[PATCH v4 1/2] ACPI / x86: boot: Not all platforms require acpi_reduced_hw_init()

[Andy Shevchenko]

Some platforms might take care of legacy devices on theirs own. Due to this,
export acpi_reduced_hw_init() and put it into struct x86_init_acpi.

While doing this, rename acpi_reduced_hw_init() to
acpi_reduced_hw_early_init() to show the stage at which it's called.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
---

- re-done based on patches from Juergen Gross
- supposed to go via tip tree (x86/boot branch)
- tested on ASuS T100ta (HW reduced) and Intel Broxton based platforms

 arch/x86/include/asm/acpi.h     |  4 ++++
 arch/x86/include/asm/x86_init.h |  2 ++
 arch/x86/kernel/acpi/boot.c     | 21 ++++++++++-----------
 arch/x86/kernel/x86_init.c      |  2 ++
 4 files changed, 18 insertions(+), 11 deletions(-)

diff --git a/arch/x86/include/asm/acpi.h b/arch/x86/include/asm/acpi.h
index 6609dd7289b5..f3f86be35fc5 100644
--- a/arch/x86/include/asm/acpi.h
+++ b/arch/x86/include/asm/acpi.h
@@ -140,6 +140,8 @@ static inline u64 acpi_arch_get_root_pointer(void)
 	return x86_init.acpi.get_root_pointer();
 }
 
+void acpi_reduced_hw_early_init(void);
+
 #else /* !CONFIG_ACPI */
 
 #define acpi_lapic 0
@@ -149,6 +151,8 @@ static inline void acpi_noirq_set(void) { }
 static inline void acpi_disable_pci(void) { }
 static inline void disable_acpi(void) { }
 
+static inline void acpi_reduced_hw_early_init(void) { }
+
 #endif /* !CONFIG_ACPI */
 
 #define ARCH_HAS_POWER_INIT	1
diff --git a/arch/x86/include/asm/x86_init.h b/arch/x86/include/asm/x86_init.h
index 5ffa116ddb08..199e15bd3ec5 100644
--- a/arch/x86/include/asm/x86_init.h
+++ b/arch/x86/include/asm/x86_init.h
@@ -133,9 +133,11 @@ struct x86_hyper_init {
 /**
  * struct x86_init_acpi - x86 ACPI init functions
  * @get_root_pointer:		get RSDP address
+ * @reduced_hw_early_init:	hardware reduced platform early init
  */
 struct x86_init_acpi {
 	u64 (*get_root_pointer)(void);
+	void (*reduced_hw_early_init)(void);
 };
 
 /**
diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
index d3deae23e584..02acf1c58d3a 100644
--- a/arch/x86/kernel/acpi/boot.c
+++ b/arch/x86/kernel/acpi/boot.c
@@ -1378,17 +1378,15 @@ static int __init dmi_ignore_irq0_timer_override(const struct dmi_system_id *d)
  *
  * We initialize the Hardware-reduced ACPI model here:
  */
-static void __init acpi_reduced_hw_init(void)
+void __init acpi_reduced_hw_early_init(void)
 {
-	if (acpi_gbl_reduced_hardware) {
-		/*
-		 * Override x86_init functions and bypass legacy pic
-		 * in Hardware-reduced ACPI mode
-		 */
-		x86_init.timers.timer_init	= x86_init_noop;
-		x86_init.irqs.pre_vector_init	= x86_init_noop;
-		legacy_pic			= &null_legacy_pic;
-	}
+	/*
+	 * Override x86_init functions and bypass legacy pic
+	 * in Hardware-reduced ACPI mode.
+	 */
+	x86_init.timers.timer_init	= x86_init_noop;
+	x86_init.irqs.pre_vector_init	= x86_init_noop;
+	legacy_pic			= &null_legacy_pic;
 }
 
 /*
@@ -1593,7 +1591,8 @@ int __init early_acpi_boot_init(void)
 	/*
 	 * Hardware-reduced ACPI mode initialization:
 	 */
-	acpi_reduced_hw_init();
+	if (acpi_gbl_reduced_hardware)
+		x86_init.acpi.reduced_hw_early_init();
 
 	return 0;
 }
diff --git a/arch/x86/kernel/x86_init.c b/arch/x86/kernel/x86_init.c
index 32c288ebf870..8fd63640e764 100644
--- a/arch/x86/kernel/x86_init.c
+++ b/arch/x86/kernel/x86_init.c
@@ -8,6 +8,7 @@
 #include <linux/export.h>
 #include <linux/pci.h>
 
+#include <asm/acpi.h>
 #include <asm/bios_ebda.h>
 #include <asm/paravirt.h>
 #include <asm/pci_x86.h>
@@ -95,6 +96,7 @@ struct x86_init_ops x86_init __initdata = {
 
 	.acpi = {
 		.get_root_pointer	= u64_x86_init_noop,
+		.reduced_hw_early_init	= acpi_reduced_hw_early_init,
 	},
 };
 
-- 
2.15.1