Re: [PATCH V14 14/15] irqchip / ACPI: Introduce ACPI_IRQ_MODEL_LPIC for LoongArch

From: Jianmin Lv
Date: Thu Jul 14 2022 - 06:03:13 EST

On 2022/7/8 上午11:17, Jianmin Lv wrote:

On 2022/7/7 下午8:59, Marc Zyngier wrote:
On Sun, 03 Jul 2022 09:45:31 +0100,
Jianmin Lv <lvjianmin@xxxxxxxxxxx> wrote:

For LoongArch, ACPI_IRQ_MODEL_LPIC is introduced, and then the
callback acpi_get_gsi_domain_id and acpi_gsi_to_irq_fallback are

The acpi_get_gsi_domain_id callback returns related fwnode handle
of irqdomain for different GSI range.

The acpi_gsi_to_irq_fallback will create new mapping for gsi when
the mapping of it is not found.

Signed-off-by: Jianmin Lv <lvjianmin@xxxxxxxxxxx>
  drivers/acpi/bus.c                  |  3 +++
  drivers/irqchip/irq-loongarch-cpu.c | 37 +++++++++++++++++++++++++++++++++++++
  include/linux/acpi.h                |  1 +
  3 files changed, 41 insertions(+)

diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c
index 86fa61a..63fbf00 100644
--- a/drivers/acpi/bus.c
+++ b/drivers/acpi/bus.c
@@ -1145,6 +1145,9 @@ static int __init acpi_bus_init_irq(void)
          message = "platform specific model";
+        message = "LPIC";
+        break;
          pr_info("Unknown interrupt routing model\n");
          return -ENODEV;
diff --git a/drivers/irqchip/irq-loongarch-cpu.c b/drivers/irqchip/irq-loongarch-cpu.c
index c2f7411..1b241d7 100644
--- a/drivers/irqchip/irq-loongarch-cpu.c
+++ b/drivers/irqchip/irq-loongarch-cpu.c
@@ -15,6 +15,41 @@
  static struct irq_domain *irq_domain;
+static int lpic_gsi_to_irq(u32 gsi)
+    /* Only pch irqdomain transferring is required for LoongArch. */
+    if (gsi >= GSI_MIN_PCH_IRQ && gsi <= GSI_MAX_PCH_IRQ)
+        return acpi_register_gsi(NULL, gsi, ACPI_LEVEL_SENSITIVE, ACPI_ACTIVE_HIGH);
+    return -1;

The expected return value on failure is 0 (which indicates that no
interrupt was mapped). Here, things will break as acpi_gsi_to_irq()
stores the result as unsigned, and compares the result to 0.

Ok, thanks, I'll change the return value to 0 on failure and change return type to unsigned int.

Hi, Marc, if the return type is changed to unsigned int, the return type of the fallback handler in the patch:
ACPI: irq: Allow acpi_gsi_to_irq() to have an arch-specific fallback

should be changed to unsigned int too, yes?