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Message-ID: <55C0AFA2.8050704@arm.com>
Date: Tue, 04 Aug 2015 13:27:14 +0100
From: Marc Zyngier <marc.zyngier@....com>
To: Hanjun Guo <hanjun.guo@...aro.org>,
Jason Cooper <jason@...edaemon.net>,
Will Deacon <Will.Deacon@....com>,
Catalin Marinas <Catalin.Marinas@....com>,
"Rafael J. Wysocki" <rjw@...ysocki.net>
CC: Thomas Gleixner <tglx@...utronix.de>,
Jiang Liu <jiang.liu@...ux.intel.com>,
Bjorn Helgaas <bhelgaas@...gle.com>,
Lorenzo Pieralisi <Lorenzo.Pieralisi@....com>,
"suravee.suthikulpanit@....com" <suravee.suthikulpanit@....com>,
Timur Tabi <timur@...eaurora.org>,
Tomasz Nowicki <tomasz.nowicki@...aro.org>,
"grant.likely@...aro.org" <grant.likely@...aro.org>,
Mark Brown <broonie@...nel.org>, Wei Huang <wei@...hat.com>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>,
"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linaro-acpi@...ts.linaro.org" <linaro-acpi@...ts.linaro.org>
Subject: Re: [PATCH v4 02/10] ACPI / irqchip: Add self-probe infrastructure
to initialize IRQ controller
On 29/07/15 11:08, Hanjun Guo wrote:
> This self-probe infrastructure works in the similar way as OF,
> but there is some different in the mechanism:
>
> For DT, the init fn will be called once it finds compatible strings
> in DT, but for ACPI, we init irqchips by static tables, and in
> static ACPI tables, there are no compatible strings to indicate
> irqchips, but thanks to the GIC version presented in ACPI table,
> we can call the corresponding GIC drivers matching the GIC version
> with this framework.
>
> This mechanism can also be used for clock declare and may also works
> on x86 for some table parsing too.
>
> This patch is based on Tomasz Nowicki <tomasz.nowicki@...aro.org>'s
> work.
>
> Signed-off-by: Hanjun Guo <hanjun.guo@...aro.org>
> ---
> drivers/irqchip/irq-gic-acpi.c | 33 +++++++++++++++++++++++++++++++++
> include/asm-generic/vmlinux.lds.h | 13 +++++++++++++
> include/linux/acpi.h | 16 ++++++++++++++++
> include/linux/irqchip.h | 13 +++++++++++++
> include/linux/mod_devicetable.h | 8 ++++++++
> 5 files changed, 83 insertions(+)
>
> diff --git a/drivers/irqchip/irq-gic-acpi.c b/drivers/irqchip/irq-gic-acpi.c
> index 6537b43..011468d 100644
> --- a/drivers/irqchip/irq-gic-acpi.c
> +++ b/drivers/irqchip/irq-gic-acpi.c
> @@ -107,3 +107,36 @@ static int __init acpi_gic_version_init(void)
>
> return 0;
> }
> +
> +/*
> + * This special acpi_table_id is the sentinel at the end of the
> + * acpi_table_id[] array of all irqchips. It is automatically placed at
> + * the end of the array by the linker, thanks to being part of a
> + * special section.
> + */
> +static const struct acpi_table_id
> +irqchip_acpi_match_end __used __section(__irqchip_acpi_table_end);
What is this thing for? Nobody refers to it (I know
drivers/irqchip/irqchip.c has a similar thing, but that's not enough a
reason...).
> +
> +extern struct acpi_table_id __irqchip_acpi_table[];
> +
> +void __init acpi_irqchip_init(void)
> +{
> + struct acpi_table_id *id;
> +
> + if (acpi_disabled)
> + return;
> +
> + if (acpi_gic_version_init())
> + return;
This is the only place where we need the version, right? So just get
acpi_gic_version_init to return the version number, and loose the global
variable.
> +
> + /* scan the irqchip table to match the GIC version and its driver */
> + for (id = __irqchip_acpi_table; id->id[0]; id++) {
> + if (gic_version == (u8)id->driver_data) {
> + acpi_table_parse(id->id,
> + (acpi_tbl_table_handler)id->handler);
> + return;
> + }
> + }
> +
> + pr_err("No matched driver GIC version %d\n", gic_version);
> +}
> diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
> index 8bd374d..625776c 100644
> --- a/include/asm-generic/vmlinux.lds.h
> +++ b/include/asm-generic/vmlinux.lds.h
> @@ -181,6 +181,18 @@
> #define CPUIDLE_METHOD_OF_TABLES() OF_TABLE(CONFIG_CPU_IDLE, cpuidle_method)
> #define EARLYCON_OF_TABLES() OF_TABLE(CONFIG_SERIAL_EARLYCON, earlycon)
>
> +#ifdef CONFIG_ACPI
> +#define ACPI_TABLE(name) \
> + . = ALIGN(8); \
> + VMLINUX_SYMBOL(__##name##_acpi_table) = .; \
> + *(__##name##_acpi_table) \
> + *(__##name##_acpi_table_end)
> +
> +#define IRQCHIP_ACPI_MATCH_TABLE() ACPI_TABLE(irqchip)
> +#else
> +#define IRQCHIP_ACPI_MATCH_TABLE()
> +#endif
> +
> #define KERNEL_DTB() \
> STRUCT_ALIGN(); \
> VMLINUX_SYMBOL(__dtb_start) = .; \
> @@ -516,6 +528,7 @@
> CPUIDLE_METHOD_OF_TABLES() \
> KERNEL_DTB() \
> IRQCHIP_OF_MATCH_TABLE() \
> + IRQCHIP_ACPI_MATCH_TABLE() \
> EARLYCON_TABLE() \
> EARLYCON_OF_TABLES()
>
> diff --git a/include/linux/acpi.h b/include/linux/acpi.h
> index 0820cb1..04dd0bb 100644
> --- a/include/linux/acpi.h
> +++ b/include/linux/acpi.h
> @@ -829,4 +829,20 @@ static inline struct acpi_device *acpi_get_next_child(struct device *dev,
>
> #endif
>
> +#ifdef CONFIG_ACPI
> +#define ACPI_DECLARE(table, name, table_id, data, fn) \
> + static const struct acpi_table_id __acpi_table_##name \
> + __used __section(__##table##_acpi_table) \
> + = { .id = table_id, \
> + .handler = (void *)fn, \
> + .driver_data = data }
> +#else
> +#define ACPI_DECLARE(table, name, table_id, data, fn) \
> + static const struct acpi_table_id __acpi_table_##name \
> + __attribute__((unused)) \
> + = { .id = table_id, \
> + .handler = (void *)fn, \
> + .driver_data = data }
> +#endif
> +
> #endif /*_LINUX_ACPI_H*/
> diff --git a/include/linux/irqchip.h b/include/linux/irqchip.h
> index 6388873..6b66d3e 100644
> --- a/include/linux/irqchip.h
> +++ b/include/linux/irqchip.h
> @@ -11,6 +11,7 @@
> #ifndef _LINUX_IRQCHIP_H
> #define _LINUX_IRQCHIP_H
>
> +#include <linux/acpi.h>
> #include <linux/of.h>
>
> /*
> @@ -25,6 +26,18 @@
> */
> #define IRQCHIP_DECLARE(name, compat, fn) OF_DECLARE_2(irqchip, name, compat, fn)
>
> +/*
> + * This macro must be used by the different ARM GIC drivers to declare
> + * the association between their version and their initialization function.
> + *
> + * @name: name that must be unique accross all IRQCHIP_ACPI_DECLARE of the
> + * same file.
> + * @gic_version: version of GIC
> + * @fn: initialization function
> + */
> +#define IRQCHIP_ACPI_DECLARE(name, gic_version, fn) \
> + ACPI_DECLARE(irqchip, name, ACPI_SIG_MADT, gic_version, fn)
I don't think this is the right approach. The MADT table has a *huge*
number of possible subtables, and none of them is matched by the GIC
version.
What you *really* want is MADT -> GICD -> GIC type. Your ACPI_DECLARE
macro doesn't reflect this at all (you've basically cloned OF, and
that's clearly not good enough).
This probably require an intermediate matching function, ending up with
something like:
#define IRQCHIP_ACPI_DECLARE(name, subtable, version, fn) \
ACPI_DECLARE(irqchip, name, ACPI_SIG_MADT, match_madt_subtable,\
subtable, version, fn)
where match_madt_subtable is going to check that a given subtable is
really suitable for a given irqchip. None of that should be GIC
specific, really.
> +
> #ifdef CONFIG_IRQCHIP
> void irqchip_init(void);
> #else
> diff --git a/include/linux/mod_devicetable.h b/include/linux/mod_devicetable.h
> index 34f25b7..105be1f 100644
> --- a/include/linux/mod_devicetable.h
> +++ b/include/linux/mod_devicetable.h
> @@ -193,6 +193,14 @@ struct acpi_device_id {
> __u32 cls_msk;
> };
>
> +#define ACPI_TABLE_ID_LEN 5
> +
> +struct acpi_table_id {
> + __u8 id[ACPI_TABLE_ID_LEN];
> + const void *handler;
> + kernel_ulong_t driver_data;
> +};
> +
> #define PNP_ID_LEN 8
> #define PNP_MAX_DEVICES 8
>
>
Thanks,
M.
--
Jazz is not dead. It just smells funny...
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