Re: [PATCH v9 09/21] ARM64 / ACPI: Introduce early_param "acpi=" to enable/disable ACPI

[Grant Likely <grant.likely@linaro.org>]

On Wed, 25 Feb 2015 16:39:49 +0800
, Hanjun Guo <hanjun.guo@linaro.org>
 wrote:
> From: Al Stone <al.stone@linaro.org>
> 
> This implements the following policy to decide whether ACPI should
> be used to boot the system:
> - acpi=off: ACPI will not be used to boot the system, even if there is
>   no alternative available (e.g., device tree is empty)
> - acpi=force: only ACPI will be used to boot the system; if that fails,
>   there will be no fallback to alternative methods (such as device tree)
> - otherwise, ACPI will be used as a fallback if the device tree turns out
>   to lack a platform description; the heuristic to decide this is whether
>   /chosen is the only node present at depth 1
> 
> CC: Catalin Marinas <catalin.marinas@arm.com>
> CC: Will Deacon <will.deacon@arm.com>
> CC: Rafael J. Wysocki <rjw@rjwysocki.net>
> Signed-off-by: Al Stone <al.stone@linaro.org>
> Signed-off-by: Graeme Gregory <graeme.gregory@linaro.org>
> Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>

Acked-by: Grant Likely <grant.likely@linaro.org>

> ---
>  Documentation/kernel-parameters.txt |  3 ++-
>  arch/arm64/include/asm/acpi.h       |  7 +++++
>  arch/arm64/kernel/acpi.c            | 52 +++++++++++++++++++++++++++++++++----
>  3 files changed, 56 insertions(+), 6 deletions(-)
> 
> diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
> index bfcb1a6..d6c35a7 100644
> --- a/Documentation/kernel-parameters.txt
> +++ b/Documentation/kernel-parameters.txt
> @@ -165,7 +165,7 @@ multipliers 'Kilo', 'Mega', and 'Giga', equalling 2^10, 2^20, and 2^30
>  bytes respectively. Such letter suffixes can also be entirely omitted.
>  
>  
> -	acpi=		[HW,ACPI,X86]
> +	acpi=		[HW,ACPI,X86,ARM64]
>  			Advanced Configuration and Power Interface
>  			Format: { force | off | strict | noirq | rsdt }
>  			force -- enable ACPI if default was off
> @@ -175,6 +175,7 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
>  				strictly ACPI specification compliant.
>  			rsdt -- prefer RSDT over (default) XSDT
>  			copy_dsdt -- copy DSDT to memory
> +			For ARM64, ONLY "acpi=off" or "acpi=force" are available
>  
>  			See also Documentation/power/runtime_pm.txt, pci=noacpi
>  
> diff --git a/arch/arm64/include/asm/acpi.h b/arch/arm64/include/asm/acpi.h
> index 40e0924..c5a9b97 100644
> --- a/arch/arm64/include/asm/acpi.h
> +++ b/arch/arm64/include/asm/acpi.h
> @@ -39,6 +39,13 @@ static inline void disable_acpi(void)
>  	acpi_noirq = 1;
>  }
>  
> +static inline void enable_acpi(void)
> +{
> +	acpi_disabled = 0;
> +	acpi_pci_disabled = 0;
> +	acpi_noirq = 0;
> +}
> +
>  /*
>   * It's used from ACPI core in kdump to boot UP system with SMP kernel,
>   * with this check the ACPI core will not override the CPU index
> diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c
> index f052e7a..bdcc9fc 100644
> --- a/arch/arm64/kernel/acpi.c
> +++ b/arch/arm64/kernel/acpi.c
> @@ -22,15 +22,49 @@
>  #include <linux/irq.h>
>  #include <linux/irqdomain.h>
>  #include <linux/memblock.h>
> +#include <linux/of_fdt.h>
>  #include <linux/smp.h>
>  
> -int acpi_noirq;			/* skip ACPI IRQ initialization */
> -int acpi_disabled;
> +int acpi_noirq = 1;		/* skip ACPI IRQ initialization */
> +int acpi_disabled = 1;
>  EXPORT_SYMBOL(acpi_disabled);
>  
> -int acpi_pci_disabled;		/* skip ACPI PCI scan and IRQ initialization */
> +int acpi_pci_disabled = 1;	/* skip ACPI PCI scan and IRQ initialization */
>  EXPORT_SYMBOL(acpi_pci_disabled);
>  
> +static bool __initdata param_acpi_off;
> +static bool __initdata param_acpi_force;
> +
> +static int __init parse_acpi(char *arg)
> +{
> +	if (!arg)
> +		return -EINVAL;
> +
> +	/* "acpi=off" disables both ACPI table parsing and interpreter */
> +	if (strcmp(arg, "off") == 0)
> +		param_acpi_off = true;
> +	else if (strcmp(arg, "force") == 0) /* force ACPI to be enabled */
> +		param_acpi_force = true;
> +	else
> +		return -EINVAL;	/* Core will print when we return error */
> +
> +	return 0;
> +}
> +early_param("acpi", parse_acpi);
> +
> +static int __init dt_scan_depth1_nodes(unsigned long node,
> +				       const char *uname, int depth,
> +				       void *data)
> +{
> +	/*
> +	 * Return 1 as soon as we encounter a node at depth 1 that is
> +	 * not the /chosen node.
> +	 */
> +	if (depth == 1 && (strcmp(uname, "chosen") != 0))
> +		return 1;
> +	return 0;
> +}
> +
>  /*
>   * __acpi_map_table() will be called before page_init(), so early_ioremap()
>   * or early_memremap() should be called here to for ACPI table mapping.
> @@ -83,10 +117,18 @@ static int __init acpi_parse_fadt(struct acpi_table_header *table)
>   */
>  void __init acpi_boot_table_init(void)
>  {
> -	/* If acpi_disabled, bail out */
> -	if (acpi_disabled)
> +	/*
> +	 * Enable ACPI instead of device tree unless
> +	 * - ACPI has been disabled explicitly (acpi=off), or
> +	 * - the device tree is not empty (it has more than just a /chosen node)
> +	 *   and ACPI has not been force enabled (acpi=force)
> +	 */
> +	if (param_acpi_off ||
> +	    (!param_acpi_force && of_scan_flat_dt(dt_scan_depth1_nodes, NULL)))
>  		return;
>  
> +	enable_acpi();
> +
>  	/* Initialize the ACPI boot-time table parser. */
>  	if (acpi_table_init()) {
>  		disable_acpi();
> -- 
> 1.9.1
>