linux-hardening - Re: [PATCH v5 4/8] soc/tegra: fuse: Add tegra_acpi_init

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Date: Mon, 16 Oct 2023 07:41:14 +0200
From: Christophe JAILLET <christophe.jaillet@...adoo.fr>
To: kkartik@...dia.com
Cc: akpm@...ux-foundation.org, andy@...nel.org, arnd@...db.de,
 frank.li@...o.com, jonathanh@...dia.com, keescook@...omium.org,
 linus.walleij@...aro.org, linux-hardening@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-mm@...ck.org,
 linux-tegra@...r.kernel.org, pdeschrijver@...dia.com, petlozup@...dia.com,
 pshete@...dia.com, robh@...nel.org, stefank@...dia.com,
 thierry.reding@...il.com, ulf.hansson@...aro.org
Subject: Re: [PATCH v5 4/8] soc/tegra: fuse: Add tegra_acpi_init_apbmisc()

Le 16/10/2023 à 07:34, Kartik a écrit :
> In preparation to ACPI support in Tegra fuse driver add function
> tegra_acpi_init_apbmisc() to initialize tegra-apbmisc driver.
> Also, document the reason of calling tegra_init_apbmisc() at early init.
> 
> Note that function tegra_acpi_init_apbmisc() is not placed in the __init
> section, because it will be called during probe.
> 
> Signed-off-by: Kartik <kkartik-DDmLM1+adcrQT0dZR+AlfA@...lic.gmane.org>
> ---
> v2 -> v3:
> 	* Fix build warnings seen when CONFIG_ACPI is disabled by moving
> 	  tegra_init_apbmisc table inside #ifdef CONFIG_ACPI block.
> 
> v1 -> v2:
> 	* Update ACPI ID table 'tegra_init_apbmisc'.
> 	* Add comment to document the reason to call tegra_init_apbmisc
> 	  at early init.
> 	* Fix an issue where acpi_dev_free_resource_list() and
> 	* acpi_dev_put() were not called if
> 	  acpi_dev_get_memory_resources() returned 1.
> 	* Update logic to fetch memory resources in
> 	  tegra_acpi_init_apbmisc().
> 	* Fix build errors seen when CONFIG_ACPI is disabled.
> ---
>   drivers/soc/tegra/fuse/fuse.h          |  1 +
>   drivers/soc/tegra/fuse/tegra-apbmisc.c | 72 ++++++++++++++++++++++++++
>   2 files changed, 73 insertions(+)
> 
> diff --git a/drivers/soc/tegra/fuse/fuse.h b/drivers/soc/tegra/fuse/fuse.h
> index 90f23be73894..a41e9f85281a 100644
> --- a/drivers/soc/tegra/fuse/fuse.h
> +++ b/drivers/soc/tegra/fuse/fuse.h
> @@ -69,6 +69,7 @@ struct tegra_fuse {
>   
>   void tegra_init_revision(void);
>   void tegra_init_apbmisc(void);
> +void tegra_acpi_init_apbmisc(void);
>   
>   u32 __init tegra_fuse_read_spare(unsigned int spare);
>   u32 __init tegra_fuse_read_early(unsigned int offset);
> diff --git a/drivers/soc/tegra/fuse/tegra-apbmisc.c b/drivers/soc/tegra/fuse/tegra-apbmisc.c
> index 06c1b3a2c7ec..e2ca93de6c1f 100644
> --- a/drivers/soc/tegra/fuse/tegra-apbmisc.c
> +++ b/drivers/soc/tegra/fuse/tegra-apbmisc.c
> @@ -3,9 +3,11 @@
>    * Copyright (c) 2014-2023, NVIDIA CORPORATION.  All rights reserved.
>    */
>   
> +#include <linux/acpi.h>
>   #include <linux/export.h>
>   #include <linux/io.h>
>   #include <linux/kernel.h>
> +#include <linux/mod_devicetable.h>
>   #include <linux/of.h>
>   #include <linux/of_address.h>
>   
> @@ -180,6 +182,12 @@ static void tegra_init_apbmisc_resources(struct resource *apbmisc,
>   	}
>   }
>   
> +/**
> + * tegra_init_apbmisc - Initializes Tegra APBMISC and Strapping registers.
> + *
> + * This is called during early init as some of the old 32-bit ARM code needs
> + * information from the APBMISC registers very early during boot.
> + */
>   void __init tegra_init_apbmisc(void)
>   {
>   	struct resource apbmisc, straps;
> @@ -244,3 +252,67 @@ void __init tegra_init_apbmisc(void)
>   put:
>   	of_node_put(np);
>   }
> +
> +#ifdef CONFIG_ACPI
> +static const struct acpi_device_id apbmisc_acpi_match[] = {
> +	{ "NVDA2010" },
> +	{ /* sentinel */ }
> +};
> +
> +void tegra_acpi_init_apbmisc(void)
> +{
> +	struct resource *resources[2] = { NULL };
> +	struct resource_entry *rentry, *tmp;
> +	struct acpi_device *adev = NULL;
> +	struct list_head resource_list;
> +	int rcount = 0;
> +	int ret;
> +
> +	adev = acpi_dev_get_first_match_dev(apbmisc_acpi_match[0].id, NULL, -1);
> +	if (!adev)
> +		return;
> +
> +	INIT_LIST_HEAD(&resource_list);
> +
> +	ret = acpi_dev_get_memory_resources(adev, &resource_list);
> +	if (ret < 0) {
> +		pr_err("failed to get APBMISC memory resources");
> +		goto out_put_acpi_dev;
> +	}
> +
> +	/*
> +	 * Get required memory resources.
> +	 *
> +	 * resources[0]: apbmisc.
> +	 * resources[1]: straps.
> +	 */
> +	resource_list_for_each_entry_safe(rentry, tmp, &resource_list) {

Nit: Is the 'safe' version really needed here?

CJ

> +		if (rcount >= ARRAY_SIZE(resources))
> +			break;
> +
> +		resources[rcount++] = rentry->res;
> +	}
> +
> +	if (!resources[0]) {
> +		pr_err("failed to get APBMISC registers\n");
> +		goto out_free_resource_list;
> +	}
> +
> +	if (!resources[1]) {
> +		pr_err("failed to get strapping options registers\n");
> +		goto out_free_resource_list;
> +	}
> +
> +	tegra_init_apbmisc_resources(resources[0], resources[1]);
> +
> +out_free_resource_list:
> +	acpi_dev_free_resource_list(&resource_list);
> +
> +out_put_acpi_dev:
> +	acpi_dev_put(adev);
> +}
> +#else
> +void tegra_acpi_init_apbmisc(void)
> +{
> +}
> +#endif