[PATCH v4 1/7] spi: Extend the core to ease integration of SPI memory controllers
Boris Brezillon
boris.brezillon at bootlin.com
Thu Apr 26 09:18:14 PDT 2018
Some controllers are exposing high-level interfaces to access various
kind of SPI memories. Unfortunately they do not fit in the current
spi_controller model and usually have drivers placed in
drivers/mtd/spi-nor which are only supporting SPI NORs and not SPI
memories in general.
This is an attempt at defining a SPI memory interface which works for
all kinds of SPI memories (NORs, NANDs, SRAMs).
Signed-off-by: Boris Brezillon <boris.brezillon at bootlin.com>
---
Changes in v4:
- none
Changes in v3:
- Fix check in spi_mem_supports_op()
- Include internals.h
Changes in v2:
- Move all changes not directly related to spi_mem out of this commit
- Do not abuse ternary operation
- Reword a few comments and fix typos
- Do not make the default buswidth check in spi_mem_support_ops() if
the controller implements this hook
- Make the addr value an u64 instead of an array of byte
- Move all spi-mem code/defs to separate header/source files and add a
new Kconfig option to enable this interface
---
drivers/spi/Kconfig | 7 +
drivers/spi/Makefile | 1 +
drivers/spi/spi-mem.c | 410 ++++++++++++++++++++++++++++++++++++++++++++
include/linux/spi/spi-mem.h | 249 +++++++++++++++++++++++++++
include/linux/spi/spi.h | 7 +
5 files changed, 674 insertions(+)
create mode 100644 drivers/spi/spi-mem.c
create mode 100644 include/linux/spi/spi-mem.h
diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index 2d4146ce2f1b..59936ab80a0d 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -47,6 +47,13 @@ config SPI_MASTER
if SPI_MASTER
+config SPI_MEM
+ bool "SPI memory extension"
+ help
+ Enable this option if you want to enable the SPI memory extension.
+ This extension is meant to simplify interaction with SPI memories
+ by providing an high-level interface to send memory-like commands.
+
comment "SPI Master Controller Drivers"
config SPI_ALTERA
diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
index b935f10eb961..79d6f1c7b05b 100644
--- a/drivers/spi/Makefile
+++ b/drivers/spi/Makefile
@@ -8,6 +8,7 @@ ccflags-$(CONFIG_SPI_DEBUG) := -DDEBUG
# small core, mostly translating board-specific
# config declarations into driver model code
obj-$(CONFIG_SPI_MASTER) += spi.o
+obj-$(CONFIG_SPI_MEM) += spi-mem.o
obj-$(CONFIG_SPI_SPIDEV) += spidev.o
obj-$(CONFIG_SPI_LOOPBACK_TEST) += spi-loopback-test.o
diff --git a/drivers/spi/spi-mem.c b/drivers/spi/spi-mem.c
new file mode 100644
index 000000000000..990770dfa5cf
--- /dev/null
+++ b/drivers/spi/spi-mem.c
@@ -0,0 +1,410 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2018 Exceet Electronics GmbH
+ * Copyright (C) 2018 Bootlin
+ *
+ * Author: Boris Brezillon <boris.brezillon at bootlin.com>
+ */
+#include <linux/dmaengine.h>
+#include <linux/pm_runtime.h>
+#include <linux/spi/spi.h>
+#include <linux/spi/spi-mem.h>
+
+#include "internals.h"
+
+/**
+ * spi_controller_dma_map_mem_op_data() - DMA-map the buffer attached to a
+ * memory operation
+ * @ctlr: the SPI controller requesting this dma_map()
+ * @op: the memory operation containing the buffer to map
+ * @sgt: a pointer to a non-initialized sg_table that will be filled by this
+ * function
+ *
+ * Some controllers might want to do DMA on the data buffer embedded in @op.
+ * This helper prepares everything for you and provides a ready-to-use
+ * sg_table. This function is not intended to be called from spi drivers.
+ * Only SPI controller drivers should use it.
+ * Note that the caller must ensure the memory region pointed by
+ * op->data.buf.{in,out} is DMA-able before calling this function.
+ *
+ * Return: 0 in case of success, a negative error code otherwise.
+ */
+int spi_controller_dma_map_mem_op_data(struct spi_controller *ctlr,
+ const struct spi_mem_op *op,
+ struct sg_table *sgt)
+{
+ struct device *dmadev;
+
+ if (!op->data.nbytes)
+ return -EINVAL;
+
+ if (op->data.dir == SPI_MEM_DATA_OUT && ctlr->dma_tx)
+ dmadev = ctlr->dma_tx->device->dev;
+ else if (op->data.dir == SPI_MEM_DATA_IN && ctlr->dma_rx)
+ dmadev = ctlr->dma_rx->device->dev;
+ else
+ dmadev = ctlr->dev.parent;
+
+ if (!dmadev)
+ return -EINVAL;
+
+ return spi_map_buf(ctlr, dmadev, sgt, op->data.buf.in, op->data.nbytes,
+ op->data.dir == SPI_MEM_DATA_IN ?
+ DMA_FROM_DEVICE : DMA_TO_DEVICE);
+}
+EXPORT_SYMBOL_GPL(spi_controller_dma_map_mem_op_data);
+
+/**
+ * spi_controller_dma_unmap_mem_op_data() - DMA-unmap the buffer attached to a
+ * memory operation
+ * @ctlr: the SPI controller requesting this dma_unmap()
+ * @op: the memory operation containing the buffer to unmap
+ * @sgt: a pointer to an sg_table previously initialized by
+ * spi_controller_dma_map_mem_op_data()
+ *
+ * Some controllers might want to do DMA on the data buffer embedded in @op.
+ * This helper prepares things so that the CPU can access the
+ * op->data.buf.{in,out} buffer again.
+ *
+ * This function is not intended to be called from SPI drivers. Only SPI
+ * controller drivers should use it.
+ *
+ * This function should be called after the DMA operation has finished and is
+ * only valid if the previous spi_controller_dma_map_mem_op_data() call
+ * returned 0.
+ *
+ * Return: 0 in case of success, a negative error code otherwise.
+ */
+void spi_controller_dma_unmap_mem_op_data(struct spi_controller *ctlr,
+ const struct spi_mem_op *op,
+ struct sg_table *sgt)
+{
+ struct device *dmadev;
+
+ if (!op->data.nbytes)
+ return;
+
+ if (op->data.dir == SPI_MEM_DATA_OUT && ctlr->dma_tx)
+ dmadev = ctlr->dma_tx->device->dev;
+ else if (op->data.dir == SPI_MEM_DATA_IN && ctlr->dma_rx)
+ dmadev = ctlr->dma_rx->device->dev;
+ else
+ dmadev = ctlr->dev.parent;
+
+ spi_unmap_buf(ctlr, dmadev, sgt,
+ op->data.dir == SPI_MEM_DATA_IN ?
+ DMA_FROM_DEVICE : DMA_TO_DEVICE);
+}
+EXPORT_SYMBOL_GPL(spi_controller_dma_unmap_mem_op_data);
+
+static int spi_check_buswidth_req(struct spi_mem *mem, u8 buswidth, bool tx)
+{
+ u32 mode = mem->spi->mode;
+
+ switch (buswidth) {
+ case 1:
+ return 0;
+
+ case 2:
+ if ((tx && (mode & (SPI_TX_DUAL | SPI_TX_QUAD))) ||
+ (!tx && (mode & (SPI_RX_DUAL | SPI_RX_QUAD))))
+ return 0;
+
+ break;
+
+ case 4:
+ if ((tx && (mode & SPI_TX_QUAD)) ||
+ (!tx && (mode & SPI_RX_QUAD)))
+ return 0;
+
+ break;
+
+ default:
+ break;
+ }
+
+ return -ENOTSUPP;
+}
+
+static bool spi_mem_default_supports_op(struct spi_mem *mem,
+ const struct spi_mem_op *op)
+{
+ if (spi_check_buswidth_req(mem, op->cmd.buswidth, true))
+ return false;
+
+ if (op->addr.nbytes &&
+ spi_check_buswidth_req(mem, op->addr.buswidth, true))
+ return false;
+
+ if (op->dummy.nbytes &&
+ spi_check_buswidth_req(mem, op->dummy.buswidth, true))
+ return false;
+
+ if (op->data.nbytes &&
+ spi_check_buswidth_req(mem, op->data.buswidth,
+ op->data.dir == SPI_MEM_DATA_OUT))
+ return false;
+
+ return true;
+}
+EXPORT_SYMBOL_GPL(spi_mem_default_supports_op);
+
+/**
+ * spi_mem_supports_op() - Check if a memory device and the controller it is
+ * connected to support a specific memory operation
+ * @mem: the SPI memory
+ * @op: the memory operation to check
+ *
+ * Some controllers are only supporting Single or Dual IOs, others might only
+ * support specific opcodes, or it can even be that the controller and device
+ * both support Quad IOs but the hardware prevents you from using it because
+ * only 2 IO lines are connected.
+ *
+ * This function checks whether a specific operation is supported.
+ *
+ * Return: true if @op is supported, false otherwise.
+ */
+bool spi_mem_supports_op(struct spi_mem *mem, const struct spi_mem_op *op)
+{
+ struct spi_controller *ctlr = mem->spi->controller;
+
+ if (ctlr->mem_ops && ctlr->mem_ops->supports_op)
+ return ctlr->mem_ops->supports_op(mem, op);
+
+ return spi_mem_default_supports_op(mem, op);
+}
+EXPORT_SYMBOL_GPL(spi_mem_supports_op);
+
+/**
+ * spi_mem_exec_op() - Execute a memory operation
+ * @mem: the SPI memory
+ * @op: the memory operation to execute
+ *
+ * Executes a memory operation.
+ *
+ * This function first checks that @op is supported and then tries to execute
+ * it.
+ *
+ * Return: 0 in case of success, a negative error code otherwise.
+ */
+int spi_mem_exec_op(struct spi_mem *mem, const struct spi_mem_op *op)
+{
+ unsigned int tmpbufsize, xferpos = 0, totalxferlen = 0;
+ struct spi_controller *ctlr = mem->spi->controller;
+ struct spi_transfer xfers[4] = { };
+ struct spi_message msg;
+ u8 *tmpbuf;
+ int ret;
+
+ if (!spi_mem_supports_op(mem, op))
+ return -ENOTSUPP;
+
+ if (ctlr->mem_ops) {
+ /*
+ * Flush the message queue before executing our SPI memory
+ * operation to prevent preemption of regular SPI transfers.
+ */
+ spi_flush_queue(ctlr);
+
+ if (ctlr->auto_runtime_pm) {
+ ret = pm_runtime_get_sync(ctlr->dev.parent);
+ if (ret < 0) {
+ dev_err(&ctlr->dev,
+ "Failed to power device: %d\n",
+ ret);
+ return ret;
+ }
+ }
+
+ mutex_lock(&ctlr->bus_lock_mutex);
+ mutex_lock(&ctlr->io_mutex);
+ ret = ctlr->mem_ops->exec_op(mem, op);
+ mutex_unlock(&ctlr->io_mutex);
+ mutex_unlock(&ctlr->bus_lock_mutex);
+
+ if (ctlr->auto_runtime_pm)
+ pm_runtime_put(ctlr->dev.parent);
+
+ /*
+ * Some controllers only optimize specific paths (typically the
+ * read path) and expect the core to use the regular SPI
+ * interface in other cases.
+ */
+ if (!ret || ret != -ENOTSUPP)
+ return ret;
+ }
+
+ tmpbufsize = sizeof(op->cmd.opcode) + op->addr.nbytes +
+ op->dummy.nbytes;
+
+ /*
+ * Allocate a buffer to transmit the CMD, ADDR cycles with kmalloc() so
+ * we're guaranteed that this buffer is DMA-able, as required by the
+ * SPI layer.
+ */
+ tmpbuf = kzalloc(tmpbufsize, GFP_KERNEL | GFP_DMA);
+ if (!tmpbuf)
+ return -ENOMEM;
+
+ spi_message_init(&msg);
+
+ tmpbuf[0] = op->cmd.opcode;
+ xfers[xferpos].tx_buf = tmpbuf;
+ xfers[xferpos].len = sizeof(op->cmd.opcode);
+ xfers[xferpos].tx_nbits = op->cmd.buswidth;
+ spi_message_add_tail(&xfers[xferpos], &msg);
+ xferpos++;
+ totalxferlen++;
+
+ if (op->addr.nbytes) {
+ int i;
+
+ for (i = 0; i < op->addr.nbytes; i++)
+ tmpbuf[i + 1] = op->addr.val >>
+ (8 * (op->addr.nbytes - i - 1));
+
+ xfers[xferpos].tx_buf = tmpbuf + 1;
+ xfers[xferpos].len = op->addr.nbytes;
+ xfers[xferpos].tx_nbits = op->addr.buswidth;
+ spi_message_add_tail(&xfers[xferpos], &msg);
+ xferpos++;
+ totalxferlen += op->addr.nbytes;
+ }
+
+ if (op->dummy.nbytes) {
+ memset(tmpbuf + op->addr.nbytes + 1, 0xff, op->dummy.nbytes);
+ xfers[xferpos].tx_buf = tmpbuf + op->addr.nbytes + 1;
+ xfers[xferpos].len = op->dummy.nbytes;
+ xfers[xferpos].tx_nbits = op->dummy.buswidth;
+ spi_message_add_tail(&xfers[xferpos], &msg);
+ xferpos++;
+ totalxferlen += op->dummy.nbytes;
+ }
+
+ if (op->data.nbytes) {
+ if (op->data.dir == SPI_MEM_DATA_IN) {
+ xfers[xferpos].rx_buf = op->data.buf.in;
+ xfers[xferpos].rx_nbits = op->data.buswidth;
+ } else {
+ xfers[xferpos].tx_buf = op->data.buf.out;
+ xfers[xferpos].tx_nbits = op->data.buswidth;
+ }
+
+ xfers[xferpos].len = op->data.nbytes;
+ spi_message_add_tail(&xfers[xferpos], &msg);
+ xferpos++;
+ totalxferlen += op->data.nbytes;
+ }
+
+ ret = spi_sync(mem->spi, &msg);
+
+ kfree(tmpbuf);
+
+ if (ret)
+ return ret;
+
+ if (msg.actual_length != totalxferlen)
+ return -EIO;
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(spi_mem_exec_op);
+
+/**
+ * spi_mem_adjust_op_size() - Adjust the data size of a SPI mem operation to
+ * match controller limitations
+ * @mem: the SPI memory
+ * @op: the operation to adjust
+ *
+ * Some controllers have FIFO limitations and must split a data transfer
+ * operation into multiple ones, others require a specific alignment for
+ * optimized accesses. This function allows SPI mem drivers to split a single
+ * operation into multiple sub-operations when required.
+ *
+ * Return: a negative error code if the controller can't properly adjust @op,
+ * 0 otherwise. Note that @op->data.nbytes will be updated if @op
+ * can't be handled in a single step.
+ */
+int spi_mem_adjust_op_size(struct spi_mem *mem, struct spi_mem_op *op)
+{
+ struct spi_controller *ctlr = mem->spi->controller;
+
+ if (ctlr->mem_ops && ctlr->mem_ops->adjust_op_size)
+ return ctlr->mem_ops->adjust_op_size(mem, op);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(spi_mem_adjust_op_size);
+
+static inline struct spi_mem_driver *to_spi_mem_drv(struct device_driver *drv)
+{
+ return container_of(drv, struct spi_mem_driver, spidrv.driver);
+}
+
+static int spi_mem_probe(struct spi_device *spi)
+{
+ struct spi_mem_driver *memdrv = to_spi_mem_drv(spi->dev.driver);
+ struct spi_mem *mem;
+
+ mem = devm_kzalloc(&spi->dev, sizeof(*mem), GFP_KERNEL);
+ if (!mem)
+ return -ENOMEM;
+
+ mem->spi = spi;
+ spi_set_drvdata(spi, mem);
+
+ return memdrv->probe(mem);
+}
+
+static int spi_mem_remove(struct spi_device *spi)
+{
+ struct spi_mem_driver *memdrv = to_spi_mem_drv(spi->dev.driver);
+ struct spi_mem *mem = spi_get_drvdata(spi);
+
+ if (memdrv->remove)
+ return memdrv->remove(mem);
+
+ return 0;
+}
+
+static void spi_mem_shutdown(struct spi_device *spi)
+{
+ struct spi_mem_driver *memdrv = to_spi_mem_drv(spi->dev.driver);
+ struct spi_mem *mem = spi_get_drvdata(spi);
+
+ if (memdrv->shutdown)
+ memdrv->shutdown(mem);
+}
+
+/**
+ * spi_mem_driver_register_with_owner() - Register a SPI memory driver
+ * @memdrv: the SPI memory driver to register
+ * @owner: the owner of this driver
+ *
+ * Registers a SPI memory driver.
+ *
+ * Return: 0 in case of success, a negative error core otherwise.
+ */
+
+int spi_mem_driver_register_with_owner(struct spi_mem_driver *memdrv,
+ struct module *owner)
+{
+ memdrv->spidrv.probe = spi_mem_probe;
+ memdrv->spidrv.remove = spi_mem_remove;
+ memdrv->spidrv.shutdown = spi_mem_shutdown;
+
+ return __spi_register_driver(owner, &memdrv->spidrv);
+}
+EXPORT_SYMBOL_GPL(spi_mem_driver_register_with_owner);
+
+/**
+ * spi_mem_driver_unregister_with_owner() - Unregister a SPI memory driver
+ * @memdrv: the SPI memory driver to unregister
+ *
+ * Unregisters a SPI memory driver.
+ */
+void spi_mem_driver_unregister(struct spi_mem_driver *memdrv)
+{
+ spi_unregister_driver(&memdrv->spidrv);
+}
+EXPORT_SYMBOL_GPL(spi_mem_driver_unregister);
diff --git a/include/linux/spi/spi-mem.h b/include/linux/spi/spi-mem.h
new file mode 100644
index 000000000000..bb4bd15ae1f6
--- /dev/null
+++ b/include/linux/spi/spi-mem.h
@@ -0,0 +1,249 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Copyright (C) 2018 Exceet Electronics GmbH
+ * Copyright (C) 2018 Bootlin
+ *
+ * Author: Boris Brezillon <boris.brezillon at bootlin.com>
+ */
+
+#ifndef __LINUX_SPI_MEM_H
+#define __LINUX_SPI_MEM_H
+
+#include <linux/spi/spi.h>
+
+#define SPI_MEM_OP_CMD(__opcode, __buswidth) \
+ { \
+ .buswidth = __buswidth, \
+ .opcode = __opcode, \
+ }
+
+#define SPI_MEM_OP_ADDR(__nbytes, __val, __buswidth) \
+ { \
+ .nbytes = __nbytes, \
+ .val = __val, \
+ .buswidth = __buswidth, \
+ }
+
+#define SPI_MEM_OP_NO_ADDR { }
+
+#define SPI_MEM_OP_DUMMY(__nbytes, __buswidth) \
+ { \
+ .nbytes = __nbytes, \
+ .buswidth = __buswidth, \
+ }
+
+#define SPI_MEM_OP_NO_DUMMY { }
+
+#define SPI_MEM_OP_DATA_IN(__nbytes, __buf, __buswidth) \
+ { \
+ .dir = SPI_MEM_DATA_IN, \
+ .nbytes = __nbytes, \
+ .buf.in = __buf, \
+ .buswidth = __buswidth, \
+ }
+
+#define SPI_MEM_OP_DATA_OUT(__nbytes, __buf, __buswidth) \
+ { \
+ .dir = SPI_MEM_DATA_OUT, \
+ .nbytes = __nbytes, \
+ .buf.out = __buf, \
+ .buswidth = __buswidth, \
+ }
+
+#define SPI_MEM_OP_NO_DATA { }
+
+/**
+ * enum spi_mem_data_dir - describes the direction of a SPI memory data
+ * transfer from the controller perspective
+ * @SPI_MEM_DATA_IN: data coming from the SPI memory
+ * @SPI_MEM_DATA_OUT: data sent the SPI memory
+ */
+enum spi_mem_data_dir {
+ SPI_MEM_DATA_IN,
+ SPI_MEM_DATA_OUT,
+};
+
+/**
+ * struct spi_mem_op - describes a SPI memory operation
+ * @cmd.buswidth: number of IO lines used to transmit the command
+ * @cmd.opcode: operation opcode
+ * @addr.nbytes: number of address bytes to send. Can be zero if the operation
+ * does not need to send an address
+ * @addr.buswidth: number of IO lines used to transmit the address cycles
+ * @addr.val: address value. This value is always sent MSB first on the bus.
+ * Note that only @addr.nbytes are taken into account in this
+ * address value, so users should make sure the value fits in the
+ * assigned number of bytes.
+ * @dummy.nbytes: number of dummy bytes to send after an opcode or address. Can
+ * be zero if the operation does not require dummy bytes
+ * @dummy.buswidth: number of IO lanes used to transmit the dummy bytes
+ * @data.buswidth: number of IO lanes used to send/receive the data
+ * @data.dir: direction of the transfer
+ * @data.buf.in: input buffer
+ * @data.buf.out: output buffer
+ */
+struct spi_mem_op {
+ struct {
+ u8 buswidth;
+ u8 opcode;
+ } cmd;
+
+ struct {
+ u8 nbytes;
+ u8 buswidth;
+ u64 val;
+ } addr;
+
+ struct {
+ u8 nbytes;
+ u8 buswidth;
+ } dummy;
+
+ struct {
+ u8 buswidth;
+ enum spi_mem_data_dir dir;
+ unsigned int nbytes;
+ /* buf.{in,out} must be DMA-able. */
+ union {
+ void *in;
+ const void *out;
+ } buf;
+ } data;
+};
+
+#define SPI_MEM_OP(__cmd, __addr, __dummy, __data) \
+ { \
+ .cmd = __cmd, \
+ .addr = __addr, \
+ .dummy = __dummy, \
+ .data = __data, \
+ }
+
+/**
+ * struct spi_mem - describes a SPI memory device
+ * @spi: the underlying SPI device
+ * @drvpriv: spi_mem_drviver private data
+ *
+ * Extra information that describe the SPI memory device and may be needed by
+ * the controller to properly handle this device should be placed here.
+ *
+ * One example would be the device size since some controller expose their SPI
+ * mem devices through a io-mapped region.
+ */
+struct spi_mem {
+ struct spi_device *spi;
+ void *drvpriv;
+};
+
+/**
+ * struct spi_mem_set_drvdata() - attach driver private data to a SPI mem
+ * device
+ * @mem: memory device
+ * @data: data to attach to the memory device
+ */
+static inline void spi_mem_set_drvdata(struct spi_mem *mem, void *data)
+{
+ mem->drvpriv = data;
+}
+
+/**
+ * struct spi_mem_get_drvdata() - get driver private data attached to a SPI mem
+ * device
+ * @mem: memory device
+ *
+ * Return: the data attached to the mem device.
+ */
+static inline void *spi_mem_get_drvdata(struct spi_mem *mem)
+{
+ return mem->drvpriv;
+}
+
+/**
+ * struct spi_controller_mem_ops - SPI memory operations
+ * @adjust_op_size: shrink the data xfer of an operation to match controller's
+ * limitations (can be alignment of max RX/TX size
+ * limitations)
+ * @supports_op: check if an operation is supported by the controller
+ * @exec_op: execute a SPI memory operation
+ *
+ * This interface should be implemented by SPI controllers providing an
+ * high-level interface to execute SPI memory operation, which is usually the
+ * case for QSPI controllers.
+ */
+struct spi_controller_mem_ops {
+ int (*adjust_op_size)(struct spi_mem *mem, struct spi_mem_op *op);
+ bool (*supports_op)(struct spi_mem *mem,
+ const struct spi_mem_op *op);
+ int (*exec_op)(struct spi_mem *mem,
+ const struct spi_mem_op *op);
+};
+
+/**
+ * struct spi_mem_driver - SPI memory driver
+ * @spidrv: inherit from a SPI driver
+ * @probe: probe a SPI memory. Usually where detection/initialization takes
+ * place
+ * @remove: remove a SPI memory
+ * @shutdown: take appropriate action when the system is shutdown
+ *
+ * This is just a thin wrapper around a spi_driver. The core takes care of
+ * allocating the spi_mem object and forwarding the probe/remove/shutdown
+ * request to the spi_mem_driver. The reason we use this wrapper is because
+ * we might have to stuff more information into the spi_mem struct to let
+ * SPI controllers know more about the SPI memory they interact with, and
+ * having this intermediate layer allows us to do that without adding more
+ * useless fields to the spi_device object.
+ */
+struct spi_mem_driver {
+ struct spi_driver spidrv;
+ int (*probe)(struct spi_mem *mem);
+ int (*remove)(struct spi_mem *mem);
+ void (*shutdown)(struct spi_mem *mem);
+};
+
+#if IS_ENABLED(CONFIG_SPI_MEM)
+int spi_controller_dma_map_mem_op_data(struct spi_controller *ctlr,
+ const struct spi_mem_op *op,
+ struct sg_table *sg);
+
+void spi_controller_dma_unmap_mem_op_data(struct spi_controller *ctlr,
+ const struct spi_mem_op *op,
+ struct sg_table *sg);
+#else
+static inline int
+spi_controller_dma_map_mem_op_data(struct spi_controller *ctlr,
+ const struct spi_mem_op *op,
+ struct sg_table *sg)
+{
+ return -ENOTSUPP;
+}
+
+static inline void
+spi_controller_dma_unmap_mem_op_data(struct spi_controller *ctlr,
+ const struct spi_mem_op *op,
+ struct sg_table *sg)
+{
+}
+#endif /* CONFIG_SPI_MEM */
+
+int spi_mem_adjust_op_size(struct spi_mem *mem, struct spi_mem_op *op);
+
+bool spi_mem_supports_op(struct spi_mem *mem,
+ const struct spi_mem_op *op);
+
+int spi_mem_exec_op(struct spi_mem *mem,
+ const struct spi_mem_op *op);
+
+int spi_mem_driver_register_with_owner(struct spi_mem_driver *drv,
+ struct module *owner);
+
+void spi_mem_driver_unregister(struct spi_mem_driver *drv);
+
+#define spi_mem_driver_register(__drv) \
+ spi_mem_driver_register_with_owner(__drv, THIS_MODULE)
+
+#define module_spi_mem_driver(__drv) \
+ module_driver(__drv, spi_mem_driver_register, \
+ spi_mem_driver_unregister)
+
+#endif /* __LINUX_SPI_MEM_H */
diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
index bc6bb325d1bf..a7e0bbed738c 100644
--- a/include/linux/spi/spi.h
+++ b/include/linux/spi/spi.h
@@ -27,6 +27,7 @@ struct property_entry;
struct spi_controller;
struct spi_transfer;
struct spi_flash_read_message;
+struct spi_controller_mem_ops;
/*
* INTERFACES between SPI master-side drivers and SPI slave protocol handlers,
@@ -376,6 +377,9 @@ static inline void spi_unregister_driver(struct spi_driver *sdrv)
* transfer_one callback.
* @handle_err: the subsystem calls the driver to handle an error that occurs
* in the generic implementation of transfer_one_message().
+ * @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.
* @unprepare_message: undo any work done by prepare_message().
* @slave_abort: abort the ongoing transfer request on an SPI slave controller
* @spi_flash_read: to support spi-controller hardwares that provide
@@ -564,6 +568,9 @@ struct spi_controller {
void (*handle_err)(struct spi_controller *ctlr,
struct spi_message *message);
+ /* Optimized handlers for SPI memory-like operations. */
+ const struct spi_controller_mem_ops *mem_ops;
+
/* gpio chip select */
int *cs_gpios;
--
2.14.1
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