Document and implement an improved flash device binding for powerpc
David Gibson
david at gibson.dropbear.id.au
Tue Aug 28 13:47:51 EST 2007
This patch replaces the binding for flash chips in
booting-without-of.txt with an clarified and improved version. It
also makes drivers/mtd/maps/physmap_of.c recognize this new binding.
Finally it revises the Ebony device tree source to use the new binding
as an example.
Signed-off-by: David Gibson <david at gibson.dropbear.id.au>
---
I don't know that this is ready yet, but I thought I'd try to kick
along the rather stalled process of getting this new flash binding in
place by sending out my current draft.
Index: working-2.6/Documentation/powerpc/booting-without-of.txt
===================================================================
--- working-2.6.orig/Documentation/powerpc/booting-without-of.txt 2007-08-28 13:25:42.000000000 +1000
+++ working-2.6/Documentation/powerpc/booting-without-of.txt 2007-08-28 13:38:10.000000000 +1000
@@ -1757,45 +1757,46 @@ platforms are moved over to use the flat
};
};
- j) Flash chip nodes
+ j) CFI or JEDEC memory-mapped NOR flash
Flash chips (Memory Technology Devices) are often used for solid state
file systems on embedded devices.
- Required properties:
-
- - device_type : has to be "rom"
- - compatible : Should specify what this flash device is compatible with.
- Currently, this is most likely to be "direct-mapped" (which
- corresponds to the MTD physmap mapping driver).
- - reg : Offset and length of the register set (or memory mapping) for
- the device.
- - bank-width : Width of the flash data bus in bytes. Required
- for the NOR flashes (compatible == "direct-mapped" and others) ONLY.
-
- Recommended properties :
-
- - partitions : Several pairs of 32-bit values where the first value is
- partition's offset from the start of the device and the second one is
- partition size in bytes with LSB used to signify a read only
- partition (so, the partition size should always be an even number).
- - partition-names : The list of concatenated zero terminated strings
- representing the partition names.
- - probe-type : The type of probe which should be done for the chip
- (JEDEC vs CFI actually). Valid ONLY for NOR flashes.
-
- Example:
-
- flash at ff000000 {
- device_type = "rom";
- compatible = "direct-mapped";
- probe-type = "CFI";
- reg = <ff000000 01000000>;
- bank-width = <4>;
- partitions = <00000000 00f80000
- 00f80000 00080001>;
- partition-names = "fs\0firmware";
- };
+ - compatible : should contain the specific model of flash chip(s)
+ used, if known, followed by either "cfi-flash" or "jedec-flash"
+ - reg : Address range of the flash chip
+ - bank-width : Width (in bytes) of the flash bank. Equal to the
+ device width times the number of interleaved chips.
+ - device-width : (optional) Width of a single flash chip. If
+ omitted, assumed to be equal to 'bank-width'.
+ - #address-cells, #size-cells : Must be present if the flash has
+ sub-nodes representing partitions (see below). In this case
+ both #address-cells and #size-cells must be equal to 1.
+
+ For JEDEC compatible devices, the following additional properties
+ are defined:
+
+ - vendor-id : Contains the flash chip's vendor id (1 byte).
+ - device-id : Contains the flash chip's device id (1 byte).
+
+ In addition to the information on the flash bank itself, the
+ device tree may optionally contain additional information
+ describing partitions of the flash address space. This can be
+ used on platforms which have strong conventions about which
+ portions of the flash are used for what purposes, but which don't
+ use an on-flash partition table such as RedBoot.
+
+ Each partitions is represented as a sub-node of the flash device.
+ Each node's name represents the name of the corresponding
+ partition of the flash device.
+
+ Flash partitions
+ - reg : The partition's offset and size within the flash bank.
+ - read-only : (optional) This parameter, if present, is a hint to
+ Linux that this flash partition should only be mounted
+ read-only. This is usually used for flash partitions
+ containing early-boot firmware images or data which should not
+ be clobbered.
k) Global Utilities Block
Index: working-2.6/drivers/mtd/maps/physmap_of.c
===================================================================
--- working-2.6.orig/drivers/mtd/maps/physmap_of.c 2007-08-28 13:25:42.000000000 +1000
+++ working-2.6/drivers/mtd/maps/physmap_of.c 2007-08-28 13:26:43.000000000 +1000
@@ -4,6 +4,9 @@
* Copyright (C) 2006 MontaVista Software Inc.
* Author: Vitaly Wool <vwool at ru.mvista.com>
*
+ * Revised to handle newer style flash binding by:
+ * Copyright (C) 2007 David Gibson, IBM Corporation.
+ *
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2 of the License, or (at your
@@ -30,56 +33,129 @@ struct physmap_flash_info {
struct map_info map;
struct resource *res;
#ifdef CONFIG_MTD_PARTITIONS
- int nr_parts;
struct mtd_partition *parts;
#endif
};
-static const char *rom_probe_types[] = { "cfi_probe", "jedec_probe", "map_rom", NULL };
-#ifdef CONFIG_MTD_PARTITIONS
-static const char *part_probe_types[] = { "cmdlinepart", "RedBoot", NULL };
-#endif
-
#ifdef CONFIG_MTD_PARTITIONS
-static int parse_flash_partitions(struct device_node *node,
- struct mtd_partition **parts)
+static int parse_obsolete_partitions(struct physmap_flash_info *info,
+ struct device_node *dp)
{
- int i, plen, retval = -ENOMEM;
- const u32 *part;
- const char *name;
-
- part = of_get_property(node, "partitions", &plen);
- if (part == NULL)
- goto err;
-
- retval = plen / (2 * sizeof(u32));
- *parts = kzalloc(retval * sizeof(struct mtd_partition), GFP_KERNEL);
- if (*parts == NULL) {
+ int i, plen, nr_parts;
+ const struct {
+ u32 offset, len;
+ } *part;
+ const char *names;
+
+ part = of_get_property(dp, "partitions", &plen);
+ if (!part)
+ return -ENOENT;
+
+ nr_parts = plen / sizeof(part[0]);
+
+ info->parts = kzalloc(nr_parts * sizeof(struct mtd_partition), GFP_KERNEL);
+ if (!info->parts) {
printk(KERN_ERR "Can't allocate the flash partition data!\n");
- goto err;
+ return -ENOMEM;
}
- name = of_get_property(node, "partition-names", &plen);
+ names = of_get_property(dp, "partition-names", &plen);
- for (i = 0; i < retval; i++) {
- (*parts)[i].offset = *part++;
- (*parts)[i].size = *part & ~1;
- if (*part++ & 1) /* bit 0 set signifies read only partition */
- (*parts)[i].mask_flags = MTD_WRITEABLE;
+ for (i = 0; i < nr_parts; i++) {
+ info->parts[i].offset = part->offset;
+ info->parts[i].size = part->len & ~1;
+ if (part->len & 1) /* bit 0 set signifies read only partition */
+ info->parts[i].mask_flags = MTD_WRITEABLE;
- if (name != NULL && plen > 0) {
- int len = strlen(name) + 1;
+ if (names && (plen > 0)) {
+ int len = strlen(names) + 1;
- (*parts)[i].name = (char *)name;
+ info->parts[i].name = (char *)names;
plen -= len;
- name += len;
- } else
- (*parts)[i].name = "unnamed";
+ names += len;
+ } else {
+ info->parts[i].name = "unnamed";
+ }
+
+ part++;
}
-err:
- return retval;
+
+ return nr_parts;
}
-#endif
+
+static int __devinit process_partitions(struct physmap_flash_info *info,
+ struct of_device *dev)
+{
+ static const char *part_probe_types[]
+ = { "cmdlinepart", "RedBoot", NULL };
+ struct device_node *dp = dev->node, *pp;
+ int nr_parts, i, err;
+
+ /* First look for RedBoot table or partitions on the command
+ * line, these take precedence over device tree information */
+ nr_parts = parse_mtd_partitions(info->mtd, part_probe_types,
+ &info->parts, 0);
+ if (nr_parts > 0) {
+ add_mtd_partitions(info->mtd, info->parts, err);
+ return 0;
+ }
+
+ /* First count the subnodes */
+ nr_parts = 0;
+ for (pp = dp->child; pp; pp = pp->sibling)
+ nr_parts++;
+
+ if (nr_parts) {
+ info->parts = kzalloc(nr_parts * sizeof(struct mtd_partition),
+ GFP_KERNEL);
+ if (!info->parts) {
+ printk(KERN_ERR "Can't allocate the flash partition data!\n");
+ return -ENOMEM;
+ }
+
+ for (pp = dp->child, i = 0 ; pp; pp = pp->sibling, i++) {
+ const u32 *reg;
+ int len;
+
+ reg = of_get_property(pp, "reg", &len);
+ if (!reg || (len != 2*sizeof(u32))) {
+ dev_err(&dev->dev, "Invalid 'reg' on %s\n",
+ dp->full_name);
+ kfree(info->parts);
+ info->parts = NULL;
+ return -EINVAL;
+ }
+ info->parts[i].offset = reg[0];
+ info->parts[i].size = reg[1];
+
+ info->parts[i].name =
+ (char *)of_get_property(pp, "name", &len);
+
+ if (of_get_property(pp, "read-only", &len))
+ info->parts[i].mask_flags = MTD_WRITEABLE;
+ }
+ } else {
+ nr_parts = parse_obsolete_partitions(info, dp);
+ }
+
+ if (nr_parts < 0)
+ return nr_parts;
+
+ if (nr_parts > 0)
+ add_mtd_partitions(info->mtd, info->parts, nr_parts);
+ else
+ add_mtd_device(info->mtd);
+
+ return 0;
+}
+#else /* MTD_PARTITIONS */
+static int __devinit process_partitions(struct physmap_flash_info *info,
+ struct device_node *dev)
+{
+ add_mtd_device(info->mtd);
+ return 0;
+}
+#endif /* MTD_PARTITIONS */
static int of_physmap_remove(struct of_device *dev)
{
@@ -92,7 +168,7 @@ static int of_physmap_remove(struct of_d
if (info->mtd != NULL) {
#ifdef CONFIG_MTD_PARTITIONS
- if (info->nr_parts) {
+ if (info->parts) {
del_mtd_partitions(info->mtd);
kfree(info->parts);
} else {
@@ -115,13 +191,45 @@ static int of_physmap_remove(struct of_d
return 0;
}
+/* Helper function to handle probing of the obsolete "direct-mapped"
+ * compatible binding, which has an extra "probe-type" property
+ * describing the type of flash probe necessary. */
+static struct mtd_info * __devinit obsolete_probe(struct of_device *dev,
+ struct map_info *map)
+{
+ struct device_node *dp = dev->node;
+ const char *of_probe;
+ struct mtd_info *mtd;
+ static const char *rom_probe_types[]
+ = { "cfi_probe", "jedec_probe", "map_rom"};
+ int i;
+
+ of_probe = of_get_property(dp, "probe-type", NULL);
+ if (!of_probe) {
+ for (i = 0; i < ARRAY_SIZE(rom_probe_types); i++) {
+ mtd = do_map_probe(rom_probe_types[i], map);
+ if (mtd)
+ return mtd;
+ }
+ return NULL;
+ } else if (strcmp(of_probe, "CFI") == 0) {
+ return do_map_probe("cfi_probe", map);
+ } else if (strcmp(of_probe, "JEDEC") == 0) {
+ return do_map_probe("jedec_probe", map);
+ } else {
+ if (strcmp(of_probe, "ROM") != 0)
+ dev_dbg(&dev->dev, "obsolete_probe: don't know probe type "
+ "'%s', mapping as rom\n", of_probe);
+ return do_map_probe("mtd_rom", map);
+ }
+}
+
static int __devinit of_physmap_probe(struct of_device *dev, const struct of_device_id *match)
{
struct device_node *dp = dev->node;
struct resource res;
struct physmap_flash_info *info;
- const char **probe_type;
- const char *of_probe;
+ const char *probe_type = (const char *)match->data;
const u32 *width;
int err;
@@ -174,21 +282,11 @@ static int __devinit of_physmap_probe(st
simple_map_init(&info->map);
- of_probe = of_get_property(dp, "probe-type", NULL);
- if (of_probe == NULL) {
- probe_type = rom_probe_types;
- for (; info->mtd == NULL && *probe_type != NULL; probe_type++)
- info->mtd = do_map_probe(*probe_type, &info->map);
- } else if (!strcmp(of_probe, "CFI"))
- info->mtd = do_map_probe("cfi_probe", &info->map);
- else if (!strcmp(of_probe, "JEDEC"))
- info->mtd = do_map_probe("jedec_probe", &info->map);
- else {
- if (strcmp(of_probe, "ROM"))
- dev_dbg(&dev->dev, "map_probe: don't know probe type "
- "'%s', mapping as rom\n", of_probe);
- info->mtd = do_map_probe("mtd_rom", &info->map);
- }
+ if (probe_type)
+ info->mtd = do_map_probe(probe_type, &info->map);
+ else
+ info->mtd = obsolete_probe(dev, &info->map);
+
if (info->mtd == NULL) {
dev_err(&dev->dev, "map_probe failed\n");
err = -ENXIO;
@@ -196,19 +294,7 @@ static int __devinit of_physmap_probe(st
}
info->mtd->owner = THIS_MODULE;
-#ifdef CONFIG_MTD_PARTITIONS
- err = parse_mtd_partitions(info->mtd, part_probe_types, &info->parts, 0);
- if (err > 0) {
- add_mtd_partitions(info->mtd, info->parts, err);
- } else if ((err = parse_flash_partitions(dp, &info->parts)) > 0) {
- dev_info(&dev->dev, "Using OF partition information\n");
- add_mtd_partitions(info->mtd, info->parts, err);
- info->nr_parts = err;
- } else
-#endif
-
- add_mtd_device(info->mtd);
- return 0;
+ return process_partitions(info, dev);
err_out:
of_physmap_remove(dev);
@@ -221,6 +307,14 @@ err_out:
static struct of_device_id of_physmap_match[] = {
{
+ .compatible = "cfi-flash",
+ .data = (void *)"cfi_probe",
+ },
+ {
+ .compatible = "jedec-flash",
+ .data = (void *)"jedec_probe",
+ },
+ {
.type = "rom",
.compatible = "direct-mapped"
},
Index: working-2.6/arch/powerpc/boot/dts/ebony.dts
===================================================================
--- working-2.6.orig/arch/powerpc/boot/dts/ebony.dts 2007-08-28 13:25:42.000000000 +1000
+++ working-2.6/arch/powerpc/boot/dts/ebony.dts 2007-08-28 13:41:00.000000000 +1000
@@ -142,13 +142,15 @@
interrupt-parent = <&UIC1>;
small-flash at 0,80000 {
- device_type = "rom";
- compatible = "direct-mapped";
- probe-type = "JEDEC";
+ compatible = "jedec-flash";
bank-width = <1>;
- partitions = <0 80000>;
- partition-names = "OpenBIOS";
reg = <0 80000 80000>;
+ #address-cells = <1>;
+ #size-cells = <1>;
+ OpenBIOS at 0 {
+ reg = <0 80000>;
+ read-only;
+ };
};
ds1743 at 1,0 {
@@ -158,14 +160,17 @@
};
large-flash at 2,0 {
- device_type = "rom";
- compatible = "direct-mapped";
- probe-type = "JEDEC";
+ compatible = "jedec-flash";
bank-width = <1>;
- partitions = <0 380000
- 380000 80000>;
- partition-names = "fs", "firmware";
reg = <2 0 400000>;
+ #address-cells = <1>;
+ #size-cells = <1>;
+ fs at 0 {
+ reg = <0 380000>;
+ };
+ firmware at 380000 {
+ reg = <380000 80000>;
+ };
};
ir at 3,0 {
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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