[PATCH] Add a map_sram driver to drivers/chips/

[Ian Campbell <icampbell@arcomcontrols.com>]

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Howdy,

The attached patch adds "map_sram" as a second chip driver in
drivers/mtd/chips/map_ram.c.  The two are basically identical apart from
the use of the MTD_VOLATILE flag.

I have another patch which makes an entirely separate map_sram.c, but
there was so much code duplication with map_ram.c I didn't see the
point. I guess if you are using modules then you will need 'alias
map_sram map_ram' in /etc/modules.conf or something to get autoloading
to work.

The patch also includes a previous patch to set the state to
MTD_ERASE_DONE in mapram_erase. This is needed to mount a JFFS2 f/s on
an SRAM or RAM device.

Cheers,
Ian.

-- 
Ian Campbell
Design Engineer

Arcom Control Systems Ltd,
Clifton Road,
Cambridge CB1 7EA
United Kingdom

Tel: +44 (0)1223 403465
E-Mail: icampbell@arcomcontrols.com
Web: http://www.arcomcontrols.com


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[-- Attachment #2: mtd.map_sram-2.patch --]
[-- Type: text/x-patch, Size: 3370 bytes --]

diff -urN kernel-2.4.18.orig/include/linux/mtd/mtd.h kernel-2.4.18/include/linux/mtd/mtd.h
--- kernel-2.4.18.orig/include/linux/mtd/mtd.h	Tue Jun 12 18:30:27 2001
+++ kernel-2.4.18/include/linux/mtd/mtd.h	Wed Nov  6 14:05:30 2002
@@ -39,5 +39,6 @@
 #define MTD_NORFLASH		3
 #define MTD_NANDFLASH		4
 #define MTD_PEROM		5
+#define MTD_SRAM		6
 #define MTD_OTHER		14
 #define MTD_UNKNOWN		15
diff -urN kernel-2.4.18.orig/drivers/mtd/chips/Config.in kernel-2.4.18/drivers/mtd/chips/Config.in
--- kernel-2.4.18.orig/drivers/mtd/chips/Config.in	Thu Oct  4 23:13:18 2001
+++ kernel-2.4.18/drivers/mtd/chips/Config.in	Tue Nov 12 10:29:27 2002
@@ -44,7 +44,7 @@
 dep_tristate '  Support for Intel/Sharp flash chips' CONFIG_MTD_CFI_INTELEXT $CONFIG_MTD_GEN_PROBE
 dep_tristate '  Support for AMD/Fujitsu flash chips' CONFIG_MTD_CFI_AMDSTD $CONFIG_MTD_GEN_PROBE
 
-dep_tristate '  Support for RAM chips in bus mapping' CONFIG_MTD_RAM $CONFIG_MTD
+dep_tristate '  Support for RAM/SRAM chips in bus mapping' CONFIG_MTD_RAM $CONFIG_MTD
 dep_tristate '  Support for ROM chips in bus mapping' CONFIG_MTD_ROM $CONFIG_MTD
 dep_tristate '  Support for absent chips in bus mapping' CONFIG_MTD_ABSENT $CONFIG_MTD
 
diff -urN kernel-2.4.18.orig/drivers/mtd/chips/map_ram.c kernel-2.4.18/drivers/mtd/chips/map_ram.c
--- kernel-2.4.18.orig/drivers/mtd/chips/map_ram.c	Thu Oct  4 23:14:59 2001
+++ kernel-2.4.18/drivers/mtd/chips/map_ram.c	Tue Nov 12 10:52:11 2002
@@ -20,6 +20,7 @@
 static int mapram_erase (struct mtd_info *, struct erase_info *);
 static void mapram_nop (struct mtd_info *);
 static struct mtd_info *map_ram_probe(struct map_info *map);
+static struct mtd_info *map_sram_probe(struct map_info *map);
 
 
 static struct mtd_chip_driver mapram_chipdrv = {
@@ -27,6 +28,11 @@
 	name: "map_ram",
 	module: THIS_MODULE
 };
+static struct mtd_chip_driver mapsram_chipdrv = {
+	probe: map_sram_probe,
+	name: "map_sram",
+	module: THIS_MODULE
+};
 
 static struct mtd_info *map_ram_probe(struct map_info *map)
 {
@@ -78,6 +84,34 @@
 	return mtd;
 }
 
+static struct mtd_info *map_sram_probe(struct map_info *map)
+{
+	struct mtd_info *mtd;
+
+	mtd = kmalloc(sizeof(*mtd), GFP_KERNEL);
+	if (!mtd)
+		return NULL;
+
+	memset(mtd, 0, sizeof(*mtd));
+
+	map->fldrv = &mapram_chipdrv;
+	mtd->priv = map;
+	mtd->name = map->name;
+	mtd->type = MTD_SRAM;
+	mtd->size = map->size;
+	mtd->erase = mapram_erase;
+	mtd->read = mapram_read;
+	mtd->write = mapram_write;
+	mtd->sync = mapram_nop;
+	mtd->flags = MTD_CAP_RAM;
+
+	mtd->erasesize = PAGE_SIZE;
+ 	while(mtd->size & (mtd->erasesize - 1))
+		mtd->erasesize >>= 1;
+
+	MOD_INC_USE_COUNT;
+	return mtd;
+}
 
 static int mapram_read (struct mtd_info *mtd, loff_t from, size_t len, size_t *retlen, u_char *buf)
 {
@@ -107,6 +141,8 @@
 	for (i=0; i<instr->len; i++)
 		map->write8(map, 0xFF, instr->addr + i);
 
+	instr->state = MTD_ERASE_DONE;
+
 	if (instr->callback)
 		instr->callback(instr);
 
@@ -121,12 +157,14 @@
 int __init map_ram_init(void)
 {
 	register_mtd_chip_driver(&mapram_chipdrv);
+	register_mtd_chip_driver(&mapsram_chipdrv);
 	return 0;
 }
 
 static void __exit map_ram_exit(void)
 {
 	unregister_mtd_chip_driver(&mapram_chipdrv);
+	unregister_mtd_chip_driver(&mapsram_chipdrv);
 }
 
 module_init(map_ram_init);