[RFC PATCH 1/6] spi: Extend the core to ease integration of SPI memory controllers
Cyrille Pitchen
cyrille.pitchen at wedev4u.fr
Sun Mar 4 13:15:20 PST 2018
Hi Boris,
Le 06/02/2018 à 00:21, Boris Brezillon a écrit :
> From: Boris Brezillon <boris.brezillon at free-electrons.com>
>
> 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 free-electrons.com>
> ---
> drivers/spi/spi.c | 423 +++++++++++++++++++++++++++++++++++++++++++++++-
> include/linux/spi/spi.h | 226 ++++++++++++++++++++++++++
> 2 files changed, 646 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
> index b33a727a0158..57bc540a0521 100644
> --- a/drivers/spi/spi.c
> +++ b/drivers/spi/spi.c
> @@ -2057,6 +2057,24 @@ static int of_spi_register_master(struct spi_controller *ctlr)
> }
> #endif
>
> +static int spi_controller_check_ops(struct spi_controller *ctlr)
> +{
> + /*
> + * The controller can implement only the high-level SPI-memory like
> + * operations if it does not support regular SPI transfers.
> + */
> + if (ctlr->mem_ops) {
> + if (!ctlr->mem_ops->supports_op ||
> + !ctlr->mem_ops->exec_op)
> + return -EINVAL;
> + } else if (!ctlr->transfer && !ctlr->transfer_one &&
> + !ctlr->transfer_one_message) {
> + return -EINVAL;
> + }
> +
> + return 0;
> +}
> +
> /**
> * spi_register_controller - register SPI master or slave controller
> * @ctlr: initialized master, originally from spi_alloc_master() or
> @@ -2090,6 +2108,14 @@ int spi_register_controller(struct spi_controller *ctlr)
> if (!dev)
> return -ENODEV;
>
> + /*
> + * Make sure all necessary hooks are implemented before registering
> + * the SPI controller.
> + */
> + status = spi_controller_check_ops(ctlr);
> + if (status)
> + return status;
> +
> if (!spi_controller_is_slave(ctlr)) {
> status = of_spi_register_master(ctlr);
> if (status)
> @@ -2155,10 +2181,14 @@ int spi_register_controller(struct spi_controller *ctlr)
> spi_controller_is_slave(ctlr) ? "slave" : "master",
> dev_name(&ctlr->dev));
>
> - /* If we're using a queued driver, start the queue */
> - if (ctlr->transfer)
> + /*
> + * If we're using a queued driver, start the queue. Note that we don't
> + * need the queueing logic if the driver is only supporting high-level
> + * memory operations.
> + */
> + if (ctlr->transfer) {
> dev_info(dev, "controller is unqueued, this is deprecated\n");
> - else {
> + } else if (ctlr->transfer_one || ctlr->transfer_one_message) {
> status = spi_controller_initialize_queue(ctlr);
> if (status) {
> device_del(&ctlr->dev);
> @@ -2893,6 +2923,13 @@ static int __spi_async(struct spi_device *spi, struct spi_message *message)
> {
> struct spi_controller *ctlr = spi->controller;
>
> + /*
> + * Some controllers do not support doing regular SPI transfers. Return
> + * ENOTSUPP when this is the case.
> + */
> + if (!ctlr->transfer)
> + return -ENOTSUPP;
> +
> message->spi = spi;
>
> SPI_STATISTICS_INCREMENT_FIELD(&ctlr->statistics, spi_async);
> @@ -3321,6 +3358,386 @@ int spi_write_then_read(struct spi_device *spi,
> }
> EXPORT_SYMBOL_GPL(spi_write_then_read);
>
> +/**
> + * 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)
> + dmadev = ctlr->dma_tx ?
> + ctlr->dma_tx->device->dev : ctlr->dev.parent;
> + else
> + dmadev = ctlr->dma_rx ?
> + ctlr->dma_rx->device->dev : 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 an is
> + * only valid if the previous spi_controller_dma_map_mem_op_data() has 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)
> + dmadev = ctlr->dma_tx ?
> + ctlr->dma_tx->device->dev : ctlr->dev.parent;
> + else
> + dmadev = ctlr->dma_rx ?
> + ctlr->dma_rx->device->dev : 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))))
Some SPI (flash) controller may support Quad protocols but no Duals
protocols at all. Hence you should only test SPI_{R,T]X_DUAL.
Anyway, I think the function should completely be removed because
SPI_{R,T}X_{DUAL,QUAD} flags should be deprecated.
They were fine when introduced long time ago when Quad SPI flashes only
supported Fast Read 1-1-4 and maybe few of them Page Program 1-1-4.
However for many years now, Quad SPI flashes support far much SPI protocols
and commands. For instance:
Fast Read 1-1-4
Fast Read 1-4-4
(Fast Read 4-4-4)
Page Program 1-1-4
Page Program 1-4-4
Page Program 4-4-4
Fast Read x-y-z means that:
- the op code is transfered (tx) on x I/O line(s)
- the address, mode and dummies are transfered (tx) on y I/O line(s)
- the data are received (rx) on z I/O line(s)
Page Program x-y-z stands for:
- the op code being transfered (tx) on x I/O line(s)
- the address is transfered (tx) on y I/O line(s)
the data are transfered (tx) on z I/O line(s)
Then some SPI flash controllers and/or memories may support Fast Read 1-4-4
but not Page Program 1-1-4 whereas others may support Page Program 1-1-4
but not Fast Read 1-4-4.
So using only SPI_{R,T}X_{DUAL,QUAD} flags, how do we make the difference
between support of Fast Read 1-4-4 and Page Program 1-1-4 or between
Fast Read 1-1-4 and Fast Read 1-4-4 ?
Indeed some latest (Cypress) memories only support Fast Read 1-4-4 but no
longer Fast Read 1-1-4.
I guess we'd rather use something close to the SNOR_HWCAPS_* macros as
defined in include/linux/mtd/spi-nor.h
SPI_{R,T}X_{DUAL,QUAD} flags are no longer suited to SPI flash memories for
a long time now.
> + return 0;
> +
> + break;
> +
> + case 4:
> + if ((tx && (mode & SPI_TX_QUAD)) ||
> + (!tx && (mode & SPI_RX_QUAD)))
> + return 0;
> +
> + break;
> +
> + default:
> + break;
> + }
> +
> + return -ENOTSUPP;
> +}
> +
> +/**
> + * 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 (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_IN ?
> + false : true))
> + return false;
You should remove the 4 tests and calls of spi_check_buswidth_req() above.
Based on spi_controller_check_ops(), when ctrl->mem_ops is not NULL,
mem_ops->supports_op() must be provided, this hook is mandatory.
So call this latest hook only, has done just below. You may want to keep the 4
tests above and spi_check_buswidth_req() but then move them in a
stand-alone function that could be used as a default implementation of
mem_ops->supports_op() if you want to allow some SPI controller drivers not
to implement ->supports_op() by their own.
However it should be considered a transitionnal and at some point I think
SPI_{R,T}X_{DUAL,QUAD} flags should just be removed because many
developers submitting patches to spi-nor have often been confused by how
properly use those flags in their drivers.
Till then, if you removed the 4 tests above, at least new SPI flash
controller drivers won't have to set some odd combination of flags in
spi->mode to make their support of SPI flash memories work as they want.
> +
> + if (ctlr->mem_ops)
> + return ctlr->mem_ops->supports_op(mem, op);
> +
> + return true;
> +}
> +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) {
> + 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 these 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) {
> + memcpy(tmpbuf + 1, op->addr.buf, op->addr.nbytes);
> + 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);
> +
> /*-------------------------------------------------------------------------*/
>
> #if IS_ENABLED(CONFIG_OF_DYNAMIC)
> diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
> index 7b2170bfd6e7..af3c4ac62b55 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;
>
> @@ -1227,6 +1234,225 @@ int spi_flash_read(struct spi_device *spi,
>
> /*---------------------------------------------------------------------------*/
>
> +/* SPI memory related definitions. */
> +
> +#define SPI_MEM_OP_CMD(__opcode, __buswidth) \
> + { \
> + .buswidth = __buswidth, \
> + .opcode = __opcode, \
> + }
> +
> +#define SPI_MEM_OP_ADDRS(__nbytes, __buf, __buswidth) \
> + { \
> + .nbytes = __nbytes, \
> + .buf = __buf, \
> + .buswidth = __buswidth, \
> + }
> +
> +#define SPI_MEM_OP_NO_ADDRS { }
> +
> +#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.buf: buffer storing the address 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;
> + const u8 *buf;
For the address value, I would rather use some loff_t type, instead of
const u8 *.
Actually, most (if not all) SPI flash controllers have some hardware
register to set the address value of the SPI flash command to be
sent. Hence having this value directly in the right format would avoid to
convert. AFAIK, only m25p80 needs to convert from loff_t to u8 * and only
when using the regular SPI API, ie spi_sync(), as the 'struct
spi_flash_read_messag' already uses some integral type too.
> + } 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;
Also, you should add another member in this structure to set the 'type' of
operation for the SPI flash command:
- register read
- register write
- memory read
- memory write
- memory erase
[- SFDP read ? ]
[- OTP read/write ? ]
Indeed, some SPI flash controller drivers need this information.
For instance the Atmel QSPI controller has some optional feature that allow
to scramble data on the fly from/to the (Q)SPI memory. Hence the scrambling
should be enabled for memory {read,write} (Fast Read, Page Programm)
commands but disabled for register {read,write} commands (Read ID, Write
Enable, Read/Write Status Register, ...).
SPI flash controller drivers *should not* have to check the SPI flash command
instruction op code to guess what kind of operation is being performed.
Another example:
Some (Q)SPI flash controllers map the the SPI flash memory into the system
address space then perform some "memcpy-like" operations to access this SPI
flash memory whereas they rely on reguler register to handle SPI flash
commands reading from or writing into the internal registers fo the SPI
flash. So those controller too need to make the difference between register
and memory operations.
Best regards,
Cyrille
> +};
> +
> +#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);
> +};
> +
> +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);
> +
> +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);
> +
> +/**
> + * 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);
> +};
> +
> +int spi_mem_driver_register_with_owner(struct spi_mem_driver *drv,
> + struct module *owner);
> +
> +#define spi_mem_driver_register(__drv) \
> + spi_mem_driver_register_with_owner(__drv, THIS_MODULE)
> +
> +void spi_mem_driver_unregister(struct spi_mem_driver *drv);
> +
> +#define module_spi_mem_driver(__drv) \
> + module_driver(__drv, spi_mem_driver_register, \
> + spi_mem_driver_unregister)
> +
> +/*---------------------------------------------------------------------------*/
> +
> /*
> * INTERFACE between board init code and SPI infrastructure.
> *
>
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