From 683af4ebb91a1600df1946ac4769d916b8a1be65 Mon Sep 17 00:00:00 2001
From: John Crispin <blogic@openwrt.org>
Date: Sun, 27 Jul 2014 11:15:12 +0100
Subject: [PATCH 42/53] SPI: ralink: add Ralink SoC spi driver

Add the driver needed to make SPI work on Ralink SoC.

Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
Acked-by: John Crispin <blogic@openwrt.org>
---
 drivers/spi/Kconfig      |    6 +
 drivers/spi/Makefile     |    1 +
 drivers/spi/spi-rt2880.c |  530 ++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 537 insertions(+)
 create mode 100644 drivers/spi/spi-rt2880.c

--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -563,6 +563,12 @@ config SPI_QUP
 	  This driver can also be built as a module.  If so, the module
 	  will be called spi_qup.
 
+config SPI_RT2880
+	tristate "Ralink RT288x SPI Controller"
+	depends on RALINK
+	help
+	  This selects a driver for the Ralink RT288x/RT305x SPI Controller.
+
 config SPI_S3C24XX
 	tristate "Samsung S3C24XX series SPI"
 	depends on ARCH_S3C24XX
--- a/drivers/spi/Makefile
+++ b/drivers/spi/Makefile
@@ -81,6 +81,7 @@ obj-$(CONFIG_SPI_QUP)			+= spi-qup.o
 obj-$(CONFIG_SPI_ROCKCHIP)		+= spi-rockchip.o
 obj-$(CONFIG_SPI_RB4XX)			+= spi-rb4xx.o
 obj-$(CONFIG_SPI_RSPI)			+= spi-rspi.o
+obj-$(CONFIG_SPI_RT2880)		+= spi-rt2880.o
 obj-$(CONFIG_SPI_S3C24XX)		+= spi-s3c24xx-hw.o
 spi-s3c24xx-hw-y			:= spi-s3c24xx.o
 spi-s3c24xx-hw-$(CONFIG_SPI_S3C24XX_FIQ) += spi-s3c24xx-fiq.o
--- /dev/null
+++ b/drivers/spi/spi-rt2880.c
@@ -0,0 +1,530 @@
+/*
+ * spi-rt2880.c -- Ralink RT288x/RT305x SPI controller driver
+ *
+ * Copyright (C) 2011 Sergiy <piratfm@gmail.com>
+ * Copyright (C) 2011-2013 Gabor Juhos <juhosg@openwrt.org>
+ *
+ * Some parts are based on spi-orion.c:
+ *   Author: Shadi Ammouri <shadi@marvell.com>
+ *   Copyright (C) 2007-2008 Marvell Ltd.
+ *
+ * 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
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/reset.h>
+#include <linux/spi/spi.h>
+#include <linux/platform_device.h>
+#include <linux/gpio.h>
+
+#define DRIVER_NAME			"spi-rt2880"
+
+#define RAMIPS_SPI_STAT			0x00
+#define RAMIPS_SPI_CFG			0x10
+#define RAMIPS_SPI_CTL			0x14
+#define RAMIPS_SPI_DATA			0x20
+#define RAMIPS_SPI_ADDR			0x24
+#define RAMIPS_SPI_BS			0x28
+#define RAMIPS_SPI_USER			0x2C
+#define RAMIPS_SPI_TXFIFO		0x30
+#define RAMIPS_SPI_RXFIFO		0x34
+#define RAMIPS_SPI_FIFO_STAT		0x38
+#define RAMIPS_SPI_MODE			0x3C
+#define RAMIPS_SPI_DEV_OFFSET		0x40
+#define RAMIPS_SPI_DMA			0x80
+#define RAMIPS_SPI_DMASTAT		0x84
+#define RAMIPS_SPI_ARBITER		0xF0
+
+/* SPISTAT register bit field */
+#define SPISTAT_BUSY			BIT(0)
+
+/* SPICFG register bit field */
+#define SPICFG_ADDRMODE			BIT(12)
+#define SPICFG_RXENVDIS			BIT(11)
+#define SPICFG_RXCAP			BIT(10)
+#define SPICFG_SPIENMODE		BIT(9)
+#define SPICFG_MSBFIRST			BIT(8)
+#define SPICFG_SPICLKPOL		BIT(6)
+#define SPICFG_RXCLKEDGE_FALLING	BIT(5)
+#define SPICFG_TXCLKEDGE_FALLING	BIT(4)
+#define SPICFG_HIZSPI			BIT(3)
+#define SPICFG_SPICLK_PRESCALE_MASK	0x7
+#define SPICFG_SPICLK_DIV2		0
+#define SPICFG_SPICLK_DIV4		1
+#define SPICFG_SPICLK_DIV8		2
+#define SPICFG_SPICLK_DIV16		3
+#define SPICFG_SPICLK_DIV32		4
+#define SPICFG_SPICLK_DIV64		5
+#define SPICFG_SPICLK_DIV128		6
+#define SPICFG_SPICLK_DISABLE		7
+
+/* SPICTL register bit field */
+#define SPICTL_START			BIT(4)
+#define SPICTL_HIZSDO			BIT(3)
+#define SPICTL_STARTWR			BIT(2)
+#define SPICTL_STARTRD			BIT(1)
+#define SPICTL_SPIENA			BIT(0)
+
+/* SPIUSER register bit field */
+#define SPIUSER_USERMODE		BIT(21)
+#define SPIUSER_INSTR_PHASE		BIT(20)
+#define SPIUSER_ADDR_PHASE_MASK		0x7
+#define SPIUSER_ADDR_PHASE_OFFSET	17
+#define SPIUSER_MODE_PHASE		BIT(16)
+#define SPIUSER_DUMMY_PHASE_MASK	0x3
+#define SPIUSER_DUMMY_PHASE_OFFSET	14
+#define SPIUSER_DATA_PHASE_MASK		0x3
+#define SPIUSER_DATA_PHASE_OFFSET	12
+#define SPIUSER_DATA_READ		(BIT(0) << SPIUSER_DATA_PHASE_OFFSET)
+#define SPIUSER_DATA_WRITE		(BIT(1) << SPIUSER_DATA_PHASE_OFFSET)
+#define SPIUSER_ADDR_TYPE_OFFSET	9
+#define SPIUSER_MODE_TYPE_OFFSET	6
+#define SPIUSER_DUMMY_TYPE_OFFSET	3
+#define SPIUSER_DATA_TYPE_OFFSET	0
+#define SPIUSER_TRANSFER_MASK		0x7
+#define SPIUSER_TRANSFER_SINGLE		BIT(0)
+#define SPIUSER_TRANSFER_DUAL		BIT(1)
+#define SPIUSER_TRANSFER_QUAD		BIT(2)
+
+#define SPIUSER_TRANSFER_TYPE(type) ( \
+	(type << SPIUSER_ADDR_TYPE_OFFSET) | \
+	(type << SPIUSER_MODE_TYPE_OFFSET) | \
+	(type << SPIUSER_DUMMY_TYPE_OFFSET) | \
+	(type << SPIUSER_DATA_TYPE_OFFSET) \
+)
+
+/* SPIFIFOSTAT register bit field */
+#define SPIFIFOSTAT_TXEMPTY		BIT(19)
+#define SPIFIFOSTAT_RXEMPTY		BIT(18)
+#define SPIFIFOSTAT_TXFULL		BIT(17)
+#define SPIFIFOSTAT_RXFULL		BIT(16)
+#define SPIFIFOSTAT_FIFO_MASK		0xff
+#define SPIFIFOSTAT_TX_OFFSET		8
+#define SPIFIFOSTAT_RX_OFFSET		0
+
+#define SPI_FIFO_DEPTH			16
+
+/* SPIMODE register bit field */
+#define SPIMODE_MODE_OFFSET		24
+#define SPIMODE_DUMMY_OFFSET		0
+
+/* SPIARB register bit field */
+#define SPICTL_ARB_EN			BIT(31)
+#define SPICTL_CSCTL1			BIT(16)
+#define SPI1_POR			BIT(1)
+#define SPI0_POR			BIT(0)
+
+#define RT2880_SPI_MODE_BITS	(SPI_CPOL | SPI_CPHA | SPI_LSB_FIRST | \
+		SPI_CS_HIGH)
+
+static atomic_t hw_reset_count = ATOMIC_INIT(0);
+
+struct rt2880_spi {
+	struct spi_master	*master;
+	void __iomem		*base;
+	u32			speed;
+	u16			wait_loops;
+	u16			mode;
+	struct clk		*clk;
+};
+
+static inline struct rt2880_spi *spidev_to_rt2880_spi(struct spi_device *spi)
+{
+	return spi_master_get_devdata(spi->master);
+}
+
+static inline u32 rt2880_spi_read(struct rt2880_spi *rs, u32 reg)
+{
+	return ioread32(rs->base + reg);
+}
+
+static inline void rt2880_spi_write(struct rt2880_spi *rs, u32 reg,
+		const u32 val)
+{
+	iowrite32(val, rs->base + reg);
+}
+
+static inline void rt2880_spi_setbits(struct rt2880_spi *rs, u32 reg, u32 mask)
+{
+	void __iomem *addr = rs->base + reg;
+
+	iowrite32((ioread32(addr) | mask), addr);
+}
+
+static inline void rt2880_spi_clrbits(struct rt2880_spi *rs, u32 reg, u32 mask)
+{
+	void __iomem *addr = rs->base + reg;
+
+	iowrite32((ioread32(addr) & ~mask), addr);
+}
+
+static u32 rt2880_spi_baudrate_get(struct spi_device *spi, unsigned int speed)
+{
+	struct rt2880_spi *rs = spidev_to_rt2880_spi(spi);
+	u32 rate;
+	u32 prescale;
+
+	/*
+	 * the supported rates are: 2, 4, 8, ... 128
+	 * round up as we look for equal or less speed
+	 */
+	rate = DIV_ROUND_UP(clk_get_rate(rs->clk), speed);
+	rate = roundup_pow_of_two(rate);
+
+	/* Convert the rate to SPI clock divisor value.	*/
+	prescale = ilog2(rate / 2);
+
+	/* some tolerance. double and add 100 */
+	rs->wait_loops = (8 * HZ * loops_per_jiffy) /
+		(clk_get_rate(rs->clk) / rate);
+	rs->wait_loops = (rs->wait_loops << 1) + 100;
+	rs->speed = speed;
+
+	dev_dbg(&spi->dev, "speed: %lu/%u, rate: %u, prescal: %u, loops: %hu\n",
+			clk_get_rate(rs->clk) / rate, speed, rate, prescale,
+			rs->wait_loops);
+
+	return prescale;
+}
+
+static u32 get_arbiter_offset(struct spi_master *master)
+{
+	u32 offset;
+
+	offset = RAMIPS_SPI_ARBITER;
+	if (master->bus_num == 1)
+		offset -= RAMIPS_SPI_DEV_OFFSET;
+
+	return offset;
+}
+
+static void rt2880_spi_set_cs(struct spi_device *spi, bool enable)
+{
+	struct rt2880_spi *rs = spidev_to_rt2880_spi(spi);
+
+	if (enable)
+		rt2880_spi_setbits(rs, RAMIPS_SPI_CTL, SPICTL_SPIENA);
+	else
+		rt2880_spi_clrbits(rs, RAMIPS_SPI_CTL, SPICTL_SPIENA);
+}
+
+static int rt2880_spi_wait_ready(struct rt2880_spi *rs, int len)
+{
+	int loop = rs->wait_loops * len;
+
+	while ((rt2880_spi_read(rs, RAMIPS_SPI_STAT) & SPISTAT_BUSY) && --loop)
+		cpu_relax();
+
+	if (loop)
+		return 0;
+
+	return -ETIMEDOUT;
+}
+
+static void rt2880_dump_reg(struct spi_master *master)
+{
+	struct rt2880_spi *rs = spi_master_get_devdata(master);
+
+	dev_dbg(&master->dev, "stat: %08x, cfg: %08x, ctl: %08x, " \
+			"data: %08x, arb: %08x\n",
+			rt2880_spi_read(rs, RAMIPS_SPI_STAT),
+			rt2880_spi_read(rs, RAMIPS_SPI_CFG),
+			rt2880_spi_read(rs, RAMIPS_SPI_CTL),
+			rt2880_spi_read(rs, RAMIPS_SPI_DATA),
+			rt2880_spi_read(rs, get_arbiter_offset(master)));
+}
+
+static int rt2880_spi_transfer_one(struct spi_master *master,
+		struct spi_device *spi, struct spi_transfer *xfer)
+{
+	struct rt2880_spi *rs = spi_master_get_devdata(master);
+	unsigned len;
+	const u8 *tx = xfer->tx_buf;
+	u8 *rx = xfer->rx_buf;
+	int err = 0;
+
+	/* change clock speed  */
+	if (unlikely(rs->speed != xfer->speed_hz)) {
+		u32 reg;
+		reg = rt2880_spi_read(rs, RAMIPS_SPI_CFG);
+		reg &= ~SPICFG_SPICLK_PRESCALE_MASK;
+		reg |= rt2880_spi_baudrate_get(spi, xfer->speed_hz);
+		rt2880_spi_write(rs, RAMIPS_SPI_CFG, reg);
+	}
+
+	if (tx) {
+		len = xfer->len;
+		while (len-- > 0) {
+			rt2880_spi_write(rs, RAMIPS_SPI_DATA, *tx++);
+			rt2880_spi_setbits(rs, RAMIPS_SPI_CTL, SPICTL_STARTWR);
+			err = rt2880_spi_wait_ready(rs, 1);
+			if (err) {
+				dev_err(&spi->dev, "TX failed, err=%d\n", err);
+				goto out;
+			}
+		}
+	}
+
+	if (rx) {
+		len = xfer->len;
+		while (len-- > 0) {
+			rt2880_spi_setbits(rs, RAMIPS_SPI_CTL, SPICTL_STARTRD);
+			err = rt2880_spi_wait_ready(rs, 1);
+			if (err) {
+				dev_err(&spi->dev, "RX failed, err=%d\n", err);
+				goto out;
+			}
+			*rx++ = (u8) rt2880_spi_read(rs, RAMIPS_SPI_DATA);
+		}
+	}
+
+out:
+	return err;
+}
+
+/* copy from spi.c */
+static void spi_set_cs(struct spi_device *spi, bool enable)
+{
+	if (spi->mode & SPI_CS_HIGH)
+		enable = !enable;
+
+	if (spi->cs_gpio >= 0)
+		gpio_set_value(spi->cs_gpio, !enable);
+	else if (spi->master->set_cs)
+		spi->master->set_cs(spi, !enable);
+}
+
+static int rt2880_spi_setup(struct spi_device *spi)
+{
+	struct spi_master *master = spi->master;
+	struct rt2880_spi *rs = spi_master_get_devdata(master);
+	u32 reg, old_reg, arbit_off;
+
+	if ((spi->max_speed_hz > master->max_speed_hz) ||
+			(spi->max_speed_hz < master->min_speed_hz)) {
+		dev_err(&spi->dev, "invalide requested speed %d Hz\n",
+				spi->max_speed_hz);
+		return -EINVAL;
+	}
+
+	if (!(master->bits_per_word_mask &
+				BIT(spi->bits_per_word - 1))) {
+		dev_err(&spi->dev, "invalide bits_per_word %d\n",
+				spi->bits_per_word);
+		return -EINVAL;
+	}
+
+	/* the hardware seems can't work on mode0 force it to mode3 */
+	if ((spi->mode & (SPI_CPOL | SPI_CPHA)) == SPI_MODE_0) {
+		dev_warn(&spi->dev, "force spi mode3\n");
+		spi->mode |= SPI_MODE_3;
+	}
+
+	/* chip polarity */
+	arbit_off = get_arbiter_offset(master);
+	reg = old_reg = rt2880_spi_read(rs, arbit_off);
+	if (spi->mode & SPI_CS_HIGH) {
+		switch (master->bus_num) {
+		case 1:
+			reg |= SPI1_POR;
+			break;
+		default:
+			reg |= SPI0_POR;
+			break;
+		}
+	} else {
+		switch (master->bus_num) {
+		case 1:
+			reg &= ~SPI1_POR;
+			break;
+		default:
+			reg &= ~SPI0_POR;
+			break;
+		}
+	}
+
+	/* enable spi1 */
+	if (master->bus_num == 1)
+		reg |= SPICTL_ARB_EN;
+
+	if (reg != old_reg)
+		rt2880_spi_write(rs, arbit_off, reg);
+
+	/* deselected the spi device */
+	spi_set_cs(spi, false);
+
+	rt2880_dump_reg(master);
+
+	return 0;
+}
+
+static int rt2880_spi_prepare_message(struct spi_master *master,
+		struct spi_message *msg)
+{
+	struct rt2880_spi *rs = spi_master_get_devdata(master);
+	struct spi_device *spi = msg->spi;
+	u32 reg;
+
+	if ((rs->mode == spi->mode) && (rs->speed == spi->max_speed_hz))
+		return 0;
+
+#if 0
+	/* set spido to tri-state */
+	rt2880_spi_setbits(rs, RAMIPS_SPI_CTL, SPICTL_HIZSDO);
+#endif
+
+	reg = rt2880_spi_read(rs, RAMIPS_SPI_CFG);
+
+	reg &= ~(SPICFG_MSBFIRST | SPICFG_SPICLKPOL |
+			SPICFG_RXCLKEDGE_FALLING |
+			SPICFG_TXCLKEDGE_FALLING |
+			SPICFG_SPICLK_PRESCALE_MASK);
+
+	/* MSB */
+	if (!(spi->mode & SPI_LSB_FIRST))
+		reg |= SPICFG_MSBFIRST;
+
+	/* spi mode */
+	switch (spi->mode & (SPI_CPOL | SPI_CPHA)) {
+	case SPI_MODE_0:
+		reg |= SPICFG_TXCLKEDGE_FALLING;
+		break;
+	case SPI_MODE_1:
+		reg |= SPICFG_RXCLKEDGE_FALLING;
+		break;
+	case SPI_MODE_2:
+		reg |= SPICFG_SPICLKPOL | SPICFG_RXCLKEDGE_FALLING;
+		break;
+	case SPI_MODE_3:
+		reg |= SPICFG_SPICLKPOL | SPICFG_TXCLKEDGE_FALLING;
+		break;
+	}
+	rs->mode = spi->mode;
+
+#if 0
+	/* set spiclk and spiena to tri-state */
+	reg |= SPICFG_HIZSPI;
+#endif
+
+	/* clock divide */
+	reg |= rt2880_spi_baudrate_get(spi, spi->max_speed_hz);
+
+	rt2880_spi_write(rs, RAMIPS_SPI_CFG, reg);
+
+	return 0;
+}
+
+static int rt2880_spi_probe(struct platform_device *pdev)
+{
+	struct spi_master *master;
+	struct rt2880_spi *rs;
+	void __iomem *base;
+	struct resource *r;
+	struct clk *clk;
+	int ret;
+
+	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\n");
+		return PTR_ERR(clk);
+	}
+
+	ret = clk_prepare_enable(clk);
+	if (ret)
+		goto err_clk;
+
+	master = spi_alloc_master(&pdev->dev, sizeof(*rs));
+	if (master == NULL) {
+		dev_dbg(&pdev->dev, "master allocation failed\n");
+		ret = -ENOMEM;
+		goto err_clk;
+	}
+
+	master->dev.of_node = pdev->dev.of_node;
+	master->mode_bits = RT2880_SPI_MODE_BITS;
+	master->bits_per_word_mask = SPI_BPW_MASK(8);
+	master->min_speed_hz = clk_get_rate(clk) / 128;
+	master->max_speed_hz = clk_get_rate(clk) / 2;
+	master->flags = SPI_MASTER_HALF_DUPLEX;
+	master->setup = rt2880_spi_setup;
+	master->prepare_message = rt2880_spi_prepare_message;
+	master->set_cs = rt2880_spi_set_cs;
+	master->transfer_one = rt2880_spi_transfer_one,
+
+	dev_set_drvdata(&pdev->dev, master);
+
+	rs = spi_master_get_devdata(master);
+	rs->master = master;
+	rs->base = base;
+	rs->clk = clk;
+
+	if (atomic_inc_return(&hw_reset_count) == 1)
+		device_reset(&pdev->dev);
+
+	ret = devm_spi_register_master(&pdev->dev, master);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "devm_spi_register_master error.\n");
+		goto err_master;
+	}
+
+	return ret;
+
+err_master:
+	spi_master_put(master);
+	kfree(master);
+err_clk:
+	clk_disable_unprepare(clk);
+
+	return ret;
+}
+
+static int rt2880_spi_remove(struct platform_device *pdev)
+{
+	struct spi_master *master;
+	struct rt2880_spi *rs;
+
+	master = dev_get_drvdata(&pdev->dev);
+	rs = spi_master_get_devdata(master);
+
+	clk_disable_unprepare(rs->clk);
+	atomic_dec(&hw_reset_count);
+
+	return 0;
+}
+
+MODULE_ALIAS("platform:" DRIVER_NAME);
+
+static const struct of_device_id rt2880_spi_match[] = {
+	{ .compatible = "ralink,rt2880-spi" },
+	{},
+};
+MODULE_DEVICE_TABLE(of, rt2880_spi_match);
+
+static struct platform_driver rt2880_spi_driver = {
+	.driver = {
+		.name = DRIVER_NAME,
+		.owner = THIS_MODULE,
+		.of_match_table = rt2880_spi_match,
+	},
+	.probe = rt2880_spi_probe,
+	.remove = rt2880_spi_remove,
+};
+
+module_platform_driver(rt2880_spi_driver);
+
+MODULE_DESCRIPTION("Ralink SPI driver");
+MODULE_AUTHOR("Sergiy <piratfm@gmail.com>");
+MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>");
+MODULE_LICENSE("GPL");
