Message-Id: <20140820150029.0BB3FC41205@trevor.secretlab.ca>
Date:	Wed, 20 Aug 2014 10:00:28 -0500
From:	Grant Likely <grant.likely@...aro.org>
To:	Hanjun Guo <hanjun.guo@...aro.org>,
	Catalin Marinas <catalin.marinas@....com>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Mark Rutland <mark.rutland@....com>
Cc:	Graeme Gregory <graeme.gregory@...aro.org>,
	Arnd Bergmann <arnd@...db.de>,
	Sudeep Holla <Sudeep.Holla@....com>,
	Will Deacon <will.deacon@....com>,
	Jason Cooper <jason@...edaemon.net>,
	Marc Zyngier <marc.zyngier@....com>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Daniel Lezcano <daniel.lezcano@...aro.org>,
	Mark Brown <broonie@...aro.org>,
	Robert Richter <rric@...nel.org>,
	Lv Zheng <lv.zheng@...el.com>,
	Robert Moore <robert.moore@...el.com>,
	Lorenzo Pieralisi <Lorenzo.Pieralisi@....com>,
	Liviu Dudau <Liviu.Dudau@....com>,
	Randy Dunlap <rdunlap@...radead.org>,
	Charles.Garcia-Tobin@....com, linux-acpi@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	linaro-acpi-private@...aro.org, Hanjun Guo <hanjun.guo@...aro.org>
Subject: Re: [PATCH 06/19] ARM64 / ACPI: Parse FADT table to get PSCI flags
 for PSCI init

On Thu, 24 Jul 2014 21:00:12 +0800, Hanjun Guo <hanjun.guo@...aro.org> wrote:
> There are two flags: PSCI_COMPLIANT and PSCI_USE_HVC. When set,
> the former signals to the OS that the hardware is PSCI compliant.
> The latter selects the appropriate conduit for PSCI calls by
> toggling between Hypervisor Calls (HVC) and Secure Monitor Calls
> (SMC).
> 
> FADT table contains such information, parse FADT to get the flags
> for PSCI init. Since ACPI 5.1 doesn't support self defined PSCI
> function IDs, which means that only PSCI 0.2+ is supported in ACPI.
> 
> At the same time, only ACPI 5.1 or higher verison supports PSCI,
> and FADT Major.Minor version was introduced in ACPI 5.1, so we
> will check the version and only parse FADT table with version >= 5.1.
> 
> If firmware provides ACPI tables with ACPI version less than 5.1,
> OS will be messed up with those information and have no way to
> bring up secondery CPUs, so disable ACPI if we get an FADT table
> with version less that 5.1.
> 
> Signed-off-by: Hanjun Guo <hanjun.guo@...aro.org>
> Signed-off-by: Graeme Gregory <graeme.gregory@...aro.org>
> ---
>  arch/arm64/include/asm/acpi.h |    2 +
>  arch/arm64/kernel/acpi.c      |   50 ++++++++++++++++++++++
>  arch/arm64/kernel/psci.c      |   95 +++++++++++++++++++++++++++++------------
>  arch/arm64/kernel/setup.c     |    2 +
>  4 files changed, 121 insertions(+), 28 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/acpi.h b/arch/arm64/include/asm/acpi.h
> index 44b617f..67dac90 100644
> --- a/arch/arm64/include/asm/acpi.h
> +++ b/arch/arm64/include/asm/acpi.h
> @@ -18,6 +18,8 @@ extern int acpi_disabled;
>  extern int acpi_noirq;
>  extern int acpi_pci_disabled;
>  extern int acpi_strict;
> +extern int acpi_psci_present;
> +extern int acpi_psci_use_hvc;
>  
>  static inline void disable_acpi(void)
>  {
> diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c
> index f5a10b5..374926f 100644
> --- a/arch/arm64/kernel/acpi.c
> +++ b/arch/arm64/kernel/acpi.c
> @@ -11,6 +11,8 @@
>   *  published by the Free Software Foundation.
>   */
>  
> +#define pr_fmt(fmt) "ACPI: " fmt
> +
>  #include <linux/init.h>
>  #include <linux/acpi.h>
>  #include <linux/cpumask.h>
> @@ -34,6 +36,12 @@ EXPORT_SYMBOL(acpi_disabled);
>  int acpi_pci_disabled;		/* skip ACPI PCI scan and IRQ initialization */
>  EXPORT_SYMBOL(acpi_pci_disabled);
>  
> +/* 1 to indicate PSCI is implemented */
> +int acpi_psci_present;
> +
> +/* 1 to indicate HVC must be used instead of SMC as the PSCI conduit */
> +int acpi_psci_use_hvc;
> +
>  /*
>   * __acpi_map_table() will be called before page_init(), so early_ioremap()
>   * or early_memremap() should be called here to for ACPI table mapping.
> @@ -54,6 +62,33 @@ void __init __acpi_unmap_table(char *map, unsigned long size)
>  	early_iounmap(map, size);
>  }
>  
> +static int __init acpi_parse_fadt(struct acpi_table_header *table)
> +{
> +	struct acpi_table_fadt *fadt = (struct acpi_table_fadt *)table;
> +
> +	/*
> +	 * Revision in table header is the FADT Major version,
> +	 * and there is a minor version of FADT which was introduced
> +	 * by ACPI 5.1, we only deal with ACPI 5.1 or higher version
> +	 * to get arm boot flags, or we will disable ACPI.
> +	 */
> +	if (table->revision < 5 || fadt->minor_version < 1) {
> +		pr_info("FADT version is %d.%d, no PSCI support, should be 5.1 or higher\n",
> +			table->revision, fadt->minor_version);
> +		acpi_psci_present = 0;
> +		disable_acpi();
> +		return -EINVAL;
> +	}
> +
> +	if (acpi_gbl_FADT.arm_boot_flags & ACPI_FADT_PSCI_COMPLIANT)
> +		acpi_psci_present = 1;
> +
> +	if (acpi_gbl_FADT.arm_boot_flags & ACPI_FADT_PSCI_USE_HVC)
> +		acpi_psci_use_hvc = 1;
> +
> +	return 0;
> +}
> +
>  /*
>   * acpi_boot_table_init() called from setup_arch(), always.
>   *	1. find RSDP and get its address, and then find XSDT
> @@ -75,6 +110,21 @@ void __init acpi_boot_table_init(void)
>  	}
>  }
>  
> +int __init acpi_boot_init(void)
> +{
> +	int err = 0;
> +
> +	/* If acpi_disabled, bail out */
> +	if (acpi_disabled)
> +		return -ENODEV;
> +
> +	err = acpi_table_parse(ACPI_SIG_FADT, acpi_parse_fadt);
> +	if (err)
> +		pr_err("Can't find FADT\n");
> +
> +	return err;
> +}
> +
>  static int __init parse_acpi(char *arg)
>  {
>  	if (!arg)
> diff --git a/arch/arm64/kernel/psci.c b/arch/arm64/kernel/psci.c
> index 9e9798f..adb25f3 100644
> --- a/arch/arm64/kernel/psci.c
> +++ b/arch/arm64/kernel/psci.c
> @@ -15,6 +15,7 @@
>  
>  #define pr_fmt(fmt) "psci: " fmt
>  
> +#include <linux/acpi.h>
>  #include <linux/init.h>
>  #include <linux/of.h>
>  #include <linux/smp.h>
> @@ -231,6 +232,33 @@ static void psci_sys_poweroff(void)
>  	invoke_psci_fn(PSCI_0_2_FN_SYSTEM_OFF, 0, 0, 0);
>  }
>  
> +static void psci_0_2_set_functions(void)
> +{
> +	pr_info("Using standard PSCI v0.2 function IDs\n");
> +	psci_function_id[PSCI_FN_CPU_SUSPEND] = PSCI_0_2_FN64_CPU_SUSPEND;
> +	psci_ops.cpu_suspend = psci_cpu_suspend;
> +
> +	psci_function_id[PSCI_FN_CPU_OFF] = PSCI_0_2_FN_CPU_OFF;
> +	psci_ops.cpu_off = psci_cpu_off;
> +
> +	psci_function_id[PSCI_FN_CPU_ON] = PSCI_0_2_FN64_CPU_ON;
> +	psci_ops.cpu_on = psci_cpu_on;
> +
> +	psci_function_id[PSCI_FN_MIGRATE] = PSCI_0_2_FN64_MIGRATE;
> +	psci_ops.migrate = psci_migrate;
> +
> +	psci_function_id[PSCI_FN_AFFINITY_INFO] = PSCI_0_2_FN64_AFFINITY_INFO;
> +	psci_ops.affinity_info = psci_affinity_info;
> +
> +	psci_function_id[PSCI_FN_MIGRATE_INFO_TYPE] =
> +		PSCI_0_2_FN_MIGRATE_INFO_TYPE;
> +	psci_ops.migrate_info_type = psci_migrate_info_type;
> +
> +	arm_pm_restart = psci_sys_reset;
> +
> +	pm_power_off = psci_sys_poweroff;
> +}
> +
>  /*
>   * PSCI Function IDs for v0.2+ are well defined so use
>   * standard values.
> @@ -264,29 +292,7 @@ static int psci_0_2_init(struct device_node *np)
>  		}
>  	}
>  
> -	pr_info("Using standard PSCI v0.2 function IDs\n");
> -	psci_function_id[PSCI_FN_CPU_SUSPEND] = PSCI_0_2_FN64_CPU_SUSPEND;
> -	psci_ops.cpu_suspend = psci_cpu_suspend;
> -
> -	psci_function_id[PSCI_FN_CPU_OFF] = PSCI_0_2_FN_CPU_OFF;
> -	psci_ops.cpu_off = psci_cpu_off;
> -
> -	psci_function_id[PSCI_FN_CPU_ON] = PSCI_0_2_FN64_CPU_ON;
> -	psci_ops.cpu_on = psci_cpu_on;
> -
> -	psci_function_id[PSCI_FN_MIGRATE] = PSCI_0_2_FN64_MIGRATE;
> -	psci_ops.migrate = psci_migrate;
> -
> -	psci_function_id[PSCI_FN_AFFINITY_INFO] = PSCI_0_2_FN64_AFFINITY_INFO;
> -	psci_ops.affinity_info = psci_affinity_info;
> -
> -	psci_function_id[PSCI_FN_MIGRATE_INFO_TYPE] =
> -		PSCI_0_2_FN_MIGRATE_INFO_TYPE;
> -	psci_ops.migrate_info_type = psci_migrate_info_type;
> -
> -	arm_pm_restart = psci_sys_reset;
> -
> -	pm_power_off = psci_sys_poweroff;
> +	psci_0_2_set_functions();
>  
>  out_put_node:
>  	of_node_put(np);
> @@ -333,6 +339,33 @@ out_put_node:
>  	return err;
>  }
>  
> +#ifdef CONFIG_ACPI
> +static int get_set_conduit_method_acpi(void)
> +{
> +	if (acpi_psci_use_hvc)
> +		invoke_psci_fn = __invoke_psci_fn_hvc;
> +	else
> +		invoke_psci_fn = __invoke_psci_fn_smc;
> +
> +	return 0;
> +}
> +
> +/* We use PSCI 0.2+ when ACPI is deployed */
> +static int psci_0_2_init_acpi(void)
> +{
> +	get_set_conduit_method_acpi();
> +
> +	psci_0_2_set_functions();
> +
> +	return 0;
> +}
> +#else
> +static inline int psci_0_2_init_acpi(void)
> +{
> +	return -ENODEV;
> +}
> +#endif
> +
>  static const struct of_device_id psci_of_match[] __initconst = {
>  	{ .compatible = "arm,psci",	.data = psci_0_1_init},
>  	{ .compatible = "arm,psci-0.2",	.data = psci_0_2_init},
> @@ -345,13 +378,19 @@ int __init psci_init(void)
>  	const struct of_device_id *matched_np;
>  	psci_initcall_t init_fn;
>  
> -	np = of_find_matching_node_and_match(NULL, psci_of_match, &matched_np);
> +	if (acpi_disabled) {
> +		np = of_find_matching_node_and_match(NULL,
> +				psci_of_match, &matched_np);
>  
> -	if (!np)
> -		return -ENODEV;
> +		if (!np)
> +			return -ENODEV;
> +
> +		init_fn = (psci_initcall_t)matched_np->data;
> +
> +		return init_fn(np);
> +	}
>  
> -	init_fn = (psci_initcall_t)matched_np->data;
> -	return init_fn(np);
> +	return psci_0_2_init_acpi();
>  }

So, while the functionality is sound, this is kind of a stinky diff. The
ACPI path should not push the OF code into a sub branch. Make it look
like this instead (with the advantage that the diff will be simpler):

+	if (IS_ENABLED(CONFIG_ACPI) && !acpi_disabled)
+		return psci_0_2_init_acpi();

 	np = of_find_matching_node_and_match(NULL, psci_of_match, &matched_np);
 
 	if (!np)
 		return -ENODEV;
 
 	init_fn = (psci_initcall_t)matched_np->data;
 	return init_fn(np);

g.
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