limit of the counter.
> > When counting down the counter start from preset value down to 0.
> > This preset value could be set/get by using
> > /sys/bus/iio/devices/iio:deviceX/in_count0_preset attribute.
> >
> > Signed-off-by: Benjamin Gaignard <benjamin.gaignard@xxxxxx>
> A few little nitpicks.
>
> Otherwise I like this. Would love William to give another review
> though if he has time.
>
> I've tacked Michael Welling on the cc list as well as he has offered
> to help the beaglebone lot upstream some drivers, including the
> eqep quadrature encoder drivers - so he can poke the right people
> to get some review of the ABI from their point of view as well.
>

BTW here is the out of tree module that will be converted to IIO eventually.
https://github.com/Teknoman117/beaglebot/tree/master/encoders

There are probably more requirements to encapsulate all of the features of the eQEP.

> Thanks
>
> Jonathan
> > ---
> > .../ABI/testing/sysfs-bus-iio-timer-stm32 | 32 +++
> > drivers/iio/trigger/stm32-timer-trigger.c | 244 ++++++++++++++++++++-
> > include/linux/mfd/stm32-timers.h | 2 +
> > 3 files changed, 272 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..fbdee4f 100644
> > --- a/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32
> > +++ b/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32
> > @@ -27,3 +27,35 @@ 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_preset
> > +KernelVersion: 4.12
> > +Contact: benjamin.gaignard@xxxxxx
> > +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.
> We'll want to generalize that description at some point as it's most often used as a place to reset
> too on an event (homing switch or similar)
> > +
> > +What: /sys/bus/iio/devices/iio:deviceX/in_count_quadrature_mode_available
> > +KernelVersion: 4.12
> > +Contact: benjamin.gaignard@xxxxxx
> > +Description:
> > + Reading returns the list possible quadrature modes.
> > +
> > +What: /sys/bus/iio/devices/iio:deviceX/in_count0_quadrature_mode
> > +KernelVersion: 4.12
> > +Contact: benjamin.gaignard@xxxxxx
> > +Description:
> > + Configure the device counter quadrature modes:
> > + channel_A:
> > + Encoder A input severs as the count input and B as
> > + the UP/DOWN direction control input.
> > +
> > + channel_B:
> > + Encoder B input severs as the count input and A as
> > + the UP/DOWN direction control input.
> > +
> > + quadrature:
> > + Encoder A and B inputs are mixed to get direction
> > + and count with a scale of 0.25.
> Whilst the quadrature mode is always with that scale on this device, we should
> as discussed be explicitly providing access to the scale so that we can
> cope with different scales on different devices. As such the docs here
> shouldn't mention it.
>
> I'm keen to get these docs straight into sysfs-bus-iio or perhaps
> sysfs-bus-iio-encoder-counter asap so good to write them with that at the
> front of your mind.
>
> > diff --git a/drivers/iio/trigger/stm32-timer-trigger.c b/drivers/iio/trigger/stm32-timer-trigger.c
> > index 994b96d..48d2bf9 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);
> > @@ -194,8 +211,7 @@ 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++) {
> > @@ -275,6 +291,216 @@ 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)
> I really don't like the naming as trigger_read_raw. Lets just
> call it counter_read_raw and then it 'feels' much nicer ;)
>
> The driver is becoming a two part one with a trigger and a counter
> driver (and links between them). Lets let the naming reflect that.
> > +{
> > + 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;
> > + }
> > + case IIO_CHAN_INFO_SCALE:
> > + {
> > + u32 smcr;
> > +
> > + regmap_read(priv->regmap, TIM_SMCR, &smcr);
> > + smcr &= TIM_SMCR_SMS;
> > +
> > + /* return scale only if quadrature mode is selected */
> > + if (smcr != 3)
> > + return -EINVAL;
> Why not return a scale of unity rather than an error? (which will confuse
> users).
> > +
> > + /* fixed scale */
> > + *val = 1;
> > + *val2 = 2;
> > + return IIO_VAL_FRACTIONAL_LOG2;
> > + }
> > + }
> > +
> > + return -EINVAL;
> > +}
> > +
> > +static int stm32_trigger_write_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:
> > + regmap_write(priv->regmap, TIM_CNT, val);
> > +
> > + return IIO_VAL_INT;
> > + case IIO_CHAN_INFO_SCALE:
> > + /* fixed scale */
> > + return -EINVAL;
> > + }
> > +
> > + return -EINVAL;
> > +}
> > +
> > +static const struct iio_info stm32_trigger_info = {
> > + .driver_module = THIS_MODULE,
> > + .read_raw = stm32_trigger_read_raw,
> > + .write_raw = stm32_trigger_write_raw
> > +};
> > +
> > +static const char *const stm32_quadrature_modes[] = {
> > + "channel_A",
> > + "channel_B",
> > + "quadrature",
> > +};
> > +
> > +static int stm32_set_quadrature_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 + 1);
> > +
> > + return 0;
> > +}
> > +
> > +static int stm32_get_quadrature_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 - 1;
> > +}
> > +
> > +static const struct iio_enum stm32_quadrature_mode_enum = {
> > + .items = stm32_quadrature_modes,
> > + .num_items = ARRAY_SIZE(stm32_quadrature_modes),
> > + .set = stm32_set_quadrature_mode,
> > + .get = stm32_get_quadrature_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("quadrature_mode", IIO_SEPARATE, &stm32_quadrature_mode_enum),
> > + IIO_ENUM_AVAILABLE("quadrature_mode", &stm32_quadrature_mode_enum),
> > + {}
> > +};
> > +
> > +static const struct iio_chan_spec stm32_trigger_channel = {
> > + .type = IIO_COUNT,
> > + .channel = 0,
> > + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
> > + .ext_info = stm32_trigger_count_info,
> > + .indexed = 1
> > +};
> > +
> > +static struct stm32_timer_trigger *stm32_setup_iio_device(struct device *dev)
> That wins the slightly overly generic name! There are several other
> stm32 iio devices already. setup_counter_device maybe?
> > +{
> > + 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 +525,15 @@ 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 +543,7 @@ 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 */
> >
>

Next message: Guillaume Brogi: "[PATCH] Convert __le16 to cpu before casting to u32"
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In reply to: Michael Welling: "Re: [PATCH v2 1/2] iio: stm32 trigger: Add quadrature encoder device"
Next in thread: Benjamin Gaignard: "[PATCH v2 2/2] iio: stm32 trigger: Add counter enable modes"
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