Re: [PATCH v2 1/3] nvmem: core: introduce cells parser

From: Srinivas Kandagatla
Date: Mon Jun 21 2021 - 07:00:16 EST

On 16/06/2021 13:33, Vadym Kochan wrote:
diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
index bca671ff4e54..648373ced6d4 100644
--- a/drivers/nvmem/core.c
+++ b/drivers/nvmem/core.c
@@ -39,6 +39,7 @@ struct nvmem_device {
nvmem_reg_read_t reg_read;
nvmem_reg_write_t reg_write;
struct gpio_desc *wp_gpio;
+ struct nvmem_parser_data *parser_data;
This should be renamed to nvmem_cell_info_parser or something on those lines
to avoid any misunderstanding on what exactly this parser is about.

May be can totally avoid this by using parser name only during register.

I added this to keep parsed cells particulary for this nvmem in case
same parser is used for several nvmem's and mostly because of using also
cell lookup info. I will try to also answer your below question why do I need
lookups ?

I use of_get_mac_address() func to fetch mac-address from nvmem cell.
Eventually this func calls of_get_mac_addr_nvmem() which (as I understand it
correctly) can find cells via DT by parsing "nvmem-cell-names" or via cell lookup
info of platform_device. I use the 2nd option with the following sample

## DT ##
eeprom_at24: at24@56 {
compatible = "atmel,24c32";
nvmem-cell-parser-name = "onie-tlv-cells";
reg = <0x56>;

onie_tlv_parser: onie-tlv-cells {
compatible = "nvmem-cell-parser";
status = "okay";

---> add ability here to map cell con_id to cell_name ?


some_dev_node {
compatible = "xxx";
base-mac-provider = <&onie_tlv_parser>;

Real nvmem provider is eeprom_at24, why do you use onie_tlv_parse as your mac provider?
If you use eeprom_at24 then of_get_mac_address() should get mac-address directly from cell info.

status = "okay";

== CODE ==
base_mac_np = of_parse_phandle(np, "base-mac-provider", 0);
ret = of_get_mac_address(base_mac_np, base_mac);

And it works with this implementation because onie-tlv-cells is
registered as platform_device which name is the same as parser's name.
So the really tricky part for me is to make this cells lookup work.

cell lookups are more of intended for board files, adding them in this case is really not correct. The whole purpose of this driver is to parse the tlv cell infos into nvmem cell info.


Of course would be great if you can point a way/idea to get rid the need of