linux-kernel - Re: [PATCH v1 1/1] mtd: devices: add ACPI support for non-jedec m25p80

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Date:   Thu, 07 Mar 2019 17:40:16 +0000
From:   David Woodhouse <dwmw2@...radead.org>
To:     Flavio Suligoi <f.suligoi@...m.it>,
        Brian Norris <computersforpeace@...il.com>,
        Boris Brezillon <bbrezillon@...nel.org>,
        Marek Vasut <marek.vasut@...il.com>,
        Richard Weinberger <richard@....at>,
        Mark Brown <broonie@...nel.org>,
        Frieder Schrempf <frieder.schrempf@...eet.de>,
        Yogesh Gaur <yogeshnarayan.gaur@....com>,
        linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 1/1] mtd: devices: add ACPI support for non-jedec
 m25p80

On Tue, 2019-02-26 at 11:48 +0100, Flavio Suligoi wrote:
> For the x86 machines a m25p80-compatible device have to be declared using
> an ACPI table (which can be directly a part of the BIOS ACPI tables).
> 
> In this case it is necessary to add the device in the "of_device_id" structure
> list, to permit the device name matching by the ACPI kernel functions.
> 
> This is an example of a SSDT table for the Everspin mr25h40:
> 
> DefinitionBlock ("mr25h40.aml", "SSDT", 5, "ASEMsp", "MR25H40", 1)
> {
> 	External (_SB.SPI1, DeviceObj)
> 
> 	Scope (\_SB.SPI1)
> 	{
> 		Device (NVR0)
> 		{
> 			Name (_HID, "PRP0001")
> 			Name (_DDN, "Everspin MR25H40 MRAM")
> 			Name (_CRS, ResourceTemplate () {
> 				SpiSerialBus (
> 				1,                      // Chip select
> 				PolarityLow,            // Chip select is active low
> 				FourWireMode,           // Full duplex
> 				8,                      // Bits per word is 8 (byte)
> 				ControllerInitiated,    // Don't care
> 				10000000,               // 10 MHz
> 				ClockPolarityLow,       // SPI mode 0 ClockPolarityLow
> 				ClockPhaseFirst,        // SPI mode 0 ClockPhaseFirst
> 				"\\_SB.SPI1",      	// SPI host controller
> 				0,			// Must be 0
> 				ResourceConsumer,
> 				,
> 				)
> 			})
> 
> 			Name (_DSD, Package () {
> 				ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
> 				Package () {
> 					Package () {"compatible", "mr25h40"},
> 				}
> 			})
> 		}
> 	}
> }
> 
> Signed-off-by: Flavio Suligoi <f.suligoi@...m.it>

Why use the specific chip name in the "compatible" property? Why isn't
it using "jedec,spi-nor"? 

Does this still actually get passed through to spi_nor_scan()... and is
it *necessary*? Can't the chips be probed?

> ---
> 
> v1: - first patch version
> 
>  drivers/mtd/devices/m25p80.c | 57 +++++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 56 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/mtd/devices/m25p80.c b/drivers/mtd/devices/m25p80.c
> index c4a1d04..b5c7db8 100644
> --- a/drivers/mtd/devices/m25p80.c
> +++ b/drivers/mtd/devices/m25p80.c
> @@ -312,9 +312,64 @@ MODULE_DEVICE_TABLE(spi, m25p_ids);
>  static const struct of_device_id m25p_of_table[] = {
>  	/*
>  	 * Generic compatibility for SPI NOR that can be identified by the
> -	 * JEDEC READ ID opcode (0x9F). Use this, if possible.
> +	 * JEDEC READ ID opcode (0x9F). Use this (jedec,spi-nor), if possible.
> +	 *
> +	 * The list of all flash devices is instead necessary in x86 machines,
> +	 * to use a "non-jedec device" inside the ACPI BIOS tables.
>  	 */
>  	{ .compatible = "jedec,spi-nor" },
> +	{ .compatible = "s25sl064a" },
> +	{ .compatible = "w25x16" },
> +	{ .compatible = "m25p10" },
> +	{ .compatible = "m25px64" },
> +	{ .compatible = "at25df321a" },
> +	{ .compatible = "at25df641" },
> +	{ .compatible = "at26df081a" },
> +	{ .compatible = "mx25l4005a" },
> +	{ .compatible = "mx25l1606e" },
> +	{ .compatible = "mx25l6405d" },
> +	{ .compatible = "mx25l12805d" },
> +	{ .compatible = "mx25l25635e" },
> +	{ .compatible = "mx66l51235l" },
> +	{ .compatible = "n25q064" },
> +	{ .compatible = "n25q128a11" },
> +	{ .compatible = "n25q128a13" },
> +	{ .compatible = "n25q512a" },
> +	{ .compatible = "s25fl256s1" },
> +	{ .compatible = "s25fl512s" },
> +	{ .compatible = "s25sl12801" },
> +	{ .compatible = "s25fl008k" },
> +	{ .compatible = "s25fl064k" },
> +	{ .compatible = "sst25vf040b" },
> +	{ .compatible = "sst25vf016b" },
> +	{ .compatible = "sst25vf032b" },
> +	{ .compatible = "sst25wf040" },
> +	{ .compatible = "m25p40" },
> +	{ .compatible = "m25p80" },
> +	{ .compatible = "m25p16" },
> +	{ .compatible = "m25p32" },
> +	{ .compatible = "m25p64" },
> +	{ .compatible = "m25p128" },
> +	{ .compatible = "w25x80" },
> +	{ .compatible = "w25x32" },
> +	{ .compatible = "w25q32" },
> +	{ .compatible = "w25q32dw" },
> +	{ .compatible = "w25q80bl" },
> +	{ .compatible = "w25q128" },
> +	{ .compatible = "w25q256" },
> +	{ .compatible = "m25p05-nonjedec" },
> +	{ .compatible = "m25p10-nonjedec" },
> +	{ .compatible = "m25p20-nonjedec" },
> +	{ .compatible = "m25p40-nonjedec" },
> +	{ .compatible = "m25p80-nonjedec" },
> +	{ .compatible = "m25p16-nonjedec" },
> +	{ .compatible = "m25p32-nonjedec" },
> +	{ .compatible = "m25p64-nonjedec" },
> +	{ .compatible = "m25p128-nonjedec" },
> +	{ .compatible = "mr25h128" },
> +	{ .compatible = "mr25h256" },
> +	{ .compatible = "mr25h10" },
> +	{ .compatible = "mr25h40" },
>  	{}
>  };
>  MODULE_DEVICE_TABLE(of, m25p_of_table);
> -- 
> 2.7.4
> 
> 
> ______________________________________________________
> Linux MTD discussion mailing list
> http://lists.infradead.org/mailman/listinfo/linux-mtd/

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