On Thu, Jun 09, 2016 at 05:23:28PM -0500, Jeremy Linton wrote:
> From: Mark Salter <msalter@xxxxxxxxxx>
>
> In the case of ACPI, the PMU IRQ information is contained in the
> MADT table. Also, since the PMU does not exist as a device in the
> ACPI DSDT table, it is necessary to create a platform device so
> that the appropriate driver probing is triggered.
>
> Signed-off-by: Mark Salter <msalter@xxxxxxxxxx>
> Signed-off-by: Jeremy Linton <jeremy.linton@xxxxxxx>
> ---
>
> NOTE: Much of the code in pmu_acpi_init() is replaced in a later version
> of this patch. The later version of the patch cleans up some of the
> possible style/error handling issues that have been pointed out with
> this version.
>
> arch/arm64/kernel/smp.c | 5 +++
> drivers/perf/Kconfig | 4 ++
> drivers/perf/Makefile | 1 +
> drivers/perf/arm_pmu_acpi.c | 97 ++++++++++++++++++++++++++++++++++++++++++++
> include/linux/perf/arm_pmu.h | 7 ++++
> 5 files changed, 114 insertions(+)
> create mode 100644 drivers/perf/arm_pmu_acpi.c
>
> diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
> index 678e084..5c96d23 100644
> --- a/arch/arm64/kernel/smp.c
> +++ b/arch/arm64/kernel/smp.c
> @@ -37,6 +37,7 @@
> #include <linux/completion.h>
> #include <linux/of.h>
> #include <linux/irq_work.h>
> +#include <linux/perf/arm_pmu.h>
>
> #include <asm/alternative.h>
> #include <asm/atomic.h>
> @@ -540,6 +541,7 @@ acpi_map_gic_cpu_interface(struct acpi_madt_generic_interrupt *processor)
> return;
> }
> bootcpu_valid = true;
> + arm_pmu_parse_acpi(0, processor);
> return;
> }
>
> @@ -560,6 +562,9 @@ acpi_map_gic_cpu_interface(struct acpi_madt_generic_interrupt *processor)
> */
> acpi_set_mailbox_entry(cpu_count, processor);
>
> + /* get PMU irq info */
> + arm_pmu_parse_acpi(cpu_count, processor);
> +
Nit: the outer functions are now misnomers, since this has nothing to do
with the GIC. It feels like acpi_parse_gic_cpu_interface could use some
slight restructuring so that the MADT parsing looks less confused.
> diff --git a/drivers/perf/Makefile b/drivers/perf/Makefile
> index acd2397..fd8090d 100644
> --- a/drivers/perf/Makefile
> +++ b/drivers/perf/Makefile
> @@ -1 +1,2 @@
> obj-$(CONFIG_ARM_PMU) += arm_pmu.o
> +obj-$(CONFIG_ARM_PMU_ACPI) += arm_pmu_acpi.o
> diff --git a/drivers/perf/arm_pmu_acpi.c b/drivers/perf/arm_pmu_acpi.c
> new file mode 100644
> index 0000000..98c452d
> --- /dev/null
> +++ b/drivers/perf/arm_pmu_acpi.c
> @@ -0,0 +1,97 @@
> +/*
> + * PMU support
> + *
> + * Copyright (C) 2015 Red Hat Inc.
> + * Author: Mark Salter <msalter@xxxxxxxxxx>
> + *
> + * This work is licensed under the terms of the GNU GPL, version 2. See
> + * the COPYING file in the top-level directory.
> + *
> + */
> +
> +#include <linux/perf/arm_pmu.h>
> +#include <linux/platform_device.h>
> +#include <linux/acpi.h>
> +#include <linux/irq.h>
> +#include <linux/irqdesc.h>
> +
> +#define PMU_PDEV_NAME "armv8-pmu"
Stick this in include/linux/perf/arm_pmu.h where we can use it in the driver
code too?
> +
> +struct pmu_irq {
> + int gsi;
> + int trigger;
> +};
> +
> +static struct pmu_irq pmu_irqs[NR_CPUS] __initdata;
> +
> +void __init arm_pmu_parse_acpi(int cpu, struct acpi_madt_generic_interrupt *gic)
> +{
> + pmu_irqs[cpu].gsi = gic->performance_interrupt;
> + if (gic->flags & ACPI_MADT_PERFORMANCE_IRQ_MODE)
> + pmu_irqs[cpu].trigger = ACPI_EDGE_SENSITIVE;
> + else
> + pmu_irqs[cpu].trigger = ACPI_LEVEL_SENSITIVE;
> +}
> +
> +static int __init pmu_acpi_init(void)
> +{
> + struct platform_device *pdev;
> + struct pmu_irq *pirq = pmu_irqs;
> + struct resource *res, *r;
> + int err = -ENOMEM;
> + int i, count, irq;
> +
> + if (acpi_disabled)
> + return 0;
> +
> + /* Must have irq for boot boot cpu, at least */
boot boot
> + if (pirq->gsi == 0)
> + return -EINVAL;
> +
> + irq = acpi_register_gsi(NULL, pirq->gsi, pirq->trigger,
> + ACPI_ACTIVE_HIGH);
This is quite tricky to read, thanks to the aliasing of pirq and
pmu_irqs[0]. Why is it necessary to register the first gsi separately,
rather than just register it later in the loop with all the other
interrupts?
Will
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