/*
   * drivers/input/serio/gscps2.c
   *
   * Copyright (c) 2004-2006 Helge Deller <deller@gmx.de>
   * Copyright (c) 2002 Laurent Canet <canetl@esiee.fr>
   * Copyright (c) 2002 Thibaut Varene <varenet@parisc-linux.org>
   *
   * Pieces of code based on linux-2.4's hp_mouse.c & hp_keyb.c
   *	Copyright (c) 1999 Alex deVries <alex@onefishtwo.ca>
   *	Copyright (c) 1999-2000 Philipp Rumpf <prumpf@tux.org>
   *	Copyright (c) 2000 Xavier Debacker <debackex@esiee.fr>
   *	Copyright (c) 2000-2001 Thomas Marteau <marteaut@esiee.fr>
   *
   * HP GSC PS/2 port driver, found in PA/RISC Workstations
   *
   * This file is subject to the terms and conditions of the GNU General Public
   * License.  See the file "COPYING" in the main directory of this archive
   * for more details.
   *
   * TODO:
   * - Dino testing (did HP ever shipped a machine on which this port
   *                 was usable/enabled ?)
   */
  
  #include <linux/init.h>
  #include <linux/module.h>
  #include <linux/slab.h>
  #include <linux/serio.h>
  #include <linux/input.h>
  #include <linux/interrupt.h>
  #include <linux/spinlock.h>
  #include <linux/delay.h>
  #include <linux/ioport.h>
  #include <linux/pci_ids.h>
  
  #include <asm/irq.h>
  #include <asm/io.h>
  #include <asm/parisc-device.h>
  
  MODULE_AUTHOR("Laurent Canet <canetl@esiee.fr>, Thibaut Varene <varenet@parisc-linux.org>, Helge Deller <deller@gmx.de>");
  MODULE_DESCRIPTION("HP GSC PS2 port driver");
  MODULE_LICENSE("GPL");
  MODULE_DEVICE_TABLE(parisc, gscps2_device_tbl);
  
  #define PFX "gscps2.c: "
  
  /*
   * Driver constants
   */
  
  /* various constants */
  #define ENABLE			1
  #define DISABLE			0
  
  #define GSC_DINO_OFFSET		0x0800	/* offset for DINO controller versus LASI one */
  
  /* PS/2 IO port offsets */
  #define GSC_ID			0x00	/* device ID offset (see: GSC_ID_XXX) */
  #define GSC_RESET		0x00	/* reset port offset */
  #define GSC_RCVDATA		0x04	/* receive port offset */
  #define GSC_XMTDATA		0x04	/* transmit port offset */
  #define GSC_CONTROL		0x08	/* see: Control register bits */
  #define GSC_STATUS		0x0C	/* see: Status register bits */
  
  /* Control register bits */
  #define GSC_CTRL_ENBL		0x01	/* enable interface */
  #define GSC_CTRL_LPBXR		0x02	/* loopback operation */
  #define GSC_CTRL_DIAG		0x20	/* directly control clock/data line */
  #define GSC_CTRL_DATDIR		0x40	/* data line direct control */
  #define GSC_CTRL_CLKDIR		0x80	/* clock line direct control */
  
  /* Status register bits */
  #define GSC_STAT_RBNE		0x01	/* Receive Buffer Not Empty */
  #define GSC_STAT_TBNE		0x02	/* Transmit Buffer Not Empty */
  #define GSC_STAT_TERR		0x04	/* Timeout Error */
  #define GSC_STAT_PERR		0x08	/* Parity Error */
  #define GSC_STAT_CMPINTR	0x10	/* Composite Interrupt = irq on any port */
  #define GSC_STAT_DATSHD		0x40	/* Data Line Shadow */
  #define GSC_STAT_CLKSHD		0x80	/* Clock Line Shadow */
  
  /* IDs returned by GSC_ID port register */
  #define GSC_ID_KEYBOARD		0	/* device ID values */
  #define GSC_ID_MOUSE		1
  
  
  static irqreturn_t gscps2_interrupt(int irq, void *dev);
  
  #define BUFFER_SIZE 0x0f
  
  /* GSC PS/2 port device struct */
  struct gscps2port {
  	struct list_head node;
  	struct parisc_device *padev;
  	struct serio *port;
  	spinlock_t lock;
  	char *addr;
  	u8 act, append; /* position in buffer[] */
  	struct {
  		u8 data;
  		u8 str;
  	} buffer[BUFFER_SIZE+1];
  	int id;
  };
  
  /*
   * Various HW level routines
   */
  
  #define gscps2_readb_input(x)		readb((x)+GSC_RCVDATA)
  #define gscps2_readb_control(x)		readb((x)+GSC_CONTROL)
  #define gscps2_readb_status(x)		readb((x)+GSC_STATUS)
  #define gscps2_writeb_control(x, y)	writeb((x), (y)+GSC_CONTROL)
  
  
  /*
   * wait_TBE() - wait for Transmit Buffer Empty
   */
  
  static int wait_TBE(char *addr)
  {
  	int timeout = 25000; /* device is expected to react within 250 msec */
  	while (gscps2_readb_status(addr) & GSC_STAT_TBNE) {
  		if (!--timeout)
  			return 0;	/* This should not happen */
  		udelay(10);
  	}
  	return 1;
  }
  
  
  /*
   * gscps2_flush() - flush the receive buffer
   */
  
  static void gscps2_flush(struct gscps2port *ps2port)
  {
  	while (gscps2_readb_status(ps2port->addr) & GSC_STAT_RBNE)
  		gscps2_readb_input(ps2port->addr);
  	ps2port->act = ps2port->append = 0;
  }
  
  /*
   * gscps2_writeb_output() - write a byte to the port
   *
   * returns 1 on success, 0 on error
   */
  
  static inline int gscps2_writeb_output(struct gscps2port *ps2port, u8 data)
  {
  	unsigned long flags;
  	char *addr = ps2port->addr;
  
  	if (!wait_TBE(addr)) {
  		printk(KERN_DEBUG PFX "timeout - could not write byte %#x
  ", data);
  		return 0;
  	}
  
  	while (gscps2_readb_status(ps2port->addr) & GSC_STAT_RBNE)
  		/* wait */;
  
  	spin_lock_irqsave(&ps2port->lock, flags);
  	writeb(data, addr+GSC_XMTDATA);
  	spin_unlock_irqrestore(&ps2port->lock, flags);
  
  	/* this is ugly, but due to timing of the port it seems to be necessary. */
  	mdelay(6);
  
  	/* make sure any received data is returned as fast as possible */
  	/* this is important e.g. when we set the LEDs on the keyboard */
  	gscps2_interrupt(0, NULL);
  
  	return 1;
  }
  
  
  /*
   * gscps2_enable() - enables or disables the port
   */
  
  static void gscps2_enable(struct gscps2port *ps2port, int enable)
  {
  	unsigned long flags;
  	u8 data;
  
  	/* now enable/disable the port */
  	spin_lock_irqsave(&ps2port->lock, flags);
  	gscps2_flush(ps2port);
  	data = gscps2_readb_control(ps2port->addr);
  	if (enable)
  		data |= GSC_CTRL_ENBL;
  	else
  		data &= ~GSC_CTRL_ENBL;
  	gscps2_writeb_control(data, ps2port->addr);
  	spin_unlock_irqrestore(&ps2port->lock, flags);
  	wait_TBE(ps2port->addr);
  	gscps2_flush(ps2port);
  }
  
  /*
   * gscps2_reset() - resets the PS/2 port
   */
  
  static void gscps2_reset(struct gscps2port *ps2port)
  {
  	char *addr = ps2port->addr;
  	unsigned long flags;
  
  	/* reset the interface */
  	spin_lock_irqsave(&ps2port->lock, flags);
  	gscps2_flush(ps2port);
  	writeb(0xff, addr+GSC_RESET);
  	gscps2_flush(ps2port);
  	spin_unlock_irqrestore(&ps2port->lock, flags);
  }
  
  static LIST_HEAD(ps2port_list);
  
  /**
   * gscps2_interrupt() - Interruption service routine
   *
   * This function reads received PS/2 bytes and processes them on
   * all interfaces.
   * The problematic part here is, that the keyboard and mouse PS/2 port
   * share the same interrupt and it's not possible to send data if any
   * one of them holds input data. To solve this problem we try to receive
   * the data as fast as possible and handle the reporting to the upper layer
   * later.
   */
  
  static irqreturn_t gscps2_interrupt(int irq, void *dev)
  {
  	struct gscps2port *ps2port;
  
  	list_for_each_entry(ps2port, &ps2port_list, node) {
  
  	  unsigned long flags;
  	  spin_lock_irqsave(&ps2port->lock, flags);
  
  	  while ( (ps2port->buffer[ps2port->append].str =
  		   gscps2_readb_status(ps2port->addr)) & GSC_STAT_RBNE ) {
  		ps2port->buffer[ps2port->append].data =
  				gscps2_readb_input(ps2port->addr);
  		ps2port->append = ((ps2port->append+1) & BUFFER_SIZE);
  	  }
  
  	  spin_unlock_irqrestore(&ps2port->lock, flags);
  
  	} /* list_for_each_entry */
  
  	/* all data was read from the ports - now report the data to upper layer */
  
  	list_for_each_entry(ps2port, &ps2port_list, node) {
  
  	  while (ps2port->act != ps2port->append) {
  
  	    unsigned int rxflags;
  	    u8 data, status;
  
  	    /* Did new data arrived while we read existing data ?
  	       If yes, exit now and let the new irq handler start over again */
  	    if (gscps2_readb_status(ps2port->addr) & GSC_STAT_CMPINTR)
  		return IRQ_HANDLED;
  
  	    status = ps2port->buffer[ps2port->act].str;
  	    data   = ps2port->buffer[ps2port->act].data;
  
  	    ps2port->act = ((ps2port->act+1) & BUFFER_SIZE);
  	    rxflags =	((status & GSC_STAT_TERR) ? SERIO_TIMEOUT : 0 ) |
  			((status & GSC_STAT_PERR) ? SERIO_PARITY  : 0 );
  
  	    serio_interrupt(ps2port->port, data, rxflags);
  
  	  } /* while() */
  
  	} /* list_for_each_entry */
  
  	return IRQ_HANDLED;
  }
  
  
  /*
   * gscps2_write() - send a byte out through the aux interface.
   */
  
  static int gscps2_write(struct serio *port, unsigned char data)
  {
  	struct gscps2port *ps2port = port->port_data;
  
  	if (!gscps2_writeb_output(ps2port, data)) {
  		printk(KERN_DEBUG PFX "sending byte %#x failed.
  ", data);
  		return -1;
  	}
  	return 0;
  }
  
  /*
   * gscps2_open() is called when a port is opened by the higher layer.
   * It resets and enables the port.
   */
  
  static int gscps2_open(struct serio *port)
  {
  	struct gscps2port *ps2port = port->port_data;
  
  	gscps2_reset(ps2port);
  
  	/* enable it */
  	gscps2_enable(ps2port, ENABLE);
  
  	gscps2_interrupt(0, NULL);
  
  	return 0;
  }
  
  /*
   * gscps2_close() disables the port
   */
  
  static void gscps2_close(struct serio *port)
  {
  	struct gscps2port *ps2port = port->port_data;
  	gscps2_enable(ps2port, DISABLE);
  }
  
  /**
   * gscps2_probe() - Probes PS2 devices
   * @return: success/error report
   */
  
  static int gscps2_probe(struct parisc_device *dev)
  {
  	struct gscps2port *ps2port;
  	struct serio *serio;
  	unsigned long hpa = dev->hpa.start;
  	int ret;
  
  	if (!dev->irq)
  		return -ENODEV;
  
  	/* Offset for DINO PS/2. Works with LASI even */
  	if (dev->id.sversion == 0x96)
  		hpa += GSC_DINO_OFFSET;
  
  	ps2port = kzalloc(sizeof(struct gscps2port), GFP_KERNEL);
  	serio = kzalloc(sizeof(struct serio), GFP_KERNEL);
  	if (!ps2port || !serio) {
  		ret = -ENOMEM;
  		goto fail_nomem;
  	}
  
  	dev_set_drvdata(&dev->dev, ps2port);
  
  	ps2port->port = serio;
  	ps2port->padev = dev;
  	ps2port->addr = ioremap_nocache(hpa, GSC_STATUS + 4);
  	spin_lock_init(&ps2port->lock);
  
  	gscps2_reset(ps2port);
  	ps2port->id = readb(ps2port->addr + GSC_ID) & 0x0f;
  
  	snprintf(serio->name, sizeof(serio->name), "gsc-ps2-%s",
  		 (ps2port->id == GSC_ID_KEYBOARD) ? "keyboard" : "mouse");
  	strlcpy(serio->phys, dev_name(&dev->dev), sizeof(serio->phys));
  	serio->id.type		= SERIO_8042;
  	serio->write		= gscps2_write;
  	serio->open		= gscps2_open;
  	serio->close		= gscps2_close;
  	serio->port_data	= ps2port;
  	serio->dev.parent	= &dev->dev;
  
  	ret = -EBUSY;
  	if (request_irq(dev->irq, gscps2_interrupt, IRQF_SHARED, ps2port->port->name, ps2port))
  		goto fail_miserably;
  
  	if (ps2port->id != GSC_ID_KEYBOARD && ps2port->id != GSC_ID_MOUSE) {
  		printk(KERN_WARNING PFX "Unsupported PS/2 port at 0x%08lx (id=%d) ignored
  ",
  				hpa, ps2port->id);
  		ret = -ENODEV;
  		goto fail;
  	}
  
  #if 0
  	if (!request_mem_region(hpa, GSC_STATUS + 4, ps2port->port.name))
  		goto fail;
  #endif
  
  	printk(KERN_INFO "serio: %s port at 0x%p irq %d @ %s
  ",
  		ps2port->port->name,
  		ps2port->addr,
  		ps2port->padev->irq,
  		ps2port->port->phys);
  
  	serio_register_port(ps2port->port);
  
  	list_add_tail(&ps2port->node, &ps2port_list);
  
  	return 0;
  
  fail:
  	free_irq(dev->irq, ps2port);
  
  fail_miserably:
  	iounmap(ps2port->addr);
  	release_mem_region(dev->hpa.start, GSC_STATUS + 4);
  
  fail_nomem:
  	kfree(ps2port);
  	kfree(serio);
  	return ret;
  }
  
  /**
   * gscps2_remove() - Removes PS2 devices
   * @return: success/error report
   */
  
  static int gscps2_remove(struct parisc_device *dev)
  {
  	struct gscps2port *ps2port = dev_get_drvdata(&dev->dev);
  
  	serio_unregister_port(ps2port->port);
  	free_irq(dev->irq, ps2port);
  	gscps2_flush(ps2port);
  	list_del(&ps2port->node);
  	iounmap(ps2port->addr);
  #if 0
  	release_mem_region(dev->hpa, GSC_STATUS + 4);
  #endif
  	dev_set_drvdata(&dev->dev, NULL);
  	kfree(ps2port);
  	return 0;
  }
  
  
  static struct parisc_device_id gscps2_device_tbl[] = {
  	{ HPHW_FIO, HVERSION_REV_ANY_ID, HVERSION_ANY_ID, 0x00084 }, /* LASI PS/2 */
  #ifdef DINO_TESTED
  	{ HPHW_FIO, HVERSION_REV_ANY_ID, HVERSION_ANY_ID, 0x00096 }, /* DINO PS/2 */
  #endif
  	{ 0, }	/* 0 terminated list */
  };
  
  static struct parisc_driver parisc_ps2_driver = {
  	.name		= "gsc_ps2",
  	.id_table	= gscps2_device_tbl,
  	.probe		= gscps2_probe,
  	.remove		= gscps2_remove,
  };
  
  static int __init gscps2_init(void)
  {
  	register_parisc_driver(&parisc_ps2_driver);
  	return 0;
  }
  
  static void __exit gscps2_exit(void)
  {
  	unregister_parisc_driver(&parisc_ps2_driver);
  }
  
  
  module_init(gscps2_init);
  module_exit(gscps2_exit);