Re: [PATCH v4 1/2] iio: stm32 trigger: Add quadrature encoder device

From: Jonathan Cameron
Date: Sat Apr 08 2017 - 13:29:49 EST

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On 04/04/17 08:47, 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>
>
> ---
> version 4:
> - fix indentation in documentation
Would have preferred that initial fixes as a separate patch, but
doesn't matter that much.

Applied to the togreg branch of iio.git. If William for example
wants to give a reviewed-by or similar then there is time whilst
this is still in testing going through the autobuilders.

Jonathan
>
> version 3:
> - fix typo in documentation
> - change some functions names
>
> .../ABI/testing/sysfs-bus-iio-timer-stm32 | 46 +++-
> drivers/iio/trigger/stm32-timer-trigger.c | 244 ++++++++++++++++++++-
> include/linux/mfd/stm32-timers.h | 2 +
> 3 files changed, 282 insertions(+), 10 deletions(-)
>
> diff --git a/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32 b/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32
> index 6534a60..a55ad44 100644
> --- a/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32
> +++ b/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32
> @@ -3,11 +3,15 @@ KernelVersion: 4.11
> 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.
> + - "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.
> + 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.
> @@ -27,3 +31,37 @@ 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 sets the preset value.
> + When counting up the counter starts from 0 and fires an
> + event when reach preset value.
> + When counting down the counter start from preset value
> + and fire event when reach 0.
> +
> +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 servers as the count input and B as
> + the UP/DOWN direction control input.
> +
> + channel_B:
> + Encoder B input serves 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.
> diff --git a/drivers/iio/trigger/stm32-timer-trigger.c b/drivers/iio/trigger/stm32-timer-trigger.c
> index 994b96d..7db904c 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_counter_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;
> + }
> + case IIO_CHAN_INFO_SCALE:
> + {
> + u32 smcr;
> +
> + regmap_read(priv->regmap, TIM_SMCR, &smcr);
> + smcr &= TIM_SMCR_SMS;
> +
> + *val = 1;
> + *val2 = 0;
> +
> + /* in quadrature case scale = 0.25 */
> + if (smcr == 3)
> + *val2 = 2;
> +
> + return IIO_VAL_FRACTIONAL_LOG2;
> + }
> + }
> +
> + return -EINVAL;
> +}
> +
> +static int stm32_counter_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_counter_read_raw,
> + .write_raw = stm32_counter_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_counter_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 +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_counter_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 */
>

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