MIPS: BCM47XX: Use mtd as an alternative way/API to get NVRAM content

NVRAM can be read using magic memory offset, but after all it's just a
flash partition. On platforms where NVRAM isn't needed early we can get
it using mtd subsystem.

Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Acked-by: Hauke Mehrtens <hauke@hauke-m.de>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/8266/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

diff --git a/arch/mips/bcm47xx/nvram.c b/arch/mips/bcm47xx/nvram.c
index 21712fb..8b64991 100644 (file)
--- a/arch/mips/bcm47xx/nvram.c
+++ b/arch/mips/bcm47xx/nvram.c
@@ -13,12 +13,10 @@
 
 #include <linux/types.h>
 #include <linux/module.h>
-#include <linux/ssb/ssb.h>
 #include <linux/kernel.h>
 #include <linux/string.h>
-#include <asm/addrspace.h>
+#include <linux/mtd/mtd.h>
 #include <bcm47xx_nvram.h>
-#include <asm/mach-bcm47xx/bcm47xx.h>
 
 static char nvram_buf[NVRAM_SPACE];
 static const u32 nvram_sizes[] = {0x8000, 0xF000, 0x10000};
@@ -123,7 +121,43 @@ int bcm47xx_nvram_init_from_mem(u32 base, u32 lim)
 
 static int nvram_init(void)
 {
-       /* TODO: Look for MTD "nvram" partition */
+#ifdef CONFIG_MTD
+       struct mtd_info *mtd;
+       struct nvram_header header;
+       size_t bytes_read;
+       int err, i;
+
+       mtd = get_mtd_device_nm("nvram");
+       if (IS_ERR(mtd))
+               return -ENODEV;
+
+       for (i = 0; i < ARRAY_SIZE(nvram_sizes); i++) {
+               loff_t from = mtd->size - nvram_sizes[i];
+
+               if (from < 0)
+                       continue;
+
+               err = mtd_read(mtd, from, sizeof(header), &bytes_read,
+                              (uint8_t *)&header);
+               if (!err && header.magic == NVRAM_HEADER) {
+                       u8 *dst = (uint8_t *)nvram_buf;
+                       size_t len = header.len;
+
+                       if (header.len > NVRAM_SPACE) {
+                               pr_err("nvram on flash (%i bytes) is bigger than the reserved space in memory, will just copy the first %i bytes\n",
+                                      header.len, NVRAM_SPACE);
+                               len = NVRAM_SPACE;
+                       }
+
+                       err = mtd_read(mtd, from, len, &bytes_read, dst);
+                       if (err)
+                               return err;
+                       memset(dst + bytes_read, 0x0, NVRAM_SPACE - bytes_read);
+
+                       return 0;
+               }
+       }
+#endif
 
        return -ENXIO;
 }