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author | Al Stone <al.stone@linaro.org> | 2015-03-24 14:02:41 +0000 |
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committer | Will Deacon <will.deacon@arm.com> | 2015-03-25 11:49:31 +0000 |
commit | b10d79f76085b577673395daf92d6208ae09196f (patch) | |
tree | f712d5dd353304d38211b07b7f0fc790a9bb2964 /arch/arm64/kernel/acpi.c | |
parent | a9cb97fe71d84df103994861f00112fe2cba91be (diff) | |
download | linux-stable-b10d79f76085b577673395daf92d6208ae09196f.tar.gz linux-stable-b10d79f76085b577673395daf92d6208ae09196f.tar.bz2 linux-stable-b10d79f76085b577673395daf92d6208ae09196f.zip |
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/kernel/acpi.c')
-rw-r--r-- | arch/arm64/kernel/acpi.c | 52 |
1 files changed, 47 insertions, 5 deletions
diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c index 7abac24d5584..2269e3032c07 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(); |