iio: adc: ad7606: add SPI offload support

Add SPI offload support for this family.

Signed-off-by: Angelo Dureghello <adureghello@baylibre.com>
Reviewed-by: David Lechner <dlechner@baylibre.com>
Link: https://patch.msgid.link/20250403-wip-bl-spi-offload-ad7606-v1-3-1b00cb638b12@baylibre.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/adc/Kconfig

@@ -289,6 +289,8 @@ config AD7606_IFACE_SPI
 	tristate "Analog Devices AD7606 ADC driver with spi interface support"
 	depends on SPI
 	select AD7606
+	select IIO_BUFFER_DMAENGINE
+	select SPI_OFFLOAD
 	help
 	  Say yes here to build spi interface support for Analog Devices:
 	  ad7605-4, ad7606, ad7606-6, ad7606-4 analog to digital converters (ADC).

drivers/iio/adc/ad7606.c

@@ -138,6 +138,7 @@ const struct ad7606_chip_info ad7606_6_info = {
 	.oversampling_avail = ad7606_oversampling_avail,
 	.oversampling_num = ARRAY_SIZE(ad7606_oversampling_avail),
 	.scale_setup_cb = ad7606_16bit_chan_scale_setup,
+	.offload_storagebits = 32,
 };
 EXPORT_SYMBOL_NS_GPL(ad7606_6_info, "IIO_AD7606");
 
@@ -149,6 +150,7 @@ const struct ad7606_chip_info ad7606_4_info = {
 	.oversampling_avail = ad7606_oversampling_avail,
 	.oversampling_num = ARRAY_SIZE(ad7606_oversampling_avail),
 	.scale_setup_cb = ad7606_16bit_chan_scale_setup,
+	.offload_storagebits = 32,
 };
 EXPORT_SYMBOL_NS_GPL(ad7606_4_info, "IIO_AD7606");
 
@@ -161,6 +163,7 @@ const struct ad7606_chip_info ad7606b_info = {
 	.oversampling_num = ARRAY_SIZE(ad7606_oversampling_avail),
 	.scale_setup_cb = ad7606_16bit_chan_scale_setup,
 	.sw_setup_cb = ad7606b_sw_mode_setup,
+	.offload_storagebits = 32,
 };
 EXPORT_SYMBOL_NS_GPL(ad7606b_info, "IIO_AD7606");
 
@@ -173,6 +176,7 @@ const struct ad7606_chip_info ad7606c_16_info = {
 	.oversampling_num = ARRAY_SIZE(ad7606_oversampling_avail),
 	.scale_setup_cb = ad7606c_16bit_chan_scale_setup,
 	.sw_setup_cb = ad7606b_sw_mode_setup,
+	.offload_storagebits = 32,
 };
 EXPORT_SYMBOL_NS_GPL(ad7606c_16_info, "IIO_AD7606");
 
@@ -184,6 +188,7 @@ const struct ad7606_chip_info ad7607_info = {
 	.oversampling_avail = ad7606_oversampling_avail,
 	.oversampling_num = ARRAY_SIZE(ad7606_oversampling_avail),
 	.scale_setup_cb = ad7607_chan_scale_setup,
+	.offload_storagebits = 32,
 };
 EXPORT_SYMBOL_NS_GPL(ad7607_info, "IIO_AD7606");
 
@@ -195,6 +200,7 @@ const struct ad7606_chip_info ad7608_info = {
 	.oversampling_avail = ad7606_oversampling_avail,
 	.oversampling_num = ARRAY_SIZE(ad7606_oversampling_avail),
 	.scale_setup_cb = ad7608_chan_scale_setup,
+	.offload_storagebits = 32,
 };
 EXPORT_SYMBOL_NS_GPL(ad7608_info, "IIO_AD7606");
 
@@ -206,6 +212,7 @@ const struct ad7606_chip_info ad7609_info = {
 	.oversampling_avail = ad7606_oversampling_avail,
 	.oversampling_num = ARRAY_SIZE(ad7606_oversampling_avail),
 	.scale_setup_cb = ad7609_chan_scale_setup,
+	.offload_storagebits = 32,
 };
 EXPORT_SYMBOL_NS_GPL(ad7609_info, "IIO_AD7606");
 
@@ -218,6 +225,7 @@ const struct ad7606_chip_info ad7606c_18_info = {
 	.oversampling_num = ARRAY_SIZE(ad7606_oversampling_avail),
 	.scale_setup_cb = ad7606c_18bit_chan_scale_setup,
 	.sw_setup_cb = ad7606b_sw_mode_setup,
+	.offload_storagebits = 32,
 };
 EXPORT_SYMBOL_NS_GPL(ad7606c_18_info, "IIO_AD7606");
 
@@ -232,6 +240,7 @@ const struct ad7606_chip_info ad7616_info = {
 	.os_req_reset = true,
 	.scale_setup_cb = ad7606_16bit_chan_scale_setup,
 	.sw_setup_cb = ad7616_sw_mode_setup,
+	.offload_storagebits = 16,
 };
 EXPORT_SYMBOL_NS_GPL(ad7616_info, "IIO_AD7606");
 
@@ -514,7 +523,7 @@ static int ad7606_pwm_set_high(struct ad7606_state *st)
 	return ret;
 }
 
-static int ad7606_pwm_set_low(struct ad7606_state *st)
+int ad7606_pwm_set_low(struct ad7606_state *st)
 {
 	struct pwm_state cnvst_pwm_state;
 	int ret;
@@ -527,8 +536,9 @@ static int ad7606_pwm_set_low(struct ad7606_state *st)
 
 	return ret;
 }
+EXPORT_SYMBOL_NS_GPL(ad7606_pwm_set_low, "IIO_AD7606");
 
-static int ad7606_pwm_set_swing(struct ad7606_state *st)
+int ad7606_pwm_set_swing(struct ad7606_state *st)
 {
 	struct pwm_state cnvst_pwm_state;
 
@@ -538,6 +548,7 @@ static int ad7606_pwm_set_swing(struct ad7606_state *st)
 
 	return pwm_apply_might_sleep(st->cnvst_pwm, &cnvst_pwm_state);
 }
+EXPORT_SYMBOL_NS_GPL(ad7606_pwm_set_swing, "IIO_AD7606");
 
 static bool ad7606_pwm_is_swinging(struct ad7606_state *st)
 {
@@ -626,7 +637,7 @@ static int ad7606_scan_direct(struct iio_dev *indio_dev, unsigned int ch,
 	 * will not happen because IIO_CHAN_INFO_RAW is not supported for the backend.
 	 * TODO: Add support for reading a single value when the backend is used.
 	 */
-	if (!st->back) {
+	if (st->trig) {
 		ret = wait_for_completion_timeout(&st->completion,
 						  msecs_to_jiffies(1000));
 		if (!ret) {
@@ -634,7 +645,12 @@ static int ad7606_scan_direct(struct iio_dev *indio_dev, unsigned int ch,
 			goto error_ret;
 		}
 	} else {
-		fsleep(1);
+		/*
+		 * If the BUSY interrupt is not available, wait enough time for
+		 * the longest possible conversion (max for the whole family is
+		 * around 350us).
+		 */
+		fsleep(400);
 	}
 
 	ret = ad7606_read_samples(st);
@@ -698,10 +714,6 @@ static int ad7606_read_raw(struct iio_dev *indio_dev,
 		*val = st->oversampling;
 		return IIO_VAL_INT;
 	case IIO_CHAN_INFO_SAMP_FREQ:
-		/*
-		 * TODO: return the real frequency intead of the requested one once
-		 * pwm_get_state_hw comes upstream.
-		 */
 		pwm_get_state(st->cnvst_pwm, &cnvst_pwm_state);
 		*val = DIV_ROUND_CLOSEST_ULL(NSEC_PER_SEC, cnvst_pwm_state.period);
 		return IIO_VAL_INT;
@@ -1196,7 +1208,7 @@ static int ad7606_probe_channels(struct iio_dev *indio_dev)
 	bool slow_bus;
 	int ret, i;
 
-	slow_bus = !st->bops->iio_backend_config;
+	slow_bus = !(st->bops->iio_backend_config || st->offload_en);
 	indio_dev->num_channels = st->chip_info->num_adc_channels;
 
 	/* Slow buses also get 1 more channel for soft timestamp */
@@ -1217,7 +1229,14 @@ static int ad7606_probe_channels(struct iio_dev *indio_dev)
 		chan->scan_index = i;
 		chan->scan_type.sign = 's';
 		chan->scan_type.realbits = st->chip_info->bits;
-		chan->scan_type.storagebits = st->chip_info->bits > 16 ? 32 : 16;
+		/*
+		 * If in SPI offload mode, storagebits are set based
+		 * on the spi-engine hw implementation.
+		 */
+		chan->scan_type.storagebits = st->offload_en ?
+			st->chip_info->offload_storagebits :
+			(st->chip_info->bits > 16 ? 32 : 16);
+
 		chan->scan_type.endianness = IIO_CPU;
 
 		if (indio_dev->modes & INDIO_DIRECT_MODE)
@@ -1335,6 +1354,13 @@ int ad7606_probe(struct device *dev, int irq, void __iomem *base_address,
 	indio_dev->modes = st->bops->iio_backend_config ? 0 : INDIO_DIRECT_MODE;
 	indio_dev->name = chip_info->name;
 
+	/* Using spi-engine with offload support ? */
+	if (st->bops->offload_config) {
+		ret = st->bops->offload_config(dev, indio_dev);
+		if (ret)
+			return ret;
+	}
+
 	ret = ad7606_probe_channels(indio_dev);
 	if (ret)
 		return ret;
@@ -1350,7 +1376,7 @@ int ad7606_probe(struct device *dev, int irq, void __iomem *base_address,
 	}
 
 	/* If convst pin is not defined, setup PWM. */
-	if (!st->gpio_convst) {
+	if (!st->gpio_convst || st->offload_en) {
 		st->cnvst_pwm = devm_pwm_get(dev, NULL);
 		if (IS_ERR(st->cnvst_pwm))
 			return PTR_ERR(st->cnvst_pwm);
@@ -1389,8 +1415,7 @@ int ad7606_probe(struct device *dev, int irq, void __iomem *base_address,
 			return ret;
 
 		indio_dev->setup_ops = &ad7606_backend_buffer_ops;
-	} else {
+	} else if (!st->offload_en) {
-
 		/* Reserve the PWM use only for backend (force gpio_convst definition) */
 		if (!st->gpio_convst)
 			return dev_err_probe(dev, -EINVAL,
@@ -1428,7 +1453,8 @@ int ad7606_probe(struct device *dev, int irq, void __iomem *base_address,
 	st->write_scale = ad7606_write_scale_hw;
 	st->write_os = ad7606_write_os_hw;
 
-	if (st->sw_mode_en) {
+	/* Offload needs 1 DOUT line, applying this setting in sw_setup_cb. */
+	if (st->sw_mode_en || st->offload_en) {
 		indio_dev->info = &ad7606_info_sw_mode;
 		st->chip_info->sw_setup_cb(indio_dev);
 	}

drivers/iio/adc/ad7606.h

@@ -60,6 +60,7 @@ typedef int (*ad7606_sw_setup_cb_t)(struct iio_dev *indio_dev);
  * @os_req_reset:	some devices require a reset to update oversampling
  * @init_delay_ms:	required delay in milliseconds for initialization
  *			after a restart
+ * @offload_storagebits: storage bits used by the offload hw implementation
  */
 struct ad7606_chip_info {
 	unsigned int			max_samplerate;
@@ -72,6 +73,7 @@ struct ad7606_chip_info {
 	unsigned int			oversampling_num;
 	bool				os_req_reset;
 	unsigned long			init_delay_ms;
+	u8				offload_storagebits;
 };
 
 /**
@@ -118,6 +120,8 @@ struct ad7606_chan_scale {
  * @trig:		The IIO trigger associated with the device.
  * @completion:		completion to indicate end of conversion
  * @data:		buffer for reading data from the device
+ * @offload_en:		SPI offload enabled
+ * @bus_data:		bus-specific variables
  * @d16:		be16 buffer for reading data from the device
  */
 struct ad7606_state {
@@ -145,6 +149,9 @@ struct ad7606_state {
 	struct iio_trigger		*trig;
 	struct completion		completion;
 
+	bool				offload_en;
+	void				*bus_data;
+
 	/*
 	 * DMA (thus cache coherency maintenance) may require the
 	 * transfer buffers to live in their own cache lines.
@@ -165,6 +172,8 @@ struct ad7606_state {
  * @read_block:		function pointer for reading blocks of data
  * @sw_mode_config:	pointer to a function which configured the device
  *			for software mode
+ * @offload_config:     function pointer for configuring offload support,
+ *			where any
  * @reg_read:		function pointer for reading spi register
  * @reg_write:		function pointer for writing spi register
  * @update_scan_mode:	function pointer for handling the calls to iio_info's
@@ -174,6 +183,7 @@ struct ad7606_state {
 struct ad7606_bus_ops {
 	/* more methods added in future? */
 	int (*iio_backend_config)(struct device *dev, struct iio_dev *indio_dev);
+	int (*offload_config)(struct device *dev, struct iio_dev *indio_dev);
 	int (*read_block)(struct device *dev, int num, void *data);
 	int (*sw_mode_config)(struct iio_dev *indio_dev);
 	int (*reg_read)(struct ad7606_state *st, unsigned int addr);
@@ -199,6 +209,8 @@ int ad7606_probe(struct device *dev, int irq, void __iomem *base_address,
 		 const struct ad7606_bus_ops *bops);
 
 int ad7606_reset(struct ad7606_state *st);
+int ad7606_pwm_set_swing(struct ad7606_state *st);
+int ad7606_pwm_set_low(struct ad7606_state *st);
 
 extern const struct ad7606_chip_info ad7605_4_info;
 extern const struct ad7606_chip_info ad7606_8_info;

drivers/iio/adc/ad7606_spi.c

@@ -6,15 +6,31 @@
  */
 
 #include <linux/err.h>
+#include <linux/math.h>
 #include <linux/module.h>
+#include <linux/pwm.h>
+#include <linux/spi/offload/consumer.h>
+#include <linux/spi/offload/provider.h>
 #include <linux/spi/spi.h>
 #include <linux/types.h>
+#include <linux/units.h>
 
+#include <linux/iio/buffer-dmaengine.h>
 #include <linux/iio/iio.h>
+
+#include <dt-bindings/iio/adc/adi,ad7606.h>
+
 #include "ad7606.h"
 
 #define MAX_SPI_FREQ_HZ		23500000	/* VDRIVE above 4.75 V */
 
+struct spi_bus_data {
+	struct spi_offload *offload;
+	struct spi_offload_trigger *offload_trigger;
+	struct spi_transfer offload_xfer;
+	struct spi_message offload_msg;
+};
+
 static u16 ad7616_spi_rd_wr_cmd(int addr, char is_write_op)
 {
 	/*
@@ -125,19 +141,211 @@ static int ad7606b_sw_mode_config(struct iio_dev *indio_dev)
 				   AD7606_SINGLE_DOUT);
 }
 
+static const struct spi_offload_config ad7606_spi_offload_config = {
+	.capability_flags = SPI_OFFLOAD_CAP_TRIGGER |
+			    SPI_OFFLOAD_CAP_RX_STREAM_DMA,
+};
+
+static int ad7606_spi_offload_buffer_postenable(struct iio_dev *indio_dev)
+{
+	const struct iio_scan_type *scan_type;
+	struct ad7606_state *st = iio_priv(indio_dev);
+	struct spi_bus_data *bus_data = st->bus_data;
+	struct spi_transfer *xfer = &bus_data->offload_xfer;
+	struct spi_device *spi = to_spi_device(st->dev);
+	struct spi_offload_trigger_config config = {
+		.type = SPI_OFFLOAD_TRIGGER_DATA_READY,
+	};
+	int ret;
+
+	scan_type = &indio_dev->channels[0].scan_type;
+
+	xfer->bits_per_word = scan_type->realbits;
+	xfer->offload_flags = SPI_OFFLOAD_XFER_RX_STREAM;
+	/*
+	 * Using SPI offload, storagebits are related to the spi-engine
+	 * hw implementation, can be 16 or 32, so can't be used to compute
+	 * struct spi_transfer.len. Using realbits instead.
+	 */
+	xfer->len = (scan_type->realbits > 16 ? 4 : 2) *
+		    st->chip_info->num_adc_channels;
+
+	spi_message_init_with_transfers(&bus_data->offload_msg, xfer, 1);
+	bus_data->offload_msg.offload = bus_data->offload;
+
+	ret = spi_optimize_message(spi, &bus_data->offload_msg);
+	if (ret) {
+		dev_err(st->dev, "failed to prepare offload, err: %d\n", ret);
+		return ret;
+	}
+
+	ret = spi_offload_trigger_enable(bus_data->offload,
+					 bus_data->offload_trigger,
+					 &config);
+	if (ret)
+		goto err_unoptimize_message;
+
+	ret = ad7606_pwm_set_swing(st);
+	if (ret)
+		goto err_offload_exit_conversion_mode;
+
+	return 0;
+
+err_offload_exit_conversion_mode:
+	spi_offload_trigger_disable(bus_data->offload,
+				    bus_data->offload_trigger);
+
+err_unoptimize_message:
+	spi_unoptimize_message(&bus_data->offload_msg);
+
+	return ret;
+}
+
+static int ad7606_spi_offload_buffer_predisable(struct iio_dev *indio_dev)
+{
+	struct ad7606_state *st = iio_priv(indio_dev);
+	struct spi_bus_data *bus_data = st->bus_data;
+	int ret;
+
+	ret = ad7606_pwm_set_low(st);
+	if (ret)
+		return ret;
+
+	spi_offload_trigger_disable(bus_data->offload,
+				    bus_data->offload_trigger);
+	spi_unoptimize_message(&bus_data->offload_msg);
+
+	return 0;
+}
+
+static const struct iio_buffer_setup_ops ad7606_offload_buffer_setup_ops = {
+	.postenable = ad7606_spi_offload_buffer_postenable,
+	.predisable = ad7606_spi_offload_buffer_predisable,
+};
+
+static bool ad7606_spi_offload_trigger_match(
+				struct spi_offload_trigger *trigger,
+				enum spi_offload_trigger_type type,
+				u64 *args, u32 nargs)
+{
+	if (type != SPI_OFFLOAD_TRIGGER_DATA_READY)
+	       return false;
+
+	/*
+	 * Requires 1 arg:
+	 * args[0] is the trigger event.
+	 */
+	if (nargs != 1 || args[0] != AD7606_TRIGGER_EVENT_BUSY)
+		return false;
+
+	return true;
+}
+
+static int ad7606_spi_offload_trigger_request(
+				struct spi_offload_trigger *trigger,
+				enum spi_offload_trigger_type type,
+				u64 *args, u32 nargs)
+{
+	/* Should already be validated by match, but just in case. */
+	if (nargs != 1)
+		return -EINVAL;
+
+	return 0;
+}
+
+static int ad7606_spi_offload_trigger_validate(
+				struct spi_offload_trigger *trigger,
+				struct spi_offload_trigger_config *config)
+{
+	if (config->type != SPI_OFFLOAD_TRIGGER_DATA_READY)
+		return -EINVAL;
+
+	return 0;
+}
+
+static const struct spi_offload_trigger_ops ad7606_offload_trigger_ops = {
+	.match = ad7606_spi_offload_trigger_match,
+	.request = ad7606_spi_offload_trigger_request,
+	.validate = ad7606_spi_offload_trigger_validate,
+};
+
+static int ad7606_spi_offload_probe(struct device *dev,
+				    struct iio_dev *indio_dev)
+{
+	struct ad7606_state *st = iio_priv(indio_dev);
+	struct spi_device *spi = to_spi_device(dev);
+	struct spi_bus_data *bus_data;
+	struct dma_chan *rx_dma;
+	struct spi_offload_trigger_info trigger_info = {
+		.fwnode = dev_fwnode(dev),
+		.ops = &ad7606_offload_trigger_ops,
+		.priv = st,
+	};
+	int ret;
+
+	bus_data = devm_kzalloc(dev, sizeof(*bus_data), GFP_KERNEL);
+	if (!bus_data)
+		return -ENOMEM;
+	st->bus_data = bus_data;
+
+	bus_data->offload = devm_spi_offload_get(dev, spi,
+						 &ad7606_spi_offload_config);
+	ret = PTR_ERR_OR_ZERO(bus_data->offload);
+	if (ret && ret != -ENODEV)
+		return dev_err_probe(dev, ret, "failed to get SPI offload\n");
+	/* Allow main ad7606_probe function to continue. */
+	if (ret == -ENODEV)
+		return 0;
+
+	ret = devm_spi_offload_trigger_register(dev, &trigger_info);
+	if (ret)
+		return dev_err_probe(dev, ret,
+				     "failed to register offload trigger\n");
+
+	bus_data->offload_trigger = devm_spi_offload_trigger_get(dev,
+		bus_data->offload, SPI_OFFLOAD_TRIGGER_DATA_READY);
+	if (IS_ERR(bus_data->offload_trigger))
+		return dev_err_probe(dev, PTR_ERR(bus_data->offload_trigger),
+				     "failed to get offload trigger\n");
+
+	/* TODO: PWM setup should be ok, done for the backend. PWM mutex ? */
+	rx_dma = devm_spi_offload_rx_stream_request_dma_chan(dev,
+							     bus_data->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 offload RX DMA\n");
+
+	/* Use offload ops. */
+	indio_dev->setup_ops = &ad7606_offload_buffer_setup_ops;
+
+	st->offload_en = true;
+
+	return 0;
+}
+
 static const struct ad7606_bus_ops ad7606_spi_bops = {
+	.offload_config = ad7606_spi_offload_probe,
 	.read_block = ad7606_spi_read_block,
 };
 
 static const struct ad7606_bus_ops ad7607_spi_bops = {
+	.offload_config = ad7606_spi_offload_probe,
 	.read_block = ad7606_spi_read_block14to16,
 };
 
 static const struct ad7606_bus_ops ad7608_spi_bops = {
+	.offload_config = ad7606_spi_offload_probe,
 	.read_block = ad7606_spi_read_block18to32,
 };
 
 static const struct ad7606_bus_ops ad7616_spi_bops = {
+	.offload_config = ad7606_spi_offload_probe,
 	.read_block = ad7606_spi_read_block,
 	.reg_read = ad7606_spi_reg_read,
 	.reg_write = ad7606_spi_reg_write,
@@ -145,6 +353,7 @@ static const struct ad7606_bus_ops ad7616_spi_bops = {
 };
 
 static const struct ad7606_bus_ops ad7606b_spi_bops = {
+	.offload_config = ad7606_spi_offload_probe,
 	.read_block = ad7606_spi_read_block,
 	.reg_read = ad7606_spi_reg_read,
 	.reg_write = ad7606_spi_reg_write,
@@ -153,6 +362,7 @@ static const struct ad7606_bus_ops ad7606b_spi_bops = {
 };
 
 static const struct ad7606_bus_ops ad7606c_18_spi_bops = {
+	.offload_config = ad7606_spi_offload_probe,
 	.read_block = ad7606_spi_read_block18to32,
 	.reg_read = ad7606_spi_reg_read,
 	.reg_write = ad7606_spi_reg_write,
@@ -270,3 +480,4 @@ MODULE_AUTHOR("Michael Hennerich <michael.hennerich@analog.com>");
 MODULE_DESCRIPTION("Analog Devices AD7606 ADC");
 MODULE_LICENSE("GPL v2");
 MODULE_IMPORT_NS("IIO_AD7606");
+MODULE_IMPORT_NS("IIO_DMAENGINE_BUFFER");