acpi: Support generation of interrupt descriptor

Add a function to write an interrupt descriptor to the generated ACPI
code.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Wolfgang Wallner <wolfgang.wallner@br-automation.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

include/acpi/acpi_device.h

@@ -11,6 +11,8 @@
 
 #include <linux/bitops.h>
 
+struct acpi_ctx;
+struct irq;
 struct udevice;
 
 /* ACPI descriptor values for common descriptors: SERIAL_BUS means I2C */
@@ -128,4 +130,17 @@ int acpi_device_scope(const struct udevice *dev, char *scope, int maxlen);
  */
 enum acpi_dev_status acpi_device_status(const struct udevice *dev);
 
+/**
+ * acpi_device_write_interrupt_irq() - Write an interrupt descriptor
+ *
+ * This writes an ACPI interrupt descriptor for the given interrupt, converting
+ * fields as needed.
+ *
+ * @ctx: ACPI context pointer
+ * @req_irq: Interrupt to output
+ * @return IRQ pin number if OK, -ve on error
+ */
+int acpi_device_write_interrupt_irq(struct acpi_ctx *ctx,
+				    const struct irq *req_irq);
+
 #endif

lib/acpi/acpi_device.c

@@ -8,8 +8,10 @@
 
 #include <common.h>
 #include <dm.h>
+#include <irq.h>
 #include <log.h>
 #include <acpi/acpi_device.h>
+#include <acpi/acpigen.h>
 #include <dm/acpi.h>
 
 /**
@@ -86,3 +88,120 @@ enum acpi_dev_status acpi_device_status(const struct udevice *dev)
 {
 	return ACPI_DSTATUS_ALL_ON;
 }
+
+/**
+ * largeres_write_len_f() - Write a placeholder word value
+ *
+ * Write a forward length for a large resource (2 bytes)
+ *
+ * @return pointer to the zero word (for fixing up later)
+ */
+static void *largeres_write_len_f(struct acpi_ctx *ctx)
+{
+	u8 *p = acpigen_get_current(ctx);
+
+	acpigen_emit_word(ctx, 0);
+
+	return p;
+}
+
+/**
+ * largeres_fill_from_len() - Fill in a length value
+ *
+ * This calculated the number of bytes since the provided @start and writes it
+ * to @ptr, which was previous returned by largeres_write_len_f().
+ *
+ * @ptr: Word to update
+ * @start: Start address to count from to calculated the length
+ */
+static void largeres_fill_from_len(struct acpi_ctx *ctx, char *ptr, u8 *start)
+{
+	u16 len = acpigen_get_current(ctx) - start;
+
+	ptr[0] = len & 0xff;
+	ptr[1] = (len >> 8) & 0xff;
+}
+
+/**
+ * largeres_fill_len() - Fill in a length value, excluding the length itself
+ *
+ * Fill in the length field with the value calculated from after the 16bit
+ * field to acpigen current. This is useful since the length value does not
+ * include the length field itself.
+ *
+ * This calls acpi_device_largeres_fill_len() passing @ptr + 2 as @start
+ *
+ * @ptr: Word to update.
+ */
+static void largeres_fill_len(struct acpi_ctx *ctx, void *ptr)
+{
+	largeres_fill_from_len(ctx, ptr, ptr + sizeof(u16));
+}
+
+/* ACPI 6.3 section 6.4.3.6: Extended Interrupt Descriptor */
+static int acpi_device_write_interrupt(struct acpi_ctx *ctx,
+				       const struct acpi_irq *irq)
+{
+	void *desc_length;
+	u8 flags;
+
+	if (!irq->pin)
+		return -ENOENT;
+
+	/* This is supported by GpioInt() but not Interrupt() */
+	if (irq->polarity == ACPI_IRQ_ACTIVE_BOTH)
+		return -EINVAL;
+
+	/* Byte 0: Descriptor Type */
+	acpigen_emit_byte(ctx, ACPI_DESCRIPTOR_INTERRUPT);
+
+	/* Byte 1-2: Length (filled in later) */
+	desc_length = largeres_write_len_f(ctx);
+
+	/*
+	 * Byte 3: Flags
+	 *  [7:5]: Reserved
+	 *    [4]: Wake     (0=NO_WAKE   1=WAKE)
+	 *    [3]: Sharing  (0=EXCLUSIVE 1=SHARED)
+	 *    [2]: Polarity (0=HIGH      1=LOW)
+	 *    [1]: Mode     (0=LEVEL     1=EDGE)
+	 *    [0]: Resource (0=PRODUCER  1=CONSUMER)
+	 */
+	flags = BIT(0); /* ResourceConsumer */
+	if (irq->mode == ACPI_IRQ_EDGE_TRIGGERED)
+		flags |= BIT(1);
+	if (irq->polarity == ACPI_IRQ_ACTIVE_LOW)
+		flags |= BIT(2);
+	if (irq->shared == ACPI_IRQ_SHARED)
+		flags |= BIT(3);
+	if (irq->wake == ACPI_IRQ_WAKE)
+		flags |= BIT(4);
+	acpigen_emit_byte(ctx, flags);
+
+	/* Byte 4: Interrupt Table Entry Count */
+	acpigen_emit_byte(ctx, 1);
+
+	/* Byte 5-8: Interrupt Number */
+	acpigen_emit_dword(ctx, irq->pin);
+
+	/* Fill in Descriptor Length (account for len word) */
+	largeres_fill_len(ctx, desc_length);
+
+	return 0;
+}
+
+int acpi_device_write_interrupt_irq(struct acpi_ctx *ctx,
+				    const struct irq *req_irq)
+{
+	struct acpi_irq irq;
+	int ret;
+
+	ret = irq_get_acpi(req_irq, &irq);
+	if (ret)
+		return log_msg_ret("get", ret);
+	ret = acpi_device_write_interrupt(ctx, &irq);
+	if (ret)
+		return log_msg_ret("write", ret);
+
+	return 0;
+}

test/dm/acpigen.c

@@ -8,8 +8,10 @@
 
 #include <common.h>
 #include <dm.h>
+#include <irq.h>
 #include <malloc.h>
 #include <acpi/acpigen.h>
+#include <acpi/acpi_device.h>
 #include <asm/unaligned.h>
 #include <dm/acpi.h>
 #include <dm/test.h>
@@ -70,3 +72,33 @@ static int dm_test_acpi_emit_simple(struct unit_test_state *uts)
 	return 0;
 }
 DM_TEST(dm_test_acpi_emit_simple, 0);
+
+/* Test emitting an interrupt descriptor */
+static int dm_test_acpi_interrupt(struct unit_test_state *uts)
+{
+	struct acpi_ctx *ctx;
+	struct udevice *dev;
+	struct irq irq;
+	u8 *ptr;
+
+	ut_assertok(alloc_context(&ctx));
+
+	ptr = acpigen_get_current(ctx);
+
+	ut_assertok(uclass_first_device_err(UCLASS_TEST_FDT, &dev));
+	ut_assertok(irq_get_by_index(dev, 0, &irq));
+
+	/* See a-test, property interrupts-extended in the device tree */
+	ut_asserteq(3, acpi_device_write_interrupt_irq(ctx, &irq));
+	ut_asserteq(9, acpigen_get_current(ctx) - ptr);
+	ut_asserteq(ACPI_DESCRIPTOR_INTERRUPT, ptr[0]);
+	ut_asserteq(6, get_unaligned((u16 *)(ptr + 1)));
+	ut_asserteq(0x19, ptr[3]);
+	ut_asserteq(1, ptr[4]);
+	ut_asserteq(3, get_unaligned((u32 *)(ptr + 5)));
+
+	free_context(&ctx);
+
+	return 0;
+}
+DM_TEST(dm_test_acpi_interrupt, DM_TESTF_SCAN_PDATA | DM_TESTF_SCAN_FDT);