From 54971e43b9d6cb37366d2da64cc5a2d8f8102bc4 Mon Sep 17 00:00:00 2001 From: Lorenzo Pieralisi Date: Wed, 25 Mar 2015 15:13:56 +0000 Subject: [PATCH] ARM64: kernel: acpi: refactor ACPI tables init and checks Current ACPI init code on ARM64 relies on acpi_table_parse() API to check if the FADT is present and to carry out sanity checks on that. The handler passed to the acpi_table_parse() function and used to carry out the parsing on the requested table returns a value that is ignored by the acpi_table_parse() function, so it is not possible to propagate errors back to the acpi_table_parse() caller through the handler. This forces ARM64 ACPI init code to have disable_acpi() calls scattered all over the place that makes code unwieldy and not easy to follow. This patch refactors the ARM64 ACPI init code, by creating a self-contained function (ie acpi_fadt_sanity_check()) that carries out the required checks on FADT and returns an adequate return value to the caller. This allows creating a common error path that disables ACPI and makes code more readable and easy to parse and change were further checks FADT to be added in the future. Signed-off-by: Lorenzo Pieralisi Reviewed-by: Hanjun Guo Cc: Will Deacon Cc: Hanjun Guo Cc: Catalin Marinas Cc: Rafael J. Wysocki Signed-off-by: Will Deacon --- arch/arm64/kernel/acpi.c | 95 +++++++++++++++++++++++++--------------- 1 file changed, 59 insertions(+), 36 deletions(-) diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c index a70f7141c0f6..172b7c9f6881 100644 --- a/arch/arm64/kernel/acpi.c +++ b/arch/arm64/kernel/acpi.c @@ -218,43 +218,60 @@ void __init acpi_init_cpus(void) pr_info("%d CPUs enabled, %d CPUs total\n", enabled_cpus, total_cpus); } -static int __init acpi_parse_fadt(struct acpi_table_header *table) +/* + * 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_fadt *fadt = (struct acpi_table_fadt *)table; + struct acpi_table_header *table; + struct acpi_table_fadt *fadt; + acpi_status status; + acpi_size tbl_size; + int ret = 0; + + /* + * FADT is required on arm64; retrieve it to check its presence + * and carry out revision and ACPI HW reduced compliancy tests + */ + status = acpi_get_table_with_size(ACPI_SIG_FADT, 0, &table, &tbl_size); + 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; /* * 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. + * boot protocol configuration data. */ - if (table->revision > 5 || - (table->revision == 5 && fadt->minor_revision >= 1)) { - if (!acpi_gbl_reduced_hardware) { - pr_err("Not hardware reduced ACPI mode, will not be supported\n"); - goto disable_acpi; - } - - /* - * ACPI 5.1 only has two explicit methods to boot up SMP, - * PSCI and Parking protocol, but the Parking protocol is - * only specified for ARMv7 now, so make PSCI as the only - * way for the SMP boot protocol before some updates for - * the Parking protocol spec. - */ - if (acpi_psci_present()) - return 0; - - pr_warn("No PSCI support, will not bring up secondary CPUs\n"); - return -EOPNOTSUPP; + if (table->revision < 5 || + (table->revision == 5 && fadt->minor_revision < 1)) { + pr_err("Unsupported FADT revision %d.%d, should be 5.1+\n", + table->revision, fadt->minor_revision); + ret = -EINVAL; + goto out; } - pr_warn("Unsupported FADT revision %d.%d, should be 5.1+, will disable ACPI\n", - table->revision, fadt->minor_revision); + if (!(fadt->flags & ACPI_FADT_HW_REDUCED)) { + pr_err("FADT not ACPI hardware reduced compliant\n"); + ret = -EINVAL; + } -disable_acpi: - disable_acpi(); - return -EINVAL; +out: + /* + * acpi_get_table_with_size() creates FADT table mapping that + * should be released after parsing and before resuming boot + */ + early_acpi_os_unmap_memory(table, tbl_size); + return ret; } /* @@ -262,9 +279,13 @@ static int __init acpi_parse_fadt(struct acpi_table_header *table) * 1. find RSDP and get its address, and then find XSDT * 2. extract all tables and checksums them all * 3. check ACPI FADT revision + * 4. check ACPI FADT HW reduced flag * * We can parse ACPI boot-time tables such as MADT after * this function is called. + * + * ACPI is enabled on return if ACPI tables initialized and sanity checks + * passed, disabled otherwise */ void __init acpi_boot_table_init(void) { @@ -278,18 +299,20 @@ void __init acpi_boot_table_init(void) (!param_acpi_force && of_scan_flat_dt(dt_scan_depth1_nodes, NULL))) return; + /* + * ACPI is disabled at this point. Enable it in order to parse + * the ACPI tables and carry out sanity checks + */ enable_acpi(); - /* Initialize the ACPI boot-time table parser. */ - if (acpi_table_init()) { - disable_acpi(); - return; - } - - if (acpi_table_parse(ACPI_SIG_FADT, acpi_parse_fadt)) { - /* disable ACPI if no FADT is found */ + /* + * 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_table_init() || acpi_fadt_sanity_check()) { + pr_err("Failed to init ACPI tables\n"); disable_acpi(); - pr_err("Can't find FADT\n"); } } -- 2.45.2