[PATCH v6] mtd: support BB SRAM on ICP DAS LP-8x4x

[Rob Herring]

On Tue, Feb 23, 2016 at 09:58:01PM +0300, Sergei Ianovich wrote:
> This provides an MTD device driver for 512kB of battery backed up SRAM
> on ICPDAS LP-8X4X programmable automation controllers.
> 
> SRAM chip is connected via FPGA and is not accessible without a driver,
> unlike flash memory which is wired to CPU MMU.
> 
> This SRAM becomes an excellent persisent storage of volatile process
> data like counter values and sensor statuses. Storing those data in
> flash or mmc card is not a viable solution.
> 
> Signed-off-by: Sergei Ianovich <ynvich at gmail.com>
> Reviewed-by: Brian Norris <computersforpeace at gmail.com>
> CC: Rob Herring <robh at kernel.org>
> 
>    v5..v6
>    * replace wildcards in compatible and module name
>    * drop obsolete mtd_part_parser_data.of_node
> 
>    v4..v5
>    * remove .owner from struct platform_driver
>    * constify struct of_device_id
>     for further Brian Norris comments:
>    * drop unused property from doc file
>    * move defconfig update to a different file
>    * drop extra match w/ of_match_device()
> 
>    v3..v4 for Brian Norris 'Reviewed-by'
>    * add doc file for DT binding
>    * move DTS binding to a different patch (8/21)
>    * drop unused include directive
>    * drop safely unused callback
>    * drop non-default partion probe types
>    * drop duplicate error checks
>    * drop duplicate error reporting
>    * fixed error message on MTD registeration
>    * fixed module removal routine
> 
>    v2..v3
>    * no changes (except number 08/16 -> 10/21)
> 
>    v0..v2
>    * use device tree
>    * use devm helpers where possible
> ---
>  .../devicetree/bindings/mtd/icpdas-lp8841-sram.txt |  23 +++

Acked-by: Rob Herring <robh at kernel.org>

>  drivers/mtd/devices/Kconfig                        |  14 ++
>  drivers/mtd/devices/Makefile                       |   1 +
>  drivers/mtd/devices/sram_lp8841.c                  | 198 +++++++++++++++++++++
>  4 files changed, 236 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/mtd/icpdas-lp8841-sram.txt
>  create mode 100644 drivers/mtd/devices/sram_lp8841.c