ideapad: add ACPI helpers

There are two methods under VPC2004 which is used to access VDAT/VCMD of EC
register. Add helpers for read and write these two registers.

And add read_method_int for reading the return value from ACPI methods which
requires no parameter.
Signed-off-by: NIke Panhc <ike.pan@canonical.com>
Signed-off-by: NMatthew Garrett <mjg@redhat.com>

drivers/platform/x86/ideapad_acpi.c

@@ -49,6 +49,115 @@ static struct {
 	{ "ideapad_killsw",	RFKILL_TYPE_WLAN }
 };
 
+/*
+ * ACPI Helpers
+ */
+#define IDEAPAD_EC_TIMEOUT (100) /* in ms */
+
+static int read_method_int(acpi_handle handle, const char *method, int *val)
+{
+	acpi_status status;
+	unsigned long long result;
+
+	status = acpi_evaluate_integer(handle, (char *)method, NULL, &result);
+	if (ACPI_FAILURE(status)) {
+		*val = -1;
+		return -1;
+	} else {
+		*val = result;
+		return 0;
+	}
+}
+
+static int method_vpcr(acpi_handle handle, int cmd, int *ret)
+{
+	acpi_status status;
+	unsigned long long result;
+	struct acpi_object_list params;
+	union acpi_object in_obj;
+
+	params.count = 1;
+	params.pointer = &in_obj;
+	in_obj.type = ACPI_TYPE_INTEGER;
+	in_obj.integer.value = cmd;
+
+	status = acpi_evaluate_integer(handle, "VPCR", &params, &result);
+
+	if (ACPI_FAILURE(status)) {
+		*ret = -1;
+		return -1;
+	} else {
+		*ret = result;
+		return 0;
+	}
+}
+
+static int method_vpcw(acpi_handle handle, int cmd, int data)
+{
+	struct acpi_object_list params;
+	union acpi_object in_obj[2];
+	acpi_status status;
+
+	params.count = 2;
+	params.pointer = in_obj;
+	in_obj[0].type = ACPI_TYPE_INTEGER;
+	in_obj[0].integer.value = cmd;
+	in_obj[1].type = ACPI_TYPE_INTEGER;
+	in_obj[1].integer.value = data;
+
+	status = acpi_evaluate_object(handle, "VPCW", &params, NULL);
+	if (status != AE_OK)
+		return -1;
+	return 0;
+}
+
+static int read_ec_data(acpi_handle handle, int cmd, unsigned long *data)
+{
+	int val;
+	unsigned long int end_jiffies;
+
+	if (method_vpcw(handle, 1, cmd))
+		return -1;
+
+	for (end_jiffies = jiffies+(HZ)*IDEAPAD_EC_TIMEOUT/1000+1;
+	     time_before(jiffies, end_jiffies);) {
+		schedule();
+		if (method_vpcr(handle, 1, &val))
+			return -1;
+		if (val == 0) {
+			if (method_vpcr(handle, 0, &val))
+				return -1;
+			*data = val;
+			return 0;
+		}
+	}
+	pr_err("timeout in read_ec_cmd\n");
+	return -1;
+}
+
+static int write_ec_cmd(acpi_handle handle, int cmd, unsigned long data)
+{
+	int val;
+	unsigned long int end_jiffies;
+
+	if (method_vpcw(handle, 0, data))
+		return -1;
+	if (method_vpcw(handle, 1, cmd))
+		return -1;
+
+	for (end_jiffies = jiffies+(HZ)*IDEAPAD_EC_TIMEOUT/1000+1;
+	     time_before(jiffies, end_jiffies);) {
+		schedule();
+		if (method_vpcr(handle, 1, &val))
+			return -1;
+		if (val == 0)
+			return 0;
+	}
+	pr_err("timeout in write_ec_cmd\n");
+	return -1;
+}
+/* the above is ACPI helpers */
+
 static int ideapad_dev_exists(int device)
 {
 	acpi_status status;