[PATCH 1/2 v3] mtd/uclinux: support ROM and allow passing the base address

[Uwe Kleine-König]

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.

Just in case I missed something a warning is added if the driver has to
fall back to the RAM mapping.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig at pengutronix.de>
---
Changes since v2, id:1350027693-19528-1-git-send-email-u.kleine-koenig at pengutronix.de:

 - drop a few "ram"s from printks instead of making them "ram/rom"
 - fix a typo in the commit log and add rational for the introduced warning.

Who is responsible for taking (or not) these two patches? David? Artem?

Best regards
Uwe

---
 drivers/mtd/maps/Kconfig   |    2 +-
 drivers/mtd/maps/uclinux.c |   26 +++++++++++++++++++++-----
 2 files changed, 22 insertions(+), 6 deletions(-)

diff --git a/drivers/mtd/maps/Kconfig b/drivers/mtd/maps/Kconfig
index 2e47c2e..0dc86fc 100644
--- a/drivers/mtd/maps/Kconfig
+++ b/drivers/mtd/maps/Kconfig
@@ -443,7 +443,7 @@ config MTD_GPIO_ADDR
 
 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.
 
diff --git a/drivers/mtd/maps/uclinux.c b/drivers/mtd/maps/uclinux.c
index 299bf88..b3a9c54 100644
--- a/drivers/mtd/maps/uclinux.c
+++ b/drivers/mtd/maps/uclinux.c
@@ -24,11 +24,12 @@
 /****************************************************************************/
 
 struct map_info uclinux_ram_map = {
-	.name = "RAM",
-	.phys = (unsigned long)__bss_stop,
 	.size = 0,
 };
 
+static unsigned long physaddr = -1;
+module_param(physaddr, ulong, S_IRUGO);
+
 static struct mtd_info *uclinux_ram_mtdinfo;
 
 /****************************************************************************/
@@ -60,11 +61,17 @@ static int __init uclinux_mtd_init(void)
 	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);
 
 	/*
@@ -82,7 +89,16 @@ static int __init uclinux_mtd_init(void)
 
 	simple_map_init(mapp);
 
-	mtd = do_map_probe("map_ram", mapp);
+	mapp->name = "ROM";
+	mtd = do_map_probe("map_rom", mapp);
+	if (!mtd) {
+		/* fall back to ram probing for compatibility reasons */
+		mapp->name = "RAM";
+		mtd = do_map_probe("map_ram", mapp);
+		if (mtd && IS_ENABLED(CONFIG_MTD_ROM))
+			pr_err("Failed to map rom, but ram succeeded. Please report this issue!\n");
+	}
+
 	if (!mtd) {
 		printk("uclinux[mtd]: failed to find a mapping?\n");
 		return(-ENXIO);
@@ -118,6 +134,6 @@ module_exit(uclinux_mtd_cleanup);
 
 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Greg Ungerer <gerg at snapgear.com>");
-MODULE_DESCRIPTION("Generic RAM based MTD for uClinux");
+MODULE_DESCRIPTION("Generic MTD for uClinux");
 
 /****************************************************************************/
-- 
1.7.10.4