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From: Sudhakar Rajashekhara on 9 Jul 2010 02:00
From: Sudhakar Rajashekhara <sudhakar....(a)ti.com>

This patch implements memory accessor interface in the MTD
layer which enables the kernel to access flash data.

This patch adds two new members to the mtd_partition structure,
a function handler which will be called during setup of the
partition and an argument to be passed to this setup function.

Example:
+static struct mtd_partition spi_flash_partitions[] = {
+ [0] = {
+ .name = "U-Boot",
+ .offset = 0,
+ .size = SZ_256K,
+ .mask_flags = MTD_WRITEABLE,
+ },
+ [1] = {
+ .name = "U-Boot Environment",
+ .offset = MTDPART_OFS_NXTBLK,
+ .size = SZ_64K,
+ .mask_flags = MTD_WRITEABLE,
+ },
+ [2] = {
+ .name = "Linux",
+ .offset = MTDPART_OFS_NXTBLK,
+ .size = SZ_7M,
+ .mask_flags = 0,
+ },
+ [3] = {
+ .name = "MAC Address",
+ .offset = MTDPART_OFS_NXTBLK,
+ .size = SZ_64K,
+ .mask_flags = 0,
+ .setup = davinci_get_mac_addr,
+ .context = (void *)0,
+ },
+};

The davinci_get_mac_addr function reads the MAC address from
offset ZERO of last MTD partition.

Signed-off-by: Sudhakar Rajashekhara <sudhakar.raj(a)ti.com>
Acked-by: Kevin Hilman <khilman(a)deeprootsystems.com>
Cc: David Brownell <david-b(a)pacbell.net>
Cc: David Woodhouse <dwmw2(a)infradead.org>
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
---
drivers/mtd/mtdpart.c | 40 ++++++++++++++++++++++++++++++++++++++++
include/linux/mtd/partitions.h | 3 +++
2 files changed, 43 insertions(+), 0 deletions(-)

diff --git a/drivers/mtd/mtdpart.c b/drivers/mtd/mtdpart.c
index b8043a9..9f4d5f8 100644
--- a/drivers/mtd/mtdpart.c
+++ b/drivers/mtd/mtdpart.c
@@ -26,6 +26,7 @@ static LIST_HEAD(mtd_partitions);
struct mtd_part {
struct mtd_info mtd;
struct mtd_info *master;
+ struct memory_accessor macc;
uint64_t offset;
struct list_head list;
};
@@ -327,6 +328,39 @@ int del_mtd_partitions(struct mtd_info *master)
}
EXPORT_SYMBOL(del_mtd_partitions);

+/*
+ * This lets other kernel code access the flash data. For example, it
+ * might hold a board's Ethernet address, or board-specific calibration
+ * data generated on the manufacturing floor.
+ */
+static ssize_t mtd_macc_read(struct memory_accessor *macc, char *buf,
+ off_t offset, size_t count)
+{
+ struct mtd_part *part = container_of(macc, struct mtd_part, macc);
+ ssize_t ret = -EIO;
+ size_t retlen;
+
+ if (part_read((struct mtd_info *)part, offset, count,
+ &retlen, buf) == 0)
+ ret = retlen;
+
+ return ret;
+}
+
+static ssize_t mtd_macc_write(struct memory_accessor *macc, const char *buf,
+ off_t offset, size_t count)
+{
+ struct mtd_part *part = container_of(macc, struct mtd_part, macc);
+ ssize_t ret = -EIO;
+ size_t retlen;
+
+ if (part_write((struct mtd_info *)part, offset, count,
+ &retlen, buf) == 0)
+ ret = retlen;
+
+ return ret;
+}
+
static struct mtd_part *add_one_partition(struct mtd_info *master,
const struct mtd_partition *part, int partno,
uint64_t cur_offset)
@@ -364,6 +398,9 @@ static struct mtd_part *add_one_partition(struct mtd_info *master,
slave->mtd.read = part_read;
slave->mtd.write = part_write;

+ slave->macc.read = mtd_macc_read;
+ slave->macc.write = mtd_macc_write;
+
if (master->panic_write)
slave->mtd.panic_write = part_panic_write;

@@ -428,6 +465,9 @@ static struct mtd_part *add_one_partition(struct mtd_info *master,
printk(KERN_NOTICE "0x%012llx-0x%012llx : \"%s\"\n", (unsigned long long)slave->offset,
(unsigned long long)(slave->offset + slave->mtd.size), slave->mtd.name);

+ if (part->setup)
+ part->setup(&slave->macc, (void *)part->context);
+
/* let's do some sanity checks */
if (slave->offset >= master->size) {
/* let's register it anyway to preserve ordering */
diff --git a/include/linux/mtd/partitions.h b/include/linux/mtd/partitions.h
index 274b619..39782a6 100644
--- a/include/linux/mtd/partitions.h
+++ b/include/linux/mtd/partitions.h
@@ -10,6 +10,7 @@
#define MTD_PARTITIONS_H

#include <linux/types.h>
+#include <linux/memory.h>


/*
@@ -40,6 +41,8 @@ struct mtd_partition {
uint64_t offset; /* offset within the master MTD space */
uint32_t mask_flags; /* master MTD flags to mask out for this partition */
struct nand_ecclayout *ecclayout; /* out of band layout for this partition (NAND only)*/
+ void (*setup)(struct memory_accessor *, void *context);
+ void *context;
};

#define MTDPART_OFS_NXTBLK (-2)
--
1.5.6

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