From: Al Stone <redacted>

Introduce two early parameters for "acpi", one is the parameter
to disable ACPI on ARM64 and another one is acpi=strict to disable
out-of-spec workarounds.

Reviewed-by: Grant Likely <redacted>
Signed-off-by: Al Stone <redacted>
Signed-off-by: Graeme Gregory <redacted>
Signed-off-by: Hanjun Guo <redacted>
---
  Documentation/kernel-parameters.txt |    3 ++-
  arch/arm64/kernel/acpi.c            |   21 +++++++++++++++++++++
  2 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index b7fa2f5..d130bd5 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,ARM]
  			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 "off" and "strict" are available.

  			See also Documentation/power/runtime_pm.txt, pci=noacpi

diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c
index c62fce6..ac78e4e 100644
--- a/arch/arm64/kernel/acpi.c
+++ b/arch/arm64/kernel/acpi.c

@@ -74,3 +74,24 @@ void __init acpi_boot_table_init(void)
  		return;
  	}
  }
+
+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();
+	}
+	/* acpi=strict disables out-of-spec workarounds */
+	else if (strcmp(arg, "strict") == 0) {
+		acpi_strict = 1;