daisy.c

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/*
 * IEEE 1284.3 Parallel port daisy chain and multiplexor code
 * 
 * Copyright (C) 1999, 2000  Tim Waugh <[email protected]>
 *
 * 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.h>

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

#undef DEBUG

#ifdef DEBUG
#define DPRINTK(stuff...) printk(stuff)
#else
#define DPRINTK(stuff...)
#endif

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

static int numdevs = 0;

/* 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;
}

/* 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;

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;
        printk(KERN_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;
            }

            printk(KERN_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;
}

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

    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_device(port, name, NULL, NULL, NULL, 0, NULL);
    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;
}

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)) {
        DPRINTK(KERN_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)) {
        DPRINTK(KERN_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)) {
        DPRINTK(KERN_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)) {
        DPRINTK(KERN_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)) {
        DPRINTK(KERN_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;
    DPRINTK(KERN_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;
}