Add force re-calibrate function supported for gen3 trackpad device,
it can be used through sysfs calibrate interface.
TEST=test on Chromebooks.

Signed-off-by: Dudley Du <dudley.duli...@gmail.com>
---
 drivers/input/mouse/cyapa_gen3.c | 58 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 58 insertions(+)

diff --git a/drivers/input/mouse/cyapa_gen3.c b/drivers/input/mouse/cyapa_gen3.c
index d3dbe0e..640b916 100644
--- a/drivers/input/mouse/cyapa_gen3.c
+++ b/drivers/input/mouse/cyapa_gen3.c
@@ -754,6 +754,63 @@ 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 = 20;  /* max recalibration timeout 2s. */
+       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;
+       }
+
+       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)
 {
@@ -1136,6 +1193,7 @@ const struct cyapa_dev_ops cyapa_gen3_ops = {
        .bl_deactivate = cyapa_gen3_bl_deactivate,
 
        .show_baseline = cyapa_gen3_show_baseline,
+       .calibrate_store = cyapa_gen3_do_calibrate,
 
        .state_parse = cyapa_gen3_state_parse,
        .operational_check = cyapa_gen3_do_operational_check,
-- 
1.9.1

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