Re: [PATCH v2 4/8] dt-bindings: power: reset: add bindings for NVMEM hardware storing PSCR Data
From: Oleksij Rempel <o.rempel@pengutronix.de>
Date: 2024-01-26 16:52:10
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linux-pm, lkml
On Fri, Jan 26, 2024 at 10:03:51AM +0100, Krzysztof Kozlowski wrote:
On 25/01/2024 18:11, Oleksij Rempel wrote:quoted
On Thu, Jan 25, 2024 at 11:57:18AM +0100, Krzysztof Kozlowski wrote:quoted
On 24/01/2024 13:22, Oleksij Rempel wrote:quoted
Add device tree bindings that describe hardware implementations of Non-Volatile Memory (NVMEM) used for storing Power State Change Reasons (PSCR). + that stores Power State Change Reasons (PSCR). + +allOf: + - $ref: pscrr.yaml# + +properties: + compatible: + const: pscrr-nvmem +So that's a driver :/. Maybe Rob will like it, but it's a no from me. Please come up with something really suiting DEVICES, not DRIVERS.If I understand your distinction between 'DEVICES' and 'DRIVERS' correctly, 'DEVICES' in the device tree context are meant to represent physical hardware components, while 'DRIVERS' refer to softwareYes.quoted
abstractions of these components. However, there are numerous device tree instances, like software-based implementations for SPI, I2C, or GPIO, which could also be interpreted as 'DRIVERS' in the context ofTrue. Yet they are still for physical interfaces. There is no DTS having some virtual I2C for a board which does not have I2C.quoted
your email. Similarly, the binding for PSCRR represents functionality not fully implemented in hardware but supported by the hardware component of NVMEM, akin to how ramoops or other functionalities are represented.You don't need a binding for your case. Instantiate it whatever you wish - modprobe for example - and configure through approved kernel interfaces - sysfs for example.
About using sysfs for the NVMEM cell, it won't work for my needs because I have to know about reboot events before the filesystem is ready. So, I'm thinking of using a boot parameter for the kernel. It would look like this: pscrr-nvmem.nvmem_cell_alias=nvmem-cell0. This way, I can set up the NVMEM cell right at the system's start. I'll need to use stable NVMEM cell names for this. Is it ok to introduce NVMEM cell aliases in the devicetree? Best Regards, Oleksij -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |