mtd: uclinux: support ROM and allow passing the base address

This allows to put the filesystem at a defined address in ROM allowing
to save more precious RAM.

I think it's safe to default to ROM because the intention of using the
uclinux map is to use a romfs and so mtd-ram doesn't give you anything
that mtd-rom doesn't.

Signed-off-by: Uwe Kleine-König <[e-mail]>
Acked-by: Greg Ungerer <[e-mail]>
Signed-off-by: Artem Bityutskiy <[e-mail]>

drivers/mtd/maps/Kconfig

···
 
 config MTD_UCLINUX
 	bool "Generic uClinux RAM/ROM filesystem support"
-	depends on MTD_RAM=y && (!MMU || COLDFIRE)
+	depends on (MTD_RAM=y || MTD_ROM=y) && (!MMU || COLDFIRE)
 	help
 	  Map driver to support image based filesystems for uClinux.
 

drivers/mtd/maps/uclinux.c

···
 
 /****************************************************************************/
 
+#ifdef CONFIG_MTD_ROM
+#define MAP_NAME "rom"
+#else
+#define MAP_NAME "ram"
+#endif
+
 struct map_info uclinux_ram_map = {
-	.name = "RAM",
-	.phys = (unsigned long)__bss_stop,
+	.name = MAP_NAME,
 	.size = 0,
 };
+
+static unsigned long physaddr = -1;
+module_param(physaddr, ulong, S_IRUGO);
 
 static struct mtd_info *uclinux_ram_mtdinfo;
 
···
 	struct map_info *mapp;
 
 	mapp = &uclinux_ram_map;
+
+	if (physaddr == -1)
+		mapp->phys = (resource_size_t)__bss_stop;
+	else
+		mapp->phys = physaddr;
+
 	if (!mapp->size)
 		mapp->size = PAGE_ALIGN(ntohl(*((unsigned long *)(mapp->phys + 8))));
 	mapp->bankwidth = 4;
 
-	printk("uclinux[mtd]: RAM probe address=0x%x size=0x%x\n",
+	printk("uclinux[mtd]: probe address=0x%x size=0x%x\n",
 	       	(int) mapp->phys, (int) mapp->size);
 
 	/*
···
 
 	simple_map_init(mapp);
 
-	mtd = do_map_probe("map_ram", mapp);
+	mtd = do_map_probe("map_" MAP_NAME, mapp);
 	if (!mtd) {
 		printk("uclinux[mtd]: failed to find a mapping?\n");
 		return(-ENXIO);
···
 
 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Greg Ungerer <[e-mail]>");
-MODULE_DESCRIPTION("Generic RAM based MTD for uClinux");
+MODULE_DESCRIPTION("Generic MTD for uClinux");
 
 /****************************************************************************/