[PATCH V6 08/21] RISC-V: Add ACPI initialization in setup_arch()

Sunil V L
2023-05-15T05:52:53Z

Initialize the ACPI core for RISC-V during boot.

ACPI tables and interpreter are initialized based on
the information passed from the firmware and the value of
the kernel parameter 'acpi'.

With ACPI support added for RISC-V, the kernel parameter 'acpi'
is also supported on RISC-V. Hence, update the documentation.

Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
---
.../admin-guide/kernel-parameters.txt | 8 +-
arch/riscv/kernel/acpi.c | 126 ++++++++++++++++++
arch/riscv/kernel/setup.c | 5 +
3 files changed, 135 insertions(+), 4 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 9e5bab29685f..d910fba25f2c 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -1,17 +1,17 @@
- acpi= [HW,ACPI,X86,ARM64]
+ acpi= [HW,ACPI,X86,ARM64,RISCV64]
Advanced Configuration and Power Interface
Format: { force | on | off | strict | noirq | rsdt |
copy_dsdt }
force -- enable ACPI if default was off
- on -- enable ACPI but allow fallback to DT [arm64]
+ on -- enable ACPI but allow fallback to DT [arm64,riscv64]
off -- disable ACPI if default was on
noirq -- do not use ACPI for IRQ routing
strict -- Be less tolerant of platforms that are not
strictly ACPI specification compliant.
rsdt -- prefer RSDT over (default) XSDT
copy_dsdt -- copy DSDT to memory
- For ARM64, ONLY "acpi=off", "acpi=on" or "acpi=force"
- are available
+ For ARM64 and RISCV64, ONLY "acpi=off", "acpi=on" or
+ "acpi=force" are available

See also Documentation/power/runtime_pm.rst, pci=noacpi

diff --git a/arch/riscv/kernel/acpi.c b/arch/riscv/kernel/acpi.c
index 81d448c41714..7c080c8cbccf 100644
--- a/arch/riscv/kernel/acpi.c
+++ b/arch/riscv/kernel/acpi.c
@@ -16,6 +16,7 @@
#include <linux/acpi.h>
#include <linux/io.h>
#include <linux/pci.h>
+#include <linux/efi.h>

int acpi_noirq = 1; /* skip ACPI IRQ initialization */
int acpi_disabled = 1;
@@ -24,6 +25,131 @@ EXPORT_SYMBOL(acpi_disabled);
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_on __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, "on") == 0) /* prefer ACPI over DT */
+ param_acpi_on = 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);
+
+/*
+ * acpi_fadt_sanity_check() - Check FADT presence and carry out sanity
+ * checks on it
+ *
+ * Return 0 on success, <0 on failure
+ */
+static int __init acpi_fadt_sanity_check(void)
+{
+ struct acpi_table_header *table;
+ struct acpi_table_fadt *fadt;
+ acpi_status status;
+ int ret = 0;
+
+ /*
+ * FADT is required on riscv; retrieve it to check its presence
+ * and carry out revision and ACPI HW reduced compliancy tests
+ */
+ status = acpi_get_table(ACPI_SIG_FADT, 0, &table);
+ if (ACPI_FAILURE(status)) {
+ const char *msg = acpi_format_exception(status);
+
+ pr_err("Failed to get FADT table, %s\n", msg);
+ return -ENODEV;
+ }
+
+ fadt = (struct acpi_table_fadt *)table;
+
+ /*
+ * The revision in the table header is the FADT's Major revision. The
+ * FADT also has a minor revision, which is stored in the FADT itself.
+ *
+ * TODO: Currently, we check for 6.5 as the minimum version to check
+ * for HW_REDUCED flag. However, once RISC-V updates are released in
+ * the ACPI spec, we need to update this check for exact minor revision
+ */
+ if (table->revision < 6 || (table->revision == 6 && fadt->minor_revision < 5))
+ pr_err(FW_BUG "Unsupported FADT revision %d.%d, should be 6.5+\n",
+ table->revision, fadt->minor_revision);
+
+ if (!(fadt->flags & ACPI_FADT_HW_REDUCED)) {
+ pr_err("FADT not ACPI hardware reduced compliant\n");
+ ret = -EINVAL;
+ }
+
+ /*
+ * acpi_get_table() creates FADT table mapping that
+ * should be released after parsing and before resuming boot
+ */
+ acpi_put_table(table);
+ return ret;
+}
+
+/*
+ * acpi_boot_table_init() called from setup_arch(), always.
+ * 1. find RSDP and get its address, and then find XSDT
+ * 2. extract all tables and checksums them all
+ * 3. check ACPI FADT HW reduced flag
+ *
+ * We can parse ACPI boot-time tables such as MADT after
+ * this function is called.
+ *
+ * On return ACPI is enabled if either:
+ *
+ * - ACPI tables are initialized and sanity checks passed
+ * - acpi=force was passed in the command line and ACPI was not disabled
+ * explicitly through acpi=off command line parameter
+ *
+ * ACPI is disabled on function return otherwise
+ */
+void __init acpi_boot_table_init(void)
+{
+ /*
+ * Enable ACPI instead of device tree unless
+ * - ACPI has been disabled explicitly (acpi=off), or
+ * - firmware has not populated ACPI ptr in EFI system table
+ * and ACPI has not been [force] enabled (acpi=on|force)
+ */
+ if (param_acpi_off ||
+ (!param_acpi_on && !param_acpi_force &&
+ efi.acpi20 == EFI_INVALID_TABLE_ADDR))
+ return;
+
+ /*
+ * ACPI is disabled at this point. Enable it in order to parse
+ * the ACPI tables and carry out sanity checks
+ */
+ enable_acpi();
+
+ /*
+ * If ACPI tables are initialized and FADT sanity checks passed,
+ * leave ACPI enabled and carry on booting; otherwise disable ACPI
+ * on initialization error.
+ * If acpi=force was passed on the command line it forces ACPI
+ * to be enabled even if its initialization failed.
+ */
+ if (acpi_table_init() || acpi_fadt_sanity_check()) {
+ pr_err("Failed to init ACPI tables\n");
+ if (!param_acpi_force)
+ disable_acpi();
+ }
+}
+
/*
* __acpi_map_table() will be called before paging_init(), so early_ioremap()
* or early_memremap() should be called here to for ACPI table mapping.
diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c
index 9fb839074e16..45df7cc88b19 100644
--- a/arch/riscv/kernel/setup.c
+++ b/arch/riscv/kernel/setup.c
@@ -8,6 +8,7 @@
* Nick Kossifidis <mick@ics.forth.gr>
*/

+#include <linux/acpi.h>
#include <linux/cpu.h>
#include <linux/init.h>
#include <linux/mm.h>
@@ -276,6 +277,10 @@ void __init setup_arch(char **cmdline_p)

efi_init();
paging_init();
+
+ /* Parse the ACPI tables for possible boot-time configuration */
+ acpi_boot_table_init();
+
#if IS_ENABLED(CONFIG_BUILTIN_DTB)
unflatten_and_copy_device_tree();
#else
--
2.34.1