Groups > linux.kernel > #1219206 > unrolled thread

[PATCH 0/5] ACPI probing infrastructure

Started by	Marc Zyngier <marc.zyngier@arm.com>
First post	2015-09-04 19:10 +0200
Last post	2015-09-07 09:00 +0200
Articles	7 — 2 participants

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  [PATCH 0/5] ACPI probing infrastructure Marc Zyngier <marc.zyngier@arm.com> - 2015-09-04 19:10 +0200
    [PATCH 2/5] irqchip/acpi: Add probing infrastructure for ACPI-based irqchips Marc Zyngier <marc.zyngier@arm.com> - 2015-09-04 19:10 +0200
    [PATCH 4/5] clocksource/acpi: Add probing infrastructure for ACPI-based clocksources Marc Zyngier <marc.zyngier@arm.com> - 2015-09-04 19:10 +0200
    [PATCH 5/5] clocksource/arm_arch_timer: Convert to ACPI probing Marc Zyngier <marc.zyngier@arm.com> - 2015-09-04 19:10 +0200
    [PATCH 3/5] irqchip/gic: Convert the GIC driver to ACPI probing Marc Zyngier <marc.zyngier@arm.com> - 2015-09-04 19:10 +0200
    [PATCH 1/5] acpi: Add basic device probing infrastructure Marc Zyngier <marc.zyngier@arm.com> - 2015-09-04 19:10 +0200
    Re: [PATCH 0/5] ACPI probing infrastructure Tomasz Nowicki <tn@semihalf.com> - 2015-09-07 09:00 +0200

#1219206 — [PATCH 0/5] ACPI probing infrastructure

From	Marc Zyngier <marc.zyngier@arm.com>
Date	2015-09-04 19:10 +0200
Subject	[PATCH 0/5] ACPI probing infrastructure
Message-ID	<q52EW-8lv-13@gated-at.bofh.it>

IRQ controllers and timers are the two types of device the kernel
requires before being able to use the device driver model.

ACPI so far lacks a proper probing infrastructure similar to the one
we have with DT, where we're able to declare IRQ chips and
clocksources inside the driver code, and let the core code pick it up
and call us back on a match. This leads to all kind of really ugly
hacks all over the arm64 code and even in the ACPI layer.

It turns out that providing such a probing infrastructure is rather
easy, and provides a much deserved cleanup in both the arch code, the
GIC driver, and the architected timer driver.

I'm sure there is some more code to be deleted, and one can only
wonder why this wasn't done before the arm64 code was initially merged
(the diffstat says it all...).

Patches are against v4.2, and a branch is available at

git://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git acpi/device-probing

Marc Zyngier (5):
  acpi: Add basic device probing infrastructure
  irqchip/acpi: Add probing infrastructure for ACPI-based irqchips
  irqchip/gic: Convert the GIC driver to ACPI probing
  clocksource/acpi: Add probing infrastructure for ACPI-based
    clocksources
  clocksource/arm_arch_timer: Convert to ACPI probing

 arch/arm64/include/asm/acpi.h        |  1 -
 arch/arm64/include/asm/irq.h         | 13 -------
 arch/arm64/kernel/acpi.c             | 25 -------------
 arch/arm64/kernel/time.c             |  6 ----
 drivers/acpi/scan.c                  | 41 +++++++++++++++++++++
 drivers/clocksource/arm_arch_timer.c | 10 +-----
 drivers/clocksource/clksrc-of.c      |  4 +++
 drivers/irqchip/irq-gic.c            | 69 ++++++++++++++++++------------------
 drivers/irqchip/irqchip.c            |  5 ++-
 include/asm-generic/vmlinux.lds.h    | 11 ++++++
 include/linux/acpi.h                 | 56 +++++++++++++++++++++++++++++
 include/linux/acpi_irq.h             | 10 ------
 include/linux/clocksource.h          |  6 ----
 include/linux/irqchip.h              | 16 +++++++++
 include/linux/irqchip/arm-gic-acpi.h | 31 ----------------
 15 files changed, 166 insertions(+), 138 deletions(-)
 delete mode 100644 include/linux/acpi_irq.h
 delete mode 100644 include/linux/irqchip/arm-gic-acpi.h

-- 
2.1.4

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#1219207 — [PATCH 2/5] irqchip/acpi: Add probing infrastructure for ACPI-based irqchips

From	Marc Zyngier <marc.zyngier@arm.com>
Date	2015-09-04 19:10 +0200
Subject	[PATCH 2/5] irqchip/acpi: Add probing infrastructure for ACPI-based irqchips
Message-ID	<q52EW-8lv-11@gated-at.bofh.it>
In reply to	#1219206

DT enjoys a rather nice probing infrastructure for irqchips, while
ACPI is so far stuck into a very distant past.

This patch introduces a declarative API, allowing irqchips to be
self-contained and be called when a particular entry is matched
in the MADT table.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
 arch/arm64/include/asm/irq.h | 11 -----------
 drivers/irqchip/irqchip.c    |  8 +++++---
 include/linux/acpi_irq.h     | 10 ----------
 include/linux/irqchip.h      | 16 ++++++++++++++++
 4 files changed, 21 insertions(+), 24 deletions(-)
 delete mode 100644 include/linux/acpi_irq.h

diff --git a/arch/arm64/include/asm/irq.h b/arch/arm64/include/asm/irq.h
index bbb251b..1a1037a 100644
--- a/arch/arm64/include/asm/irq.h
+++ b/arch/arm64/include/asm/irq.h
@@ -10,15 +10,4 @@ struct pt_regs;
 extern void migrate_irqs(void);
 extern void set_handle_irq(void (*handle_irq)(struct pt_regs *));
 
-static inline void acpi_irq_init(void)
-{
-	/*
-	 * Hardcode ACPI IRQ chip initialization to GICv2 for now.
-	 * Proper irqchip infrastructure will be implemented along with
-	 * incoming  GICv2m|GICv3|ITS bits.
-	 */
-	acpi_gic_init();
-}
-#define acpi_irq_init acpi_irq_init
-
 #endif
diff --git a/drivers/irqchip/irqchip.c b/drivers/irqchip/irqchip.c
index afd1af3..0644d17 100644
--- a/drivers/irqchip/irqchip.c
+++ b/drivers/irqchip/irqchip.c
@@ -8,7 +8,7 @@
  * warranty of any kind, whether express or implied.
  */
 
-#include <linux/acpi_irq.h>
+#include <linux/acpi.h>
 #include <linux/init.h>
 #include <linux/of_irq.h>
 #include <linux/irqchip.h>
@@ -27,6 +27,8 @@ extern struct of_device_id __irqchip_of_table[];
 void __init irqchip_init(void)
 {
 	of_irq_init(__irqchip_of_table);
-
-	acpi_irq_init();
+#if defined(CONFIG_ARM64) && defined(CONFIG_ACPI)
+	acpi_gic_init();	/* Temporary hack */
+#endif
+	acpi_probe_device_table(ACPI_SIG_MADT);
 }
diff --git a/include/linux/acpi_irq.h b/include/linux/acpi_irq.h
deleted file mode 100644
index f10c872..0000000
--- a/include/linux/acpi_irq.h
+++ /dev/null
@@ -1,10 +0,0 @@
-#ifndef _LINUX_ACPI_IRQ_H
-#define _LINUX_ACPI_IRQ_H
-
-#include <linux/irq.h>
-
-#ifndef acpi_irq_init
-static inline void acpi_irq_init(void) { }
-#endif
-
-#endif /* _LINUX_ACPI_IRQ_H */
diff --git a/include/linux/irqchip.h b/include/linux/irqchip.h
index 6388873..1df3123 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 +26,21 @@
  */
 #define IRQCHIP_DECLARE(name, compat, fn) OF_DECLARE_2(irqchip, name, compat, fn)
 
+/*
+ * This macro must be used by the different irqchip 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.
+ * @subtable: Subtable to be identified in MADT
+ * @validate: Function to be called on that subtable to check its validity.
+ *            Can be NULL.
+ * @data: data to be checked by the validate function.
+ * @fn: initialization function
+ */
+#define IRQCHIP_ACPI_DECLARE(name, subtable, validate, data, fn)	\
+	ACPI_DECLARE(device, name, ACPI_SIG_MADT, subtable, validate, data, fn)
+
 #ifdef CONFIG_IRQCHIP
 void irqchip_init(void);
 #else
-- 
2.1.4

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#1219208 — [PATCH 4/5] clocksource/acpi: Add probing infrastructure for ACPI-based clocksources

From	Marc Zyngier <marc.zyngier@arm.com>
Date	2015-09-04 19:10 +0200
Subject	[PATCH 4/5] clocksource/acpi: Add probing infrastructure for ACPI-based clocksources
Message-ID	<q52EX-8lv-17@gated-at.bofh.it>
In reply to	#1219206

DT enjoys a rather nice probing infrastructure for clocksources,
while ACPI is so far stuck into a very distant past.

This patch introduces a declarative API, allowing clocksources
to be self-contained and be called when parsing the GTDT table.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
 drivers/clocksource/clksrc-of.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/clocksource/clksrc-of.c b/drivers/clocksource/clksrc-of.c
index 0093a8e..b351b1e 100644
--- a/drivers/clocksource/clksrc-of.c
+++ b/drivers/clocksource/clksrc-of.c
@@ -14,6 +14,7 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include <linux/acpi.h>
 #include <linux/init.h>
 #include <linux/of.h>
 #include <linux/clocksource.h>
@@ -38,6 +39,9 @@ void __init clocksource_of_init(void)
 		init_func(np);
 		clocksources++;
 	}
+
+	clocksources += acpi_probe_device_table(ACPI_SIG_GTDT);
+
 	if (!clocksources)
 		pr_crit("%s: no matching clocksources found\n", __func__);
 }
-- 
2.1.4

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#1219210 — [PATCH 5/5] clocksource/arm_arch_timer: Convert to ACPI probing

From	Marc Zyngier <marc.zyngier@arm.com>
Date	2015-09-04 19:10 +0200
Subject	[PATCH 5/5] clocksource/arm_arch_timer: Convert to ACPI probing
Message-ID	<q52EX-8lv-27@gated-at.bofh.it>
In reply to	#1219206

It is now absolutely trivial to convert the arch timer driver to
use ACPI probing, just like its DT counterpart.

Let's enjoy another crapectomy.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
 arch/arm64/kernel/time.c             |  6 ------
 drivers/clocksource/arm_arch_timer.c | 10 +---------
 include/linux/clocksource.h          |  6 ------
 3 files changed, 1 insertion(+), 21 deletions(-)

diff --git a/arch/arm64/kernel/time.c b/arch/arm64/kernel/time.c
index 42f9195..4e56739 100644
--- a/arch/arm64/kernel/time.c
+++ b/arch/arm64/kernel/time.c
@@ -73,12 +73,6 @@ void __init time_init(void)
 
 	tick_setup_hrtimer_broadcast();
 
-	/*
-	 * Since ACPI or FDT will only one be available in the system,
-	 * we can use acpi_generic_timer_init() here safely
-	 */
-	acpi_generic_timer_init();
-
 	arch_timer_rate = arch_timer_get_rate();
 	if (!arch_timer_rate)
 		panic("Unable to initialise architected timer.\n");
diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
index 0aa135d..ba4e6f2 100644
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -872,13 +872,5 @@ static int __init arch_timer_acpi_init(struct acpi_table_header *table)
 	arch_timer_init();
 	return 0;
 }
-
-/* Initialize all the generic timers presented in GTDT */
-void __init acpi_generic_timer_init(void)
-{
-	if (acpi_disabled)
-		return;
-
-	acpi_table_parse(ACPI_SIG_GTDT, arch_timer_acpi_init);
-}
+DEVICE_ACPI_DECLARE(arch_timer, ACPI_SIG_GTDT, arch_timer_acpi_init);
 #endif
diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h
index 278dd27..a25fc6e 100644
--- a/include/linux/clocksource.h
+++ b/include/linux/clocksource.h
@@ -252,10 +252,4 @@ extern void clocksource_of_init(void);
 static inline void clocksource_of_init(void) {}
 #endif
 
-#ifdef CONFIG_ACPI
-void acpi_generic_timer_init(void);
-#else
-static inline void acpi_generic_timer_init(void) { }
-#endif
-
 #endif /* _LINUX_CLOCKSOURCE_H */
-- 
2.1.4

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#1219212 — [PATCH 3/5] irqchip/gic: Convert the GIC driver to ACPI probing

From	Marc Zyngier <marc.zyngier@arm.com>
Date	2015-09-04 19:10 +0200
Subject	[PATCH 3/5] irqchip/gic: Convert the GIC driver to ACPI probing
Message-ID	<q52EX-8lv-31@gated-at.bofh.it>
In reply to	#1219206

Now that we have a basic infrastructure to register irqchips and
call them on discovery of a matching entry in MADT, convert the
GIC driver to this new probing method.

It ends up being a code deletion party, which is a rather good thing.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
 arch/arm64/include/asm/acpi.h        |  1 -
 arch/arm64/include/asm/irq.h         |  2 --
 arch/arm64/kernel/acpi.c             | 25 -------------
 drivers/irqchip/irq-gic.c            | 69 ++++++++++++++++++------------------
 drivers/irqchip/irqchip.c            |  3 --
 include/linux/irqchip/arm-gic-acpi.h | 31 ----------------
 6 files changed, 35 insertions(+), 96 deletions(-)
 delete 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 406485e..de97359 100644
--- a/arch/arm64/include/asm/acpi.h
+++ b/arch/arm64/include/asm/acpi.h
@@ -13,7 +13,6 @@
 #define _ASM_ACPI_H
 
 #include <linux/mm.h>
-#include <linux/irqchip/arm-gic-acpi.h>
 
 #include <asm/cputype.h>
 #include <asm/psci.h>
diff --git a/arch/arm64/include/asm/irq.h b/arch/arm64/include/asm/irq.h
index 1a1037a..94c5367 100644
--- a/arch/arm64/include/asm/irq.h
+++ b/arch/arm64/include/asm/irq.h
@@ -1,8 +1,6 @@
 #ifndef __ASM_IRQ_H
 #define __ASM_IRQ_H
 
-#include <linux/irqchip/arm-gic-acpi.h>
-
 #include <asm-generic/irq.h>
 
 struct pt_regs;
diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c
index 19de753..d6463bb 100644
--- a/arch/arm64/kernel/acpi.c
+++ b/arch/arm64/kernel/acpi.c
@@ -205,28 +205,3 @@ void __init acpi_boot_table_init(void)
 			disable_acpi();
 	}
 }
-
-void __init acpi_gic_init(void)
-{
-	struct acpi_table_header *table;
-	acpi_status status;
-	acpi_size tbl_size;
-	int err;
-
-	if (acpi_disabled)
-		return;
-
-	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");
-
-	early_acpi_os_unmap_memory((char *)table, tbl_size);
-}
diff --git a/drivers/irqchip/irq-gic.c b/drivers/irqchip/irq-gic.c
index 4dd8826..5570f5c 100644
--- a/drivers/irqchip/irq-gic.c
+++ b/drivers/irqchip/irq-gic.c
@@ -40,7 +40,6 @@
 #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>
@@ -1043,7 +1042,7 @@ IRQCHIP_DECLARE(msm_qgic2, "qcom,msm-qgic2", gic_of_init);
 #endif
 
 #ifdef CONFIG_ACPI
-static phys_addr_t dist_phy_base, cpu_phy_base __initdata;
+static phys_addr_t cpu_phy_base __initdata;
 
 static int __init
 gic_acpi_parse_madt_cpu(struct acpi_subtable_header *header,
@@ -1071,60 +1070,56 @@ gic_acpi_parse_madt_cpu(struct acpi_subtable_header *header,
 	return 0;
 }
 
-static int __init
-gic_acpi_parse_madt_distributor(struct acpi_subtable_header *header,
-				const unsigned long end)
+/* The things you have to do to just *count* something... */
+static int __init acpi_dummy_func(struct acpi_subtable_header *header,
+				  const unsigned long end)
 {
-	struct acpi_madt_generic_distributor *dist;
+	return 0;
+}
 
-	dist = (struct acpi_madt_generic_distributor *)header;
+static bool __init acpi_gic_redist_is_present(void)
+{
+	return acpi_table_parse_madt(ACPI_MADT_TYPE_GENERIC_REDISTRIBUTOR,
+				     acpi_dummy_func, 0) > 0;
+}
 
-	if (BAD_MADT_ENTRY(dist, end))
-		return -EINVAL;
+static bool __init gic_validate_dist(struct acpi_subtable_header *header,
+				     struct acpi_probe_entry *ape)
+{
+	struct acpi_madt_generic_distributor *dist;
+	dist = (struct acpi_madt_generic_distributor *)header;
 
-	dist_phy_base = dist->base_address;
-	return 0;
+	return (dist->version == ape->driver_data &&
+		(dist->version != ACPI_MADT_GIC_VERSION_NONE ||
+		 !acpi_gic_redist_is_present()));
 }
 
-int __init
-gic_v2_acpi_init(struct acpi_table_header *table)
+#define ACPI_GICV2_DIST_MEM_SIZE	(SZ_4K)
+#define ACPI_GIC_CPU_IF_MEM_SIZE	(SZ_8K)
+
+static int __init gic_v2_acpi_init(struct acpi_subtable_header *header,
+				   const unsigned long end)
 {
+	struct acpi_madt_generic_distributor *dist;
 	void __iomem *cpu_base, *dist_base;
 	int count;
 
 	/* Collect CPU base addresses */
-	count = acpi_parse_entries(ACPI_SIG_MADT,
-				   sizeof(struct acpi_table_madt),
-				   gic_acpi_parse_madt_cpu, table,
-				   ACPI_MADT_TYPE_GENERIC_INTERRUPT, 0);
+	count = acpi_table_parse_madt(ACPI_MADT_TYPE_GENERIC_INTERRUPT,
+				      gic_acpi_parse_madt_cpu, 0);
 	if (count <= 0) {
 		pr_err("No valid GICC entries exist\n");
 		return -EINVAL;
 	}
 
-	/*
-	 * 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(ACPI_SIG_MADT,
-				   sizeof(struct acpi_table_madt),
-				   gic_acpi_parse_madt_distributor, table,
-				   ACPI_MADT_TYPE_GENERIC_DISTRIBUTOR, 0);
-	if (count <= 0) {
-		pr_err("No valid GICD entries exist\n");
-		return -EINVAL;
-	} 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_GICV2_DIST_MEM_SIZE);
+	dist = (struct acpi_madt_generic_distributor *)header;
+	dist_base = ioremap(dist->base_address, ACPI_GICV2_DIST_MEM_SIZE);
 	if (!dist_base) {
 		pr_err("Unable to map GICD registers\n");
 		iounmap(cpu_base);
@@ -1142,4 +1137,10 @@ gic_v2_acpi_init(struct acpi_table_header *table)
 	acpi_irq_model = ACPI_IRQ_MODEL_GIC;
 	return 0;
 }
+IRQCHIP_ACPI_DECLARE(gic_v2, ACPI_MADT_TYPE_GENERIC_DISTRIBUTOR,
+		     gic_validate_dist, ACPI_MADT_GIC_VERSION_V2,
+		     gic_v2_acpi_init);
+IRQCHIP_ACPI_DECLARE(gic_v2_maybe, ACPI_MADT_TYPE_GENERIC_DISTRIBUTOR,
+		     gic_validate_dist, ACPI_MADT_GIC_VERSION_NONE,
+		     gic_v2_acpi_init);
 #endif
diff --git a/drivers/irqchip/irqchip.c b/drivers/irqchip/irqchip.c
index 0644d17..639fd32 100644
--- a/drivers/irqchip/irqchip.c
+++ b/drivers/irqchip/irqchip.c
@@ -27,8 +27,5 @@ extern struct of_device_id __irqchip_of_table[];
 void __init irqchip_init(void)
 {
 	of_irq_init(__irqchip_of_table);
-#if defined(CONFIG_ARM64) && defined(CONFIG_ACPI)
-	acpi_gic_init();	/* Temporary hack */
-#endif
 	acpi_probe_device_table(ACPI_SIG_MADT);
 }
diff --git a/include/linux/irqchip/arm-gic-acpi.h b/include/linux/irqchip/arm-gic-acpi.h
deleted file mode 100644
index de3419e..0000000
--- a/include/linux/irqchip/arm-gic-acpi.h
+++ /dev/null
@@ -1,31 +0,0 @@
-/*
- * Copyright (C) 2014, Linaro Ltd.
- *	Author: Tomasz Nowicki <tomasz.nowicki@linaro.org>
- *
- * 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_
-
-#ifdef CONFIG_ACPI
-
-/*
- * 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_GICV2_DIST_MEM_SIZE	(SZ_4K)
-#define ACPI_GIC_CPU_IF_MEM_SIZE	(SZ_8K)
-
-struct acpi_table_header;
-
-int gic_v2_acpi_init(struct acpi_table_header *table);
-void acpi_gic_init(void);
-#else
-static inline void acpi_gic_init(void) { }
-#endif
-
-#endif /* ARM_GIC_ACPI_H_ */
-- 
2.1.4

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#1219214 — [PATCH 1/5] acpi: Add basic device probing infrastructure

From	Marc Zyngier <marc.zyngier@arm.com>
Date	2015-09-04 19:10 +0200
Subject	[PATCH 1/5] acpi: Add basic device probing infrastructure
Message-ID	<q52EX-8lv-33@gated-at.bofh.it>
In reply to	#1219206

IRQ controllers and timers are the two types of device the kernel
requires before being able to use the device driver model.

ACPI so far lacks a proper probing infrastructure similar to the one
we have with DT, where we're able to declare IRQ chips and
clocksources inside the driver code, and let the core code pick it up
and call us back on a match. This leads to all kind of really ugly
hacks all over the arm64 code and even in the ACPI layer.

In order to allow some basic probing based on the ACPI tables,
introduce "struct acpi_probe_entry" which contains just enough
data and callbacks to match a table, an optional subtable, and
call a probe function. A driver can, at build time, register itself
and expect being called if the right entry exists in the ACPI
table.

A acpi_probe_device_init() is provided, taking an ACPI table
identifier, and iterating over the registered entries.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
 drivers/acpi/scan.c               | 41 ++++++++++++++++++++++++++++
 include/asm-generic/vmlinux.lds.h | 11 ++++++++
 include/linux/acpi.h              | 56 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 108 insertions(+)

diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index ec25635..9e920ec 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -2793,3 +2793,44 @@ int __init acpi_scan_init(void)
 	mutex_unlock(&acpi_scan_lock);
 	return result;
 }
+
+static const struct acpi_probe_entry device_acpi_probe_end
+		__used __section(__device_acpi_probe_table_end);
+extern struct acpi_probe_entry __device_acpi_probe_table[];
+static struct acpi_probe_entry *ape;
+static int acpi_probe_count;
+static DEFINE_SPINLOCK(acpi_probe_lock);
+
+static int __init acpi_match_madt(struct acpi_subtable_header *header,
+				  const unsigned long end)
+{
+	if (!ape->validate_subtbl || ape->validate_subtbl(header, ape))
+		if (!ape->probe_subtbl(header, end))
+			acpi_probe_count++;
+
+	return 0;
+}
+
+int __init acpi_probe_device_table(const char *id)
+{
+	int count = 0;
+
+	if (acpi_disabled)
+		return 0;
+
+	spin_lock(&acpi_probe_lock);
+	for (ape = __device_acpi_probe_table; ape->probe_table; ape++) {
+		if (!ACPI_COMPARE_NAME(id, ape->id))
+			continue;
+		if (ACPI_COMPARE_NAME(ACPI_SIG_MADT, ape->id)) {
+			acpi_probe_count = 0;
+			acpi_table_parse_madt(ape->type, acpi_match_madt, 0);
+			count += acpi_probe_count;
+		} else {
+			count = acpi_table_parse(ape->id, ape->probe_table);
+		}
+	}
+	spin_unlock(&acpi_probe_lock);
+
+	return count;
+}
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index 8bd374d..875397a 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -181,6 +181,16 @@
 #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_PROBE_TABLE(name)						\
+	. = ALIGN(8);							\
+	VMLINUX_SYMBOL(__##name##_acpi_probe_table) = .;		\
+	*(__##name##_acpi_probe_table)					\
+	*(__##name##_acpi_probe_table_end)
+#else
+#define ACPI_PROBE_TABLE(name)
+#endif
+
 #define KERNEL_DTB()							\
 	STRUCT_ALIGN();							\
 	VMLINUX_SYMBOL(__dtb_start) = .;				\
@@ -516,6 +526,7 @@
 	CPUIDLE_METHOD_OF_TABLES()					\
 	KERNEL_DTB()							\
 	IRQCHIP_OF_MATCH_TABLE()					\
+	ACPI_PROBE_TABLE(device)					\
 	EARLYCON_TABLE()						\
 	EARLYCON_OF_TABLES()
 
diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index d2445fa..bf6dfb9 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -763,6 +763,52 @@ int acpi_dev_prop_read(struct acpi_device *adev, const char *propname,
 
 struct acpi_device *acpi_get_next_child(struct device *dev,
 					struct acpi_device *child);
+
+struct acpi_probe_entry;
+typedef bool (*acpi_probe_entry_validate_subtbl)(struct acpi_subtable_header *,
+						 struct acpi_probe_entry *);
+
+#define ACPI_TABLE_ID_LEN	5
+
+/**
+ * struct acpi_probe_entry - boot-time probing entry
+ * @id:			ACPI table name
+ * @type:		Optional subtable type to match
+ *			(if @id contains subtables)
+ * @validate_subtbl:	Optional callback to check the validity of
+ *			the subtable
+ * @probe_table:	Callback to the driver being probed when table
+ *			match is successful
+ * @probe_subtbl:	Callback to the driver being probed when table and
+ *			subtable match (and optionnal callback is successful)
+ * @driver_data:	Sideband data provided back to the driver
+ */
+struct acpi_probe_entry {
+	__u8 id[ACPI_TABLE_ID_LEN];
+	__u8 type;
+	acpi_probe_entry_validate_subtbl validate_subtbl;
+	union {
+		acpi_tbl_table_handler probe_table;
+		acpi_tbl_entry_handler probe_subtbl;
+	};
+	kernel_ulong_t driver_data;
+};
+
+#define ACPI_DECLARE(table, name, table_id, subtable, valid, data, fn)	\
+	static const struct acpi_probe_entry __acpi_probe_##name	\
+		__used __section(__##table##_acpi_probe_table)		\
+		 = {							\
+			.id = table_id,					\
+			.type = subtable,				\
+			.validate_subtbl = valid,			\
+			.probe_table = (acpi_tbl_table_handler)fn,	\
+			.driver_data = data, 				\
+		   }
+
+#define DEVICE_ACPI_DECLARE(name, table_id, fn)				\
+	ACPI_DECLARE(device, name, table_id, 0, NULL, 0, fn)
+
+int acpi_probe_device_table(const char *id);
 #else
 static inline int acpi_dev_get_property(struct acpi_device *adev,
 					const char *name, acpi_object_type type,
@@ -813,6 +859,16 @@ static inline struct acpi_device *acpi_get_next_child(struct device *dev,
 	return NULL;
 }
 
+#define ACPI_DECLARE(table, name, table_id, subtable, validate, data, fn) \
+	static const void * __acpi_table_##name[]			\
+		__attribute__((unused))					\
+		 = { (void *) table_id,					\
+		     (void *) subtable,					\
+		     (void *) valid,					\
+		     (void *) fn,					\
+		     (void *) data }
+
+static inline int acpi_probe_device_table(const char *id) { return 0; }
 #endif
 
 #endif	/*_LINUX_ACPI_H*/
-- 
2.1.4

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#1219955

From	Tomasz Nowicki <tn@semihalf.com>
Date	2015-09-07 09:00 +0200
Message-ID	<q5Yzg-6qO-3@gated-at.bofh.it>
In reply to	#1219206

Hi Marc,

On 04.09.2015 19:06, Marc Zyngier wrote:
> IRQ controllers and timers are the two types of device the kernel
> requires before being able to use the device driver model.
>
> ACPI so far lacks a proper probing infrastructure similar to the one
> we have with DT, where we're able to declare IRQ chips and
> clocksources inside the driver code, and let the core code pick it up
> and call us back on a match. This leads to all kind of really ugly
> hacks all over the arm64 code and even in the ACPI layer.
>
> It turns out that providing such a probing infrastructure is rather
> easy, and provides a much deserved cleanup in both the arch code, the
> GIC driver, and the architected timer driver.
>
> I'm sure there is some more code to be deleted, and one can only
> wonder why this wasn't done before the arm64 code was initially merged
> (the diffstat says it all...).
>
> Patches are against v4.2, and a branch is available at
>
> git://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git acpi/device-probing
>
> Marc Zyngier (5):
>    acpi: Add basic device probing infrastructure
>    irqchip/acpi: Add probing infrastructure for ACPI-based irqchips
>    irqchip/gic: Convert the GIC driver to ACPI probing
>    clocksource/acpi: Add probing infrastructure for ACPI-based
>      clocksources
>    clocksource/arm_arch_timer: Convert to ACPI probing
>
>   arch/arm64/include/asm/acpi.h        |  1 -
>   arch/arm64/include/asm/irq.h         | 13 -------
>   arch/arm64/kernel/acpi.c             | 25 -------------
>   arch/arm64/kernel/time.c             |  6 ----
>   drivers/acpi/scan.c                  | 41 +++++++++++++++++++++
>   drivers/clocksource/arm_arch_timer.c | 10 +-----
>   drivers/clocksource/clksrc-of.c      |  4 +++
>   drivers/irqchip/irq-gic.c            | 69 ++++++++++++++++++------------------
>   drivers/irqchip/irqchip.c            |  5 ++-
>   include/asm-generic/vmlinux.lds.h    | 11 ++++++
>   include/linux/acpi.h                 | 56 +++++++++++++++++++++++++++++
>   include/linux/acpi_irq.h             | 10 ------
>   include/linux/clocksource.h          |  6 ----
>   include/linux/irqchip.h              | 16 +++++++++
>   include/linux/irqchip/arm-gic-acpi.h | 31 ----------------
>   15 files changed, 166 insertions(+), 138 deletions(-)
>   delete mode 100644 include/linux/acpi_irq.h
>   delete mode 100644 include/linux/irqchip/arm-gic-acpi.h
>

Thanks for cleaning this up!

For the whole series:
Acked-by: Tomasz Nowicki <tn@semihalf.com>
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csiph-web

[PATCH 0/5] ACPI probing infrastructure

Contents

#1219206 — [PATCH 0/5] ACPI probing infrastructure

#1219207 — [PATCH 2/5] irqchip/acpi: Add probing infrastructure for ACPI-based irqchips

#1219208 — [PATCH 4/5] clocksource/acpi: Add probing infrastructure for ACPI-based clocksources

#1219210 — [PATCH 5/5] clocksource/arm_arch_timer: Convert to ACPI probing

#1219212 — [PATCH 3/5] irqchip/gic: Convert the GIC driver to ACPI probing

#1219214 — [PATCH 1/5] acpi: Add basic device probing infrastructure

#1219955