On Fri, Jun 19, 2015 at 09:46:06AM +0100, Hanjun Guo wrote:
[...]
> +
> +static int __init
> +match_gic_redist(struct acpi_subtable_header *header, const unsigned long end)
> +{
> + return 0;
> +}
> +static bool __init acpi_gic_redist_is_present(void)
> +{
> + int count;
> +
> + /* scan MADT table to find if we have redistributor entries */
> + count = acpi_table_parse_madt(ACPI_MADT_TYPE_GENERIC_REDISTRIBUTOR,
> + match_gic_redist, 0);
> +
> + /* has at least one GIC redistributor entry */
> + if (count > 0)
> + return true;
> + else
> + return false;
> +}
return count > 0;
What about systems where the redistributor data is in the GICC subtable ? Do
you treat them as GIC V2 :) ?
On a side note, having to define an empty function like match_gic_redist is
horrible.
I wonder whether it is not better to refactor map_madt_entry(), create
a MADT subtable iterator out of it and make that code generic, instead
of being forced to add these useless MADT handlers just to count
entries, it is not the first I noticed.
> +static int __init acpi_gic_version_init(void)
> +{
> + int count;
> + void __iomem *dist_base;
> + u32 reg;
> +
> + count = acpi_table_parse_madt(ACPI_MADT_TYPE_GENERIC_DISTRIBUTOR,
> + acpi_gic_parse_distributor, 0);
> +
> + if (count <= 0) {
> + pr_err("No valid GIC distributor entry exists\n");
> + return -ENODEV;
> + }
> +
> + if (gic_version >= ACPI_MADT_GIC_VERSION_RESERVED) {
> + pr_err("Invalid GIC version %d in MADT\n", gic_version);
> + return -EINVAL;
> + }
> +
> + /*
> + * when the GIC version is 0, we fallback to hardware discovery.
> + * this is also needed to keep compatiable with ACPI 5.1,
> + * which has no gic_version field in distributor structure and
> + * reserved as 0.
> + *
> + * For hardware discovery, the offset for GICv1/2 and GICv3/4 to
> + * get the GIC version is different (0xFE8 for GICv1/2 and 0xFFE8
> + * for GICv3/4), so we need to handle it separately.
> + */
> + if (gic_version == ACPI_MADT_GIC_VERSION_NONE) {
> + /* it's GICv3/v4 if redistributor is present */
> + if (acpi_gic_redist_is_present()) {
See above, IIUC you might have systems with GIC v3 where this call
would fail, and we do not want to fall back to GIC v2.
Lorenzo
> + dist_base = ioremap(dist_phy_base,
> + ACPI_GICV3_DIST_MEM_SIZE);
> + if (!dist_base)
> + return -ENOMEM;
> +
> + reg = readl_relaxed(dist_base + GICD_PIDR2) &
> + GIC_PIDR2_ARCH_MASK;
> + if (reg == GIC_PIDR2_ARCH_GICv3)
> + gic_version = ACPI_MADT_GIC_VERSION_V3;
> + else
> + gic_version = ACPI_MADT_GIC_VERSION_V4;
> +
> + iounmap(dist_base);
> + } else {
> + gic_version = ACPI_MADT_GIC_VERSION_V2;
> + }
> + }
> +
> + return 0;
> +}
> diff --git a/include/linux/irqchip/arm-gic-acpi.h b/include/linux/irqchip/arm-gic-acpi.h
> index de3419e..13bc676 100644
> --- a/include/linux/irqchip/arm-gic-acpi.h
> +++ b/include/linux/irqchip/arm-gic-acpi.h
> @@ -19,6 +19,7 @@
> */
> #define ACPI_GICV2_DIST_MEM_SIZE (SZ_4K)
> #define ACPI_GIC_CPU_IF_MEM_SIZE (SZ_8K)
> +#define ACPI_GICV3_DIST_MEM_SIZE (SZ_64K)
>
> struct acpi_table_header;
>
> --
> 1.9.1
>
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