[RFC PATCH v2 2/6] mtd: spi-nor: atmel-quadspi: Add spi-mem support to atmel-quadspi

[Piotr Bugalski <bugalski.piotr@gmail.com>]

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 <pbu@cryptera.com>
---
 drivers/mtd/spi-nor/atmel-quadspi.c | 205 ++++++++++++++++++++++++++++++++++++
 1 file changed, 205 insertions(+)

diff --git a/drivers/mtd/spi-nor/atmel-quadspi.c b/drivers/mtd/spi-nor/atmel-quadspi.c
index bdbfaa632dbf..c36fcecd569a 100644
--- a/drivers/mtd/spi-nor/atmel-quadspi.c
+++ b/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 <pbu@cryptera.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.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 +217,190 @@ 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;
+}
+
+static const struct spi_controller_mem_ops atmel_qspi_mem_ops = {
+	.supports_op = atmel_qspi_supports_op,
+	.exec_op = atmel_qspi_exec_op
+};
+
+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)
 {
@@ -756,5 +960,6 @@ 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 <pbu@cryptera.com");
 MODULE_DESCRIPTION("Atmel QSPI Controller driver");
 MODULE_LICENSE("GPL v2");
-- 
2.11.0