/*
   * Device driver for the via-cuda on Apple Powermacs.
   *
   * The VIA (versatile interface adapter) interfaces to the CUDA,
   * a 6805 microprocessor core which controls the ADB (Apple Desktop
   * Bus) which connects to the keyboard and mouse.  The CUDA also
   * controls system power and the RTC (real time clock) chip.
   *
   * Copyright (C) 1996 Paul Mackerras.
   */
  #include <stdarg.h>

  #include <linux/types.h>
  #include <linux/errno.h>
  #include <linux/kernel.h>
  #include <linux/delay.h>

  #include <linux/adb.h>
  #include <linux/cuda.h>
  #include <linux/spinlock.h>
  #include <linux/interrupt.h>
  #ifdef CONFIG_PPC
  #include <asm/prom.h>
  #include <asm/machdep.h>
  #else
  #include <asm/macintosh.h>
  #include <asm/macints.h>

  #include <asm/mac_via.h>
  #endif
  #include <asm/io.h>
  #include <asm/system.h>
  #include <linux/init.h>
  
  static volatile unsigned char __iomem *via;
  static DEFINE_SPINLOCK(cuda_lock);

  /* VIA registers - spaced 0x200 bytes apart */
  #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 T1CL		(4*RS)		/* Timer 1 ctr/latch (low 8 bits) */
  #define T1CH		(5*RS)		/* Timer 1 counter (high 8 bits) */
  #define T1LL		(6*RS)		/* Timer 1 latch (low 8 bits) */
  #define T1LH		(7*RS)		/* Timer 1 latch (high 8 bits) */
  #define T2CL		(8*RS)		/* Timer 2 ctr/latch (low 8 bits) */
  #define T2CH		(9*RS)		/* Timer 2 counter (high 8 bits) */
  #define SR		(10*RS)		/* Shift register */
  #define ACR		(11*RS)		/* Auxiliary control register */
  #define PCR		(12*RS)		/* Peripheral control register */
  #define IFR		(13*RS)		/* Interrupt flag register */
  #define IER		(14*RS)		/* Interrupt enable register */
  #define ANH		(15*RS)		/* A-side data, no handshake */
  
  /* 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) */
  
  /* 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 */
  
  static enum cuda_state {
      idle,
      sent_first_byte,
      sending,
      reading,
      read_done,
      awaiting_reply
  } cuda_state;
  
  static struct adb_request *current_req;
  static struct adb_request *last_req;
  static unsigned char cuda_rbuf[16];
  static unsigned char *reply_ptr;
  static int reading_reply;
  static int data_index;

  static int cuda_irq;

  #ifdef CONFIG_PPC
  static struct device_node *vias;
  #endif

  static int cuda_fully_inited;

  
  #ifdef CONFIG_ADB
  static int cuda_probe(void);

  static int cuda_send_request(struct adb_request *req, int sync);
  static int cuda_adb_autopoll(int devs);
  static int cuda_reset_adb_bus(void);
  #endif /* CONFIG_ADB */
  
  static int cuda_init_via(void);
  static void cuda_start(void);

  static irqreturn_t cuda_interrupt(int irq, void *arg);
  static void cuda_input(unsigned char *buf, int nb);

  void cuda_poll(void);
  static int cuda_write(struct adb_request *req);
  
  int cuda_request(struct adb_request *req,
  		 void (*done)(struct adb_request *), int nbytes, ...);
  
  #ifdef CONFIG_ADB
  struct adb_driver via_cuda_driver = {

  	.name         = "CUDA",
  	.probe        = cuda_probe,
  	.send_request = cuda_send_request,
  	.autopoll     = cuda_adb_autopoll,
  	.poll         = cuda_poll,
  	.reset_bus    = cuda_reset_adb_bus,

  };
  #endif /* CONFIG_ADB */

  #ifdef CONFIG_MAC
  int __init find_via_cuda(void)
  {
      struct adb_request req;
      int err;
  
      if (macintosh_config->adb_type != MAC_ADB_CUDA)
  	return 0;
  
      via = via1;
      cuda_state = idle;
  
      err = cuda_init_via();
      if (err) {
  	printk(KERN_ERR "cuda_init_via() failed
  ");
  	via = NULL;
  	return 0;
      }
  
      /* enable autopoll */
      cuda_request(&req, NULL, 3, CUDA_PACKET, CUDA_AUTOPOLL, 1);
      while (!req.complete)
  	cuda_poll();
  
      return 1;
  }
  #else

  int __init find_via_cuda(void)

  {

      struct adb_request req;

      phys_addr_t taddr;

      const u32 *reg;

      int err;

  
      if (vias != 0)
  	return 1;

      vias = of_find_node_by_name(NULL, "via-cuda");

      if (vias == 0)
  	return 0;

      reg = of_get_property(vias, "reg", NULL);

      if (reg == NULL) {
  	    printk(KERN_ERR "via-cuda: No \"reg\" property !
  ");
  	    goto fail;
      }
      taddr = of_translate_address(vias, reg);
      if (taddr == 0) {
  	    printk(KERN_ERR "via-cuda: Can't translate address !
  ");
  	    goto fail;
      }
      via = ioremap(taddr, 0x2000);
      if (via == NULL) {
  	    printk(KERN_ERR "via-cuda: Can't map address !
  ");
  	    goto fail;

      }

  
      cuda_state = idle;
      sys_ctrler = SYS_CTRLER_CUDA;
  
      err = cuda_init_via();
      if (err) {
  	printk(KERN_ERR "cuda_init_via() failed
  ");
  	via = NULL;
  	return 0;
      }
  
      /* Clear and enable interrupts, but only on PPC. On 68K it's done  */
      /* for us by the main VIA driver in arch/m68k/mac/via.c        */

      out_8(&via[IFR], 0x7f);	/* clear interrupts by writing 1s */
      out_8(&via[IER], IER_SET|SR_INT); /* enable interrupt from SR */

  
      /* enable autopoll */
      cuda_request(&req, NULL, 3, CUDA_PACKET, CUDA_AUTOPOLL, 1);
      while (!req.complete)
  	cuda_poll();
  
      return 1;

  
   fail:
      of_node_put(vias);
      vias = NULL;
      return 0;

  }

  #endif /* !defined CONFIG_MAC */

  
  static int __init via_cuda_start(void)
  {
      if (via == NULL)
  	return -ENODEV;

  #ifdef CONFIG_MAC

      cuda_irq = IRQ_MAC_ADB;

  #else

      cuda_irq = irq_of_parse_and_map(vias, 0);
      if (cuda_irq == NO_IRQ) {

  	printk(KERN_ERR "via-cuda: can't map interrupts for %s
  ",
  	       vias->full_name);
  	return -ENODEV;
      }

  #endif

      if (request_irq(cuda_irq, cuda_interrupt, 0, "ADB", cuda_interrupt)) {
  	printk(KERN_ERR "via-cuda: can't request irq %d
  ", cuda_irq);

  	return -EAGAIN;
      }
  
      printk("Macintosh CUDA driver v0.5 for Unified ADB.
  ");
  
      cuda_fully_inited = 1;
      return 0;
  }
  
  device_initcall(via_cuda_start);
  
  #ifdef CONFIG_ADB
  static int
  cuda_probe(void)
  {
  #ifdef CONFIG_PPC
      if (sys_ctrler != SYS_CTRLER_CUDA)
  	return -ENODEV;
  #else
      if (macintosh_config->adb_type != MAC_ADB_CUDA)
  	return -ENODEV;

  #endif

      if (via == NULL)
  	return -ENODEV;
      return 0;

  }
  #endif /* CONFIG_ADB */
  
  #define WAIT_FOR(cond, what)					\
      do {                                                        \
      	int x;							\
  	for (x = 1000; !(cond); --x) {				\
  	    if (x == 0) {					\
  		printk("Timeout waiting for " what "
  ");	\
  		return -ENXIO;					\
  	    }							\
  	    udelay(100);					\
  	}							\
      } while (0)
  
  static int
  cuda_init_via(void)
  {
      out_8(&via[DIRB], (in_8(&via[DIRB]) | TACK | TIP) & ~TREQ);	/* TACK & TIP out */
      out_8(&via[B], in_8(&via[B]) | TACK | TIP);			/* negate them */
      out_8(&via[ACR] ,(in_8(&via[ACR]) & ~SR_CTRL) | SR_EXT);	/* SR data in */
      (void)in_8(&via[SR]);						/* clear any left-over data */

  #ifdef CONFIG_PPC

      out_8(&via[IER], 0x7f);					/* disable interrupts from VIA */
      (void)in_8(&via[IER]);

  #else
      out_8(&via[IER], SR_INT);					/* disable SR interrupt from VIA */

  #endif
  
      /* delay 4ms and then clear any pending interrupt */
      mdelay(4);
      (void)in_8(&via[SR]);

      out_8(&via[IFR], SR_INT);

  
      /* sync with the CUDA - assert TACK without TIP */
      out_8(&via[B], in_8(&via[B]) & ~TACK);
  
      /* wait for the CUDA to assert TREQ in response */
      WAIT_FOR((in_8(&via[B]) & TREQ) == 0, "CUDA response to sync");
  
      /* wait for the interrupt and then clear it */
      WAIT_FOR(in_8(&via[IFR]) & SR_INT, "CUDA response to sync (2)");
      (void)in_8(&via[SR]);

      out_8(&via[IFR], SR_INT);

  
      /* finish the sync by negating TACK */
      out_8(&via[B], in_8(&via[B]) | TACK);
  
      /* wait for the CUDA to negate TREQ and the corresponding interrupt */
      WAIT_FOR(in_8(&via[B]) & TREQ, "CUDA response to sync (3)");
      WAIT_FOR(in_8(&via[IFR]) & SR_INT, "CUDA response to sync (4)");
      (void)in_8(&via[SR]);

      out_8(&via[IFR], SR_INT);

      out_8(&via[B], in_8(&via[B]) | TIP);	/* should be unnecessary */
  
      return 0;
  }
  
  #ifdef CONFIG_ADB
  /* Send an ADB command */
  static int
  cuda_send_request(struct adb_request *req, int sync)
  {
      int i;
  
      if ((via == NULL) || !cuda_fully_inited) {
  	req->complete = 1;
  	return -ENXIO;
      }
    
      req->reply_expected = 1;
  
      i = cuda_write(req);
      if (i)
  	return i;
  
      if (sync) {
  	while (!req->complete)
  	    cuda_poll();
      }
      return 0;
  }
  
  
  /* Enable/disable autopolling */
  static int
  cuda_adb_autopoll(int devs)
  {
      struct adb_request req;
  
      if ((via == NULL) || !cuda_fully_inited)
  	return -ENXIO;
  
      cuda_request(&req, NULL, 3, CUDA_PACKET, CUDA_AUTOPOLL, (devs? 1: 0));
      while (!req.complete)
  	cuda_poll();
      return 0;
  }
  
  /* Reset adb bus - how do we do this?? */
  static int
  cuda_reset_adb_bus(void)
  {
      struct adb_request req;
  
      if ((via == NULL) || !cuda_fully_inited)
  	return -ENXIO;
  
      cuda_request(&req, NULL, 2, ADB_PACKET, 0);		/* maybe? */
      while (!req.complete)
  	cuda_poll();
      return 0;
  }
  #endif /* CONFIG_ADB */
  /* Construct and send a cuda request */
  int
  cuda_request(struct adb_request *req, void (*done)(struct adb_request *),
  	     int nbytes, ...)
  {
      va_list list;
      int i;
  
      if (via == NULL) {
  	req->complete = 1;
  	return -ENXIO;
      }
  
      req->nbytes = nbytes;
      req->done = done;
      va_start(list, nbytes);
      for (i = 0; i < nbytes; ++i)
  	req->data[i] = va_arg(list, int);
      va_end(list);
      req->reply_expected = 1;
      return cuda_write(req);
  }
  
  static int
  cuda_write(struct adb_request *req)
  {
      unsigned long flags;
  
      if (req->nbytes < 2 || req->data[0] > CUDA_PACKET) {
  	req->complete = 1;
  	return -EINVAL;
      }
      req->next = NULL;
      req->sent = 0;
      req->complete = 0;
      req->reply_len = 0;
  
      spin_lock_irqsave(&cuda_lock, flags);
      if (current_req != 0) {
  	last_req->next = req;
  	last_req = req;
      } else {
  	current_req = req;
  	last_req = req;
  	if (cuda_state == idle)
  	    cuda_start();
      }
      spin_unlock_irqrestore(&cuda_lock, flags);
  
      return 0;
  }
  
  static void
  cuda_start(void)
  {
      struct adb_request *req;
  
      /* assert cuda_state == idle */
      /* get the packet to send */
      req = current_req;
      if (req == 0)
  	return;
      if ((in_8(&via[B]) & TREQ) == 0)
  	return;			/* a byte is coming in from the CUDA */
  
      /* set the shift register to shift out and send a byte */
      out_8(&via[ACR], in_8(&via[ACR]) | SR_OUT);
      out_8(&via[SR], req->data[0]);
      out_8(&via[B], in_8(&via[B]) & ~TIP);
      cuda_state = sent_first_byte;
  }
  
  void
  cuda_poll(void)
  {

      /* cuda_interrupt only takes a normal lock, we disable
       * interrupts here to avoid re-entering and thus deadlocking.

       */

      if (cuda_irq)
  	disable_irq(cuda_irq);

      cuda_interrupt(0, NULL);

      if (cuda_irq)
  	enable_irq(cuda_irq);

  }
  
  static irqreturn_t

  cuda_interrupt(int irq, void *arg)

  {
      int status;
      struct adb_request *req = NULL;
      unsigned char ibuf[16];
      int ibuf_len = 0;
      int complete = 0;

      
      spin_lock(&cuda_lock);

      /* On powermacs, this handler is registered for the VIA IRQ. But they use

       * just the shift register IRQ -- other VIA interrupt sources are disabled.
       * On m68k macs, the VIA IRQ sources are dispatched individually. Unless
       * we are polling, the shift register IRQ flag has already been cleared.
       */
  
  #ifdef CONFIG_MAC
      if (!arg)
  #endif
      {
          if ((in_8(&via[IFR]) & SR_INT) == 0) {
              spin_unlock(&cuda_lock);
              return IRQ_NONE;
          } else {
              out_8(&via[IFR], SR_INT);
          }

      }
      
      status = (~in_8(&via[B]) & (TIP|TREQ)) | (in_8(&via[ACR]) & SR_OUT);
      /* printk("cuda_interrupt: state=%d status=%x
  ", cuda_state, status); */
      switch (cuda_state) {
      case idle:
  	/* CUDA has sent us the first byte of data - unsolicited */
  	if (status != TREQ)
  	    printk("cuda: state=idle, status=%x
  ", status);
  	(void)in_8(&via[SR]);
  	out_8(&via[B], in_8(&via[B]) & ~TIP);
  	cuda_state = reading;
  	reply_ptr = cuda_rbuf;
  	reading_reply = 0;
  	break;
  
      case awaiting_reply:
  	/* CUDA has sent us the first byte of data of a reply */
  	if (status != TREQ)
  	    printk("cuda: state=awaiting_reply, status=%x
  ", status);
  	(void)in_8(&via[SR]);
  	out_8(&via[B], in_8(&via[B]) & ~TIP);
  	cuda_state = reading;
  	reply_ptr = current_req->reply;
  	reading_reply = 1;
  	break;
  
      case sent_first_byte:
  	if (status == TREQ + TIP + SR_OUT) {
  	    /* collision */
  	    out_8(&via[ACR], in_8(&via[ACR]) & ~SR_OUT);
  	    (void)in_8(&via[SR]);
  	    out_8(&via[B], in_8(&via[B]) | TIP | TACK);
  	    cuda_state = idle;
  	} else {
  	    /* assert status == TIP + SR_OUT */
  	    if (status != TIP + SR_OUT)
  		printk("cuda: state=sent_first_byte status=%x
  ", status);
  	    out_8(&via[SR], current_req->data[1]);
  	    out_8(&via[B], in_8(&via[B]) ^ TACK);
  	    data_index = 2;
  	    cuda_state = sending;
  	}
  	break;
  
      case sending:
  	req = current_req;
  	if (data_index >= req->nbytes) {
  	    out_8(&via[ACR], in_8(&via[ACR]) & ~SR_OUT);
  	    (void)in_8(&via[SR]);
  	    out_8(&via[B], in_8(&via[B]) | TACK | TIP);
  	    req->sent = 1;
  	    if (req->reply_expected) {
  		cuda_state = awaiting_reply;
  	    } else {
  		current_req = req->next;
  		complete = 1;
  		/* not sure about this */
  		cuda_state = idle;
  		cuda_start();
  	    }
  	} else {
  	    out_8(&via[SR], req->data[data_index++]);
  	    out_8(&via[B], in_8(&via[B]) ^ TACK);
  	}
  	break;
  
      case reading:
  	*reply_ptr++ = in_8(&via[SR]);
  	if (status == TIP) {
  	    /* that's all folks */
  	    out_8(&via[B], in_8(&via[B]) | TACK | TIP);
  	    cuda_state = read_done;
  	} else {
  	    /* assert status == TIP | TREQ */
  	    if (status != TIP + TREQ)
  		printk("cuda: state=reading status=%x
  ", status);
  	    out_8(&via[B], in_8(&via[B]) ^ TACK);
  	}
  	break;
  
      case read_done:
  	(void)in_8(&via[SR]);
  	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);
  		}
  	    }
  	    current_req = req->next;
  	    complete = 1;
  	} else {
  	    /* This is tricky. We must break the spinlock to call
  	     * cuda_input. However, doing so means we might get
  	     * re-entered from another CPU getting an interrupt
  	     * or calling cuda_poll(). I ended up using the stack
  	     * (it's only for 16 bytes) and moving the actual
  	     * call to cuda_input to outside of the lock.
  	     */
  	    ibuf_len = reply_ptr - cuda_rbuf;
  	    memcpy(ibuf, cuda_rbuf, ibuf_len);
  	}
  	if (status == TREQ) {
  	    out_8(&via[B], in_8(&via[B]) & ~TIP);
  	    cuda_state = reading;
  	    reply_ptr = cuda_rbuf;
  	    reading_reply = 0;
  	} else {
  	    cuda_state = idle;
  	    cuda_start();
  	}
  	break;
  
      default:
  	printk("cuda_interrupt: unknown cuda_state %d?
  ", cuda_state);
      }
      spin_unlock(&cuda_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)

  	cuda_input(ibuf, ibuf_len);

      return IRQ_HANDLED;
  }
  
  static void

  cuda_input(unsigned char *buf, int nb)

  {
      int i;
  
      switch (buf[0]) {
      case ADB_PACKET:
  #ifdef CONFIG_XMON
  	if (nb == 5 && buf[2] == 0x2c) {
  	    extern int xmon_wants_key, xmon_adb_keycode;
  	    if (xmon_wants_key) {
  		xmon_adb_keycode = buf[3];
  		return;
  	    }
  	}
  #endif /* CONFIG_XMON */
  #ifdef CONFIG_ADB

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

  #endif /* CONFIG_ADB */
  	break;
  
      default:
  	printk("data from cuda (%d bytes):", nb);
  	for (i = 0; i < nb; ++i)
  	    printk(" %.2x", buf[i]);
  	printk("
  ");
      }
  }