ACPI currently accesses resources it should not when cores=1 and Hardware Reduced is set in FACP

[Graeme Gregory]

When FACP Hardware Reduced flag is set ACPI drivers should not be accessing power management registers directly.

This bug only seems to trigger on arm when booting with a single core.

This produces an Ooops similar to

    [ 37.822312] [<80229bb2>] (acpi_os_read_port+0x22/0x42) from [<80239dff>] (acpi_hw_read_port+0x2b/0x6c)
    [ 37.822549] [<80239dff>] (acpi_hw_read_port+0x2b/0x6c) from [<8023988b>] (acpi_hw_read+0x37/0x3a)
    [ 37.822784] [<8023988b>] (acpi_hw_read+0x37/0x3a) from [<802398a9>] (acpi_hw_read_multiple+0x1b/0x48)
    [ 37.823025] [<802398a9>] (acpi_hw_read_multiple+0x1b/0x48) from [<802399dd>] (acpi_hw_register_read+0x35/0xb0)
    [ 37.823271] [<802399dd>] (acpi_hw_register_read+0x35/0xb0) from [<80239eff>] (acpi_write_bit_register+0x29/0x76)
    [ 37.823503] [<80239eff>] (acpi_write_bit_register+0x29/0x76) from [<80232913>] (acpi_ev_initialize_events+0x37/0x88)
    [ 37.823719] [<80232913>] (acpi_ev_initialize_events+0x37/0x88) from [<80243da9>] (acpi_enable_subsystem+0x4d/0x70)
    [ 37.823936] [<80243da9>] (acpi_enable_subsystem+0x4d/0x70) from [<804876dd>] (acpi_init+0x3d/0x1e8)
    [ 37.824142] [<804876dd>] (acpi_init+0x3d/0x1e8) from [<80008687>] (do_one_initcall+0x2f/0x114)
    [ 37.824368] [<80008687>] (do_one_initcall+0x2f/0x114) from [<8046d92b>] (kernel_init_freeable+0xcb/0x15c)
    [ 37.824596] [<8046d92b>] (kernel_init_freeable+0xcb/0x15c) from [<802f4475>] (kernel_init+0xd/0xa0)
    [ 37.824805] [<802f4475>] (kernel_init+0xd/0xa0) from [<8000ccbd>] (ret_from_fork+0x11/0x20)

[hanjun.guo (hanjun-guo)]

after a long discussion with Robert Moore and Lv Zheng form intel (they are ACPICA maintainer), they agreed to introduce a kernel config for the ACPI_HARDWARE_REDUCED macro, some thing like:

From b10bc1d2f9a3ff09abfb6990412aa1cf62d56937 Mon Sep 17 00:00:00 2001
From: Hanjun Guo <email address hidden>
Date: Wed, 18 Sep 2013 17:19:23 +0800
Subject: [PATCH] ACPI: Introduce CONFIG_ACPI_REDUCED_HARDWARE to enable
 reduced hardware

If we want to enable reduced hardware ACPI on some platform (such as ARM),
we need to modify the kernel code and set ACPI_REDUCED_HARDWARE to TRUE.

This is not reasonable, so introduce a kernel config to enable it, and
no need for kernel modification when we use hardware-reduced ACPI.

Signed-off-by: Hanjun Guo <email address hidden>
---
 drivers/acpi/Kconfig | 8 ++++++++
 include/acpi/acconfig.h | 4 ++++
 2 files changed, 12 insertions(+)

diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig
index 0d7f6eb..1232a7b 100644
--- a/drivers/acpi/Kconfig
+++ b/drivers/acpi/Kconfig
@@ -413,6 +413,14 @@ config ACPI_BGRT
          data from the firmware boot splash. It will appear under
          /sys/firmware/acpi/bgrt/ .

+config ACPI_REDUCED_HARDWARE
+ bool "Hardware-reduced ACPI support"
+ depends on ARM || ARM64
+ help
+ This config adds support for Hardware-reduced ACPI. When this option
+ is selected, will generate a specialized version of ACPICA that ONLY
+ supports the ACPI 5.0 "reduced hardware".
+
 source "drivers/acpi/apei/Kconfig"

 endif # ACPI
diff --git a/include/acpi/acconfig.h b/include/acpi/acconfig.h
index 1c16f82..15254f5 100644
--- a/include/acpi/acconfig.h
+++ b/include/acpi/acconfig.h
@@ -100,7 +100,11 @@
  * ACPI PM timer
  * FACS table (Waking vectors and Global Lock)
  */
+#ifdef CONFIG_ACPI_REDUCED_HARDWARE
+#define ACPI_REDUCED_HARDWARE TRUE
+#else
 #define ACPI_REDUCED_HARDWARE FALSE
+#endif /* CONFIG_ACPI_REDUCED_HARDWARE */

 /******************************************************************************
  *
-- 1.7.9.5