/*
 * IEEE 1284.3 Parallel port daisy chain and multiplexor code
 * 
 * Copyright (C) 1999, 2000  Tim Waugh <tim@cyberelk.demon.co.uk>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 *
 * ??-12-1998: Initial implementation.
 * 31-01-1999: Make port-cloning transparent.
 * 13-02-1999: Move DeviceID technique from parport_probe.
 * 13-03-1999: Get DeviceID from non-IEEE 1284.3 devices too.
 * 22-02-2000: Count devices that are actually detected.
 *
 * Any part of this program may be used in documents licensed under
 * the GNU Free Documentation License, Version 1.1 or any later version
 * published by the Free Software Foundation.
 */

#include <linux/module.h>
#include <linux/parport.h>
#include <linux/delay.h>
#include <linux/slab.h>
#include <linux/sched/signal.h>

#include <asm/current.h>
#include <linux/uaccess.h>

#undef DEBUG

static struct daisydev {
        struct daisydev *next;
        struct parport *port;
        int daisy;
        int devnum;
} *topology = NULL;
static DEFINE_SPINLOCK(topology_lock);

static int numdevs;
static bool daisy_init_done;

/* Forward-declaration of lower-level functions. */
static int mux_present(struct parport *port);
static int num_mux_ports(struct parport *port);
static int select_port(struct parport *port);
static int assign_addrs(struct parport *port);

/* Add a device to the discovered topology. */
static void add_dev(int devnum, struct parport *port, int daisy)
{
        struct daisydev *newdev, **p;
        newdev = kmalloc(sizeof(struct daisydev), GFP_KERNEL);
        if (newdev) {
                newdev->port = port;
                newdev->daisy = daisy;
                newdev->devnum = devnum;
                spin_lock(&topology_lock);
                for (p = &topology; *p && (*p)->devnum<devnum; p = &(*p)->next)
                        ;
                newdev->next = *p;
                *p = newdev;
                spin_unlock(&topology_lock);
        }
}

/* Clone a parport (actually, make an alias). */
static struct parport *clone_parport(struct parport *real, int muxport)
{
        struct parport *extra = parport_register_port(real->base,
                                                       real->irq,
                                                       real->dma,
                                                       real->ops);
        if (extra) {
                extra->portnum = real->portnum;
                extra->physport = real;
                extra->muxport = muxport;
                real->slaves[muxport-1] = extra;
        }

        return extra;
}

static int daisy_drv_probe(struct pardevice *par_dev)
{
        struct device_driver *drv = par_dev->dev.driver;

        if (strcmp(drv->name, "daisy_drv"))
                return -ENODEV;
        if (strcmp(par_dev->name, daisy_dev_name))
                return -ENODEV;

        return 0;
}

static struct parport_driver daisy_driver = {
        .name = "daisy_drv",
        .probe = daisy_drv_probe,
        .devmodel = true,
};

/* Discover the IEEE1284.3 topology on a port -- muxes and daisy chains.
 * Return value is number of devices actually detected. */
int parport_daisy_init(struct parport *port)
{
        int detected = 0;
        char *deviceid;
        static const char *th[] = { /*0*/"th", "st", "nd", "rd", "th" };
        int num_ports;
        int i;
        int last_try = 0;

        if (!daisy_init_done) {
                /*
                 * flag should be marked true first as
                 * parport_register_driver() might try to load the low
                 * level driver which will lead to announcing new ports
                 * and which will again come back here at
                 * parport_daisy_init()
                 */
                daisy_init_done = true;
                i = parport_register_driver(&daisy_driver);
                if (i) {
                        pr_err("daisy registration failed\n");
                        daisy_init_done = false;
                        return i;
                }
        }

again:
        /* Because this is called before any other devices exist,
         * we don't have to claim exclusive access.  */

        /* If mux present on normal port, need to create new
         * parports for each extra port. */
        if (port->muxport < 0 && mux_present(port) &&
            /* don't be fooled: a mux must have 2 or 4 ports. */
            ((num_ports = num_mux_ports(port)) == 2 || num_ports == 4)) {
                /* Leave original as port zero. */
                port->muxport = 0;
                pr_info("%s: 1st (default) port of %d-way multiplexor\n",
                        port->name, num_ports);
                for (i = 1; i < num_ports; i++) {
                        /* Clone the port. */
                        struct parport *extra = clone_parport(port, i);
                        if (!extra) {
                                if (signal_pending(current))
                                        break;

                                schedule();
                                continue;
                        }

                        pr_info("%s: %d%s port of %d-way multiplexor on %s\n",
                                extra->name, i + 1, th[i + 1], num_ports,
                                port->name);

                        /* Analyse that port too.  We won't recurse
                           forever because of the 'port->muxport < 0'
                           test above. */
                        parport_daisy_init(extra);
                }
        }

        if (port->muxport >= 0)
                select_port(port);

        parport_daisy_deselect_all(port);
        detected += assign_addrs(port);

        /* Count the potential legacy device at the end. */
        add_dev(numdevs++, port, -1);

        /* Find out the legacy device's IEEE 1284 device ID. */
        deviceid = kmalloc(1024, GFP_KERNEL);
        if (deviceid) {
                if (parport_device_id(numdevs - 1, deviceid, 1024) > 2)
                        detected++;

                kfree(deviceid);
        }

        if (!detected && !last_try) {
                /* No devices were detected.  Perhaps they are in some
                   funny state; let's try to reset them and see if
                   they wake up. */
                parport_daisy_fini(port);
                parport_write_control(port, PARPORT_CONTROL_SELECT);
                udelay(50);
                parport_write_control(port,
                                       PARPORT_CONTROL_SELECT |
                                       PARPORT_CONTROL_INIT);
                udelay(50);
                last_try = 1;
                goto again;
        }

        return detected;
}

/* Forget about devices on a physical port. */
void parport_daisy_fini(struct parport *port)
{
        struct daisydev **p;

        spin_lock(&topology_lock);
        p = &topology;
        while (*p) {
                struct daisydev *dev = *p;
                if (dev->port != port) {
                        p = &dev->next;
                        continue;
                }
                *p = dev->next;
                kfree(dev);
        }

        /* Gaps in the numbering could be handled better.  How should
           someone enumerate through all IEEE1284.3 devices in the
           topology?. */
        if (!topology) numdevs = 0;
        spin_unlock(&topology_lock);
        return;
}

/**
 *      parport_open - find a device by canonical device number
 *      @devnum: canonical device number
 *      @name: name to associate with the device
 *
 *      This function is similar to parport_register_device(), except
 *      that it locates a device by its number rather than by the port
 *      it is attached to.
 *
 *      All parameters except for @devnum are the same as for
 *      parport_register_device().  The return value is the same as
 *      for parport_register_device().
 **/

struct pardevice *parport_open(int devnum, const char *name)
{
        struct daisydev *p = topology;
        struct pardev_cb par_cb;
        struct parport *port;
        struct pardevice *dev;
        int daisy;

        memset(&par_cb, 0, sizeof(par_cb));
        spin_lock(&topology_lock);
        while (p && p->devnum != devnum)
                p = p->next;

        if (!p) {
                spin_unlock(&topology_lock);
                return NULL;
        }

        daisy = p->daisy;
        port = parport_get_port(p->port);
        spin_unlock(&topology_lock);

        dev = parport_register_dev_model(port, name, &par_cb, devnum);
        parport_put_port(port);
        if (!dev)
                return NULL;

        dev->daisy = daisy;

        /* Check that there really is a device to select. */
        if (daisy >= 0) {
                int selected;
                parport_claim_or_block(dev);
                selected = port->daisy;
                parport_release(dev);

                if (selected != daisy) {
                        /* No corresponding device. */
                        parport_unregister_device(dev);
                        return NULL;
                }
        }

        return dev;
}

/**
 *      parport_close - close a device opened with parport_open()
 *      @dev: device to close
 *
 *      This is to parport_open() as parport_unregister_device() is to
 *      parport_register_device().
 **/

void parport_close(struct pardevice *dev)
{
        parport_unregister_device(dev);
}

/* Send a daisy-chain-style CPP command packet. */
static int cpp_daisy(struct parport *port, int cmd)
{
        unsigned char s;

        parport_data_forward(port);
        parport_write_data(port, 0xaa); udelay(2);
        parport_write_data(port, 0x55); udelay(2);
        parport_write_data(port, 0x00); udelay(2);
        parport_write_data(port, 0xff); udelay(2);
        s = parport_read_status(port) & (PARPORT_STATUS_BUSY
                                          | PARPORT_STATUS_PAPEROUT
                                          | PARPORT_STATUS_SELECT
                                          | PARPORT_STATUS_ERROR);
        if (s != (PARPORT_STATUS_BUSY
                  | PARPORT_STATUS_PAPEROUT
                  | PARPORT_STATUS_SELECT
                  | PARPORT_STATUS_ERROR)) {
                pr_debug("%s: cpp_daisy: aa5500ff(%02x)\n", port->name, s);
                return -ENXIO;
        }

        parport_write_data(port, 0x87); udelay(2);
        s = parport_read_status(port) & (PARPORT_STATUS_BUSY
                                          | PARPORT_STATUS_PAPEROUT
                                          | PARPORT_STATUS_SELECT
                                          | PARPORT_STATUS_ERROR);
        if (s != (PARPORT_STATUS_SELECT | PARPORT_STATUS_ERROR)) {
                pr_debug("%s: cpp_daisy: aa5500ff87(%02x)\n", port->name, s);
                return -ENXIO;
        }

        parport_write_data(port, 0x78); udelay(2);
        parport_write_data(port, cmd); udelay(2);
        parport_frob_control(port,
                              PARPORT_CONTROL_STROBE,
                              PARPORT_CONTROL_STROBE);
        udelay(1);
        s = parport_read_status(port);
        parport_frob_control(port, PARPORT_CONTROL_STROBE, 0);
        udelay(1);
        parport_write_data(port, 0xff); udelay(2);

        return s;
}

/* Send a mux-style CPP command packet. */
static int cpp_mux(struct parport *port, int cmd)
{
        unsigned char s;
        int rc;

        parport_data_forward(port);
        parport_write_data(port, 0xaa); udelay(2);
        parport_write_data(port, 0x55); udelay(2);
        parport_write_data(port, 0xf0); udelay(2);
        parport_write_data(port, 0x0f); udelay(2);
        parport_write_data(port, 0x52); udelay(2);
        parport_write_data(port, 0xad); udelay(2);
        parport_write_data(port, cmd); udelay(2);

        s = parport_read_status(port);
        if (!(s & PARPORT_STATUS_ACK)) {
                pr_debug("%s: cpp_mux: aa55f00f52ad%02x(%02x)\n",
                         port->name, cmd, s);
                return -EIO;
        }

        rc = (((s & PARPORT_STATUS_SELECT   ? 1 : 0) << 0) |
              ((s & PARPORT_STATUS_PAPEROUT ? 1 : 0) << 1) |
              ((s & PARPORT_STATUS_BUSY     ? 0 : 1) << 2) |
              ((s & PARPORT_STATUS_ERROR    ? 0 : 1) << 3));

        return rc;
}

void parport_daisy_deselect_all(struct parport *port)
{
        cpp_daisy(port, 0x30);
}

int parport_daisy_select(struct parport *port, int daisy, int mode)
{
        switch (mode)
        {
                // For these modes we should switch to EPP mode:
                case IEEE1284_MODE_EPP:
                case IEEE1284_MODE_EPPSL:
                case IEEE1284_MODE_EPPSWE:
                        return !(cpp_daisy(port, 0x20 + daisy) &
                                 PARPORT_STATUS_ERROR);

                // For these modes we should switch to ECP mode:
                case IEEE1284_MODE_ECP:
                case IEEE1284_MODE_ECPRLE:
                case IEEE1284_MODE_ECPSWE: 
                        return !(cpp_daisy(port, 0xd0 + daisy) &
                                 PARPORT_STATUS_ERROR);

                // Nothing was told for BECP in Daisy chain specification.
                // May be it's wise to use ECP?
                case IEEE1284_MODE_BECP:
                // Others use compat mode
                case IEEE1284_MODE_NIBBLE:
                case IEEE1284_MODE_BYTE:
                case IEEE1284_MODE_COMPAT:
                default:
                        return !(cpp_daisy(port, 0xe0 + daisy) &
                                 PARPORT_STATUS_ERROR);
        }
}

static int mux_present(struct parport *port)
{
        return cpp_mux(port, 0x51) == 3;
}

static int num_mux_ports(struct parport *port)
{
        return cpp_mux(port, 0x58);
}

static int select_port(struct parport *port)
{
        int muxport = port->muxport;
        return cpp_mux(port, 0x60 + muxport) == muxport;
}

static int assign_addrs(struct parport *port)
{
        unsigned char s;
        unsigned char daisy;
        int thisdev = numdevs;
        int detected;
        char *deviceid;

        parport_data_forward(port);
        parport_write_data(port, 0xaa); udelay(2);
        parport_write_data(port, 0x55); udelay(2);
        parport_write_data(port, 0x00); udelay(2);
        parport_write_data(port, 0xff); udelay(2);
        s = parport_read_status(port) & (PARPORT_STATUS_BUSY
                                          | PARPORT_STATUS_PAPEROUT
                                          | PARPORT_STATUS_SELECT
                                          | PARPORT_STATUS_ERROR);
        if (s != (PARPORT_STATUS_BUSY
                  | PARPORT_STATUS_PAPEROUT
                  | PARPORT_STATUS_SELECT
                  | PARPORT_STATUS_ERROR)) {
                pr_debug("%s: assign_addrs: aa5500ff(%02x)\n", port->name, s);
                return 0;
        }

        parport_write_data(port, 0x87); udelay(2);
        s = parport_read_status(port) & (PARPORT_STATUS_BUSY
                                          | PARPORT_STATUS_PAPEROUT
                                          | PARPORT_STATUS_SELECT
                                          | PARPORT_STATUS_ERROR);
        if (s != (PARPORT_STATUS_SELECT | PARPORT_STATUS_ERROR)) {
                pr_debug("%s: assign_addrs: aa5500ff87(%02x)\n", port->name, s);
                return 0;
        }

        parport_write_data(port, 0x78); udelay(2);
        s = parport_read_status(port);

        for (daisy = 0;
             (s & (PARPORT_STATUS_PAPEROUT|PARPORT_STATUS_SELECT))
                     == (PARPORT_STATUS_PAPEROUT|PARPORT_STATUS_SELECT)
                     && daisy < 4;
             ++daisy) {
                parport_write_data(port, daisy);
                udelay(2);
                parport_frob_control(port,
                                      PARPORT_CONTROL_STROBE,
                                      PARPORT_CONTROL_STROBE);
                udelay(1);
                parport_frob_control(port, PARPORT_CONTROL_STROBE, 0);
                udelay(1);

                add_dev(numdevs++, port, daisy);

                /* See if this device thought it was the last in the
                 * chain. */
                if (!(s & PARPORT_STATUS_BUSY))
                        break;

                /* We are seeing pass through status now. We see
                   last_dev from next device or if last_dev does not
                   work status lines from some non-daisy chain
                   device. */
                s = parport_read_status(port);
        }

        parport_write_data(port, 0xff); udelay(2);
        detected = numdevs - thisdev;
        pr_debug("%s: Found %d daisy-chained devices\n", port->name, detected);

        /* Ask the new devices to introduce themselves. */
        deviceid = kmalloc(1024, GFP_KERNEL);
        if (!deviceid) return 0;

        for (daisy = 0; thisdev < numdevs; thisdev++, daisy++)
                parport_device_id(thisdev, deviceid, 1024);

        kfree(deviceid);
        return detected;
}