/*
   * Device driver for the IIsi-style ADB on some Mac LC and II-class machines
   *
   * Based on via-cuda.c and via-macii.c, as well as the original
   * adb-bus.c, which in turn is somewhat influenced by (but uses no
   * code from) the NetBSD HWDIRECT ADB code.  Original IIsi driver work
   * was done by Robert Thompson and integrated into the old style
   * driver by Michael Schmitz.
   *
   * Original sources (c) Alan Cox, Paul Mackerras, and others.
   *
   * Rewritten for Unified ADB by David Huggins-Daines <dhd@debian.org>
   * 
   * 7/13/2000- extensive changes by Andrew McPherson <andrew@macduff.dhs.org>
   * Works about 30% of the time now.
   */
  
  #include <linux/types.h>
  #include <linux/errno.h>
  #include <linux/kernel.h>

  #include <linux/adb.h>
  #include <linux/cuda.h>
  #include <linux/delay.h>
  #include <linux/interrupt.h>
  #include <asm/macintosh.h>
  #include <asm/macints.h>

  #include <asm/mac_via.h>
  
  static volatile unsigned char *via;
  
  /* VIA registers - spaced 0x200 bytes apart - only the ones we actually use */
  #define RS		0x200		/* skip between registers */
  #define B		0		/* B-side data */
  #define A		RS		/* A-side data */
  #define DIRB		(2*RS)		/* B-side direction (1=output) */
  #define DIRA		(3*RS)		/* A-side direction (1=output) */
  #define SR		(10*RS)		/* Shift register */
  #define ACR		(11*RS)		/* Auxiliary control register */
  #define IFR		(13*RS)		/* Interrupt flag register */
  #define IER		(14*RS)		/* Interrupt enable register */
  
  /* Bits in B data register: all active low */
  #define TREQ		0x08		/* Transfer request (input) */
  #define TACK		0x10		/* Transfer acknowledge (output) */
  #define TIP		0x20		/* Transfer in progress (output) */
  #define ST_MASK		0x30		/* mask for selecting ADB state bits */
  
  /* Bits in ACR */
  #define SR_CTRL		0x1c		/* Shift register control bits */
  #define SR_EXT		0x0c		/* Shift on external clock */
  #define SR_OUT		0x10		/* Shift out if 1 */
  
  /* Bits in IFR and IER */
  #define IER_SET		0x80		/* set bits in IER */
  #define IER_CLR		0		/* clear bits in IER */
  #define SR_INT		0x04		/* Shift register full/empty */
  #define SR_DATA		0x08		/* Shift register data */
  #define SR_CLOCK	0x10		/* Shift register clock */
  
  #define ADB_DELAY 150
  
  #undef DEBUG_MACIISI_ADB

  static struct adb_request* current_req;
  static struct adb_request* last_req;

  static unsigned char maciisi_rbuf[16];

  static unsigned char *reply_ptr;

  static int data_index;
  static int reading_reply;
  static int reply_len;
  static int tmp;
  static int need_sync;
  
  static enum maciisi_state {
      idle,
      sending,
      reading,
  } maciisi_state;
  
  static int maciisi_probe(void);
  static int maciisi_init(void);
  static int maciisi_send_request(struct adb_request* req, int sync);
  static void maciisi_sync(struct adb_request *req);
  static int maciisi_write(struct adb_request* req);

  static irqreturn_t maciisi_interrupt(int irq, void* arg);
  static void maciisi_input(unsigned char *buf, int nb);

  static int maciisi_init_via(void);
  static void maciisi_poll(void);
  static int maciisi_start(void);
  
  struct adb_driver via_maciisi_driver = {
  	"Mac IIsi",
  	maciisi_probe,
  	maciisi_init,
  	maciisi_send_request,
  	NULL, /* maciisi_adb_autopoll, */
  	maciisi_poll,
  	NULL /* maciisi_reset_adb_bus */
  };
  
  static int
  maciisi_probe(void)
  {
  	if (macintosh_config->adb_type != MAC_ADB_IISI)
  		return -ENODEV;
  
  	via = via1;
  	return 0;
  }
  
  static int
  maciisi_init(void)
  {
  	int err;
  
  	if (via == NULL)
  		return -ENODEV;
  
  	if ((err = maciisi_init_via())) {
  		printk(KERN_ERR "maciisi_init: maciisi_init_via() failed, code %d
  ", err);
  		via = NULL;
  		return err;
  	}

  	if (request_irq(IRQ_MAC_ADB, maciisi_interrupt, 0, "ADB",
  			maciisi_interrupt)) {

  		printk(KERN_ERR "maciisi_init: can't get irq %d
  ", IRQ_MAC_ADB);
  		return -EAGAIN;
  	}
  
  	printk("adb: Mac IIsi driver v0.2 for Unified ADB.
  ");
  	return 0;
  }
  
  /* Flush data from the ADB controller */
  static void
  maciisi_stfu(void)
  {
  	int status = via[B] & (TIP|TREQ);
  
  	if (status & TREQ) {
  #ifdef DEBUG_MACIISI_ADB
  		printk (KERN_DEBUG "maciisi_stfu called with TREQ high!
  ");
  #endif
  		return;
  	}
  	
  	udelay(ADB_DELAY);
  	via[ACR] &= ~SR_OUT;
  	via[IER] = IER_CLR | SR_INT;
  
  	udelay(ADB_DELAY);
  
  	status = via[B] & (TIP|TREQ);
  
  	if (!(status & TREQ))
  	{
  		via[B] |= TIP;
  
  		while(1)
  		{
  			int poll_timeout = ADB_DELAY * 5;
  			/* Poll for SR interrupt */
  			while (!(via[IFR] & SR_INT) && poll_timeout-- > 0)
  				status = via[B] & (TIP|TREQ);
  
  			tmp = via[SR]; /* Clear shift register */
  #ifdef DEBUG_MACIISI_ADB
  			printk(KERN_DEBUG "maciisi_stfu: status %x timeout %d data %x
  ",
  			       status, poll_timeout, tmp);
  #endif	
  			if(via[B] & TREQ)
  				break;
  	
  			/* ACK on-off */
  			via[B] |= TACK;
  			udelay(ADB_DELAY);
  			via[B] &= ~TACK;
  		}
  
  		/* end frame */
  		via[B] &= ~TIP;
  		udelay(ADB_DELAY);
  	}
  
  	via[IER] = IER_SET | SR_INT;	
  }
  
  /* All specifically VIA-related initialization goes here */
  static int
  maciisi_init_via(void)
  {
  	int	i;
  	
  	/* Set the lines up. We want TREQ as input TACK|TIP as output */
  	via[DIRB] = (via[DIRB] | TACK | TIP) & ~TREQ;
  	/* Shift register on input */
  	via[ACR]  = (via[ACR] & ~SR_CTRL) | SR_EXT;
  #ifdef DEBUG_MACIISI_ADB
  	printk(KERN_DEBUG "maciisi_init_via: initial status %x
  ", via[B] & (TIP|TREQ));
  #endif
  	/* Wipe any pending data and int */
  	tmp = via[SR];
  	/* Enable keyboard interrupts */
  	via[IER] = IER_SET | SR_INT;
  	/* Set initial state: idle */
  	via[B] &= ~(TACK|TIP);
  	/* Clear interrupt bit */
  	via[IFR] = SR_INT;
  
  	for(i = 0; i < 60; i++) {
  		udelay(ADB_DELAY);
  		maciisi_stfu();
  		udelay(ADB_DELAY);
  		if(via[B] & TREQ)
  			break;
  	}
  	if (i == 60)
  		printk(KERN_ERR "maciisi_init_via: bus jam?
  ");
  
  	maciisi_state = idle;
  	need_sync = 0;
  
  	return 0;
  }
  
  /* Send a request, possibly waiting for a reply */
  static int
  maciisi_send_request(struct adb_request* req, int sync)
  {
  	int i;
  
  #ifdef DEBUG_MACIISI_ADB
  	static int dump_packet = 0;
  #endif
  
  	if (via == NULL) {
  		req->complete = 1;
  		return -ENXIO;
  	}
  
  #ifdef DEBUG_MACIISI_ADB
  	if (dump_packet) {
  		printk(KERN_DEBUG "maciisi_send_request:");
  		for (i = 0; i < req->nbytes; i++) {
  			printk(" %.2x", req->data[i]);
  		}
  		printk(" sync %d
  ", sync);
  	}
  #endif
  
  	req->reply_expected = 1;
  	
  	i = maciisi_write(req);
  	if (i)
  	{
  		/* Normally, if a packet requires syncing, that happens at the end of
  		 * maciisi_send_request. But if the transfer fails, it will be restarted
  		 * by maciisi_interrupt(). We use need_sync to tell maciisi_interrupt
  		 * when to sync a packet that it sends out.
  		 * 
  		 * Suggestions on a better way to do this are welcome.
  		 */
  		if(i == -EBUSY && sync)
  			need_sync = 1;
  		else
  			need_sync = 0;
  		return i;
  	}
  	if(sync)
  		maciisi_sync(req);
  	
  	return 0;
  }
  
  /* Poll the ADB chip until the request completes */
  static void maciisi_sync(struct adb_request *req)
  {
  	int count = 0; 
  
  #ifdef DEBUG_MACIISI_ADB
  	printk(KERN_DEBUG "maciisi_sync called
  ");
  #endif
  
  	/* If for some reason the ADB chip shuts up on us, we want to avoid an endless loop. */
  	while (!req->complete && count++ < 50) {
  		maciisi_poll();
  	}
  	/* This could be BAD... when the ADB controller doesn't respond
  	 * for this long, it's probably not coming back :-( */

  	if (count > 50) /* Hopefully shouldn't happen */

  		printk(KERN_ERR "maciisi_send_request: poll timed out!
  ");
  }

  int
  maciisi_request(struct adb_request *req, void (*done)(struct adb_request *),
  	    int nbytes, ...)
  {
  	va_list list;
  	int i;
  
  	req->nbytes = nbytes;
  	req->done = done;
  	req->reply_expected = 0;
  	va_start(list, nbytes);
  	for (i = 0; i < nbytes; i++)
  		req->data[i++] = va_arg(list, int);
  	va_end(list);
  
  	return maciisi_send_request(req, 1);
  }

  /* Enqueue a request, and run the queue if possible */
  static int
  maciisi_write(struct adb_request* req)
  {
  	unsigned long flags;
  	int i;
  
  	/* We will accept CUDA packets - the VIA sends them to us, so
             it figures that we should be able to send them to it */
  	if (req->nbytes < 2 || req->data[0] > CUDA_PACKET) {
  		printk(KERN_ERR "maciisi_write: packet too small or not an ADB or CUDA packet
  ");
  		req->complete = 1;
  		return -EINVAL;
  	}

  	req->next = NULL;

  	req->sent = 0;
  	req->complete = 0;
  	req->reply_len = 0;
  	
  	local_irq_save(flags);
  
  	if (current_req) {
  		last_req->next = req;
  		last_req = req;
  	} else {
  		current_req = req;
  		last_req = req;
  	}
  	if (maciisi_state == idle)
  	{
  		i = maciisi_start();
  		if(i != 0)
  		{
  			local_irq_restore(flags);
  			return i;
  		}
  	}
  	else
  	{
  #ifdef DEBUG_MACIISI_ADB
  		printk(KERN_DEBUG "maciisi_write: would start, but state is %d
  ", maciisi_state);
  #endif
  		local_irq_restore(flags);
  		return -EBUSY;
  	}
  
  	local_irq_restore(flags);
  
  	return 0;
  }
  
  static int
  maciisi_start(void)
  {
  	struct adb_request* req;
  	int status;
  
  #ifdef DEBUG_MACIISI_ADB
  	status = via[B] & (TIP | TREQ);
  
  	printk(KERN_DEBUG "maciisi_start called, state=%d, status=%x, ifr=%x
  ", maciisi_state, status, via[IFR]);
  #endif
  
  	if (maciisi_state != idle) {
  		/* shouldn't happen */
  		printk(KERN_ERR "maciisi_start: maciisi_start called when driver busy!
  ");
  		return -EBUSY;
  	}
  
  	req = current_req;
  	if (req == NULL)
  		return -EINVAL;
  
  	status = via[B] & (TIP|TREQ);
  	if (!(status & TREQ)) {
  #ifdef DEBUG_MACIISI_ADB
  		printk(KERN_DEBUG "maciisi_start: bus busy - aborting
  ");
  #endif
  		return -EBUSY;
  	}
  
  	/* Okay, send */
  #ifdef DEBUG_MACIISI_ADB
  	printk(KERN_DEBUG "maciisi_start: sending
  ");
  #endif
  	/* Set state to active */
  	via[B] |= TIP;
  	/* ACK off */
  	via[B] &= ~TACK;
  	/* Delay */
  	udelay(ADB_DELAY);
  	/* Shift out and send */
  	via[ACR] |= SR_OUT;
  	via[SR] = req->data[0];
  	data_index = 1;
  	/* ACK on */
  	via[B] |= TACK;
  	maciisi_state = sending;
  
  	return 0;
  }
  
  void
  maciisi_poll(void)
  {
  	unsigned long flags;
  
  	local_irq_save(flags);
  	if (via[IFR] & SR_INT) {

  		maciisi_interrupt(0, NULL);

  	}
  	else /* avoid calling this function too quickly in a loop */
  		udelay(ADB_DELAY);
  
  	local_irq_restore(flags);
  }
  
  /* Shift register interrupt - this is *supposed* to mean that the
     register is either full or empty. In practice, I have no idea what
     it means :( */
  static irqreturn_t

  maciisi_interrupt(int irq, void* arg)

  {
  	int status;
  	struct adb_request *req;
  #ifdef DEBUG_MACIISI_ADB
  	static int dump_reply = 0;
  #endif
  	int i;
  	unsigned long flags;
  
  	local_irq_save(flags);
  
  	status = via[B] & (TIP|TREQ);
  #ifdef DEBUG_MACIISI_ADB
  	printk(KERN_DEBUG "state %d status %x ifr %x
  ", maciisi_state, status, via[IFR]);
  #endif
  
  	if (!(via[IFR] & SR_INT)) {
  		/* Shouldn't happen, we hope */
  		printk(KERN_ERR "maciisi_interrupt: called without interrupt flag set
  ");
  		local_irq_restore(flags);
  		return IRQ_NONE;
  	}
  
  	/* Clear the interrupt */
  	/* via[IFR] = SR_INT; */
  
   switch_start:
  	switch (maciisi_state) {
  	case idle:
  		if (status & TIP)
  			printk(KERN_ERR "maciisi_interrupt: state is idle but TIP asserted!
  ");
  
  		if(!reading_reply)
  			udelay(ADB_DELAY);
  		/* Shift in */
  		via[ACR] &= ~SR_OUT;
   		/* Signal start of frame */
  		via[B] |= TIP;
  		/* Clear the interrupt (throw this value on the floor, it's useless) */
  		tmp = via[SR];
  		/* ACK adb chip, high-low */
  		via[B] |= TACK;
  		udelay(ADB_DELAY);
  		via[B] &= ~TACK;
  		reply_len = 0;
  		maciisi_state = reading;
  		if (reading_reply) {
  			reply_ptr = current_req->reply;
  		} else {
  			reply_ptr = maciisi_rbuf;
  		}
  		break;
  
  	case sending:
  		/* via[SR]; */
  		/* Set ACK off */
  		via[B] &= ~TACK;
  		req = current_req;
  
  		if (!(status & TREQ)) {
  			/* collision */
  			printk(KERN_ERR "maciisi_interrupt: send collision
  ");
  			/* Set idle and input */
  			via[ACR] &= ~SR_OUT;
  			tmp = via[SR];
  			via[B] &= ~TIP;
  			/* Must re-send */
  			reading_reply = 0;
  			reply_len = 0;
  			maciisi_state = idle;
  			udelay(ADB_DELAY);
  			/* process this now, because the IFR has been cleared */
  			goto switch_start;
  		}
  
  		udelay(ADB_DELAY);
  
  		if (data_index >= req->nbytes) {
  			/* Sent the whole packet, put the bus back in idle state */
  			/* Shift in, we are about to read a reply (hopefully) */
  			via[ACR] &= ~SR_OUT;
  			tmp = via[SR];
  			/* End of frame */
  			via[B] &= ~TIP;
  			req->sent = 1;
  			maciisi_state = idle;
  			if (req->reply_expected) {
  				/* Note: only set this once we've
                                     successfully sent the packet */
  				reading_reply = 1;
  			} else {
  				current_req = req->next;
  				if (req->done)
  					(*req->done)(req);
  				/* Do any queued requests now */
  				i = maciisi_start();
  				if(i == 0 && need_sync) {
  					/* Packet needs to be synced */
  					maciisi_sync(current_req);
  				}
  				if(i != -EBUSY)
  					need_sync = 0;
  			}
  		} else {
  			/* Sending more stuff */
  			/* Shift out */
  			via[ACR] |= SR_OUT;
  			/* Write */
  			via[SR] = req->data[data_index++];
  			/* Signal 'byte ready' */
  			via[B] |= TACK;
  		}
  		break;
  
  	case reading:
  		/* Shift in */
  		/* via[ACR] &= ~SR_OUT; */ /* Not in 2.2 */
  		if (reply_len++ > 16) {
  			printk(KERN_ERR "maciisi_interrupt: reply too long, aborting read
  ");
  			via[B] |= TACK;
  			udelay(ADB_DELAY);
  			via[B] &= ~(TACK|TIP);
  			maciisi_state = idle;
  			i = maciisi_start();
  			if(i == 0 && need_sync) {
  				/* Packet needs to be synced */
  				maciisi_sync(current_req);
  			}
  			if(i != -EBUSY)
  				need_sync = 0;
  			break;
  		}
  		/* Read data */
  		*reply_ptr++ = via[SR];
  		status = via[B] & (TIP|TREQ);
  		/* ACK on/off */
  		via[B] |= TACK;
  		udelay(ADB_DELAY);
  		via[B] &= ~TACK;	
  		if (!(status & TREQ))
  			break; /* more stuff to deal with */
  		
  		/* end of frame */
  		via[B] &= ~TIP;
  		tmp = via[SR]; /* That's what happens in 2.2 */
  		udelay(ADB_DELAY); /* Give controller time to recover */
  
  		/* end of packet, deal with it */
  		if (reading_reply) {
  			req = current_req;
  			req->reply_len = reply_ptr - req->reply;
  			if (req->data[0] == ADB_PACKET) {
  				/* Have to adjust the reply from ADB commands */
  				if (req->reply_len <= 2 || (req->reply[1] & 2) != 0) {
  					/* the 0x2 bit indicates no response */
  					req->reply_len = 0;
  				} else {
  					/* leave just the command and result bytes in the reply */
  					req->reply_len -= 2;
  					memmove(req->reply, req->reply + 2, req->reply_len);
  				}
  			}
  #ifdef DEBUG_MACIISI_ADB
  			if (dump_reply) {
  				int i;
  				printk(KERN_DEBUG "maciisi_interrupt: reply is ");
  				for (i = 0; i < req->reply_len; ++i)
  					printk(" %.2x", req->reply[i]);
  				printk("
  ");
  			}
  #endif
  			req->complete = 1;
  			current_req = req->next;
  			if (req->done)
  				(*req->done)(req);
  			/* Obviously, we got it */
  			reading_reply = 0;
  		} else {

  			maciisi_input(maciisi_rbuf, reply_ptr - maciisi_rbuf);

  		}
  		maciisi_state = idle;
  		status = via[B] & (TIP|TREQ);
  		if (!(status & TREQ)) {
  			/* Timeout?! More likely, another packet coming in already */
  #ifdef DEBUG_MACIISI_ADB
  			printk(KERN_DEBUG "extra data after packet: status %x ifr %x
  ",
  			       status, via[IFR]);
  #endif
  #if 0
  			udelay(ADB_DELAY);
  			via[B] |= TIP;
  
  			maciisi_state = reading;
  			reading_reply = 0;
  			reply_ptr = maciisi_rbuf;
  #else
  			/* Process the packet now */
  			reading_reply = 0;
  			goto switch_start;
  #endif
  			/* We used to do this... but the controller might actually have data for us */
  			/* maciisi_stfu(); */
  		}
  		else {
  			/* Do any queued requests now if possible */
  			i = maciisi_start();
  			if(i == 0 && need_sync) {
  				/* Packet needs to be synced */
  				maciisi_sync(current_req);
  			}
  			if(i != -EBUSY)
  				need_sync = 0;
  		}
  		break;
  
  	default:
  		printk("maciisi_interrupt: unknown maciisi_state %d?
  ", maciisi_state);
  	}
  	local_irq_restore(flags);
  	return IRQ_HANDLED;
  }
  
  static void

  maciisi_input(unsigned char *buf, int nb)

  {
  #ifdef DEBUG_MACIISI_ADB
      int i;
  #endif
  
      switch (buf[0]) {
      case ADB_PACKET:

  	    adb_input(buf+2, nb-2, buf[1] & 0x40);

  	    break;
      default:
  #ifdef DEBUG_MACIISI_ADB
  	    printk(KERN_DEBUG "data from IIsi ADB (%d bytes):", nb);
  	    for (i = 0; i < nb; ++i)
  		    printk(" %.2x", buf[i]);
  	    printk("
  ");
  #endif
  	    break;
      }
  }