From: Al Stone <al.st...@linaro.org>

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 <grant.lik...@linaro.org>
Signed-off-by: Al Stone <al.st...@linaro.org>
Signed-off-by: Graeme Gregory <graeme.greg...@linaro.org>
Signed-off-by: Hanjun Guo <hanjun....@linaro.org>
---
 Documentation/kernel-parameters.txt |    3 ++-
 drivers/acpi/plat/arm-core.c        |   21 +++++++++++++++++++++
 2 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/Documentation/kernel-parameters.txt 
b/Documentation/kernel-parameters.txt
index 8849049..b7e9fc0 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/drivers/acpi/plat/arm-core.c b/drivers/acpi/plat/arm-core.c
index c6c7e03..cf46c25 100644
--- a/drivers/acpi/plat/arm-core.c
+++ b/drivers/acpi/plat/arm-core.c
@@ -108,3 +108,24 @@ 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;
+       } else {
+               /* Core will printk when we return error */
+               return -EINVAL;
+       }
+
+       return 0;
+}
+early_param("acpi", parse_acpi);
-- 
1.7.9.5

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