* [PATCH v4 1/4] iio: adc: ad4000: Add support for SPI offload
2025-03-27 21:24 [PATCH v4 0/4] iio: adc: ad4000: Add SPI offload support Marcelo Schmitt
@ 2025-03-27 21:24 ` Marcelo Schmitt
2025-04-09 17:22 ` David Lechner
2025-03-27 21:24 ` [PATCH v4 2/4] Documentation: iio: ad4000: Add new supported parts Marcelo Schmitt
` (3 subsequent siblings)
4 siblings, 1 reply; 9+ messages in thread
From: Marcelo Schmitt @ 2025-03-27 21:24 UTC (permalink / raw)
To: linux-iio, linux-doc, linux-kernel
Cc: jic23, lars, Michael.Hennerich, corbet, dlechner,
marcelo.schmitt1
FPGA HDL projects can include a PWM generator in addition to SPI-Engine.
The PWM IP is used to trigger SPI-Engine offload modules that in turn set
SPI-Engine to execute transfers to poll data from the ADC. That allows data
to be read at the maximum sample rates. Also, it is possible to set a
specific sample rate by setting the proper PWM duty cycle and related state
parameters, thus allowing an adjustable ADC sample rate when a PWM (offload
trigger) is used in combination with SPI-Engine.
Add support for SPI offload.
Signed-off-by: Marcelo Schmitt <marcelo.schmitt@analog.com>
---
drivers/iio/adc/Kconfig | 7 +-
drivers/iio/adc/ad4000.c | 382 +++++++++++++++++++++++++++++++++++----
2 files changed, 354 insertions(+), 35 deletions(-)
diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 75ed633a3c43..eb0ba7457084 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -25,10 +25,15 @@ config AD4000
tristate "Analog Devices AD4000 ADC Driver"
depends on SPI
select IIO_BUFFER
+ select IIO_BUFFER_DMAENGINE
select IIO_TRIGGERED_BUFFER
+ select SPI_OFFLOAD
help
Say yes here to build support for Analog Devices AD4000 high speed
- SPI analog to digital converters (ADC).
+ SPI analog to digital converters (ADC). If intended to use with
+ SPI offloading support, it is recommended to enable
+ CONFIG_SPI_AXI_SPI_ENGINE, CONFIG_PWM_AXI_PWMGEN, and
+ CONFIG_SPI_OFFLOAD_TRIGGER_PWM.
To compile this driver as a module, choose M here: the module will be
called ad4000.
diff --git a/drivers/iio/adc/ad4000.c b/drivers/iio/adc/ad4000.c
index 4fe8dee48da9..e69a9d2a3e8c 100644
--- a/drivers/iio/adc/ad4000.c
+++ b/drivers/iio/adc/ad4000.c
@@ -15,12 +15,14 @@
#include <linux/mod_devicetable.h>
#include <linux/gpio/consumer.h>
#include <linux/regulator/consumer.h>
+#include <linux/spi/offload/consumer.h>
#include <linux/spi/spi.h>
#include <linux/units.h>
#include <linux/util_macros.h>
-#include <linux/iio/iio.h>
+#include <linux/iio/iio.h>
#include <linux/iio/buffer.h>
+#include <linux/iio/buffer-dmaengine.h>
#include <linux/iio/triggered_buffer.h>
#include <linux/iio/trigger_consumer.h>
@@ -32,10 +34,11 @@
/* AD4000 Configuration Register programmable bits */
#define AD4000_CFG_SPAN_COMP BIT(3) /* Input span compression */
#define AD4000_CFG_HIGHZ BIT(2) /* High impedance mode */
+#define AD4000_CFG_TURBO BIT(1) /* Turbo mode */
#define AD4000_SCALE_OPTIONS 2
-#define __AD4000_DIFF_CHANNEL(_sign, _real_bits, _storage_bits, _reg_access) \
+#define __AD4000_DIFF_CHANNEL(_sign, _real_bits, _storage_bits, _reg_access, _offl)\
{ \
.type = IIO_VOLTAGE, \
.indexed = 1, \
@@ -43,54 +46,65 @@
.channel = 0, \
.channel2 = 1, \
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
- BIT(IIO_CHAN_INFO_SCALE), \
+ BIT(IIO_CHAN_INFO_SCALE) | \
+ (_offl ? BIT(IIO_CHAN_INFO_SAMP_FREQ) : 0), \
.info_mask_separate_available = _reg_access ? BIT(IIO_CHAN_INFO_SCALE) : 0,\
.scan_index = 0, \
.scan_type = { \
.sign = _sign, \
.realbits = _real_bits, \
.storagebits = _storage_bits, \
- .shift = _storage_bits - _real_bits, \
- .endianness = IIO_BE, \
+ .shift = (_offl ? 0 : _storage_bits - _real_bits), \
+ .endianness = _offl ? IIO_CPU : IIO_BE \
}, \
}
-#define AD4000_DIFF_CHANNEL(_sign, _real_bits, _reg_access) \
+#define AD4000_DIFF_CHANNEL(_sign, _real_bits, _reg_access, _offl) \
__AD4000_DIFF_CHANNEL((_sign), (_real_bits), \
- ((_real_bits) > 16 ? 32 : 16), (_reg_access))
+ (((_offl) || ((_real_bits) > 16)) ? 32 : 16), \
+ (_reg_access), (_offl))
+/*
+ * When SPI offload is configured, transfers are executed without CPU
+ * intervention so no soft timestamp can be recorded when transfers run.
+ * Because of that, the macros that set timestamp channel are only used when
+ * transfers are not offloaded.
+ */
#define AD4000_DIFF_CHANNELS(_sign, _real_bits, _reg_access) \
{ \
- AD4000_DIFF_CHANNEL(_sign, _real_bits, _reg_access), \
+ AD4000_DIFF_CHANNEL(_sign, _real_bits, _reg_access, 0), \
IIO_CHAN_SOFT_TIMESTAMP(1), \
}
-#define __AD4000_PSEUDO_DIFF_CHANNEL(_sign, _real_bits, _storage_bits, _reg_access)\
+#define __AD4000_PSEUDO_DIFF_CHANNEL(_sign, _real_bits, _storage_bits, \
+ _reg_access, _offl) \
{ \
.type = IIO_VOLTAGE, \
.indexed = 1, \
.channel = 0, \
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
BIT(IIO_CHAN_INFO_SCALE) | \
- BIT(IIO_CHAN_INFO_OFFSET), \
+ BIT(IIO_CHAN_INFO_OFFSET) | \
+ (_offl ? BIT(IIO_CHAN_INFO_SAMP_FREQ) : 0), \
.info_mask_separate_available = _reg_access ? BIT(IIO_CHAN_INFO_SCALE) : 0,\
.scan_index = 0, \
.scan_type = { \
.sign = _sign, \
.realbits = _real_bits, \
.storagebits = _storage_bits, \
- .shift = _storage_bits - _real_bits, \
- .endianness = IIO_BE, \
+ .shift = (_offl ? 0 : _storage_bits - _real_bits), \
+ .endianness = _offl ? IIO_CPU : IIO_BE \
}, \
}
-#define AD4000_PSEUDO_DIFF_CHANNEL(_sign, _real_bits, _reg_access) \
+#define AD4000_PSEUDO_DIFF_CHANNEL(_sign, _real_bits, _reg_access, _offl) \
__AD4000_PSEUDO_DIFF_CHANNEL((_sign), (_real_bits), \
- ((_real_bits) > 16 ? 32 : 16), (_reg_access))
+ (((_offl) || ((_real_bits) > 16)) ? 32 : 16),\
+ (_reg_access), (_offl))
#define AD4000_PSEUDO_DIFF_CHANNELS(_sign, _real_bits, _reg_access) \
{ \
- AD4000_PSEUDO_DIFF_CHANNEL(_sign, _real_bits, _reg_access), \
+ AD4000_PSEUDO_DIFF_CHANNEL(_sign, _real_bits, _reg_access, 0), \
IIO_CHAN_SOFT_TIMESTAMP(1), \
}
@@ -184,212 +198,298 @@ struct ad4000_chip_info {
const char *dev_name;
struct iio_chan_spec chan_spec[2];
struct iio_chan_spec reg_access_chan_spec[2];
+ struct iio_chan_spec offload_chan_spec;
+ struct iio_chan_spec reg_access_offload_chan_spec;
const struct ad4000_time_spec *time_spec;
bool has_hardware_gain;
+ int max_rate_hz;
};
static const struct ad4000_chip_info ad4000_chip_info = {
.dev_name = "ad4000",
.chan_spec = AD4000_PSEUDO_DIFF_CHANNELS('u', 16, 0),
.reg_access_chan_spec = AD4000_PSEUDO_DIFF_CHANNELS('u', 16, 1),
+ .offload_chan_spec = AD4000_PSEUDO_DIFF_CHANNEL('u', 16, 0, 1),
+ .reg_access_offload_chan_spec = AD4000_PSEUDO_DIFF_CHANNEL('u', 16, 1, 1),
.time_spec = &ad4000_t_spec,
+ .max_rate_hz = 2 * MEGA,
};
static const struct ad4000_chip_info ad4001_chip_info = {
.dev_name = "ad4001",
.chan_spec = AD4000_DIFF_CHANNELS('s', 16, 0),
.reg_access_chan_spec = AD4000_DIFF_CHANNELS('s', 16, 1),
+ .offload_chan_spec = AD4000_DIFF_CHANNEL('s', 16, 0, 1),
+ .reg_access_offload_chan_spec = AD4000_DIFF_CHANNEL('s', 16, 1, 1),
.time_spec = &ad4000_t_spec,
+ .max_rate_hz = 2 * MEGA,
};
static const struct ad4000_chip_info ad4002_chip_info = {
.dev_name = "ad4002",
.chan_spec = AD4000_PSEUDO_DIFF_CHANNELS('u', 18, 0),
.reg_access_chan_spec = AD4000_PSEUDO_DIFF_CHANNELS('u', 18, 1),
+ .offload_chan_spec = AD4000_PSEUDO_DIFF_CHANNEL('u', 18, 0, 1),
+ .reg_access_offload_chan_spec = AD4000_PSEUDO_DIFF_CHANNEL('u', 18, 1, 1),
.time_spec = &ad4000_t_spec,
+ .max_rate_hz = 2 * MEGA,
};
static const struct ad4000_chip_info ad4003_chip_info = {
.dev_name = "ad4003",
.chan_spec = AD4000_DIFF_CHANNELS('s', 18, 0),
.reg_access_chan_spec = AD4000_DIFF_CHANNELS('s', 18, 1),
+ .offload_chan_spec = AD4000_DIFF_CHANNEL('s', 18, 0, 1),
+ .reg_access_offload_chan_spec = AD4000_DIFF_CHANNEL('s', 18, 1, 1),
.time_spec = &ad4000_t_spec,
+ .max_rate_hz = 2 * MEGA,
};
static const struct ad4000_chip_info ad4004_chip_info = {
.dev_name = "ad4004",
.chan_spec = AD4000_PSEUDO_DIFF_CHANNELS('u', 16, 0),
.reg_access_chan_spec = AD4000_PSEUDO_DIFF_CHANNELS('u', 16, 1),
+ .offload_chan_spec = AD4000_PSEUDO_DIFF_CHANNEL('u', 16, 0, 1),
+ .reg_access_offload_chan_spec = AD4000_PSEUDO_DIFF_CHANNEL('u', 16, 1, 1),
.time_spec = &ad4000_t_spec,
+ .max_rate_hz = 1 * MEGA,
};
static const struct ad4000_chip_info ad4005_chip_info = {
.dev_name = "ad4005",
.chan_spec = AD4000_DIFF_CHANNELS('s', 16, 0),
.reg_access_chan_spec = AD4000_DIFF_CHANNELS('s', 16, 1),
+ .offload_chan_spec = AD4000_DIFF_CHANNEL('s', 16, 0, 1),
+ .reg_access_offload_chan_spec = AD4000_DIFF_CHANNEL('s', 16, 1, 1),
.time_spec = &ad4000_t_spec,
+ .max_rate_hz = 1 * MEGA,
};
static const struct ad4000_chip_info ad4006_chip_info = {
.dev_name = "ad4006",
.chan_spec = AD4000_PSEUDO_DIFF_CHANNELS('u', 18, 0),
.reg_access_chan_spec = AD4000_PSEUDO_DIFF_CHANNELS('u', 18, 1),
+ .offload_chan_spec = AD4000_PSEUDO_DIFF_CHANNEL('u', 18, 0, 1),
+ .reg_access_offload_chan_spec = AD4000_PSEUDO_DIFF_CHANNEL('u', 18, 1, 1),
.time_spec = &ad4000_t_spec,
+ .max_rate_hz = 1 * MEGA,
};
static const struct ad4000_chip_info ad4007_chip_info = {
.dev_name = "ad4007",
.chan_spec = AD4000_DIFF_CHANNELS('s', 18, 0),
.reg_access_chan_spec = AD4000_DIFF_CHANNELS('s', 18, 1),
+ .offload_chan_spec = AD4000_DIFF_CHANNEL('s', 18, 0, 1),
+ .reg_access_offload_chan_spec = AD4000_DIFF_CHANNEL('s', 18, 1, 1),
.time_spec = &ad4000_t_spec,
+ .max_rate_hz = 1 * MEGA,
};
static const struct ad4000_chip_info ad4008_chip_info = {
.dev_name = "ad4008",
.chan_spec = AD4000_PSEUDO_DIFF_CHANNELS('u', 16, 0),
.reg_access_chan_spec = AD4000_PSEUDO_DIFF_CHANNELS('u', 16, 1),
+ .offload_chan_spec = AD4000_PSEUDO_DIFF_CHANNEL('u', 16, 0, 1),
+ .reg_access_offload_chan_spec = AD4000_PSEUDO_DIFF_CHANNEL('u', 16, 1, 1),
.time_spec = &ad4000_t_spec,
+ .max_rate_hz = 500 * KILO,
};
static const struct ad4000_chip_info ad4010_chip_info = {
.dev_name = "ad4010",
.chan_spec = AD4000_PSEUDO_DIFF_CHANNELS('u', 18, 0),
.reg_access_chan_spec = AD4000_PSEUDO_DIFF_CHANNELS('u', 18, 1),
+ .offload_chan_spec = AD4000_PSEUDO_DIFF_CHANNEL('u', 18, 0, 1),
+ .reg_access_offload_chan_spec = AD4000_PSEUDO_DIFF_CHANNEL('u', 18, 1, 1),
.time_spec = &ad4000_t_spec,
+ .max_rate_hz = 500 * KILO,
};
static const struct ad4000_chip_info ad4011_chip_info = {
.dev_name = "ad4011",
.chan_spec = AD4000_DIFF_CHANNELS('s', 18, 0),
.reg_access_chan_spec = AD4000_DIFF_CHANNELS('s', 18, 1),
+ .offload_chan_spec = AD4000_DIFF_CHANNEL('s', 18, 0, 1),
+ .reg_access_offload_chan_spec = AD4000_DIFF_CHANNEL('s', 18, 1, 1),
.time_spec = &ad4000_t_spec,
+ .max_rate_hz = 500 * KILO,
};
static const struct ad4000_chip_info ad4020_chip_info = {
.dev_name = "ad4020",
.chan_spec = AD4000_DIFF_CHANNELS('s', 20, 0),
.reg_access_chan_spec = AD4000_DIFF_CHANNELS('s', 20, 1),
+ .offload_chan_spec = AD4000_DIFF_CHANNEL('s', 20, 0, 1),
+ .reg_access_offload_chan_spec = AD4000_DIFF_CHANNEL('s', 20, 1, 1),
.time_spec = &ad4020_t_spec,
+ .max_rate_hz = 1800 * KILO,
};
static const struct ad4000_chip_info ad4021_chip_info = {
.dev_name = "ad4021",
.chan_spec = AD4000_DIFF_CHANNELS('s', 20, 0),
.reg_access_chan_spec = AD4000_DIFF_CHANNELS('s', 20, 1),
+ .offload_chan_spec = AD4000_DIFF_CHANNEL('s', 20, 0, 1),
+ .reg_access_offload_chan_spec = AD4000_DIFF_CHANNEL('s', 20, 1, 1),
.time_spec = &ad4020_t_spec,
+ .max_rate_hz = 1 * MEGA,
};
static const struct ad4000_chip_info ad4022_chip_info = {
.dev_name = "ad4022",
.chan_spec = AD4000_DIFF_CHANNELS('s', 20, 0),
.reg_access_chan_spec = AD4000_DIFF_CHANNELS('s', 20, 1),
+ .offload_chan_spec = AD4000_DIFF_CHANNEL('s', 20, 0, 1),
+ .reg_access_offload_chan_spec = AD4000_DIFF_CHANNEL('s', 20, 1, 1),
.time_spec = &ad4020_t_spec,
+ .max_rate_hz = 500 * KILO,
};
static const struct ad4000_chip_info adaq4001_chip_info = {
.dev_name = "adaq4001",
.chan_spec = AD4000_DIFF_CHANNELS('s', 16, 0),
.reg_access_chan_spec = AD4000_DIFF_CHANNELS('s', 16, 1),
+ .offload_chan_spec = AD4000_DIFF_CHANNEL('s', 16, 0, 1),
+ .reg_access_offload_chan_spec = AD4000_DIFF_CHANNEL('s', 16, 1, 1),
.time_spec = &ad4000_t_spec,
.has_hardware_gain = true,
+ .max_rate_hz = 2 * MEGA,
};
static const struct ad4000_chip_info adaq4003_chip_info = {
.dev_name = "adaq4003",
.chan_spec = AD4000_DIFF_CHANNELS('s', 18, 0),
.reg_access_chan_spec = AD4000_DIFF_CHANNELS('s', 18, 1),
+ .offload_chan_spec = AD4000_DIFF_CHANNEL('s', 18, 0, 1),
+ .reg_access_offload_chan_spec = AD4000_DIFF_CHANNEL('s', 18, 1, 1),
.time_spec = &ad4000_t_spec,
.has_hardware_gain = true,
+ .max_rate_hz = 2 * MEGA,
};
static const struct ad4000_chip_info ad7685_chip_info = {
.dev_name = "ad7685",
.chan_spec = AD4000_PSEUDO_DIFF_CHANNELS('u', 16, 0),
+ .offload_chan_spec = AD4000_PSEUDO_DIFF_CHANNEL('u', 16, 0, 1),
.time_spec = &ad7687_t_spec,
+ .max_rate_hz = 250 * KILO,
};
static const struct ad4000_chip_info ad7686_chip_info = {
.dev_name = "ad7686",
.chan_spec = AD4000_PSEUDO_DIFF_CHANNELS('u', 16, 0),
+ .offload_chan_spec = AD4000_PSEUDO_DIFF_CHANNEL('u', 16, 0, 1),
.time_spec = &ad7686_t_spec,
+ .max_rate_hz = 500 * KILO,
};
static const struct ad4000_chip_info ad7687_chip_info = {
.dev_name = "ad7687",
.chan_spec = AD4000_DIFF_CHANNELS('s', 16, 0),
+ .offload_chan_spec = AD4000_DIFF_CHANNEL('s', 16, 0, 1),
.time_spec = &ad7687_t_spec,
+ .max_rate_hz = 250 * KILO,
};
static const struct ad4000_chip_info ad7688_chip_info = {
.dev_name = "ad7688",
.chan_spec = AD4000_DIFF_CHANNELS('s', 16, 0),
+ .offload_chan_spec = AD4000_DIFF_CHANNEL('s', 16, 0, 1),
.time_spec = &ad7686_t_spec,
+ .max_rate_hz = 500 * KILO,
};
static const struct ad4000_chip_info ad7690_chip_info = {
.dev_name = "ad7690",
.chan_spec = AD4000_DIFF_CHANNELS('s', 18, 0),
+ .offload_chan_spec = AD4000_DIFF_CHANNEL('s', 18, 0, 1),
.time_spec = &ad7690_t_spec,
+ .max_rate_hz = 400 * KILO,
};
static const struct ad4000_chip_info ad7691_chip_info = {
.dev_name = "ad7691",
.chan_spec = AD4000_DIFF_CHANNELS('s', 18, 0),
+ .offload_chan_spec = AD4000_DIFF_CHANNEL('s', 18, 0, 1),
.time_spec = &ad7691_t_spec,
+ .max_rate_hz = 250 * KILO,
};
static const struct ad4000_chip_info ad7693_chip_info = {
.dev_name = "ad7693",
.chan_spec = AD4000_DIFF_CHANNELS('s', 16, 0),
+ .offload_chan_spec = AD4000_DIFF_CHANNEL('s', 16, 0, 1),
.time_spec = &ad7686_t_spec,
+ .max_rate_hz = 500 * KILO,
};
static const struct ad4000_chip_info ad7942_chip_info = {
.dev_name = "ad7942",
.chan_spec = AD4000_PSEUDO_DIFF_CHANNELS('u', 14, 0),
+ .offload_chan_spec = AD4000_PSEUDO_DIFF_CHANNEL('u', 14, 0, 1),
.time_spec = &ad7687_t_spec,
+ .max_rate_hz = 250 * KILO,
};
static const struct ad4000_chip_info ad7946_chip_info = {
.dev_name = "ad7946",
.chan_spec = AD4000_PSEUDO_DIFF_CHANNELS('u', 14, 0),
+ .offload_chan_spec = AD4000_PSEUDO_DIFF_CHANNEL('u', 14, 0, 1),
.time_spec = &ad7686_t_spec,
+ .max_rate_hz = 500 * KILO,
};
static const struct ad4000_chip_info ad7980_chip_info = {
.dev_name = "ad7980",
.chan_spec = AD4000_PSEUDO_DIFF_CHANNELS('u', 16, 0),
+ .offload_chan_spec = AD4000_PSEUDO_DIFF_CHANNEL('u', 16, 0, 1),
.time_spec = &ad7980_t_spec,
+ .max_rate_hz = 1 * MEGA,
};
static const struct ad4000_chip_info ad7982_chip_info = {
.dev_name = "ad7982",
.chan_spec = AD4000_DIFF_CHANNELS('s', 18, 0),
+ .offload_chan_spec = AD4000_DIFF_CHANNEL('s', 18, 0, 1),
.time_spec = &ad7980_t_spec,
+ .max_rate_hz = 1 * MEGA,
};
static const struct ad4000_chip_info ad7983_chip_info = {
.dev_name = "ad7983",
.chan_spec = AD4000_PSEUDO_DIFF_CHANNELS('u', 16, 0),
+ .offload_chan_spec = AD4000_PSEUDO_DIFF_CHANNEL('u', 16, 0, 1),
.time_spec = &ad7983_t_spec,
+ .max_rate_hz = 1 * MEGA + 333 * KILO + 333,
};
static const struct ad4000_chip_info ad7984_chip_info = {
.dev_name = "ad7984",
.chan_spec = AD4000_DIFF_CHANNELS('s', 18, 0),
+ .offload_chan_spec = AD4000_DIFF_CHANNEL('s', 18, 0, 1),
.time_spec = &ad7983_t_spec,
+ .max_rate_hz = 1 * MEGA + 333 * KILO + 333,
};
static const struct ad4000_chip_info ad7988_1_chip_info = {
.dev_name = "ad7988-1",
.chan_spec = AD4000_PSEUDO_DIFF_CHANNELS('u', 16, 0),
+ .offload_chan_spec = AD4000_PSEUDO_DIFF_CHANNEL('u', 16, 0, 1),
.time_spec = &ad7988_1_t_spec,
+ .max_rate_hz = 100 * KILO,
};
static const struct ad4000_chip_info ad7988_5_chip_info = {
.dev_name = "ad7988-5",
.chan_spec = AD4000_PSEUDO_DIFF_CHANNELS('u', 16, 0),
+ .offload_chan_spec = AD4000_PSEUDO_DIFF_CHANNEL('u', 16, 0, 1),
.time_spec = &ad7686_t_spec,
+ .max_rate_hz = 500 * KILO,
+};
+
+static const struct spi_offload_config ad4000_offload_config = {
+ .capability_flags = SPI_OFFLOAD_CAP_TRIGGER |
+ SPI_OFFLOAD_CAP_RX_STREAM_DMA,
};
struct ad4000_state {
@@ -397,6 +497,13 @@ struct ad4000_state {
struct gpio_desc *cnv_gpio;
struct spi_transfer xfers[2];
struct spi_message msg;
+ struct spi_transfer offload_xfer;
+ struct spi_message offload_msg;
+ struct spi_offload *offload;
+ struct spi_offload_trigger *offload_trigger;
+ bool using_offload;
+ unsigned long offload_trigger_hz;
+ int max_rate_hz;
struct mutex lock; /* Protect read modify write cycle */
int vref_mv;
enum ad4000_sdi sdi_pin;
@@ -411,8 +518,10 @@ struct ad4000_state {
*/
struct {
union {
- __be16 sample_buf16;
- __be32 sample_buf32;
+ __be16 sample_buf16_be;
+ __be32 sample_buf32_be;
+ u16 sample_buf16;
+ u32 sample_buf32;
} data;
aligned_s64 timestamp;
} scan __aligned(IIO_DMA_MINALIGN);
@@ -487,6 +596,25 @@ static int ad4000_read_reg(struct ad4000_state *st, unsigned int *val)
return ret;
}
+static int ad4000_set_sampling_freq(struct ad4000_state *st, int freq)
+{
+ struct spi_offload_trigger_config config = {
+ .type = SPI_OFFLOAD_TRIGGER_PERIODIC,
+ .periodic = {
+ .frequency_hz = freq,
+ },
+ };
+ int ret;
+
+ ret = spi_offload_trigger_validate(st->offload_trigger, &config);
+ if (ret)
+ return ret;
+
+ st->offload_trigger_hz = config.periodic.frequency_hz;
+
+ return 0;
+}
+
static int ad4000_convert_and_acquire(struct ad4000_state *st)
{
int ret;
@@ -515,10 +643,17 @@ static int ad4000_single_conversion(struct iio_dev *indio_dev,
if (ret < 0)
return ret;
- if (chan->scan_type.storagebits > 16)
- sample = be32_to_cpu(st->scan.data.sample_buf32);
- else
- sample = be16_to_cpu(st->scan.data.sample_buf16);
+ if (chan->scan_type.endianness == IIO_BE) {
+ if (chan->scan_type.realbits > 16)
+ sample = be32_to_cpu(st->scan.data.sample_buf32_be);
+ else
+ sample = be16_to_cpu(st->scan.data.sample_buf16_be);
+ } else {
+ if (chan->scan_type.realbits > 16)
+ sample = st->scan.data.sample_buf32;
+ else
+ sample = st->scan.data.sample_buf16;
+ }
sample >>= chan->scan_type.shift;
@@ -554,6 +689,9 @@ static int ad4000_read_raw(struct iio_dev *indio_dev,
if (st->span_comp)
*val = mult_frac(st->vref_mv, 1, 10);
+ return IIO_VAL_INT;
+ case IIO_CHAN_INFO_SAMP_FREQ:
+ *val = st->offload_trigger_hz;
return IIO_VAL_INT;
default:
return -EINVAL;
@@ -620,6 +758,7 @@ static int ad4000_write_raw(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan,
int val, int val2, long mask)
{
+ struct ad4000_state *st = iio_priv(indio_dev);
int ret;
switch (mask) {
@@ -629,6 +768,15 @@ static int ad4000_write_raw(struct iio_dev *indio_dev,
ret = __ad4000_write_raw(indio_dev, chan, val2);
iio_device_release_direct(indio_dev);
return ret;
+ case IIO_CHAN_INFO_SAMP_FREQ:
+ if (val < 1 || val > st->max_rate_hz)
+ return -EINVAL;
+
+ if (!iio_device_claim_direct(indio_dev))
+ return -EBUSY;
+ ret = ad4000_set_sampling_freq(st, val);
+ iio_device_release_direct(indio_dev);
+ return ret;
default:
return -EINVAL;
}
@@ -659,10 +807,114 @@ static const struct iio_info ad4000_reg_access_info = {
.write_raw_get_fmt = &ad4000_write_raw_get_fmt,
};
+static const struct iio_info ad4000_offload_info = {
+ .read_raw = &ad4000_read_raw,
+ .write_raw = &ad4000_write_raw,
+ .write_raw_get_fmt = &ad4000_write_raw_get_fmt,
+};
+
static const struct iio_info ad4000_info = {
.read_raw = &ad4000_read_raw,
};
+static int ad4000_offload_buffer_postenable(struct iio_dev *indio_dev)
+{
+ struct ad4000_state *st = iio_priv(indio_dev);
+ struct spi_offload_trigger_config config = {
+ .type = SPI_OFFLOAD_TRIGGER_PERIODIC,
+ .periodic = {
+ .frequency_hz = st->offload_trigger_hz,
+ },
+ };
+
+ return spi_offload_trigger_enable(st->offload, st->offload_trigger,
+ &config);
+}
+
+static int ad4000_offload_buffer_predisable(struct iio_dev *indio_dev)
+{
+ struct ad4000_state *st = iio_priv(indio_dev);
+
+ spi_offload_trigger_disable(st->offload, st->offload_trigger);
+
+ return 0;
+}
+
+static const struct iio_buffer_setup_ops ad4000_offload_buffer_setup_ops = {
+ .postenable = &ad4000_offload_buffer_postenable,
+ .predisable = &ad4000_offload_buffer_predisable,
+};
+
+static int ad4000_spi_offload_setup(struct iio_dev *indio_dev,
+ struct ad4000_state *st)
+{
+ struct spi_device *spi = st->spi;
+ struct device *dev = &spi->dev;
+ struct dma_chan *rx_dma;
+ int ret;
+
+ st->offload_trigger = devm_spi_offload_trigger_get(dev, st->offload,
+ SPI_OFFLOAD_TRIGGER_PERIODIC);
+ if (IS_ERR(st->offload_trigger))
+ return dev_err_probe(dev, PTR_ERR(st->offload_trigger),
+ "Failed to get offload trigger\n");
+
+ ret = ad4000_set_sampling_freq(st, st->max_rate_hz);
+ if (ret)
+ return dev_err_probe(dev, ret,
+ "Failed to set sampling frequency\n");
+
+ rx_dma = devm_spi_offload_rx_stream_request_dma_chan(dev, st->offload);
+ if (IS_ERR(rx_dma))
+ return dev_err_probe(dev, PTR_ERR(rx_dma),
+ "Failed to get offload RX DMA\n");
+
+ ret = devm_iio_dmaengine_buffer_setup_with_handle(dev, indio_dev, rx_dma,
+ IIO_BUFFER_DIRECTION_IN);
+ if (ret)
+ return dev_err_probe(dev, ret, "Failed to setup DMA buffer\n");
+
+ return 0;
+}
+
+/*
+ * This executes a data sample transfer when using SPI offloading. The device
+ * connections should be in "3-wire" mode, selected either when the adi,sdi-pin
+ * device tree property is absent or set to "high". Also, the ADC CNV pin must
+ * be connected to a SPI controller CS (it can't be connected to a GPIO).
+ *
+ * In order to achieve the maximum sample rate, we only do one transfer per
+ * SPI offload trigger. Because the ADC output has a one sample latency (delay)
+ * when the device is wired in "3-wire" mode and only one transfer per sample is
+ * being made in turbo mode, the first data sample is not valid because it
+ * contains the output of an earlier conversion result. We also set transfer
+ * `bits_per_word` to achieve higher throughput by using the minimum number of
+ * SCLK cycles. Also, a delay is added to make sure we meet the minimum quiet
+ * time before releasing the CS line.
+ *
+ * Note that, with `bits_per_word` set to the number of ADC precision bits,
+ * transfers use larger word sizes that get stored in 'in-memory wordsizes' that
+ * are always in native CPU byte order. Because of that, IIO buffer elements
+ * ought to be read in CPU endianness which requires setting IIO scan_type
+ * endianness accordingly (i.e. IIO_CPU).
+ */
+static int ad4000_prepare_offload_message(struct ad4000_state *st,
+ const struct iio_chan_spec *chan)
+{
+ struct spi_transfer *xfer = &st->offload_xfer;
+
+ xfer->bits_per_word = chan->scan_type.realbits;
+ xfer->len = chan->scan_type.realbits > 16 ? 4 : 2;
+ xfer->delay.value = st->time_spec->t_quiet2_ns;
+ xfer->delay.unit = SPI_DELAY_UNIT_NSECS;
+ xfer->offload_flags = SPI_OFFLOAD_XFER_RX_STREAM;
+
+ spi_message_init_with_transfers(&st->offload_msg, xfer, 1);
+ st->offload_msg.offload = st->offload;
+
+ return devm_spi_optimize_message(&st->spi->dev, st->spi, &st->offload_msg);
+}
+
/*
* This executes a data sample transfer for when the device connections are
* in "3-wire" mode, selected when the adi,sdi-pin device tree property is
@@ -690,6 +942,15 @@ static int ad4000_prepare_3wire_mode_message(struct ad4000_state *st,
xfers[1].rx_buf = &st->scan.data;
xfers[1].len = BITS_TO_BYTES(chan->scan_type.storagebits);
+
+ /*
+ * If the device is set up for SPI offloading, IIO channel scan_type is
+ * set to IIO_CPU. When that is the case, use larger SPI word sizes for
+ * single-shot reads too. Thus, sample data can be correctly handled in
+ * ad4000_single_conversion() according to scan_type endianness.
+ */
+ if (chan->scan_type.endianness != IIO_BE)
+ xfers[1].bits_per_word = chan->scan_type.realbits;
xfers[1].delay.value = st->time_spec->t_quiet2_ns;
xfers[1].delay.unit = SPI_DELAY_UNIT_NSECS;
@@ -733,6 +994,9 @@ static int ad4000_config(struct ad4000_state *st)
if (device_property_present(&st->spi->dev, "adi,high-z-input"))
reg_val |= FIELD_PREP(AD4000_CFG_HIGHZ, 1);
+ if (st->using_offload)
+ reg_val |= FIELD_PREP(AD4000_CFG_TURBO, 1);
+
return ad4000_write_reg(st, reg_val);
}
@@ -755,6 +1019,7 @@ static int ad4000_probe(struct spi_device *spi)
st = iio_priv(indio_dev);
st->spi = spi;
st->time_spec = chip->time_spec;
+ st->max_rate_hz = chip->max_rate_hz;
ret = devm_regulator_bulk_get_enable(dev, ARRAY_SIZE(ad4000_power_supplies),
ad4000_power_supplies);
@@ -772,6 +1037,26 @@ static int ad4000_probe(struct spi_device *spi)
return dev_err_probe(dev, PTR_ERR(st->cnv_gpio),
"Failed to get CNV GPIO");
+ st->offload = devm_spi_offload_get(dev, spi, &ad4000_offload_config);
+ ret = PTR_ERR_OR_ZERO(st->offload);
+ if (ret && ret != -ENODEV)
+ return dev_err_probe(dev, ret, "Failed to get offload\n");
+
+ st->using_offload = !IS_ERR(st->offload);
+ if (st->using_offload) {
+ indio_dev->setup_ops = &ad4000_offload_buffer_setup_ops;
+ ret = ad4000_spi_offload_setup(indio_dev, st);
+ if (ret)
+ return ret;
+ } else {
+ ret = devm_iio_triggered_buffer_setup(dev, indio_dev,
+ &iio_pollfunc_store_time,
+ &ad4000_trigger_handler,
+ NULL);
+ if (ret)
+ return ret;
+ }
+
ret = device_property_match_property_string(dev, "adi,sdi-pin",
ad4000_sdi_pin,
ARRAY_SIZE(ad4000_sdi_pin));
@@ -784,7 +1069,6 @@ static int ad4000_probe(struct spi_device *spi)
switch (st->sdi_pin) {
case AD4000_SDI_MOSI:
indio_dev->info = &ad4000_reg_access_info;
- indio_dev->channels = chip->reg_access_chan_spec;
/*
* In "3-wire mode", the ADC SDI line must be kept high when
@@ -796,9 +1080,26 @@ static int ad4000_probe(struct spi_device *spi)
if (ret < 0)
return ret;
+ if (st->using_offload) {
+ indio_dev->channels = &chip->reg_access_offload_chan_spec;
+ indio_dev->num_channels = 1;
+ ret = ad4000_prepare_offload_message(st, indio_dev->channels);
+ if (ret)
+ return dev_err_probe(dev, ret,
+ "Failed to optimize SPI msg\n");
+ } else {
+ indio_dev->channels = chip->reg_access_chan_spec;
+ indio_dev->num_channels = ARRAY_SIZE(chip->reg_access_chan_spec);
+ }
+
+ /*
+ * Call ad4000_prepare_3wire_mode_message() so single-shot read
+ * SPI messages are always initialized.
+ */
ret = ad4000_prepare_3wire_mode_message(st, &indio_dev->channels[0]);
if (ret)
- return ret;
+ return dev_err_probe(dev, ret,
+ "Failed to optimize SPI msg\n");
ret = ad4000_config(st);
if (ret < 0)
@@ -806,19 +1107,38 @@ static int ad4000_probe(struct spi_device *spi)
break;
case AD4000_SDI_VIO:
- indio_dev->info = &ad4000_info;
- indio_dev->channels = chip->chan_spec;
+ if (st->using_offload) {
+ indio_dev->info = &ad4000_offload_info;
+ indio_dev->channels = &chip->offload_chan_spec;
+ indio_dev->num_channels = 1;
+
+ ret = ad4000_prepare_offload_message(st, indio_dev->channels);
+ if (ret)
+ return dev_err_probe(dev, ret,
+ "Failed to optimize SPI msg\n");
+ } else {
+ indio_dev->info = &ad4000_info;
+ indio_dev->channels = chip->chan_spec;
+ indio_dev->num_channels = ARRAY_SIZE(chip->chan_spec);
+ }
+
ret = ad4000_prepare_3wire_mode_message(st, &indio_dev->channels[0]);
if (ret)
- return ret;
+ return dev_err_probe(dev, ret,
+ "Failed to optimize SPI msg\n");
break;
case AD4000_SDI_CS:
+ if (st->using_offload)
+ return dev_err_probe(dev, -EPROTONOSUPPORT,
+ "Unsupported sdi-pin + offload config\n");
indio_dev->info = &ad4000_info;
indio_dev->channels = chip->chan_spec;
+ indio_dev->num_channels = ARRAY_SIZE(chip->chan_spec);
ret = ad4000_prepare_4wire_mode_message(st, &indio_dev->channels[0]);
if (ret)
- return ret;
+ return dev_err_probe(dev, ret,
+ "Failed to optimize SPI msg\n");
break;
case AD4000_SDI_GND:
@@ -830,7 +1150,6 @@ static int ad4000_probe(struct spi_device *spi)
}
indio_dev->name = chip->dev_name;
- indio_dev->num_channels = 2;
ret = devm_mutex_init(dev, &st->lock);
if (ret)
@@ -853,12 +1172,6 @@ static int ad4000_probe(struct spi_device *spi)
ad4000_fill_scale_tbl(st, &indio_dev->channels[0]);
- ret = devm_iio_triggered_buffer_setup(dev, indio_dev,
- &iio_pollfunc_store_time,
- &ad4000_trigger_handler, NULL);
- if (ret)
- return ret;
-
return devm_iio_device_register(dev, indio_dev);
}
@@ -947,3 +1260,4 @@ module_spi_driver(ad4000_driver);
MODULE_AUTHOR("Marcelo Schmitt <marcelo.schmitt@analog.com>");
MODULE_DESCRIPTION("Analog Devices AD4000 ADC driver");
MODULE_LICENSE("GPL");
+MODULE_IMPORT_NS("IIO_DMAENGINE_BUFFER");
--
2.47.2
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