[PATCH v5 06/18] ARM64 / ACPI: Introduce early_param for "acpi" and pass acpi=force to enable ACPI

[Hanjun Guo]

From: Al Stone <al.stone at linaro.org>

Introduce one early parameters "off" and "force" for "acpi", acpi=off
will be the default behavior for ARM64, so introduce acpi=force to
enable ACPI on ARM64.

Disable ACPI before early parameters parsed, and enable it to pass
"acpi=force" if people want use ACPI on ARM64. This ensures DT be
the prefer one if ACPI table and DT both are provided at this moment.

Signed-off-by: Al Stone <al.stone at linaro.org>
Signed-off-by: Graeme Gregory <graeme.gregory at linaro.org>
Signed-off-by: Hanjun Guo <hanjun.guo at linaro.org>
---
 Documentation/kernel-parameters.txt |    3 ++-
 arch/arm64/include/asm/acpi.h       |    9 +++++++++
 arch/arm64/kernel/acpi.c            |   17 +++++++++++++++++
 arch/arm64/kernel/setup.c           |    3 +++
 4 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 5ae8608..2af0948 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 8b837ab..496c33b 100644
--- a/arch/arm64/include/asm/acpi.h
+++ b/arch/arm64/include/asm/acpi.h
@@ -26,6 +26,13 @@ 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
@@ -40,6 +47,8 @@ static inline bool acpi_has_cpu_in_madt(void)
 
 static inline void arch_fix_phys_package_id(int num, u32 slot) { }
 
+#else
+static inline void disable_acpi(void) { }
 #endif /* CONFIG_ACPI */
 
 #endif /*_ASM_ACPI_H*/
diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c
index 9252f72..39a1655 100644
--- a/arch/arm64/kernel/acpi.c
+++ b/arch/arm64/kernel/acpi.c
@@ -67,3 +67,20 @@ void __init acpi_boot_table_init(void)
 	if (acpi_table_init())
 		disable_acpi();
 }
+
+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)
+		disable_acpi();
+	else if (strcmp(arg, "force") == 0) /* force ACPI to be enabled */
+		enable_acpi();
+	else
+		return -EINVAL;	/* Core will print when we return error */
+
+	return 0;
+}
+early_param("acpi", parse_acpi);
diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
index 5b05227..15621b9 100644
--- a/arch/arm64/kernel/setup.c
+++ b/arch/arm64/kernel/setup.c
@@ -60,6 +60,7 @@
 #include <asm/memblock.h>
 #include <asm/psci.h>
 #include <asm/efi.h>
+#include <asm/acpi.h>
 
 unsigned int processor_id;
 EXPORT_SYMBOL(processor_id);
@@ -384,6 +385,8 @@ void __init setup_arch(char **cmdline_p)
 
 	early_ioremap_init();
 
+	disable_acpi();
+
 	parse_early_param();
 
 	efi_init();
-- 
1.7.9.5