[PATCH 01/13] mfd: cros_ec: Add sensor_count and make check_features public

[Gwendal Grignou <gwendal@chromium.org>]

Add a new function to return the number of MEMS sensors available in a
ChromeOS Embedded Controller.
It uses MOTIONSENSE_CMD_DUMP if available or a specific memory map ACPI
registers to find out.

Also, make check_features public as it can be useful for other drivers
to know whant the Embedded Controller supports.

Signed-off-by: Gwendal Grignou <gwendal@chromium.org>
---
 drivers/mfd/cros_ec_dev.c   | 61 ++++++++++++++++++++++++++++++++++++-
 include/linux/mfd/cros_ec.h | 17 +++++++++++
 2 files changed, 77 insertions(+), 1 deletion(-)

diff --git a/drivers/mfd/cros_ec_dev.c b/drivers/mfd/cros_ec_dev.c
index 6e6dfd6c1871..3be80183ccaa 100644
--- a/drivers/mfd/cros_ec_dev.c
+++ b/drivers/mfd/cros_ec_dev.c
@@ -112,7 +112,7 @@ static const struct mfd_cell cros_ec_vbc_cells[] = {
 	{ .name = "cros-ec-vbc", }
 };
 
-static int cros_ec_check_features(struct cros_ec_dev *ec, int feature)
+int cros_ec_check_features(struct cros_ec_dev *ec, int feature)
 {
 	struct cros_ec_command *msg;
 	int ret;
@@ -143,12 +143,71 @@ static int cros_ec_check_features(struct cros_ec_dev *ec, int feature)
 
 	return ec->features[feature / 32] & EC_FEATURE_MASK_0(feature);
 }
+EXPORT_SYMBOL_GPL(cros_ec_check_features);
 
 static void cros_ec_class_release(struct device *dev)
 {
 	kfree(to_cros_ec_dev(dev));
 }
 
+int cros_ec_get_sensor_count(struct cros_ec_dev *ec)
+{
+	/*
+	 * Issue a command to get the number of sensor reported.
+	 * If not supported, check for legacy mode.
+	 */
+	int ret, sensor_count;
+	struct ec_params_motion_sense *params;
+	struct ec_response_motion_sense *resp;
+	struct cros_ec_command *msg;
+	struct cros_ec_device *ec_dev = ec->ec_dev;
+	u8 status;
+
+	msg = kzalloc(sizeof(struct cros_ec_command) +
+			max(sizeof(*params), sizeof(*resp)), GFP_KERNEL);
+	if (msg == NULL)
+		return -ENOMEM;
+
+	msg->version = 1;
+	msg->command = EC_CMD_MOTION_SENSE_CMD + ec->cmd_offset;
+	msg->outsize = sizeof(*params);
+	msg->insize = sizeof(*resp);
+
+	params = (struct ec_params_motion_sense *)msg->data;
+	params->cmd = MOTIONSENSE_CMD_DUMP;
+
+	ret = cros_ec_cmd_xfer(ec->ec_dev, msg);
+	if (ret < 0) {
+		sensor_count = ret;
+	} else if (msg->result != EC_RES_SUCCESS) {
+		sensor_count = -EPROTO;
+	} else {
+		resp = (struct ec_response_motion_sense *)msg->data;
+		sensor_count = resp->dump.sensor_count;
+	}
+	kfree(msg);
+
+	/*
+	 * Check legacy mode: Let's find out if sensors are accessible
+	 * via LPC interface.
+	 */
+	if (sensor_count == -EPROTO &&
+	    ec->cmd_offset == 0 &&
+	    ec_dev->cmd_readmem) {
+		ret = ec_dev->cmd_readmem(ec_dev, EC_MEMMAP_ACC_STATUS,
+				1, &status);
+		if ((ret >= 0) &&
+		    (status & EC_MEMMAP_ACC_STATUS_PRESENCE_BIT)) {
+			/*
+			 * We have 2 sensors, one in the lid, one in the base.
+			 */
+			sensor_count = 2;
+		}
+	}
+	return sensor_count;
+}
+EXPORT_SYMBOL_GPL(cros_ec_get_sensor_count);
+
 static void cros_ec_sensors_register(struct cros_ec_dev *ec)
 {
 	/*
diff --git a/include/linux/mfd/cros_ec.h b/include/linux/mfd/cros_ec.h
index 61c2875c2a40..578e0bbcafdc 100644
--- a/include/linux/mfd/cros_ec.h
+++ b/include/linux/mfd/cros_ec.h
@@ -32,4 +32,21 @@ struct cros_ec_dev {
 
 #define to_cros_ec_dev(dev)  container_of(dev, struct cros_ec_dev, class_dev)
 
+/**
+ * cros_ec_check_features - Test for the presence of EC features
+ *
+ * Call this function to test whether the ChromeOS EC supports a feature.
+ *
+ * @ec_dev: EC device
+ * @msg: One of ec_feature_code values
+ * @return: 1 if supported, 0 if not
+ */
+int cros_ec_check_features(struct cros_ec_dev *ec, int feature);
+
+/*
+ * Return the number of MEMS sensors supported.
+ * Return < 0 in case of error.
+ */
+int cros_ec_get_sensor_count(struct cros_ec_dev *ec);
+
 #endif /* __LINUX_MFD_CROS_EC_H */
-- 
2.23.0.351.gc4317032e6-goog