/*
   * I/O Processor (IOP) management
   * Written and (C) 1999 by Joshua M. Thompson (funaho@jurai.org)
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   * 1. Redistributions of source code must retain the above copyright
   *    notice and this list of conditions.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice and this list of conditions in the documentation and/or other
   *    materials provided with the distribution.
   */
  
  /*
   * The IOP chips are used in the IIfx and some Quadras (900, 950) to manage
   * serial and ADB. They are actually a 6502 processor and some glue logic.
   *
   * 990429 (jmt) - Initial implementation, just enough to knock the SCC IOP
   *		  into compatible mode so nobody has to fiddle with the
   *		  Serial Switch control panel anymore.
   * 990603 (jmt) - Added code to grab the correct ISM IOP interrupt for OSS
   *		  and non-OSS machines (at least I hope it's correct on a
   *		  non-OSS machine -- someone with a Q900 or Q950 needs to
   *		  check this.)
   * 990605 (jmt) - Rearranged things a bit wrt IOP detection; iop_present is
   *		  gone, IOP base addresses are now in an array and the
   *		  globally-visible functions take an IOP number instead of an
   *		  an actual base address.
   * 990610 (jmt) - Finished the message passing framework and it seems to work.
   *		  Sending _definitely_ works; my adb-bus.c mods can send
   *		  messages and receive the MSG_COMPLETED status back from the
   *		  IOP. The trick now is figuring out the message formats.
   * 990611 (jmt) - More cleanups. Fixed problem where unclaimed messages on a
   *		  receive channel were never properly acknowledged. Bracketed
   *		  the remaining debug printk's with #ifdef's and disabled
   *		  debugging. I can now type on the console.
   * 990612 (jmt) - Copyright notice added. Reworked the way replies are handled.
   *		  It turns out that replies are placed back in the send buffer
   *		  for that channel; messages on the receive channels are always
   *		  unsolicited messages from the IOP (and our replies to them
   *		  should go back in the receive channel.) Also added tracking
   *		  of device names to the listener functions ala the interrupt
   *		  handlers.
   * 990729 (jmt) - Added passing of pt_regs structure to IOP handlers. This is
   *		  used by the new unified ADB driver.
   *
   * TODO:
   *
   * o Something should be periodically checking iop_alive() to make sure the
   *   IOP hasn't died.
   * o Some of the IOP manager routines need better error checking and
   *   return codes. Nothing major, just prettying up.
   */
  
  /*
   * -----------------------
   * IOP Message Passing 101
   * -----------------------
   *
   * The host talks to the IOPs using a rather simple message-passing scheme via
   * a shared memory area in the IOP RAM. Each IOP has seven "channels"; each
   * channel is conneced to a specific software driver on the IOP. For example
   * on the SCC IOP there is one channel for each serial port. Each channel has
   * an incoming and and outgoing message queue with a depth of one.
   *
   * A message is 32 bytes plus a state byte for the channel (MSG_IDLE, MSG_NEW,
   * MSG_RCVD, MSG_COMPLETE). To send a message you copy the message into the
   * buffer, set the state to MSG_NEW and signal the IOP by setting the IRQ flag
   * in the IOP control to 1. The IOP will move the state to MSG_RCVD when it
   * receives the message and then to MSG_COMPLETE when the message processing
   * has completed. It is the host's responsibility at that point to read the
   * reply back out of the send channel buffer and reset the channel state back
   * to MSG_IDLE.
   *
   * To receive message from the IOP the same procedure is used except the roles
   * are reversed. That is, the IOP puts message in the channel with a state of
   * MSG_NEW, and the host receives the message and move its state to MSG_RCVD
   * and then to MSG_COMPLETE when processing is completed and the reply (if any)
   * has been placed back in the receive channel. The IOP will then reset the
   * channel state to MSG_IDLE.
   *
   * Two sets of host interrupts are provided, INT0 and INT1. Both appear on one
   * interrupt level; they are distinguished by a pair of bits in the IOP status
   * register. The IOP will raise INT0 when one or more messages in the send
   * channels have gone to the MSG_COMPLETE state and it will raise INT1 when one
   * or more messages on the receive channels have gone to the MSG_NEW state.
   *
   * Since each channel handles only one message we have to implement a small
   * interrupt-driven queue on our end. Messages to be sent are placed on the
   * queue for sending and contain a pointer to an optional callback function.
   * The handler for a message is called when the message state goes to
   * MSG_COMPLETE.
   *
   * For receiving message we maintain a list of handler functions to call when
   * a message is received on that IOP/channel combination. The handlers are
   * called much like an interrupt handler and are passed a copy of the message
   * from the IOP. The message state will be in MSG_RCVD while the handler runs;
   * it is the handler's responsibility to call iop_complete_message() when
   * finished; this function moves the message state to MSG_COMPLETE and signals
   * the IOP. This two-step process is provided to allow the handler to defer
   * message processing to a bottom-half handler if the processing will take
   * a significant amount of time (handlers are called at interrupt time so they
   * should execute quickly.)
   */
  
  #include <linux/types.h>
  #include <linux/kernel.h>
  #include <linux/mm.h>
  #include <linux/delay.h>
  #include <linux/init.h>
  #include <linux/interrupt.h>
  
  #include <asm/macintosh.h>
  #include <asm/macints.h>
  #include <asm/mac_iop.h>
  
  /*#define DEBUG_IOP*/
  
  /* Non-zero if the IOPs are present */
  
  int iop_scc_present, iop_ism_present;
  
  /* structure for tracking channel listeners */
  
  struct listener {
  	const char *devname;
  	void (*handler)(struct iop_msg *);
  };
  
  /*
   * IOP structures for the two IOPs
   *
   * The SCC IOP controls both serial ports (A and B) as its two functions.
   * The ISM IOP controls the SWIM (floppy drive) and ADB.
   */
  
  static volatile struct mac_iop *iop_base[NUM_IOPS];
  
  /*
   * IOP message queues
   */
  
  static struct iop_msg iop_msg_pool[NUM_IOP_MSGS];
  static struct iop_msg *iop_send_queue[NUM_IOPS][NUM_IOP_CHAN];
  static struct listener iop_listeners[NUM_IOPS][NUM_IOP_CHAN];
  
  irqreturn_t iop_ism_irq(int, void *);
  
  /*
   * Private access functions
   */
  
  static __inline__ void iop_loadaddr(volatile struct mac_iop *iop, __u16 addr)
  {
  	iop->ram_addr_lo = addr;
  	iop->ram_addr_hi = addr >> 8;
  }
  
  static __inline__ __u8 iop_readb(volatile struct mac_iop *iop, __u16 addr)
  {
  	iop->ram_addr_lo = addr;
  	iop->ram_addr_hi = addr >> 8;
  	return iop->ram_data;
  }
  
  static __inline__ void iop_writeb(volatile struct mac_iop *iop, __u16 addr, __u8 data)
  {
  	iop->ram_addr_lo = addr;
  	iop->ram_addr_hi = addr >> 8;
  	iop->ram_data = data;
  }
  
  static __inline__ void iop_stop(volatile struct mac_iop *iop)
  {
  	iop->status_ctrl &= ~IOP_RUN;
  }
  
  static __inline__ void iop_start(volatile struct mac_iop *iop)
  {
  	iop->status_ctrl = IOP_RUN | IOP_AUTOINC;
  }
  
  static __inline__ void iop_bypass(volatile struct mac_iop *iop)
  {
  	iop->status_ctrl |= IOP_BYPASS;
  }
  
  static __inline__ void iop_interrupt(volatile struct mac_iop *iop)
  {
  	iop->status_ctrl |= IOP_IRQ;
  }
  
  static int iop_alive(volatile struct mac_iop *iop)
  {
  	int retval;
  
  	retval = (iop_readb(iop, IOP_ADDR_ALIVE) == 0xFF);
  	iop_writeb(iop, IOP_ADDR_ALIVE, 0);
  	return retval;
  }
  
  static struct iop_msg *iop_alloc_msg(void)
  {
  	int i;
  	unsigned long flags;
  
  	local_irq_save(flags);
  
  	for (i = 0 ; i < NUM_IOP_MSGS ; i++) {
  		if (iop_msg_pool[i].status == IOP_MSGSTATUS_UNUSED) {
  			iop_msg_pool[i].status = IOP_MSGSTATUS_WAITING;
  			local_irq_restore(flags);
  			return &iop_msg_pool[i];
  		}
  	}
  
  	local_irq_restore(flags);
  	return NULL;
  }
  
  static void iop_free_msg(struct iop_msg *msg)
  {
  	msg->status = IOP_MSGSTATUS_UNUSED;
  }
  
  /*
   * This is called by the startup code before anything else. Its purpose
   * is to find and initialize the IOPs early in the boot sequence, so that
   * the serial IOP can be placed into bypass mode _before_ we try to
   * initialize the serial console.
   */
  
  void __init iop_preinit(void)
  {
  	if (macintosh_config->scc_type == MAC_SCC_IOP) {
  		if (macintosh_config->ident == MAC_MODEL_IIFX) {
  			iop_base[IOP_NUM_SCC] = (struct mac_iop *) SCC_IOP_BASE_IIFX;
  		} else {
  			iop_base[IOP_NUM_SCC] = (struct mac_iop *) SCC_IOP_BASE_QUADRA;
  		}
  		iop_base[IOP_NUM_SCC]->status_ctrl = 0x87;
  		iop_scc_present = 1;
  	} else {
  		iop_base[IOP_NUM_SCC] = NULL;
  		iop_scc_present = 0;
  	}
  	if (macintosh_config->adb_type == MAC_ADB_IOP) {
  		if (macintosh_config->ident == MAC_MODEL_IIFX) {
  			iop_base[IOP_NUM_ISM] = (struct mac_iop *) ISM_IOP_BASE_IIFX;
  		} else {
  			iop_base[IOP_NUM_ISM] = (struct mac_iop *) ISM_IOP_BASE_QUADRA;
  		}
  		iop_base[IOP_NUM_ISM]->status_ctrl = 0;
  		iop_ism_present = 1;
  	} else {
  		iop_base[IOP_NUM_ISM] = NULL;
  		iop_ism_present = 0;
  	}
  }
  
  /*
   * Initialize the IOPs, if present.
   */
  
  void __init iop_init(void)
  {
  	int i;
  
  	if (iop_scc_present) {
  		printk("IOP: detected SCC IOP at %p
  ", iop_base[IOP_NUM_SCC]);
  	}
  	if (iop_ism_present) {
  		printk("IOP: detected ISM IOP at %p
  ", iop_base[IOP_NUM_ISM]);
  		iop_start(iop_base[IOP_NUM_ISM]);
  		iop_alive(iop_base[IOP_NUM_ISM]); /* clears the alive flag */
  	}
  
  	/* Make the whole pool available and empty the queues */
  
  	for (i = 0 ; i < NUM_IOP_MSGS ; i++) {
  		iop_msg_pool[i].status = IOP_MSGSTATUS_UNUSED;
  	}
  
  	for (i = 0 ; i < NUM_IOP_CHAN ; i++) {
  		iop_send_queue[IOP_NUM_SCC][i] = NULL;
  		iop_send_queue[IOP_NUM_ISM][i] = NULL;
  		iop_listeners[IOP_NUM_SCC][i].devname = NULL;
  		iop_listeners[IOP_NUM_SCC][i].handler = NULL;
  		iop_listeners[IOP_NUM_ISM][i].devname = NULL;
  		iop_listeners[IOP_NUM_ISM][i].handler = NULL;
  	}
  }
  
  /*
   * Register the interrupt handler for the IOPs.
   * TODO: might be wrong for non-OSS machines. Anyone?
   */
  
  void __init iop_register_interrupts(void)
  {
  	if (iop_ism_present) {
  		if (macintosh_config->ident == MAC_MODEL_IIFX) {
  			if (request_irq(IRQ_MAC_ADB, iop_ism_irq, 0,
  					"ISM IOP", (void *)IOP_NUM_ISM))
  				pr_err("Couldn't register ISM IOP interrupt
  ");
  		} else {
  			if (request_irq(IRQ_VIA2_0, iop_ism_irq, 0, "ISM IOP",
  					(void *)IOP_NUM_ISM))
  				pr_err("Couldn't register ISM IOP interrupt
  ");
  		}
  		if (!iop_alive(iop_base[IOP_NUM_ISM])) {
  			printk("IOP: oh my god, they killed the ISM IOP!
  ");
  		} else {
  			printk("IOP: the ISM IOP seems to be alive.
  ");
  		}
  	}
  }
  
  /*
   * Register or unregister a listener for a specific IOP and channel
   *
   * If the handler pointer is NULL the current listener (if any) is
   * unregistered. Otherwise the new listener is registered provided
   * there is no existing listener registered.
   */
  
  int iop_listen(uint iop_num, uint chan,
  		void (*handler)(struct iop_msg *),
  		const char *devname)
  {
  	if ((iop_num >= NUM_IOPS) || !iop_base[iop_num]) return -EINVAL;
  	if (chan >= NUM_IOP_CHAN) return -EINVAL;
  	if (iop_listeners[iop_num][chan].handler && handler) return -EINVAL;
  	iop_listeners[iop_num][chan].devname = devname;
  	iop_listeners[iop_num][chan].handler = handler;
  	return 0;
  }
  
  /*
   * Complete reception of a message, which just means copying the reply
   * into the buffer, setting the channel state to MSG_COMPLETE and
   * notifying the IOP.
   */
  
  void iop_complete_message(struct iop_msg *msg)
  {
  	int iop_num = msg->iop_num;
  	int chan = msg->channel;
  	int i,offset;
  
  #ifdef DEBUG_IOP
  	printk("iop_complete(%p): iop %d chan %d
  ", msg, msg->iop_num, msg->channel);
  #endif
  
  	offset = IOP_ADDR_RECV_MSG + (msg->channel * IOP_MSG_LEN);
  
  	for (i = 0 ; i < IOP_MSG_LEN ; i++, offset++) {
  		iop_writeb(iop_base[iop_num], offset, msg->reply[i]);
  	}
  
  	iop_writeb(iop_base[iop_num],
  		   IOP_ADDR_RECV_STATE + chan, IOP_MSG_COMPLETE);
  	iop_interrupt(iop_base[msg->iop_num]);
  
  	iop_free_msg(msg);
  }
  
  /*
   * Actually put a message into a send channel buffer
   */
  
  static void iop_do_send(struct iop_msg *msg)
  {
  	volatile struct mac_iop *iop = iop_base[msg->iop_num];
  	int i,offset;
  
  	offset = IOP_ADDR_SEND_MSG + (msg->channel * IOP_MSG_LEN);
  
  	for (i = 0 ; i < IOP_MSG_LEN ; i++, offset++) {
  		iop_writeb(iop, offset, msg->message[i]);
  	}
  
  	iop_writeb(iop, IOP_ADDR_SEND_STATE + msg->channel, IOP_MSG_NEW);
  
  	iop_interrupt(iop);
  }
  
  /*
   * Handle sending a message on a channel that
   * has gone into the IOP_MSG_COMPLETE state.
   */
  
  static void iop_handle_send(uint iop_num, uint chan)
  {
  	volatile struct mac_iop *iop = iop_base[iop_num];
  	struct iop_msg *msg,*msg2;
  	int i,offset;
  
  #ifdef DEBUG_IOP
  	printk("iop_handle_send: iop %d channel %d
  ", iop_num, chan);
  #endif
  
  	iop_writeb(iop, IOP_ADDR_SEND_STATE + chan, IOP_MSG_IDLE);
  
  	if (!(msg = iop_send_queue[iop_num][chan])) return;
  
  	msg->status = IOP_MSGSTATUS_COMPLETE;
  	offset = IOP_ADDR_SEND_MSG + (chan * IOP_MSG_LEN);
  	for (i = 0 ; i < IOP_MSG_LEN ; i++, offset++) {
  		msg->reply[i] = iop_readb(iop, offset);
  	}
  	if (msg->handler) (*msg->handler)(msg);
  	msg2 = msg;
  	msg = msg->next;
  	iop_free_msg(msg2);
  
  	iop_send_queue[iop_num][chan] = msg;
  	if (msg) iop_do_send(msg);
  }
  
  /*
   * Handle reception of a message on a channel that has
   * gone into the IOP_MSG_NEW state.
   */
  
  static void iop_handle_recv(uint iop_num, uint chan)
  {
  	volatile struct mac_iop *iop = iop_base[iop_num];
  	int i,offset;
  	struct iop_msg *msg;
  
  #ifdef DEBUG_IOP
  	printk("iop_handle_recv: iop %d channel %d
  ", iop_num, chan);
  #endif
  
  	msg = iop_alloc_msg();
  	msg->iop_num = iop_num;
  	msg->channel = chan;
  	msg->status = IOP_MSGSTATUS_UNSOL;
  	msg->handler = iop_listeners[iop_num][chan].handler;
  
  	offset = IOP_ADDR_RECV_MSG + (chan * IOP_MSG_LEN);
  
  	for (i = 0 ; i < IOP_MSG_LEN ; i++, offset++) {
  		msg->message[i] = iop_readb(iop, offset);
  	}
  
  	iop_writeb(iop, IOP_ADDR_RECV_STATE + chan, IOP_MSG_RCVD);
  
  	/* If there is a listener, call it now. Otherwise complete */
  	/* the message ourselves to avoid possible stalls.         */
  
  	if (msg->handler) {
  		(*msg->handler)(msg);
  	} else {
  #ifdef DEBUG_IOP
  		printk("iop_handle_recv: unclaimed message on iop %d channel %d
  ", iop_num, chan);
  		printk("iop_handle_recv:");
  		for (i = 0 ; i < IOP_MSG_LEN ; i++) {
  			printk(" %02X", (uint) msg->message[i]);
  		}
  		printk("
  ");
  #endif
  		iop_complete_message(msg);
  	}
  }
  
  /*
   * Send a message
   *
   * The message is placed at the end of the send queue. Afterwards if the
   * channel is idle we force an immediate send of the next message in the
   * queue.
   */
  
  int iop_send_message(uint iop_num, uint chan, void *privdata,
  		      uint msg_len, __u8 *msg_data,
  		      void (*handler)(struct iop_msg *))
  {
  	struct iop_msg *msg, *q;
  
  	if ((iop_num >= NUM_IOPS) || !iop_base[iop_num]) return -EINVAL;
  	if (chan >= NUM_IOP_CHAN) return -EINVAL;
  	if (msg_len > IOP_MSG_LEN) return -EINVAL;
  
  	msg = iop_alloc_msg();
  	if (!msg) return -ENOMEM;
  
  	msg->next = NULL;
  	msg->status = IOP_MSGSTATUS_WAITING;
  	msg->iop_num = iop_num;
  	msg->channel = chan;
  	msg->caller_priv = privdata;
  	memcpy(msg->message, msg_data, msg_len);
  	msg->handler = handler;
  
  	if (!(q = iop_send_queue[iop_num][chan])) {
  		iop_send_queue[iop_num][chan] = msg;
  	} else {
  		while (q->next) q = q->next;
  		q->next = msg;
  	}
  
  	if (iop_readb(iop_base[iop_num],
  	    IOP_ADDR_SEND_STATE + chan) == IOP_MSG_IDLE) {
  		iop_do_send(msg);
  	}
  
  	return 0;
  }
  
  /*
   * Upload code to the shared RAM of an IOP.
   */
  
  void iop_upload_code(uint iop_num, __u8 *code_start,
  		     uint code_len, __u16 shared_ram_start)
  {
  	if ((iop_num >= NUM_IOPS) || !iop_base[iop_num]) return;
  
  	iop_loadaddr(iop_base[iop_num], shared_ram_start);
  
  	while (code_len--) {
  		iop_base[iop_num]->ram_data = *code_start++;
  	}
  }
  
  /*
   * Download code from the shared RAM of an IOP.
   */
  
  void iop_download_code(uint iop_num, __u8 *code_start,
  		       uint code_len, __u16 shared_ram_start)
  {
  	if ((iop_num >= NUM_IOPS) || !iop_base[iop_num]) return;
  
  	iop_loadaddr(iop_base[iop_num], shared_ram_start);
  
  	while (code_len--) {
  		*code_start++ = iop_base[iop_num]->ram_data;
  	}
  }
  
  /*
   * Compare the code in the shared RAM of an IOP with a copy in system memory
   * and return 0 on match or the first nonmatching system memory address on
   * failure.
   */
  
  __u8 *iop_compare_code(uint iop_num, __u8 *code_start,
  		       uint code_len, __u16 shared_ram_start)
  {
  	if ((iop_num >= NUM_IOPS) || !iop_base[iop_num]) return code_start;
  
  	iop_loadaddr(iop_base[iop_num], shared_ram_start);
  
  	while (code_len--) {
  		if (*code_start != iop_base[iop_num]->ram_data) {
  			return code_start;
  		}
  		code_start++;
  	}
  	return (__u8 *) 0;
  }
  
  /*
   * Handle an ISM IOP interrupt
   */
  
  irqreturn_t iop_ism_irq(int irq, void *dev_id)
  {
  	uint iop_num = (uint) dev_id;
  	volatile struct mac_iop *iop = iop_base[iop_num];
  	int i,state;
  
  #ifdef DEBUG_IOP
  	printk("iop_ism_irq: status = %02X
  ", (uint) iop->status_ctrl);
  #endif
  
  	/* INT0 indicates a state change on an outgoing message channel */
  
  	if (iop->status_ctrl & IOP_INT0) {
  		iop->status_ctrl = IOP_INT0 | IOP_RUN | IOP_AUTOINC;
  #ifdef DEBUG_IOP
  		printk("iop_ism_irq: new status = %02X, send states",
  			(uint) iop->status_ctrl);
  #endif
  		for (i = 0 ; i < NUM_IOP_CHAN  ; i++) {
  			state = iop_readb(iop, IOP_ADDR_SEND_STATE + i);
  #ifdef DEBUG_IOP
  			printk(" %02X", state);
  #endif
  			if (state == IOP_MSG_COMPLETE) {
  				iop_handle_send(iop_num, i);
  			}
  		}
  #ifdef DEBUG_IOP
  		printk("
  ");
  #endif
  	}
  
  	if (iop->status_ctrl & IOP_INT1) {	/* INT1 for incoming msgs */
  		iop->status_ctrl = IOP_INT1 | IOP_RUN | IOP_AUTOINC;
  #ifdef DEBUG_IOP
  		printk("iop_ism_irq: new status = %02X, recv states",
  			(uint) iop->status_ctrl);
  #endif
  		for (i = 0 ; i < NUM_IOP_CHAN ; i++) {
  			state = iop_readb(iop, IOP_ADDR_RECV_STATE + i);
  #ifdef DEBUG_IOP
  			printk(" %02X", state);
  #endif
  			if (state == IOP_MSG_NEW) {
  				iop_handle_recv(iop_num, i);
  			}
  		}
  #ifdef DEBUG_IOP
  		printk("
  ");
  #endif
  	}
  	return IRQ_HANDLED;
  }