/*
 * 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 <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");

#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 __iomem *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 __iomem *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)
{
        char __iomem *addr = ps2port->addr;

        if (!wait_TBE(addr)) {
                printk(KERN_DEBUG PFX "timeout - could not write byte %#x\n", data);
                return 0;
        }

        while (gscps2_readb_status(addr) & GSC_STAT_RBNE)
                /* wait */;

        scoped_guard(spinlock_irqsave, &ps2port->lock)
                writeb(data, addr+GSC_XMTDATA);

        /* 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)
{
        u8 data;

        /* now enable/disable the port */
        scoped_guard(spinlock_irqsave, &ps2port->lock) {
                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);
        }

        wait_TBE(ps2port->addr);
        gscps2_flush(ps2port);
}

/*
 * gscps2_reset() - resets the PS/2 port
 */

static void gscps2_reset(struct gscps2port *ps2port)
{
        /* reset the interface */
        guard(spinlock_irqsave)(&ps2port->lock);
        gscps2_flush(ps2port);
        writeb(0xff, ps2port->addr + GSC_RESET);
        gscps2_flush(ps2port);
}

static LIST_HEAD(ps2port_list);

static void gscps2_read_data(struct gscps2port *ps2port)
{
        u8 status;

        do {
                status = gscps2_readb_status(ps2port->addr);
                if (!(status & GSC_STAT_RBNE))
                        break;

                ps2port->buffer[ps2port->append].str = status;
                ps2port->buffer[ps2port->append].data =
                                gscps2_readb_input(ps2port->addr);
        } while (true);
}

static bool gscps2_report_data(struct gscps2port *ps2port)
{
        unsigned int rxflags;
        u8 data, status;

        while (ps2port->act != ps2port->append) {
                /*
                 * 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 true;

                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);
        }

        return false;
}

/**
 * gscps2_interrupt() - Interruption service routine
 * @irq: interrupt number which triggered (unused)
 * @dev: device pointer (unused)
 *
 * 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) {
                guard(spinlock_irqsave)(&ps2port->lock);

                gscps2_read_data(ps2port);
        } /* 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) {
                if (gscps2_report_data(ps2port)) {
                        /* More data ready - break early to restart interrupt */
                        break;
                }
        }

        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.\n", 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
 * @dev: pointer to parisc_device struct which will be probed
 *
 * @return: success/error report
 */

static int __init 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_obj(*ps2port);
        serio = kzalloc_obj(*serio);
        if (!ps2port || !serio) {
                ret = -ENOMEM;
                goto fail_nomem;
        }

        dev_set_drvdata(&dev->dev, ps2port);

        ps2port->port = serio;
        ps2port->padev = dev;
        ps2port->addr = ioremap(hpa, GSC_STATUS + 4);
        if (!ps2port->addr) {
                ret = -ENOMEM;
                goto fail_nomem;
        }
        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");
        strscpy(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\n",
                                hpa, ps2port->id);
                ret = -ENODEV;
                goto fail;
        }

#if 0
        if (!request_mem_region(hpa, GSC_STATUS + 4, ps2port->port.name))
                goto fail;
#endif

        pr_info("serio: %s port at 0x%08lx irq %d @ %s\n",
                ps2port->port->name,
                hpa,
                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
 * @dev: pointer to parisc_device which shall be removed
 *
 * @return: success/error report
 */

static void __exit 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);
}


static const struct parisc_device_id gscps2_device_tbl[] __initconst = {
        { 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 */
};
MODULE_DEVICE_TABLE(parisc, gscps2_device_tbl);

static struct parisc_driver parisc_ps2_driver __refdata = {
        .name           = "gsc_ps2",
        .id_table       = gscps2_device_tbl,
        .probe          = gscps2_probe,
        .remove         = __exit_p(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);