diff --git a/drivers/mtd/spi-mem/spi_mem.c b/drivers/mtd/spi-mem/spi_mem.c new file mode 100644 index 0000000..63ea769 --- /dev/null +++ b/drivers/mtd/spi-mem/spi_mem.c @@ -0,0 +1,288 @@ +/* + * Copyright (c) 2019, STMicroelectronics - All Rights Reserved + * + * SPDX-License-Identifier: BSD-3-Clause + */ + +#include + +#include + +#include +#include + +#define SPI_MEM_DEFAULT_SPEED_HZ 100000U + +/* + * struct spi_slave - Representation of a SPI slave. + * + * @max_hz: Maximum speed for this slave in Hertz. + * @cs: ID of the chip select connected to the slave. + * @mode: SPI mode to use for this slave (see SPI mode flags). + * @ops: Ops defined by the bus. + */ +struct spi_slave { + unsigned int max_hz; + unsigned int cs; + unsigned int mode; + const struct spi_bus_ops *ops; +}; + +static struct spi_slave spi_slave; + +static bool spi_mem_check_buswidth_req(uint8_t buswidth, bool tx) +{ + switch (buswidth) { + case 1U: + return true; + + case 2U: + if ((tx && (spi_slave.mode & (SPI_TX_DUAL | SPI_TX_QUAD)) != + 0U) || + (!tx && (spi_slave.mode & (SPI_RX_DUAL | SPI_RX_QUAD)) != + 0U)) { + return true; + } + break; + + case 4U: + if ((tx && (spi_slave.mode & SPI_TX_QUAD) != 0U) || + (!tx && (spi_slave.mode & SPI_RX_QUAD) != 0U)) { + return true; + } + break; + + default: + break; + } + + return false; +} + +static bool spi_mem_supports_op(const struct spi_mem_op *op) +{ + if (!spi_mem_check_buswidth_req(op->cmd.buswidth, true)) { + return false; + } + + if ((op->addr.nbytes != 0U) && + !spi_mem_check_buswidth_req(op->addr.buswidth, true)) { + return false; + } + + if ((op->dummy.nbytes != 0U) && + !spi_mem_check_buswidth_req(op->dummy.buswidth, true)) { + return false; + } + + if ((op->data.nbytes != 0U) && + !spi_mem_check_buswidth_req(op->data.buswidth, + op->data.dir == SPI_MEM_DATA_OUT)) { + return false; + } + + return true; +} + +static int spi_mem_set_speed_mode(void) +{ + const struct spi_bus_ops *ops = spi_slave.ops; + int ret; + + ret = ops->set_speed(spi_slave.max_hz); + if (ret != 0) { + VERBOSE("Cannot set speed (err=%d)\n", ret); + return ret; + } + + ret = ops->set_mode(spi_slave.mode); + if (ret != 0) { + VERBOSE("Cannot set mode (err=%d)\n", ret); + return ret; + } + + return 0; +} + +static int spi_mem_check_bus_ops(const struct spi_bus_ops *ops) +{ + bool error = false; + + if (ops->claim_bus == NULL) { + VERBOSE("Ops claim bus is not defined\n"); + error = true; + } + + if (ops->release_bus == NULL) { + VERBOSE("Ops release bus is not defined\n"); + error = true; + } + + if (ops->exec_op == NULL) { + VERBOSE("Ops exec op is not defined\n"); + error = true; + } + + if (ops->set_speed == NULL) { + VERBOSE("Ops set speed is not defined\n"); + error = true; + } + + if (ops->set_mode == NULL) { + VERBOSE("Ops set mode is not defined\n"); + error = true; + } + + return error ? -EINVAL : 0; +} + +/* + * spi_mem_exec_op() - Execute a memory operation. + * @op: The memory operation to execute. + * + * 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(const struct spi_mem_op *op) +{ + const struct spi_bus_ops *ops = spi_slave.ops; + int ret; + + VERBOSE("%s: cmd:%x mode:%d.%d.%d.%d addqr:%llx len:%x\n", + __func__, op->cmd.opcode, op->cmd.buswidth, op->addr.buswidth, + op->dummy.buswidth, op->data.buswidth, + op->addr.val, op->data.nbytes); + + if (!spi_mem_supports_op(op)) { + WARN("Error in spi_mem_support\n"); + return -ENOTSUP; + } + + ret = ops->claim_bus(spi_slave.cs); + if (ret != 0) { + WARN("Error claim_bus\n"); + return ret; + } + + ret = ops->exec_op(op); + + ops->release_bus(); + + return ret; +} + +/* + * spi_mem_init_slave() - SPI slave device initialization. + * @fdt: Pointer to the device tree blob. + * @bus_node: Offset of the bus node. + * @ops: The SPI bus ops defined. + * + * This function first checks that @ops are supported and then tries to find + * a SPI slave device. + * + * Return: 0 in case of success, a negative error code otherwise. + */ +int spi_mem_init_slave(void *fdt, int bus_node, const struct spi_bus_ops *ops) +{ + int ret; + int mode = 0; + int nchips = 0; + int bus_subnode = 0; + const fdt32_t *cuint = NULL; + + ret = spi_mem_check_bus_ops(ops); + if (ret != 0) { + return ret; + } + + fdt_for_each_subnode(bus_subnode, fdt, bus_node) { + nchips++; + } + + if (nchips != 1) { + ERROR("Only one SPI device is currently supported\n"); + return -EINVAL; + } + + fdt_for_each_subnode(bus_subnode, fdt, bus_node) { + /* Get chip select */ + cuint = fdt_getprop(fdt, bus_subnode, "reg", NULL); + if (cuint == NULL) { + ERROR("Chip select not well defined\n"); + return -EINVAL; + } + spi_slave.cs = fdt32_to_cpu(*cuint); + + /* Get max slave frequency */ + spi_slave.max_hz = SPI_MEM_DEFAULT_SPEED_HZ; + cuint = fdt_getprop(fdt, bus_subnode, + "spi-max-frequency", NULL); + if (cuint != NULL) { + spi_slave.max_hz = fdt32_to_cpu(*cuint); + } + + /* Get mode */ + if ((fdt_getprop(fdt, bus_subnode, "spi-cpol", NULL)) != NULL) { + mode |= SPI_CPOL; + } + if ((fdt_getprop(fdt, bus_subnode, "spi-cpha", NULL)) != NULL) { + mode |= SPI_CPHA; + } + if ((fdt_getprop(fdt, bus_subnode, "spi-cs-high", NULL)) != + NULL) { + mode |= SPI_CS_HIGH; + } + if ((fdt_getprop(fdt, bus_subnode, "spi-3wire", NULL)) != + NULL) { + mode |= SPI_3WIRE; + } + if ((fdt_getprop(fdt, bus_subnode, "spi-half-duplex", NULL)) != + NULL) { + mode |= SPI_PREAMBLE; + } + + /* Get dual/quad mode */ + cuint = fdt_getprop(fdt, bus_subnode, "spi-tx-bus-width", NULL); + if (cuint != NULL) { + switch (fdt32_to_cpu(*cuint)) { + case 1U: + break; + case 2U: + mode |= SPI_TX_DUAL; + break; + case 4U: + mode |= SPI_TX_QUAD; + break; + default: + WARN("spi-tx-bus-width %d not supported\n", + fdt32_to_cpu(*cuint)); + return -EINVAL; + } + } + + cuint = fdt_getprop(fdt, bus_subnode, "spi-rx-bus-width", NULL); + if (cuint != NULL) { + switch (fdt32_to_cpu(*cuint)) { + case 1U: + break; + case 2U: + mode |= SPI_RX_DUAL; + break; + case 4U: + mode |= SPI_RX_QUAD; + break; + default: + WARN("spi-rx-bus-width %d not supported\n", + fdt32_to_cpu(*cuint)); + return -EINVAL; + } + } + + spi_slave.mode = mode; + spi_slave.ops = ops; + } + + return spi_mem_set_speed_mode(); +} diff --git a/include/drivers/spi_mem.h b/include/drivers/spi_mem.h new file mode 100644 index 0000000..d1953ac --- /dev/null +++ b/include/drivers/spi_mem.h @@ -0,0 +1,130 @@ +/* + * Copyright (c) 2019, STMicroelectronics - All Rights Reserved + * + * SPDX-License-Identifier: BSD-3-Clause + */ + +#ifndef DRIVERS_SPI_MEM_H +#define DRIVERS_SPI_MEM_H + +#include +#include +#include + +#define SPI_MEM_BUSWIDTH_1_LINE 1U +#define SPI_MEM_BUSWIDTH_2_LINE 2U +#define SPI_MEM_BUSWIDTH_4_LINE 4U + +/* + * 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 to 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. + * @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 lines used to transmit the dummy bytes. + * @data.buswidth: Number of IO lines used to send/receive the data. + * @data.dir: Direction of the transfer. + * @data.nbytes: Number of data bytes to transfer. + * @data.buf: Input or output data buffer depending on data::dir. + */ +struct spi_mem_op { + struct { + uint8_t buswidth; + uint8_t opcode; + } cmd; + + struct { + uint8_t nbytes; + uint8_t buswidth; + uint64_t val; + } addr; + + struct { + uint8_t nbytes; + uint8_t buswidth; + } dummy; + + struct { + uint8_t buswidth; + enum spi_mem_data_dir dir; + unsigned int nbytes; + void *buf; + } data; +}; + +/* SPI mode flags */ +#define SPI_CPHA BIT(0) /* clock phase */ +#define SPI_CPOL BIT(1) /* clock polarity */ +#define SPI_CS_HIGH BIT(2) /* CS active high */ +#define SPI_LSB_FIRST BIT(3) /* per-word bits-on-wire */ +#define SPI_3WIRE BIT(4) /* SI/SO signals shared */ +#define SPI_PREAMBLE BIT(5) /* Skip preamble bytes */ +#define SPI_TX_DUAL BIT(6) /* transmit with 2 wires */ +#define SPI_TX_QUAD BIT(7) /* transmit with 4 wires */ +#define SPI_RX_DUAL BIT(8) /* receive with 2 wires */ +#define SPI_RX_QUAD BIT(9) /* receive with 4 wires */ + +struct spi_bus_ops { + /* + * Claim the bus and prepare it for communication. + * + * @cs: The chip select. + * Returns: 0 if the bus was claimed successfully, or a negative value + * if it wasn't. + */ + int (*claim_bus)(unsigned int cs); + + /* + * Release the SPI bus. + */ + void (*release_bus)(void); + + /* + * Set transfer speed. + * + * @hz: The transfer speed in Hertz. + * Returns: 0 on success, a negative error code otherwise. + */ + int (*set_speed)(unsigned int hz); + + /* + * Set the SPI mode/flags. + * + * @mode: Requested SPI mode (SPI_... flags). + * Returns: 0 on success, a negative error code otherwise. + */ + int (*set_mode)(unsigned int mode); + + /* + * Execute a SPI memory operation. + * + * @op: The memory operation to execute. + * Returns: 0 on success, a negative error code otherwise. + */ + int (*exec_op)(const struct spi_mem_op *op); +}; + +int spi_mem_exec_op(const struct spi_mem_op *op); +int spi_mem_init_slave(void *fdt, int bus_node, + const struct spi_bus_ops *ops); + +#endif /* DRIVERS_SPI_MEM_H */