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Date: Thu, 16 Feb 2017 15:23:03 +0100
From: Benjamin Gaignard <benjamin.gaignard@...aro.org>
To: linux-kernel@...r.kernel.org, jic23@...nel.org,
linux-iio@...r.kernel.org, knaack.h@....de, lars@...afoo.de,
pmeerw@...erw.net
Cc: fabrice.gasnier@...com, linaro-kernel@...ts.linaro.org,
benjamin.gaignard@...aro.org,
Benjamin Gaignard <benjamin.gaignard@...com>
Subject: [PATCH v2 2/2] iio: stm32 trigger: Implement parent trigger feature
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.
Because the hardware have 8 different ways to use parent levels and
edges, this patch introduce "slave_mode" sysfs attribute for stm32
triggers. Modes usages are described in sysfs-bus-iio-timer-stm32
Signed-off-by: Benjamin Gaignard <benjamin.gaignard@...com>
version 2:
- use dev_attr_parent_trigger
- improve slave modes documentation
---
.../ABI/testing/sysfs-bus-iio-timer-stm32 | 43 +++++++++
drivers/iio/trigger/stm32-timer-trigger.c | 105 +++++++++++++++++++++
2 files changed, 148 insertions(+)
diff --git a/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32 b/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32
index 6534a60..7d667f9 100644
--- a/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32
+++ b/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32
@@ -27,3 +27,46 @@ 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/triggerX/slave_mode_available
+KernelVersion: 4.12
+Contact: benjamin.gaignard@...com
+Description:
+ Reading returns the list possible slave modes which are:
+ - "disabled" : Parent trigger levels or edges have do not impact on trigger.
+ Trigger is clocked by the internal clock.
+ This is the default mode.
+ - "encoder_1" : Trigger internal counter counts up/down on channel 2 edge depending on channel 1 level.
+ - "encoder_2" : Trigger internal counter counts up/down on channel 1 edge depending on channel 2 level.
+ - "encoder_3" : Trigger internal counter counts up/down on channels 1 & 2 edge
+ depending on channel 1 & 2 level.
+ - "reset" : Rising edge on parent trigger reinitializes the trigger and generates
+ an update of auto-reload, prescaler and repetition counter registers.
+ - "gated" : The trigger is enabled when the parent trigger input is high.
+ The trigger stops (but is not reset) as soon as the parent trigger becomes low.
+ - "trigger" : The trigger starts at a rising edge of the parent trigger (but it is not reset).
+ - "external_clock": Rising edges of the parent trigger clock the trigger.
+
+ 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 or the potentionmeter.
+
+ For "reset", "gated" and "trigger" modes the trigger will fire N+1 times when internal counter
+ will reach the value of auto-reload register. N is defined by the value of repetition counter.
+ Those modes could allow parent trigger to control when sampling frequency of the current trigger
+ start or stop.
+ Since PWM and trigger features are mixed in the same hardware block those 3 modes could be used
+ to synchronize PWMs start while PWM sysfs API is used to set period and duty cycle.
+
+ In "external clock" mode parent trigger can control the current trigger clock (and so the sampling
+ frequency) for example to correct jittering.
+
+What: /sys/bus/iio/devices/triggerX/slave_mode
+KernelVersion: 4.12
+Contact: benjamin.gaignard@...com
+Description:
+ Reading returns the current slave mode.
+ Writing set the slave mode
diff --git a/drivers/iio/trigger/stm32-timer-trigger.c b/drivers/iio/trigger/stm32-timer-trigger.c
index 994b96d..a4f1061 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, 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,},
+ { }, /* 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,
@@ -221,10 +239,66 @@ static IIO_DEVICE_ATTR(master_mode, 0660,
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_trigger_attrs[] = {
&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,
+ &iio_dev_attr_slave_mode.dev_attr.attr,
+ &iio_const_attr_slave_mode_available.dev_attr.attr,
+ &dev_attr_parent_trigger.attr,
NULL,
};
@@ -237,8 +311,38 @@ 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);
+ 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)
@@ -312,6 +416,7 @@ 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)
--
1.9.1
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