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macio-adb.c

/*
 * 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 <asm/system.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 seldomly 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);
                  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);
}

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