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Message-ID: <52E15756.4060705@arm.com>
Date: Thu, 23 Jan 2014 17:54:30 +0000
From: Marc Zyngier <marc.zyngier@....com>
To: Hanjun Guo <hanjun.guo@...aro.org>
CC: "Rafael J. Wysocki" <rjw@...ysocki.net>,
Catalin Marinas <Catalin.Marinas@....com>,
Will Deacon <Will.Deacon@....com>,
Russell King - ARM Linux <linux@....linux.org.uk>,
Mark Rutland <Mark.Rutland@....com>,
Matthew Garrett <mjg59@...f.ucam.org>,
"linaro-kernel@...ts.linaro.org" <linaro-kernel@...ts.linaro.org>,
Arnd Bergmann <arnd@...db.de>, Rob Herring <robh@...nel.org>,
Linus Walleij <linus.walleij@...aro.org>,
Olof Johansson <olof@...om.net>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linaro-acpi@...ts.linaro.org" <linaro-acpi@...ts.linaro.org>,
"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
"patches@...aro.org" <patches@...aro.org>,
"grant.likely@...aro.org" <grant.likely@...aro.org>,
Bjorn Helgaas <bhelgaas@...gle.com>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>,
Charles Garcia-Tobin <Charles.Garcia-Tobin@....com>
Subject: Re: [PATCH 09/20] ARM64 / ACPI: Implement core functions for parsing
MADT table
Hi Hanjun,
On 17/01/14 12:25, Hanjun Guo wrote:
> Implement core functions for parsing MADT table to get the information
> about GIC cpu interface and GIC distributor to prepare for SMP and GIC
> initialization.
>
> Signed-off-by: Hanjun Guo <hanjun.guo@...aro.org>
> ---
> arch/arm64/include/asm/acpi.h | 3 +
> drivers/acpi/plat/arm-core.c | 139 ++++++++++++++++++++++++++++++++++++++++-
> drivers/acpi/tables.c | 21 +++++++
> 3 files changed, 162 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm64/include/asm/acpi.h b/arch/arm64/include/asm/acpi.h
> index e108d9c..c335c6d 100644
> --- a/arch/arm64/include/asm/acpi.h
> +++ b/arch/arm64/include/asm/acpi.h
> @@ -83,6 +83,9 @@ void arch_fix_phys_package_id(int num, u32 slot);
> extern int (*acpi_suspend_lowlevel)(void);
> #define acpi_wakeup_address (0)
>
> +#define MAX_GIC_CPU_INTERFACE 256
I'll bite. Where on Earth is this value coming from? If that's for
GICv2, 8 is the maximum. For GICv3+, that's incredibly low, and should
be probed probed at runtime anyway.
> +#define MAX_GIC_DISTRIBUTOR 1 /* should be the same as MAX_GIC_NR */
No support for cascaded GICs?
> +
> #else /* !CONFIG_ACPI */
> #define acpi_disabled 1 /* ACPI sometimes enabled on ARM */
> #define acpi_noirq 1 /* ACPI sometimes enabled on ARM */
> diff --git a/drivers/acpi/plat/arm-core.c b/drivers/acpi/plat/arm-core.c
> index 1835b21..8ba3e6f 100644
> --- a/drivers/acpi/plat/arm-core.c
> +++ b/drivers/acpi/plat/arm-core.c
> @@ -46,6 +46,16 @@ EXPORT_SYMBOL(acpi_disabled);
> int acpi_pci_disabled; /* skip ACPI PCI scan and IRQ initialization */
> EXPORT_SYMBOL(acpi_pci_disabled);
>
> +/*
> + * Local interrupt controller address,
> + * GIC cpu interface base address on ARM/ARM64
> + */
> +static u64 acpi_lapic_addr __initdata;
If that's a GIC address, why not call it as such?
> +#define BAD_MADT_ENTRY(entry, end) ( \
> + (!entry) || (unsigned long)entry + sizeof(*entry) > end || \
> + ((struct acpi_subtable_header *)entry)->length < sizeof(*entry))
> +
> #define PREFIX "ACPI: "
Just do:
#define pr_fmt(fmt) "ACPI: " fmt
and remove all the occurrences of PREFIX.
> /* FIXME: this function should be moved to topology.c when it is ready */
> @@ -92,6 +102,115 @@ void __init __acpi_unmap_table(char *map, unsigned long size)
> return;
> }
>
> +static int __init acpi_parse_madt(struct acpi_table_header *table)
> +{
> + struct acpi_table_madt *madt = NULL;
No need to initialize this to NULL, you're doing an assignment at the
next line...
> +
> + madt = (struct acpi_table_madt *)table;
> + if (!madt) {
> + pr_warn(PREFIX "Unable to map MADT\n");
There is no mapping here, please fix the message accordingly.
> + return -ENODEV;
> + }
> +
> + if (madt->address) {
> + acpi_lapic_addr = (u64) madt->address;
So you're updating this static variable, for the distributor and each
CPU interface? /me puzzled...
> + pr_info(PREFIX "Local APIC address 0x%08x\n", madt->address);
Away with this APIC madness. GICC and GICD are the concepts we're all
familiar with here, and using the proper terminology would certainly
help reviewing these patches...
> + }
> +
> + return 0;
> +}
> +
> +/*
> + * GIC structures on ARM are somthing like Local APIC structures on x86,
> + * which means GIC cpu interfaces for GICv2/v3. Every GIC structure in
> + * MADT table represents a cpu in the system.
And what do you do when your GICv3 doesn't have a memory-mapped
interface, but only uses system registers?
> + * GIC distributor structures are somthing like IOAPIC on x86. GIC can
> + * be initialized with information in this structure.
> + *
> + * Please refer to chapter5.2.12.14/15 of ACPI 5.0
A pointer to that documentation?
> + */
> +
> +static int __init
> +acpi_parse_gic(struct acpi_subtable_header *header, const unsigned long end)
> +{
> + struct acpi_madt_generic_interrupt *processor = NULL;
> +
> + processor = (struct acpi_madt_generic_interrupt *)header;
> +
> + if (BAD_MADT_ENTRY(processor, end))
> + return -EINVAL;
> +
> + acpi_table_print_madt_entry(header);
> +
> + return 0;
> +}
> +
> +static int __init
> +acpi_parse_gic_distributor(struct acpi_subtable_header *header,
> + const unsigned long end)
> +{
> + struct acpi_madt_generic_distributor *distributor = NULL;
> +
> + distributor = (struct acpi_madt_generic_distributor *)header;
> +
> + if (BAD_MADT_ENTRY(distributor, end))
> + return -EINVAL;
> +
> + acpi_table_print_madt_entry(header);
> +
> + return 0;
> +}
> +
> +/*
> + * Parse GIC cpu interface related entries in MADT
> + * returns 0 on success, < 0 on error
> + */
> +static int __init acpi_parse_madt_gic_entries(void)
> +{
> + int count;
> +
> + /*
> + * do a partial walk of MADT to determine how many CPUs
> + * we have including disabled CPUs
> + */
> + count = acpi_table_parse_madt(ACPI_MADT_TYPE_GENERIC_INTERRUPT,
> + acpi_parse_gic, MAX_GIC_CPU_INTERFACE);
> +
> + if (!count) {
> + pr_err(PREFIX "No GIC entries present\n");
> + return -ENODEV;
> + } else if (count < 0) {
> + pr_err(PREFIX "Error parsing GIC entry\n");
> + return count;
> + }
So you do a lot of parsing to count stuff, and then discard the number
of counted objects... You might as well check that there is at least one
valid object and stop there.
> + return 0;
> +}
> +
> +/*
> + * Parse GIC distributor related entries in MADT
> + * returns 0 on success, < 0 on error
> + */
> +static int __init acpi_parse_madt_gic_distributor_entries(void)
> +{
> + int count;
> +
> + count = acpi_table_parse_madt(ACPI_MADT_TYPE_GENERIC_DISTRIBUTOR,
> + acpi_parse_gic_distributor, MAX_GIC_DISTRIBUTOR);
> +
> + if (!count) {
> + pr_err(PREFIX "No GIC distributor entries present\n");
> + return -ENODEV;
> + } else if (count < 0) {
> + pr_err(PREFIX "Error parsing GIC distributor entry\n");
> + return count;
> + }
> +
> + return 0;
> +}
> +
> int acpi_gsi_to_irq(u32 gsi, unsigned int *irq)
> {
> *irq = gsi_to_irq(gsi);
> @@ -141,11 +260,29 @@ static int __init acpi_parse_fadt(struct acpi_table_header *table)
>
> static void __init early_acpi_process_madt(void)
> {
> - return;
> + acpi_table_parse(ACPI_SIG_MADT, acpi_parse_madt);
> }
>
> static void __init acpi_process_madt(void)
> {
> + int error;
> +
> + if (!acpi_table_parse(ACPI_SIG_MADT, acpi_parse_madt)) {
How many times are you going to parse the same table? Surely you can
stash whatever information you need and be done with it?
> + /*
> + * Parse MADT GIC cpu interface entries
> + */
> + error = acpi_parse_madt_gic_entries();
> + if (!error) {
> + /*
> + * Parse MADT GIC distributor entries
> + */
> + acpi_parse_madt_gic_distributor_entries();
> + }
> + }
> +
> + pr_info("Using ACPI for processor (GIC) configuration information\n");
> +
> return;
> }
>
> diff --git a/drivers/acpi/tables.c b/drivers/acpi/tables.c
> index d67a1fe..b3e4615 100644
> --- a/drivers/acpi/tables.c
> +++ b/drivers/acpi/tables.c
> @@ -191,6 +191,27 @@ void acpi_table_print_madt_entry(struct acpi_subtable_header *header)
> }
> break;
>
> + case ACPI_MADT_TYPE_GENERIC_INTERRUPT:
> + {
> + struct acpi_madt_generic_interrupt *p =
> + (struct acpi_madt_generic_interrupt *)header;
> + printk(KERN_INFO PREFIX
Use pr_info
> + "GIC (acpi_id[0x%04x] gic_id[0x%04x] %s)\n",
> + p->uid, p->gic_id,
> + (p->flags & ACPI_MADT_ENABLED) ? "enabled" : "disabled");
> + }
> + break;
> +
> + case ACPI_MADT_TYPE_GENERIC_DISTRIBUTOR:
> + {
> + struct acpi_madt_generic_distributor *p =
> + (struct acpi_madt_generic_distributor *)header;
> + printk(KERN_INFO PREFIX
> + "GIC Distributor (id[0x%04x] address[0x%08llx] gsi_base[%d])\n",
> + p->gic_id, p->base_address, p->global_irq_base);
> + }
> + break;
> +
> default:
> printk(KERN_WARNING PREFIX
> "Found unsupported MADT entry (type = 0x%x)\n",
>
Most of that code seems to be repeatedly parsing and printing stuff, and
I fail to see what it actually does.
M.
--
Jazz is not dead. It just smells funny...
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