MIPS: Lantiq: Add NOR flash support

This patch adds the driver/map for NOR devices attached to the SoC via the
External Bus Unit (EBU).
Signed-off-by: NJohn Crispin <blogic@openwrt.org>
Signed-off-by: NRalph Hempel <ralph.hempel@lantiq.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Daniel Schwierzeck <daniel.schwierzeck@googlemail.com>
Cc: linux-mips@linux-mips.org
Cc: linux-mtd@lists.infradead.org
Acked-by: NArtem Bityutskiy <dedekind1@gmail.com>
Patchwork: https://patchwork.linux-mips.org/patch/2285/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

drivers/mtd/maps/Kconfig

@@ -260,6 +260,13 @@ config MTD_BCM963XX
 	  Support for parsing CFE image tag and creating MTD partitions on
 	  Broadcom BCM63xx boards.
 
+config MTD_LANTIQ
+	tristate "Lantiq SoC NOR support"
+	depends on LANTIQ
+	select MTD_PARTITIONS
+	help
+	  Support for NOR flash attached to the Lantiq SoC's External Bus Unit.
+
 config MTD_DILNETPC
 	tristate "CFI Flash device mapped on DIL/Net PC"
 	depends on X86 && MTD_PARTITIONS && MTD_CFI_INTELEXT && BROKEN

drivers/mtd/maps/Makefile

@@ -60,3 +60,4 @@ obj-$(CONFIG_MTD_VMU)		+= vmu-flash.o
 obj-$(CONFIG_MTD_GPIO_ADDR)	+= gpio-addr-flash.o
 obj-$(CONFIG_MTD_BCM963XX)	+= bcm963xx-flash.o
 obj-$(CONFIG_MTD_LATCH_ADDR)	+= latch-addr-flash.o
+obj-$(CONFIG_MTD_LANTIQ)	+= lantiq-flash.o

drivers/mtd/maps/lantiq-flash.c

+/*
+ *  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.
+ *
+ *  Copyright (C) 2004 Liu Peng Infineon IFAP DC COM CPE
+ *  Copyright (C) 2010 John Crispin <blogic@openwrt.org>
+ */
+
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/io.h>
+#include <linux/slab.h>
+#include <linux/init.h>
+#include <linux/mtd/mtd.h>
+#include <linux/mtd/map.h>
+#include <linux/mtd/partitions.h>
+#include <linux/mtd/cfi.h>
+#include <linux/platform_device.h>
+#include <linux/mtd/physmap.h>
+
+#include <lantiq_soc.h>
+#include <lantiq_platform.h>
+
+/*
+ * The NOR flash is connected to the same external bus unit (EBU) as PCI.
+ * To make PCI work we need to enable the endianness swapping for the address
+ * written to the EBU. This endianness swapping works for PCI correctly but
+ * fails for attached NOR devices. To workaround this we need to use a complex
+ * map. The workaround involves swapping all addresses whilst probing the chip.
+ * Once probing is complete we stop swapping the addresses but swizzle the
+ * unlock addresses to ensure that access to the NOR device works correctly.
+ */
+
+enum {
+	LTQ_NOR_PROBING,
+	LTQ_NOR_NORMAL
+};
+
+struct ltq_mtd {
+	struct resource *res;
+	struct mtd_info *mtd;
+	struct map_info *map;
+};
+
+static char ltq_map_name[] = "ltq_nor";
+
+static map_word
+ltq_read16(struct map_info *map, unsigned long adr)
+{
+	unsigned long flags;
+	map_word temp;
+
+	if (map->map_priv_1 == LTQ_NOR_PROBING)
+		adr ^= 2;
+	spin_lock_irqsave(&ebu_lock, flags);
+	temp.x[0] = *(u16 *)(map->virt + adr);
+	spin_unlock_irqrestore(&ebu_lock, flags);
+	return temp;
+}
+
+static void
+ltq_write16(struct map_info *map, map_word d, unsigned long adr)
+{
+	unsigned long flags;
+
+	if (map->map_priv_1 == LTQ_NOR_PROBING)
+		adr ^= 2;
+	spin_lock_irqsave(&ebu_lock, flags);
+	*(u16 *)(map->virt + adr) = d.x[0];
+	spin_unlock_irqrestore(&ebu_lock, flags);
+}
+
+/*
+ * The following 2 functions copy data between iomem and a cached memory
+ * section. As memcpy() makes use of pre-fetching we cannot use it here.
+ * The normal alternative of using memcpy_{to,from}io also makes use of
+ * memcpy() on MIPS so it is not applicable either. We are therefore stuck
+ * with having to use our own loop.
+ */
+static void
+ltq_copy_from(struct map_info *map, void *to,
+	unsigned long from, ssize_t len)
+{
+	unsigned char *f = (unsigned char *)map->virt + from;
+	unsigned char *t = (unsigned char *)to;
+	unsigned long flags;
+
+	spin_lock_irqsave(&ebu_lock, flags);
+	while (len--)
+		*t++ = *f++;
+	spin_unlock_irqrestore(&ebu_lock, flags);
+}
+
+static void
+ltq_copy_to(struct map_info *map, unsigned long to,
+	const void *from, ssize_t len)
+{
+	unsigned char *f = (unsigned char *)from;
+	unsigned char *t = (unsigned char *)map->virt + to;
+	unsigned long flags;
+
+	spin_lock_irqsave(&ebu_lock, flags);
+	while (len--)
+		*t++ = *f++;
+	spin_unlock_irqrestore(&ebu_lock, flags);
+}
+
+static const char const *part_probe_types[] = { "cmdlinepart", NULL };
+
+static int __init
+ltq_mtd_probe(struct platform_device *pdev)
+{
+	struct physmap_flash_data *ltq_mtd_data = dev_get_platdata(&pdev->dev);
+	struct ltq_mtd *ltq_mtd;
+	struct mtd_partition *parts;
+	struct resource *res;
+	int nr_parts = 0;
+	struct cfi_private *cfi;
+	int err;
+
+	ltq_mtd = kzalloc(sizeof(struct ltq_mtd), GFP_KERNEL);
+	platform_set_drvdata(pdev, ltq_mtd);
+
+	ltq_mtd->res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!ltq_mtd->res) {
+		dev_err(&pdev->dev, "failed to get memory resource");
+		err = -ENOENT;
+		goto err_out;
+	}
+
+	res = devm_request_mem_region(&pdev->dev, ltq_mtd->res->start,
+		resource_size(ltq_mtd->res), dev_name(&pdev->dev));
+	if (!ltq_mtd->res) {
+		dev_err(&pdev->dev, "failed to request mem resource");
+		err = -EBUSY;
+		goto err_out;
+	}
+
+	ltq_mtd->map = kzalloc(sizeof(struct map_info), GFP_KERNEL);
+	ltq_mtd->map->phys = res->start;
+	ltq_mtd->map->size = resource_size(res);
+	ltq_mtd->map->virt = devm_ioremap_nocache(&pdev->dev,
+				ltq_mtd->map->phys, ltq_mtd->map->size);
+	if (!ltq_mtd->map->virt) {
+		dev_err(&pdev->dev, "failed to ioremap!\n");
+		err = -ENOMEM;
+		goto err_free;
+	}
+
+	ltq_mtd->map->name = ltq_map_name;
+	ltq_mtd->map->bankwidth = 2;
+	ltq_mtd->map->read = ltq_read16;
+	ltq_mtd->map->write = ltq_write16;
+	ltq_mtd->map->copy_from = ltq_copy_from;
+	ltq_mtd->map->copy_to = ltq_copy_to;
+
+	ltq_mtd->map->map_priv_1 = LTQ_NOR_PROBING;
+	ltq_mtd->mtd = do_map_probe("cfi_probe", ltq_mtd->map);
+	ltq_mtd->map->map_priv_1 = LTQ_NOR_NORMAL;
+
+	if (!ltq_mtd->mtd) {
+		dev_err(&pdev->dev, "probing failed\n");
+		err = -ENXIO;
+		goto err_unmap;
+	}
+
+	ltq_mtd->mtd->owner = THIS_MODULE;
+
+	cfi = ltq_mtd->map->fldrv_priv;
+	cfi->addr_unlock1 ^= 1;
+	cfi->addr_unlock2 ^= 1;
+
+	nr_parts = parse_mtd_partitions(ltq_mtd->mtd,
+				part_probe_types, &parts, 0);
+	if (nr_parts > 0) {
+		dev_info(&pdev->dev,
+			"using %d partitions from cmdline", nr_parts);
+	} else {
+		nr_parts = ltq_mtd_data->nr_parts;
+		parts = ltq_mtd_data->parts;
+	}
+
+	err = add_mtd_partitions(ltq_mtd->mtd, parts, nr_parts);
+	if (err) {
+		dev_err(&pdev->dev, "failed to add partitions\n");
+		goto err_destroy;
+	}
+
+	return 0;
+
+err_destroy:
+	map_destroy(ltq_mtd->mtd);
+err_unmap:
+	iounmap(ltq_mtd->map->virt);
+err_free:
+	kfree(ltq_mtd->map);
+err_out:
+	kfree(ltq_mtd);
+	return err;
+}
+
+static int __devexit
+ltq_mtd_remove(struct platform_device *pdev)
+{
+	struct ltq_mtd *ltq_mtd = platform_get_drvdata(pdev);
+
+	if (ltq_mtd) {
+		if (ltq_mtd->mtd) {
+			del_mtd_partitions(ltq_mtd->mtd);
+			map_destroy(ltq_mtd->mtd);
+		}
+		if (ltq_mtd->map->virt)
+			iounmap(ltq_mtd->map->virt);
+		kfree(ltq_mtd->map);
+		kfree(ltq_mtd);
+	}
+	return 0;
+}
+
+static struct platform_driver ltq_mtd_driver = {
+	.remove = __devexit_p(ltq_mtd_remove),
+	.driver = {
+		.name = "ltq_nor",
+		.owner = THIS_MODULE,
+	},
+};
+
+static int __init
+init_ltq_mtd(void)
+{
+	int ret = platform_driver_probe(&ltq_mtd_driver, ltq_mtd_probe);
+
+	if (ret)
+		pr_err("ltq_nor: error registering platform driver");
+	return ret;
+}
+
+static void __exit
+exit_ltq_mtd(void)
+{
+	platform_driver_unregister(&ltq_mtd_driver);
+}
+
+module_init(init_ltq_mtd);
+module_exit(exit_ltq_mtd);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("John Crispin <blogic@openwrt.org>");
+MODULE_DESCRIPTION("Lantiq SoC NOR");