| Message ID | 1432226652-8947-1-git-send-email-srinivas.kandagatla@linaro.org |
|---|---|
| State | New |
| Headers | show |
On 16/06/15 23:53, Stephen Boyd wrote: > On 05/21/2015 09:44 AM, Srinivas Kandagatla wrote: >> diff --git a/Documentation/devicetree/bindings/nvmem/nvmem.txt b/Documentation/devicetree/bindings/nvmem/nvmem.txt >> new file mode 100644 >> index 0000000..ecea654 >> --- /dev/null >> +++ b/Documentation/devicetree/bindings/nvmem/nvmem.txt >> @@ -0,0 +1,84 @@ >> += NVMEM Data Device Tree Bindings = >> + >> +This binding is intended to represent the location of hardware >> +configuration data stored in NVMEMs. > > It would be worthwhile spelling out what NVMEM stands for. > >> + >> +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 >> +to this node. > > children of this node? > Yep, will fix the text >> + >> +Optional properties: >> + read-only: Mark the provider as read only. >> + >> += 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 bits of the data we care about. >> + There could be more then one offset-length pairs in this property. > > s/then/than/ Yep. > >> + >> +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. >> + > > Hopefully the consumer knows the endianness of the data stored. As we read byte-byte, does it matter, as long as consumer gets them in the same order as its stored. > >> +For example: >> + >> + /* Provider */ >> + qfprom: qfprom@00700000 { >> + ... >> + >> + /* Data cells */ >> + tsens_calibration: calib@404 { >> + reg = <0x404 0x10>; >> + }; >> + >> + tsens_calibration_bckp: calib_bckp@504 { >> + reg = <0x504 0x11>; >> + bit-offset = 6; >> + nbits = 128; >> + }; >> + >> + pvs_version: pvs-version@6 { >> + reg = <0x6 0x2> >> + bit-offset = 7; >> + nbits = 2; >> + }; >> + >> + speed_bin: speed-bin@c{ >> + reg = <0xc 0x1>; >> + bit-offset = 2; >> + nbits = 3; >> + >> + }; >> + ... >> + }; >> + >> += Data consumers = >> +Are device nodes which consume nvmem data cells/providers. >> + >> +Required-properties: >> +nvmem-cell: list of phandle to the nvmem data cells. >> +nvmem-cell-names: names for the each nvmem-cell specified >> + >> +Optional-properties: >> +nvmem : list of phandles to nvmem providers. >> +nvmem-names: names for the each nvmem provider. > > Is nvmem-names required if nvmem is used? Yes, will fix it. > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
On 19/06/15 11:36, maitysanchayan@gmail.com wrote: > Hello Srinivas, > > On 15-05-21 17:44:12, Srinivas Kandagatla wrote: >> 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 <maxime.ripard@free-electrons.com> >> [Maxime Ripard: intial version of eeprom framework] >> Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org> >> --- >> Documentation/devicetree/bindings/nvmem/nvmem.txt | 84 +++++++++++++++++++++++ >> 1 file changed, 84 insertions(+) >> create mode 100644 Documentation/devicetree/bindings/nvmem/nvmem.txt >> >> diff --git a/Documentation/devicetree/bindings/nvmem/nvmem.txt b/Documentation/devicetree/bindings/nvmem/nvmem.txt >> new file mode 100644 >> index 0000000..ecea654 >> --- /dev/null >> +++ b/Documentation/devicetree/bindings/nvmem/nvmem.txt >> @@ -0,0 +1,84 @@ >> += NVMEM Data Device Tree Bindings = >> + >> +This binding is intended to represent the location of hardware >> +configuration data stored in NVMEMs. >> + >> +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 >> +to this node. >> + >> +Optional properties: >> + read-only: Mark the provider as read only. >> + >> += 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 bits of the data we care about. >> + There could be more then 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. >> + >> +For example: >> + >> + /* Provider */ >> + qfprom: qfprom@00700000 { >> + ... >> + >> + /* Data cells */ >> + tsens_calibration: calib@404 { >> + reg = <0x404 0x10>; >> + }; >> + >> + tsens_calibration_bckp: calib_bckp@504 { >> + reg = <0x504 0x11>; >> + bit-offset = 6; >> + nbits = 128; >> + }; >> + >> + pvs_version: pvs-version@6 { >> + reg = <0x6 0x2> >> + bit-offset = 7; >> + nbits = 2; >> + }; >> + >> + speed_bin: speed-bin@c{ >> + reg = <0xc 0x1>; >> + bit-offset = 2; >> + nbits = 3; >> + >> + }; >> + ... >> + }; > > We have a need of exposing information like SoC ID, revision and such > which is what this nvmem framework proposes to be suitable for. Till > now I was trying a different approach for the same [1]. > > The On Chip One Time Programmable block on the Vybrid can be handled > nicely with this nvmem framework however I had a few queries with > regards to the framework after trying it on a Vybrid VF61 SoC. > > 1. From what I understand, getting the information in hex is the only > way possible as of now? Would it be possible to expose the information nvmem file in the /sys/ is just a binary file. hexdump is one of the ways to dump the data, the user can read the binary file and interpret the data in the way he wants it. > as strings from different paths under /sys/class/nvmem/*/nvmem/? > > For example, if I have a sub node as below > > ocotp: ocotp@400a5000 { > compatible = "fsl,vf610-ocotp"; > reg = <0x400a5000 0x1000>; > > ocotp_cfg0: cfg0@410 { > reg = <0x410 0x1>; > }; > > ocotp_cfg1: cfg1@420 { > reg = <0x420 0x1>; > }; > }; > > The values from the above register locations represented by the two > sub nodes above can perhaps be exposed as strings? Even if they are > not exposed as strings, making them available in separate paths, is > that something which can be done? So depending on the sub node as > above, /sys/class/nvmem/ocotp0/nvmem/cfg0/ would give values from > the registers specified. I was thinking of add similar support to show cells in /sys/class/nvmem/*/cells/cfg0 in future once the framework is merged. For now I want to keep it simple. This would be binary content again. you can dump it using strings any program which wants to interpret it differently. > > Basically the output of /sys/class/nvmem/*/nvmem being restricted > to only the subnodes specified is what I was hoping to get along > with separate paths. > > 2. What if the required information is scattered across different memory > regions? In my case, the SoC ID is available from one OCOTP peripheral > block, the revision is in a separate ROM area at the start of the memory > map and some CPU information I am interested in is in another memory > region. I am not sure what would be the right way to approach it with > the nvmem framework. I think you would have two providers in that case one is ocotp and other is ROM. DT would look something like this: /* Provider */ ocotp { ... soc-id { reg = ...; }; }; rom { ... soc-reg { reg = ...; }; }; /* consumer */ consumer { nvmem-cell = <&soc_id>, <&soc_rev>; nvmem-cell-names = "soc-id", "soc-revision"; }; --srini > > [1] https://lkml.org/lkml/2015/6/5/189 > > Thanks & Regards, > Sanchayan Maity. > > <snip> > -- To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in
diff --git a/Documentation/devicetree/bindings/nvmem/nvmem.txt b/Documentation/devicetree/bindings/nvmem/nvmem.txt new file mode 100644 index 0000000..ecea654 --- /dev/null +++ b/Documentation/devicetree/bindings/nvmem/nvmem.txt @@ -0,0 +1,84 @@ += NVMEM Data Device Tree Bindings = + +This binding is intended to represent the location of hardware +configuration data stored in NVMEMs. + +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 +to this node. + +Optional properties: + read-only: Mark the provider as read only. + += 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 bits of the data we care about. + There could be more then 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. + +For example: + + /* Provider */ + qfprom: qfprom@00700000 { + ... + + /* Data cells */ + tsens_calibration: calib@404 { + reg = <0x404 0x10>; + }; + + tsens_calibration_bckp: calib_bckp@504 { + reg = <0x504 0x11>; + bit-offset = 6; + nbits = 128; + }; + + pvs_version: pvs-version@6 { + reg = <0x6 0x2> + bit-offset = 7; + nbits = 2; + }; + + speed_bin: speed-bin@c{ + reg = <0xc 0x1>; + bit-offset = 2; + nbits = 3; + + }; + ... + }; + += Data consumers = +Are device nodes which consume nvmem data cells/providers. + +Required-properties: +nvmem-cell: list of phandle to the nvmem data cells. +nvmem-cell-names: names for the each nvmem-cell specified + +Optional-properties: +nvmem : list of phandles to nvmem providers. +nvmem-names: names for the each nvmem provider. + +For example: + + tsens { + ... + nvmem-cell = <&tsens_calibration>; + nvmem-cell-names = "calibration"; + };