[PATCH v2 05/18] ARM64 / ACPI: Parse FADT table to get PSCI flags for PSCI init

[Hanjun Guo <hanjun.guo@linaro.org>]

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@linaro.org>
Signed-off-by: Graeme Gregory <graeme.gregory@linaro.org>
---
 arch/arm64/include/asm/acpi.h |   12 ++++++
 arch/arm64/kernel/acpi.c      |   37 +++++++++++++++++
 arch/arm64/kernel/psci.c      |   89 ++++++++++++++++++++++++++++++-----------
 arch/arm64/kernel/setup.c     |    2 +
 4 files changed, 117 insertions(+), 23 deletions(-)

diff --git a/arch/arm64/include/asm/acpi.h b/arch/arm64/include/asm/acpi.h
index 6400312..6e04868 100644
--- a/arch/arm64/include/asm/acpi.h
+++ b/arch/arm64/include/asm/acpi.h
@@ -19,6 +19,18 @@ extern int acpi_disabled;
 extern int acpi_noirq;
 extern int acpi_pci_disabled;
 
+/* 1 to indicate PSCI 0.2+ is implemented */
+static inline bool acpi_psci_present(void)
+{
+	return !!(acpi_gbl_FADT.arm_boot_flags & ACPI_FADT_PSCI_COMPLIANT);
+}
+
+/* 1 to indicate HVC must be used instead of SMC as the PSCI conduit */
+static inline bool acpi_psci_use_hvc(void)
+{
+	return !!(acpi_gbl_FADT.arm_boot_flags & ACPI_FADT_PSCI_USE_HVC);
+}
+
 static inline void disable_acpi(void)
 {
 	acpi_disabled = 1;
diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c
index 9cf9127..69a315d 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>
@@ -47,6 +49,26 @@ void __init __acpi_unmap_table(char *map, unsigned long size)
 	early_memunmap(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_revision < 1) {
+		pr_info("FADT version is %d.%d, no PSCI support, should be 5.1 or higher\n",
+			table->revision, fadt->minor_revision);
+		disable_acpi();
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
 /*
  * acpi_boot_table_init() called from setup_arch(), always.
  *	1. find RSDP and get its address, and then find XSDT
@@ -68,6 +90,21 @@ 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;
+}
+
 /*
  * acpi_suspend_lowlevel() - save kernel state and suspend.
  *
diff --git a/arch/arm64/kernel/psci.c b/arch/arm64/kernel/psci.c
index 9e9798f..2ad2084 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 +339,40 @@ out_put_node:
 	return err;
 }
 
+#ifdef CONFIG_ACPI
+static int get_set_conduit_method_acpi(void)
+{
+	pr_info("probing for conduit method from ACPI.\n");
+
+	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)
+{
+	if (!acpi_psci_present()) {
+		pr_info("is not implemented in ACPI.\n");
+		return -EOPNOTSUPP;
+	}
+
+	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},
@@ -345,6 +385,9 @@ int __init psci_init(void)
 	const struct of_device_id *matched_np;
 	psci_initcall_t init_fn;
 
+	if (!acpi_disabled)
+		return psci_0_2_init_acpi();
+
 	np = of_find_matching_node_and_match(NULL, psci_of_match, &matched_np);
 
 	if (!np)
diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
index 85c6326..dfc4e4f3 100644
--- a/arch/arm64/kernel/setup.c
+++ b/arch/arm64/kernel/setup.c
@@ -395,6 +395,8 @@ void __init setup_arch(char **cmdline_p)
 	efi_idmap_init();
 
 	cpu_logical_map(0) = read_cpuid_mpidr() & MPIDR_HWID_BITMASK;
+	acpi_boot_init();
+
 	unflatten_device_tree();
 
 	psci_init();
-- 
1.7.9.5