Input: elo - add support for non-pressure-sensitive touchscreens

- Use the touch status bit rather than the pressure bits to
  distinguish a BTN_TOUCH event. Non-pressure-sensitive touchscreens
  always report full pressure
- Report ABS_PRESSURE information only if the touchscreen supports it

Signed-off-by: Shaun Jackman <sjackman@gmail.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

drivers/input/touchscreen/elo.c

@@ -23,6 +23,7 @@
 #include <linux/input.h>
 #include <linux/serio.h>
 #include <linux/init.h>
+#include <linux/ctype.h>
 
 #define DRIVER_DESC	"Elo serial touchscreen driver"
 
@@ -36,9 +37,17 @@ MODULE_LICENSE("GPL");
 
 #define ELO_MAX_LENGTH		10
 
+#define ELO10_PACKET_LEN	8
+#define ELO10_TOUCH		0x03
+#define ELO10_PRESSURE		0x80
+
 #define ELO10_LEAD_BYTE		'U'
 
+#define ELO10_ID_CMD		'i'
+
 #define ELO10_TOUCH_PACKET	'T'
+#define ELO10_ACK_PACKET	'A'
+#define ELI10_ID_PACKET		'I'
 
 /*
  * Per-touchscreen data.
@@ -47,10 +56,14 @@ MODULE_LICENSE("GPL");
 struct elo {
 	struct input_dev *dev;
 	struct serio *serio;
+	struct mutex cmd_mutex;
+	struct completion cmd_done;
 	int id;
 	int idx;
+	unsigned char expected_packet;
 	unsigned char csum;
 	unsigned char data[ELO_MAX_LENGTH];
+	unsigned char response[ELO10_PACKET_LEN];
 	char phys[32];
 };
 
@@ -75,16 +88,29 @@ static void elo_process_data_10(struct elo *elo, unsigned char data, struct pt_r
 					 data, elo->csum);
 				break;
 			}
-			if (elo->data[1] != ELO10_TOUCH_PACKET) {
-				pr_debug(elo: "unexpected packet: 0x%02x\n", elo->data[1]);
+			if (elo->data[1] != elo->expected_packet) {
+				if (elo->data[1] != ELO10_TOUCH_PACKET)
+					pr_debug("elo: unexpected packet: 0x%02x\n",
+						 elo->data[1]);
 				break;
 			}
-			input_regs(dev, regs);
-			input_report_abs(dev, ABS_X, (elo->data[4] << 8) | elo->data[3]);
-			input_report_abs(dev, ABS_Y, (elo->data[6] << 8) | elo->data[5]);
-			input_report_abs(dev, ABS_PRESSURE, (elo->data[8] << 8) | elo->data[7]);
-			input_report_key(dev, BTN_TOUCH, elo->data[8] || elo->data[7]);
-			input_sync(dev);
+			if (likely(elo->data[1] == ELO10_TOUCH_PACKET)) {
+				input_regs(dev, regs);
+				input_report_abs(dev, ABS_X, (elo->data[4] << 8) | elo->data[3]);
+				input_report_abs(dev, ABS_Y, (elo->data[6] << 8) | elo->data[5]);
+				if (elo->data[2] & ELO10_PRESSURE)
+					input_report_abs(dev, ABS_PRESSURE,
+							(elo->data[8] << 8) | elo->data[7]);
+				input_report_key(dev, BTN_TOUCH, elo->data[2] & ELO10_TOUCH);
+				input_sync(dev);
+			} else if (elo->data[1] == ELO10_ACK_PACKET) {
+				if (elo->data[2] == '0')
+					elo->expected_packet = ELO10_TOUCH_PACKET;
+				complete(&elo->cmd_done);
+			} else {
+				memcpy(elo->response, &elo->data[1], ELO10_PACKET_LEN);
+				elo->expected_packet = ELO10_ACK_PACKET;
+			}
 			break;
 	}
 	elo->csum += data;
@@ -184,6 +210,68 @@ static irqreturn_t elo_interrupt(struct serio *serio,
 	return IRQ_HANDLED;
 }
 
+static int elo_command_10(struct elo *elo, unsigned char *packet)
+{
+	int rc = -1;
+	int i;
+	unsigned char csum = 0xaa + ELO10_LEAD_BYTE;
+
+	mutex_lock(&elo->cmd_mutex);
+
+	serio_pause_rx(elo->serio);
+	elo->expected_packet = toupper(packet[0]);
+	init_completion(&elo->cmd_done);
+	serio_continue_rx(elo->serio);
+
+	if (serio_write(elo->serio, ELO10_LEAD_BYTE))
+		goto out;
+
+	for (i = 0; i < ELO10_PACKET_LEN; i++) {
+		csum += packet[i];
+		if (serio_write(elo->serio, packet[i]))
+			goto out;
+	}
+
+	if (serio_write(elo->serio, csum))
+		goto out;
+
+	wait_for_completion_timeout(&elo->cmd_done, HZ);
+
+	if (elo->expected_packet == ELO10_TOUCH_PACKET) {
+		/* We are back in reporting mode, the command was ACKed */
+		memcpy(packet, elo->response, ELO10_PACKET_LEN);
+		rc = 0;
+	}
+
+ out:
+	mutex_unlock(&elo->cmd_mutex);
+	return rc;
+}
+
+static int elo_setup_10(struct elo *elo)
+{
+	static const char *elo_types[] = { "Accu", "Dura", "Intelli", "Carroll" };
+	struct input_dev *dev = elo->dev;
+	unsigned char packet[ELO10_PACKET_LEN] = { ELO10_ID_CMD };
+
+	if (elo_command_10(elo, packet))
+		return -1;
+
+	dev->id.version = (packet[5] << 8) | packet[4];
+
+	input_set_abs_params(dev, ABS_X, 96, 4000, 0, 0);
+	input_set_abs_params(dev, ABS_Y, 96, 4000, 0, 0);
+	if (packet[3] & ELO10_PRESSURE)
+		input_set_abs_params(dev, ABS_PRESSURE, 0, 255, 0, 0);
+
+	printk(KERN_INFO "elo: %sTouch touchscreen, fw: %02x.%02x, "
+		"features: %x02x, controller: 0x%02x\n",
+		elo_types[(packet[1] -'0') & 0x03],
+		packet[5], packet[4], packet[3], packet[7]);
+
+	return 0;
+}
+
 /*
  * elo_disconnect() is the opposite of elo_connect()
  */
@@ -222,6 +310,9 @@ static int elo_connect(struct serio *serio, struct serio_driver *drv)
 	elo->serio = serio;
 	elo->id = serio->id.id;
 	elo->dev = input_dev;
+	elo->expected_packet = ELO10_TOUCH_PACKET;
+	mutex_init(&elo->cmd_mutex);
+	init_completion(&elo->cmd_done);
 	snprintf(elo->phys, sizeof(elo->phys), "%s/input0", serio->phys);
 
 	input_dev->private = elo;
@@ -236,12 +327,17 @@ static int elo_connect(struct serio *serio, struct serio_driver *drv)
 	input_dev->evbit[0] = BIT(EV_KEY) | BIT(EV_ABS);
 	input_dev->keybit[LONG(BTN_TOUCH)] = BIT(BTN_TOUCH);
 
+	serio_set_drvdata(serio, elo);
+	err = serio_open(serio, drv);
+	if (err)
+		goto fail2;
+
 	switch (elo->id) {
 
 		case 0: /* 10-byte protocol */
-			input_set_abs_params(input_dev, ABS_X, 96, 4000, 0, 0);
-			input_set_abs_params(input_dev, ABS_Y, 96, 4000, 0, 0);
-			input_set_abs_params(input_dev, ABS_PRESSURE, 0, 255, 0, 0);
+			if (elo_setup_10(elo))
+				goto fail3;
+
 			break;
 
 		case 1: /* 6-byte protocol */
@@ -258,12 +354,6 @@ static int elo_connect(struct serio *serio, struct serio_driver *drv)
 			break;
 	}
 
-	serio_set_drvdata(serio, elo);
-
-	err = serio_open(serio, drv);
-	if (err)
-		goto fail2;
-
 	err = input_register_device(elo->dev);
 	if (err)
 		goto fail3;