macio-adb.c

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/*
 * Driver for the ADB controller in the Mac I/O (Hydra) chip.
 */
#include <stdarg.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/spinlock.h>
#include <linux/interrupt.h>
#include <asm/prom.h>
#include <linux/adb.h>
#include <asm/io.h>
#include <asm/pgtable.h>
#include <asm/hydra.h>
#include <asm/irq.h>
#include <linux/init.h>
#include <linux/ioport.h>

struct preg {
    unsigned char r;
    char pad[15];
};

struct adb_regs {
    struct preg intr;
    struct preg data[9];
    struct preg intr_enb;
    struct preg dcount;
    struct preg error;
    struct preg ctrl;
    struct preg autopoll;
    struct preg active_hi;
    struct preg active_lo;
    struct preg test;
};

/* Bits in intr and intr_enb registers */
#define DFB 1       /* data from bus */
#define TAG 2       /* transfer access grant */

/* Bits in dcount register */
#define HMB 0x0f        /* how many bytes */
#define APD 0x10        /* auto-poll data */

/* Bits in error register */
#define NRE 1       /* no response error */
#define DLE 2       /* data lost error */

/* Bits in ctrl register */
#define TAR 1       /* transfer access request */
#define DTB 2       /* data to bus */
#define CRE 4       /* command response expected */
#define ADB_RST 8       /* ADB reset */

/* Bits in autopoll register */
#define APE 1       /* autopoll enable */

static volatile struct adb_regs __iomem *adb;
static struct adb_request *current_req, *last_req;
static DEFINE_SPINLOCK(macio_lock);

static int macio_probe(void);
static int macio_init(void);
static irqreturn_t macio_adb_interrupt(int irq, void *arg);
static int macio_send_request(struct adb_request *req, int sync);
static int macio_adb_autopoll(int devs);
static void macio_adb_poll(void);
static int macio_adb_reset_bus(void);

struct adb_driver macio_adb_driver = {
    "MACIO",
    macio_probe,
    macio_init,
    macio_send_request,
    /*macio_write,*/
    macio_adb_autopoll,
    macio_adb_poll,
    macio_adb_reset_bus
};

int macio_probe(void)
{
    struct device_node *np;

    np = of_find_compatible_node(NULL, "adb", "chrp,adb0");
    if (np) {
        of_node_put(np);
        return 0;
    }
    return -ENODEV;
}

int macio_init(void)
{
    struct device_node *adbs;
    struct resource r;
    unsigned int irq;

    adbs = of_find_compatible_node(NULL, "adb", "chrp,adb0");
    if (adbs == 0)
        return -ENXIO;

    if (of_address_to_resource(adbs, 0, &r)) {
        of_node_put(adbs);
        return -ENXIO;
    }
    adb = ioremap(r.start, sizeof(struct adb_regs));

    out_8(&adb->ctrl.r, 0);
    out_8(&adb->intr.r, 0);
    out_8(&adb->error.r, 0);
    out_8(&adb->active_hi.r, 0xff); /* for now, set all devices active */
    out_8(&adb->active_lo.r, 0xff);
    out_8(&adb->autopoll.r, APE);

    irq = irq_of_parse_and_map(adbs, 0);
    of_node_put(adbs);
    if (request_irq(irq, macio_adb_interrupt, 0, "ADB", (void *)0)) {
        printk(KERN_ERR "ADB: can't get irq %d\n", irq);
        return -EAGAIN;
    }
    out_8(&adb->intr_enb.r, DFB | TAG);

    printk("adb: mac-io driver 1.0 for unified ADB\n");

    return 0;
}

static int macio_adb_autopoll(int devs)
{
    unsigned long flags;
    
    spin_lock_irqsave(&macio_lock, flags);
    out_8(&adb->active_hi.r, devs >> 8);
    out_8(&adb->active_lo.r, devs);
    out_8(&adb->autopoll.r, devs? APE: 0);
    spin_unlock_irqrestore(&macio_lock, flags);
    return 0;
}

static int macio_adb_reset_bus(void)
{
    unsigned long flags;
    int timeout = 1000000;

    /* Hrm... we may want to not lock interrupts for so
     * long ... oh well, who uses that chip anyway ? :)
     * That function will be seldom used during boot
     * on rare machines, so...
     */
    spin_lock_irqsave(&macio_lock, flags);
    out_8(&adb->ctrl.r, in_8(&adb->ctrl.r) | ADB_RST);
    while ((in_8(&adb->ctrl.r) & ADB_RST) != 0) {
        if (--timeout == 0) {
            out_8(&adb->ctrl.r, in_8(&adb->ctrl.r) & ~ADB_RST);
            spin_unlock_irqrestore(&macio_lock, flags);
            return -1;
        }
    }
    spin_unlock_irqrestore(&macio_lock, flags);
    return 0;
}

/* Send an ADB command */
static int macio_send_request(struct adb_request *req, int sync)
{
    unsigned long flags;
    int i;
    
    if (req->data[0] != ADB_PACKET)
        return -EINVAL;
    
    for (i = 0; i < req->nbytes - 1; ++i)
        req->data[i] = req->data[i+1];
    --req->nbytes;
    
    req->next = NULL;
    req->sent = 0;
    req->complete = 0;
    req->reply_len = 0;

    spin_lock_irqsave(&macio_lock, flags);
    if (current_req != 0) {
        last_req->next = req;
        last_req = req;
    } else {
        current_req = last_req = req;
        out_8(&adb->ctrl.r, in_8(&adb->ctrl.r) | TAR);
    }
    spin_unlock_irqrestore(&macio_lock, flags);
    
    if (sync) {
        while (!req->complete)
            macio_adb_poll();
    }

    return 0;
}

static irqreturn_t macio_adb_interrupt(int irq, void *arg)
{
    int i, n, err;
    struct adb_request *req = NULL;
    unsigned char ibuf[16];
    int ibuf_len = 0;
    int complete = 0;
    int autopoll = 0;
    int handled = 0;

    spin_lock(&macio_lock);
    if (in_8(&adb->intr.r) & TAG) {
        handled = 1;
        if ((req = current_req) != 0) {
            /* put the current request in */
            for (i = 0; i < req->nbytes; ++i)
                out_8(&adb->data[i].r, req->data[i]);
            out_8(&adb->dcount.r, req->nbytes & HMB);
            req->sent = 1;
            if (req->reply_expected) {
                out_8(&adb->ctrl.r, DTB + CRE);
            } else {
                out_8(&adb->ctrl.r, DTB);
                current_req = req->next;
                complete = 1;
                if (current_req)
                    out_8(&adb->ctrl.r, in_8(&adb->ctrl.r) | TAR);
            }
        }
        out_8(&adb->intr.r, 0);
    }

    if (in_8(&adb->intr.r) & DFB) {
        handled = 1;
        err = in_8(&adb->error.r);
        if (current_req && current_req->sent) {
            /* this is the response to a command */
            req = current_req;
            if (err == 0) {
                req->reply_len = in_8(&adb->dcount.r) & HMB;
                for (i = 0; i < req->reply_len; ++i)
                    req->reply[i] = in_8(&adb->data[i].r);
            }
            current_req = req->next;
            complete = 1;
            if (current_req)
                out_8(&adb->ctrl.r, in_8(&adb->ctrl.r) | TAR);
        } else if (err == 0) {
            /* autopoll data */
            n = in_8(&adb->dcount.r) & HMB;
            for (i = 0; i < n; ++i)
                ibuf[i] = in_8(&adb->data[i].r);
            ibuf_len = n;
            autopoll = (in_8(&adb->dcount.r) & APD) != 0;
        }
        out_8(&adb->error.r, 0);
        out_8(&adb->intr.r, 0);
    }
    spin_unlock(&macio_lock);
    if (complete && req) {
        void (*done)(struct adb_request *) = req->done;
        mb();
        req->complete = 1;
        /* Here, we assume that if the request has a done member, the
             * struct request will survive to setting req->complete to 1
         */
        if (done)
        (*done)(req);
    }
    if (ibuf_len)
        adb_input(ibuf, ibuf_len, autopoll);

    return IRQ_RETVAL(handled);
}

static void macio_adb_poll(void)
{
    unsigned long flags;

    local_irq_save(flags);
    if (in_8(&adb->intr.r) != 0)
        macio_adb_interrupt(0, NULL);
    local_irq_restore(flags);
}