Add SPI-MEM framework

This framework supports SPI operations using a common
spi_mem_op structure:
 - command
 - addr
 - dummy
 - data

The framework manages SPI bus configuration:
 - speed
 - bus width (Up to quad mode)
 - chip select

Change-Id: Idc2736c59bfc5ac6e55429eba5d385275ea3fbde
Signed-off-by: Lionel Debieve <lionel.debieve@st.com>
Signed-off-by: Christophe Kerello <christophe.kerello@st.com>

drivers/mtd/spi-mem/spi_mem.c

+/*
+ * Copyright (c) 2019, STMicroelectronics - All Rights Reserved
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <assert.h>
+
+#include <libfdt.h>
+
+#include <drivers/spi_mem.h>
+#include <lib/utils_def.h>
+
+#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();
+}

include/drivers/spi_mem.h

+/*
+ * Copyright (c) 2019, STMicroelectronics - All Rights Reserved
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#ifndef DRIVERS_SPI_MEM_H
+#define DRIVERS_SPI_MEM_H
+
+#include <errno.h>
+#include <stdbool.h>
+#include <stdint.h>
+
+#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 */