CHROMIUM: Input: atmel_mxt_ts - add sysfs entry to read config checksum

Config checksum is returned in the T6 message at every boot, and when
the config changes.  Cache its value and add sysfs entry for userspace to
read it.

Signed-off-by: Daniel Kurtz <djkurtz@chromium.org>
BUG=chrome-os-partner:9103
TEST=cat /sys/bus/i2c/drivers/atmel_mxt_ts/2-004b/config_csum

Change-Id: Ic546d1671e9f6a3da598f06a31f76a6ca96ce235
Reviewed-on: https://gerrit.chromium.org/gerrit/20597
Commit-Ready: Daniel Kurtz <djkurtz@chromium.org>
Reviewed-by: Daniel Kurtz <djkurtz@chromium.org>
Tested-by: Daniel Kurtz <djkurtz@chromium.org>
Reviewed-by: Benson Leung <bleung@chromium.org>

diff --git a/drivers/input/touchscreen/atmel_mxt_ts.c b/drivers/input/touchscreen/atmel_mxt_ts.c
index c3a8530..aae8ea4 100644 (file)
--- a/drivers/input/touchscreen/atmel_mxt_ts.c
+++ b/drivers/input/touchscreen/atmel_mxt_ts.c
@@ -269,6 +269,8 @@ struct mxt_data {
        unsigned int max_x;
        unsigned int max_y;
 
+       u32 config_csum;
+
        /* Cached parameters from object table */
        u16 T5_address;
        u8 T6_reportid;
@@ -643,11 +645,11 @@ static int mxt_proc_messages(struct mxt_data *data, u8 count)
                        mxt_input_button(data, msg);
                        update_input = true;
                } else if (msg->reportid == data->T6_reportid) {
-                       unsigned csum = msg->message[1] |
-                                       (msg->message[2] << 8) |
-                                       (msg->message[3] << 16);
+                       data->config_csum = msg->message[1] |
+                                           (msg->message[2] << 8) |
+                                           (msg->message[3] << 16);
                        dev_info(dev, "Status: %02x Config Checksum: %06x\n",
-                                msg->message[0], csum);
+                                msg->message[0], data->config_csum);
                }
        }
 
@@ -965,7 +967,13 @@ static ssize_t mxt_calibrate_store(struct device *dev,
        return count;
 }
 
-/* Firmware Version is <Major>.<Minor>.<Build> */
+static ssize_t mxt_config_csum_show(struct device *dev,
+                                   struct device_attribute *attr, char *buf)
+{
+       struct mxt_data *data = dev_get_drvdata(dev);
+       return scnprintf(buf, PAGE_SIZE, "%06x\n", data->config_csum);
+}
+
 static ssize_t mxt_fw_version_show(struct device *dev,
                               struct device_attribute *attr, char *buf)
 {
@@ -1095,6 +1103,7 @@ static ssize_t mxt_update_fw_store(struct device *dev,
 
 static DEVICE_ATTR(backupnv, S_IWUSR, NULL, mxt_backupnv_store);
 static DEVICE_ATTR(calibrate, S_IWUSR, NULL, mxt_calibrate_store);
+static DEVICE_ATTR(config_csum, S_IRUGO, mxt_config_csum_show, NULL);
 static DEVICE_ATTR(fw_version, S_IRUGO, mxt_fw_version_show, NULL);
 static DEVICE_ATTR(hw_version, S_IRUGO, mxt_hw_version_show, NULL);
 static DEVICE_ATTR(object, S_IRUGO | S_IWUSR, mxt_object_show,
@@ -1104,6 +1113,7 @@ static DEVICE_ATTR(update_fw, S_IWUSR, NULL, mxt_update_fw_store);
 static struct attribute *mxt_attrs[] = {
        &dev_attr_backupnv.attr,
        &dev_attr_calibrate.attr,
+       &dev_attr_config_csum.attr,
        &dev_attr_fw_version.attr,
        &dev_attr_hw_version.attr,
        &dev_attr_object.attr,