[Xen-devel] [PATCH v2 08/41] arm/acpi : Parse FADT table and get PSCI flags

[Parth Dixit <parth.dixit@xxxxxxxxxx>]

There are two flags: PSCI_COMPLIANT and PSCI_USE_HVC. When set,
the former signals to the OS that the hardware is PSCI compliant.
The latter selects the appropriate conduit for PSCI calls by
toggling between Hypervisor Calls (HVC) and Secure Monitor Calls
(SMC).

FADT table contains such information, parse FADT to get the flags
for furture usage. At the same time, only ACPI 5.1 or higher verison
supports PSCI, and FADT Major.Minor version was introduced in ACPI
5.1, so we will check the version and only parse FADT table with
version >= 5.1.

If firmware provides ACPI tables with ACPI version less than 5.1,
OS will be messed up with those information, so disable ACPI if we
get an FADT table with version less that 5.1.

Modify FADT table before passing it to Dom0.
Set PSCI_COMPLIANT and PSCI_USE_HVC.

Signed-off-by: Hanjun Guo <hanjun.guo@xxxxxxxxxx>
Signed-off-by: Naresh Bhat <naresh.bhat@xxxxxxxxxx>
Signed-off-by: Parth Dixit <parth.dixit@xxxxxxxxxx>
---
 xen/arch/arm/acpi/boot.c   | 38 ++++++++++++++++++++++++++++++++++++++
 xen/arch/arm/acpi/lib.c    | 11 +++++++++++
 xen/include/asm-arm/acpi.h | 11 +++++++++++
 3 files changed, 60 insertions(+)

diff --git a/xen/arch/arm/acpi/boot.c b/xen/arch/arm/acpi/boot.c
index 8dc69d5..57eb33c 100644
--- a/xen/arch/arm/acpi/boot.c
+++ b/xen/arch/arm/acpi/boot.c
@@ -24,9 +24,40 @@
 
 #include <xen/init.h>
 #include <xen/acpi.h>
+#include <xen/errno.h>
+#include <acpi/actables.h>
+#include <xen/mm.h>
 
 #include <asm/acpi.h>
 
+static int __init acpi_parse_fadt(struct acpi_table_header *table)
+{
+    struct acpi_table_fadt *fadt = (struct acpi_table_fadt *)table;
+    u8 checksum;
+
+    /*
+     * Revision in table header is the FADT Major revision, and there
+     * is a minor revision of FADT which was introduced by ACPI 5.1,
+     * we only deal with ACPI 5.1 or newer revision to get GIC and SMP
+     * boot protocol configuration data, or we will disable ACPI.
+     */
+    if ( table->revision > 5 ||
+            ( table->revision == 5 && fadt->minor_revision >= 1 ) )
+    {
+        fadt->arm_boot_flags |= ( ACPI_FADT_PSCI_COMPLIANT | 
ACPI_FADT_PSCI_USE_HVC );
+        checksum = acpi_tb_checksum(ACPI_CAST_PTR(u8, fadt), 
fadt->header.length);
+        fadt->header.checksum -= checksum;
+        clean_dcache_va_range(fadt, sizeof(struct acpi_table_fadt));
+        return 0;
+    }
+
+    printk("Unsupported FADT revision %d.%d, should be 5.1+, will disable 
ACPI\n",
+            table->revision, fadt->minor_revision);
+    disable_acpi();
+
+    return -EINVAL;
+}
+
 /*
  * acpi_boot_table_init() called from setup_arch(), always.
  *      1. find RSDP and get its address, and then find XSDT
@@ -51,6 +82,13 @@ int __init acpi_boot_table_init(void)
         return error;
     }
 
+    if ( acpi_table_parse(ACPI_SIG_FADT, acpi_parse_fadt) )
+    {
+        /* disable ACPI if no FADT is found */
+        disable_acpi();
+        printk("Can't find FADT\n");
+    }
+
     return 0;
 }
 
diff --git a/xen/arch/arm/acpi/lib.c b/xen/arch/arm/acpi/lib.c
index 650beed..fd9bfa4 100644
--- a/xen/arch/arm/acpi/lib.c
+++ b/xen/arch/arm/acpi/lib.c
@@ -6,3 +6,14 @@ acpi_os_map_iomem(acpi_physical_address phys, acpi_size size)
 {
     return __va(phys);
 }
+/* 1 to indicate PSCI 0.2+ is implemented */
+inline bool_t acpi_psci_present(void)
+{
+    return acpi_gbl_FADT.arm_boot_flags & ACPI_FADT_PSCI_COMPLIANT;
+}
+
+/* 1 to indicate HVC is present instead of SMC as the PSCI conduit */
+inline bool_t acpi_psci_hvc_present(void)
+{
+    return acpi_gbl_FADT.arm_boot_flags & ACPI_FADT_PSCI_USE_HVC;
+}
diff --git a/xen/include/asm-arm/acpi.h b/xen/include/asm-arm/acpi.h
index f771056..058f343 100644
--- a/xen/include/asm-arm/acpi.h
+++ b/xen/include/asm-arm/acpi.h
@@ -29,6 +29,17 @@
 #define COMPILER_DEPENDENT_UINT64  unsigned long long
 
 extern bool_t acpi_disabled;
+
+#ifdef CONFIG_ACPI
+/* 1 to indicate PSCI 0.2+ is implemented */
+bool_t acpi_psci_present(void);
+/* 1 to indicate HVC is present instead of SMC as the PSCI conduit */
+bool_t acpi_psci_hvc_present(void);
+#else
+static inline bool_t acpi_psci_present(void) { return false; }
+static inline bool_t acpi_psci_hvc_present(void) {return false; }
+#endif /* CONFIG_ACPI */
+
 /* Basic configuration for ACPI */
 static inline void disable_acpi(void)
 {
-- 
1.9.1


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