Merge tag 'mtk-mtd-spi-move' of https://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi into spi-5.7

spi: Rewrite mtk-quadspi spi-nor driver with spi-mem

This patchset from Chuanhong Guo <gch981213@gmail.com> adds a spi-mem
driver for Mediatek SPI-NOR controller, which already has limited
support by mtk-quadspi. This new driver can make use of full quadspi
capability of this controller.

4 files changed, 702 insertions, 7 deletions

diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index ad79454d8584..c33ca96b44de 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -456,6 +456,16 @@ config SPI_MT7621
 	help
 	  This selects a driver for the MediaTek MT7621 SPI Controller.
 
+config SPI_MTK_NOR
+	tristate "MediaTek SPI NOR controller"
+	depends on ARCH_MEDIATEK || COMPILE_TEST
+	help
+	  This enables support for SPI NOR controller found on MediaTek
+	  ARM SoCs. This is a controller specifically for SPI-NOR flash.
+	  It can perform generic SPI transfers up to 6 bytes via generic
+	  SPI interface as well as several SPI-NOR specific instructions
+	  via SPI MEM interface.
+
 config SPI_NPCM_FIU
 	tristate "Nuvoton NPCM FLASH Interface Unit"
 	depends on ARCH_NPCM || COMPILE_TEST
diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
index aba824a2c447..28f601327f8c 100644
--- a/drivers/spi/Makefile
+++ b/drivers/spi/Makefile
@@ -65,6 +65,7 @@ obj-$(CONFIG_SPI_MPC52xx_PSC)		+= spi-mpc52xx-psc.o
 obj-$(CONFIG_SPI_MPC52xx)		+= spi-mpc52xx.o
 obj-$(CONFIG_SPI_MT65XX)                += spi-mt65xx.o
 obj-$(CONFIG_SPI_MT7621)		+= spi-mt7621.o
+obj-$(CONFIG_SPI_MTK_NOR)		+= spi-mtk-nor.o
 obj-$(CONFIG_SPI_MXIC)			+= spi-mxic.o
 obj-$(CONFIG_SPI_MXS)			+= spi-mxs.o
 obj-$(CONFIG_SPI_NPCM_FIU)		+= spi-npcm-fiu.o
diff --git a/drivers/spi/spi-mtk-nor.c b/drivers/spi/spi-mtk-nor.c
new file mode 100644
index 000000000000..c15a9910549f
--- /dev/null
+++ b/drivers/spi/spi-mtk-nor.c
@@ -0,0 +1,689 @@
+// SPDX-License-Identifier: GPL-2.0
+//
+// Mediatek SPI NOR controller driver
+//
+// Copyright (C) 2020 Chuanhong Guo <gch981213@gmail.com>
+
+#include <linux/bits.h>
+#include <linux/clk.h>
+#include <linux/completion.h>
+#include <linux/dma-mapping.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/iopoll.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/spi/spi.h>
+#include <linux/spi/spi-mem.h>
+#include <linux/string.h>
+
+#define DRIVER_NAME "mtk-spi-nor"
+
+#define MTK_NOR_REG_CMD			0x00
+#define MTK_NOR_CMD_WRITE		BIT(4)
+#define MTK_NOR_CMD_PROGRAM		BIT(2)
+#define MTK_NOR_CMD_READ		BIT(0)
+#define MTK_NOR_CMD_MASK		GENMASK(5, 0)
+
+#define MTK_NOR_REG_PRG_CNT		0x04
+#define MTK_NOR_REG_RDATA		0x0c
+
+#define MTK_NOR_REG_RADR0		0x10
+#define MTK_NOR_REG_RADR(n)		(MTK_NOR_REG_RADR0 + 4 * (n))
+#define MTK_NOR_REG_RADR3		0xc8
+
+#define MTK_NOR_REG_WDATA		0x1c
+
+#define MTK_NOR_REG_PRGDATA0		0x20
+#define MTK_NOR_REG_PRGDATA(n)		(MTK_NOR_REG_PRGDATA0 + 4 * (n))
+#define MTK_NOR_REG_PRGDATA_MAX		5
+
+#define MTK_NOR_REG_SHIFT0		0x38
+#define MTK_NOR_REG_SHIFT(n)		(MTK_NOR_REG_SHIFT0 + 4 * (n))
+#define MTK_NOR_REG_SHIFT_MAX		9
+
+#define MTK_NOR_REG_CFG1		0x60
+#define MTK_NOR_FAST_READ		BIT(0)
+
+#define MTK_NOR_REG_CFG2		0x64
+#define MTK_NOR_WR_CUSTOM_OP_EN		BIT(4)
+#define MTK_NOR_WR_BUF_EN		BIT(0)
+
+#define MTK_NOR_REG_PP_DATA		0x98
+
+#define MTK_NOR_REG_IRQ_STAT		0xa8
+#define MTK_NOR_REG_IRQ_EN		0xac
+#define MTK_NOR_IRQ_DMA			BIT(7)
+#define MTK_NOR_IRQ_MASK		GENMASK(7, 0)
+
+#define MTK_NOR_REG_CFG3		0xb4
+#define MTK_NOR_DISABLE_WREN		BIT(7)
+#define MTK_NOR_DISABLE_SR_POLL		BIT(5)
+
+#define MTK_NOR_REG_WP			0xc4
+#define MTK_NOR_ENABLE_SF_CMD		0x30
+
+#define MTK_NOR_REG_BUSCFG		0xcc
+#define MTK_NOR_4B_ADDR			BIT(4)
+#define MTK_NOR_QUAD_ADDR		BIT(3)
+#define MTK_NOR_QUAD_READ		BIT(2)
+#define MTK_NOR_DUAL_ADDR		BIT(1)
+#define MTK_NOR_DUAL_READ		BIT(0)
+#define MTK_NOR_BUS_MODE_MASK		GENMASK(4, 0)
+
+#define MTK_NOR_REG_DMA_CTL		0x718
+#define MTK_NOR_DMA_START		BIT(0)
+
+#define MTK_NOR_REG_DMA_FADR		0x71c
+#define MTK_NOR_REG_DMA_DADR		0x720
+#define MTK_NOR_REG_DMA_END_DADR	0x724
+
+#define MTK_NOR_PRG_MAX_SIZE		6
+// Reading DMA src/dst addresses have to be 16-byte aligned
+#define MTK_NOR_DMA_ALIGN		16
+#define MTK_NOR_DMA_ALIGN_MASK		(MTK_NOR_DMA_ALIGN - 1)
+// and we allocate a bounce buffer if destination address isn't aligned.
+#define MTK_NOR_BOUNCE_BUF_SIZE		PAGE_SIZE
+
+// Buffered page program can do one 128-byte transfer
+#define MTK_NOR_PP_SIZE			128
+
+#define CLK_TO_US(sp, clkcnt)		((clkcnt) * 1000000 / sp->spi_freq)
+
+struct mtk_nor {
+	struct spi_controller *ctlr;
+	struct device *dev;
+	void __iomem *base;
+	u8 *buffer;
+	struct clk *spi_clk;
+	struct clk *ctlr_clk;
+	unsigned int spi_freq;
+	bool wbuf_en;
+	bool has_irq;
+	struct completion op_done;
+};
+
+static inline void mtk_nor_rmw(struct mtk_nor *sp, u32 reg, u32 set, u32 clr)
+{
+	u32 val = readl(sp->base + reg);
+
+	val &= ~clr;
+	val |= set;
+	writel(val, sp->base + reg);
+}
+
+static inline int mtk_nor_cmd_exec(struct mtk_nor *sp, u32 cmd, ulong clk)
+{
+	ulong delay = CLK_TO_US(sp, clk);
+	u32 reg;
+	int ret;
+
+	writel(cmd, sp->base + MTK_NOR_REG_CMD);
+	ret = readl_poll_timeout(sp->base + MTK_NOR_REG_CMD, reg, !(reg & cmd),
+				 delay / 3, (delay + 1) * 200);
+	if (ret < 0)
+		dev_err(sp->dev, "command %u timeout.\n", cmd);
+	return ret;
+}
+
+static void mtk_nor_set_addr(struct mtk_nor *sp, const struct spi_mem_op *op)
+{
+	u32 addr = op->addr.val;
+	int i;
+
+	for (i = 0; i < 3; i++) {
+		writeb(addr & 0xff, sp->base + MTK_NOR_REG_RADR(i));
+		addr >>= 8;
+	}
+	if (op->addr.nbytes == 4) {
+		writeb(addr & 0xff, sp->base + MTK_NOR_REG_RADR3);
+		mtk_nor_rmw(sp, MTK_NOR_REG_BUSCFG, MTK_NOR_4B_ADDR, 0);
+	} else {
+		mtk_nor_rmw(sp, MTK_NOR_REG_BUSCFG, 0, MTK_NOR_4B_ADDR);
+	}
+}
+
+static bool mtk_nor_match_read(const struct spi_mem_op *op)
+{
+	int dummy = 0;
+
+	if (op->dummy.buswidth)
+		dummy = op->dummy.nbytes * BITS_PER_BYTE / op->dummy.buswidth;
+
+	if ((op->data.buswidth == 2) || (op->data.buswidth == 4)) {
+		if (op->addr.buswidth == 1)
+			return dummy == 8;
+		else if (op->addr.buswidth == 2)
+			return dummy == 4;
+		else if (op->addr.buswidth == 4)
+			return dummy == 6;
+	} else if ((op->addr.buswidth == 1) && (op->data.buswidth == 1)) {
+		if (op->cmd.opcode == 0x03)
+			return dummy == 0;
+		else if (op->cmd.opcode == 0x0b)
+			return dummy == 8;
+	}
+	return false;
+}
+
+static int mtk_nor_adjust_op_size(struct spi_mem *mem, struct spi_mem_op *op)
+{
+	size_t len;
+
+	if (!op->data.nbytes)
+		return 0;
+
+	if ((op->addr.nbytes == 3) || (op->addr.nbytes == 4)) {
+		if ((op->data.dir == SPI_MEM_DATA_IN) &&
+		    mtk_nor_match_read(op)) {
+			if ((op->addr.val & MTK_NOR_DMA_ALIGN_MASK) ||
+			    (op->data.nbytes < MTK_NOR_DMA_ALIGN))
+				op->data.nbytes = 1;
+			else if (!((ulong)(op->data.buf.in) &
+				   MTK_NOR_DMA_ALIGN_MASK))
+				op->data.nbytes &= ~MTK_NOR_DMA_ALIGN_MASK;
+			else if (op->data.nbytes > MTK_NOR_BOUNCE_BUF_SIZE)
+				op->data.nbytes = MTK_NOR_BOUNCE_BUF_SIZE;
+			return 0;
+		} else if (op->data.dir == SPI_MEM_DATA_OUT) {
+			if (op->data.nbytes >= MTK_NOR_PP_SIZE)
+				op->data.nbytes = MTK_NOR_PP_SIZE;
+			else
+				op->data.nbytes = 1;
+			return 0;
+		}
+	}
+
+	len = MTK_NOR_PRG_MAX_SIZE - sizeof(op->cmd.opcode) - op->addr.nbytes -
+	      op->dummy.nbytes;
+	if (op->data.nbytes > len)
+		op->data.nbytes = len;
+
+	return 0;
+}
+
+static bool mtk_nor_supports_op(struct spi_mem *mem,
+				const struct spi_mem_op *op)
+{
+	size_t len;
+
+	if (op->cmd.buswidth != 1)
+		return false;
+
+	if ((op->addr.nbytes == 3) || (op->addr.nbytes == 4)) {
+		if ((op->data.dir == SPI_MEM_DATA_IN) && mtk_nor_match_read(op))
+			return true;
+		else if (op->data.dir == SPI_MEM_DATA_OUT)
+			return (op->addr.buswidth == 1) &&
+			       (op->dummy.buswidth == 0) &&
+			       (op->data.buswidth == 1);
+	}
+	len = sizeof(op->cmd.opcode) + op->addr.nbytes + op->dummy.nbytes;
+	if ((len > MTK_NOR_PRG_MAX_SIZE) ||
+	    ((op->data.nbytes) && (len == MTK_NOR_PRG_MAX_SIZE)))
+		return false;
+	return true;
+}
+
+static void mtk_nor_setup_bus(struct mtk_nor *sp, const struct spi_mem_op *op)
+{
+	u32 reg = 0;
+
+	if (op->addr.nbytes == 4)
+		reg |= MTK_NOR_4B_ADDR;
+
+	if (op->data.buswidth == 4) {
+		reg |= MTK_NOR_QUAD_READ;
+		writeb(op->cmd.opcode, sp->base + MTK_NOR_REG_PRGDATA(4));
+		if (op->addr.buswidth == 4)
+			reg |= MTK_NOR_QUAD_ADDR;
+	} else if (op->data.buswidth == 2) {
+		reg |= MTK_NOR_DUAL_READ;
+		writeb(op->cmd.opcode, sp->base + MTK_NOR_REG_PRGDATA(3));
+		if (op->addr.buswidth == 2)
+			reg |= MTK_NOR_DUAL_ADDR;
+	} else {
+		if (op->cmd.opcode == 0x0b)
+			mtk_nor_rmw(sp, MTK_NOR_REG_CFG1, MTK_NOR_FAST_READ, 0);
+		else
+			mtk_nor_rmw(sp, MTK_NOR_REG_CFG1, 0, MTK_NOR_FAST_READ);
+	}
+	mtk_nor_rmw(sp, MTK_NOR_REG_BUSCFG, reg, MTK_NOR_BUS_MODE_MASK);
+}
+
+static int mtk_nor_read_dma(struct mtk_nor *sp, u32 from, unsigned int length,
+			    u8 *buffer)
+{
+	int ret = 0;
+	ulong delay;
+	u32 reg;
+	dma_addr_t dma_addr;
+
+	dma_addr = dma_map_single(sp->dev, buffer, length, DMA_FROM_DEVICE);
+	if (dma_mapping_error(sp->dev, dma_addr)) {
+		dev_err(sp->dev, "failed to map dma buffer.\n");
+		return -EINVAL;
+	}
+
+	writel(from, sp->base + MTK_NOR_REG_DMA_FADR);
+	writel(dma_addr, sp->base + MTK_NOR_REG_DMA_DADR);
+	writel(dma_addr + length, sp->base + MTK_NOR_REG_DMA_END_DADR);
+
+	if (sp->has_irq) {
+		reinit_completion(&sp->op_done);
+		mtk_nor_rmw(sp, MTK_NOR_REG_IRQ_EN, MTK_NOR_IRQ_DMA, 0);
+	}
+
+	mtk_nor_rmw(sp, MTK_NOR_REG_DMA_CTL, MTK_NOR_DMA_START, 0);
+
+	delay = CLK_TO_US(sp, (length + 5) * BITS_PER_BYTE);
+
+	if (sp->has_irq) {
+		if (!wait_for_completion_timeout(&sp->op_done,
+						 (delay + 1) * 100))
+			ret = -ETIMEDOUT;
+	} else {
+		ret = readl_poll_timeout(sp->base + MTK_NOR_REG_DMA_CTL, reg,
+					 !(reg & MTK_NOR_DMA_START), delay / 3,
+					 (delay + 1) * 100);
+	}
+
+	dma_unmap_single(sp->dev, dma_addr, length, DMA_FROM_DEVICE);
+	if (ret < 0)
+		dev_err(sp->dev, "dma read timeout.\n");
+
+	return ret;
+}
+
+static int mtk_nor_read_bounce(struct mtk_nor *sp, u32 from,
+			       unsigned int length, u8 *buffer)
+{
+	unsigned int rdlen;
+	int ret;
+
+	if (length & MTK_NOR_DMA_ALIGN_MASK)
+		rdlen = (length + MTK_NOR_DMA_ALIGN) & ~MTK_NOR_DMA_ALIGN_MASK;
+	else
+		rdlen = length;
+
+	ret = mtk_nor_read_dma(sp, from, rdlen, sp->buffer);
+	if (ret)
+		return ret;
+
+	memcpy(buffer, sp->buffer, length);
+	return 0;
+}
+
+static int mtk_nor_read_pio(struct mtk_nor *sp, const struct spi_mem_op *op)
+{
+	u8 *buf = op->data.buf.in;
+	int ret;
+
+	ret = mtk_nor_cmd_exec(sp, MTK_NOR_CMD_READ, 6 * BITS_PER_BYTE);
+	if (!ret)
+		buf[0] = readb(sp->base + MTK_NOR_REG_RDATA);
+	return ret;
+}
+
+static int mtk_nor_write_buffer_enable(struct mtk_nor *sp)
+{
+	int ret;
+	u32 val;
+
+	if (sp->wbuf_en)
+		return 0;
+
+	val = readl(sp->base + MTK_NOR_REG_CFG2);
+	writel(val | MTK_NOR_WR_BUF_EN, sp->base + MTK_NOR_REG_CFG2);
+	ret = readl_poll_timeout(sp->base + MTK_NOR_REG_CFG2, val,
+				 val & MTK_NOR_WR_BUF_EN, 0, 10000);
+	if (!ret)
+		sp->wbuf_en = true;
+	return ret;
+}
+
+static int mtk_nor_write_buffer_disable(struct mtk_nor *sp)
+{
+	int ret;
+	u32 val;
+
+	if (!sp->wbuf_en)
+		return 0;
+	val = readl(sp->base + MTK_NOR_REG_CFG2);
+	writel(val & ~MTK_NOR_WR_BUF_EN, sp->base + MTK_NOR_REG_CFG2);
+	ret = readl_poll_timeout(sp->base + MTK_NOR_REG_CFG2, val,
+				 !(val & MTK_NOR_WR_BUF_EN), 0, 10000);
+	if (!ret)
+		sp->wbuf_en = false;
+	return ret;
+}
+
+static int mtk_nor_pp_buffered(struct mtk_nor *sp, const struct spi_mem_op *op)
+{
+	const u8 *buf = op->data.buf.out;
+	u32 val;
+	int ret, i;
+
+	ret = mtk_nor_write_buffer_enable(sp);
+	if (ret < 0)
+		return ret;
+
+	for (i = 0; i < op->data.nbytes; i += 4) {
+		val = buf[i + 3] << 24 | buf[i + 2] << 16 | buf[i + 1] << 8 |
+		      buf[i];
+		writel(val, sp->base + MTK_NOR_REG_PP_DATA);
+	}
+	return mtk_nor_cmd_exec(sp, MTK_NOR_CMD_WRITE,
+				(op->data.nbytes + 5) * BITS_PER_BYTE);
+}
+
+static int mtk_nor_pp_unbuffered(struct mtk_nor *sp,
+				 const struct spi_mem_op *op)
+{
+	const u8 *buf = op->data.buf.out;
+	int ret;
+
+	ret = mtk_nor_write_buffer_disable(sp);
+	if (ret < 0)
+		return ret;
+	writeb(buf[0], sp->base + MTK_NOR_REG_WDATA);
+	return mtk_nor_cmd_exec(sp, MTK_NOR_CMD_WRITE, 6 * BITS_PER_BYTE);
+}
+
+int mtk_nor_exec_op(struct spi_mem *mem, const struct spi_mem_op *op)
+{
+	struct mtk_nor *sp = spi_controller_get_devdata(mem->spi->master);
+	int ret;
+
+	if ((op->data.nbytes == 0) ||
+	    ((op->addr.nbytes != 3) && (op->addr.nbytes != 4)))
+		return -ENOTSUPP;
+
+	if (op->data.dir == SPI_MEM_DATA_OUT) {
+		mtk_nor_set_addr(sp, op);
+		writeb(op->cmd.opcode, sp->base + MTK_NOR_REG_PRGDATA0);
+		if (op->data.nbytes == MTK_NOR_PP_SIZE)
+			return mtk_nor_pp_buffered(sp, op);
+		return mtk_nor_pp_unbuffered(sp, op);
+	}
+
+	if ((op->data.dir == SPI_MEM_DATA_IN) && mtk_nor_match_read(op)) {
+		ret = mtk_nor_write_buffer_disable(sp);
+		if (ret < 0)
+			return ret;
+		mtk_nor_setup_bus(sp, op);
+		if (op->data.nbytes == 1) {
+			mtk_nor_set_addr(sp, op);
+			return mtk_nor_read_pio(sp, op);
+		} else if (((ulong)(op->data.buf.in) &
+			    MTK_NOR_DMA_ALIGN_MASK)) {
+			return mtk_nor_read_bounce(sp, op->addr.val,
+						   op->data.nbytes,
+						   op->data.buf.in);
+		} else {
+			return mtk_nor_read_dma(sp, op->addr.val,
+						op->data.nbytes,
+						op->data.buf.in);
+		}
+	}
+
+	return -ENOTSUPP;
+}
+
+static int mtk_nor_setup(struct spi_device *spi)
+{
+	struct mtk_nor *sp = spi_controller_get_devdata(spi->master);
+
+	if (spi->max_speed_hz && (spi->max_speed_hz < sp->spi_freq)) {
+		dev_err(&spi->dev, "spi clock should be %u Hz.\n",
+			sp->spi_freq);
+		return -EINVAL;
+	}
+	spi->max_speed_hz = sp->spi_freq;
+
+	return 0;
+}
+
+static int mtk_nor_transfer_one_message(struct spi_controller *master,
+					struct spi_message *m)
+{
+	struct mtk_nor *sp = spi_controller_get_devdata(master);
+	struct spi_transfer *t = NULL;
+	unsigned long trx_len = 0;
+	int stat = 0;
+	int reg_offset = MTK_NOR_REG_PRGDATA_MAX;
+	void __iomem *reg;
+	const u8 *txbuf;
+	u8 *rxbuf;
+	int i;
+
+	list_for_each_entry(t, &m->transfers, transfer_list) {
+		txbuf = t->tx_buf;
+		for (i = 0; i < t->len; i++, reg_offset--) {
+			reg = sp->base + MTK_NOR_REG_PRGDATA(reg_offset);
+			if (txbuf)
+				writeb(txbuf[i], reg);
+			else
+				writeb(0, reg);
+		}
+		trx_len += t->len;
+	}
+
+	writel(trx_len * BITS_PER_BYTE, sp->base + MTK_NOR_REG_PRG_CNT);
+
+	stat = mtk_nor_cmd_exec(sp, MTK_NOR_CMD_PROGRAM,
+				trx_len * BITS_PER_BYTE);
+	if (stat < 0)
+		goto msg_done;
+
+	reg_offset = trx_len - 1;
+	list_for_each_entry(t, &m->transfers, transfer_list) {
+		rxbuf = t->rx_buf;
+		for (i = 0; i < t->len; i++, reg_offset--) {
+			reg = sp->base + MTK_NOR_REG_SHIFT(reg_offset);
+			if (rxbuf)
+				rxbuf[i] = readb(reg);
+		}
+	}
+
+	m->actual_length = trx_len;
+msg_done:
+	m->status = stat;
+	spi_finalize_current_message(master);
+
+	return 0;
+}
+
+static void mtk_nor_disable_clk(struct mtk_nor *sp)
+{
+	clk_disable_unprepare(sp->spi_clk);
+	clk_disable_unprepare(sp->ctlr_clk);
+}
+
+static int mtk_nor_enable_clk(struct mtk_nor *sp)
+{
+	int ret;
+
+	ret = clk_prepare_enable(sp->spi_clk);
+	if (ret)
+		return ret;
+
+	ret = clk_prepare_enable(sp->ctlr_clk);
+	if (ret) {
+		clk_disable_unprepare(sp->spi_clk);
+		return ret;
+	}
+
+	return 0;
+}
+
+static int mtk_nor_init(struct mtk_nor *sp)
+{
+	int ret;
+
+	ret = mtk_nor_enable_clk(sp);
+	if (ret)
+		return ret;
+
+	sp->spi_freq = clk_get_rate(sp->spi_clk);
+
+	writel(MTK_NOR_ENABLE_SF_CMD, sp->base + MTK_NOR_REG_WP);
+	mtk_nor_rmw(sp, MTK_NOR_REG_CFG2, MTK_NOR_WR_CUSTOM_OP_EN, 0);
+	mtk_nor_rmw(sp, MTK_NOR_REG_CFG3,
+		    MTK_NOR_DISABLE_WREN | MTK_NOR_DISABLE_SR_POLL, 0);
+
+	return ret;
+}
+
+static irqreturn_t mtk_nor_irq_handler(int irq, void *data)
+{
+	struct mtk_nor *sp = data;
+	u32 irq_status, irq_enabled;
+
+	irq_status = readl(sp->base + MTK_NOR_REG_IRQ_STAT);
+	irq_enabled = readl(sp->base + MTK_NOR_REG_IRQ_EN);
+	// write status back to clear interrupt
+	writel(irq_status, sp->base + MTK_NOR_REG_IRQ_STAT);
+
+	if (!(irq_status & irq_enabled))
+		return IRQ_NONE;
+
+	if (irq_status & MTK_NOR_IRQ_DMA) {
+		complete(&sp->op_done);
+		writel(0, sp->base + MTK_NOR_REG_IRQ_EN);
+	}
+
+	return IRQ_HANDLED;
+}
+
+static size_t mtk_max_msg_size(struct spi_device *spi)
+{
+	return MTK_NOR_PRG_MAX_SIZE;
+}
+
+static const struct spi_controller_mem_ops mtk_nor_mem_ops = {
+	.adjust_op_size = mtk_nor_adjust_op_size,
+	.supports_op = mtk_nor_supports_op,
+	.exec_op = mtk_nor_exec_op
+};
+
+static const struct of_device_id mtk_nor_match[] = {
+	{ .compatible = "mediatek,mt8173-nor" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, mtk_nor_match);
+
+static int mtk_nor_probe(struct platform_device *pdev)
+{
+	struct spi_controller *ctlr;
+	struct mtk_nor *sp;
+	void __iomem *base;
+	u8 *buffer;
+	struct clk *spi_clk, *ctlr_clk;
+	int ret, irq;
+
+	base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(base))
+		return PTR_ERR(base);
+
+	spi_clk = devm_clk_get(&pdev->dev, "spi");
+	if (IS_ERR(spi_clk))
+		return PTR_ERR(spi_clk);
+
+	ctlr_clk = devm_clk_get(&pdev->dev, "sf");
+	if (IS_ERR(ctlr_clk))
+		return PTR_ERR(ctlr_clk);
+
+	buffer = devm_kmalloc(&pdev->dev,
+			      MTK_NOR_BOUNCE_BUF_SIZE + MTK_NOR_DMA_ALIGN,
+			      GFP_KERNEL);
+	if (!buffer)
+		return -ENOMEM;
+
+	if ((ulong)buffer & MTK_NOR_DMA_ALIGN_MASK)
+		buffer = (u8 *)(((ulong)buffer + MTK_NOR_DMA_ALIGN) &
+				~MTK_NOR_DMA_ALIGN_MASK);
+
+	ctlr = spi_alloc_master(&pdev->dev, sizeof(*sp));
+	if (!ctlr) {
+		dev_err(&pdev->dev, "failed to allocate spi controller\n");
+		return -ENOMEM;
+	}
+
+	ctlr->bits_per_word_mask = SPI_BPW_MASK(8);
+	ctlr->dev.of_node = pdev->dev.of_node;
+	ctlr->max_message_size = mtk_max_msg_size;
+	ctlr->mem_ops = &mtk_nor_mem_ops;
+	ctlr->mode_bits = SPI_RX_DUAL | SPI_RX_QUAD | SPI_TX_DUAL | SPI_TX_QUAD;
+	ctlr->num_chipselect = 1;
+	ctlr->setup = mtk_nor_setup;
+	ctlr->transfer_one_message = mtk_nor_transfer_one_message;
+
+	dev_set_drvdata(&pdev->dev, ctlr);
+
+	sp = spi_controller_get_devdata(ctlr);
+	sp->base = base;
+	sp->buffer = buffer;
+	sp->has_irq = false;
+	sp->wbuf_en = false;
+	sp->ctlr = ctlr;
+	sp->dev = &pdev->dev;
+	sp->spi_clk = spi_clk;
+	sp->ctlr_clk = ctlr_clk;
+
+	irq = platform_get_irq_optional(pdev, 0);
+	if (irq < 0) {
+		dev_warn(sp->dev, "IRQ not available.");
+	} else {
+		writel(MTK_NOR_IRQ_MASK, base + MTK_NOR_REG_IRQ_STAT);
+		writel(0, base + MTK_NOR_REG_IRQ_EN);
+		ret = devm_request_irq(sp->dev, irq, mtk_nor_irq_handler, 0,
+				       pdev->name, sp);
+		if (ret < 0) {
+			dev_warn(sp->dev, "failed to request IRQ.");
+		} else {
+			init_completion(&sp->op_done);
+			sp->has_irq = true;
+		}
+	}
+
+	ret = mtk_nor_init(sp);
+	if (ret < 0) {
+		kfree(ctlr);
+		return ret;
+	}
+
+	dev_info(&pdev->dev, "spi frequency: %d Hz\n", sp->spi_freq);
+
+	return devm_spi_register_controller(&pdev->dev, ctlr);
+}
+
+static int mtk_nor_remove(struct platform_device *pdev)
+{
+	struct spi_controller *ctlr;
+	struct mtk_nor *sp;
+
+	ctlr = dev_get_drvdata(&pdev->dev);
+	sp = spi_controller_get_devdata(ctlr);
+
+	mtk_nor_disable_clk(sp);
+
+	return 0;
+}
+
+static struct platform_driver mtk_nor_driver = {
+	.driver = {
+		.name = DRIVER_NAME,
+		.of_match_table = mtk_nor_match,
+	},
+	.probe = mtk_nor_probe,
+	.remove = mtk_nor_remove,
+};
+
+module_platform_driver(mtk_nor_driver);
+
+MODULE_DESCRIPTION("Mediatek SPI NOR controller driver");
+MODULE_AUTHOR("Chuanhong Guo <gch981213@gmail.com>");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:" DRIVER_NAME);
diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 6c223f7d1ddc..f6f6b2a0c81c 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -1951,13 +1951,8 @@ static int of_spi_parse_dt(struct spi_controller *ctlr, struct spi_device *spi,
 		spi->mode |= SPI_CS_HIGH;
 
 	/* Device speed */
-	rc = of_property_read_u32(nc, "spi-max-frequency", &value);
-	if (rc) {
-		dev_err(&ctlr->dev,
-			"%pOF has no valid 'spi-max-frequency' property (%d)\n", nc, rc);
-		return rc;
-	}
-	spi->max_speed_hz = value;
+	if (!of_property_read_u32(nc, "spi-max-frequency", &value))
+		spi->max_speed_hz = value;
 
 	return 0;
 }