mtd: spi-nor: atmel-quadspi: Add spi-mem support to atmel-quadspi

This patch adds new interface to existing driver. New code is not used yet,
it will be enabled later.
Changes are prepared in small steps to keep patches readable.
Suggested-by: Boris Brezillon <boris.brezillon@bootlin.com>
Signed-off-by: Piotr Bugalski <bugalski.piotr@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/mtd/spi-nor/atmel-quadspi.c

@@ -2,8 +2,10 @@
  * Driver for Atmel QSPI Controller
  *
  * Copyright (C) 2015 Atmel Corporation
+ * Copyright (C) 2018 Cryptera A/S
  *
  * Author: Cyrille Pitchen <cyrille.pitchen@atmel.com>
+ * Author: Piotr Bugalski <bugalski.piotr@gmail.com>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
@@ -35,6 +37,7 @@
 
 #include <linux/io.h>
 #include <linux/gpio/consumer.h>
+#include <linux/spi/spi-mem.h>
 
 /* QSPI register offsets */
 #define QSPI_CR      0x0000  /* Control Register */
@@ -186,6 +189,23 @@ struct atmel_qspi_command {
 	void		*rx_buf;
 };
 
+struct qspi_mode {
+	u8 cmd_buswidth;
+	u8 addr_buswidth;
+	u8 data_buswidth;
+	u32 config;
+};
+
+static const struct qspi_mode sama5d2_qspi_modes[] = {
+	{ 1, 1, 1, QSPI_IFR_WIDTH_SINGLE_BIT_SPI },
+	{ 1, 1, 2, QSPI_IFR_WIDTH_DUAL_OUTPUT },
+	{ 1, 1, 4, QSPI_IFR_WIDTH_QUAD_OUTPUT },
+	{ 1, 2, 2, QSPI_IFR_WIDTH_DUAL_IO },
+	{ 1, 4, 4, QSPI_IFR_WIDTH_QUAD_IO },
+	{ 2, 2, 2, QSPI_IFR_WIDTH_DUAL_CMD },
+	{ 4, 4, 4, QSPI_IFR_WIDTH_QUAD_CMD },
+};
+
 /* Register access functions */
 static inline u32 qspi_readl(struct atmel_qspi *aq, u32 reg)
 {
@@ -197,6 +217,196 @@ static inline void qspi_writel(struct atmel_qspi *aq, u32 reg, u32 value)
 	writel_relaxed(value, aq->regs + reg);
 }
 
+static inline bool is_compatible(const struct spi_mem_op *op,
+				 const struct qspi_mode *mode)
+{
+	if (op->cmd.buswidth != mode->cmd_buswidth)
+		return false;
+
+	if (op->addr.nbytes && op->addr.buswidth != mode->addr_buswidth)
+		return false;
+
+	if (op->data.nbytes && op->data.buswidth != mode->data_buswidth)
+		return false;
+
+	return true;
+}
+
+static int find_mode(const struct spi_mem_op *op)
+{
+	u32 i;
+
+	for (i = 0; i < ARRAY_SIZE(sama5d2_qspi_modes); i++)
+		if (is_compatible(op, &sama5d2_qspi_modes[i]))
+			return i;
+
+	return -1;
+}
+
+static bool atmel_qspi_supports_op(struct spi_mem *mem,
+				   const struct spi_mem_op *op)
+{
+	if (find_mode(op) < 0)
+		return false;
+
+	/* special case not supported by hardware */
+	if (op->addr.nbytes == 2 && op->cmd.buswidth != op->addr.buswidth &&
+		op->dummy.nbytes == 0)
+		return false;
+
+	return true;
+}
+
+static int atmel_qspi_exec_op(struct spi_mem *mem, const struct spi_mem_op *op)
+{
+	struct atmel_qspi *aq = spi_controller_get_devdata(mem->spi->master);
+	int mode;
+	u32 dummy_cycles = 0;
+	u32 iar, icr, ifr, sr;
+	int err = 0;
+
+	iar = 0;
+	icr = QSPI_ICR_INST(op->cmd.opcode);
+	ifr = QSPI_IFR_INSTEN;
+
+	qspi_writel(aq, QSPI_MR, QSPI_MR_SMM);
+
+	mode = find_mode(op);
+	if (mode < 0)
+		return -ENOTSUPP;
+
+	ifr |= sama5d2_qspi_modes[mode].config;
+
+	if (op->dummy.buswidth && op->dummy.nbytes)
+		dummy_cycles = op->dummy.nbytes * 8 / op->dummy.buswidth;
+
+	if (op->addr.buswidth) {
+		switch (op->addr.nbytes) {
+		case 0:
+			break;
+		case 1:
+			ifr |= QSPI_IFR_OPTEN | QSPI_IFR_OPTL_8BIT;
+			icr |= QSPI_ICR_OPT(op->addr.val & 0xff);
+			break;
+		case 2:
+			if (dummy_cycles < 8 / op->addr.buswidth) {
+				ifr &= ~QSPI_IFR_INSTEN;
+				ifr |= QSPI_IFR_ADDREN;
+				iar = (op->cmd.opcode << 16) |
+					(op->addr.val & 0xffff);
+			} else {
+				ifr |= QSPI_IFR_ADDREN;
+				iar = (op->addr.val << 8) & 0xffffff;
+				dummy_cycles -= 8 / op->addr.buswidth;
+			}
+			break;
+		case 3:
+			ifr |= QSPI_IFR_ADDREN;
+			iar = op->addr.val & 0xffffff;
+			break;
+		case 4:
+			ifr |= QSPI_IFR_ADDREN | QSPI_IFR_ADDRL;
+			iar = op->addr.val & 0x7ffffff;
+			break;
+		default:
+			return -ENOTSUPP;
+		}
+	}
+
+	/* Set number of dummy cycles */
+	if (dummy_cycles)
+		ifr |= QSPI_IFR_NBDUM(dummy_cycles);
+
+	/* Set data enable */
+	if (op->data.nbytes)
+		ifr |= QSPI_IFR_DATAEN;
+
+	if (op->data.dir == SPI_MEM_DATA_IN && op->data.nbytes)
+		ifr |= QSPI_IFR_TFRTYP_TRSFR_READ;
+	else
+		ifr |= QSPI_IFR_TFRTYP_TRSFR_WRITE;
+
+	/* Clear pending interrupts */
+	(void)qspi_readl(aq, QSPI_SR);
+
+	/* Set QSPI Instruction Frame registers */
+	qspi_writel(aq, QSPI_IAR, iar);
+	qspi_writel(aq, QSPI_ICR, icr);
+	qspi_writel(aq, QSPI_IFR, ifr);
+
+	/* Skip to the final steps if there is no data */
+	if (op->data.nbytes) {
+		/* Dummy read of QSPI_IFR to synchronize APB and AHB accesses */
+		(void)qspi_readl(aq, QSPI_IFR);
+
+		/* Send/Receive data */
+		if (op->data.dir == SPI_MEM_DATA_IN)
+			_memcpy_fromio(op->data.buf.in,
+				aq->mem + iar, op->data.nbytes);
+		else
+			_memcpy_toio(aq->mem + iar,
+				op->data.buf.out, op->data.nbytes);
+
+		/* Release the chip-select */
+		qspi_writel(aq, QSPI_CR, QSPI_CR_LASTXFER);
+	}
+
+	/* Poll INSTRuction End status */
+	sr = qspi_readl(aq, QSPI_SR);
+	if ((sr & QSPI_SR_CMD_COMPLETED) == QSPI_SR_CMD_COMPLETED)
+		return err;
+
+	/* Wait for INSTRuction End interrupt */
+	reinit_completion(&aq->cmd_completion);
+	aq->pending = sr & QSPI_SR_CMD_COMPLETED;
+	qspi_writel(aq, QSPI_IER, QSPI_SR_CMD_COMPLETED);
+	if (!wait_for_completion_timeout(&aq->cmd_completion,
+					 msecs_to_jiffies(1000)))
+		err = -ETIMEDOUT;
+	qspi_writel(aq, QSPI_IDR, QSPI_SR_CMD_COMPLETED);
+
+	return err;
+}
+
+const char *atmel_qspi_get_name(struct spi_mem *spimem)
+{
+	return dev_name(spimem->spi->dev.parent);
+}
+
+static const struct spi_controller_mem_ops atmel_qspi_mem_ops = {
+	.supports_op = atmel_qspi_supports_op,
+	.exec_op = atmel_qspi_exec_op,
+	.get_name = atmel_qspi_get_name
+};
+
+static int atmel_qspi_setup(struct spi_device *spi)
+{
+	struct spi_controller *ctrl = spi->master;
+	struct atmel_qspi *aq = spi_controller_get_devdata(ctrl);
+	unsigned long src_rate;
+	u32 scr, scbr;
+
+	if (ctrl->busy)
+		return -EBUSY;
+
+	if (!spi->max_speed_hz)
+		return -EINVAL;
+
+	src_rate = clk_get_rate(aq->clk);
+	if (!src_rate)
+		return -EINVAL;
+
+	/* Compute the QSPI baudrate */
+	scbr = DIV_ROUND_UP(src_rate, spi->max_speed_hz);
+	if (scbr > 0)
+		scbr--;
+
+	scr = QSPI_SCR_SCBR(scbr);
+	qspi_writel(aq, QSPI_SCR, scr);
+
+	return 0;
+}
+
 static int atmel_qspi_run_transfer(struct atmel_qspi *aq,
 				   const struct atmel_qspi_command *cmd)
 {
@@ -777,5 +987,6 @@ static struct platform_driver atmel_qspi_driver = {
 module_platform_driver(atmel_qspi_driver);
 
 MODULE_AUTHOR("Cyrille Pitchen <cyrille.pitchen@atmel.com>");
+MODULE_AUTHOR("Piotr Bugalski <bugalski.piotr@gmail.com");
 MODULE_DESCRIPTION("Atmel QSPI Controller driver");
 MODULE_LICENSE("GPL v2");