Input: serio - add support for PS2Mult multiplexer protocol

PS2Mult is a simple serial protocol used for multiplexing several PS/2
streams into one serial data stream. It's used e.g. on TQM85xx series
of boards.

Signed-off-by: Dmitry Eremin-Solenikov <[e-mail]>
Signed-off-by: Dmitry Torokhov <[e-mail]>

drivers/input/serio/Kconfig

···
 	  To compile this driver as a module, choose M here;
 	  the module will be called ams_delta_serio.
 
+config SERIO_PS2MULT
+	tristate "TQC PS/2 multiplexer"
+	help
+	  Say Y here if you have the PS/2 line multiplexer like the one
+	  present on TQC boads.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called ps2mult.
+
 endif

drivers/input/serio/Makefile

···
 obj-$(CONFIG_HP_SDC)		+= hp_sdc.o
 obj-$(CONFIG_HIL_MLC)		+= hp_sdc_mlc.o hil_mlc.o
 obj-$(CONFIG_SERIO_PCIPS2)	+= pcips2.o
+obj-$(CONFIG_SERIO_PS2MULT)	+= ps2mult.o
 obj-$(CONFIG_SERIO_MACEPS2)	+= maceps2.o
 obj-$(CONFIG_SERIO_LIBPS2)	+= libps2.o
 obj-$(CONFIG_SERIO_RAW)		+= serio_raw.o

drivers/input/serio/ps2mult.c

···
+/*
+ * TQC PS/2 Multiplexer driver
+ *
+ * Copyright (C) 2010 Dmitry Eremin-Solenikov
+ *
+ * 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/kernel.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/serio.h>
+
+MODULE_AUTHOR("Dmitry Eremin-Solenikov <[e-mail]>");
+MODULE_DESCRIPTION("TQC PS/2 Multiplexer driver");
+MODULE_LICENSE("GPL");
+
+#define PS2MULT_KB_SELECTOR		0xA0
+#define PS2MULT_MS_SELECTOR		0xA1
+#define PS2MULT_ESCAPE			0x7D
+#define PS2MULT_BSYNC			0x7E
+#define PS2MULT_SESSION_START		0x55
+#define PS2MULT_SESSION_END		0x56
+
+struct ps2mult_port {
+	struct serio *serio;
+	unsigned char sel;
+	bool registered;
+};
+
+#define PS2MULT_NUM_PORTS	2
+#define PS2MULT_KBD_PORT	0
+#define PS2MULT_MOUSE_PORT	1
+
+struct ps2mult {
+	struct serio *mx_serio;
+	struct ps2mult_port ports[PS2MULT_NUM_PORTS];
+
+	spinlock_t lock;
+	struct ps2mult_port *in_port;
+	struct ps2mult_port *out_port;
+	bool escape;
+};
+
+/* First MUST come PS2MULT_NUM_PORTS selectors */
+static const unsigned char ps2mult_controls[] = {
+	PS2MULT_KB_SELECTOR, PS2MULT_MS_SELECTOR,
+	PS2MULT_ESCAPE, PS2MULT_BSYNC,
+	PS2MULT_SESSION_START, PS2MULT_SESSION_END,
+};
+
+static const struct serio_device_id ps2mult_serio_ids[] = {
+	{
+		.type	= SERIO_RS232,
+		.proto	= SERIO_PS2MULT,
+		.id	= SERIO_ANY,
+		.extra	= SERIO_ANY,
+	},
+	{ 0 }
+};
+
+MODULE_DEVICE_TABLE(serio, ps2mult_serio_ids);
+
+static void ps2mult_select_port(struct ps2mult *psm, struct ps2mult_port *port)
+{
+	struct serio *mx_serio = psm->mx_serio;
+
+	serio_write(mx_serio, port->sel);
+	psm->out_port = port;
+	dev_dbg(&mx_serio->dev, "switched to sel %02x\n", port->sel);
+}
+
+static int ps2mult_serio_write(struct serio *serio, unsigned char data)
+{
+	struct serio *mx_port = serio->parent;
+	struct ps2mult *psm = serio_get_drvdata(mx_port);
+	struct ps2mult_port *port = serio->port_data;
+	bool need_escape;
+	unsigned long flags;
+
+	spin_lock_irqsave(&psm->lock, flags);
+
+	if (psm->out_port != port)
+		ps2mult_select_port(psm, port);
+
+	need_escape = memchr(ps2mult_controls, data, sizeof(ps2mult_controls));
+
+	dev_dbg(&serio->dev,
+		"write: %s%02x\n", need_escape ? "ESC " : "", data);
+
+	if (need_escape)
+		serio_write(mx_port, PS2MULT_ESCAPE);
+
+	serio_write(mx_port, data);
+
+	spin_unlock_irqrestore(&psm->lock, flags);
+
+	return 0;
+}
+
+static int ps2mult_serio_start(struct serio *serio)
+{
+	struct ps2mult *psm = serio_get_drvdata(serio->parent);
+	struct ps2mult_port *port = serio->port_data;
+	unsigned long flags;
+
+	spin_lock_irqsave(&psm->lock, flags);
+	port->registered = true;
+	spin_unlock_irqrestore(&psm->lock, flags);
+
+	return 0;
+}
+
+static void ps2mult_serio_stop(struct serio *serio)
+{
+	struct ps2mult *psm = serio_get_drvdata(serio->parent);
+	struct ps2mult_port *port = serio->port_data;
+	unsigned long flags;
+
+	spin_lock_irqsave(&psm->lock, flags);
+	port->registered = false;
+	spin_unlock_irqrestore(&psm->lock, flags);
+}
+
+static int ps2mult_create_port(struct ps2mult *psm, int i)
+{
+	struct serio *mx_serio = psm->mx_serio;
+	struct serio *serio;
+
+	serio = kzalloc(sizeof(struct serio), GFP_KERNEL);
+	if (!serio)
+		return -ENOMEM;
+
+	strlcpy(serio->name, "TQC PS/2 Multiplexer", sizeof(serio->name));
+	snprintf(serio->phys, sizeof(serio->phys),
+		 "%s/port%d", mx_serio->phys, i);
+	serio->id.type = SERIO_8042;
+	serio->write = ps2mult_serio_write;
+	serio->start = ps2mult_serio_start;
+	serio->stop = ps2mult_serio_stop;
+	serio->parent = psm->mx_serio;
+	serio->port_data = &psm->ports[i];
+
+	psm->ports[i].serio = serio;
+
+	return 0;
+}
+
+static void ps2mult_reset(struct ps2mult *psm)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&psm->lock, flags);
+
+	serio_write(psm->mx_serio, PS2MULT_SESSION_END);
+	serio_write(psm->mx_serio, PS2MULT_SESSION_START);
+
+	ps2mult_select_port(psm, &psm->ports[PS2MULT_KBD_PORT]);
+
+	spin_unlock_irqrestore(&psm->lock, flags);
+}
+
+static int ps2mult_connect(struct serio *serio, struct serio_driver *drv)
+{
+	struct ps2mult *psm;
+	int i;
+	int error;
+
+	if (!serio->write)
+		return -EINVAL;
+
+	psm = kzalloc(sizeof(*psm), GFP_KERNEL);
+	if (!psm)
+		return -ENOMEM;
+
+	spin_lock_init(&psm->lock);
+	psm->mx_serio = serio;
+
+	for (i = 0; i < PS2MULT_NUM_PORTS; i++) {
+		psm->ports[i].sel = ps2mult_controls[i];
+		error = ps2mult_create_port(psm, i);
+		if (error)
+			goto err_out;
+	}
+
+	psm->in_port = psm->out_port = &psm->ports[PS2MULT_KBD_PORT];
+
+	serio_set_drvdata(serio, psm);
+	error = serio_open(serio, drv);
+	if (error)
+		goto err_out;
+
+	ps2mult_reset(psm);
+
+	for (i = 0; i <  PS2MULT_NUM_PORTS; i++) {
+		struct serio *s = psm->ports[i].serio;
+
+		dev_info(&serio->dev, "%s port at %s\n", s->name, serio->phys);
+		serio_register_port(s);
+	}
+
+	return 0;
+
+err_out:
+	while (--i >= 0)
+		kfree(psm->ports[i].serio);
+	kfree(serio);
+	return error;
+}
+
+static void ps2mult_disconnect(struct serio *serio)
+{
+	struct ps2mult *psm = serio_get_drvdata(serio);
+
+	/* Note that serio core already take care of children ports */
+	serio_write(serio, PS2MULT_SESSION_END);
+	serio_close(serio);
+	kfree(psm);
+
+	serio_set_drvdata(serio, NULL);
+}
+
+static int ps2mult_reconnect(struct serio *serio)
+{
+	struct ps2mult *psm = serio_get_drvdata(serio);
+
+	ps2mult_reset(psm);
+
+	return 0;
+}
+
+static irqreturn_t ps2mult_interrupt(struct serio *serio,
+				     unsigned char data, unsigned int dfl)
+{
+	struct ps2mult *psm = serio_get_drvdata(serio);
+	struct ps2mult_port *in_port;
+	unsigned long flags;
+
+	dev_dbg(&serio->dev, "Received %02x flags %02x\n", data, dfl);
+
+	spin_lock_irqsave(&psm->lock, flags);
+
+	if (psm->escape) {
+		psm->escape = false;
+		in_port = psm->in_port;
+		if (in_port->registered)
+			serio_interrupt(in_port->serio, data, dfl);
+		goto out;
+	}
+
+	switch (data) {
+	case PS2MULT_ESCAPE:
+		dev_dbg(&serio->dev, "ESCAPE\n");
+		psm->escape = true;
+		break;
+
+	case PS2MULT_BSYNC:
+		dev_dbg(&serio->dev, "BSYNC\n");
+		psm->in_port = psm->out_port;
+		break;
+
+	case PS2MULT_SESSION_START:
+		dev_dbg(&serio->dev, "SS\n");
+		break;
+
+	case PS2MULT_SESSION_END:
+		dev_dbg(&serio->dev, "SE\n");
+		break;
+
+	case PS2MULT_KB_SELECTOR:
+		dev_dbg(&serio->dev, "KB\n");
+		psm->in_port = &psm->ports[PS2MULT_KBD_PORT];
+		break;
+
+	case PS2MULT_MS_SELECTOR:
+		dev_dbg(&serio->dev, "MS\n");
+		psm->in_port = &psm->ports[PS2MULT_MOUSE_PORT];
+		break;
+
+	default:
+		in_port = psm->in_port;
+		if (in_port->registered)
+			serio_interrupt(in_port->serio, data, dfl);
+		break;
+	}
+
+ out:
+	spin_unlock_irqrestore(&psm->lock, flags);
+	return IRQ_HANDLED;
+}
+
+static struct serio_driver ps2mult_drv = {
+	.driver		= {
+		.name	= "ps2mult",
+	},
+	.description	= "TQC PS/2 Multiplexer driver",
+	.id_table	= ps2mult_serio_ids,
+	.interrupt	= ps2mult_interrupt,
+	.connect	= ps2mult_connect,
+	.disconnect	= ps2mult_disconnect,
+	.reconnect	= ps2mult_reconnect,
+};
+
+static int __init ps2mult_init(void)
+{
+	return serio_register_driver(&ps2mult_drv);
+}
+
+static void __exit ps2mult_exit(void)
+{
+	serio_unregister_driver(&ps2mult_drv);
+}
+
+module_init(ps2mult_init);
+module_exit(ps2mult_exit);

include/linux/serio.h

···
 #define SERIO_W8001	0x39
 #define SERIO_DYNAPRO	0x3a
 #define SERIO_HAMPSHIRE	0x3b
+#define SERIO_PS2MULT	0x3c
 
 #endif