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authorAl Stone <al.stone@linaro.org>2015-03-24 14:02:41 +0000
committerWill Deacon <will.deacon@arm.com>2015-03-25 11:49:31 +0000
commitb10d79f76085b577673395daf92d6208ae09196f (patch)
treef712d5dd353304d38211b07b7f0fc790a9bb2964 /arch/arm64
parenta9cb97fe71d84df103994861f00112fe2cba91be (diff)
downloadop-kernel-dev-b10d79f76085b577673395daf92d6208ae09196f.zip
op-kernel-dev-b10d79f76085b577673395daf92d6208ae09196f.tar.gz
ARM64 / ACPI: Introduce early_param "acpi=" to enable/disable ACPI
This implements the following policy to decide whether ACPI should be used to boot the system: - acpi=off: ACPI will not be used to boot the system, even if there is no alternative available (e.g., device tree is empty) - acpi=force: only ACPI will be used to boot the system; if that fails, there will be no fallback to alternative methods (such as device tree) - otherwise, ACPI will be used as a fallback if the device tree turns out to lack a platform description; the heuristic to decide this is whether /chosen is the only node present at depth 1 CC: Catalin Marinas <catalin.marinas@arm.com> CC: Will Deacon <will.deacon@arm.com> CC: Rafael J. Wysocki <rjw@rjwysocki.net> Acked-by: Olof Johansson <olof@lixom.net> Acked-by: Grant Likely <grant.likely@linaro.org> Tested-by: Timur Tabi <timur@codeaurora.org> 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> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Will Deacon <will.deacon@arm.com>
Diffstat (limited to 'arch/arm64')
-rw-r--r--arch/arm64/include/asm/acpi.h7
-rw-r--r--arch/arm64/kernel/acpi.c52
2 files changed, 54 insertions, 5 deletions
diff --git a/arch/arm64/include/asm/acpi.h b/arch/arm64/include/asm/acpi.h
index 40e0924..c5a9b97 100644
--- a/arch/arm64/include/asm/acpi.h
+++ b/arch/arm64/include/asm/acpi.h
@@ -39,6 +39,13 @@ 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
diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c
index 7abac24..2269e30 100644
--- a/arch/arm64/kernel/acpi.c
+++ b/arch/arm64/kernel/acpi.c
@@ -22,15 +22,49 @@
#include <linux/irq.h>
#include <linux/irqdomain.h>
#include <linux/memblock.h>
+#include <linux/of_fdt.h>
#include <linux/smp.h>
-int acpi_noirq; /* skip ACPI IRQ initialization */
-int acpi_disabled;
+int acpi_noirq = 1; /* skip ACPI IRQ initialization */
+int acpi_disabled = 1;
EXPORT_SYMBOL(acpi_disabled);
-int acpi_pci_disabled; /* skip ACPI PCI scan and IRQ initialization */
+int acpi_pci_disabled = 1; /* skip ACPI PCI scan and IRQ initialization */
EXPORT_SYMBOL(acpi_pci_disabled);
+static bool param_acpi_off __initdata;
+static bool param_acpi_force __initdata;
+
+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)
+ param_acpi_off = true;
+ else if (strcmp(arg, "force") == 0) /* force ACPI to be enabled */
+ param_acpi_force = true;
+ else
+ return -EINVAL; /* Core will print when we return error */
+
+ return 0;
+}
+early_param("acpi", parse_acpi);
+
+static int __init dt_scan_depth1_nodes(unsigned long node,
+ const char *uname, int depth,
+ void *data)
+{
+ /*
+ * Return 1 as soon as we encounter a node at depth 1 that is
+ * not the /chosen node.
+ */
+ if (depth == 1 && (strcmp(uname, "chosen") != 0))
+ return 1;
+ return 0;
+}
+
/*
* __acpi_map_table() will be called before page_init(), so early_ioremap()
* or early_memremap() should be called here to for ACPI table mapping.
@@ -83,10 +117,18 @@ static int __init acpi_parse_fadt(struct acpi_table_header *table)
*/
void __init acpi_boot_table_init(void)
{
- /* If acpi_disabled, bail out */
- if (acpi_disabled)
+ /*
+ * Enable ACPI instead of device tree unless
+ * - ACPI has been disabled explicitly (acpi=off), or
+ * - the device tree is not empty (it has more than just a /chosen node)
+ * and ACPI has not been force enabled (acpi=force)
+ */
+ if (param_acpi_off ||
+ (!param_acpi_force && of_scan_flat_dt(dt_scan_depth1_nodes, NULL)))
return;
+ enable_acpi();
+
/* Initialize the ACPI boot-time table parser. */
if (acpi_table_init()) {
disable_acpi();
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