mtd: maps: add mtd-ram support to physmap_of

Use physmap_of to access RAMs as mtd and add documenation for it. This approach
is a lot less intrusive as adding an of-wrapper around plat-ram.c. As most
extensions of plat-ram.c (e.g. custom map-functions) can't be mapped to the
device tree anyhow, extending physmap_of seems to be the cleanest approach.

Tested with a phyCORE-MPC5121e.

Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
Cc: Vitaly Wool <vwool@ru.mvista.com>
Cc: Artem Bityutskiy <dedekind@infradead.org>
Cc: Ken MacLeod <ken@bitsko.slc.ut.us>
Cc: Albrecht Dreß <albrecht.dress@arcor.de>
Acked-by: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

diff --git a/Documentation/powerpc/dts-bindings/mtd-physmap.txt b/Documentation/powerpc/dts-bindings/mtd-physmap.txt
index 667c9bde8699a3eb8433a223579529d443378aaa..80152cb567d91941f9b91e79cb456dc6a16a9833 100644 (file)
--- a/Documentation/powerpc/dts-bindings/mtd-physmap.txt
+++ b/Documentation/powerpc/dts-bindings/mtd-physmap.txt
@@ -1,18 +1,19 @@
-CFI or JEDEC memory-mapped NOR flash
+CFI or JEDEC memory-mapped NOR flash, MTD-RAM (NVRAM...)

 
 Flash chips (Memory Technology Devices) are often used for solid state
 file systems on embedded devices.
 
 
 Flash chips (Memory Technology Devices) are often used for solid state
 file systems on embedded devices.
 

- - compatible : should contain the specific model of flash chip(s)
-   used, if known, followed by either "cfi-flash" or "jedec-flash"
- - reg : Address range(s) of the flash chip(s)
+ - compatible : should contain the specific model of mtd chip(s)
+   used, if known, followed by either "cfi-flash", "jedec-flash"
+   or "mtd-ram".
+ - reg : Address range(s) of the mtd chip(s)

    It's possible to (optionally) define multiple "reg" tuples so that
    It's possible to (optionally) define multiple "reg" tuples so that

-   non-identical NOR chips can be described in one flash node.
- - bank-width : Width (in bytes) of the flash bank.  Equal to the
+   non-identical chips can be described in one node.
+ - bank-width : Width (in bytes) of the bank.  Equal to the

    device width times the number of interleaved chips.
    device width times the number of interleaved chips.

- - device-width : (optional) Width of a single flash chip.  If
+ - device-width : (optional) Width of a single mtd chip.  If

    omitted, assumed to be equal to 'bank-width'.
    omitted, assumed to be equal to 'bank-width'.

- - #address-cells, #size-cells : Must be present if the flash has
+ - #address-cells, #size-cells : Must be present if the device has

    sub-nodes representing partitions (see below).  In this case
    both #address-cells and #size-cells must be equal to 1.
 
    sub-nodes representing partitions (see below).  In this case
    both #address-cells and #size-cells must be equal to 1.
 


@@ -22,24 +23,24 @@ are defined:
  - vendor-id : Contains the flash chip's vendor id (1 byte).
  - device-id : Contains the flash chip's device id (1 byte).
 
  - 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
+In addition to the information on the mtd bank itself, the

 device tree may optionally contain additional information
 device tree may optionally contain additional information

-describing partitions of the flash address space.  This can be
+describing partitions of the address space.  This can be

 used on platforms which have strong conventions about which
 used on platforms which have strong conventions about which

-portions of the flash are used for what purposes, but which don't
+portions of a flash are used for what purposes, but which don't

 use an on-flash partition table such as RedBoot.
 
 use an on-flash partition table such as RedBoot.
 

-Each partition is represented as a sub-node of the flash device.
+Each partition is represented as a sub-node of the mtd device.

 Each node's name represents the name of the corresponding
 Each node's name represents the name of the corresponding

-partition of the flash device.
+partition of the mtd device.

 
 Flash partitions
 
 Flash partitions

- - reg : The partition's offset and size within the flash bank.
- - label : (optional) The label / name for this flash partition.
+ - reg : The partition's offset and size within the mtd bank.
+ - label : (optional) The label / name for this partition.

    If omitted, the label is taken from the node name (excluding
    the unit address).
  - read-only : (optional) This parameter, if present, is a hint to
    If omitted, the label is taken from the node name (excluding
    the unit address).
  - read-only : (optional) This parameter, if present, is a hint to

-   Linux that this flash partition should only be mounted
+   Linux that this 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.
    read-only.  This is usually used for flash partitions
    containing early-boot firmware images or data which should not
    be clobbered.


@@ -78,3 +79,12 @@ Here an example with multiple "reg" tuples:
                        reg = <0 0x04000000>;
                };
        };
                        reg = <0 0x04000000>;
                };
        };

+
+An example using SRAM:
+
+       sram@2,0 {
+               compatible = "samsung,k6f1616u6a", "mtd-ram";
+               reg = <2 0 0x00200000>;
+               bank-width = <2>;
+       };
+

diff --git a/drivers/mtd/maps/physmap_of.c b/drivers/mtd/maps/physmap_of.c
index e828d58910f0141738f2044d88b0fcd4018ac193..61e4eb48bb2d5a37dfad765e3399e3b22d6270f9 100644 (file)
--- a/drivers/mtd/maps/physmap_of.c
+++ b/drivers/mtd/maps/physmap_of.c
@@ -361,6 +361,10 @@ static struct of_device_id of_flash_match[] = {
                .compatible     = "jedec-flash",
                .data           = (void *)"jedec_probe",
        },
                .compatible     = "jedec-flash",
                .data           = (void *)"jedec_probe",
        },

+       {
+               .compatible     = "mtd-ram",
+               .data           = (void *)"map_ram",
+       },

        {
                .type           = "rom",
                .compatible     = "direct-mapped"
        {
                .type           = "rom",
                .compatible     = "direct-mapped"