[PATCH v4 06/18] ARM64 / ACPI: Introduce early_param for "acpi"

Hanjun Guo
2014-09-12T14:00:04Z

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

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

This ensures the kernel uses the DT on a platform that provides both
ACPI tables and DT.

Signed-off-by: Al Stone <al.stone@linaro.org>
Signed-off-by: Graeme Gregory <graeme.gregory@linaro.org>
Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>
---
Documentation/kernel-parameters.txt | 3 ++-
arch/arm64/kernel/acpi.c | 15 +++++++++++++++
2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 5ae8608..9dfb1d8 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 "acpi=off" is 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 9252f72..693da7f 100644
--- a/arch/arm64/kernel/acpi.c
+++ b/arch/arm64/kernel/acpi.c
@@ -67,3 +67,18 @@ 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
+ return -EINVAL; /* Core will print when we return error */
+
+ return 0;
+}
+early_param("acpi", parse_acpi);
--
1.7.9.5