Commit 54971e43 authored by Lorenzo Pieralisi's avatar Lorenzo Pieralisi Committed by Will Deacon
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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: default avatarLorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: default avatarHanjun Guo <hanjun.guo@linaro.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Hanjun Guo <hanjun.guo@linaro.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
parent d9895571

arch/arm64/kernel/acpi.c

+59 −36
Original line number Diff line number Diff line
@@ -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;



	/*

	 * 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.

	 * FADT is required on arm64; retrieve it to check its presence

	 * and carry out revision and ACPI HW reduced compliancy tests

	 */

	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;

	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;



	/*

		 * 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.

	 * 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.

	 */

		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 @@ disable_acpi: 
 *	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");

	}

}

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