Re: [PATCH v3 13/17] ARM64 / ACPI: Add GICv2 specific ACPI boot support

Grant Likely
2014-09-11T11:48:40Z

On Tue, 02 Sep 2014 13:48:37 +0200, Tomasz Nowicki <tomasz.nowicki@linaro.org> wrote:
> On 01.09.2014 19:35, Marc Zyngier wrote:
> > On 01/09/14 15:57, Hanjun Guo wrote:
> >> From: Tomasz Nowicki <tomasz.nowicki@linaro.org>
> >>
> >> ACPI kernel uses MADT table for proper GIC initialization. It needs to
> >> parse GIC related subtables, collect CPU interface and distributor
> >> addresses and call driver initialization function (which is hardware
> >> abstraction agnostic). In a similar way, FDT initialize GICv1/2.
> >>
> >> NOTE: This commit allow to initialize GICv1/2 only.
> >
> > I cannot help but notice that there is no support for KVM here. It'd be
> > good to add a note to that effect, so that people do not expect
> > virtualization support to be working when booting with ACPI.
>
> yes, it is worth mentioning!
>
> >
> >> Signed-off-by: Tomasz Nowicki <tomasz.nowicki@linaro.org>
> >> Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>
> >> ---
> >> arch/arm64/include/asm/acpi.h | 2 -
> >> arch/arm64/kernel/acpi.c | 23 +++++++
> >> arch/arm64/kernel/irq.c | 5 ++
> >> drivers/irqchip/irq-gic.c | 114 ++++++++++++++++++++++++++++++++++
> >> include/linux/irqchip/arm-gic-acpi.h | 33 ++++++++++
> >> 5 files changed, 175 insertions(+), 2 deletions(-)
> >> create mode 100644 include/linux/irqchip/arm-gic-acpi.h
> >>
> >> diff --git a/arch/arm64/include/asm/acpi.h b/arch/arm64/include/asm/acpi.h
> >> index a867467..5d2ab63 100644
> >> --- a/arch/arm64/include/asm/acpi.h
> >> +++ b/arch/arm64/include/asm/acpi.h
> >> @@ -97,8 +97,6 @@ void __init acpi_smp_init_cpus(void);
> >> extern int (*acpi_suspend_lowlevel)(void);
> >> #define acpi_wakeup_address 0
> >>
> >> -#define ACPI_MAX_GIC_CPU_INTERFACE_ENTRIES 65535
> >> -
> >> #else
> >>
> >> static inline bool acpi_psci_present(void) { return false; }
> >> diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c
> >> index 354b912..b3b82b0 100644
> >> --- a/arch/arm64/kernel/acpi.c
> >> +++ b/arch/arm64/kernel/acpi.c
> >> @@ -23,6 +23,7 @@
> >> #include <linux/irqdomain.h>
> >> #include <linux/bootmem.h>
> >> #include <linux/smp.h>
> >> +#include <linux/irqchip/arm-gic-acpi.h>
> >>
> >> #include <asm/cputype.h>
> >> #include <asm/cpu_ops.h>
> >> @@ -313,6 +314,28 @@ void __init acpi_boot_table_init(void)
> >> pr_err("Can't find FADT or error happened during parsing FADT\n");
> >> }
> >>
> >> +void __init acpi_gic_init(void)
> >> +{
> >> + struct acpi_table_header *table;
> >> + acpi_status status;
> >> + acpi_size tbl_size;
> >> + int err;
> >> +
> >> + status = acpi_get_table_with_size(ACPI_SIG_MADT, 0, &table, &tbl_size);
> >> + if (ACPI_FAILURE(status)) {
> >> + const char *msg = acpi_format_exception(status);
> >> +
> >> + pr_err("Failed to get MADT table, %s\n", msg);
> >> + return;
> >> + }
> >> +
> >> + err = gic_v2_acpi_init(table);
> >> + if (err)
> >> + pr_err("Failed to initialize GIC IRQ controller");
> >
> > What will happen when you get to implement GICv3 support? Another entry
> > like this? Why isn't this entirely contained in the GIC driver? Do I
> > sound like a stuck record?
>
> There will be another call to GICv3 init:
> [...]
> err = gic_v3_acpi_init(table);
> if (err)
> err = gic_v2_acpi_init(table);
> if (err)
> pr_err("Failed to initialize GIC IRQ controller");
> [...]
> This is the main reason I put common code here.
>
> >
> >> +
> >> + early_acpi_os_unmap_memory((char *)table, tbl_size);
> >> +}
> >> +
> >> /*
> >> * acpi_suspend_lowlevel() - save kernel state and suspend.
> >> *
> >> diff --git a/arch/arm64/kernel/irq.c b/arch/arm64/kernel/irq.c
> >> index 0f08dfd..c074d60 100644
> >> --- a/arch/arm64/kernel/irq.c
> >> +++ b/arch/arm64/kernel/irq.c
> >> @@ -28,6 +28,7 @@
> >> #include <linux/irqchip.h>
> >> #include <linux/seq_file.h>
> >> #include <linux/ratelimit.h>
> >> +#include <linux/irqchip/arm-gic-acpi.h>
> >>
> >> unsigned long irq_err_count;
> >>
> >> @@ -78,6 +79,10 @@ void __init set_handle_irq(void (*handle_irq)(struct pt_regs *))
> >> void __init init_IRQ(void)
> >> {
> >> irqchip_init();
> >> +
> >> + if (!handle_arch_irq)
> >> + acpi_gic_init();
> >> +
> >
> > Why isn't this called from irqchip_init? It would seem like the logical
> > spot to probe an interrupt controller.
>
> irqchip.c is OF dependent, I want to decouple these from the very
> beginning.

It doesn't have to be that way, but given that ARM64 is the only
platform in the foreseeable future that will use ACPI irq setup, it
doesn't make sense to put it in there.

g.