Patchwork [1/2] mtdpart: memory accessor interface for MTD layer

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Submitter Andrew Morton
Date Oct. 1, 2010, 9:16 p.m.
Message ID <201010012116.o91LGRGn021118@imap1.linux-foundation.org>
Download mbox | patch
Permalink /patch/66519/
State New
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Comments

Andrew Morton - Oct. 1, 2010, 9:16 p.m.
From: Sudhakar Rajashekhara <sudhakar.raj@ti.com>

Implement a 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@ti.com>
Acked-by: Kevin Hilman <khilman@deeprootsystems.com>
Cc: David Brownell <david-b@pacbell.net>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Anton Vorontsov <cbouatmailru@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 drivers/mtd/mtdpart.c          |   40 +++++++++++++++++++++++++++++++
 include/linux/mtd/partitions.h |    3 ++
 2 files changed, 43 insertions(+)
Artem Bityutskiy - Oct. 2, 2010, 2:09 p.m.
On Fri, 2010-10-01 at 14:16 -0700, akpm@linux-foundation.org wrote:
> From: Sudhakar Rajashekhara <sudhakar.raj@ti.com>
> 
> Implement a 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.

This patch does not apply to my l2-mtd-2.6.git tree - many confilicts.
Sudhakar, you can refresh your patch against my tree and re-send:

http://git.infradead.org/users/dedekind/l2-mtd-2.6.git
David Woodhouse - Oct. 2, 2010, 2:44 p.m.
On Sat, 2010-10-02 at 17:09 +0300, Artem Bityutskiy wrote:
> 
> > Implement a 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.
> 
> This patch does not apply to my l2-mtd-2.6.git tree

Wasn't there going to be a much nicer version of this patch coming
anyway?
Andrew Morton - Oct. 2, 2010, 7:09 p.m.
On Sat, 02 Oct 2010 17:09:52 +0300 Artem Bityutskiy <dedekind1@gmail.com> wrote:

> On Fri, 2010-10-01 at 14:16 -0700, akpm@linux-foundation.org wrote:
> > From: Sudhakar Rajashekhara <sudhakar.raj@ti.com>
> > 
> > Implement a 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.
> 
> This patch does not apply to my l2-mtd-2.6.git tree - many confilicts.

It applies against linux-next.

For heavens sake guys, please fix this.
Rajashekhara, Sudhakar - Oct. 4, 2010, 2:28 p.m.
All,

On Sat, Oct 02, 2010 at 20:14:32, David Woodhouse wrote:
> On Sat, 2010-10-02 at 17:09 +0300, Artem Bityutskiy wrote:
> > 
> > > Implement a 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.
> > 
> > This patch does not apply to my l2-mtd-2.6.git tree
> 
> Wasn't there going to be a much nicer version of this patch coming
> anyway?
> 

This patch can be dropped. Please see the discussion at [1] regarding this.

[1] http://lists.infradead.org/pipermail/linux-mtd/2010-August/031483.html

Thanks,
Sudhakar

Patch

diff -puN drivers/mtd/mtdpart.c~mtdpart-memory-accessor-interface-for-mtd-layer drivers/mtd/mtdpart.c
--- a/drivers/mtd/mtdpart.c~mtdpart-memory-accessor-interface-for-mtd-layer
+++ a/drivers/mtd/mtdpart.c
@@ -37,6 +37,7 @@  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;
 };
@@ -346,6 +347,39 @@  int del_mtd_partitions(struct mtd_info *
 }
 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)
@@ -383,6 +417,9 @@  static struct mtd_part *add_one_partitio
 	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;
 
@@ -449,6 +486,9 @@  static struct mtd_part *add_one_partitio
 	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 -puN include/linux/mtd/partitions.h~mtdpart-memory-accessor-interface-for-mtd-layer include/linux/mtd/partitions.h
--- a/include/linux/mtd/partitions.h~mtdpart-memory-accessor-interface-for-mtd-layer
+++ a/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)