[RFC PATCH 5/9] apple-gmux: Use GMSP acpi method for interrupt clear

[Orlando Chamberlain]

This is needed for interrupts to be cleared correctly on MMIO based
gmux's. It is untested if this helps/hinders other gmux types, but I
have seen the GMSP method in the acpi tables of a MacBook with an
indexed gmux.

If this turns out to break support for older gmux's, this can instead
be only done on 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@xxxxxxxxx>
---
 drivers/platform/x86/apple-gmux.c | 26 +++++++++++++++++++++++++-
 1 file changed, 25 insertions(+), 1 deletion(-)

diff --git a/drivers/platform/x86/apple-gmux.c b/drivers/platform/x86/apple-gmux.c
index 760434a527c1..c605f036ea0b 100644
--- a/drivers/platform/x86/apple-gmux.c
+++ b/drivers/platform/x86/apple-gmux.c
@@ -494,8 +494,29 @@ 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. TODO: Do other types need this? Does this break other types?
  */
 
+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,
@@ -519,7 +540,10 @@ 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);
+		gmux_call_acpi_gmsp(gmux_data, 0);
+	}
 }
 
 static void gmux_notify_handler(acpi_handle device, u32 value, void *context)
-- 
2.39.1