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SubjectRe: [PATCH 06/19] ARM64 / ACPI: Parse FADT table to get PSCI flags for PSCI init


On 24/07/14 14:00, Hanjun Guo wrote:
> 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 PSCI init. Since ACPI 5.1 doesn't support self defined PSCI
> function IDs, which means that only PSCI 0.2+ is supported in ACPI.
>
> 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 and have no way to
> bring up secondery CPUs, so disable ACPI if we get an FADT table
> with version less that 5.1.
>
> Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>
> Signed-off-by: Graeme Gregory <graeme.gregory@linaro.org>
> ---
> arch/arm64/include/asm/acpi.h | 2 +
> arch/arm64/kernel/acpi.c | 50 ++++++++++++++++++++++
> arch/arm64/kernel/psci.c | 95 +++++++++++++++++++++++++++++------------
> arch/arm64/kernel/setup.c | 2 +
> 4 files changed, 121 insertions(+), 28 deletions(-)
>
> diff --git a/arch/arm64/include/asm/acpi.h b/arch/arm64/include/asm/acpi.h
> index 44b617f..67dac90 100644
> --- a/arch/arm64/include/asm/acpi.h
> +++ b/arch/arm64/include/asm/acpi.h
> @@ -18,6 +18,8 @@ extern int acpi_disabled;
> extern int acpi_noirq;
> extern int acpi_pci_disabled;
> extern int acpi_strict;
> +extern int acpi_psci_present;
> +extern int acpi_psci_use_hvc;
>
> static inline void disable_acpi(void)
> {
> diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c
> index f5a10b5..374926f 100644
> --- a/arch/arm64/kernel/acpi.c
> +++ b/arch/arm64/kernel/acpi.c
> @@ -11,6 +11,8 @@
> * published by the Free Software Foundation.
> */
>
> +#define pr_fmt(fmt) "ACPI: " fmt
> +
> #include <linux/init.h>
> #include <linux/acpi.h>
> #include <linux/cpumask.h>
> @@ -34,6 +36,12 @@ EXPORT_SYMBOL(acpi_disabled);
> int acpi_pci_disabled; /* skip ACPI PCI scan and IRQ initialization */
> EXPORT_SYMBOL(acpi_pci_disabled);
>
> +/* 1 to indicate PSCI is implemented */
> +int acpi_psci_present;
> +
> +/* 1 to indicate HVC must be used instead of SMC as the PSCI conduit */
> +int acpi_psci_use_hvc;
> +

These can be boolean but can be removed IMO, see below.

> /*
> * __acpi_map_table() will be called before page_init(), so early_ioremap()
> * or early_memremap() should be called here to for ACPI table mapping.
> @@ -54,6 +62,33 @@ void __init __acpi_unmap_table(char *map, unsigned long size)
> early_iounmap(map, size);
> }
>
> +static int __init acpi_parse_fadt(struct acpi_table_header *table)
> +{
> + struct acpi_table_fadt *fadt = (struct acpi_table_fadt *)table;
> +
> + /*
> + * Revision in table header is the FADT Major version,
> + * and there is a minor version of FADT which was introduced
> + * by ACPI 5.1, we only deal with ACPI 5.1 or higher version
> + * to get arm boot flags, or we will disable ACPI.
> + */
> + if (table->revision < 5 || fadt->minor_version < 1) {
> + pr_info("FADT version is %d.%d, no PSCI support, should be 5.1 or higher\n",
> + table->revision, fadt->minor_version);
> + acpi_psci_present = 0;
> + disable_acpi();
> + return -EINVAL;
> + }
> +
> + if (acpi_gbl_FADT.arm_boot_flags & ACPI_FADT_PSCI_COMPLIANT)
> + acpi_psci_present = 1;
> +
> + if (acpi_gbl_FADT.arm_boot_flags & ACPI_FADT_PSCI_USE_HVC)
> + acpi_psci_use_hvc = 1;
> +

Why not make this macros instead of global variables as I suggested in
previous version. acpi_gbl_FADT is already global and you can avoid
creating new one especially they are just used on boot/init.

Regards,
Sudeep



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