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    SubjectRe: [PATCH 3/4] arm_pmu: acpi: spe: Add initial MADT/SPE probing
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    On 26/03/2019 22:39, Jeremy Linton wrote:
    > ACPI 6.3 adds additional fields to the MADT GICC
    > structure to describe SPE PPI's. We pick these out
    > of the cached reference to the madt_gicc structure
    > similarly to the core PMU code. We then create a platform
    > device referring to the IRQ and let the user/module loader
    > decide whether to load the SPE driver.
    >
    > Signed-off-by: Jeremy Linton <jeremy.linton@arm.com>
    > ---
    > arch/arm64/include/asm/acpi.h | 3 ++
    > drivers/perf/arm_pmu_acpi.c | 69 +++++++++++++++++++++++++++++++++++
    > 2 files changed, 72 insertions(+)
    >
    > diff --git a/arch/arm64/include/asm/acpi.h b/arch/arm64/include/asm/acpi.h
    > index 7628efbe6c12..d10399b9f998 100644
    > --- a/arch/arm64/include/asm/acpi.h
    > +++ b/arch/arm64/include/asm/acpi.h
    > @@ -41,6 +41,9 @@
    > (!(entry) || (entry)->header.length < ACPI_MADT_GICC_MIN_LENGTH || \
    > (unsigned long)(entry) + (entry)->header.length > (end))
    >
    > +#define ACPI_MADT_GICC_SPE (ACPI_OFFSET(struct acpi_madt_generic_interrupt, \
    > + spe_interrupt) + sizeof(u16))
    > +
    > /* Basic configuration for ACPI */
    > #ifdef CONFIG_ACPI
    > pgprot_t __acpi_get_mem_attribute(phys_addr_t addr);
    > diff --git a/drivers/perf/arm_pmu_acpi.c b/drivers/perf/arm_pmu_acpi.c
    > index 0f197516d708..a2418108eab2 100644
    > --- a/drivers/perf/arm_pmu_acpi.c
    > +++ b/drivers/perf/arm_pmu_acpi.c
    > @@ -74,6 +74,73 @@ static void arm_pmu_acpi_unregister_irq(int cpu)
    > acpi_unregister_gsi(gsi);
    > }
    >
    > +static struct resource spe_resources[] = {
    > + {
    > + /* irq */
    > + .flags = IORESOURCE_IRQ,
    > + }
    > +};
    > +
    > +static struct platform_device spe_dev = {
    > + .name = "arm,spe-v1",
    > + .id = -1,
    > + .resource = spe_resources,
    > + .num_resources = ARRAY_SIZE(spe_resources)
    > +};
    > +
    > +/*
    > + * For lack of a better place,

    It seems that the kernel Image size can now increase due to this part of
    SPE support even if ARM_SPE_PMU config is disabled.

    And I don't even think that ARM_SPE_PMU depends on ARM_PMU (which
    ARM_PMU_ACPI depends on).

    Thanks,
    John

    hook the normal PMU MADT walk
    > + * and create a SPE device if we detect a recent MADT with
    > + * a homogeneous PPI mapping.
    > + */
    > +static int arm_spe_acpi_parse_irqs(void)
    > +{
    > + int cpu, ret, irq;
    > + int hetid;
    > + u16 gsi = 0;
    > + bool first = true;
    > +
    > + struct acpi_madt_generic_interrupt *gicc;
    > +
    > + /*
    > + * sanity check all the GICC tables for the same interrupt number
    > + * for now we only support homogeneous ACPI/SPE machines.
    > + */
    > + for_each_possible_cpu(cpu) {
    > + gicc = acpi_cpu_get_madt_gicc(cpu);
    > +
    > + if (gicc->header.length < ACPI_MADT_GICC_SPE)
    > + return -ENODEV;
    > + if (first) {
    > + gsi = gicc->spe_interrupt;
    > + if (!gsi)
    > + return -ENODEV;
    > + hetid = find_acpi_cpu_topology_hetero_id(cpu);
    > + first = false;
    > + } else if ((gsi != gicc->spe_interrupt) ||
    > + (hetid != find_acpi_cpu_topology_hetero_id(cpu))) {
    > + pr_warn("ACPI: SPE must be homogeneous\n");
    > + return -EINVAL;
    > + }
    > + }
    > +
    > + irq = acpi_register_gsi(NULL, gsi, ACPI_LEVEL_SENSITIVE,
    > + ACPI_ACTIVE_HIGH);
    > + if (irq < 0) {
    > + pr_warn("ACPI: SPE Unable to register interrupt: %d\n", gsi);
    > + return irq;
    > + }
    > +
    > + spe_resources[0].start = irq;
    > + ret = platform_device_register(&spe_dev);
    > + if (ret < 0) {
    > + pr_warn("ACPI: SPE: Unable to register device\n");
    > + acpi_unregister_gsi(gsi);
    > + }
    > +
    > + return ret;
    > +}
    > +
    > static int arm_pmu_acpi_parse_irqs(void)
    > {
    > int irq, cpu, irq_cpu, err;
    > @@ -279,6 +346,8 @@ static int arm_pmu_acpi_init(void)
    > if (acpi_disabled)
    > return 0;
    >
    > + arm_spe_acpi_parse_irqs(); /* failures are expected */
    > +
    > ret = arm_pmu_acpi_parse_irqs();
    > if (ret)
    > return ret;
    >


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