Message-Id: <1431001910-4004-1-git-send-email-bert@biot.com>
Date:	Thu,  7 May 2015 14:31:50 +0200
From:	Bert Vermeulen <bert@...t.com>
To:	dwmw2@...radead.org, computersforpeace@...il.com,
	linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org
Cc:	Bert Vermeulen <bert@...t.com>
Subject: [PATCH v2] nand: Add NAND driver for Mikrotik RB4xx series boards

The NAND chip containing the root filesystem is behind an SPI-connected
CPLD. This driver uses the spi-rb4xx driver to communicate with the CPLD.

The CPLD also acts as a GPIO expander: the ALE/CLE/NCE pins are set via
CPLD commands. Some LEDs on the board are also accessed this way.

Signed-off-by: Bert Vermeulen <bert@...t.com>
---
Changes in v2:
- Fix Kconfig dependencies and description
- Move NAND partitions into platform data
- Use gpiod API with lookup table, and devm_ as needed
- Code cleanup

 arch/mips/include/asm/mach-ath79/rb4xx.h |  44 +++
 drivers/mtd/nand/Kconfig                 |   7 +
 drivers/mtd/nand/Makefile                |   1 +
 drivers/mtd/nand/rb4xx_nand.c            | 482 +++++++++++++++++++++++++++++++
 4 files changed, 534 insertions(+)
 create mode 100644 arch/mips/include/asm/mach-ath79/rb4xx.h
 create mode 100644 drivers/mtd/nand/rb4xx_nand.c

diff --git a/arch/mips/include/asm/mach-ath79/rb4xx.h b/arch/mips/include/asm/mach-ath79/rb4xx.h
new file mode 100644
index 0000000..667ea748
--- /dev/null
+++ b/arch/mips/include/asm/mach-ath79/rb4xx.h
@@ -0,0 +1,44 @@
+/*
+ * SPI driver definitions for the CPLD chip on the Mikrotik RB4xx boards
+ *
+ * Copyright (C) 2010 Gabor Juhos <juhosg@...nwrt.org>
+ *
+ * This file was based on the patches for Linux 2.6.27.39 published by
+ * MikroTik for their RouterBoard 4xx series devices.
+ *
+ * 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/spi/flash.h>
+
+#define RB4XX_GPIO_CPLD_BASE	32
+
+#define CPLD_GPIO_LED1		0
+#define CPLD_GPIO_LED2		2
+#define CPLD_GPIO_LED3		1
+#define CPLD_GPIO_LED4		3
+#define CPLD_GPIO_FAN		4
+#define CPLD_GPIO_ALE		5
+#define CPLD_GPIO_CLE		6
+#define CPLD_GPIO_NCE		7
+#define CPLD_GPIO_LED5		8
+
+#define CPLD_NUM_GPIOS		9
+
+#define CPLD_CFG_LED1		BIT(CPLD_GPIO_LED1)
+#define CPLD_CFG_LED2		BIT(CPLD_GPIO_LED2)
+#define CPLD_CFG_LED3		BIT(CPLD_GPIO_LED3)
+#define CPLD_CFG_LED4		BIT(CPLD_GPIO_LED4)
+#define CPLD_CFG_FAN		BIT(CPLD_GPIO_FAN)
+#define CPLD_CFG_ALE		BIT(CPLD_GPIO_ALE)
+#define CPLD_CFG_CLE		BIT(CPLD_GPIO_CLE)
+#define CPLD_CFG_NCE		BIT(CPLD_GPIO_NCE)
+#define CPLD_CFG_LED5		BIT(CPLD_GPIO_LED5)
+
+struct rb4xx_cpld_platform_data {
+	unsigned gpio_base;
+	struct flash_platform_data flash_data;
+};
+
diff --git a/drivers/mtd/nand/Kconfig b/drivers/mtd/nand/Kconfig
index 5897d8d..873639f 100644
--- a/drivers/mtd/nand/Kconfig
+++ b/drivers/mtd/nand/Kconfig
@@ -530,4 +530,11 @@ config MTD_NAND_HISI504
 	help
 	  Enables support for NAND controller on Hisilicon SoC Hip04.
 
+config MTD_NAND_RB4XX
+	tristate "NAND flash driver for Mikrotik RB4xx series boards"
+	depends on MTD_NAND && SPI_RB4XX
+	help
+	  Enables support for the NAND flash chip on Mikrotik Routerboard
+	  RB4xx series.
+
 endif # MTD_NAND
diff --git a/drivers/mtd/nand/Makefile b/drivers/mtd/nand/Makefile
index 582bbd05..56dbd08 100644
--- a/drivers/mtd/nand/Makefile
+++ b/drivers/mtd/nand/Makefile
@@ -52,5 +52,6 @@ obj-$(CONFIG_MTD_NAND_XWAY)		+= xway_nand.o
 obj-$(CONFIG_MTD_NAND_BCM47XXNFLASH)	+= bcm47xxnflash/
 obj-$(CONFIG_MTD_NAND_SUNXI)		+= sunxi_nand.o
 obj-$(CONFIG_MTD_NAND_HISI504)	        += hisi504_nand.o
+obj-$(CONFIG_MTD_NAND_RB4XX)	        += rb4xx_nand.o
 
 nand-objs := nand_base.o nand_bbt.o nand_timings.o
diff --git a/drivers/mtd/nand/rb4xx_nand.c b/drivers/mtd/nand/rb4xx_nand.c
new file mode 100644
index 0000000..d61ee2b
--- /dev/null
+++ b/drivers/mtd/nand/rb4xx_nand.c
@@ -0,0 +1,482 @@
+/*
+ * NAND flash driver for the MikroTik RouterBoard 4xx series
+ *
+ * Copyright (C) 2008-2011 Gabor Juhos <juhosg@...nwrt.org>
+ * Copyright (C) 2008 Imre Kaloz <kaloz@...nwrt.org>
+ * Copyright (C) 2015 Bert Vermeulen <bert@...t.com>
+ *
+ * This file was based on the driver for Linux 2.6.22 published by
+ * MikroTik for their RouterBoard 4xx series devices.
+ *
+ * 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/mtd/nand.h>
+#include <linux/spi/spi.h>
+#include <linux/platform_device.h>
+#include <linux/gpio/driver.h>
+#include <linux/gpio/consumer.h>
+
+#include <asm/mach-ath79/rb4xx.h>
+
+#define CPLD_CMD_WRITE_NAND	0x08
+#define CPLD_CMD_WRITE_CFG	0x09
+#define CPLD_CMD_READ_NAND	0x0a
+#define CPLD_CMD_READ_FAST	0x0b
+#define CPLD_CMD_LED5_ON	0x0c
+#define CPLD_CMD_LED5_OFF	0x0d
+
+struct rb4xx_nand_info {
+	struct nand_chip chip;
+	struct mtd_info mtd;
+	struct spi_device *spi_dev;
+	struct gpio_desc *gpio_rdy;
+	struct gpio_desc *gpio_ale;
+	struct gpio_desc *gpio_cle;
+	struct gpio_desc *gpio_nce;
+};
+
+struct rb4xx_cpld {
+	struct spi_device *spi;
+	struct mutex lock;
+	struct gpio_chip chip;
+	unsigned int config;
+};
+
+/*
+ * We need to use the OLD Yaffs-1 OOB layout, otherwise the RB bootloader
+ * will not be able to find the kernel that we load.
+ */
+static struct nand_ecclayout rb4xx_nand_ecclayout = {
+	.eccbytes = 6,
+	.eccpos = { 8, 9, 10, 13, 14, 15 },
+	.oobavail = 9,
+	.oobfree = { { 0, 4 }, { 6, 2 }, { 11, 2 }, { 4, 1 } }
+};
+
+static inline struct rb4xx_cpld *gpio_to_cpld(struct gpio_chip *chip)
+{
+	return container_of(chip, struct rb4xx_cpld, chip);
+}
+
+static int rb4xx_cpld_write_cmd(struct rb4xx_cpld *cpld, unsigned char cmd)
+{
+	struct spi_transfer t;
+	struct spi_message m;
+
+	spi_message_init(&m);
+
+	memset(&t, 0, sizeof(t));
+	t.tx_buf = &cmd;
+	t.len = sizeof(cmd);
+	spi_message_add_tail(&t, &m);
+	return spi_sync(cpld->spi, &m);
+}
+
+static int rb4xx_cpld_write_cfg(struct rb4xx_cpld *cpld, unsigned char config)
+{
+	struct spi_transfer t;
+	struct spi_message m;
+	unsigned char cmd[2] = {
+		CPLD_CMD_WRITE_CFG, config
+	};
+
+	spi_message_init(&m);
+
+	memset(&t, 0, sizeof(t));
+	t.tx_buf = cmd;
+	t.len = sizeof(cmd);
+	spi_message_add_tail(&t, &m);
+	return spi_sync(cpld->spi, &m);
+}
+
+static int rb4xx_cpld_change_cfg(struct rb4xx_cpld *cpld, u32 mask, u32 value)
+{
+	unsigned int config;
+	int ret;
+
+	config = cpld->config & ~mask;
+	config |= value;
+
+	if (mask & 0xff) {
+		ret = rb4xx_cpld_write_cfg(cpld, config);
+		if (ret)
+			return ret;
+	}
+
+	if (mask & CPLD_CFG_LED5) {
+		if (value & CPLD_CFG_LED5)
+			ret = rb4xx_cpld_write_cmd(cpld, CPLD_CMD_LED5_ON);
+		else
+			ret = rb4xx_cpld_write_cmd(cpld, CPLD_CMD_LED5_OFF);
+		if (ret)
+			return ret;
+	}
+
+	cpld->config = config;
+
+	return 0;
+}
+
+static int rb4xx_cpld_gpio_get(struct gpio_chip *chip, unsigned offset)
+{
+	struct rb4xx_cpld *cpld = gpio_to_cpld(chip);
+	int value;
+
+	mutex_lock(&cpld->lock);
+	value = (cpld->config >> offset) & 1;
+	mutex_unlock(&cpld->lock);
+
+	return value;
+}
+
+static void rb4xx_cpld_gpio_set(struct gpio_chip *chip,
+				unsigned offset, int value)
+{
+	struct rb4xx_cpld *cpld = gpio_to_cpld(chip);
+
+	mutex_lock(&cpld->lock);
+	rb4xx_cpld_change_cfg(cpld, (1 << offset), !!value << offset);
+	mutex_unlock(&cpld->lock);
+}
+
+static int rb4xx_cpld_gpio_direction_input(struct gpio_chip *chip,
+					   unsigned offset)
+{
+	return -EOPNOTSUPP;
+}
+
+static int rb4xx_cpld_gpio_direction_output(struct gpio_chip *chip,
+					    unsigned offset, int value)
+{
+	struct rb4xx_cpld *cpld = gpio_to_cpld(chip);
+	int ret;
+
+	mutex_lock(&cpld->lock);
+	ret = rb4xx_cpld_change_cfg(cpld, (1 << offset), !!value << offset);
+	mutex_unlock(&cpld->lock);
+
+	return ret;
+}
+
+static int rb4xx_cpld_read(struct spi_device *spi, unsigned char *rx_buf,
+			   unsigned len)
+{
+	struct spi_message m;
+	static const unsigned char cmd[2] = {
+		CPLD_CMD_READ_NAND, 0
+	};
+	struct spi_transfer t[2] = {
+		{
+			.tx_buf = &cmd,
+			.len = sizeof(cmd),
+		}, {
+			.rx_buf = rx_buf,
+			.len = len,
+		},
+	};
+
+	spi_message_init(&m);
+	spi_message_add_tail(&t[0], &m);
+	spi_message_add_tail(&t[1], &m);
+	return spi_sync(spi, &m);
+}
+
+static int rb4xx_cpld_write(struct spi_device *spi, const u8 *buf, int len)
+{
+	struct spi_message m;
+	static const unsigned char cmd = CPLD_CMD_WRITE_NAND;
+	struct spi_transfer t[3] = {
+		{
+			.tx_buf = &cmd,
+			.len = sizeof(cmd),
+		}, {
+			.tx_buf = buf,
+			.len = len,
+			.tx_nbits = SPI_NBITS_DUAL,
+		}, {
+			.len = 1,
+			.tx_nbits = SPI_NBITS_DUAL,
+		},
+	};
+
+	spi_message_init(&m);
+	spi_message_add_tail(&t[0], &m);
+	spi_message_add_tail(&t[1], &m);
+	spi_message_add_tail(&t[2], &m);
+	return spi_sync(spi, &m);
+}
+
+static int rb4xx_nand_dev_ready(struct mtd_info *mtd)
+{
+	struct nand_chip *chip = mtd->priv;
+	struct rb4xx_nand_info *info = chip->priv;
+	return gpiod_get_value_cansleep(info->gpio_rdy);
+}
+
+static void rb4xx_nand_cmd_ctrl(struct mtd_info *mtd, int cmd,
+				unsigned int ctrl)
+{
+	struct nand_chip *chip = mtd->priv;
+	struct rb4xx_nand_info *info = chip->priv;
+	u8 data = cmd;
+	int ret;
+
+	if (ctrl & NAND_CTRL_CHANGE) {
+		gpiod_set_value_cansleep(info->gpio_cle,
+					(ctrl & NAND_CLE) ? 1 : 0);
+		gpiod_set_value_cansleep(info->gpio_ale,
+					(ctrl & NAND_ALE) ? 1 : 0);
+		gpiod_set_value_cansleep(info->gpio_nce,
+					(ctrl & NAND_NCE) ? 0 : 1);
+	}
+
+	if (cmd != NAND_CMD_NONE) {
+		ret = rb4xx_cpld_write(info->spi_dev, &data, 1);
+		if (ret)
+			pr_err("rb4xx_nand: write cmd failed, error %d\n", ret);
+	}
+}
+
+static unsigned char rb4xx_nand_read_byte(struct mtd_info *mtd)
+{
+	struct nand_chip *chip = mtd->priv;
+	struct rb4xx_nand_info *info = chip->priv;
+	unsigned char data;
+	int ret;
+
+	ret = rb4xx_cpld_read(info->spi_dev, &data, 1);
+	if (ret) {
+		pr_err("rb4xx_nand: read data failed, error %d\n", ret);
+		return 0xff;
+	}
+
+	return data;
+}
+
+static void rb4xx_nand_write_buf(struct mtd_info *mtd, const unsigned char *buf,
+				 int len)
+{
+	struct nand_chip *chip = mtd->priv;
+	struct rb4xx_nand_info *info = chip->priv;
+	int ret;
+
+	ret = rb4xx_cpld_write(info->spi_dev, buf, len);
+	if (ret)
+		pr_err("rb4xx_nand: write buf failed, error %d\n", ret);
+}
+
+static void rb4xx_nand_read_buf(struct mtd_info *mtd, unsigned char *buf,
+				int len)
+{
+	struct nand_chip *chip = mtd->priv;
+	struct rb4xx_nand_info *info = chip->priv;
+	int ret;
+
+	ret = rb4xx_cpld_read(info->spi_dev, buf, len);
+	if (ret)
+		pr_err("rb4xx_nand: read buf failed, error %d\n", ret);
+}
+
+static int rb4xx_cpld_gpio_init(struct rb4xx_cpld *cpld, unsigned int base)
+{
+	int ret;
+
+	cpld->chip.label = "rb4xx-cpld";
+	cpld->chip.base = base;
+	cpld->chip.ngpio = CPLD_NUM_GPIOS;
+	cpld->chip.can_sleep = 1;
+	cpld->chip.dev = &cpld->spi->dev;
+	cpld->chip.get = rb4xx_cpld_gpio_get;
+	cpld->chip.set = rb4xx_cpld_gpio_set;
+	cpld->chip.direction_input = rb4xx_cpld_gpio_direction_input;
+	cpld->chip.direction_output = rb4xx_cpld_gpio_direction_output;
+
+	ret = gpiochip_add(&cpld->chip);
+	if (ret)
+		dev_err(&cpld->spi->dev, "adding GPIO chip failed, error %d\n",
+			ret);
+
+	return ret;
+}
+
+static int rb4xx_cpld_probe(struct spi_device *spi)
+{
+	struct rb4xx_cpld *cpld;
+	struct rb4xx_cpld_platform_data *pdata;
+	int ret;
+
+	pdata = dev_get_platdata(&spi->dev);
+	if (!pdata)
+		return -ENODATA;
+
+	cpld = devm_kzalloc(&spi->dev, sizeof(*cpld), GFP_KERNEL);
+	if (!cpld)
+		return -ENOMEM;
+
+	mutex_init(&cpld->lock);
+	cpld->spi = spi_dev_get(spi);
+	dev_set_drvdata(&spi->dev, cpld);
+
+	ret = spi_setup(spi);
+	if (ret) {
+		dev_err(&spi->dev, "SPI setup failed, error %d\n", ret);
+		return ret;
+	}
+
+	return rb4xx_cpld_gpio_init(cpld, pdata->gpio_base);
+}
+
+static int rb4xx_cpld_remove(struct spi_device *spi)
+{
+	struct rb4xx_cpld *cpld;
+
+	cpld = dev_get_drvdata(&spi->dev);
+	gpiochip_remove(&cpld->chip);
+	mutex_destroy(&cpld->lock);
+
+	return 0;
+}
+
+static struct spi_driver rb4xx_cpld_driver = {
+	.probe = rb4xx_cpld_probe,
+	.remove = rb4xx_cpld_remove,
+	.driver = {
+		.name = "rb4xx-cpld",
+		.owner = THIS_MODULE,
+	},
+};
+
+static int rb4xx_nand_probe(struct platform_device *pdev)
+{
+	struct device *spi_dev;
+	struct rb4xx_nand_info	*info;
+	struct rb4xx_cpld_platform_data *pdata;
+	int ret;
+
+	/*
+	 * NAND chip is behind the CPLD on SPI bus 0 CS 1. Allow this
+	 * to silently fail the second time around.
+	 */
+	spi_register_driver(&rb4xx_cpld_driver);
+
+	/*
+	 * Getting a handle on the SPI device above will fail the first time,
+	 * but should succeed whenever that driver gets probed.
+	 */
+	spi_dev = bus_find_device_by_name(&spi_bus_type, NULL, "spi0.1");
+	if (!spi_dev)
+		return -EPROBE_DEFER;
+
+	pdata = dev_get_platdata(spi_dev);
+	if (!pdata)
+		return -ENODATA;
+
+	info = devm_kzalloc(&pdev->dev, sizeof(*info), GFP_KERNEL);
+	if (!info)
+		return -ENOMEM;
+
+	info->gpio_ale = devm_gpiod_get(&pdev->dev, "NAND ALE", GPIOD_OUT_LOW);
+	if (IS_ERR(info->gpio_ale)) {
+		dev_err(&pdev->dev, "unable to request gpio NAND ALE: %ld\n",
+			PTR_ERR(info->gpio_ale));
+		return -ENOENT;
+	}
+
+	info->gpio_cle = devm_gpiod_get(&pdev->dev, "NAND CLE", GPIOD_OUT_LOW);
+	if (IS_ERR(info->gpio_cle)) {
+		dev_err(&pdev->dev, "unable to request gpio NAND CLE: %ld\n",
+			PTR_ERR(info->gpio_cle));
+		return -ENOENT;
+	}
+
+	info->gpio_nce = devm_gpiod_get(&pdev->dev, "NAND NCE", GPIOD_OUT_LOW);
+	if (IS_ERR(info->gpio_nce)) {
+		dev_err(&pdev->dev, "unable to request gpio NAND NCE: %ld\n",
+			PTR_ERR(info->gpio_nce));
+		return -ENOENT;
+	}
+
+	/* Platform GPIO, has no device to manage it. */
+	info->gpio_rdy = gpiod_get(NULL, "NAND RDY", GPIOD_IN);
+	if (IS_ERR(info->gpio_rdy)) {
+		dev_err(&pdev->dev, "unable to request gpio RDY: %ld\n",
+			PTR_ERR(info->gpio_rdy));
+		return -ENOENT;
+	}
+
+	info->spi_dev = container_of(spi_dev, struct spi_device, dev);
+
+	info->chip.priv	= info;
+	info->mtd.priv	= &info->chip;
+	info->mtd.owner	= THIS_MODULE;
+
+	info->chip.cmd_ctrl	= rb4xx_nand_cmd_ctrl;
+	info->chip.dev_ready	= rb4xx_nand_dev_ready;
+	info->chip.read_byte	= rb4xx_nand_read_byte;
+	info->chip.write_buf	= rb4xx_nand_write_buf;
+	info->chip.read_buf	= rb4xx_nand_read_buf;
+
+	info->chip.chip_delay	= 25;
+	info->chip.ecc.mode	= NAND_ECC_SOFT;
+
+	platform_set_drvdata(pdev, info);
+
+	ret = nand_scan_ident(&info->mtd, 1, NULL);
+	if (ret) {
+		ret = -ENXIO;
+		goto err_gpio;
+	}
+
+	if (info->mtd.writesize == 512)
+		info->chip.ecc.layout = &rb4xx_nand_ecclayout;
+
+	ret = nand_scan_tail(&info->mtd);
+	if (ret) {
+		ret = -ENXIO;
+		goto err_gpio;
+	}
+
+	ret = mtd_device_register(&info->mtd, pdata->flash_data.parts,
+				  pdata->flash_data.nr_parts);
+	if (ret)
+		goto err_release_nand;
+
+	return 0;
+
+err_release_nand:
+	nand_release(&info->mtd);
+err_gpio:
+	gpiod_put(info->gpio_rdy);
+
+	return ret;
+}
+
+static int rb4xx_nand_remove(struct platform_device *pdev)
+{
+	struct rb4xx_nand_info *info = platform_get_drvdata(pdev);
+
+	nand_release(&info->mtd);
+	gpiod_put(info->gpio_rdy);
+	spi_unregister_driver(&rb4xx_cpld_driver);
+
+	return 0;
+}
+
+static struct platform_driver rb4xx_nand_driver = {
+	.probe = rb4xx_nand_probe,
+	.remove = rb4xx_nand_remove,
+	.driver = {
+		.name = "rb4xx-nand",
+	},
+};
+
+module_platform_driver(rb4xx_nand_driver);
+
+MODULE_DESCRIPTION("NAND flash driver for RouterBoard 4xx series");
+MODULE_AUTHOR("Gabor Juhos <juhosg@...nwrt.org>");
+MODULE_AUTHOR("Imre Kaloz <kaloz@...nwrt.org>");
+MODULE_AUTHOR("Bert Vermeulen <bert@...t.com>");
+MODULE_LICENSE("GPL v2");
-- 
1.9.1

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