Re: [PATCH v8 15/21] ARM64 / ACPI: Introduce ACPI_IRQ_MODEL_GIC and register device's gsi

From: Hanjun Guo
Date: Mon Feb 09 2015 - 01:53:44 EST


On 2015å02æ09æ 14:34, Will Deacon wrote:
On Mon, Feb 02, 2015 at 12:45:43PM +0000, Hanjun Guo wrote:
Introduce ACPI_IRQ_MODEL_GIC which is needed for ARM64 as GIC is
used, and then register device's gsi with the core IRQ subsystem.

acpi_register_gsi() is similar to DT based irq_of_parse_and_map(),
since gsi is unique in the system, so use hwirq number directly
for the mapping.

We are going to implement stacked domains when GICv2m, GICv3, ITS
support are added.

CC: Marc Zyngier <marc.zyngier@xxxxxxx>
Originally-by: Amit Daniel Kachhap <amit.daniel@xxxxxxxxxxx>
Tested-by: Suravee Suthikulpanit <Suravee.Suthikulpanit@xxxxxxx>
Tested-by: Yijing Wang <wangyijing@xxxxxxxxxx>
Tested-by: Mark Langsdorf <mlangsdo@xxxxxxxxxx>
Tested-by: Jon Masters <jcm@xxxxxxxxxx>
Tested-by: Timur Tabi <timur@xxxxxxxxxxxxxx>
Signed-off-by: Hanjun Guo <hanjun.guo@xxxxxxxxxx>
---
arch/arm64/kernel/acpi.c | 73 ++++++++++++++++++++++++++++++++++++++++++++++++
drivers/acpi/bus.c | 3 ++
include/linux/acpi.h | 1 +
3 files changed, 77 insertions(+)

diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c
index f80caef..f86a982 100644
--- a/arch/arm64/kernel/acpi.c
+++ b/arch/arm64/kernel/acpi.c
@@ -38,6 +38,12 @@ EXPORT_SYMBOL(acpi_pci_disabled);
static int enabled_cpus; /* Processors (GICC) with enabled flag in MADT */

/*
+ * Since we're on ARM, the default interrupt routing model
+ * clearly has to be GIC.
+ */
+enum acpi_irq_model_id acpi_irq_model = ACPI_IRQ_MODEL_GIC;
+
+/*
* __acpi_map_table() will be called before page_init(), so early_ioremap()
* or early_memremap() should be called here to for ACPI table mapping.
*/
@@ -185,6 +191,73 @@ void __init acpi_init_cpus(void)
pr_info("%d CPUs enabled, %d CPUs total\n", enabled_cpus, total_cpus);
}

+int acpi_gsi_to_irq(u32 gsi, unsigned int *irq)
+{
+ *irq = irq_find_mapping(NULL, gsi);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(acpi_gsi_to_irq);
+
+/*
+ * success: return IRQ number (>0)
+ * failure: return =< 0
+ */
+int acpi_register_gsi(struct device *dev, u32 gsi, int trigger, int polarity)
+{
+ unsigned int irq;
+ unsigned int irq_type;
+
+ /*
+ * ACPI have no bindings to indicate SPI or PPI, so we
+ * use different mappings from DT in ACPI.
+ *
+ * For FDT
+ * PPI interrupt: in the range [0, 15];
+ * SPI interrupt: in the range [0, 987];
+ *
+ * For ACPI, GSI should be unique so using
+ * the hwirq directly for the mapping:
+ * PPI interrupt: in the range [16, 31];
+ * SPI interrupt: in the range [32, 1019];
+ */
+
+ if (trigger == ACPI_EDGE_SENSITIVE &&
+ polarity == ACPI_ACTIVE_LOW)
+ irq_type = IRQ_TYPE_EDGE_FALLING;
+ else if (trigger == ACPI_EDGE_SENSITIVE &&
+ polarity == ACPI_ACTIVE_HIGH)
+ irq_type = IRQ_TYPE_EDGE_RISING;
+ else if (trigger == ACPI_LEVEL_SENSITIVE &&
+ polarity == ACPI_ACTIVE_LOW)
+ irq_type = IRQ_TYPE_LEVEL_LOW;
+ else if (trigger == ACPI_LEVEL_SENSITIVE &&
+ polarity == ACPI_ACTIVE_HIGH)
+ irq_type = IRQ_TYPE_LEVEL_HIGH;
+ else
+ irq_type = IRQ_TYPE_NONE;
+
+ /*
+ * Since only one GIC is supported in ACPI 5.0, we can
+ * create mapping refer to the default domain
+ */
+ irq = irq_create_mapping(NULL, gsi);
+ if (!irq)
+ return irq;
+
+ /* Set irq type if specified and different than the current one */
+ if (irq_type != IRQ_TYPE_NONE &&
+ irq_type != irq_get_trigger_type(irq))
+ irq_set_irq_type(irq, irq_type);
+ return irq;
+}
+EXPORT_SYMBOL_GPL(acpi_register_gsi);
+
+void acpi_unregister_gsi(u32 gsi)
+{
+}
+EXPORT_SYMBOL_GPL(acpi_unregister_gsi);
+
static int __init acpi_parse_fadt(struct acpi_table_header *table)
{
struct acpi_table_fadt *fadt = (struct acpi_table_fadt *)table;

Does this code *have* to sit under arch/arm64? I can't see anything
architecture-specific about it and the bulk of the functions map directly
onto irq domain callbacks. I know that the answer is probably "we can fix
that in the future", but it doesn't seem like a huge amount of effort to
get the right abstractions in place from the beginning so that we don't
have to churn this stuff later on.

Do you mean move acpi_register_gsi()/acpi_unregister_gsi() to irqdomain
related file?

Since x86 and IA64 have their arch specific acpi_register_gsi()
/acpi_unregister_gsi(), we will got compile errors on x86 and IA64
platforms.

Thanks
Hanjun
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