STM32 DAC has built-in noise or triangle waveform generator. Waveform generator requires trigger to be configured. - "wave" extended attribute selects noise or triangle. - "mamp" extended attribute selects either LFSR (linear feedback shift register) mask for noise waveform, OR triangle amplitude.
Signed-off-by: Fabrice Gasnier <[email protected]> --- Documentation/ABI/testing/sysfs-bus-iio-dac-stm32 | 32 ++++++ drivers/iio/dac/stm32-dac.c | 124 ++++++++++++++++++++++ 2 files changed, 156 insertions(+) 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..c2432e1 --- /dev/null +++ b/Documentation/ABI/testing/sysfs-bus-iio-dac-stm32 @@ -0,0 +1,32 @@ +What: /sys/bus/iio/devices/iio:deviceX/wave +What: /sys/bus/iio/devices/iio:deviceX/wave_available +KernelVersion: 4.12 +Contact: [email protected] +Description: + List and/or select waveform generation provided by STM32 DAC: + - "none": (default) means normal DAC operations + - "noise": select noise waveform + - "triangle": select triangle waveform + Note: when waveform generator is used, writing _raw sysfs entry + adds a DC offset to generated waveform. Reading it reports + current output value. + +What: /sys/bus/iio/devices/iio:deviceX/mamp +What: /sys/bus/iio/devices/iio:deviceX/mamp_available +KernelVersion: 4.12 +Contact: [email protected] +Description: + List and select mask/amplitude used for noise/triangle waveform + generator, which are: + - "0": unmask bit 0 of LFSR / triangle amplitude equal to 1 + - "1": unmask bit [1:0] of LFSR / triangle amplitude equal to 3 + - "2": unmask bit [2:0] of LFSR / triangle amplitude equal to 7 + - "3": unmask bit [3:0] of LFSR / triangle amplitude equal to 15 + - "4": unmask bit [4:0] of LFSR / triangle amplitude equal to 31 + - "5": unmask bit [5:0] of LFSR / triangle amplitude equal to 63 + - "6": unmask bit [6:0] of LFSR / triangle amplitude equal to 127 + - "7": unmask bit [7:0] of LFSR / triangle amplitude equal to 255 + - "8": unmask bit [8:0] of LFSR / triangle amplitude equal to 511 + - "9": unmask bit [9:0] of LFSR / triangle amplitude equal to 1023 + - "10": unmask bit [10:0] of LFSR / triangle amplitude equal to 2047 + - "11": unmask bit [11:0] of LFSR / triangle amplitude equal to 4095 diff --git a/drivers/iio/dac/stm32-dac.c b/drivers/iio/dac/stm32-dac.c index 62e43e9..d7dda78 100644 --- a/drivers/iio/dac/stm32-dac.c +++ b/drivers/iio/dac/stm32-dac.c @@ -41,10 +41,14 @@ /** * struct stm32_dac - private data of DAC driver * @common: reference to DAC common data + * @wave: waveform generator + * @mamp: waveform mask/amplitude * @swtrig: Using software trigger */ struct stm32_dac { struct stm32_dac_common *common; + u32 wave; + u32 mamp; bool swtrig; }; @@ -157,6 +161,24 @@ static int stm32_dac_is_enabled(struct stm32_dac *dac, int channel) return !!en; } +static int stm32_dac_wavegen(struct stm32_dac *dac, int channel) +{ + struct regmap *regmap = dac->common->regmap; + u32 mask, val; + + if (channel == STM32_DAC_CHANNEL_1) { + val = FIELD_PREP(STM32_DAC_CR_WAVE1, dac->wave) | + FIELD_PREP(STM32_DAC_CR_MAMP1, dac->mamp); + mask = STM32_DAC_CR_WAVE1 | STM32_DAC_CR_MAMP1; + } else { + val = FIELD_PREP(STM32_DAC_CR_WAVE2, dac->wave) | + FIELD_PREP(STM32_DAC_CR_MAMP2, dac->mamp); + mask = STM32_DAC_CR_WAVE2 | STM32_DAC_CR_MAMP2; + } + + return regmap_update_bits(regmap, STM32_DAC_CR, mask, val); +} + static int stm32_dac_enable(struct iio_dev *indio_dev, int channel) { struct stm32_dac *dac = iio_priv(indio_dev); @@ -164,6 +186,17 @@ static int stm32_dac_enable(struct iio_dev *indio_dev, int channel) STM32_DAC_CR_EN1 : STM32_DAC_CR_EN2; int ret; + if (dac->wave && !indio_dev->trig) { + dev_err(&indio_dev->dev, "Wavegen requires a trigger\n"); + return -EINVAL; + } + + ret = stm32_dac_wavegen(dac, channel); + if (ret < 0) { + dev_err(&indio_dev->dev, "Wavegen setup failed\n"); + return ret; + } + ret = stm32_dac_set_trig(dac, indio_dev->trig, channel); if (ret < 0) { dev_err(&indio_dev->dev, "Trigger setup failed\n"); @@ -291,6 +324,96 @@ static int stm32_dac_debugfs_reg_access(struct iio_dev *indio_dev, .driver_module = THIS_MODULE, }; +/* waveform generator wave selection */ +static const char * const stm32_dac_wave_desc[] = { + "none", + "noise", + "triangle", +}; + +static int stm32_dac_set_wave(struct iio_dev *indio_dev, + const struct iio_chan_spec *chan, + unsigned int type) +{ + struct stm32_dac *dac = iio_priv(indio_dev); + + if (stm32_dac_is_enabled(dac, chan->channel)) + return -EBUSY; + dac->wave = type; + + return 0; +} + +static int stm32_dac_get_wave(struct iio_dev *indio_dev, + const struct iio_chan_spec *chan) +{ + struct stm32_dac *dac = iio_priv(indio_dev); + + return dac->wave; +} + +static const struct iio_enum stm32_dac_wave_enum = { + .items = stm32_dac_wave_desc, + .num_items = ARRAY_SIZE(stm32_dac_wave_desc), + .get = stm32_dac_get_wave, + .set = stm32_dac_set_wave, +}; + +/* + * waveform generator mask/amplitude selection: + * - 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_mamp_desc[] = { + "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "10", "11", +}; + +static int stm32_dac_set_mamp(struct iio_dev *indio_dev, + const struct iio_chan_spec *chan, + unsigned int type) +{ + struct stm32_dac *dac = iio_priv(indio_dev); + + if (stm32_dac_is_enabled(dac, chan->channel)) + return -EBUSY; + dac->mamp = type; + + return 0; +} + +static int stm32_dac_get_mamp(struct iio_dev *indio_dev, + const struct iio_chan_spec *chan) +{ + struct stm32_dac *dac = iio_priv(indio_dev); + + return dac->mamp; +} + +static const struct iio_enum stm32_dac_mamp_enum = { + .items = stm32_dac_mamp_desc, + .num_items = ARRAY_SIZE(stm32_dac_mamp_desc), + .get = stm32_dac_get_mamp, + .set = stm32_dac_set_mamp, +}; + +static const struct iio_chan_spec_ext_info stm32_dac_ext_info[] = { + IIO_ENUM("wave", IIO_SHARED_BY_ALL, &stm32_dac_wave_enum), + { + .name = "wave_available", + .shared = IIO_SHARED_BY_ALL, + .read = iio_enum_available_read, + .private = (uintptr_t)&stm32_dac_wave_enum, + }, + IIO_ENUM("mamp", IIO_SHARED_BY_ALL, &stm32_dac_mamp_enum), + { + .name = "mamp_available", + .shared = IIO_SHARED_BY_ALL, + .read = iio_enum_available_read, + .private = (uintptr_t)&stm32_dac_mamp_enum, + }, + {}, +}; + #define STM32_DAC_CHANNEL(chan, name) { \ .type = IIO_VOLTAGE, \ .indexed = 1, \ @@ -306,6 +429,7 @@ static int stm32_dac_debugfs_reg_access(struct iio_dev *indio_dev, .storagebits = 16, \ }, \ .datasheet_name = name, \ + .ext_info = stm32_dac_ext_info \ } static const struct iio_chan_spec stm32_dac_channels[] = { -- 1.9.1
