acpi: Support writing a GPIO

Allowing writing out a reference to a GPIO within the ACPI output. This
can be used by ACPI code to access a GPIO at runtime.

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>

3 files changed, 83 insertions, 0 deletions

diff --git a/include/acpi/acpi_dp.h b/include/acpi/acpi_dp.h
index a82330856a..b89e0b8c49 100644
--- a/include/acpi/acpi_dp.h
+++ b/include/acpi/acpi_dp.h
@@ -11,6 +11,8 @@
 
 struct acpi_ctx;
 
+#include <acpi/acpi_device.h>
+
 /*
  * Writing Device Properties objects via _DSD
  *
@@ -204,6 +206,24 @@ struct acpi_dp *acpi_dp_add_child(struct acpi_dp *dp, const char *name,
 				  struct acpi_dp *child);
 
 /**
+ * acpi_dp_add_gpio() - Add a GPIO to a list of Device Properties
+ *
+ * A new node is added to the end of the property list of @dp, with the
+ * GPIO properties added to the the new node
+ *
+ * @dp: Table to add this property to
+ * @name: Name of property
+ * @ref: Reference to device with a _CRS containing GpioIO or GpioInt
+ * @index: Index of the GPIO resource in _CRS starting from zero
+ * @pin: Pin in the GPIO resource, typically zero
+ * @polarity: GPIO polarity. Note that ACPI_IRQ_ACTIVE_BOTH is not supported
+ * @return pointer to new node, or NULL if out of memory
+ */
+struct acpi_dp *acpi_dp_add_gpio(struct acpi_dp *dp, const char *name,
+				 const char *ref, int index, int pin,
+				 enum acpi_irq_polarity polarity);
+
+/**
  * acpi_dp_write() - Write Device Property hierarchy and clean up resources
  *
  * This writes the table using acpigen and then frees it
diff --git a/lib/acpi/acpi_dp.c b/lib/acpi/acpi_dp.c
index 32528e1ec4..e8de5651c8 100644
--- a/lib/acpi/acpi_dp.c
+++ b/lib/acpi/acpi_dp.c
@@ -321,3 +321,26 @@ struct acpi_dp *acpi_dp_add_integer_array(struct acpi_dp *dp, const char *name,
 
 	return dp_array;
 }
+
+struct acpi_dp *acpi_dp_add_gpio(struct acpi_dp *dp, const char *name,
+				 const char *ref, int index, int pin,
+				 enum acpi_irq_polarity polarity)
+{
+	struct acpi_dp *gpio;
+
+	assert(dp);
+	gpio = acpi_dp_new_table(name);
+	if (!gpio)
+		return NULL;
+
+	if (!acpi_dp_add_reference(gpio, NULL, ref) ||
+	    !acpi_dp_add_integer(gpio, NULL, index) ||
+	    !acpi_dp_add_integer(gpio, NULL, pin) ||
+	    !acpi_dp_add_integer(gpio, NULL, polarity == ACPI_IRQ_ACTIVE_LOW))
+		return NULL;
+
+	if (!acpi_dp_add_array(dp, gpio))
+		return NULL;
+
+	return gpio;
+}
diff --git a/test/dm/acpi_dp.c b/test/dm/acpi_dp.c
index 28696aaff6..8b812260b1 100644
--- a/test/dm/acpi_dp.c
+++ b/test/dm/acpi_dp.c
@@ -383,3 +383,43 @@ static int dm_test_acpi_dp_child(struct unit_test_state *uts)
 	return 0;
 }
 DM_TEST(dm_test_acpi_dp_child, 0);
+
+/* Test emitting a GPIO */
+static int dm_test_acpi_dp_gpio(struct unit_test_state *uts)
+{
+	struct acpi_ctx *ctx;
+	struct acpi_dp *dp;
+	u8 *ptr, *pptr;
+
+	ut_assertok(alloc_context(&ctx));
+
+	dp = acpi_dp_new_table("FRED");
+	ut_assertnonnull(dp);
+
+	/* Try a few different parameters */
+	ut_assertnonnull(acpi_dp_add_gpio(dp, "reset", TEST_REF, 0x23, 0x24,
+					  ACPI_IRQ_ACTIVE_HIGH));
+	ut_assertnonnull(acpi_dp_add_gpio(dp, "allow", TEST_REF, 0, 0,
+					  ACPI_IRQ_ACTIVE_LOW));
+
+	ptr = acpigen_get_current(ctx);
+	ut_assertok(acpi_dp_write(ctx, dp));
+	ut_asserteq(0x6e, acpigen_get_current(ctx) - ptr);
+
+	pptr = ptr + 0x2c; //0x3a;
+	ut_asserteq_str("reset", (char *)pptr);
+	ut_asserteq_strn(EXPECT_REF, (char *)pptr + 0xe);
+	ut_asserteq(0x23, pptr[0x1b]);
+	ut_asserteq(0x24, pptr[0x1d]);
+	ut_asserteq(ZERO_OP, pptr[0x1e]);
+
+	pptr = ptr + 0x51;
+	ut_asserteq_str("allow", (char *)pptr);
+	ut_asserteq_strn(EXPECT_REF, (char *)pptr + 0xe);
+	ut_asserteq(ZERO_OP, pptr[0x1a]);
+	ut_asserteq(ZERO_OP, pptr[0x1b]);
+	ut_asserteq(ONE_OP, pptr[0x1c]);
+
+	return 0;
+}
+DM_TEST(dm_test_acpi_dp_gpio, 0);