spi: axi-spi-engine: add offload support

Merge series from David Lechner <[e-mail]>:

As a recap, here is the background and end goal of this series:

The AXI SPI Engine is a SPI controller that has the ability to record a
series of SPI transactions and then play them back using a hardware
trigger. This allows operations to be performed, repeating many times,
without any CPU intervention. This is needed for achieving high data
rates (millions of samples per second) from ADCs and DACs that are
connected via a SPI bus.

The offload hardware interface consists of a trigger input and a data
output for the RX data. These are connected to other hardware external
to the SPI controller.

To record one or more transactions, commands and TX data are written
to memories in the controller (RX buffer is not used since RX data gets
streamed to an external sink). This sequence of transactions can then be
played back when the trigger input is asserted.

This series includes core SPI support along with the first SPI
controller (AXI SPI Engine) and SPI peripheral (AD7944 ADC) that use
them. This enables capturing analog data at 2 million samples per
second.

The hardware setup looks like this:

+-------------------------------+ +------------------+
| | | |
| SOC/FPGA | | AD7944 ADC |
| +---------------------+ | | |
| | AXI SPI Engine | | | |
| | SPI Bus ============ SPI Bus |
| | | | | |
| | +---------------+ | | | |
| | | Offload 0 | | | +------------------+
| | | RX DATA OUT > > > > |
| | | TRIGGER IN < < < v |
| | +---------------+ | ^ v |
| +---------------------+ ^ v |
| | AXI PWM | ^ v |
| | CH0 > ^ v |
| +---------------------+ v |
| | AXI DMA | v |
| | CH0 < < < |
| +---------------------+ |
| |
+-------------------------------+

Documentation/devicetree/bindings/spi/adi,axi-spi-engine.yaml

···
       - const: s_axi_aclk
       - const: spi_clk
 
+  trigger-sources:
+    description:
+      An array of trigger source phandles for offload instances. The index in
+      the array corresponds to the offload instance number.
+    minItems: 1
+    maxItems: 32
+
+  dmas:
+    description:
+      DMA channels connected to the input or output stream interface of an
+      offload instance.
+    minItems: 1
+    maxItems: 32
+
+  dma-names:
+    items:
+      pattern: "^offload(?:[12]?[0-9]|3[01])-[tr]x$"
+    minItems: 1
+    maxItems: 32
+
 required:
   - compatible
   - reg
···
         interrupts = <0 56 4>;
         clocks = <&clkc 15>, <&clkc 15>;
         clock-names = "s_axi_aclk", "spi_clk";
+
+        trigger-sources = <&trigger_clock>;
+        dmas = <&dma 0>;
+        dma-names = "offload0-rx";
 
         #address-cells = <1>;
         #size-cells = <0>;

Documentation/devicetree/bindings/trigger-source/pwm-trigger.yaml

···
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/trigger-source/pwm-trigger.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Generic trigger source using PWM
+
+description: Remaps a PWM channel as a trigger source.
+
+maintainers:
+  - David Lechner <[e-mail]>
+
+properties:
+  compatible:
+    const: pwm-trigger
+
+  '#trigger-source-cells':
+    const: 0
+
+  pwms:
+    maxItems: 1
+
+required:
+  - compatible
+  - '#trigger-source-cells'
+  - pwms
+
+additionalProperties: false
+
+examples:
+  - |
+    trigger {
+        compatible = "pwm-trigger";
+        #trigger-source-cells = <0>;
+        pwms = <&pwm 0 1000000 0>;
+    };

MAINTAINERS

···
 F:	drivers/mtd/spi-nor/
 F:	include/linux/mtd/spi-nor.h
 
+SPI OFFLOAD
+R:	David Lechner <[e-mail]>
+F:	drivers/spi/spi-offload-trigger-pwm.c
+F:	drivers/spi/spi-offload.c
+F:	include/linux/spi/spi-offload.h
+K:	spi_offload
+
 SPI SUBSYSTEM
 M:	Mark Brown <[e-mail]>
 L:	[e-mail]
···
 W:	https://github.com/srcres258/linux-doc
 T:	git git://github.com/srcres258/linux-doc.git doc-zh-tw
 F:	Documentation/translations/zh_TW/
+
+TRIGGER SOURCE - PWM
+M:	David Lechner <[e-mail]>
+S:	Maintained
+F:	Documentation/devicetree/bindings/trigger-source/pwm-trigger.yaml
 
 TRUSTED SECURITY MODULE (TSM) ATTESTATION REPORTS
 M:	Dan Williams <[e-mail]>

drivers/spi/Kconfig

···
 	  This extension is meant to simplify interaction with SPI memories
 	  by providing a high-level interface to send memory-like commands.
 
+config SPI_OFFLOAD
+	bool
+
 comment "SPI Master Controller Drivers"
 
 config SPI_AIROHA_SNFI
···
 config SPI_AXI_SPI_ENGINE
 	tristate "Analog Devices AXI SPI Engine controller"
 	depends on HAS_IOMEM
+	select SPI_OFFLOAD
 	help
 	  This enables support for the Analog Devices AXI SPI Engine SPI controller.
 	  It is part of the SPI Engine framework that is used in some Analog Devices
···
 
 config SPI_DYNAMIC
 	def_bool ACPI || OF_DYNAMIC || SPI_SLAVE
+
+if SPI_OFFLOAD
+
+comment "SPI Offload triggers"
+
+config SPI_OFFLOAD_TRIGGER_PWM
+	tristate "SPI offload trigger using PWM"
+	depends on PWM
+	help
+	  Generic SPI offload trigger implemented using PWM output.
+
+endif # SPI_OFFLOAD
 
 endif # SPI

drivers/spi/Makefile

···
 obj-$(CONFIG_SPI_MASTER)		+= spi.o
 obj-$(CONFIG_SPI_MEM)			+= spi-mem.o
 obj-$(CONFIG_SPI_MUX)			+= spi-mux.o
+obj-$(CONFIG_SPI_OFFLOAD)		+= spi-offload.o
 obj-$(CONFIG_SPI_SPIDEV)		+= spidev.o
 obj-$(CONFIG_SPI_LOOPBACK_TEST)		+= spi-loopback-test.o
 
···
 # SPI slave protocol handlers
 obj-$(CONFIG_SPI_SLAVE_TIME)		+= spi-slave-time.o
 obj-$(CONFIG_SPI_SLAVE_SYSTEM_CONTROL)	+= spi-slave-system-control.o
+
+# SPI offload triggers
+obj-$(CONFIG_SPI_OFFLOAD_TRIGGER_PWM)	+= spi-offload-trigger-pwm.o

drivers/spi/spi-axi-spi-engine.c

···
 /*
  * SPI-Engine SPI controller driver
  * Copyright 2015 Analog Devices Inc.
+ * Copyright 2024 BayLibre, SAS
  *  Author: Lars-Peter Clausen <[e-mail]>
  */
 
+#include <linux/bitfield.h>
+#include <linux/bitops.h>
 #include <linux/clk.h>
 #include <linux/completion.h>
+#include <linux/dmaengine.h>
 #include <linux/fpga/adi-axi-common.h>
 #include <linux/interrupt.h>
 #include <linux/io.h>
···
 #include <linux/module.h>
 #include <linux/overflow.h>
 #include <linux/platform_device.h>
+#include <linux/spi/offload/provider.h>
 #include <linux/spi/spi.h>
 #include <trace/events/spi.h>
 
+#define SPI_ENGINE_REG_OFFLOAD_MEM_ADDR_WIDTH	0x10
 #define SPI_ENGINE_REG_RESET			0x40
 
 #define SPI_ENGINE_REG_INT_ENABLE		0x80
···
 #define SPI_ENGINE_REG_INT_SOURCE		0x88
 
 #define SPI_ENGINE_REG_SYNC_ID			0xc0
+#define SPI_ENGINE_REG_OFFLOAD_SYNC_ID		0xc4
 
 #define SPI_ENGINE_REG_CMD_FIFO_ROOM		0xd0
 #define SPI_ENGINE_REG_SDO_FIFO_ROOM		0xd4
···
 #define SPI_ENGINE_REG_SDI_DATA_FIFO		0xe8
 #define SPI_ENGINE_REG_SDI_DATA_FIFO_PEEK	0xec
 
+#define SPI_ENGINE_MAX_NUM_OFFLOADS		32
+
+#define SPI_ENGINE_REG_OFFLOAD_CTRL(x)		(0x100 + SPI_ENGINE_MAX_NUM_OFFLOADS * (x))
+#define SPI_ENGINE_REG_OFFLOAD_STATUS(x)	(0x104 + SPI_ENGINE_MAX_NUM_OFFLOADS * (x))
+#define SPI_ENGINE_REG_OFFLOAD_RESET(x)		(0x108 + SPI_ENGINE_MAX_NUM_OFFLOADS * (x))
+#define SPI_ENGINE_REG_OFFLOAD_CMD_FIFO(x)	(0x110 + SPI_ENGINE_MAX_NUM_OFFLOADS * (x))
+#define SPI_ENGINE_REG_OFFLOAD_SDO_FIFO(x)	(0x114 + SPI_ENGINE_MAX_NUM_OFFLOADS * (x))
+
+#define SPI_ENGINE_SPI_OFFLOAD_MEM_WIDTH_SDO	GENMASK(15, 8)
+#define SPI_ENGINE_SPI_OFFLOAD_MEM_WIDTH_CMD	GENMASK(7, 0)
+
 #define SPI_ENGINE_INT_CMD_ALMOST_EMPTY		BIT(0)
 #define SPI_ENGINE_INT_SDO_ALMOST_EMPTY		BIT(1)
 #define SPI_ENGINE_INT_SDI_ALMOST_FULL		BIT(2)
 #define SPI_ENGINE_INT_SYNC			BIT(3)
+#define SPI_ENGINE_INT_OFFLOAD_SYNC		BIT(4)
+
+#define SPI_ENGINE_OFFLOAD_CTRL_ENABLE		BIT(0)
 
 #define SPI_ENGINE_CONFIG_CPHA			BIT(0)
 #define SPI_ENGINE_CONFIG_CPOL			BIT(1)
···
 #define SPI_ENGINE_CMD_CS_INV(flags) \
 	SPI_ENGINE_CMD(SPI_ENGINE_INST_CS_INV, 0, (flags))
 
+/* default sizes - can be changed when SPI Engine firmware is compiled */
+#define SPI_ENGINE_OFFLOAD_CMD_FIFO_SIZE	16
+#define SPI_ENGINE_OFFLOAD_SDO_FIFO_SIZE	16
+
 struct spi_engine_program {
 	unsigned int length;
 	uint16_t instructions[] __counted_by(length);
···
 	uint8_t *rx_buf;
 };
 
+enum {
+	SPI_ENGINE_OFFLOAD_FLAG_ASSIGNED,
+	SPI_ENGINE_OFFLOAD_FLAG_PREPARED,
+};
+
+struct spi_engine_offload {
+	struct spi_engine *spi_engine;
+	unsigned long flags;
+	unsigned int offload_num;
+};
+
 struct spi_engine {
 	struct clk *clk;
 	struct clk *ref_clk;
···
 	unsigned int int_enable;
 	/* shadows hardware CS inversion flag state */
 	u8 cs_inv;
+
+	unsigned int offload_ctrl_mem_size;
+	unsigned int offload_sdo_mem_size;
+	struct spi_offload *offload;
+	u32 offload_caps;
 };
 
 static void spi_engine_program_add_cmd(struct spi_engine_program *p,
···
 		unsigned int n = min(len, 256U);
 		unsigned int flags = 0;
 
-		if (xfer->tx_buf)
+		if (xfer->tx_buf || (xfer->offload_flags & SPI_OFFLOAD_XFER_TX_STREAM))
 			flags |= SPI_ENGINE_TRANSFER_WRITE;
-		if (xfer->rx_buf)
+		if (xfer->rx_buf || (xfer->offload_flags & SPI_OFFLOAD_XFER_RX_STREAM))
 			flags |= SPI_ENGINE_TRANSFER_READ;
 
 		spi_engine_program_add_cmd(p, dry,
···
  *
  * NB: This is separate from spi_engine_compile_message() because the latter
  * is called twice and would otherwise result in double-evaluation.
+ *
+ * Returns 0 on success, -EINVAL on failure.
  */
-static void spi_engine_precompile_message(struct spi_message *msg)
+static int spi_engine_precompile_message(struct spi_message *msg)
 {
 	unsigned int clk_div, max_hz = msg->spi->controller->max_speed_hz;
 	struct spi_transfer *xfer;
 
 	list_for_each_entry(xfer, &msg->transfers, transfer_list) {
+		/* If we have an offload transfer, we can't rx to buffer */
+		if (msg->offload && xfer->rx_buf)
+			return -EINVAL;
+
 		clk_div = DIV_ROUND_UP(max_hz, xfer->speed_hz);
 		xfer->effective_speed_hz = max_hz / min(clk_div, 256U);
 	}
+
+	return 0;
 }
 
 static void spi_engine_compile_message(struct spi_message *msg, bool dry,
···
 	return IRQ_HANDLED;
 }
 
+static int spi_engine_offload_prepare(struct spi_message *msg)
+{
+	struct spi_controller *host = msg->spi->controller;
+	struct spi_engine *spi_engine = spi_controller_get_devdata(host);
+	struct spi_engine_program *p = msg->opt_state;
+	struct spi_engine_offload *priv = msg->offload->priv;
+	struct spi_transfer *xfer;
+	void __iomem *cmd_addr;
+	void __iomem *sdo_addr;
+	size_t tx_word_count = 0;
+	unsigned int i;
+
+	if (p->length > spi_engine->offload_ctrl_mem_size)
+		return -EINVAL;
+
+	/* count total number of tx words in message */
+	list_for_each_entry(xfer, &msg->transfers, transfer_list) {
+		/* no support for reading to rx_buf */
+		if (xfer->rx_buf)
+			return -EINVAL;
+
+		if (!xfer->tx_buf)
+			continue;
+
+		if (xfer->bits_per_word <= 8)
+			tx_word_count += xfer->len;
+		else if (xfer->bits_per_word <= 16)
+			tx_word_count += xfer->len / 2;
+		else
+			tx_word_count += xfer->len / 4;
+	}
+
+	if (tx_word_count && !(spi_engine->offload_caps & SPI_OFFLOAD_CAP_TX_STATIC_DATA))
+		return -EINVAL;
+
+	if (tx_word_count > spi_engine->offload_sdo_mem_size)
+		return -EINVAL;
+
+	/*
+	 * This protects against calling spi_optimize_message() with an offload
+	 * that has already been prepared with a different message.
+	 */
+	if (test_and_set_bit_lock(SPI_ENGINE_OFFLOAD_FLAG_PREPARED, &priv->flags))
+		return -EBUSY;
+
+	cmd_addr = spi_engine->base +
+		   SPI_ENGINE_REG_OFFLOAD_CMD_FIFO(priv->offload_num);
+	sdo_addr = spi_engine->base +
+		   SPI_ENGINE_REG_OFFLOAD_SDO_FIFO(priv->offload_num);
+
+	list_for_each_entry(xfer, &msg->transfers, transfer_list) {
+		if (!xfer->tx_buf)
+			continue;
+
+		if (xfer->bits_per_word <= 8) {
+			const u8 *buf = xfer->tx_buf;
+
+			for (i = 0; i < xfer->len; i++)
+				writel_relaxed(buf[i], sdo_addr);
+		} else if (xfer->bits_per_word <= 16) {
+			const u16 *buf = xfer->tx_buf;
+
+			for (i = 0; i < xfer->len / 2; i++)
+				writel_relaxed(buf[i], sdo_addr);
+		} else {
+			const u32 *buf = xfer->tx_buf;
+
+			for (i = 0; i < xfer->len / 4; i++)
+				writel_relaxed(buf[i], sdo_addr);
+		}
+	}
+
+	for (i = 0; i < p->length; i++)
+		writel_relaxed(p->instructions[i], cmd_addr);
+
+	return 0;
+}
+
+static void spi_engine_offload_unprepare(struct spi_offload *offload)
+{
+	struct spi_engine_offload *priv = offload->priv;
+	struct spi_engine *spi_engine = priv->spi_engine;
+
+	writel_relaxed(1, spi_engine->base +
+			  SPI_ENGINE_REG_OFFLOAD_RESET(priv->offload_num));
+	writel_relaxed(0, spi_engine->base +
+			  SPI_ENGINE_REG_OFFLOAD_RESET(priv->offload_num));
+
+	clear_bit_unlock(SPI_ENGINE_OFFLOAD_FLAG_PREPARED, &priv->flags);
+}
+
 static int spi_engine_optimize_message(struct spi_message *msg)
 {
 	struct spi_engine_program p_dry, *p;
+	int ret;
 
-	spi_engine_precompile_message(msg);
+	ret = spi_engine_precompile_message(msg);
+	if (ret)
+		return ret;
 
 	p_dry.length = 0;
 	spi_engine_compile_message(msg, true, &p_dry);
···
 	spi_engine_compile_message(msg, false, p);
 
 	spi_engine_program_add_cmd(p, false, SPI_ENGINE_CMD_SYNC(
-						AXI_SPI_ENGINE_CUR_MSG_SYNC_ID));
+		msg->offload ? 0 : AXI_SPI_ENGINE_CUR_MSG_SYNC_ID));
 
 	msg->opt_state = p;
+
+	if (msg->offload) {
+		ret = spi_engine_offload_prepare(msg);
+		if (ret) {
+			msg->opt_state = NULL;
+			kfree(p);
+			return ret;
+		}
+	}
 
 	return 0;
 }
 
 static int spi_engine_unoptimize_message(struct spi_message *msg)
 {
+	if (msg->offload)
+		spi_engine_offload_unprepare(msg->offload);
+
 	kfree(msg->opt_state);
 
 	return 0;
+}
+
+static struct spi_offload
+*spi_engine_get_offload(struct spi_device *spi,
+			const struct spi_offload_config *config)
+{
+	struct spi_controller *host = spi->controller;
+	struct spi_engine *spi_engine = spi_controller_get_devdata(host);
+	struct spi_engine_offload *priv;
+
+	if (!spi_engine->offload)
+		return ERR_PTR(-ENODEV);
+
+	if (config->capability_flags & ~spi_engine->offload_caps)
+		return ERR_PTR(-EINVAL);
+
+	priv = spi_engine->offload->priv;
+
+	if (test_and_set_bit_lock(SPI_ENGINE_OFFLOAD_FLAG_ASSIGNED, &priv->flags))
+		return ERR_PTR(-EBUSY);
+
+	return spi_engine->offload;
+}
+
+static void spi_engine_put_offload(struct spi_offload *offload)
+{
+	struct spi_engine_offload *priv = offload->priv;
+
+	clear_bit_unlock(SPI_ENGINE_OFFLOAD_FLAG_ASSIGNED, &priv->flags);
 }
 
 static int spi_engine_setup(struct spi_device *device)
···
 	struct spi_engine_program *p = msg->opt_state;
 	unsigned int int_enable = 0;
 	unsigned long flags;
+
+	if (msg->offload) {
+		dev_err(&host->dev, "Single transfer offload not supported\n");
+		msg->status = -EOPNOTSUPP;
+		goto out;
+	}
 
 	/* reinitialize message state for this transfer */
 	memset(st, 0, sizeof(*st));
···
 			trace_spi_transfer_stop(msg, xfer);
 	}
 
+out:
 	spi_finalize_current_message(host);
 
 	return msg->status;
 }
+
+static int spi_engine_trigger_enable(struct spi_offload *offload)
+{
+	struct spi_engine_offload *priv = offload->priv;
+	struct spi_engine *spi_engine = priv->spi_engine;
+	unsigned int reg;
+
+	reg = readl_relaxed(spi_engine->base +
+			    SPI_ENGINE_REG_OFFLOAD_CTRL(priv->offload_num));
+	reg |= SPI_ENGINE_OFFLOAD_CTRL_ENABLE;
+	writel_relaxed(reg, spi_engine->base +
+			    SPI_ENGINE_REG_OFFLOAD_CTRL(priv->offload_num));
+	return 0;
+}
+
+static void spi_engine_trigger_disable(struct spi_offload *offload)
+{
+	struct spi_engine_offload *priv = offload->priv;
+	struct spi_engine *spi_engine = priv->spi_engine;
+	unsigned int reg;
+
+	reg = readl_relaxed(spi_engine->base +
+			    SPI_ENGINE_REG_OFFLOAD_CTRL(priv->offload_num));
+	reg &= ~SPI_ENGINE_OFFLOAD_CTRL_ENABLE;
+	writel_relaxed(reg, spi_engine->base +
+			    SPI_ENGINE_REG_OFFLOAD_CTRL(priv->offload_num));
+}
+
+static struct dma_chan
+*spi_engine_tx_stream_request_dma_chan(struct spi_offload *offload)
+{
+	struct spi_engine_offload *priv = offload->priv;
+	char name[16];
+
+	snprintf(name, sizeof(name), "offload%u-tx", priv->offload_num);
+
+	return dma_request_chan(offload->provider_dev, name);
+}
+
+static struct dma_chan
+*spi_engine_rx_stream_request_dma_chan(struct spi_offload *offload)
+{
+	struct spi_engine_offload *priv = offload->priv;
+	char name[16];
+
+	snprintf(name, sizeof(name), "offload%u-rx", priv->offload_num);
+
+	return dma_request_chan(offload->provider_dev, name);
+}
+
+static const struct spi_offload_ops spi_engine_offload_ops = {
+	.trigger_enable = spi_engine_trigger_enable,
+	.trigger_disable = spi_engine_trigger_disable,
+	.tx_stream_request_dma_chan = spi_engine_tx_stream_request_dma_chan,
+	.rx_stream_request_dma_chan = spi_engine_rx_stream_request_dma_chan,
+};
 
 static void spi_engine_release_hw(void *p)
 {
···
 	struct spi_engine *spi_engine;
 	struct spi_controller *host;
 	unsigned int version;
-	int irq;
-	int ret;
+	int irq, ret;
 
 	irq = platform_get_irq(pdev, 0);
 	if (irq < 0)
···
 
 	spin_lock_init(&spi_engine->lock);
 	init_completion(&spi_engine->msg_complete);
+
+	/*
+	 * REVISIT: for now, all SPI Engines only have one offload. In the
+	 * future, this should be read from a memory mapped register to
+	 * determine the number of offloads enabled at HDL compile time. For
+	 * now, we can tell if an offload is present if there is a trigger
+	 * source wired up to it.
+	 */
+	if (device_property_present(&pdev->dev, "trigger-sources")) {
+		struct spi_engine_offload *priv;
+
+		spi_engine->offload =
+			devm_spi_offload_alloc(&pdev->dev,
+					       sizeof(struct spi_engine_offload));
+		if (IS_ERR(spi_engine->offload))
+			return PTR_ERR(spi_engine->offload);
+
+		priv = spi_engine->offload->priv;
+		priv->spi_engine = spi_engine;
+		priv->offload_num = 0;
+
+		spi_engine->offload->ops = &spi_engine_offload_ops;
+		spi_engine->offload_caps = SPI_OFFLOAD_CAP_TRIGGER;
+
+		if (device_property_match_string(&pdev->dev, "dma-names", "offload0-rx") >= 0) {
+			spi_engine->offload_caps |= SPI_OFFLOAD_CAP_RX_STREAM_DMA;
+			spi_engine->offload->xfer_flags |= SPI_OFFLOAD_XFER_RX_STREAM;
+		}
+
+		if (device_property_match_string(&pdev->dev, "dma-names", "offload0-tx") >= 0) {
+			spi_engine->offload_caps |= SPI_OFFLOAD_CAP_TX_STREAM_DMA;
+			spi_engine->offload->xfer_flags |= SPI_OFFLOAD_XFER_TX_STREAM;
+		} else {
+			/*
+			 * HDL compile option to enable TX DMA stream also disables
+			 * the SDO memory, so can't do both at the same time.
+			 */
+			spi_engine->offload_caps |= SPI_OFFLOAD_CAP_TX_STATIC_DATA;
+		}
+	}
 
 	spi_engine->clk = devm_clk_get_enabled(&pdev->dev, "s_axi_aclk");
 	if (IS_ERR(spi_engine->clk))
···
 			ADI_AXI_PCORE_VER_MINOR(version),
 			ADI_AXI_PCORE_VER_PATCH(version));
 		return -ENODEV;
+	}
+
+	if (ADI_AXI_PCORE_VER_MINOR(version) >= 1) {
+		unsigned int sizes = readl(spi_engine->base +
+				SPI_ENGINE_REG_OFFLOAD_MEM_ADDR_WIDTH);
+
+		spi_engine->offload_ctrl_mem_size = 1 <<
+			FIELD_GET(SPI_ENGINE_SPI_OFFLOAD_MEM_WIDTH_CMD, sizes);
+		spi_engine->offload_sdo_mem_size = 1 <<
+			FIELD_GET(SPI_ENGINE_SPI_OFFLOAD_MEM_WIDTH_SDO, sizes);
+	} else {
+		spi_engine->offload_ctrl_mem_size = SPI_ENGINE_OFFLOAD_CMD_FIFO_SIZE;
+		spi_engine->offload_sdo_mem_size = SPI_ENGINE_OFFLOAD_SDO_FIFO_SIZE;
 	}
 
 	writel_relaxed(0x00, spi_engine->base + SPI_ENGINE_REG_RESET);
···
 	host->transfer_one_message = spi_engine_transfer_one_message;
 	host->optimize_message = spi_engine_optimize_message;
 	host->unoptimize_message = spi_engine_unoptimize_message;
+	host->get_offload = spi_engine_get_offload;
+	host->put_offload = spi_engine_put_offload;
 	host->num_chipselect = 8;
 
 	/* Some features depend of the IP core version. */

drivers/spi/spi-offload-trigger-pwm.c

···
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2024 Analog Devices Inc.
+ * Copyright (C) 2024 BayLibre, SAS
+ *
+ * Generic PWM trigger for SPI offload.
+ */
+
+#include <linux/platform_device.h>
+#include <linux/pwm.h>
+#include <linux/mod_devicetable.h>
+#include <linux/spi/offload/provider.h>
+#include <linux/types.h>
+
+struct spi_offload_trigger_pwm_state {
+	struct device *dev;
+	struct pwm_device *pwm;
+};
+
+static bool spi_offload_trigger_pwm_match(struct spi_offload_trigger *trigger,
+					  enum spi_offload_trigger_type type,
+					  u64 *args, u32 nargs)
+{
+	if (nargs)
+		return false;
+
+	return type == SPI_OFFLOAD_TRIGGER_PERIODIC;
+}
+
+static int spi_offload_trigger_pwm_validate(struct spi_offload_trigger *trigger,
+					    struct spi_offload_trigger_config *config)
+{
+	struct spi_offload_trigger_pwm_state *st = spi_offload_trigger_get_priv(trigger);
+	struct spi_offload_trigger_periodic *periodic = &config->periodic;
+	struct pwm_waveform wf = { };
+	int ret;
+
+	if (config->type != SPI_OFFLOAD_TRIGGER_PERIODIC)
+		return -EINVAL;
+
+	if (!periodic->frequency_hz)
+		return -EINVAL;
+
+	wf.period_length_ns = DIV_ROUND_UP_ULL(NSEC_PER_SEC, periodic->frequency_hz);
+	/* REVISIT: 50% duty-cycle for now - may add config parameter later */
+	wf.duty_length_ns = wf.period_length_ns / 2;
+
+	ret = pwm_round_waveform_might_sleep(st->pwm, &wf);
+	if (ret < 0)
+		return ret;
+
+	periodic->frequency_hz = DIV_ROUND_UP_ULL(NSEC_PER_SEC, wf.period_length_ns);
+
+	return 0;
+}
+
+static int spi_offload_trigger_pwm_enable(struct spi_offload_trigger *trigger,
+					  struct spi_offload_trigger_config *config)
+{
+	struct spi_offload_trigger_pwm_state *st = spi_offload_trigger_get_priv(trigger);
+	struct spi_offload_trigger_periodic *periodic = &config->periodic;
+	struct pwm_waveform wf = { };
+
+	if (config->type != SPI_OFFLOAD_TRIGGER_PERIODIC)
+		return -EINVAL;
+
+	if (!periodic->frequency_hz)
+		return -EINVAL;
+
+	wf.period_length_ns = DIV_ROUND_UP_ULL(NSEC_PER_SEC, periodic->frequency_hz);
+	/* REVISIT: 50% duty-cycle for now - may add config parameter later */
+	wf.duty_length_ns = wf.period_length_ns / 2;
+
+	return pwm_set_waveform_might_sleep(st->pwm, &wf, false);
+}
+
+static void spi_offload_trigger_pwm_disable(struct spi_offload_trigger *trigger)
+{
+	struct spi_offload_trigger_pwm_state *st = spi_offload_trigger_get_priv(trigger);
+	struct pwm_waveform wf;
+	int ret;
+
+	ret = pwm_get_waveform_might_sleep(st->pwm, &wf);
+	if (ret < 0) {
+		dev_err(st->dev, "failed to get waveform: %d\n", ret);
+		return;
+	}
+
+	wf.duty_length_ns = 0;
+
+	ret = pwm_set_waveform_might_sleep(st->pwm, &wf, false);
+	if (ret < 0)
+		dev_err(st->dev, "failed to disable PWM: %d\n", ret);
+}
+
+static const struct spi_offload_trigger_ops spi_offload_trigger_pwm_ops = {
+	.match = spi_offload_trigger_pwm_match,
+	.validate = spi_offload_trigger_pwm_validate,
+	.enable = spi_offload_trigger_pwm_enable,
+	.disable = spi_offload_trigger_pwm_disable,
+};
+
+static void spi_offload_trigger_pwm_release(void *data)
+{
+	pwm_disable(data);
+}
+
+static int spi_offload_trigger_pwm_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct spi_offload_trigger_info info = {
+		.fwnode = dev_fwnode(dev),
+		.ops = &spi_offload_trigger_pwm_ops,
+	};
+	struct spi_offload_trigger_pwm_state *st;
+	struct pwm_state state;
+	int ret;
+
+	st = devm_kzalloc(dev, sizeof(*st), GFP_KERNEL);
+	if (!st)
+		return -ENOMEM;
+
+	info.priv = st;
+	st->dev = dev;
+
+	st->pwm = devm_pwm_get(dev, NULL);
+	if (IS_ERR(st->pwm))
+		return dev_err_probe(dev, PTR_ERR(st->pwm), "failed to get PWM\n");
+
+	/* init with duty_cycle = 0, output enabled to ensure trigger off */
+	pwm_init_state(st->pwm, &state);
+	state.enabled = true;
+
+	ret = pwm_apply_might_sleep(st->pwm, &state);
+	if (ret < 0)
+		return dev_err_probe(dev, ret, "failed to apply PWM state\n");
+
+	ret = devm_add_action_or_reset(dev, spi_offload_trigger_pwm_release, st->pwm);
+	if (ret)
+		return ret;
+
+	return devm_spi_offload_trigger_register(dev, &info);
+}
+
+static const struct of_device_id spi_offload_trigger_pwm_of_match_table[] = {
+	{ .compatible = "pwm-trigger" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, spi_offload_trigger_pwm_of_match_table);
+
+static struct platform_driver spi_offload_trigger_pwm_driver = {
+	.driver = {
+		.name = "pwm-trigger",
+		.of_match_table = spi_offload_trigger_pwm_of_match_table,
+	},
+	.probe = spi_offload_trigger_pwm_probe,
+};
+module_platform_driver(spi_offload_trigger_pwm_driver);
+
+MODULE_AUTHOR("David Lechner <[e-mail]>");
+MODULE_DESCRIPTION("Generic PWM trigger");
+MODULE_LICENSE("GPL");

drivers/spi/spi-offload.c

···
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2024 Analog Devices Inc.
+ * Copyright (C) 2024 BayLibre, SAS
+ */
+
+/*
+ * SPI Offloading support.
+ *
+ * Some SPI controllers support offloading of SPI transfers. Essentially, this
+ * is the ability for a SPI controller to perform SPI transfers with minimal
+ * or even no CPU intervention, e.g. via a specialized SPI controller with a
+ * hardware trigger or via a conventional SPI controller using a non-Linux MCU
+ * processor core to offload the work.
+ */
+
+#define DEFAULT_SYMBOL_NAMESPACE "SPI_OFFLOAD"
+
+#include <linux/cleanup.h>
+#include <linux/device.h>
+#include <linux/dmaengine.h>
+#include <linux/export.h>
+#include <linux/kref.h>
+#include <linux/list.h>
+#include <linux/mutex.h>
+#include <linux/of.h>
+#include <linux/property.h>
+#include <linux/spi/offload/consumer.h>
+#include <linux/spi/offload/provider.h>
+#include <linux/spi/offload/types.h>
+#include <linux/spi/spi.h>
+#include <linux/types.h>
+
+struct spi_controller_and_offload {
+	struct spi_controller *controller;
+	struct spi_offload *offload;
+};
+
+struct spi_offload_trigger {
+	struct list_head list;
+	struct kref ref;
+	struct fwnode_handle *fwnode;
+	/* synchronizes calling ops and driver registration */
+	struct mutex lock;
+	/*
+	 * If the provider goes away while the consumer still has a reference,
+	 * ops and priv will be set to NULL and all calls will fail with -ENODEV.
+	 */
+	const struct spi_offload_trigger_ops *ops;
+	void *priv;
+};
+
+static LIST_HEAD(spi_offload_triggers);
+static DEFINE_MUTEX(spi_offload_triggers_lock);
+
+/**
+ * devm_spi_offload_alloc() - Allocate offload instance
+ * @dev: Device for devm purposes and assigned to &struct spi_offload.provider_dev
+ * @priv_size: Size of private data to allocate
+ *
+ * Offload providers should use this to allocate offload instances.
+ *
+ * Return: Pointer to new offload instance or error on failure.
+ */
+struct spi_offload *devm_spi_offload_alloc(struct device *dev,
+					   size_t priv_size)
+{
+	struct spi_offload *offload;
+	void *priv;
+
+	offload = devm_kzalloc(dev, sizeof(*offload), GFP_KERNEL);
+	if (!offload)
+		return ERR_PTR(-ENOMEM);
+
+	priv = devm_kzalloc(dev, priv_size, GFP_KERNEL);
+	if (!priv)
+		return ERR_PTR(-ENOMEM);
+
+	offload->provider_dev = dev;
+	offload->priv = priv;
+
+	return offload;
+}
+EXPORT_SYMBOL_GPL(devm_spi_offload_alloc);
+
+static void spi_offload_put(void *data)
+{
+	struct spi_controller_and_offload *resource = data;
+
+	resource->controller->put_offload(resource->offload);
+	kfree(resource);
+}
+
+/**
+ * devm_spi_offload_get() - Get an offload instance
+ * @dev: Device for devm purposes
+ * @spi: SPI device to use for the transfers
+ * @config: Offload configuration
+ *
+ * Peripheral drivers call this function to get an offload instance that meets
+ * the requirements specified in @config. If no suitable offload instance is
+ * available, -ENODEV is returned.
+ *
+ * Return: Offload instance or error on failure.
+ */
+struct spi_offload *devm_spi_offload_get(struct device *dev,
+					 struct spi_device *spi,
+					 const struct spi_offload_config *config)
+{
+	struct spi_controller_and_offload *resource;
+	int ret;
+
+	if (!spi || !config)
+		return ERR_PTR(-EINVAL);
+
+	if (!spi->controller->get_offload)
+		return ERR_PTR(-ENODEV);
+
+	resource = kzalloc(sizeof(*resource), GFP_KERNEL);
+	if (!resource)
+		return ERR_PTR(-ENOMEM);
+
+	resource->controller = spi->controller;
+	resource->offload = spi->controller->get_offload(spi, config);
+	if (IS_ERR(resource->offload)) {
+		kfree(resource);
+		return resource->offload;
+	}
+
+	ret = devm_add_action_or_reset(dev, spi_offload_put, resource);
+	if (ret)
+		return ERR_PTR(ret);
+
+	return resource->offload;
+}
+EXPORT_SYMBOL_GPL(devm_spi_offload_get);
+
+static void spi_offload_trigger_free(struct kref *ref)
+{
+	struct spi_offload_trigger *trigger =
+		container_of(ref, struct spi_offload_trigger, ref);
+
+	mutex_destroy(&trigger->lock);
+	fwnode_handle_put(trigger->fwnode);
+	kfree(trigger);
+}
+
+static void spi_offload_trigger_put(void *data)
+{
+	struct spi_offload_trigger *trigger = data;
+
+	scoped_guard(mutex, &trigger->lock)
+		if (trigger->ops && trigger->ops->release)
+			trigger->ops->release(trigger);
+
+	kref_put(&trigger->ref, spi_offload_trigger_free);
+}
+
+static struct spi_offload_trigger
+*spi_offload_trigger_get(enum spi_offload_trigger_type type,
+			 struct fwnode_reference_args *args)
+{
+	struct spi_offload_trigger *trigger;
+	bool match = false;
+	int ret;
+
+	guard(mutex)(&spi_offload_triggers_lock);
+
+	list_for_each_entry(trigger, &spi_offload_triggers, list) {
+		if (trigger->fwnode != args->fwnode)
+			continue;
+
+		match = trigger->ops->match(trigger, type, args->args, args->nargs);
+		if (match)
+			break;
+	}
+
+	if (!match)
+		return ERR_PTR(-EPROBE_DEFER);
+
+	guard(mutex)(&trigger->lock);
+
+	if (!trigger->ops)
+		return ERR_PTR(-ENODEV);
+
+	if (trigger->ops->request) {
+		ret = trigger->ops->request(trigger, type, args->args, args->nargs);
+		if (ret)
+			return ERR_PTR(ret);
+	}
+
+	kref_get(&trigger->ref);
+
+	return trigger;
+}
+
+/**
+ * devm_spi_offload_trigger_get() - Get an offload trigger instance
+ * @dev: Device for devm purposes.
+ * @offload: Offload instance connected to a trigger.
+ * @type: Trigger type to get.
+ *
+ * Return: Offload trigger instance or error on failure.
+ */
+struct spi_offload_trigger
+*devm_spi_offload_trigger_get(struct device *dev,
+			      struct spi_offload *offload,
+			      enum spi_offload_trigger_type type)
+{
+	struct spi_offload_trigger *trigger;
+	struct fwnode_reference_args args;
+	int ret;
+
+	ret = fwnode_property_get_reference_args(dev_fwnode(offload->provider_dev),
+						 "trigger-sources",
+						 "#trigger-source-cells", 0, 0,
+						 &args);
+	if (ret)
+		return ERR_PTR(ret);
+
+	trigger = spi_offload_trigger_get(type, &args);
+	fwnode_handle_put(args.fwnode);
+	if (IS_ERR(trigger))
+		return trigger;
+
+	ret = devm_add_action_or_reset(dev, spi_offload_trigger_put, trigger);
+	if (ret)
+		return ERR_PTR(ret);
+
+	return trigger;
+}
+EXPORT_SYMBOL_GPL(devm_spi_offload_trigger_get);
+
+/**
+ * spi_offload_trigger_validate - Validate the requested trigger
+ * @trigger: Offload trigger instance
+ * @config: Trigger config to validate
+ *
+ * On success, @config may be modifed to reflect what the hardware can do.
+ * For example, the frequency of a periodic trigger may be adjusted to the
+ * nearest supported value.
+ *
+ * Callers will likely need to do additional validation of the modified trigger
+ * parameters.
+ *
+ * Return: 0 on success, negative error code on failure.
+ */
+int spi_offload_trigger_validate(struct spi_offload_trigger *trigger,
+				 struct spi_offload_trigger_config *config)
+{
+	guard(mutex)(&trigger->lock);
+
+	if (!trigger->ops)
+		return -ENODEV;
+
+	if (!trigger->ops->validate)
+		return -EOPNOTSUPP;
+
+	return trigger->ops->validate(trigger, config);
+}
+EXPORT_SYMBOL_GPL(spi_offload_trigger_validate);
+
+/**
+ * spi_offload_trigger_enable - enables trigger for offload
+ * @offload: Offload instance
+ * @trigger: Offload trigger instance
+ * @config: Trigger config to validate
+ *
+ * There must be a prepared offload instance with the specified ID (i.e.
+ * spi_optimize_message() was called with the same offload assigned to the
+ * message). This will also reserve the bus for exclusive use by the offload
+ * instance until the trigger is disabled. Any other attempts to send a
+ * transfer or lock the bus will fail with -EBUSY during this time.
+ *
+ * Calls must be balanced with spi_offload_trigger_disable().
+ *
+ * Context: can sleep
+ * Return: 0 on success, else a negative error code.
+ */
+int spi_offload_trigger_enable(struct spi_offload *offload,
+			       struct spi_offload_trigger *trigger,
+			       struct spi_offload_trigger_config *config)
+{
+	int ret;
+
+	guard(mutex)(&trigger->lock);
+
+	if (!trigger->ops)
+		return -ENODEV;
+
+	if (offload->ops && offload->ops->trigger_enable) {
+		ret = offload->ops->trigger_enable(offload);
+		if (ret)
+			return ret;
+	}
+
+	if (trigger->ops->enable) {
+		ret = trigger->ops->enable(trigger, config);
+		if (ret) {
+			if (offload->ops->trigger_disable)
+				offload->ops->trigger_disable(offload);
+			return ret;
+		}
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(spi_offload_trigger_enable);
+
+/**
+ * spi_offload_trigger_disable - disables hardware trigger for offload
+ * @offload: Offload instance
+ * @trigger: Offload trigger instance
+ *
+ * Disables the hardware trigger for the offload instance with the specified ID
+ * and releases the bus for use by other clients.
+ *
+ * Context: can sleep
+ */
+void spi_offload_trigger_disable(struct spi_offload *offload,
+				 struct spi_offload_trigger *trigger)
+{
+	if (offload->ops && offload->ops->trigger_disable)
+		offload->ops->trigger_disable(offload);
+
+	guard(mutex)(&trigger->lock);
+
+	if (!trigger->ops)
+		return;
+
+	if (trigger->ops->disable)
+		trigger->ops->disable(trigger);
+}
+EXPORT_SYMBOL_GPL(spi_offload_trigger_disable);
+
+static void spi_offload_release_dma_chan(void *chan)
+{
+	dma_release_channel(chan);
+}
+
+/**
+ * devm_spi_offload_tx_stream_request_dma_chan - Get the DMA channel info for the TX stream
+ * @dev: Device for devm purposes.
+ * @offload: Offload instance
+ *
+ * This is the DMA channel that will provide data to transfers that use the
+ * %SPI_OFFLOAD_XFER_TX_STREAM offload flag.
+ *
+ * Return: Pointer to DMA channel info, or negative error code
+ */
+struct dma_chan
+*devm_spi_offload_tx_stream_request_dma_chan(struct device *dev,
+					     struct spi_offload *offload)
+{
+	struct dma_chan *chan;
+	int ret;
+
+	if (!offload->ops || !offload->ops->tx_stream_request_dma_chan)
+		return ERR_PTR(-EOPNOTSUPP);
+
+	chan = offload->ops->tx_stream_request_dma_chan(offload);
+	if (IS_ERR(chan))
+		return chan;
+
+	ret = devm_add_action_or_reset(dev, spi_offload_release_dma_chan, chan);
+	if (ret)
+		return ERR_PTR(ret);
+
+	return chan;
+}
+EXPORT_SYMBOL_GPL(devm_spi_offload_tx_stream_request_dma_chan);
+
+/**
+ * devm_spi_offload_rx_stream_request_dma_chan - Get the DMA channel info for the RX stream
+ * @dev: Device for devm purposes.
+ * @offload: Offload instance
+ *
+ * This is the DMA channel that will receive data from transfers that use the
+ * %SPI_OFFLOAD_XFER_RX_STREAM offload flag.
+ *
+ * Return: Pointer to DMA channel info, or negative error code
+ */
+struct dma_chan
+*devm_spi_offload_rx_stream_request_dma_chan(struct device *dev,
+					     struct spi_offload *offload)
+{
+	struct dma_chan *chan;
+	int ret;
+
+	if (!offload->ops || !offload->ops->rx_stream_request_dma_chan)
+		return ERR_PTR(-EOPNOTSUPP);
+
+	chan = offload->ops->rx_stream_request_dma_chan(offload);
+	if (IS_ERR(chan))
+		return chan;
+
+	ret = devm_add_action_or_reset(dev, spi_offload_release_dma_chan, chan);
+	if (ret)
+		return ERR_PTR(ret);
+
+	return chan;
+}
+EXPORT_SYMBOL_GPL(devm_spi_offload_rx_stream_request_dma_chan);
+
+/* Triggers providers */
+
+static void spi_offload_trigger_unregister(void *data)
+{
+	struct spi_offload_trigger *trigger = data;
+
+	scoped_guard(mutex, &spi_offload_triggers_lock)
+		list_del(&trigger->list);
+
+	scoped_guard(mutex, &trigger->lock) {
+		trigger->priv = NULL;
+		trigger->ops = NULL;
+	}
+
+	kref_put(&trigger->ref, spi_offload_trigger_free);
+}
+
+/**
+ * devm_spi_offload_trigger_register() - Allocate and register an offload trigger
+ * @dev: Device for devm purposes.
+ * @info: Provider-specific trigger info.
+ *
+ * Return: 0 on success, else a negative error code.
+ */
+int devm_spi_offload_trigger_register(struct device *dev,
+				      struct spi_offload_trigger_info *info)
+{
+	struct spi_offload_trigger *trigger;
+
+	if (!info->fwnode || !info->ops)
+		return -EINVAL;
+
+	trigger = kzalloc(sizeof(*trigger), GFP_KERNEL);
+	if (!trigger)
+		return -ENOMEM;
+
+	kref_init(&trigger->ref);
+	mutex_init(&trigger->lock);
+	trigger->fwnode = fwnode_handle_get(info->fwnode);
+	trigger->ops = info->ops;
+	trigger->priv = info->priv;
+
+	scoped_guard(mutex, &spi_offload_triggers_lock)
+		list_add_tail(&trigger->list, &spi_offload_triggers);
+
+	return devm_add_action_or_reset(dev, spi_offload_trigger_unregister, trigger);
+}
+EXPORT_SYMBOL_GPL(devm_spi_offload_trigger_register);
+
+/**
+ * spi_offload_trigger_get_priv() - Get the private data for the trigger
+ *
+ * @trigger: Offload trigger instance.
+ *
+ * Return: Private data for the trigger.
+ */
+void *spi_offload_trigger_get_priv(struct spi_offload_trigger *trigger)
+{
+	return trigger->priv;
+}
+EXPORT_SYMBOL_GPL(spi_offload_trigger_get_priv);

drivers/spi/spi.c

···
 #include <linux/ptp_clock_kernel.h>
 #include <linux/sched/rt.h>
 #include <linux/slab.h>
+#include <linux/spi/offload/types.h>
 #include <linux/spi/spi.h>
 #include <linux/spi/spi-mem.h>
 #include <uapi/linux/sched/types.h>
···
 
 		if (_spi_xfer_word_delay_update(xfer, spi))
 			return -EINVAL;
+
+		/* Make sure controller supports required offload features. */
+		if (xfer->offload_flags) {
+			if (!message->offload)
+				return -EINVAL;
+
+			if (xfer->offload_flags & ~message->offload->xfer_flags)
+				return -EINVAL;
+		}
 	}
 
 	message->status = -EINPROGRESS;

include/linux/spi/offload/consumer.h

···
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2024 Analog Devices Inc.
+ * Copyright (C) 2024 BayLibre, SAS
+ */
+
+#ifndef __LINUX_SPI_OFFLOAD_CONSUMER_H
+#define __LINUX_SPI_OFFLOAD_CONSUMER_H
+
+#include <linux/module.h>
+#include <linux/spi/offload/types.h>
+#include <linux/types.h>
+
+MODULE_IMPORT_NS("SPI_OFFLOAD");
+
+struct device;
+struct spi_device;
+
+struct spi_offload *devm_spi_offload_get(struct device *dev, struct spi_device *spi,
+					 const struct spi_offload_config *config);
+
+struct spi_offload_trigger
+*devm_spi_offload_trigger_get(struct device *dev,
+			      struct spi_offload *offload,
+			      enum spi_offload_trigger_type type);
+int spi_offload_trigger_validate(struct spi_offload_trigger *trigger,
+				 struct spi_offload_trigger_config *config);
+int spi_offload_trigger_enable(struct spi_offload *offload,
+			       struct spi_offload_trigger *trigger,
+			       struct spi_offload_trigger_config *config);
+void spi_offload_trigger_disable(struct spi_offload *offload,
+				 struct spi_offload_trigger *trigger);
+
+struct dma_chan *devm_spi_offload_tx_stream_request_dma_chan(struct device *dev,
+							     struct spi_offload *offload);
+struct dma_chan *devm_spi_offload_rx_stream_request_dma_chan(struct device *dev,
+							     struct spi_offload *offload);
+
+#endif /* __LINUX_SPI_OFFLOAD_CONSUMER_H */

include/linux/spi/offload/provider.h

···
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2024 Analog Devices Inc.
+ * Copyright (C) 2024 BayLibre, SAS
+ */
+
+#ifndef __LINUX_SPI_OFFLOAD_PROVIDER_H
+#define __LINUX_SPI_OFFLOAD_PROVIDER_H
+
+#include <linux/module.h>
+#include <linux/spi/offload/types.h>
+#include <linux/types.h>
+
+MODULE_IMPORT_NS("SPI_OFFLOAD");
+
+struct device;
+struct spi_offload_trigger;
+
+struct spi_offload *devm_spi_offload_alloc(struct device *dev, size_t priv_size);
+
+struct spi_offload_trigger_ops {
+	bool (*match)(struct spi_offload_trigger *trigger,
+		      enum spi_offload_trigger_type type, u64 *args, u32 nargs);
+	int (*request)(struct spi_offload_trigger *trigger,
+		       enum spi_offload_trigger_type type, u64 *args, u32 nargs);
+	void (*release)(struct spi_offload_trigger *trigger);
+	int (*validate)(struct spi_offload_trigger *trigger,
+			struct spi_offload_trigger_config *config);
+	int (*enable)(struct spi_offload_trigger *trigger,
+		      struct spi_offload_trigger_config *config);
+	void (*disable)(struct spi_offload_trigger *trigger);
+};
+
+struct spi_offload_trigger_info {
+	/** @fwnode: Provider fwnode, used to match to consumer. */
+	struct fwnode_handle *fwnode;
+	/** @ops: Provider-specific callbacks. */
+	const struct spi_offload_trigger_ops *ops;
+	/** Provider-specific state to be used in callbacks. */
+	void *priv;
+};
+
+int devm_spi_offload_trigger_register(struct device *dev,
+				      struct spi_offload_trigger_info *info);
+void *spi_offload_trigger_get_priv(struct spi_offload_trigger *trigger);
+
+#endif /* __LINUX_SPI_OFFLOAD_PROVIDER_H */

include/linux/spi/offload/types.h

···
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2024 Analog Devices Inc.
+ * Copyright (C) 2024 BayLibre, SAS
+ */
+
+#ifndef __LINUX_SPI_OFFLOAD_TYPES_H
+#define __LINUX_SPI_OFFLOAD_TYPES_H
+
+#include <linux/types.h>
+
+struct device;
+
+/* This is write xfer but TX uses external data stream rather than tx_buf. */
+#define SPI_OFFLOAD_XFER_TX_STREAM	BIT(0)
+/* This is read xfer but RX uses external data stream rather than rx_buf. */
+#define SPI_OFFLOAD_XFER_RX_STREAM	BIT(1)
+
+/* Offload can be triggered by external hardware event. */
+#define SPI_OFFLOAD_CAP_TRIGGER			BIT(0)
+/* Offload can record and then play back TX data when triggered. */
+#define SPI_OFFLOAD_CAP_TX_STATIC_DATA		BIT(1)
+/* Offload can get TX data from an external stream source. */
+#define SPI_OFFLOAD_CAP_TX_STREAM_DMA		BIT(2)
+/* Offload can send RX data to an external stream sink. */
+#define SPI_OFFLOAD_CAP_RX_STREAM_DMA		BIT(3)
+
+/**
+ * struct spi_offload_config - offload configuration
+ *
+ * This is used to request an offload with specific configuration.
+ */
+struct spi_offload_config {
+	/** @capability_flags: required capabilities. See %SPI_OFFLOAD_CAP_* */
+	u32 capability_flags;
+};
+
+/**
+ * struct spi_offload - offload instance
+ */
+struct spi_offload {
+	/** @provider_dev: for get/put reference counting */
+	struct device *provider_dev;
+	/** @priv: provider driver private data */
+	void *priv;
+	/** @ops: callbacks for offload support */
+	const struct spi_offload_ops *ops;
+	/** @xfer_flags: %SPI_OFFLOAD_XFER_* flags supported by provider */
+	u32 xfer_flags;
+};
+
+enum spi_offload_trigger_type {
+	/* Indication from SPI peripheral that data is read to read. */
+	SPI_OFFLOAD_TRIGGER_DATA_READY,
+	/* Trigger comes from a periodic source such as a clock. */
+	SPI_OFFLOAD_TRIGGER_PERIODIC,
+};
+
+struct spi_offload_trigger_periodic {
+	u64 frequency_hz;
+};
+
+struct spi_offload_trigger_config {
+	/** @type: type discriminator for union */
+	enum spi_offload_trigger_type type;
+	union {
+		struct spi_offload_trigger_periodic periodic;
+	};
+};
+
+/**
+ * struct spi_offload_ops - callbacks implemented by offload providers
+ */
+struct spi_offload_ops {
+	/**
+	 * @trigger_enable: Optional callback to enable the trigger for the
+	 * given offload instance.
+	 */
+	int (*trigger_enable)(struct spi_offload *offload);
+	/**
+	 * @trigger_disable: Optional callback to disable the trigger for the
+	 * given offload instance.
+	 */
+	void (*trigger_disable)(struct spi_offload *offload);
+	/**
+	 * @tx_stream_request_dma_chan: Optional callback for controllers that
+	 * have an offload where the TX data stream is connected directly to a
+	 * DMA channel.
+	 */
+	struct dma_chan *(*tx_stream_request_dma_chan)(struct spi_offload *offload);
+	/**
+	 * @rx_stream_request_dma_chan: Optional callback for controllers that
+	 * have an offload where the RX data stream is connected directly to a
+	 * DMA channel.
+	 */
+	struct dma_chan *(*rx_stream_request_dma_chan)(struct spi_offload *offload);
+};
+
+#endif /* __LINUX_SPI_OFFLOAD_TYPES_H */

include/linux/spi/spi.h

···
 struct spi_controller_mem_ops;
 struct spi_controller_mem_caps;
 struct spi_message;
+struct spi_offload;
+struct spi_offload_config;
 
 /*
  * INTERFACES between SPI master-side drivers and SPI slave protocol handlers,
···
  * @mem_ops: optimized/dedicated operations for interactions with SPI memory.
  *	     This field is optional and should only be implemented if the
  *	     controller has native support for memory like operations.
+ * @get_offload: callback for controllers with offload support to get matching
+ *	offload instance. Implementations should return -ENODEV if no match is
+ *	found.
+ * @put_offload: release the offload instance acquired by @get_offload.
  * @mem_caps: controller capabilities for the handling of memory operations.
  * @unprepare_message: undo any work done by prepare_message().
  * @target_abort: abort the ongoing transfer request on an SPI target controller
···
 	/* Optimized handlers for SPI memory-like operations. */
 	const struct spi_controller_mem_ops *mem_ops;
 	const struct spi_controller_mem_caps *mem_caps;
+
+	struct spi_offload *(*get_offload)(struct spi_device *spi,
+					   const struct spi_offload_config *config);
+	void (*put_offload)(struct spi_offload *offload);
 
 	/* GPIO chip select */
 	struct gpio_desc	**cs_gpiods;
···
 
 	u32		effective_speed_hz;
 
+	/* Use %SPI_OFFLOAD_XFER_* from spi-offload.h */
+	unsigned int	offload_flags;
+
 	unsigned int	ptp_sts_word_pre;
 	unsigned int	ptp_sts_word_post;
 
···
  * @state: for use by whichever driver currently owns the message
  * @opt_state: for use by whichever driver currently owns the message
  * @resources: for resource management when the SPI message is processed
+ * @offload: (optional) offload instance used by this message
  *
  * A @spi_message is used to execute an atomic sequence of data transfers,
  * each represented by a struct spi_transfer.  The sequence is "atomic"
···
 	 * __spi_optimize_message() and __spi_unoptimize_message().
 	 */
 	void			*opt_state;
+
+	/*
+	 * Optional offload instance used by this message. This must be set
+	 * by the peripheral driver before calling spi_optimize_message().
+	 */
+	struct spi_offload	*offload;
 
 	/* List of spi_res resources when the SPI message is processed */
 	struct list_head        resources;