spi: mt7621: Move SPI driver out of staging

This patch moves the MT7621 SPI driver, which is used on some Ralink /
MediaTek MT76xx MIPS SoC's, out of the staging directory. No changes to
the source code are done in this patch.

This driver version was tested successfully on an MT7688 based platform
with an SPI NOR on CS0 and an SPI NAND on CS1 without any issues (so
far).

This patch also documents the devicetree bindings for the MT7621 SPI
device driver.

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Rob Herring <robh@kernel.org>
Cc: Mark Brown <broonie@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: NeilBrown <neil@brown.name>
Cc: Sankalp Negi <sankalpnegi2310@gmail.com>
Cc: Chuanhong Guo <gch981213@gmail.com>
Cc: John Crispin <john@phrozen.org>
Cc: Armando Miraglia <arma2ff0@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

3 files changed, 428 insertions, 0 deletions

diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index f761655e2a36..8ce4f7df0ef2 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -426,6 +426,12 @@ config SPI_MT65XX
 	  say Y or M here.If you are not sure, say N.
 	  SPI drivers for Mediatek MT65XX and MT81XX series ARM SoCs.
 
+config SPI_MT7621
+	tristate "MediaTek MT7621 SPI Controller"
+	depends on RALINK || COMPILE_TEST
+	help
+	  This selects a driver for the MediaTek MT7621 SPI Controller.
+
 config SPI_NPCM_PSPI
 	tristate "Nuvoton NPCM PSPI Controller"
 	depends on ARCH_NPCM || COMPILE_TEST
diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
index d8fc03c9faa2..369f29a8a6af 100644
--- a/drivers/spi/Makefile
+++ b/drivers/spi/Makefile
@@ -60,6 +60,7 @@ obj-$(CONFIG_SPI_MPC512x_PSC)		+= spi-mpc512x-psc.o
 obj-$(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_MXIC)			+= spi-mxic.o
 obj-$(CONFIG_SPI_MXS)			+= spi-mxs.o
 obj-$(CONFIG_SPI_NPCM_PSPI)		+= spi-npcm-pspi.o
diff --git a/drivers/spi/spi-mt7621.c b/drivers/spi/spi-mt7621.c
new file mode 100644
index 000000000000..ae836114ee3d
--- /dev/null
+++ b/drivers/spi/spi-mt7621.c
@@ -0,0 +1,421 @@
+// SPDX-License-Identifier: GPL-2.0
+//
+// spi-mt7621.c -- MediaTek MT7621 SPI controller driver
+//
+// Copyright (C) 2011 Sergiy <piratfm@gmail.com>
+// Copyright (C) 2011-2013 Gabor Juhos <juhosg@openwrt.org>
+// Copyright (C) 2014-2015 Felix Fietkau <nbd@nbd.name>
+//
+// Some parts are based on spi-orion.c:
+//   Author: Shadi Ammouri <shadi@marvell.com>
+//   Copyright (C) 2007-2008 Marvell Ltd.
+
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/reset.h>
+#include <linux/spi/spi.h>
+
+#define DRIVER_NAME		"spi-mt7621"
+
+/* in usec */
+#define RALINK_SPI_WAIT_MAX_LOOP 2000
+
+/* SPISTAT register bit field */
+#define SPISTAT_BUSY		BIT(0)
+
+#define MT7621_SPI_TRANS	0x00
+#define SPITRANS_BUSY		BIT(16)
+
+#define MT7621_SPI_OPCODE	0x04
+#define MT7621_SPI_DATA0	0x08
+#define MT7621_SPI_DATA4	0x18
+#define SPI_CTL_TX_RX_CNT_MASK	0xff
+#define SPI_CTL_START		BIT(8)
+
+#define MT7621_SPI_MASTER	0x28
+#define MASTER_MORE_BUFMODE	BIT(2)
+#define MASTER_FULL_DUPLEX	BIT(10)
+#define MASTER_RS_CLK_SEL	GENMASK(27, 16)
+#define MASTER_RS_CLK_SEL_SHIFT	16
+#define MASTER_RS_SLAVE_SEL	GENMASK(31, 29)
+
+#define MT7621_SPI_MOREBUF	0x2c
+#define MT7621_SPI_POLAR	0x38
+#define MT7621_SPI_SPACE	0x3c
+
+#define MT7621_CPHA		BIT(5)
+#define MT7621_CPOL		BIT(4)
+#define MT7621_LSB_FIRST	BIT(3)
+
+struct mt7621_spi {
+	struct spi_controller	*master;
+	void __iomem		*base;
+	unsigned int		sys_freq;
+	unsigned int		speed;
+	struct clk		*clk;
+	int			pending_write;
+
+	struct mt7621_spi_ops	*ops;
+};
+
+static inline struct mt7621_spi *spidev_to_mt7621_spi(struct spi_device *spi)
+{
+	return spi_controller_get_devdata(spi->master);
+}
+
+static inline u32 mt7621_spi_read(struct mt7621_spi *rs, u32 reg)
+{
+	return ioread32(rs->base + reg);
+}
+
+static inline void mt7621_spi_write(struct mt7621_spi *rs, u32 reg, u32 val)
+{
+	iowrite32(val, rs->base + reg);
+}
+
+static void mt7621_spi_set_cs(struct spi_device *spi, int enable)
+{
+	struct mt7621_spi *rs = spidev_to_mt7621_spi(spi);
+	int cs = spi->chip_select;
+	u32 polar = 0;
+	u32 master;
+
+	/*
+	 * Select SPI device 7, enable "more buffer mode" and disable
+	 * full-duplex (only half-duplex really works on this chip
+	 * reliably)
+	 */
+	master = mt7621_spi_read(rs, MT7621_SPI_MASTER);
+	master |= MASTER_RS_SLAVE_SEL | MASTER_MORE_BUFMODE;
+	master &= ~MASTER_FULL_DUPLEX;
+	mt7621_spi_write(rs, MT7621_SPI_MASTER, master);
+
+	rs->pending_write = 0;
+
+	if (enable)
+		polar = BIT(cs);
+	mt7621_spi_write(rs, MT7621_SPI_POLAR, polar);
+}
+
+static int mt7621_spi_prepare(struct spi_device *spi, unsigned int speed)
+{
+	struct mt7621_spi *rs = spidev_to_mt7621_spi(spi);
+	u32 rate;
+	u32 reg;
+
+	dev_dbg(&spi->dev, "speed:%u\n", speed);
+
+	rate = DIV_ROUND_UP(rs->sys_freq, speed);
+	dev_dbg(&spi->dev, "rate-1:%u\n", rate);
+
+	if (rate > 4097)
+		return -EINVAL;
+
+	if (rate < 2)
+		rate = 2;
+
+	reg = mt7621_spi_read(rs, MT7621_SPI_MASTER);
+	reg &= ~MASTER_RS_CLK_SEL;
+	reg |= (rate - 2) << MASTER_RS_CLK_SEL_SHIFT;
+	rs->speed = speed;
+
+	reg &= ~MT7621_LSB_FIRST;
+	if (spi->mode & SPI_LSB_FIRST)
+		reg |= MT7621_LSB_FIRST;
+
+	/*
+	 * This SPI controller seems to be tested on SPI flash only and some
+	 * bits are swizzled under other SPI modes probably due to incorrect
+	 * wiring inside the silicon. Only mode 0 works correctly.
+	 */
+	reg &= ~(MT7621_CPHA | MT7621_CPOL);
+
+	mt7621_spi_write(rs, MT7621_SPI_MASTER, reg);
+
+	return 0;
+}
+
+static inline int mt7621_spi_wait_till_ready(struct mt7621_spi *rs)
+{
+	int i;
+
+	for (i = 0; i < RALINK_SPI_WAIT_MAX_LOOP; i++) {
+		u32 status;
+
+		status = mt7621_spi_read(rs, MT7621_SPI_TRANS);
+		if ((status & SPITRANS_BUSY) == 0)
+			return 0;
+		cpu_relax();
+		udelay(1);
+	}
+
+	return -ETIMEDOUT;
+}
+
+static void mt7621_spi_read_half_duplex(struct mt7621_spi *rs,
+					int rx_len, u8 *buf)
+{
+	int tx_len;
+
+	/*
+	 * Combine with any pending write, and perform one or more half-duplex
+	 * transactions reading 'len' bytes. Data to be written is already in
+	 * MT7621_SPI_DATA.
+	 */
+	tx_len = rs->pending_write;
+	rs->pending_write = 0;
+
+	while (rx_len || tx_len) {
+		int i;
+		u32 val = (min(tx_len, 4) * 8) << 24;
+		int rx = min(rx_len, 32);
+
+		if (tx_len > 4)
+			val |= (tx_len - 4) * 8;
+		val |= (rx * 8) << 12;
+		mt7621_spi_write(rs, MT7621_SPI_MOREBUF, val);
+
+		tx_len = 0;
+
+		val = mt7621_spi_read(rs, MT7621_SPI_TRANS);
+		val |= SPI_CTL_START;
+		mt7621_spi_write(rs, MT7621_SPI_TRANS, val);
+
+		mt7621_spi_wait_till_ready(rs);
+
+		for (i = 0; i < rx; i++) {
+			if ((i % 4) == 0)
+				val = mt7621_spi_read(rs, MT7621_SPI_DATA0 + i);
+			*buf++ = val & 0xff;
+			val >>= 8;
+		}
+
+		rx_len -= i;
+	}
+}
+
+static inline void mt7621_spi_flush(struct mt7621_spi *rs)
+{
+	mt7621_spi_read_half_duplex(rs, 0, NULL);
+}
+
+static void mt7621_spi_write_half_duplex(struct mt7621_spi *rs,
+					 int tx_len, const u8 *buf)
+{
+	int len = rs->pending_write;
+	int val = 0;
+
+	if (len & 3) {
+		val = mt7621_spi_read(rs, MT7621_SPI_OPCODE + (len & ~3));
+		if (len < 4) {
+			val <<= (4 - len) * 8;
+			val = swab32(val);
+		}
+	}
+
+	while (tx_len > 0) {
+		if (len >= 36) {
+			rs->pending_write = len;
+			mt7621_spi_flush(rs);
+			len = 0;
+		}
+
+		val |= *buf++ << (8 * (len & 3));
+		len++;
+		if ((len & 3) == 0) {
+			if (len == 4)
+				/* The byte-order of the opcode is weird! */
+				val = swab32(val);
+			mt7621_spi_write(rs, MT7621_SPI_OPCODE + len - 4, val);
+			val = 0;
+		}
+		tx_len -= 1;
+	}
+
+	if (len & 3) {
+		if (len < 4) {
+			val = swab32(val);
+			val >>= (4 - len) * 8;
+		}
+		mt7621_spi_write(rs, MT7621_SPI_OPCODE + (len & ~3), val);
+	}
+
+	rs->pending_write = len;
+}
+
+static int mt7621_spi_transfer_one_message(struct spi_controller *master,
+					   struct spi_message *m)
+{
+	struct mt7621_spi *rs = spi_controller_get_devdata(master);
+	struct spi_device *spi = m->spi;
+	unsigned int speed = spi->max_speed_hz;
+	struct spi_transfer *t = NULL;
+	int status = 0;
+
+	mt7621_spi_wait_till_ready(rs);
+
+	list_for_each_entry(t, &m->transfers, transfer_list)
+		if (t->speed_hz < speed)
+			speed = t->speed_hz;
+
+	if (mt7621_spi_prepare(spi, speed)) {
+		status = -EIO;
+		goto msg_done;
+	}
+
+	/* Assert CS */
+	mt7621_spi_set_cs(spi, 1);
+
+	m->actual_length = 0;
+	list_for_each_entry(t, &m->transfers, transfer_list) {
+		if ((t->rx_buf) && (t->tx_buf)) {
+			/*
+			 * This controller will shift some extra data out
+			 * of spi_opcode if (mosi_bit_cnt > 0) &&
+			 * (cmd_bit_cnt == 0). So the claimed full-duplex
+			 * support is broken since we have no way to read
+			 * the MISO value during that bit.
+			 */
+			status = -EIO;
+			goto msg_done;
+		} else if (t->rx_buf) {
+			mt7621_spi_read_half_duplex(rs, t->len, t->rx_buf);
+		} else if (t->tx_buf) {
+			mt7621_spi_write_half_duplex(rs, t->len, t->tx_buf);
+		}
+		m->actual_length += t->len;
+	}
+
+	/* Flush data and deassert CS */
+	mt7621_spi_flush(rs);
+	mt7621_spi_set_cs(spi, 0);
+
+msg_done:
+	m->status = status;
+	spi_finalize_current_message(master);
+
+	return 0;
+}
+
+static int mt7621_spi_setup(struct spi_device *spi)
+{
+	struct mt7621_spi *rs = spidev_to_mt7621_spi(spi);
+
+	if ((spi->max_speed_hz == 0) ||
+	    (spi->max_speed_hz > (rs->sys_freq / 2)))
+		spi->max_speed_hz = (rs->sys_freq / 2);
+
+	if (spi->max_speed_hz < (rs->sys_freq / 4097)) {
+		dev_err(&spi->dev, "setup: requested speed is too low %d Hz\n",
+			spi->max_speed_hz);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static const struct of_device_id mt7621_spi_match[] = {
+	{ .compatible = "ralink,mt7621-spi" },
+	{},
+};
+MODULE_DEVICE_TABLE(of, mt7621_spi_match);
+
+static int mt7621_spi_probe(struct platform_device *pdev)
+{
+	const struct of_device_id *match;
+	struct spi_controller *master;
+	struct mt7621_spi *rs;
+	void __iomem *base;
+	struct resource *r;
+	int status = 0;
+	struct clk *clk;
+	struct mt7621_spi_ops *ops;
+	int ret;
+
+	match = of_match_device(mt7621_spi_match, &pdev->dev);
+	if (!match)
+		return -EINVAL;
+	ops = (struct mt7621_spi_ops *)match->data;
+
+	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	base = devm_ioremap_resource(&pdev->dev, r);
+	if (IS_ERR(base))
+		return PTR_ERR(base);
+
+	clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(clk)) {
+		dev_err(&pdev->dev, "unable to get SYS clock, err=%d\n",
+			status);
+		return PTR_ERR(clk);
+	}
+
+	status = clk_prepare_enable(clk);
+	if (status)
+		return status;
+
+	master = spi_alloc_master(&pdev->dev, sizeof(*rs));
+	if (!master) {
+		dev_info(&pdev->dev, "master allocation failed\n");
+		return -ENOMEM;
+	}
+
+	master->mode_bits = SPI_LSB_FIRST;
+	master->flags = SPI_CONTROLLER_HALF_DUPLEX;
+	master->setup = mt7621_spi_setup;
+	master->transfer_one_message = mt7621_spi_transfer_one_message;
+	master->bits_per_word_mask = SPI_BPW_MASK(8);
+	master->dev.of_node = pdev->dev.of_node;
+	master->num_chipselect = 2;
+
+	dev_set_drvdata(&pdev->dev, master);
+
+	rs = spi_controller_get_devdata(master);
+	rs->base = base;
+	rs->clk = clk;
+	rs->master = master;
+	rs->sys_freq = clk_get_rate(rs->clk);
+	rs->ops = ops;
+	rs->pending_write = 0;
+	dev_info(&pdev->dev, "sys_freq: %u\n", rs->sys_freq);
+
+	ret = device_reset(&pdev->dev);
+	if (ret) {
+		dev_err(&pdev->dev, "SPI reset failed!\n");
+		return ret;
+	}
+
+	return devm_spi_register_controller(&pdev->dev, master);
+}
+
+static int mt7621_spi_remove(struct platform_device *pdev)
+{
+	struct spi_controller *master;
+	struct mt7621_spi *rs;
+
+	master = dev_get_drvdata(&pdev->dev);
+	rs = spi_controller_get_devdata(master);
+
+	clk_disable_unprepare(rs->clk);
+
+	return 0;
+}
+
+MODULE_ALIAS("platform:" DRIVER_NAME);
+
+static struct platform_driver mt7621_spi_driver = {
+	.driver = {
+		.name = DRIVER_NAME,
+		.of_match_table = mt7621_spi_match,
+	},
+	.probe = mt7621_spi_probe,
+	.remove = mt7621_spi_remove,
+};
+
+module_platform_driver(mt7621_spi_driver);
+
+MODULE_DESCRIPTION("MT7621 SPI driver");
+MODULE_AUTHOR("Felix Fietkau <nbd@nbd.name>");
+MODULE_LICENSE("GPL");