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

From: [email-masked] (Tomasz Nowicki)
Date: Wed, 03 Sep 2014 11:26:14 +0200

On 02.09.2014 15:02, Marc Zyngier wrote:
> On 02/09/14 12:48, Tomasz Nowicki wrote:
>> On 01.09.2014 19:35, Marc Zyngier wrote:
>>> On 01/09/14 15:57, Hanjun Guo wrote:
>>>> From: Tomasz Nowicki <[email-masked]>
>>>>
>>>> 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 <[email-masked]>
>>>> Signed-off-by: Hanjun Guo <[email-masked]>
>>>> ---
>>>>    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.
>
> No. irqchip.c is not OF dependent, it is just that DT is the only thing
> we support so far. I don't think duplicating the kernel infrastructure
> "because we're different" is the right way.
>
> There is no reason for your probing structure to be artificially
> different (you're parsing the same information, at the same time). Just
> put in place a similar probing mechanism, and this will look a lot better.
>
>>>
>>>>       if (!handle_arch_irq)
>>>>               panic("No interrupt controller found.");
>>>>    }
>>>> diff --git a/drivers/irqchip/irq-gic.c b/drivers/irqchip/irq-gic.c
>>>> index 4b959e6..85cbf43 100644
>>>> --- a/drivers/irqchip/irq-gic.c
>>>> +++ b/drivers/irqchip/irq-gic.c
>>>> @@ -33,12 +33,14 @@
>>>>    #include <linux/of.h>
>>>>    #include <linux/of_address.h>
>>>>    #include <linux/of_irq.h>
>>>> +#include <linux/acpi.h>
>>>>    #include <linux/irqdomain.h>
>>>>    #include <linux/interrupt.h>
>>>>    #include <linux/percpu.h>
>>>>    #include <linux/slab.h>
>>>>    #include <linux/irqchip/chained_irq.h>
>>>>    #include <linux/irqchip/arm-gic.h>
>>>> +#include <linux/irqchip/arm-gic-acpi.h>
>>>>
>>>>    #include <asm/cputype.h>
>>>>    #include <asm/irq.h>
>>>> @@ -1029,3 +1031,115 @@ IRQCHIP_DECLARE(msm_8660_qgic, "qcom,msm-8660-qgic", gic_of_init);
>>>>    IRQCHIP_DECLARE(msm_qgic2, "qcom,msm-qgic2", gic_of_init);
>>>>
>>>>    #endif
>>>> +
>>>> +#ifdef CONFIG_ACPI
>>>> +static u64 dist_phy_base, cpu_phy_base = ULONG_MAX;
>>>
>>> Please use phys_addr_t for physical addresses. The use of ULONG_MAX
>>> looks dodgy. Please have a proper symbol to flag the fact that it hasn't
>>> been assigned yet.
>> Sure, will do.
>>
>>>
>>>> +
>>>> +static int __init
>>>> +gic_acpi_parse_madt_cpu(struct acpi_subtable_header *header,
>>>> +                    const unsigned long end)
>>>> +{
>>>> +    struct acpi_madt_generic_interrupt *processor;
>>>> +    u64 gic_cpu_base;
>>>
>>> phys_addr_t
>>>
>>>> +    processor = (struct acpi_madt_generic_interrupt *)header;
>>>> +
>>>> +    if (BAD_MADT_ENTRY(processor, end))
>>>> +            return -EINVAL;
>>>> +
>>>> +    gic_cpu_base = processor->base_address;
>>>> +    if (!gic_cpu_base)
>>>> +            return -EFAULT;
>>>
>>> Is zero an invalid address?
>> Yeah, good point.
>>>
>>>> +
>>>> +    /*
>>>> +     * There is no support for non-banked GICv1/2 register in ACPI spec.
>>>> +     * All CPU interface addresses have to be the same.
>>>> +     */
>>>> +    if (cpu_phy_base != ULONG_MAX && gic_cpu_base != cpu_phy_base)
>>>> +            return -EFAULT;
>>>> +
>>>> +    cpu_phy_base = gic_cpu_base;
>>>> +    return 0;
>>>> +}
>>>> +
>>>> +static int __init
>>>> +gic_acpi_parse_madt_distributor(struct acpi_subtable_header *header,
>>>> +                            const unsigned long end)
>>>> +{
>>>> +    struct acpi_madt_generic_distributor *dist;
>>>> +
>>>> +    dist = (struct acpi_madt_generic_distributor *)header;
>>>> +
>>>> +    if (BAD_MADT_ENTRY(dist, end))
>>>> +            return -EINVAL;
>>>> +
>>>> +    dist_phy_base = dist->base_address;
>>>> +    if (!dist_phy_base)
>>>> +            return -EFAULT;
>>>
>>> Same question about zero.
>>>
>>>> +
>>>> +    return 0;
>>>> +}
>>>> +
>>>> +int __init
>>>> +gic_v2_acpi_init(struct acpi_table_header *table)
>>>> +{
>>>> +    void __iomem *cpu_base, *dist_base;
>>>> +    int count;
>>>> +
>>>> +    /* Collect CPU base addresses */
>>>> +    count = acpi_parse_entries(sizeof(struct acpi_table_madt),
>>>> +                               gic_acpi_parse_madt_cpu, table,
>>>> +                               ACPI_MADT_TYPE_GENERIC_INTERRUPT,
>>>> +                               ACPI_MAX_GIC_CPU_INTERFACE_ENTRIES);
>>>> +    if (count < 0) {
>>>> +            pr_err("Error during GICC entries parsing\n");
>>>> +            return -EFAULT;
>>>> +    } else if (!count) {
>>>> +            /* No GICC entries provided, use address from MADT header */
>>>> +            struct acpi_table_madt *madt = (struct acpi_table_madt *)table;
>>>> +
>>>> +            if (!madt->address)
>>>> +                    return -EFAULT;
>>>> +
>>>> +            cpu_phy_base = (u64)madt->address;
>>>> +    }
>>>> +
>>>> +    /*
>>>> +     * Find distributor base address. We expect one distributor entry since
>>>> +     * ACPI 5.1 spec neither support multi-GIC instances nor GIC cascade.
>>>> +     */
>>>> +    count = acpi_parse_entries(sizeof(struct acpi_table_madt),
>>>> +                               gic_acpi_parse_madt_distributor, table,
>>>> +                               ACPI_MADT_TYPE_GENERIC_DISTRIBUTOR,
>>>> +                               ACPI_MAX_GIC_DISTRIBUTOR_ENTRIES);
>>>> +    if (count <= 0) {
>>>> +            pr_err("Error during GICD entries parsing\n");
>>>> +            return -EFAULT;
>>>> +    } else if (count > 1) {
>>>> +            pr_err("More than one GICD entry detected\n");
>>>> +            return -EINVAL;
>>>> +    }
>>>> +
>>>> +    cpu_base = ioremap(cpu_phy_base, ACPI_GIC_CPU_IF_MEM_SIZE);
>>>> +    if (!cpu_base) {
>>>> +            pr_err("Unable to map GICC registers\n");
>>>> +            return -ENOMEM;
>>>> +    }
>>>> +
>>>> +    dist_base = ioremap(dist_phy_base, ACPI_GIC_DIST_MEM_SIZE);
>>>> +    if (!dist_base) {
>>>> +            pr_err("Unable to map GICD registers\n");
>>>> +            iounmap(cpu_base);
>>>> +            return -ENOMEM;
>>>> +    }
>>>> +
>>>> +    /*
>>>> +     * Initialize zero GIC instance (no multi-GIC support). Also, set GIC
>>>> +     * as default IRQ domain to allow for GSI registration and GSI to IRQ
>>>> +     * number translation (see acpi_register_gsi() and acpi_gsi_to_irq()).
>>>> +     */
>>>> +    gic_init_bases(0, -1, dist_base, cpu_base, 0, NULL);
>>>> +    irq_set_default_host(gic_data[0].domain);
>>>> +    return 0;
>>>> +}
>>>> +#endif
>>>> diff --git a/include/linux/irqchip/arm-gic-acpi.h b/include/linux/irqchip/arm-gic-acpi.h
>>>> new file mode 100644
>>>> index 0000000..ce2ae1a8
>>>> --- /dev/null
>>>> +++ b/include/linux/irqchip/arm-gic-acpi.h
>>>> @@ -0,0 +1,33 @@
>>>> +/*
>>>> + * Copyright (C) 2014, Linaro Ltd.
>>>> + *  Author: Tomasz Nowicki <[email-masked]>
>>>> + *
>>>> + * This program is free software; you can redistribute it and/or modify
>>>> + * it under the terms of the GNU General Public License version 2 as
>>>> + * published by the Free Software Foundation.
>>>> + */
>>>> +
>>>> +#ifndef ARM_GIC_ACPI_H_
>>>> +#define ARM_GIC_ACPI_H_
>>>> +
>>>> +#include <linux/acpi.h>
>>>
>>> Do we need linux/acpi.h here? You could have a separate forward
>>> declaration of struct acpi_table_header, specially in the light of my
>>> last remark below.
>> Indeed, we can do forward declaration instead of #include
>> <linux/acpi.h>. Thanks!
>>
>>>
>>>> +
>>>> +#ifdef CONFIG_ACPI
>>>> +#define ACPI_MAX_GIC_CPU_INTERFACE_ENTRIES  65535
>>>
>>> With GICv2? I doubt it.
>> I will create macro for each GIC driver:
>> #define ACPI_MAX_GICV2_CPU_INTERFACE_ENTRIES    8
>> #define ACPI_MAX_GICV3_CPU_INTERFACE_ENTRIES    65535
>
> Where do you get this value (ACPI_MAX_GICV3_CPU_INTERFACE_ENTRIES) from?
>
>>>
>>>> +#define ACPI_MAX_GIC_DISTRIBUTOR_ENTRIES    1
>>>> +
>>>> +/*
>>>> + * Hard code here, we can not get memory size from MADT (but FDT does),
>>>> + * Actually no need to do that, because this size can be inferred
>>>> + * from GIC spec.
>>>> + */
>>>> +#define ACPI_GIC_DIST_MEM_SIZE              (SZ_64K)
>>>
>>> I don't know which version of the spec you're looking at, but my version
>>> of the GICv2 spec has a 4kB distributor. Also, it would be good to make
>>> obvious which GIC version this define is about.
>> OK
>>
>>>
>>>> +#define ACPI_GIC_CPU_IF_MEM_SIZE    (SZ_8K)
>>>> +
>>>> +void acpi_gic_init(void);
>>>> +int gic_v2_acpi_init(struct acpi_table_header *table);
>>>> +#else
>>>> +static inline void acpi_gic_init(void) { }
>>>> +#endif
>>>> +
>>>> +#endif /* ARM_GIC_ACPI_H_ */
>>>>
>>>
>>> In the end, why do we need a separate file for this? I cannot see
>>> anything that prevents it from being merged with arm-gic.h.
>>>
>>> Thanks,
>>>
>>>        M.
>>>
>> Having only GICv2, it would work. Considering we would do the same for
>> GICv3 (arm-gic-v3.h) there will be register name conflicts for both
>> headers inclusion:
>>
>> [...]
>> #include <linux/irqchip/arm-gic.h>
>> #include <linux/irqchip/arm-gic-v3.h>
>> [...]
>>          err = gic_v3_acpi_init(table);
>>          if (err)
>>                  err = gic_v2_acpi_init(table);
>>          if (err)
>>                  pr_err("Failed to initialize GIC IRQ controller");
>> [...]
>> So instead of changing register names prefix, I choose new header will
>> be less painfully.
>
> Yes, and this is exactly why I pushed back on that last time. I'll
> continue saying that interrupt controllers should be self-probing, with
> ACPI as they are with DT.
>
> Even with the restrictions of ACPI and SBSA, we end-up with at least 2
> main families of interrupt controllers (GICv2 and GICv3), both with a
> number of "interesting" variations (GICv2m and GICv4, to only mention
> those I'm directly involved with).
>
> I can safely predict that the above will become a tangled mess within 18
> months, and the idea of littering the arch code with a bunch of
> hardcoded "if (blah())" doesn't fill me with joy and confidence.
>
> In summary: we have the infrastructure already, just use it.

We had that discussion but I see we still don't have consensus here. It 
would be good to know our direction before we prepare next patch 
version. Arnd any comments on this from you side?

Tomasz