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Subject[PATCH 3/4] iio: dac: stm32: add support for trigger events
Date
STM32 DAC supports triggers to synchronize conversions. When trigger
occurs, data is transferred from DHR (data holding register) to DOR
(data output register) so output voltage is updated.
Both hardware and software triggers are supported.

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
---
drivers/iio/dac/Kconfig | 3 +
drivers/iio/dac/stm32-dac-core.h | 12 ++++
drivers/iio/dac/stm32-dac.c | 124 ++++++++++++++++++++++++++++++++++++++-
3 files changed, 136 insertions(+), 3 deletions(-)

diff --git a/drivers/iio/dac/Kconfig b/drivers/iio/dac/Kconfig
index 7198648..786c38b 100644
--- a/drivers/iio/dac/Kconfig
+++ b/drivers/iio/dac/Kconfig
@@ -278,6 +278,9 @@ config STM32_DAC
tristate "STMicroelectronics STM32 DAC"
depends on (ARCH_STM32 && OF) || COMPILE_TEST
depends on REGULATOR
+ select IIO_TRIGGERED_EVENT
+ select IIO_STM32_TIMER_TRIGGER
+ select MFD_STM32_TIMERS
select STM32_DAC_CORE
help
Say yes here to build support for STMicroelectronics STM32 Digital
diff --git a/drivers/iio/dac/stm32-dac-core.h b/drivers/iio/dac/stm32-dac-core.h
index d3099f7..3bf211c 100644
--- a/drivers/iio/dac/stm32-dac-core.h
+++ b/drivers/iio/dac/stm32-dac-core.h
@@ -26,6 +26,7 @@

/* STM32 DAC registers */
#define STM32_DAC_CR 0x00
+#define STM32_DAC_SWTRIGR 0x04
#define STM32_DAC_DHR12R1 0x08
#define STM32_DAC_DHR12R2 0x14
#define STM32_DAC_DOR1 0x2C
@@ -33,8 +34,19 @@

/* STM32_DAC_CR bit fields */
#define STM32_DAC_CR_EN1 BIT(0)
+#define STM32H7_DAC_CR_TEN1 BIT(1)
+#define STM32H7_DAC_CR_TSEL1_SHIFT 2
+#define STM32H7_DAC_CR_TSEL1 GENMASK(5, 2)
+#define STM32_DAC_CR_WAVE1 GENMASK(7, 6)
+#define STM32_DAC_CR_MAMP1 GENMASK(11, 8)
#define STM32H7_DAC_CR_HFSEL BIT(15)
#define STM32_DAC_CR_EN2 BIT(16)
+#define STM32_DAC_CR_WAVE2 GENMASK(23, 22)
+#define STM32_DAC_CR_MAMP2 GENMASK(27, 24)
+
+/* STM32_DAC_SWTRIGR bit fields */
+#define STM32_DAC_SWTRIGR_SWTRIG1 BIT(0)
+#define STM32_DAC_SWTRIGR_SWTRIG2 BIT(1)

/**
* struct stm32_dac_common - stm32 DAC driver common data (for all instances)
diff --git a/drivers/iio/dac/stm32-dac.c b/drivers/iio/dac/stm32-dac.c
index ee9711d..62e43e9 100644
--- a/drivers/iio/dac/stm32-dac.c
+++ b/drivers/iio/dac/stm32-dac.c
@@ -23,6 +23,10 @@
#include <linux/bitfield.h>
#include <linux/delay.h>
#include <linux/iio/iio.h>
+#include <linux/iio/timer/stm32-timer-trigger.h>
+#include <linux/iio/trigger.h>
+#include <linux/iio/trigger_consumer.h>
+#include <linux/iio/triggered_event.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/platform_device.h>
@@ -31,15 +35,112 @@

#define STM32_DAC_CHANNEL_1 1
#define STM32_DAC_CHANNEL_2 2
+/* channel2 shift */
+#define STM32_DAC_CHAN2_SHIFT 16

/**
* struct stm32_dac - private data of DAC driver
* @common: reference to DAC common data
+ * @swtrig: Using software trigger
*/
struct stm32_dac {
struct stm32_dac_common *common;
+ bool swtrig;
};

+/**
+ * struct stm32_dac_trig_info - DAC trigger info
+ * @name: name of the trigger, corresponding to its source
+ * @tsel: trigger selection, value to be configured in DAC_CR.TSELx
+ */
+struct stm32_dac_trig_info {
+ const char *name;
+ u32 tsel;
+};
+
+static const struct stm32_dac_trig_info stm32h7_dac_trinfo[] = {
+ { "swtrig", 0 },
+ { TIM1_TRGO, 1 },
+ { TIM2_TRGO, 2 },
+ { TIM4_TRGO, 3 },
+ { TIM5_TRGO, 4 },
+ { TIM6_TRGO, 5 },
+ { TIM7_TRGO, 6 },
+ { TIM8_TRGO, 7 },
+ {},
+};
+
+static irqreturn_t stm32_dac_trigger_handler(int irq, void *p)
+{
+ struct iio_poll_func *pf = p;
+ struct iio_dev *indio_dev = pf->indio_dev;
+ struct stm32_dac *dac = iio_priv(indio_dev);
+ int channel = indio_dev->channels[0].channel;
+
+ /* Using software trigger? Then, trigger it now */
+ if (dac->swtrig) {
+ u32 swtrig;
+
+ if (channel == STM32_DAC_CHANNEL_1)
+ swtrig = STM32_DAC_SWTRIGR_SWTRIG1;
+ else
+ swtrig = STM32_DAC_SWTRIGR_SWTRIG2;
+ regmap_update_bits(dac->common->regmap, STM32_DAC_SWTRIGR,
+ swtrig, swtrig);
+ }
+
+ iio_trigger_notify_done(indio_dev->trig);
+
+ return IRQ_HANDLED;
+}
+
+static unsigned int stm32_dac_get_trig_tsel(struct stm32_dac *dac,
+ struct iio_trigger *trig)
+{
+ unsigned int i;
+
+ /* skip 1st trigger that should be swtrig */
+ for (i = 1; stm32h7_dac_trinfo[i].name; i++) {
+ /*
+ * Checking both stm32 timer trigger type and trig name
+ * should be safe against arbitrary trigger names.
+ */
+ if (is_stm32_timer_trigger(trig) &&
+ !strcmp(stm32h7_dac_trinfo[i].name, trig->name)) {
+ return stm32h7_dac_trinfo[i].tsel;
+ }
+ }
+
+ /* When no trigger has been found, default to software trigger */
+ dac->swtrig = true;
+
+ return stm32h7_dac_trinfo[0].tsel;
+}
+
+static int stm32_dac_set_trig(struct stm32_dac *dac, struct iio_trigger *trig,
+ int channel)
+{
+ struct iio_dev *indio_dev = iio_priv_to_dev(dac);
+ u32 shift = channel == STM32_DAC_CHANNEL_1 ? 0 : STM32_DAC_CHAN2_SHIFT;
+ u32 val = 0, tsel;
+ u32 msk = (STM32H7_DAC_CR_TEN1 | STM32H7_DAC_CR_TSEL1) << shift;
+
+ dac->swtrig = false;
+ if (trig) {
+ /* select & enable trigger (tsel / ten) */
+ tsel = stm32_dac_get_trig_tsel(dac, trig);
+ val = tsel << STM32H7_DAC_CR_TSEL1_SHIFT;
+ val = (val | STM32H7_DAC_CR_TEN1) << shift;
+ }
+
+ if (trig)
+ dev_dbg(&indio_dev->dev, "enable trigger: %s\n", trig->name);
+ else
+ dev_dbg(&indio_dev->dev, "disable trigger\n");
+
+ return regmap_update_bits(dac->common->regmap, STM32_DAC_CR, msk, val);
+}
+
static int stm32_dac_is_enabled(struct stm32_dac *dac, int channel)
{
u32 en, val;
@@ -63,9 +164,16 @@ static int stm32_dac_enable(struct iio_dev *indio_dev, int channel)
STM32_DAC_CR_EN1 : STM32_DAC_CR_EN2;
int ret;

+ ret = stm32_dac_set_trig(dac, indio_dev->trig, channel);
+ if (ret < 0) {
+ dev_err(&indio_dev->dev, "Trigger setup failed\n");
+ return ret;
+ }
+
ret = regmap_update_bits(dac->common->regmap, STM32_DAC_CR, en, en);
if (ret < 0) {
dev_err(&indio_dev->dev, "Enable failed\n");
+ stm32_dac_set_trig(dac, NULL, channel);
return ret;
}

@@ -88,10 +196,12 @@ static int stm32_dac_disable(struct iio_dev *indio_dev, int channel)
int ret;

ret = regmap_update_bits(dac->common->regmap, STM32_DAC_CR, en, 0);
- if (ret)
+ if (ret) {
dev_err(&indio_dev->dev, "Disable failed\n");
+ return ret;
+ }

- return ret;
+ return stm32_dac_set_trig(dac, NULL, channel);
}

static int stm32_dac_get_value(struct stm32_dac *dac, int channel, int *val)
@@ -258,10 +368,17 @@ static int stm32_dac_probe(struct platform_device *pdev)
if (ret < 0)
return ret;

- ret = iio_device_register(indio_dev);
+ ret = iio_triggered_event_setup(indio_dev, NULL,
+ stm32_dac_trigger_handler);
if (ret)
return ret;

+ ret = iio_device_register(indio_dev);
+ if (ret) {
+ iio_triggered_event_cleanup(indio_dev);
+ return ret;
+ }
+
return 0;
}

@@ -269,6 +386,7 @@ static int stm32_dac_remove(struct platform_device *pdev)
{
struct iio_dev *indio_dev = platform_get_drvdata(pdev);

+ iio_triggered_event_cleanup(indio_dev);
iio_device_unregister(indio_dev);

return 0;
--
1.9.1
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