Input: psmouse - add a custom serio protocol to send extra information

The tracksticks on the Lenovo thinkpads have their buttons connected
through the touchpad device. We already fixed that in synaptics.c, but
when we switch the device into RMI4 mode to have proper support, the
pass-through functionality can't deal with them easily.

We add a new PS/2 flag and protocol designed for psmouse.  The RMI4 F03
pass-through can then emit a special set of commands to notify psmouse the
state of the buttons.

This patch implements the protocol in psmouse, while an other will
do the same for rmi4-f03.
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/mouse/psmouse-base.c

@@ -127,6 +127,13 @@ struct psmouse_protocol {
 	int (*init)(struct psmouse *);
 };
 
+static void psmouse_report_standard_buttons(struct input_dev *dev, u8 buttons)
+{
+	input_report_key(dev, BTN_LEFT,   buttons & BIT(0));
+	input_report_key(dev, BTN_MIDDLE, buttons & BIT(2));
+	input_report_key(dev, BTN_RIGHT,  buttons & BIT(1));
+}
+
 /*
  * psmouse_process_byte() analyzes the PS/2 data stream and reports
  * relevant events to the input module once full packet has arrived.
@@ -199,9 +206,8 @@ psmouse_ret_t psmouse_process_byte(struct psmouse *psmouse)
 	}
 
 	/* Generic PS/2 Mouse */
-	input_report_key(dev, BTN_LEFT,    packet[0]       & 1);
-	input_report_key(dev, BTN_MIDDLE, (packet[0] >> 2) & 1);
-	input_report_key(dev, BTN_RIGHT,  (packet[0] >> 1) & 1);
+	psmouse_report_standard_buttons(dev,
+					packet[0] | psmouse->extra_buttons);
 
 	input_report_rel(dev, REL_X, packet[1] ? (int) packet[1] - (int) ((packet[0] << 4) & 0x100) : 0);
 	input_report_rel(dev, REL_Y, packet[2] ? (int) ((packet[0] << 3) & 0x100) - (int) packet[2] : 0);
@@ -282,6 +288,30 @@ static int psmouse_handle_byte(struct psmouse *psmouse)
 	return 0;
 }
 
+static void psmouse_handle_oob_data(struct psmouse *psmouse, u8 data)
+{
+	switch (psmouse->oob_data_type) {
+	case PSMOUSE_OOB_NONE:
+		psmouse->oob_data_type = data;
+		break;
+
+	case PSMOUSE_OOB_EXTRA_BTNS:
+		psmouse_report_standard_buttons(psmouse->dev, data);
+		input_sync(psmouse->dev);
+
+		psmouse->extra_buttons = data;
+		psmouse->oob_data_type = PSMOUSE_OOB_NONE;
+		break;
+
+	default:
+		psmouse_warn(psmouse,
+			     "unknown OOB_DATA type: 0x%02x\n",
+			     psmouse->oob_data_type);
+		psmouse->oob_data_type = PSMOUSE_OOB_NONE;
+		break;
+	}
+}
+
 /*
  * psmouse_interrupt() handles incoming characters, either passing them
  * for normal processing or gathering them as command response.
@@ -306,6 +336,11 @@ static irqreturn_t psmouse_interrupt(struct serio *serio,
 		goto out;
 	}
 
+	if (flags & SERIO_OOB_DATA) {
+		psmouse_handle_oob_data(psmouse, data);
+		goto out;
+	}
+
 	if (unlikely(psmouse->ps2dev.flags & PS2_FLAG_ACK))
 		if  (ps2_handle_ack(&psmouse->ps2dev, data))
 			goto out;

drivers/input/mouse/psmouse.h

 #ifndef _PSMOUSE_H
 #define _PSMOUSE_H
 
+#define PSMOUSE_OOB_NONE	0x00
+#define PSMOUSE_OOB_EXTRA_BTNS	0x01
+
 #define PSMOUSE_CMD_SETSCALE11	0x00e6
 #define PSMOUSE_CMD_SETSCALE21	0x00e7
 #define PSMOUSE_CMD_SETRES	0x10e8
@@ -53,6 +56,8 @@ struct psmouse {
 	unsigned char pktcnt;
 	unsigned char pktsize;
 	unsigned char type;
+	unsigned char oob_data_type;
+	unsigned char extra_buttons;
 	bool ignore_parity;
 	bool acks_disable_command;
 	unsigned int model;

include/uapi/linux/serio.h

@@ -17,9 +17,10 @@
 /*
  * bit masks for use in "interrupt" flags (3rd argument)
  */
-#define SERIO_TIMEOUT	1
-#define SERIO_PARITY	2
-#define SERIO_FRAME	4
+#define SERIO_TIMEOUT	BIT(0)
+#define SERIO_PARITY	BIT(1)
+#define SERIO_FRAME	BIT(2)
+#define SERIO_OOB_DATA	BIT(3)
 
 /*
  * Serio types