[PATCH v7 4/9] nvmem: Add bindings for simple nvmem framework
From: Rob Herring <hidden>
Date: 2015-07-10 19:04:52
Also in:
linux-api, linux-arm-msm, linux-devicetree, lkml
On Fri, Jul 10, 2015 at 4:45 AM, Srinivas Kandagatla [off-list ref] wrote:
quoted hunk ↗ jump to hunk
This patch adds bindings for simple nvmem framework which allows nvmem consumers to talk to nvmem providers to get access to nvmem cell data. Signed-off-by: Maxime Ripard <redacted> [Maxime Ripard: intial version of eeprom framework] Signed-off-by: Srinivas Kandagatla <redacted> --- Documentation/devicetree/bindings/nvmem/nvmem.txt | 85 +++++++++++++++++++++++ 1 file changed, 85 insertions(+) create mode 100644 Documentation/devicetree/bindings/nvmem/nvmem.txtdiff --git a/Documentation/devicetree/bindings/nvmem/nvmem.txt b/Documentation/devicetree/bindings/nvmem/nvmem.txt new file mode 100644 index 0000000..849f1e1 --- /dev/null +++ b/Documentation/devicetree/bindings/nvmem/nvmem.txt@@ -0,0 +1,85 @@ += NVMEM(Non Volatile Memory) Data Device Tree Bindings = + +This binding is intended to represent the location of hardware +configuration data stored in NVMEMs like eeprom, efuses and so on. + +On a significant proportion of boards, the manufacturer has stored +some data on NVMEM, for the OS to be able to retrieve these information +and act upon it. Obviously, the OS has to know about where to retrieve +these data from, and where they are stored on the storage device. + +This document is here to document this. + += Data providers = +Contains bindings specific to provider drivers and data cells as children +of this node.
#address-cells and #size-cells are required here.
+ +Optional properties: + read-only: Mark the provider as read only.
Couldn't this be per field rather than global?
+ += Data cells = +These are the child nodes of the provider which contain data cell +information like offset and size in nvmem provider. + +Required properties: +reg: specifies the offset in byte within that storage device, start bit + in the byte and the length in bytes of the data we care about. + There could be more than one offset-length pairs in this property. + +Optional properties: + +bit-offset: specifies the offset in bit within the address range specified + by reg property. Can take values from 0-7. +nbits: specifies number of bits this cell occupies starting from bit-offset.
How about just: "bits = <<offset> <size>>" Then the bit specification is more aligned with the byte location (i.e. reg property). You could also do this all in the reg property with 2 address cells for byte and bit position and then size can be in bits. reg doesn't have to match a memory mapped bus addressing meanings. If you wanted to handle ranges and address translation, then you would need custom functions like PCI does. I'm not sure you would need that.
+
+For example:
+
+ /* Provider */
+ qfprom: qfprom at 00700000 {
+ ...
+
+ /* Data cells */
+ tsens_calibration: calib at 404 {
+ reg = <0x404 0x10>;
+ };
+
+ tsens_calibration_bckp: calib_bckp at 504 {
+ reg = <0x504 0x11>;
+ bit-offset = 6;
+ nbits = 128;
+ };
+
+ pvs_version: pvs-version at 6 {
+ reg = <0x6 0x2>
+ bit-offset = 7;
+ nbits = 2;
+ };
+
+ speed_bin: speed-bin at c{
+ reg = <0xc 0x1>;
+ bit-offset = 2;
+ nbits = 3;
+
+ };
+ ...
+ };
+
+= Data consumers =
+Are device nodes which consume nvmem data cells/providers.
+
+Required-properties:
+nvmem-cells: list of phandle to the nvmem data cells.
+nvmem-cell-names: names for the each nvmem-cells specified. Required if
+ nvmem-cells is used.
+
+Optional-properties:
+nvmem : list of phandles to nvmem providers.
+nvmem-names: names for the each nvmem provider. required if nvmem is used.
+
+For example:
+
+ tsens {
+ ...
+ nvmem-cells = <&tsens_calibration>;
+ nvmem-cell-names = "calibration";
+ };
--
1.9.1