Message ID | 20210322181949.2805-1-michael@walle.cc |
---|---|
Headers | show |
Series | mtd: core: OTP nvmem provider support | expand |
Hi Michael, On 22/03/2021 18:19, Michael Walle wrote: > The goal is to fetch a (base) MAC address from the OTP region of a SPI NOR > flash. > > This is the first part, where I try to add the nvmem provider support to > the MTD core. > > I'm not sure about the device tree bindings. Consider the following two > variants: > > (1) > flash@0 { > .. > > otp { > compatible = "mtd-user-otp"; > #address-cells = <1>; > #size-cells = <1>; > > serial-number@0 { > reg = <0x0 0x8>; > }; > }; > }; > > (2) > flash@0 { > .. > > otp { > compatible = "mtd-user-otp"; > #address-cells = <1>; > #size-cells = <1>; > > some-useful-name { > compatible = "nvmem-cells"; > > serial-number@0 { > reg = <0x0 0x8>; > }; > }; > }; > }; > > Both bindings use a subnode "opt[-N]". We cannot have the nvmem cells as > children to the flash node because of the legacy partition binding. > > (1) seems to be the form which is used almost everywhere in the kernel. > That is, the nvmem cells are just children of the parent node. > > (2) seem to be more natural, because there might also be other properties > inside the otp subnode and might be more future-proof. > > At the moment this patch implements (1). > Have you looked at this series[1], are you both trying to do the same thing? [1] https://lore.kernel.org/linux-mtd/20210312062830.20548-2-ansuelsmth@gmail.com/T/ --srini > Michael Walle (4): > nvmem: core: allow specifying of_node > dt-bindings: mtd: add YAML schema for the generic MTD bindings > dt-bindings: mtd: add OTP bindings > mtd: core: add OTP nvmem provider support > > .../devicetree/bindings/mtd/common.txt | 16 +- > .../devicetree/bindings/mtd/mtd.yaml | 110 +++++++++++++ > drivers/mtd/mtdcore.c | 149 ++++++++++++++++++ > drivers/nvmem/core.c | 4 +- > include/linux/mtd/mtd.h | 2 + > include/linux/nvmem-provider.h | 2 + > 6 files changed, 267 insertions(+), 16 deletions(-) > create mode 100644 Documentation/devicetree/bindings/mtd/mtd.yaml >
Hi Srinivas, Am 2021-03-30 11:42, schrieb Srinivas Kandagatla: > On 22/03/2021 18:19, Michael Walle wrote: >> The goal is to fetch a (base) MAC address from the OTP region of a SPI >> NOR >> flash. >> >> This is the first part, where I try to add the nvmem provider support >> to >> the MTD core. >> >> I'm not sure about the device tree bindings. Consider the following >> two >> variants: >> >> (1) >> flash@0 { >> .. >> >> otp { >> compatible = "mtd-user-otp"; >> #address-cells = <1>; >> #size-cells = <1>; >> >> serial-number@0 { >> reg = <0x0 0x8>; >> }; >> }; >> }; >> >> (2) >> flash@0 { >> .. >> >> otp { >> compatible = "mtd-user-otp"; >> #address-cells = <1>; >> #size-cells = <1>; >> >> some-useful-name { >> compatible = "nvmem-cells"; >> >> serial-number@0 { >> reg = <0x0 0x8>; >> }; >> }; >> }; >> }; >> >> Both bindings use a subnode "opt[-N]". We cannot have the nvmem cells >> as >> children to the flash node because of the legacy partition binding. >> >> (1) seems to be the form which is used almost everywhere in the >> kernel. >> That is, the nvmem cells are just children of the parent node. >> >> (2) seem to be more natural, because there might also be other >> properties >> inside the otp subnode and might be more future-proof. >> >> At the moment this patch implements (1). >> > > > Have you looked at this series[1], are you both trying to do the same > thing? Yes, I've seen these, but they are for MTD partitions. OTP regions are not MTD partitions (and cannot be mapped to them). -michael > > [1] > https://lore.kernel.org/linux-mtd/20210312062830.20548-2-ansuelsmth@gmail.com/T/ > > --srini > > >> Michael Walle (4): >> nvmem: core: allow specifying of_node >> dt-bindings: mtd: add YAML schema for the generic MTD bindings >> dt-bindings: mtd: add OTP bindings >> mtd: core: add OTP nvmem provider support >> >> .../devicetree/bindings/mtd/common.txt | 16 +- >> .../devicetree/bindings/mtd/mtd.yaml | 110 +++++++++++++ >> drivers/mtd/mtdcore.c | 149 >> ++++++++++++++++++ >> drivers/nvmem/core.c | 4 +- >> include/linux/mtd/mtd.h | 2 + >> include/linux/nvmem-provider.h | 2 + >> 6 files changed, 267 insertions(+), 16 deletions(-) >> create mode 100644 Documentation/devicetree/bindings/mtd/mtd.yaml >>
On 22/03/2021 18:19, Michael Walle wrote: > Until now, the of_node of the parent device is used. Some devices > provide more than just the nvmem provider. To avoid name space clashes, > add a way to allow specifying the nvmem cells in subnodes. Consider the > following example: > > flash@0 { > compatible = "jedec,spi-nor"; > > partitions { > compatible = "fixed-partitions"; > #address-cells = <1>; > #size-cells = <1>; > > partition@0 { > reg = <0x000000 0x010000>; > }; > }; > > otp { > compatible = "mtd-user-otp"; I would have expected this to come up as a proper device, but am not 100% sure how MTD handles flashes and its partitions. > #address-cells = <1>; > #size-cells = <1>; > > serial-number@0 { > reg = <0x0 0x8>; > }; > }; > }; > > There the nvmem provider might be the MTD partition or the OTP region of > the flash. > > Add a new config->of_node parameter, which if set, will be used instead > of the parent's of_node. > > Signed-off-by: Michael Walle <michael@walle.cc> > --- Patch is fine as it its. If you plan to take this via mtd tree here is my Ack Acked-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org> --srini > drivers/nvmem/core.c | 4 +++- > include/linux/nvmem-provider.h | 2 ++ > 2 files changed, 5 insertions(+), 1 deletion(-) > > diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c > index bca671ff4e54..62d363a399d3 100644 > --- a/drivers/nvmem/core.c > +++ b/drivers/nvmem/core.c > @@ -789,7 +789,9 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config) > nvmem->reg_write = config->reg_write; > nvmem->keepout = config->keepout; > nvmem->nkeepout = config->nkeepout; > - if (!config->no_of_node) > + if (config->of_node) > + nvmem->dev.of_node = config->of_node; > + else if (!config->no_of_node) > nvmem->dev.of_node = config->dev->of_node; > > switch (config->id) { > diff --git a/include/linux/nvmem-provider.h b/include/linux/nvmem-provider.h > index e162b757b6d5..471cb7b9e896 100644 > --- a/include/linux/nvmem-provider.h > +++ b/include/linux/nvmem-provider.h > @@ -57,6 +57,7 @@ struct nvmem_keepout { > * @type: Type of the nvmem storage > * @read_only: Device is read-only. > * @root_only: Device is accessibly to root only. > + * @of_node: If given, this will be used instead of the parent's of_node. > * @no_of_node: Device should not use the parent's of_node even if it's !NULL. > * @reg_read: Callback to read data. > * @reg_write: Callback to write data. > @@ -86,6 +87,7 @@ struct nvmem_config { > enum nvmem_type type; > bool read_only; > bool root_only; > + struct device_node *of_node; > bool no_of_node; > nvmem_reg_read_t reg_read; > nvmem_reg_write_t reg_write; >