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

3 files changed, 328 insertions, 0 deletions

diff --git a/drivers/input/serio/Kconfig b/drivers/input/serio/Kconfig
index 3bfe8fafc6ad..6256233d2bfb 100644
--- a/drivers/input/serio/Kconfig
+++ b/drivers/input/serio/Kconfig
@@ -226,4 +226,13 @@ config SERIO_AMS_DELTA
           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
diff --git a/drivers/input/serio/Makefile b/drivers/input/serio/Makefile
index 84c80bf7185e..dbbe37616c92 100644
--- a/drivers/input/serio/Makefile
+++ b/drivers/input/serio/Makefile
@@ -18,6 +18,7 @@ obj-$(CONFIG_SERIO_GSCPS2)	+= gscps2.o
 obj-$(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
diff --git a/drivers/input/serio/ps2mult.c b/drivers/input/serio/ps2mult.c
new file mode 100644
index 000000000000..6bce22e4e495
--- /dev/null
+++ b/drivers/input/serio/ps2mult.c
@@ -0,0 +1,318 @@
+/*
+ * 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 <dbaryshkov@gmail.com>");
+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);