Re: [PATCH 01/19] ARM64 / ACPI: Get RSDP and ACPI boot-time tables

From: Graeme Gregory
Date: Mon Jul 28 2014 - 18:50:17 EST


On 28/07/2014 19:29, Sudeep Holla wrote:


On 24/07/14 14:00, Hanjun Guo wrote:
From: Al Stone <al.stone@xxxxxxxxxx>

As we want to get ACPI tables to parse and then use the information
for system initialization, we should get the RSDP (Root System
Description Pointer) first, it then locates Extended Root Description
Table (XSDT) which contains all the 64-bit physical address that
pointer to other boot-time tables.

Introduce acpi.c and its related head file in this patch to provide
fundamental needs of extern variables and functions for ACPI core,
and then get boot-time tables as needed.
- asm/cpu.h need for ACPI core and will be updated in the future to
add definitions for arch_(un)register_cpu which are required for
ACPI based physical CPU hotplug;
- asm/acenv.h for arch specific ACPICA environments and
implementation;
- asm/acpi.h for arch specific variables and functions needed by
ACPI driver core;
- acpi.c for ARM64 related ACPI implementation for ACPI driver
core;

acpi_boot_table_init() is introduced to get RSDP and boot-time tables,
it will be called in setup_arch() before paging_init(), so we should
use eary_memremap() mechanism here to get the RSDP and all the table
pointers.

Signed-off-by: Al Stone <al.stone@xxxxxxxxxx>
Signed-off-by: Graeme Gregory <graeme.gregory@xxxxxxxxxx>
Signed-off-by: Tomasz Nowicki <tomasz.nowicki@xxxxxxxxxx>
Signed-off-by: Hanjun Guo <hanjun.guo@xxxxxxxxxx>
---
arch/arm64/include/asm/acenv.h | 18 ++++++++++
arch/arm64/include/asm/acpi.h | 41 ++++++++++++++++++++++
arch/arm64/include/asm/cpu.h | 11 ++++++
arch/arm64/kernel/Makefile | 1 +
arch/arm64/kernel/acpi.c | 76 ++++++++++++++++++++++++++++++++++++++++
arch/arm64/kernel/setup.c | 4 +++
6 files changed, 151 insertions(+)
create mode 100644 arch/arm64/include/asm/acenv.h
create mode 100644 arch/arm64/include/asm/acpi.h
create mode 100644 arch/arm64/include/asm/cpu.h
create mode 100644 arch/arm64/kernel/acpi.c

diff --git a/arch/arm64/include/asm/acenv.h b/arch/arm64/include/asm/acenv.h
new file mode 100644
index 0000000..3899ee6
--- /dev/null
+++ b/arch/arm64/include/asm/acenv.h
@@ -0,0 +1,18 @@
+/*
+ * ARM64 specific ACPICA environments and implementation
+ *
+ * Copyright (C) 2014, Linaro Ltd.
+ * Author: Hanjun Guo <hanjun.guo@xxxxxxxxxx>
+ * Author: Graeme Gregory <graeme.gregory@xxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#ifndef _ASM_ACENV_H
+#define _ASM_ACENV_H
+
+#define ACPI_FLUSH_CPU_CACHE() WARN_ONCE(1, "Not currently supported on ARM64")
+
+#endif /* _ASM_ACENV_H */
diff --git a/arch/arm64/include/asm/acpi.h b/arch/arm64/include/asm/acpi.h
new file mode 100644
index 0000000..e8581ea
--- /dev/null
+++ b/arch/arm64/include/asm/acpi.h
@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2013-2014, Linaro Ltd.
+ * Author: Al Stone <al.stone@xxxxxxxxxx>
+ * Author: Graeme Gregory <graeme.gregory@xxxxxxxxxx>
+ * Author: Hanjun Guo <hanjun.guo@xxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation;
+ */
+
+#ifndef _ASM_ACPI_H
+#define _ASM_ACPI_H
+
+/* Basic configuration for ACPI */
+#ifdef CONFIG_ACPI
+extern int acpi_disabled;
+extern int acpi_noirq;
+extern int acpi_pci_disabled;
+extern int acpi_strict;

Until we need to enable workarounds, we should have acpi_strict
as macro rather than variable similar to IA64.

+
+static inline void disable_acpi(void)
+{
+ acpi_disabled = 1;
+ acpi_pci_disabled = 1;
+ acpi_noirq = 1;
+}
+
+/*
+ * MADT must provide at least one GICC structure
+ * for GIC initialization, so CPU will be
+ * always available in MADT on ARM64
+ */
+static inline bool acpi_has_cpu_in_madt(void)
+{
+ return 1;
+}
+

I don't see the user of this function in the series, it's better to
remove. Moreover the comment is so misleading. We will have CPU UID
not the CPU itself in MADT.

This is actually required for a patch that is now upstreamed. Comment should actually say that its checking for the posibility that the CPU can be initialised from the MADT. Its used from core in crash kernel case where boot CPU is not necessarily CPU0 like spec demands.

Graeme

+#endif /* CONFIG_ACPI */
+
+#endif /*_ASM_ACPI_H*/
diff --git a/arch/arm64/include/asm/cpu.h b/arch/arm64/include/asm/cpu.h
new file mode 100644
index 0000000..cee7d3f
--- /dev/null
+++ b/arch/arm64/include/asm/cpu.h
@@ -0,0 +1,11 @@
+/*
+ * Copyright (C) 2013-2014 ARM Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#ifndef __ASM_CPU_H
+#define __ASM_CPU_H
+
+#endif
diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile
index cdaedad..b568c26 100644
--- a/arch/arm64/kernel/Makefile
+++ b/arch/arm64/kernel/Makefile
@@ -29,6 +29,7 @@ arm64-obj-$(CONFIG_ARM64_CPU_SUSPEND) += sleep.o suspend.o
arm64-obj-$(CONFIG_JUMP_LABEL) += jump_label.o
arm64-obj-$(CONFIG_KGDB) += kgdb.o
arm64-obj-$(CONFIG_EFI) += efi.o efi-stub.o efi-entry.o
+arm64-obj-$(CONFIG_ACPI) += acpi.o

obj-y += $(arm64-obj-y) vdso/
obj-m += $(arm64-obj-m)
diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c
new file mode 100644
index 0000000..c62fce6
--- /dev/null
+++ b/arch/arm64/kernel/acpi.c
@@ -0,0 +1,76 @@
+/*
+ * ARM64 Specific Low-Level ACPI Boot Support
+ *
+ * Copyright (C) 2013-2014, Linaro Ltd.
+ * Author: Al Stone <al.stone@xxxxxxxxxx>
+ * Author: Graeme Gregory <graeme.gregory@xxxxxxxxxx>
+ * Author: Hanjun Guo <hanjun.guo@xxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/init.h>
+#include <linux/acpi.h>
+#include <linux/cpumask.h>
+#include <linux/memblock.h>
+#include <linux/irq.h>
+#include <linux/irqdomain.h>
+#include <linux/bootmem.h>
+#include <linux/smp.h>
+
+/*
+ * We never plan to use RSDT on arm/arm64 as its deprecated in spec but this
+ * variable is still required by the ACPI core
+ */
+u32 acpi_rsdt_forced;

This looks like yet another stray variable not used anywhere including
core ACPI

+
+int acpi_noirq; /* skip ACPI IRQ initialization */
+int acpi_strict;
+int acpi_disabled;
+EXPORT_SYMBOL(acpi_disabled);
+
+int acpi_pci_disabled; /* skip ACPI PCI scan and IRQ initialization */
+EXPORT_SYMBOL(acpi_pci_disabled);
+
+/*
+ * __acpi_map_table() will be called before page_init(), so early_ioremap()
+ * or early_memremap() should be called here to for ACPI table mapping.
+ */
+char *__init __acpi_map_table(unsigned long phys, unsigned long size)
+{
+ if (!phys || !size)
+ return NULL;
+
+ return early_memremap(phys, size);
+}
+
+void __init __acpi_unmap_table(char *map, unsigned long size)
+{
+ if (!map || !size)
+ return;
+
+ early_iounmap(map, size);

Why not early_memunmap for consistency ?
Also now there's generic implementation of early mappings does it make
sense to move this also to acpi core ?

Regards,
Sudeep


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