Commit b10d79f7 authored by Al Stone's avatar Al Stone Committed by Will Deacon
Browse files

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: default avatarOlof Johansson <olof@lixom.net>
Acked-by: default avatarGrant Likely <grant.likely@linaro.org>
Tested-by: default avatarTimur Tabi <timur@codeaurora.org>
Signed-off-by: default avatarAl Stone <al.stone@linaro.org>
Signed-off-by: default avatarGraeme Gregory <graeme.gregory@linaro.org>
Signed-off-by: default avatarHanjun Guo <hanjun.guo@linaro.org>
Signed-off-by: default avatarArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
parent a9cb97fe
......@@ -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,ARM64]
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" or "acpi=force" are available
See also Documentation/power/runtime_pm.txt, pci=noacpi
......
......@@ -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
......
......@@ -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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