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: John Crispin <blogic@openwrt.org>
Signed-off-by: Ralph 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: Artem Bityutskiy <dedekind1@gmail.com>
Patchwork: https://patchwork.linux-mips.org/patch/2285/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

3 files changed, 259 insertions, 0 deletions

diff --git a/drivers/mtd/maps/Kconfig b/drivers/mtd/maps/Kconfig
index 44b1f46458ca..5069111c81cc 100644
--- a/drivers/mtd/maps/Kconfig
+++ b/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
diff --git a/drivers/mtd/maps/Makefile b/drivers/mtd/maps/Makefile
index 08533bd5cba7..6adf4c9b9057 100644
--- a/drivers/mtd/maps/Makefile
+++ b/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
diff --git a/drivers/mtd/maps/lantiq-flash.c b/drivers/mtd/maps/lantiq-flash.c
new file mode 100644
index 000000000000..a90cabd7b84d
--- /dev/null
+++ b/drivers/mtd/maps/lantiq-flash.c
@@ -0,0 +1,251 @@
+/*
+ *  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");