[PATCH v2 3/5] apple-gmux: Use GMSP acpi method for interrupt clear

[Orlando Chamberlain <orlandoch.dev@gmail.com>]

This is needed for interrupts to be cleared correctly on MMIO based
gmux's. It is untested if this helps/hinders other gmux types, so
currently this is only enabled for the MMIO gmux's.

There is also a "GMLV" acpi method, and the "GMSP" method can be called
with 1 as its argument, but the purposes of these aren't known and they
don't seem to be needed.

Signed-off-by: Orlando Chamberlain <orlandoch.dev@gmail.com>
---
v1->v2: Only enable this on MMIO gmux's
 drivers/platform/x86/apple-gmux.c | 30 +++++++++++++++++++++++++++++-
 1 file changed, 29 insertions(+), 1 deletion(-)

diff --git a/drivers/platform/x86/apple-gmux.c b/drivers/platform/x86/apple-gmux.c
index 36208e93d745..12a93fc49c36 100644
--- a/drivers/platform/x86/apple-gmux.c
+++ b/drivers/platform/x86/apple-gmux.c
@@ -76,6 +76,7 @@ struct apple_gmux_config {
 	enum vga_switcheroo_handler_flags_t handler_flags;
 	unsigned long resource_type;
 	bool read_version_as_u32;
+	bool use_acpi_gmsp;
 	char *name;
 };
 
@@ -488,6 +489,7 @@ static const struct apple_gmux_config apple_gmux_pio = {
 	.handler_flags = VGA_SWITCHEROO_CAN_SWITCH_DDC,
 	.resource_type = IORESOURCE_IO,
 	.read_version_as_u32 = false,
+	.use_acpi_gmsp = false,
 	.name = "classic"
 };
 
@@ -500,6 +502,7 @@ static const struct apple_gmux_config apple_gmux_index = {
 	.handler_flags = VGA_SWITCHEROO_NEEDS_EDP_CONFIG,
 	.resource_type = IORESOURCE_IO,
 	.read_version_as_u32 = true,
+	.use_acpi_gmsp = false,
 	.name = "indexed"
 };
 
@@ -511,8 +514,29 @@ static const struct apple_gmux_config apple_gmux_index = {
  * MCP79, on all following generations it's GPIO pin 6 of the Intel PCH.
  * The GPE merely signals that an interrupt occurred, the actual type of event
  * is identified by reading a gmux register.
+ *
+ * On MMIO gmux's, we also need to call the acpi method GMSP to properly clear
+ * interrupts.
  */
 
+static int gmux_call_acpi_gmsp(struct apple_gmux_data *gmux_data, int arg)
+{
+	acpi_status status = AE_OK;
+	union acpi_object arg0 = { ACPI_TYPE_INTEGER };
+	struct acpi_object_list arg_list = { 1, &arg0 };
+
+	arg0.integer.value = arg;
+
+	status = acpi_evaluate_object(gmux_data->dhandle, "GMSP", &arg_list, NULL);
+	if (ACPI_FAILURE(status)) {
+		pr_err("GMSP call failed: %s\n",
+		       acpi_format_exception(status));
+		return -ENODEV;
+	}
+
+	return 0;
+}
+
 static inline void gmux_disable_interrupts(struct apple_gmux_data *gmux_data)
 {
 	gmux_write8(gmux_data, GMUX_PORT_INTERRUPT_ENABLE,
@@ -536,7 +560,11 @@ static void gmux_clear_interrupts(struct apple_gmux_data *gmux_data)
 
 	/* to clear interrupts write back current status */
 	status = gmux_interrupt_get_status(gmux_data);
-	gmux_write8(gmux_data, GMUX_PORT_INTERRUPT_STATUS, status);
+	if (status) {
+		gmux_write8(gmux_data, GMUX_PORT_INTERRUPT_STATUS, status);
+		if (gmux_data->config->use_acpi_gmsp)
+			gmux_call_acpi_gmsp(gmux_data, 0);
+	}
 }
 
 static void gmux_notify_handler(acpi_handle device, u32 value, void *context)
-- 
2.39.1