/*
   * 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
  ", irq);
  		return -EAGAIN;
  	}
  	out_8(&adb->intr_enb.r, DFB | TAG);
  
  	printk("adb: mac-io driver 1.0 for unified ADB
  ");
  
  	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);
  }