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Date: Mon, 27 Mar 2017 16:14:25 +0200
From: Benjamin Gaignard <benjamin.gaignard@...aro.org>
To: William Breathitt Gray <vilhelm.gray@...il.com>
Cc: Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Jonathan Cameron <jic23@...nel.org>, linux-iio@...r.kernel.org,
Hartmut Knaack <knaack.h@....de>,
Lars-Peter Clausen <lars@...afoo.de>,
Peter Meerwald-Stadler <pmeerw@...erw.net>, mwelling@...e.org,
Fabrice Gasnier <fabrice.gasnier@...com>,
Linaro Kernel Mailman List <linaro-kernel@...ts.linaro.org>,
Benjamin Gaignard <benjamin.gaignard@...com>
Subject: Re: [PATCH v3 1/2] iio: stm32 trigger: Add quadrature encoder device
2017-03-27 15:47 GMT+02:00 William Breathitt Gray <vilhelm.gray@...il.com>:
> On Mon, Mar 27, 2017 at 11:43:23AM +0200, 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@...com>
>
> Hi Benjamin,
>
> This is pretty close to the ABI I had in mind. I'm a bit confused about
> how to select some of functionality we discussed in the previous version
> so I'll write those comments inline. Overall nice work! :)
>
>>
>>version 3:
>>- fix typo in documentation
>>- change some functions names
>>---
>> .../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..bf795ad 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@...com
>>+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.
>
> In one of the previous versions we discussed a "reset" mode of operation
> where the counter would be reset to the preset value on the rising edge
> of pin 1. How would a user select this mode of operation using this ABI
> (I assume the preset value would be the same value as in the
> in_count0_preset attribute).
>
> Also, would this "reset" mode be limited to count just the internal
> clock, or may an external pin alternatively serve as a counter source?
In reset mode counter is clocked by the internal clock
Reset can only by drive by a rising edge of an internal signal
(represented by an IIO trigger).
>
>>+
>>+What: /sys/bus/iio/devices/iio:deviceX/in_count_quadrature_mode_available
>>+KernelVersion: 4.12
>>+Contact: benjamin.gaignard@...com
>>+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@...com
>>+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.
>
> If I want to select the internal clock as the counter source, how would
> I do so? Should there be an "internal_clock" mode available in the
> quadrature_mode attribute?
To use internal clock as counter source you must select one of the modes
in in_count0_enable_mode attribute (patch 2/2)
Counter could be drived by 3 "sources": internal clock, encoder input
and internal signal
I have in mind to keep this split in 3 attributes:enable_mode,
quadrature_mode and a futur
trigger_mode.
>
> Sincerely,
>
> William Breathitt Gray
>
>>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 */
>>--
>>1.9.1
>>
--
Benjamin Gaignard
Graphic Study Group
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