1 files changed, 421 insertions, 0 deletions
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");