linux-kernel - Re: [PATCH stblinux.git 2/2] firmware: bcm47xx_nvram: support platform device "brcm,nvram"

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Message-ID: <8e17b978-a527-97df-3f31-1fb2123a23e9@gmail.com>
Date:   Tue, 2 Mar 2021 08:59:52 -0800
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Rafał Miłecki <zajec5@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Nicolas Saenz Julienne <nsaenzjulienne@...e.de>
Cc:     Vivek Unune <npcomplete13@...il.com>,
        linux-arm-kernel@...ts.infradead.org, linux-mips@...r.kernel.org,
        devicetree@...r.kernel.org, bcm-kernel-feedback-list@...adcom.com,
        linux-kernel@...r.kernel.org,
        Rafał Miłecki <rafal@...ecki.pl>
Subject: Re: [PATCH stblinux.git 2/2] firmware: bcm47xx_nvram: support
 platform device "brcm,nvram"

On 3/1/21 11:44 PM, Rafał Miłecki wrote:
> From: Rafał Miłecki <rafal@...ecki.pl>
> 
> Add support for platform device providing mapping resource. This allows
> reading NVRAM based on DT mapping binding. It's required for devices
> that boot depending on NVRAM stored setup and provides early access to
> NVRAM data.
> 
> Signed-off-by: Rafał Miłecki <rafal@...ecki.pl>
> ---
> bcm47xx_nvram driver was originally added through MIPS tree, but this
> change doesn't affect BCM47XX (MIPS) as it doesn't use DT. It targets
> ARCH_BCM_5301X so I suggest this goes through the stblinux.git tree.

Can you see if this change can be replaced by the nvmem-rmem work that
Nicolas recently did to support something similar for the Raspberry Pi 4:

https://lkml.org/lkml/2021/1/29/235

> ---
>  drivers/firmware/broadcom/bcm47xx_nvram.c | 55 +++++++++++++++++++++++
>  1 file changed, 55 insertions(+)
> 
> diff --git a/drivers/firmware/broadcom/bcm47xx_nvram.c b/drivers/firmware/broadcom/bcm47xx_nvram.c
> index 835ece9c00f1..d5d19dd1b9e1 100644
> --- a/drivers/firmware/broadcom/bcm47xx_nvram.c
> +++ b/drivers/firmware/broadcom/bcm47xx_nvram.c
> @@ -13,6 +13,7 @@
>  #include <linux/kernel.h>
>  #include <linux/string.h>
>  #include <linux/mtd/mtd.h>
> +#include <linux/platform_device.h>
>  #include <linux/bcm47xx_nvram.h>
>  
>  #define NVRAM_MAGIC			0x48534C46	/* 'FLSH' */
> @@ -162,6 +163,60 @@ static int nvram_init(void)
>  	return -ENXIO;
>  }
>  
> +static int brcm_nvram_probe(struct platform_device *pdev)
> +{
> +	struct nvram_header __iomem *header;
> +	struct device *dev = &pdev->dev;
> +	struct resource *res;
> +	void __iomem *mmio;
> +	size_t copy_len;
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	if (!res) {
> +		dev_err(dev, "Failed to get resource\n");
> +		return -ENODEV;
> +	}
> +
> +	mmio = ioremap(res->start, resource_size(res));
> +	if (!mmio)
> +		return -ENOMEM;
> +
> +	header = (struct nvram_header *)mmio;
> +	copy_len = DIV_ROUND_UP(sizeof(*header) + header->len, 4);
> +	if (header->magic != NVRAM_MAGIC) {
> +		dev_err(dev, "No NVRAM found at %pR\n", res);
> +		return -EPROTO;
> +	} else if (copy_len > resource_size(res)) {
> +		dev_err(dev, "NVRAM size exceeds %pR\n", res);
> +		return -ERANGE;
> +	} else if (copy_len >= NVRAM_SPACE) {
> +		dev_err(dev, "NVRAM size exceeds buffer size %d\n", NVRAM_SPACE);
> +		return -ENOMEM;
> +	}
> +
> +	__ioread32_copy(nvram_buf, mmio, copy_len);
> +	nvram_buf[NVRAM_SPACE - 1] = '\0';
> +
> +	iounmap(mmio);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id brcm_nvram_of_match[] = {
> +	{ .compatible = "brcm,nvram "},
> +	{},
> +};
> +
> +static struct platform_driver brcm_nvram_driver = {
> +	.driver = {
> +		.name = "brcm_nvram",
> +		.of_match_table = brcm_nvram_of_match,
> +	},
> +	.probe	= brcm_nvram_probe,
> +};
> +
> +module_platform_driver(brcm_nvram_driver);
> +
>  int bcm47xx_nvram_getenv(const char *name, char *val, size_t val_len)
>  {
>  	char *var, *value, *end, *eq;
> 


-- 
Florian