[PATCH v2 15/18] ARM64 / ACPI: Introduce early_param for "acpi" and set ACPI default off

[Hanjun Guo]

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

Introduce one early parameters "on" for "acpi" to enable ACPI on
ARM64.

Disable ACPI before early parameters parsed, and enable it to pass
"acpi=on" if people want use ACPI on ARM64.

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 |    5 +++--
 arch/arm64/include/asm/acpi.h       |    9 +++++++++
 arch/arm64/kernel/acpi.c            |   17 +++++++++++++++++
 arch/arm64/kernel/setup.c           |    3 +++
 4 files changed, 32 insertions(+), 2 deletions(-)

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index b7fa2f5..1f63156 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -165,9 +165,9 @@ 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,ARM]
 			Advanced Configuration and Power Interface
-			Format: { force | off | strict | noirq | rsdt }
+			Format: { force | off | strict | noirq | rsdt | on}
 			force -- enable ACPI if default was off
 			off -- disable ACPI if default was on
 			noirq -- do not use ACPI for IRQ routing
@@ -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
+			"acpi=on" is ONLY available for ARM64.
 
 			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 009303d..0f2c51a 100644
--- a/arch/arm64/include/asm/acpi.h
+++ b/arch/arm64/include/asm/acpi.h
@@ -61,6 +61,13 @@ 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;
+}
+
 u32 pack_mpidr_into_32_bits(u64 mpidr);
 
 /*
@@ -99,6 +106,8 @@ static inline void arch_fix_phys_package_id(int num, u32 slot) { }
 extern int (*acpi_suspend_lowlevel)(void);
 #define acpi_wakeup_address 0
 
+#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 988fea2..585d08c 100644
--- a/arch/arm64/kernel/acpi.c
+++ b/arch/arm64/kernel/acpi.c
@@ -361,3 +361,20 @@ u32 pack_mpidr_into_32_bits(u64 mpidr)
  * TBD when ARM/ARM64 starts to support suspend...
  */
 int (*acpi_suspend_lowlevel)(void) = NULL;
+
+static int __init parse_acpi(char *arg)
+{
+	if (!arg)
+		return -EINVAL;
+
+	/* "acpi=on" enables both ACPI table parsing and interpreter */
+	if (strcmp(arg, "on") == 0) {
+		enable_acpi();
+	} else {
+		/* Core will printk when we return error */
+		return -EINVAL;
+	}
+
+	return 0;
+}
+early_param("acpi", parse_acpi);
diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
index dfc4e4f3..056e2e1 100644
--- a/arch/arm64/kernel/setup.c
+++ b/arch/arm64/kernel/setup.c
@@ -59,6 +59,7 @@
 #include <asm/memblock.h>
 #include <asm/psci.h>
 #include <asm/efi.h>
+#include <asm/acpi.h>
 
 unsigned int processor_id;
 EXPORT_SYMBOL(processor_id);
@@ -380,6 +381,8 @@ void __init setup_arch(char **cmdline_p)
 	*cmdline_p = boot_command_line;
 
 	early_ioremap_init();
+	
+	disable_acpi();
 
 	parse_early_param();
 
-- 
1.7.9.5