Input: cyapa - add gen3 trackpad force re-calibrate support

Add force re-calibrate function support for gen3 trackpad device, it can be
used through sysfs calibrate interface.
Signed-off-by: Dudley Du <dudl@cypress.com>
Tested-by: Jeremiah Mahler <jmmahler@gmail.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/mouse/cyapa_gen3.c

@@ -783,6 +783,64 @@ static int cyapa_gen3_do_fw_update(struct cyapa *cyapa,
 	return 0;
 }
 
+static ssize_t cyapa_gen3_do_calibrate(struct device *dev,
+				     struct device_attribute *attr,
+				     const char *buf, size_t count)
+{
+	struct cyapa *cyapa = dev_get_drvdata(dev);
+	int tries;
+	int ret;
+
+	ret = cyapa_read_byte(cyapa, CYAPA_CMD_DEV_STATUS);
+	if (ret < 0) {
+		dev_err(dev, "Error reading dev status: %d\n", ret);
+		goto out;
+	}
+	if ((ret & CYAPA_DEV_NORMAL) != CYAPA_DEV_NORMAL) {
+		dev_warn(dev, "Trackpad device is busy, device state: 0x%02x\n",
+			 ret);
+		ret = -EAGAIN;
+		goto out;
+	}
+
+	ret = cyapa_write_byte(cyapa, CYAPA_CMD_SOFT_RESET,
+			       OP_RECALIBRATION_MASK);
+	if (ret < 0) {
+		dev_err(dev, "Failed to send calibrate command: %d\n",
+			ret);
+		goto out;
+	}
+
+	tries = 20;  /* max recalibration timeout 2s. */
+	do {
+		/*
+		 * For this recalibration, the max time will not exceed 2s.
+		 * The average time is approximately 500 - 700 ms, and we
+		 * will check the status every 100 - 200ms.
+		 */
+		usleep_range(100000, 200000);
+
+		ret = cyapa_read_byte(cyapa, CYAPA_CMD_DEV_STATUS);
+		if (ret < 0) {
+			dev_err(dev, "Error reading dev status: %d\n",
+				ret);
+			goto out;
+		}
+		if ((ret & CYAPA_DEV_NORMAL) == CYAPA_DEV_NORMAL)
+			break;
+	} while (--tries);
+
+	if (tries == 0) {
+		dev_err(dev, "Failed to calibrate. Timeout.\n");
+		ret = -ETIMEDOUT;
+		goto out;
+	}
+	dev_dbg(dev, "Calibration successful.\n");
+
+out:
+	return ret < 0 ? ret : count;
+}
+
 static ssize_t cyapa_gen3_show_baseline(struct device *dev,
 				   struct device_attribute *attr, char *buf)
 {
@@ -1175,6 +1233,7 @@ const struct cyapa_dev_ops cyapa_gen3_ops = {
 	.bl_initiate = cyapa_gen3_bl_initiate,
 
 	.show_baseline = cyapa_gen3_show_baseline,
+	.calibrate_store = cyapa_gen3_do_calibrate,
 
 	.initialize = cyapa_gen3_initialize,