diff options
Diffstat (limited to 'drivers/spi/spi-mem.c')
| -rw-r--r-- | drivers/spi/spi-mem.c | 524 |
1 files changed, 524 insertions, 0 deletions
diff --git a/drivers/spi/spi-mem.c b/drivers/spi/spi-mem.c new file mode 100644 index 0000000000..b438ed3dcc --- /dev/null +++ b/drivers/spi/spi-mem.c @@ -0,0 +1,524 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * Copyright (C) 2018 Exceet Electronics GmbH + * Copyright (C) 2018 Bootlin + * + * Author: Boris Brezillon <boris.brezillon@bootlin.com> + */ +#include <common.h> +#include <module.h> +#include <linux/kernel.h> +#include <linux/spi/spi-mem.h> +#include <spi/spi.h> + +#define SPI_MEM_MAX_BUSWIDTH 8 + +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; + + case 8: + if ((tx && (mode & SPI_TX_OCTAL)) || + (!tx && (mode & SPI_RX_OCTAL))) + 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.dir != SPI_MEM_NO_DATA && + 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); + +static bool spi_mem_buswidth_is_valid(u8 buswidth) +{ + if (hweight8(buswidth) > 1 || buswidth > SPI_MEM_MAX_BUSWIDTH) + return false; + + return true; +} + +static int spi_mem_check_op(const struct spi_mem_op *op) +{ + if (!op->cmd.buswidth) + return -EINVAL; + + if ((op->addr.nbytes && !op->addr.buswidth) || + (op->dummy.nbytes && !op->dummy.buswidth) || + (op->data.nbytes && !op->data.buswidth)) + return -EINVAL; + + if (!spi_mem_buswidth_is_valid(op->cmd.buswidth) || + !spi_mem_buswidth_is_valid(op->addr.buswidth) || + !spi_mem_buswidth_is_valid(op->dummy.buswidth) || + !spi_mem_buswidth_is_valid(op->data.buswidth)) + return -EINVAL; + + return 0; +} + +static bool spi_mem_internal_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); +} + +/** + * 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) +{ + if (spi_mem_check_op(op)) + return false; + + return spi_mem_internal_supports_op(mem, op); +} +EXPORT_SYMBOL_GPL(spi_mem_supports_op); + +static int spi_mem_access_start(struct spi_mem *mem) +{ + return 0; +} + +static void spi_mem_access_end(struct spi_mem *mem) +{ + return; +} + +/** + * 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; + + ret = spi_mem_check_op(op); + if (ret) + return ret; + + if (!spi_mem_internal_supports_op(mem, op)) + return -ENOTSUPP; + + if (ctlr->mem_ops) { + ret = spi_mem_access_start(mem); + if (ret) + return ret; + + ret = ctlr->mem_ops->exec_op(mem, op); + + spi_mem_access_end(mem); + + /* + * 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); + 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); + 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; + 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; + 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; + else + xfers[xferpos].tx_buf = op->data.buf.out; + + 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_get_name() - Return the SPI mem device name to be used by the + * upper layer if necessary + * @mem: the SPI memory + * + * This function allows SPI mem users to retrieve the SPI mem device name. + * It is useful if the upper layer needs to expose a custom name for + * compatibility reasons. + * + * Return: a string containing the name of the memory device to be used + * by the SPI mem user + */ +const char *spi_mem_get_name(struct spi_mem *mem) +{ + return mem->name; +} +EXPORT_SYMBOL_GPL(spi_mem_get_name); + +/** + * 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; + size_t len; + + len = sizeof(op->cmd.opcode) + op->addr.nbytes + op->dummy.nbytes; + + if (ctlr->mem_ops && ctlr->mem_ops->adjust_op_size) + return ctlr->mem_ops->adjust_op_size(mem, op); + + if (!ctlr->mem_ops || !ctlr->mem_ops->exec_op) { + if (len > spi_max_transfer_size(mem->spi)) + return -EINVAL; + + op->data.nbytes = min3((size_t)op->data.nbytes, + spi_max_transfer_size(mem->spi), + spi_max_message_size(mem->spi) - + len); + if (!op->data.nbytes) + return -EINVAL; + } + + return 0; +} +EXPORT_SYMBOL_GPL(spi_mem_adjust_op_size); + +static ssize_t spi_mem_no_dirmap_read(struct spi_mem_dirmap_desc *desc, + u64 offs, size_t len, void *buf) +{ + struct spi_mem_op op = desc->info.op_tmpl; + int ret; + + op.addr.val = desc->info.offset + offs; + op.data.buf.in = buf; + op.data.nbytes = len; + ret = spi_mem_adjust_op_size(desc->mem, &op); + if (ret) + return ret; + + ret = spi_mem_exec_op(desc->mem, &op); + if (ret) + return ret; + + return op.data.nbytes; +} + +static ssize_t spi_mem_no_dirmap_write(struct spi_mem_dirmap_desc *desc, + u64 offs, size_t len, const void *buf) +{ + struct spi_mem_op op = desc->info.op_tmpl; + int ret; + + op.addr.val = desc->info.offset + offs; + op.data.buf.out = buf; + op.data.nbytes = len; + ret = spi_mem_adjust_op_size(desc->mem, &op); + if (ret) + return ret; + + ret = spi_mem_exec_op(desc->mem, &op); + if (ret) + return ret; + + return op.data.nbytes; +} + +/** + * spi_mem_dirmap_create() - Create a direct mapping descriptor + * @mem: SPI mem device this direct mapping should be created for + * @info: direct mapping information + * + * This function is creating a direct mapping descriptor which can then be used + * to access the memory using spi_mem_dirmap_read() or spi_mem_dirmap_write(). + * If the SPI controller driver does not support direct mapping, this function + * fallback to an implementation using spi_mem_exec_op(), so that the caller + * doesn't have to bother implementing a fallback on his own. + * + * Return: a valid pointer in case of success, and ERR_PTR() otherwise. + */ +struct spi_mem_dirmap_desc * +spi_mem_dirmap_create(struct spi_mem *mem, + const struct spi_mem_dirmap_info *info) +{ + struct spi_controller *ctlr = mem->spi->controller; + struct spi_mem_dirmap_desc *desc; + int ret = -ENOTSUPP; + + /* Make sure the number of address cycles is between 1 and 8 bytes. */ + if (!info->op_tmpl.addr.nbytes || info->op_tmpl.addr.nbytes > 8) + return ERR_PTR(-EINVAL); + + /* data.dir should either be SPI_MEM_DATA_IN or SPI_MEM_DATA_OUT. */ + if (info->op_tmpl.data.dir == SPI_MEM_NO_DATA) + return ERR_PTR(-EINVAL); + + desc = kzalloc(sizeof(*desc), GFP_KERNEL); + if (!desc) + return ERR_PTR(-ENOMEM); + + desc->mem = mem; + desc->info = *info; + if (ctlr->mem_ops && ctlr->mem_ops->dirmap_create) + ret = ctlr->mem_ops->dirmap_create(desc); + + if (ret) { + desc->nodirmap = true; + if (!spi_mem_supports_op(desc->mem, &desc->info.op_tmpl)) + ret = -ENOTSUPP; + else + ret = 0; + } + + if (ret) { + kfree(desc); + return ERR_PTR(ret); + } + + return desc; +} +EXPORT_SYMBOL_GPL(spi_mem_dirmap_create); + +/** + * spi_mem_dirmap_destroy() - Destroy a direct mapping descriptor + * @desc: the direct mapping descriptor to destroy + * @info: direct mapping information + * + * This function destroys a direct mapping descriptor previously created by + * spi_mem_dirmap_create(). + */ +void spi_mem_dirmap_destroy(struct spi_mem_dirmap_desc *desc) +{ + struct spi_controller *ctlr = desc->mem->spi->controller; + + if (!desc->nodirmap && ctlr->mem_ops && ctlr->mem_ops->dirmap_destroy) + ctlr->mem_ops->dirmap_destroy(desc); +} +EXPORT_SYMBOL_GPL(spi_mem_dirmap_destroy); + +/** + * spi_mem_dirmap_dirmap_read() - Read data through a direct mapping + * @desc: direct mapping descriptor + * @offs: offset to start reading from. Note that this is not an absolute + * offset, but the offset within the direct mapping which already has + * its own offset + * @len: length in bytes + * @buf: destination buffer. This buffer must be DMA-able + * + * This function reads data from a memory device using a direct mapping + * previously instantiated with spi_mem_dirmap_create(). + * + * Return: the amount of data read from the memory device or a negative error + * code. Note that the returned size might be smaller than @len, and the caller + * is responsible for calling spi_mem_dirmap_read() again when that happens. + */ +ssize_t spi_mem_dirmap_read(struct spi_mem_dirmap_desc *desc, + u64 offs, size_t len, void *buf) +{ + struct spi_controller *ctlr = desc->mem->spi->controller; + ssize_t ret; + + if (desc->info.op_tmpl.data.dir != SPI_MEM_DATA_IN) + return -EINVAL; + + if (!len) + return 0; + + if (desc->nodirmap) { + ret = spi_mem_no_dirmap_read(desc, offs, len, buf); + } else if (ctlr->mem_ops && ctlr->mem_ops->dirmap_read) { + ret = spi_mem_access_start(desc->mem); + if (ret) + return ret; + + ret = ctlr->mem_ops->dirmap_read(desc, offs, len, buf); + + spi_mem_access_end(desc->mem); + } else { + ret = -ENOTSUPP; + } + + return ret; +} +EXPORT_SYMBOL_GPL(spi_mem_dirmap_read); + +/** + * spi_mem_dirmap_dirmap_write() - Write data through a direct mapping + * @desc: direct mapping descriptor + * @offs: offset to start writing from. Note that this is not an absolute + * offset, but the offset within the direct mapping which already has + * its own offset + * @len: length in bytes + * @buf: source buffer. This buffer must be DMA-able + * + * This function writes data to a memory device using a direct mapping + * previously instantiated with spi_mem_dirmap_create(). + * + * Return: the amount of data written to the memory device or a negative error + * code. Note that the returned size might be smaller than @len, and the caller + * is responsible for calling spi_mem_dirmap_write() again when that happens. + */ +ssize_t spi_mem_dirmap_write(struct spi_mem_dirmap_desc *desc, + u64 offs, size_t len, const void *buf) +{ + struct spi_controller *ctlr = desc->mem->spi->controller; + ssize_t ret; + + if (desc->info.op_tmpl.data.dir != SPI_MEM_DATA_OUT) + return -EINVAL; + + if (!len) + return 0; + + if (desc->nodirmap) { + ret = spi_mem_no_dirmap_write(desc, offs, len, buf); + } else if (ctlr->mem_ops && ctlr->mem_ops->dirmap_write) { + ret = spi_mem_access_start(desc->mem); + if (ret) + return ret; + + ret = ctlr->mem_ops->dirmap_write(desc, offs, len, buf); + + spi_mem_access_end(desc->mem); + } else { + ret = -ENOTSUPP; + } + + return ret; +} +EXPORT_SYMBOL_GPL(spi_mem_dirmap_write); |