--- /dev/null
+/*
+ * Copyright (c) 2012-2015 Synaptics Incorporated
+ * Copyright (C) 2016 Zodiac Inflight Innovations
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ */
+
+#include <linux/bitops.h>
+#include <linux/kernel.h>
+#include <linux/rmi.h>
+#include <linux/slab.h>
+#include "rmi_driver.h"
+
+#define F55_NAME               "rmi4_f55"
+
+/* F55 data offsets */
+#define F55_NUM_RX_OFFSET      0
+#define F55_NUM_TX_OFFSET      1
+#define F55_PHYS_CHAR_OFFSET   2
+
+/* Only read required query registers */
+#define F55_QUERY_LEN          3
+
+/* F55 capabilities */
+#define F55_CAP_SENSOR_ASSIGN  BIT(0)
+
+struct f55_data {
+       struct rmi_function *fn;
+
+       u8 qry[F55_QUERY_LEN];
+       u8 num_rx_electrodes;
+       u8 cfg_num_rx_electrodes;
+       u8 num_tx_electrodes;
+       u8 cfg_num_tx_electrodes;
+};
+
+static int rmi_f55_detect(struct rmi_function *fn)
+{
+       struct f55_data *f55;
+       int error;
+
+       f55 = dev_get_drvdata(&fn->dev);
+
+       error = rmi_read_block(fn->rmi_dev, fn->fd.query_base_addr,
+                              &f55->qry, sizeof(f55->qry));
+       if (error) {
+               dev_err(&fn->dev, "%s: Failed to query F55 properties\n",
+                       __func__);
+               return error;
+       }
+
+       f55->num_rx_electrodes = f55->qry[F55_NUM_RX_OFFSET];
+       f55->num_tx_electrodes = f55->qry[F55_NUM_TX_OFFSET];
+
+       f55->cfg_num_rx_electrodes = f55->num_rx_electrodes;
+       f55->cfg_num_tx_electrodes = f55->num_rx_electrodes;
+
+       if (f55->qry[F55_PHYS_CHAR_OFFSET] & F55_CAP_SENSOR_ASSIGN) {
+               int i, total;
+               u8 buf[256];
+
+               /*
+                * Calculate the number of enabled receive and transmit
+                * electrodes by reading F55:Ctrl1 (sensor receiver assignment)
+                * and F55:Ctrl2 (sensor transmitter assignment). The number of
+                * enabled electrodes is the sum of all field entries with a
+                * value other than 0xff.
+                */
+               error = rmi_read_block(fn->rmi_dev,
+                                      fn->fd.control_base_addr + 1,
+                                      buf, f55->num_rx_electrodes);
+               if (!error) {
+                       total = 0;
+                       for (i = 0; i < f55->num_rx_electrodes; i++) {
+                               if (buf[i] != 0xff)
+                                       total++;
+                       }
+                       f55->cfg_num_rx_electrodes = total;
+               }
+
+               error = rmi_read_block(fn->rmi_dev,
+                                      fn->fd.control_base_addr + 2,
+                                      buf, f55->num_tx_electrodes);
+               if (!error) {
+                       total = 0;
+                       for (i = 0; i < f55->num_tx_electrodes; i++) {
+                               if (buf[i] != 0xff)
+                                       total++;
+                       }
+                       f55->cfg_num_tx_electrodes = total;
+               }
+       }
+
+       rmi_dbg(RMI_DEBUG_FN, &fn->dev, "F55 num_rx_electrodes: %d (raw %d)\n",
+               f55->cfg_num_rx_electrodes, f55->num_rx_electrodes);
+       rmi_dbg(RMI_DEBUG_FN, &fn->dev, "F55 num_tx_electrodes: %d (raw %d)\n",
+               f55->cfg_num_tx_electrodes, f55->num_tx_electrodes);
+
+       return 0;
+}
+
+static int rmi_f55_probe(struct rmi_function *fn)
+{
+       struct f55_data *f55;
+
+       f55 = devm_kzalloc(&fn->dev, sizeof(struct f55_data), GFP_KERNEL);
+       if (!f55)
+               return -ENOMEM;
+
+       f55->fn = fn;
+       dev_set_drvdata(&fn->dev, f55);
+
+       return rmi_f55_detect(fn);
+}
+
+struct rmi_function_handler rmi_f55_handler = {
+       .driver = {
+               .name = F55_NAME,
+       },
+       .func = 0x55,
+       .probe = rmi_f55_probe,
+};