[PATCH V2 18/21] RISC-V: Add ACPI initialization in setup_arch()

Sunil V L
2023-02-16T18:23:40Z

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'.

Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
arch/riscv/kernel/acpi.c | 113 ++++++++++++++++++++++++++++++++++++++
arch/riscv/kernel/setup.c | 25 ++++++---
2 files changed, 130 insertions(+), 8 deletions(-)

diff --git a/arch/riscv/kernel/acpi.c b/arch/riscv/kernel/acpi.c
index 13b26c87c136..35e7b24a30c8 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;
@@ -26,6 +27,118 @@ EXPORT_SYMBOL(acpi_pci_disabled);

static unsigned int intc_count;
static struct acpi_madt_rintc cpu_madt_rintc[NR_CPUS];
+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;
+
+ 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();
+ }
+}

static int acpi_parse_madt_rintc(union acpi_subtable_headers *header, const unsigned long end)
{
diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c
index 4335f08ffaf2..c2ee7f4427a1 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/init.h>
#include <linux/mm.h>
#include <linux/memblock.h>
@@ -276,14 +277,22 @@ void __init setup_arch(char **cmdline_p)

efi_init();
paging_init();
-#if IS_ENABLED(CONFIG_BUILTIN_DTB)
- unflatten_and_copy_device_tree();
-#else
- if (early_init_dt_verify(__va(XIP_FIXUP(dtb_early_pa))))
- unflatten_device_tree();
- else
- pr_err("No DTB found in kernel mappings\n");
-#endif
+
+ /* Parse the ACPI tables for possible boot-time configuration */
+ acpi_boot_table_init();
+ if (acpi_disabled) {
+ if (IS_ENABLED(CONFIG_BUILTIN_DTB)) {
+ unflatten_and_copy_device_tree();
+ } else {
+ if (early_init_dt_verify(__va(XIP_FIXUP(dtb_early_pa))))
+ unflatten_device_tree();
+ else
+ pr_err("No DTB found in kernel mappings\n");
+ }
+ } else {
+ early_init_dt_verify(__va(XIP_FIXUP(dtb_early_pa)));
+ }
+
early_init_fdt_scan_reserved_mem();
misc_mem_init();

--
2.34.1