[PATCH RFC 05/11] clocksource/drivers/arm_arch_timer_mmio: Implement arch mem timer deferred probe

[Lorenzo Pieralisi]

Resolving the arch mem timer IRQ on ACPI systems might require
two-steps if the IRQ is wired to an interrupt controller whose
driver has not probed yet at the time the IRQ mapping is carried
out through acpi_register_gsi(), which would result in an
-EPROBE_DEFER return value that in turn should trigger a
driver probe deferral.

Instead of trying to map an IRQ when the arch mem timer device is
created, stash the GSIs number and flag values in the arch_timer_mem_frame
data structure and use it at driver probe time to map the GSIs.

Add -EPROBE_DEFER handling to the arch mem timer driver so
that it can cope with GSIs that are routed to interrupt controllers
whose driver has not yet probed at the time acpi_register_gsi() is
invoked.

Signed-off-by: Lorenzo Pieralisi <lpieralisi@xxxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Marc Zyngier <maz@xxxxxxxxxx>
---
 drivers/acpi/arm64/gtdt.c                 | 27 +++------
 drivers/clocksource/arm_arch_timer_mmio.c | 94 +++++++++++++++++++++++++++++++
 include/clocksource/arm_arch_timer.h      |  4 ++
 3 files changed, 106 insertions(+), 19 deletions(-)

diff --git a/drivers/acpi/arm64/gtdt.c b/drivers/acpi/arm64/gtdt.c
index 00158c8aa6d9..d7248684b2c5 100644
--- a/drivers/acpi/arm64/gtdt.c
+++ b/drivers/acpi/arm64/gtdt.c
@@ -287,23 +287,12 @@ static int __init gtdt_parse_timer_block(struct acpi_gtdt_timer_block *block,
 		if (frame->valid)
 			goto error;
 
-		frame->phys_irq = map_gt_gsi(gtdt_frame->timer_interrupt,
-					     gtdt_frame->timer_flags);
-		if (frame->phys_irq <= 0) {
-			pr_warn("failed to map physical timer irq in frame %d.\n",
-				gtdt_frame->frame_number);
-			goto error;
-		}
+		frame->phys_gsi = gtdt_frame->timer_interrupt;
+		frame->phys_flags = gtdt_frame->timer_flags;
 
 		if (gtdt_frame->virtual_timer_interrupt) {
-			frame->virt_irq =
-				map_gt_gsi(gtdt_frame->virtual_timer_interrupt,
-					   gtdt_frame->virtual_timer_flags);
-			if (frame->virt_irq <= 0) {
-				pr_warn("failed to map virtual timer irq in frame %d.\n",
-					gtdt_frame->frame_number);
-				goto error;
-			}
+			frame->virt_gsi = gtdt_frame->virtual_timer_interrupt;
+			frame->virt_flags = gtdt_frame->virtual_timer_flags;
 		} else {
 			pr_debug("virtual timer in frame %d not implemented.\n",
 				 gtdt_frame->frame_number);
@@ -329,12 +318,12 @@ static int __init gtdt_parse_timer_block(struct acpi_gtdt_timer_block *block,
 
 		frame = &timer_mem->frame[gtdt_frame->frame_number];
 
-		if (frame->phys_irq > 0)
-			acpi_unregister_gsi(gtdt_frame->timer_interrupt);
+		frame->phys_gsi = 0;
+		frame->phys_flags = 0;
 		frame->phys_irq = 0;
 
-		if (frame->virt_irq > 0)
-			acpi_unregister_gsi(gtdt_frame->virtual_timer_interrupt);
+		frame->virt_gsi = 0;
+		frame->virt_flags = 0;
 		frame->virt_irq = 0;
 	} while (i-- > 0 && gtdt_frame--);
 
diff --git a/drivers/clocksource/arm_arch_timer_mmio.c b/drivers/clocksource/arm_arch_timer_mmio.c
index c3f2fe39bdd2..cfa819687e68 100644
--- a/drivers/clocksource/arm_arch_timer_mmio.c
+++ b/drivers/clocksource/arm_arch_timer_mmio.c
@@ -10,6 +10,7 @@
 
 #define pr_fmt(fmt) 	"arch_timer_mmio: " fmt
 
+#include <linux/acpi.h>
 #include <linux/clockchips.h>
 #include <linux/interrupt.h>
 #include <linux/io-64-nonatomic-lo-hi.h>
@@ -205,6 +206,96 @@ static void arch_timer_mmio_unmap_frame_irqs(struct arch_timer_mem_frame *frame)
 	arch_timer_mmio_unmap_irq(&frame->virt_irq);
 }
 
+#ifdef CONFIG_ACPI
+static int arch_timer_mmio_map_gsi(struct platform_device *pdev, u32 gsi,
+				   u32 flags, int *irq)
+{
+	int trigger, polarity, ret;
+
+	if (!gsi || *irq)
+		return 0;
+
+	trigger = (flags & ACPI_GTDT_INTERRUPT_MODE) ? ACPI_EDGE_SENSITIVE
+						     : ACPI_LEVEL_SENSITIVE;
+	polarity = (flags & ACPI_GTDT_INTERRUPT_POLARITY) ? ACPI_ACTIVE_LOW
+							  : ACPI_ACTIVE_HIGH;
+
+	ret = acpi_register_gsi(&pdev->dev, gsi, trigger, polarity);
+	if (ret < 0)
+		return ret;
+
+	*irq = ret;
+
+	return 0;
+}
+
+static int arch_timer_mmio_map_frame_gsis(struct platform_device *pdev,
+					  struct arch_timer_mem_frame *frame)
+{
+	int ret;
+
+	ret = arch_timer_mmio_map_gsi(pdev, frame->phys_gsi, frame->phys_flags, &frame->phys_irq);
+	if (ret < 0) {
+		if (ret == -EPROBE_DEFER)
+			return ret;
+
+		dev_err(&pdev->dev,
+			"Failed to map physical timer GSI %u for frame @ %pa: %d\n",
+			frame->phys_gsi, &frame->cntbase, ret);
+		return ret;
+	}
+
+	ret = arch_timer_mmio_map_gsi(pdev, frame->virt_gsi, frame->virt_flags, &frame->virt_irq);
+	if (ret < 0) {
+		if (ret != -EPROBE_DEFER)
+			dev_err(&pdev->dev,
+				"Failed to map virtual timer GSI %u for frame @ %pa: %d\n",
+				frame->virt_gsi, &frame->cntbase, ret);
+		arch_timer_mmio_unmap_irq(&frame->phys_irq);
+		return ret;
+	}
+
+	return 0;
+}
+
+static int arch_timer_mmio_map_gsis(struct platform_device *pdev,
+				    struct arch_timer_mem *gt_block)
+{
+	int i, ret;
+
+	for (i = 0; i < ARCH_TIMER_MEM_MAX_FRAMES; i++) {
+		struct arch_timer_mem_frame *frame = &gt_block->frame[i];
+
+		if (!frame->valid)
+			continue;
+
+		ret = arch_timer_mmio_map_frame_gsis(pdev, frame);
+		if (ret < 0)
+			goto unmap_err;
+	}
+
+	return 0;
+
+unmap_err:
+	for (i--; i >= 0; i--) {
+		struct arch_timer_mem_frame *frame = &gt_block->frame[i];
+
+		if (!frame->valid)
+			continue;
+
+		arch_timer_mmio_unmap_frame_irqs(frame);
+	}
+
+	return ret;
+}
+#else
+static inline int arch_timer_mmio_map_gsis(struct platform_device *pdev,
+					   struct arch_timer_mem *gt_block)
+{
+	return -ENODEV;
+}
+#endif
+
 static void arch_timer_mmio_unmap_irqs(struct arch_timer_mem *gt_block)
 {
 	int i;
@@ -420,6 +511,9 @@ static int arch_timer_mmio_probe(struct platform_device *pdev)
 			return ret;
 	} else {
 		at->gt_block = dev_get_platdata(&pdev->dev);
+		ret = arch_timer_mmio_map_gsis(pdev, at->gt_block);
+		if (ret)
+			return ret;
 	}
 
 	platform_set_drvdata(pdev, at);
diff --git a/include/clocksource/arm_arch_timer.h b/include/clocksource/arm_arch_timer.h
index 2eda895f19f5..c14741519899 100644
--- a/include/clocksource/arm_arch_timer.h
+++ b/include/clocksource/arm_arch_timer.h
@@ -76,6 +76,10 @@ struct arch_timer_mem_frame {
 	size_t size;
 	int phys_irq;
 	int virt_irq;
+	u32 phys_gsi;
+	u32 phys_flags;
+	u32 virt_gsi;
+	u32 virt_flags;
 };
 
 struct arch_timer_mem {

-- 
2.54.0