[MTD] [NAND] GPIO NAND flash driver

The patch adds support for NAND flashes connected to GPIOs.

Signed-off-by: Russell King <[e-mail]>
Signed-off-by: Mike Rapoport <[e-mail]>
Signed-off-by: David Woodhouse <[e-mail]>

drivers/mtd/nand/Kconfig

···
 	help
 	  This enables the driver for the iPAQ h1900 flash.
 
+config MTD_NAND_GPIO
+	tristate "GPIO NAND Flash driver"
+	depends on GENERIC_GPIO
+	help
+	  This enables a GPIO based NAND flash driver.
+
 config MTD_NAND_SPIA
 	tristate "NAND Flash device on SPIA board"
 	depends on ARCH_P720T

drivers/mtd/nand/Makefile

···
 obj-$(CONFIG_MTD_NAND_CS553X)		+= cs553x_nand.o
 obj-$(CONFIG_MTD_NAND_NDFC)		+= ndfc.o
 obj-$(CONFIG_MTD_NAND_ATMEL)		+= atmel_nand.o
+obj-$(CONFIG_MTD_NAND_GPIO)		+= gpio.o
 obj-$(CONFIG_MTD_NAND_CM_X270)		+= cmx270_nand.o
 obj-$(CONFIG_MTD_NAND_BASLER_EXCITE)	+= excite_nandflash.o
 obj-$(CONFIG_MTD_NAND_PXA3xx)		+= pxa3xx_nand.o

drivers/mtd/nand/gpio.c

···
+/*
+ * drivers/mtd/nand/gpio.c
+ *
+ * Updated, and converted to generic GPIO based driver by Russell King.
+ *
+ * Written by Ben Dooks <[e-mail]>
+ *   Based on 2.4 version by Mark Whittaker
+ *
+ * © 2004 Simtec Electronics
+ *
+ * Device driver for NAND connected via GPIO
+ *
+ * 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/kernel.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/gpio.h>
+#include <linux/io.h>
+#include <linux/mtd/mtd.h>
+#include <linux/mtd/nand.h>
+#include <linux/mtd/partitions.h>
+#include <linux/mtd/nand-gpio.h>
+
+struct gpiomtd {
+	void __iomem		*io_sync;
+	struct mtd_info		mtd_info;
+	struct nand_chip	nand_chip;
+	struct gpio_nand_platdata plat;
+};
+
+#define gpio_nand_getpriv(x) container_of(x, struct gpiomtd, mtd_info)
+
+
+#ifdef CONFIG_ARM
+/* gpio_nand_dosync()
+ *
+ * Make sure the GPIO state changes occur in-order with writes to NAND
+ * memory region.
+ * Needed on PXA due to bus-reordering within the SoC itself (see section on
+ * I/O ordering in PXA manual (section 2.3, p35)
+ */
+static void gpio_nand_dosync(struct gpiomtd *gpiomtd)
+{
+	unsigned long tmp;
+
+	if (gpiomtd->io_sync) {
+		/*
+		 * Linux memory barriers don't cater for what's required here.
+		 * What's required is what's here - a read from a separate
+		 * region with a dependency on that read.
+		 */
+		tmp = readl(gpiomtd->io_sync);
+		asm volatile("mov %1, %0\n" : "=r" (tmp) : "r" (tmp));
+	}
+}
+#else
+static inline void gpio_nand_dosync(struct gpiomtd *gpiomtd) {}
+#endif
+
+static void gpio_nand_cmd_ctrl(struct mtd_info *mtd, int cmd, unsigned int ctrl)
+{
+	struct gpiomtd *gpiomtd = gpio_nand_getpriv(mtd);
+
+	gpio_nand_dosync(gpiomtd);
+
+	if (ctrl & NAND_CTRL_CHANGE) {
+		gpio_set_value(gpiomtd->plat.gpio_nce, !(ctrl & NAND_NCE));
+		gpio_set_value(gpiomtd->plat.gpio_cle, !!(ctrl & NAND_CLE));
+		gpio_set_value(gpiomtd->plat.gpio_ale, !!(ctrl & NAND_ALE));
+		gpio_nand_dosync(gpiomtd);
+	}
+	if (cmd == NAND_CMD_NONE)
+		return;
+
+	writeb(cmd, gpiomtd->nand_chip.IO_ADDR_W);
+	gpio_nand_dosync(gpiomtd);
+}
+
+static void gpio_nand_writebuf(struct mtd_info *mtd, const u_char *buf, int len)
+{
+	struct nand_chip *this = mtd->priv;
+
+	writesb(this->IO_ADDR_W, buf, len);
+}
+
+static void gpio_nand_readbuf(struct mtd_info *mtd, u_char *buf, int len)
+{
+	struct nand_chip *this = mtd->priv;
+
+	readsb(this->IO_ADDR_R, buf, len);
+}
+
+static int gpio_nand_verifybuf(struct mtd_info *mtd, const u_char *buf, int len)
+{
+	struct nand_chip *this = mtd->priv;
+	unsigned char read, *p = (unsigned char *) buf;
+	int i, err = 0;
+
+	for (i = 0; i < len; i++) {
+		read = readb(this->IO_ADDR_R);
+		if (read != p[i]) {
+			pr_debug("%s: err at %d (read %04x vs %04x)\n",
+			       __func__, i, read, p[i]);
+			err = -EFAULT;
+		}
+	}
+	return err;
+}
+
+static void gpio_nand_writebuf16(struct mtd_info *mtd, const u_char *buf,
+				 int len)
+{
+	struct nand_chip *this = mtd->priv;
+
+	if (IS_ALIGNED((unsigned long)buf, 2)) {
+		writesw(this->IO_ADDR_W, buf, len>>1);
+	} else {
+		int i;
+		unsigned short *ptr = (unsigned short *)buf;
+
+		for (i = 0; i < len; i += 2, ptr++)
+			writew(*ptr, this->IO_ADDR_W);
+	}
+}
+
+static void gpio_nand_readbuf16(struct mtd_info *mtd, u_char *buf, int len)
+{
+	struct nand_chip *this = mtd->priv;
+
+	if (IS_ALIGNED((unsigned long)buf, 2)) {
+		readsw(this->IO_ADDR_R, buf, len>>1);
+	} else {
+		int i;
+		unsigned short *ptr = (unsigned short *)buf;
+
+		for (i = 0; i < len; i += 2, ptr++)
+			*ptr = readw(this->IO_ADDR_R);
+	}
+}
+
+static int gpio_nand_verifybuf16(struct mtd_info *mtd, const u_char *buf,
+				 int len)
+{
+	struct nand_chip *this = mtd->priv;
+	unsigned short read, *p = (unsigned short *) buf;
+	int i, err = 0;
+	len >>= 1;
+
+	for (i = 0; i < len; i++) {
+		read = readw(this->IO_ADDR_R);
+		if (read != p[i]) {
+			pr_debug("%s: err at %d (read %04x vs %04x)\n",
+			       __func__, i, read, p[i]);
+			err = -EFAULT;
+		}
+	}
+	return err;
+}
+
+
+static int gpio_nand_devready(struct mtd_info *mtd)
+{
+	struct gpiomtd *gpiomtd = gpio_nand_getpriv(mtd);
+	return gpio_get_value(gpiomtd->plat.gpio_rdy);
+}
+
+static int __devexit gpio_nand_remove(struct platform_device *dev)
+{
+	struct gpiomtd *gpiomtd = platform_get_drvdata(dev);
+	struct resource *res;
+
+	nand_release(&gpiomtd->mtd_info);
+
+	res = platform_get_resource(dev, IORESOURCE_MEM, 1);
+	iounmap(gpiomtd->io_sync);
+	if (res)
+		release_mem_region(res->start, res->end - res->start + 1);
+
+	res = platform_get_resource(dev, IORESOURCE_MEM, 0);
+	iounmap(gpiomtd->nand_chip.IO_ADDR_R);
+	release_mem_region(res->start, res->end - res->start + 1);
+
+	if (gpio_is_valid(gpiomtd->plat.gpio_nwp))
+		gpio_set_value(gpiomtd->plat.gpio_nwp, 0);
+	gpio_set_value(gpiomtd->plat.gpio_nce, 1);
+
+	gpio_free(gpiomtd->plat.gpio_cle);
+	gpio_free(gpiomtd->plat.gpio_ale);
+	gpio_free(gpiomtd->plat.gpio_nce);
+	if (gpio_is_valid(gpiomtd->plat.gpio_nwp))
+		gpio_free(gpiomtd->plat.gpio_nwp);
+	gpio_free(gpiomtd->plat.gpio_rdy);
+
+	kfree(gpiomtd);
+
+	return 0;
+}
+
+static void __iomem *request_and_remap(struct resource *res, size_t size,
+					const char *name, int *err)
+{
+	void __iomem *ptr;
+
+	if (!request_mem_region(res->start, res->end - res->start + 1, name)) {
+		*err = -EBUSY;
+		return NULL;
+	}
+
+	ptr = ioremap(res->start, size);
+	if (!ptr) {
+		release_mem_region(res->start, res->end - res->start + 1);
+		*err = -ENOMEM;
+	}
+	return ptr;
+}
+
+static int __devinit gpio_nand_probe(struct platform_device *dev)
+{
+	struct gpiomtd *gpiomtd;
+	struct nand_chip *this;
+	struct resource *res0, *res1;
+	int ret;
+
+	if (!dev->dev.platform_data)
+		return -EINVAL;
+
+	res0 = platform_get_resource(dev, IORESOURCE_MEM, 0);
+	if (!res0)
+		return -EINVAL;
+
+	gpiomtd = kzalloc(sizeof(*gpiomtd), GFP_KERNEL);
+	if (gpiomtd == NULL) {
+		dev_err(&dev->dev, "failed to create NAND MTD\n");
+		return -ENOMEM;
+	}
+
+	this = &gpiomtd->nand_chip;
+	this->IO_ADDR_R = request_and_remap(res0, 2, "NAND", &ret);
+	if (!this->IO_ADDR_R) {
+		dev_err(&dev->dev, "unable to map NAND\n");
+		goto err_map;
+	}
+
+	res1 = platform_get_resource(dev, IORESOURCE_MEM, 1);
+	if (res1) {
+		gpiomtd->io_sync = request_and_remap(res1, 4, "NAND sync", &ret);
+		if (!gpiomtd->io_sync) {
+			dev_err(&dev->dev, "unable to map sync NAND\n");
+			goto err_sync;
+		}
+	}
+
+	memcpy(&gpiomtd->plat, dev->dev.platform_data, sizeof(gpiomtd->plat));
+
+	ret = gpio_request(gpiomtd->plat.gpio_nce, "NAND NCE");
+	if (ret)
+		goto err_nce;
+	gpio_direction_output(gpiomtd->plat.gpio_nce, 1);
+	if (gpio_is_valid(gpiomtd->plat.gpio_nwp)) {
+		ret = gpio_request(gpiomtd->plat.gpio_nwp, "NAND NWP");
+		if (ret)
+			goto err_nwp;
+		gpio_direction_output(gpiomtd->plat.gpio_nwp, 1);
+	}
+	ret = gpio_request(gpiomtd->plat.gpio_ale, "NAND ALE");
+	if (ret)
+		goto err_ale;
+	gpio_direction_output(gpiomtd->plat.gpio_ale, 0);
+	ret = gpio_request(gpiomtd->plat.gpio_cle, "NAND CLE");
+	if (ret)
+		goto err_cle;
+	gpio_direction_output(gpiomtd->plat.gpio_cle, 0);
+	ret = gpio_request(gpiomtd->plat.gpio_rdy, "NAND RDY");
+	if (ret)
+		goto err_rdy;
+	gpio_direction_input(gpiomtd->plat.gpio_rdy);
+
+
+	this->IO_ADDR_W  = this->IO_ADDR_R;
+	this->ecc.mode   = NAND_ECC_SOFT;
+	this->options    = gpiomtd->plat.options;
+	this->chip_delay = gpiomtd->plat.chip_delay;
+
+	/* install our routines */
+	this->cmd_ctrl   = gpio_nand_cmd_ctrl;
+	this->dev_ready  = gpio_nand_devready;
+
+	if (this->options & NAND_BUSWIDTH_16) {
+		this->read_buf   = gpio_nand_readbuf16;
+		this->write_buf  = gpio_nand_writebuf16;
+		this->verify_buf = gpio_nand_verifybuf16;
+	} else {
+		this->read_buf   = gpio_nand_readbuf;
+		this->write_buf  = gpio_nand_writebuf;
+		this->verify_buf = gpio_nand_verifybuf;
+	}
+
+	/* set the mtd private data for the nand driver */
+	gpiomtd->mtd_info.priv = this;
+	gpiomtd->mtd_info.owner = THIS_MODULE;
+
+	if (nand_scan(&gpiomtd->mtd_info, 1)) {
+		dev_err(&dev->dev, "no nand chips found?\n");
+		ret = -ENXIO;
+		goto err_wp;
+	}
+
+	if (gpiomtd->plat.adjust_parts)
+		gpiomtd->plat.adjust_parts(&gpiomtd->plat,
+					   gpiomtd->mtd_info.size);
+
+	add_mtd_partitions(&gpiomtd->mtd_info, gpiomtd->plat.parts,
+			   gpiomtd->plat.num_parts);
+	platform_set_drvdata(dev, gpiomtd);
+
+	return 0;
+
+err_wp:
+	if (gpio_is_valid(gpiomtd->plat.gpio_nwp))
+		gpio_set_value(gpiomtd->plat.gpio_nwp, 0);
+	gpio_free(gpiomtd->plat.gpio_rdy);
+err_rdy:
+	gpio_free(gpiomtd->plat.gpio_cle);
+err_cle:
+	gpio_free(gpiomtd->plat.gpio_ale);
+err_ale:
+	if (gpio_is_valid(gpiomtd->plat.gpio_nwp))
+		gpio_free(gpiomtd->plat.gpio_nwp);
+err_nwp:
+	gpio_free(gpiomtd->plat.gpio_nce);
+err_nce:
+	iounmap(gpiomtd->io_sync);
+	if (res1)
+		release_mem_region(res1->start, res1->end - res1->start + 1);
+err_sync:
+	iounmap(gpiomtd->nand_chip.IO_ADDR_R);
+	release_mem_region(res0->start, res0->end - res0->start + 1);
+err_map:
+	kfree(gpiomtd);
+	return ret;
+}
+
+static struct platform_driver gpio_nand_driver = {
+	.probe		= gpio_nand_probe,
+	.remove		= gpio_nand_remove,
+	.driver		= {
+		.name	= "gpio-nand",
+	},
+};
+
+static int __init gpio_nand_init(void)
+{
+	printk(KERN_INFO "GPIO NAND driver, © 2004 Simtec Electronics\n");
+
+	return platform_driver_register(&gpio_nand_driver);
+}
+
+static void __exit gpio_nand_exit(void)
+{
+	platform_driver_unregister(&gpio_nand_driver);
+}
+
+module_init(gpio_nand_init);
+module_exit(gpio_nand_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Ben Dooks <[e-mail]>");
+MODULE_DESCRIPTION("GPIO NAND Driver");

include/linux/mtd/nand-gpio.h

···
+#ifndef __LINUX_MTD_NAND_GPIO_H
+#define __LINUX_MTD_NAND_GPIO_H
+
+#include <linux/mtd/nand.h>
+
+struct gpio_nand_platdata {
+	int	gpio_nce;
+	int	gpio_nwp;
+	int	gpio_cle;
+	int	gpio_ale;
+	int	gpio_rdy;
+	void	(*adjust_parts)(struct gpio_nand_platdata *, size_t);
+	struct mtd_partition *parts;
+	unsigned int num_parts;
+	unsigned int options;
+	int	chip_delay;
+};
+
+#endif