[PATCH v2 5/5] iio: dac: stm32: add support for waveform generator

From: Fabrice Gasnier
Date: Thu Apr 06 2017 - 12:14:25 EST

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STM32 DAC has built-in noise or triangle waveform generator.
- "wavetype" extended attribute selects noise or triangle.
- "amplitude" extended attribute selects amplitude for waveform generator

A DC offset can be added to waveform generator output. This can be done
using out_voltage[1/2]_offset

Waveform generator requires a trigger to be configured, to increment /
decrement internal counter in case of triangle generator. Noise
generator is a bit different, but also requires a trigger to generate
samples.

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@xxxxxx>
---
Changes in v2:
- use _offset parameter to add DC offset to waveform generator
- Rework ABI to better fit existing DDS ABI: use out_voltageY_wavetype,
out_voltage_wavetype_available, out_voltageY_amplitude,
out_voltage_amplitude_available
- Better explain trigger usage in case of waveform generator.
---
Documentation/ABI/testing/sysfs-bus-iio-dac-stm32 | 16 +++
drivers/iio/dac/stm32-dac-core.h | 4 +
drivers/iio/dac/stm32-dac.c | 158 +++++++++++++++++++++-
3 files changed, 177 insertions(+), 1 deletion(-)
create mode 100644 Documentation/ABI/testing/sysfs-bus-iio-dac-stm32

diff --git a/Documentation/ABI/testing/sysfs-bus-iio-dac-stm32 b/Documentation/ABI/testing/sysfs-bus-iio-dac-stm32
new file mode 100644
index 0000000..8f1fa009
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-bus-iio-dac-stm32
@@ -0,0 +1,16 @@
+What: /sys/bus/iio/devices/iio:deviceX/out_voltageY_wavetype
+What: /sys/bus/iio/devices/iio:deviceX/out_voltage_wavetype_available
+KernelVersion: 4.12
+Contact: fabrice.gasnier@xxxxxx
+Description:
+ List and/or select waveform generation provided by STM32 DAC:
+ - "flat": waveform generator disabled (default)
+ - "noise": select noise waveform
+ - "triangle": select triangle waveform
+
+What: /sys/bus/iio/devices/iio:deviceX/out_voltageY_amplitude
+What: /sys/bus/iio/devices/iio:deviceX/out_voltage_amplitude_available
+KernelVersion: 4.12
+Contact: fabrice.gasnier@xxxxxx
+Description:
+ List and/or select amplitude used for waveform generator
diff --git a/drivers/iio/dac/stm32-dac-core.h b/drivers/iio/dac/stm32-dac-core.h
index e51a468..0f02975 100644
--- a/drivers/iio/dac/stm32-dac-core.h
+++ b/drivers/iio/dac/stm32-dac-core.h
@@ -37,8 +37,12 @@
#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)
diff --git a/drivers/iio/dac/stm32-dac.c b/drivers/iio/dac/stm32-dac.c
index a7a078e..2ed75db 100644
--- a/drivers/iio/dac/stm32-dac.c
+++ b/drivers/iio/dac/stm32-dac.c
@@ -42,10 +42,12 @@
/**
* struct stm32_dac - private data of DAC driver
* @common: reference to DAC common data
+ * @wavetype: waveform generator
* @swtrig: Using software trigger
*/
struct stm32_dac {
struct stm32_dac_common *common;
+ u32 wavetype;
bool swtrig;
};

@@ -222,6 +224,29 @@ static int stm32_dac_set_value(struct stm32_dac *dac, int channel, int val)
return ret;
}

+static int stm32_dac_get_offset(struct stm32_dac *dac, int channel, int *val)
+{
+ int ret;
+
+ /* Offset is only relevant in waveform generation mode. */
+ if (!dac->wavetype) {
+ *val = 0;
+ return IIO_VAL_INT;
+ }
+
+ /*
+ * In waveform generation mode, DC offset in DHR is added to waveform
+ * generator output, then stored to DOR (data output register).
+ * Read offset from DHR.
+ */
+ if (STM32_DAC_IS_CHAN_1(channel))
+ ret = regmap_read(dac->common->regmap, STM32_DAC_DHR12R1, val);
+ else
+ ret = regmap_read(dac->common->regmap, STM32_DAC_DHR12R2, val);
+
+ return ret ? ret : IIO_VAL_INT;
+}
+
static int stm32_dac_read_raw(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan,
int *val, int *val2, long mask)
@@ -231,6 +256,8 @@ static int stm32_dac_read_raw(struct iio_dev *indio_dev,
switch (mask) {
case IIO_CHAN_INFO_RAW:
return stm32_dac_get_value(dac, chan->channel, val);
+ case IIO_CHAN_INFO_OFFSET:
+ return stm32_dac_get_offset(dac, chan->channel, val);
case IIO_CHAN_INFO_SCALE:
*val = dac->common->vref_mv;
*val2 = chan->scan_type.realbits;
@@ -247,8 +274,16 @@ static int stm32_dac_write_raw(struct iio_dev *indio_dev,
struct stm32_dac *dac = iio_priv(indio_dev);

switch (mask) {
+ case IIO_CHAN_INFO_OFFSET:
+ /* Offset only makes sense in waveform generation mode */
+ if (dac->wavetype)
+ return stm32_dac_set_value(dac, chan->channel, val);
+ return -EBUSY;
case IIO_CHAN_INFO_RAW:
- return stm32_dac_set_value(dac, chan->channel, val);
+ if (!dac->wavetype)
+ return stm32_dac_set_value(dac, chan->channel, val);
+ /* raw value is read only in waveform generation mode */
+ return -EBUSY;
default:
return -EINVAL;
}
@@ -334,6 +369,122 @@ static ssize_t stm32_dac_write_powerdown(struct iio_dev *indio_dev,
.set = stm32_dac_set_powerdown_mode,
};

+/* waveform generator wave selection */
+static const char * const stm32_dac_wavetype_desc[] = {
+ "flat",
+ "noise",
+ "triangle",
+};
+
+static int stm32_dac_set_wavetype(struct iio_dev *indio_dev,
+ const struct iio_chan_spec *chan,
+ unsigned int wavetype)
+{
+ struct stm32_dac *dac = iio_priv(indio_dev);
+ u32 mask, val;
+ int ret;
+
+ /*
+ * Waveform generator requires a trigger to be configured, to increment
+ * or decrement internal counter in case of triangle generator. Noise
+ * generator is a bit different, but also requires a trigger to
+ * generate samples.
+ */
+ if (wavetype && !indio_dev->trig)
+ dev_dbg(&indio_dev->dev, "Wavegen requires a trigger\n");
+
+ if (STM32_DAC_IS_CHAN_1(chan->channel)) {
+ val = FIELD_PREP(STM32_DAC_CR_WAVE1, wavetype);
+ mask = STM32_DAC_CR_WAVE1;
+ } else {
+ val = FIELD_PREP(STM32_DAC_CR_WAVE2, wavetype);
+ mask = STM32_DAC_CR_WAVE2;
+ }
+
+ ret = regmap_update_bits(dac->common->regmap, STM32_DAC_CR, mask, val);
+ if (ret)
+ return ret;
+ dac->wavetype = wavetype;
+
+ return 0;
+}
+
+static int stm32_dac_get_wavetype(struct iio_dev *indio_dev,
+ const struct iio_chan_spec *chan)
+{
+ struct stm32_dac *dac = iio_priv(indio_dev);
+ u32 val;
+ int ret;
+
+ ret = regmap_read(dac->common->regmap, STM32_DAC_CR, &val);
+ if (ret < 0)
+ return ret;
+
+ if (STM32_DAC_IS_CHAN_1(chan->channel))
+ return FIELD_GET(STM32_DAC_CR_WAVE1, val);
+ else
+ return FIELD_GET(STM32_DAC_CR_WAVE2, val);
+}
+
+static const struct iio_enum stm32_dac_wavetype_enum = {
+ .items = stm32_dac_wavetype_desc,
+ .num_items = ARRAY_SIZE(stm32_dac_wavetype_desc),
+ .get = stm32_dac_get_wavetype,
+ .set = stm32_dac_set_wavetype,
+};
+
+/*
+ * waveform generator mamp selection: mask/amplitude
+ * - noise: LFSR mask (linear feedback shift register, umasks bit 0, [1:0]...)
+ * - triangle: amplitude (equal to 1, 3, 5, 7... 4095)
+ */
+static const char * const stm32_dac_amplitude_desc[] = {
+ "1", "3", "7", "15", "31", "63", "127", "255", "511", "1023", "2047",
+ "4095",
+};
+
+static int stm32_dac_set_amplitude(struct iio_dev *indio_dev,
+ const struct iio_chan_spec *chan,
+ unsigned int amplitude)
+{
+ struct stm32_dac *dac = iio_priv(indio_dev);
+ u32 mask, val;
+
+ if (STM32_DAC_IS_CHAN_1(chan->channel)) {
+ val = FIELD_PREP(STM32_DAC_CR_MAMP1, amplitude);
+ mask = STM32_DAC_CR_MAMP1;
+ } else {
+ val = FIELD_PREP(STM32_DAC_CR_MAMP2, amplitude);
+ mask = STM32_DAC_CR_MAMP2;
+ }
+
+ return regmap_update_bits(dac->common->regmap, STM32_DAC_CR, mask, val);
+}
+
+static int stm32_dac_get_amplitude(struct iio_dev *indio_dev,
+ const struct iio_chan_spec *chan)
+{
+ struct stm32_dac *dac = iio_priv(indio_dev);
+ u32 val;
+ int ret;
+
+ ret = regmap_read(dac->common->regmap, STM32_DAC_CR, &val);
+ if (ret < 0)
+ return ret;
+
+ if (STM32_DAC_IS_CHAN_1(chan->channel))
+ return FIELD_GET(STM32_DAC_CR_MAMP1, val);
+ else
+ return FIELD_GET(STM32_DAC_CR_MAMP2, val);
+}
+
+static const struct iio_enum stm32_dac_amplitude_enum = {
+ .items = stm32_dac_amplitude_desc,
+ .num_items = ARRAY_SIZE(stm32_dac_amplitude_desc),
+ .get = stm32_dac_get_amplitude,
+ .set = stm32_dac_set_amplitude,
+};
+
static const struct iio_chan_spec_ext_info stm32_dac_ext_info[] = {
{
.name = "powerdown",
@@ -343,6 +494,10 @@ static ssize_t stm32_dac_write_powerdown(struct iio_dev *indio_dev,
},
IIO_ENUM("powerdown_mode", IIO_SEPARATE, &stm32_dac_powerdown_mode_en),
IIO_ENUM_AVAILABLE("powerdown_mode", &stm32_dac_powerdown_mode_en),
+ IIO_ENUM("wavetype", IIO_SEPARATE, &stm32_dac_wavetype_enum),
+ IIO_ENUM_AVAILABLE("wavetype", &stm32_dac_wavetype_enum),
+ IIO_ENUM("amplitude", IIO_SEPARATE, &stm32_dac_amplitude_enum),
+ IIO_ENUM_AVAILABLE("amplitude", &stm32_dac_amplitude_enum),
{},
};

@@ -352,6 +507,7 @@ static ssize_t stm32_dac_write_powerdown(struct iio_dev *indio_dev,
.output = 1, \
.channel = chan, \
.info_mask_separate = \
+ BIT(IIO_CHAN_INFO_OFFSET) | \
BIT(IIO_CHAN_INFO_RAW) | \
BIT(IIO_CHAN_INFO_SCALE), \
/* scan_index is always 0 as num_channels is 1 */ \
--
1.9.1

Next message: kathcullen: "Hallo,"
Previous message: Fabrice Gasnier: "[PATCH v2 3/5] iio: trigger: add set_trigger callback to notify device"
In reply to: Fabrice Gasnier: "[PATCH v2 3/5] iio: trigger: add set_trigger callback to notify device"
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