// SPDX-License-Identifier: GPL-2.0-only

  /*
   * SCSI low-level driver for the 53c94 SCSI bus adaptor found
   * on Power Macintosh computers, controlling the external SCSI chain.
   * We assume the 53c94 is connected to a DBDMA (descriptor-based DMA)
   * controller.
   *
   * Paul Mackerras, August 1996.
   * Copyright (C) 1996 Paul Mackerras.
   */
  #include <linux/kernel.h>
  #include <linux/delay.h>
  #include <linux/types.h>
  #include <linux/string.h>
  #include <linux/slab.h>
  #include <linux/blkdev.h>
  #include <linux/proc_fs.h>
  #include <linux/stat.h>
  #include <linux/spinlock.h>
  #include <linux/interrupt.h>

  #include <linux/module.h>

  #include <linux/pci.h>

  #include <linux/pgtable.h>

  #include <asm/dbdma.h>
  #include <asm/io.h>

  #include <asm/prom.h>

  #include <asm/macio.h>
  
  #include <scsi/scsi.h>
  #include <scsi/scsi_cmnd.h>
  #include <scsi/scsi_device.h>
  #include <scsi/scsi_host.h>
  
  #include "mac53c94.h"
  
  enum fsc_phase {
  	idle,
  	selecting,
  	dataing,
  	completing,
  	busfreeing,
  };
  
  struct fsc_state {
  	struct	mac53c94_regs __iomem *regs;
  	int	intr;
  	struct	dbdma_regs __iomem *dma;
  	int	dmaintr;
  	int	clk_freq;
  	struct	Scsi_Host *host;
  	struct scsi_cmnd *request_q;
  	struct scsi_cmnd *request_qtail;
  	struct scsi_cmnd *current_req;		/* req we're currently working on */
  	enum fsc_phase phase;		/* what we're currently trying to do */
  	struct dbdma_cmd *dma_cmds;	/* space for dbdma commands, aligned */
  	void	*dma_cmd_space;
  	struct	pci_dev *pdev;
  	dma_addr_t dma_addr;
  	struct macio_dev *mdev;
  };
  
  static void mac53c94_init(struct fsc_state *);
  static void mac53c94_start(struct fsc_state *);

  static void mac53c94_interrupt(int, void *);
  static irqreturn_t do_mac53c94_interrupt(int, void *);

  static void cmd_done(struct fsc_state *, int result);
  static void set_dma_cmds(struct fsc_state *, struct scsi_cmnd *);

  static int mac53c94_queue_lck(struct scsi_cmnd *cmd, void (*done)(struct scsi_cmnd *))

  {
  	struct fsc_state *state;
  
  #if 0
  	if (cmd->sc_data_direction == DMA_TO_DEVICE) {
  		int i;
  		printk(KERN_DEBUG "mac53c94_queue %p: command is", cmd);
  		for (i = 0; i < cmd->cmd_len; ++i)

  			printk(KERN_CONT " %.2x", cmd->cmnd[i]);
  		printk(KERN_CONT "
  ");
  		printk(KERN_DEBUG "use_sg=%d request_bufflen=%d request_buffer=%p
  ",

  		       scsi_sg_count(cmd), scsi_bufflen(cmd), scsi_sglist(cmd));

  	}
  #endif
  
  	cmd->scsi_done = done;
  	cmd->host_scribble = NULL;
  
  	state = (struct fsc_state *) cmd->device->host->hostdata;
  
  	if (state->request_q == NULL)
  		state->request_q = cmd;
  	else
  		state->request_qtail->host_scribble = (void *) cmd;
  	state->request_qtail = cmd;
  
  	if (state->phase == idle)
  		mac53c94_start(state);
  
  	return 0;
  }

  static DEF_SCSI_QCMD(mac53c94_queue)

  static int mac53c94_host_reset(struct scsi_cmnd *cmd)
  {
  	struct fsc_state *state = (struct fsc_state *) cmd->device->host->hostdata;
  	struct mac53c94_regs __iomem *regs = state->regs;
  	struct dbdma_regs __iomem *dma = state->dma;

  	unsigned long flags;
  
  	spin_lock_irqsave(cmd->device->host->host_lock, flags);

  
  	writel((RUN|PAUSE|FLUSH|WAKE) << 16, &dma->control);
  	writeb(CMD_SCSI_RESET, &regs->command);	/* assert RST */
  	udelay(100);			/* leave it on for a while (>= 25us) */
  	writeb(CMD_RESET, &regs->command);
  	udelay(20);
  	mac53c94_init(state);
  	writeb(CMD_NOP, &regs->command);

  
  	spin_unlock_irqrestore(cmd->device->host->host_lock, flags);

  	return SUCCESS;
  }
  
  static void mac53c94_init(struct fsc_state *state)
  {
  	struct mac53c94_regs __iomem *regs = state->regs;
  	struct dbdma_regs __iomem *dma = state->dma;
  	int x;
  
  	writeb(state->host->this_id | CF1_PAR_ENABLE, &regs->config1);
  	writeb(TIMO_VAL(250), &regs->sel_timeout);	/* 250ms */
  	writeb(CLKF_VAL(state->clk_freq), &regs->clk_factor);
  	writeb(CF2_FEATURE_EN, &regs->config2);
  	writeb(0, &regs->config3);
  	writeb(0, &regs->sync_period);
  	writeb(0, &regs->sync_offset);
  	x = readb(&regs->interrupt);
  	writel((RUN|PAUSE|FLUSH|WAKE) << 16, &dma->control);
  }
  
  /*
   * Start the next command for a 53C94.
   * Should be called with interrupts disabled.
   */
  static void mac53c94_start(struct fsc_state *state)
  {
  	struct scsi_cmnd *cmd;
  	struct mac53c94_regs __iomem *regs = state->regs;
  	int i;
  
  	if (state->phase != idle || state->current_req != NULL)
  		panic("inappropriate mac53c94_start (state=%p)", state);
  	if (state->request_q == NULL)
  		return;
  	state->current_req = cmd = state->request_q;
  	state->request_q = (struct scsi_cmnd *) cmd->host_scribble;
  
  	/* Off we go */
  	writeb(0, &regs->count_lo);
  	writeb(0, &regs->count_mid);
  	writeb(0, &regs->count_hi);
  	writeb(CMD_NOP + CMD_DMA_MODE, &regs->command);
  	udelay(1);
  	writeb(CMD_FLUSH, &regs->command);
  	udelay(1);
  	writeb(cmd->device->id, &regs->dest_id);
  	writeb(0, &regs->sync_period);
  	writeb(0, &regs->sync_offset);
  
  	/* load the command into the FIFO */
  	for (i = 0; i < cmd->cmd_len; ++i)
  		writeb(cmd->cmnd[i], &regs->fifo);
  
  	/* do select without ATN XXX */
  	writeb(CMD_SELECT, &regs->command);
  	state->phase = selecting;

  	set_dma_cmds(state, cmd);

  }

  static irqreturn_t do_mac53c94_interrupt(int irq, void *dev_id)

  {
  	unsigned long flags;
  	struct Scsi_Host *dev = ((struct fsc_state *) dev_id)->current_req->device->host;
  	
  	spin_lock_irqsave(dev->host_lock, flags);

  	mac53c94_interrupt(irq, dev_id);

  	spin_unlock_irqrestore(dev->host_lock, flags);
  	return IRQ_HANDLED;
  }

  static void mac53c94_interrupt(int irq, void *dev_id)

  {
  	struct fsc_state *state = (struct fsc_state *) dev_id;
  	struct mac53c94_regs __iomem *regs = state->regs;
  	struct dbdma_regs __iomem *dma = state->dma;
  	struct scsi_cmnd *cmd = state->current_req;
  	int nb, stat, seq, intr;
  	static int mac53c94_errors;
  
  	/*
  	 * Apparently, reading the interrupt register unlatches
  	 * the status and sequence step registers.
  	 */
  	seq = readb(&regs->seqstep);
  	stat = readb(&regs->status);
  	intr = readb(&regs->interrupt);
  
  #if 0
  	printk(KERN_DEBUG "mac53c94_intr, intr=%x stat=%x seq=%x phase=%d
  ",
  	       intr, stat, seq, state->phase);
  #endif
  
  	if (intr & INTR_RESET) {
  		/* SCSI bus was reset */
  		printk(KERN_INFO "external SCSI bus reset detected
  ");
  		writeb(CMD_NOP, &regs->command);
  		writel(RUN << 16, &dma->control);	/* stop dma */
  		cmd_done(state, DID_RESET << 16);
  		return;
  	}
  	if (intr & INTR_ILL_CMD) {
  		printk(KERN_ERR "53c94: invalid cmd, intr=%x stat=%x seq=%x phase=%d
  ",
  		       intr, stat, seq, state->phase);
  		cmd_done(state, DID_ERROR << 16);
  		return;
  	}
  	if (stat & STAT_ERROR) {
  #if 0
  		/* XXX these seem to be harmless? */
  		printk("53c94: bad error, intr=%x stat=%x seq=%x phase=%d
  ",
  		       intr, stat, seq, state->phase);
  #endif
  		++mac53c94_errors;
  		writeb(CMD_NOP + CMD_DMA_MODE, &regs->command);
  	}
  	if (cmd == 0) {
  		printk(KERN_DEBUG "53c94: interrupt with no command active?
  ");
  		return;
  	}
  	if (stat & STAT_PARITY) {
  		printk(KERN_ERR "mac53c94: parity error
  ");
  		cmd_done(state, DID_PARITY << 16);
  		return;
  	}
  	switch (state->phase) {
  	case selecting:
  		if (intr & INTR_DISCONNECT) {
  			/* selection timed out */
  			cmd_done(state, DID_BAD_TARGET << 16);
  			return;
  		}
  		if (intr != INTR_BUS_SERV + INTR_DONE) {
  			printk(KERN_DEBUG "got intr %x during selection
  ", intr);
  			cmd_done(state, DID_ERROR << 16);
  			return;
  		}
  		if ((seq & SS_MASK) != SS_DONE) {
  			printk(KERN_DEBUG "seq step %x after command
  ", seq);
  			cmd_done(state, DID_ERROR << 16);
  			return;
  		}
  		writeb(CMD_NOP, &regs->command);
  		/* set DMA controller going if any data to transfer */
  		if ((stat & (STAT_MSG|STAT_CD)) == 0

  		    && (scsi_sg_count(cmd) > 0 || scsi_bufflen(cmd))) {

  			nb = cmd->SCp.this_residual;
  			if (nb > 0xfff0)
  				nb = 0xfff0;
  			cmd->SCp.this_residual -= nb;
  			writeb(nb, &regs->count_lo);
  			writeb(nb >> 8, &regs->count_mid);
  			writeb(CMD_DMA_MODE + CMD_NOP, &regs->command);
  			writel(virt_to_phys(state->dma_cmds), &dma->cmdptr);
  			writel((RUN << 16) | RUN, &dma->control);
  			writeb(CMD_DMA_MODE + CMD_XFER_DATA, &regs->command);
  			state->phase = dataing;
  			break;
  		} else if ((stat & STAT_PHASE) == STAT_CD + STAT_IO) {
  			/* up to status phase already */
  			writeb(CMD_I_COMPLETE, &regs->command);
  			state->phase = completing;
  		} else {
  			printk(KERN_DEBUG "in unexpected phase %x after cmd
  ",
  			       stat & STAT_PHASE);
  			cmd_done(state, DID_ERROR << 16);
  			return;
  		}
  		break;
  
  	case dataing:
  		if (intr != INTR_BUS_SERV) {
  			printk(KERN_DEBUG "got intr %x before status
  ", intr);
  			cmd_done(state, DID_ERROR << 16);
  			return;
  		}
  		if (cmd->SCp.this_residual != 0
  		    && (stat & (STAT_MSG|STAT_CD)) == 0) {
  			/* Set up the count regs to transfer more */
  			nb = cmd->SCp.this_residual;
  			if (nb > 0xfff0)
  				nb = 0xfff0;
  			cmd->SCp.this_residual -= nb;
  			writeb(nb, &regs->count_lo);
  			writeb(nb >> 8, &regs->count_mid);
  			writeb(CMD_DMA_MODE + CMD_NOP, &regs->command);
  			writeb(CMD_DMA_MODE + CMD_XFER_DATA, &regs->command);
  			break;
  		}
  		if ((stat & STAT_PHASE) != STAT_CD + STAT_IO) {
  			printk(KERN_DEBUG "intr %x before data xfer complete
  ", intr);
  		}
  		writel(RUN << 16, &dma->control);	/* stop dma */

  		scsi_dma_unmap(cmd);

  		/* should check dma status */
  		writeb(CMD_I_COMPLETE, &regs->command);
  		state->phase = completing;
  		break;
  	case completing:
  		if (intr != INTR_DONE) {
  			printk(KERN_DEBUG "got intr %x on completion
  ", intr);
  			cmd_done(state, DID_ERROR << 16);
  			return;
  		}
  		cmd->SCp.Status = readb(&regs->fifo);
  		cmd->SCp.Message = readb(&regs->fifo);
  		cmd->result = CMD_ACCEPT_MSG;
  		writeb(CMD_ACCEPT_MSG, &regs->command);
  		state->phase = busfreeing;
  		break;
  	case busfreeing:
  		if (intr != INTR_DISCONNECT) {
  			printk(KERN_DEBUG "got intr %x when expected disconnect
  ", intr);
  		}
  		cmd_done(state, (DID_OK << 16) + (cmd->SCp.Message << 8)
  			 + cmd->SCp.Status);
  		break;
  	default:
  		printk(KERN_DEBUG "don't know about phase %d
  ", state->phase);
  	}
  }
  
  static void cmd_done(struct fsc_state *state, int result)
  {
  	struct scsi_cmnd *cmd;
  
  	cmd = state->current_req;
  	if (cmd != 0) {
  		cmd->result = result;
  		(*cmd->scsi_done)(cmd);
  		state->current_req = NULL;
  	}
  	state->phase = idle;
  	mac53c94_start(state);
  }
  
  /*
   * Set up DMA commands for transferring data.
   */
  static void set_dma_cmds(struct fsc_state *state, struct scsi_cmnd *cmd)
  {

  	int i, dma_cmd, total, nseg;

  	struct scatterlist *scl;
  	struct dbdma_cmd *dcmds;
  	dma_addr_t dma_addr;
  	u32 dma_len;

  	nseg = scsi_dma_map(cmd);
  	BUG_ON(nseg < 0);
  	if (!nseg)
  		return;

  	dma_cmd = cmd->sc_data_direction == DMA_TO_DEVICE ?
  			OUTPUT_MORE : INPUT_MORE;
  	dcmds = state->dma_cmds;

  	total = 0;
  
  	scsi_for_each_sg(cmd, scl, nseg, i) {
  		dma_addr = sg_dma_address(scl);
  		dma_len = sg_dma_len(scl);
  		if (dma_len > 0xffff)
  			panic("mac53c94: scatterlist element >= 64k");
  		total += dma_len;

  		dcmds->req_count = cpu_to_le16(dma_len);
  		dcmds->command = cpu_to_le16(dma_cmd);
  		dcmds->phy_addr = cpu_to_le32(dma_addr);

  		dcmds->xfer_status = 0;
  		++dcmds;
  	}

  	dma_cmd += OUTPUT_LAST - OUTPUT_MORE;

  	dcmds[-1].command = cpu_to_le16(dma_cmd);
  	dcmds->command = cpu_to_le16(DBDMA_STOP);

  	cmd->SCp.this_residual = total;
  }
  
  static struct scsi_host_template mac53c94_template = {
  	.proc_name	= "53c94",
  	.name		= "53C94",
  	.queuecommand	= mac53c94_queue,

  	.eh_host_reset_handler = mac53c94_host_reset,
  	.can_queue	= 1,
  	.this_id	= 7,
  	.sg_tablesize	= SG_ALL,

  	.max_segment_size = 65535,

  };

  static int mac53c94_probe(struct macio_dev *mdev, const struct of_device_id *match)

  {
  	struct device_node *node = macio_get_of_node(mdev);
  	struct pci_dev *pdev = macio_get_pci_dev(mdev);
  	struct fsc_state *state;
  	struct Scsi_Host *host;
  	void *dma_cmd_space;

  	const unsigned char *clkprop;

  	int proplen, rc = -ENODEV;

  
  	if (macio_resource_count(mdev) != 2 || macio_irq_count(mdev) != 2) {

  		printk(KERN_ERR "mac53c94: expected 2 addrs and intrs"
  		       " (got %d/%d)
  ",
  		       macio_resource_count(mdev), macio_irq_count(mdev));

  		return -ENODEV;
  	}
  
  	if (macio_request_resources(mdev, "mac53c94") != 0) {
         		printk(KERN_ERR "mac53c94: unable to request memory resources");
  		return -EBUSY;
  	}
  
         	host = scsi_host_alloc(&mac53c94_template, sizeof(struct fsc_state));
  	if (host == NULL) {
  		printk(KERN_ERR "mac53c94: couldn't register host");

  		rc = -ENOMEM;

  		goto out_release;
  	}
  
  	state = (struct fsc_state *) host->hostdata;
  	macio_set_drvdata(mdev, state);
  	state->host = host;
  	state->pdev = pdev;
  	state->mdev = mdev;
  
  	state->regs = (struct mac53c94_regs __iomem *)
  		ioremap(macio_resource_start(mdev, 0), 0x1000);
  	state->intr = macio_irq(mdev, 0);
  	state->dma = (struct dbdma_regs __iomem *)
  		ioremap(macio_resource_start(mdev, 1), 0x1000);
  	state->dmaintr = macio_irq(mdev, 1);
  	if (state->regs == NULL || state->dma == NULL) {

  		printk(KERN_ERR "mac53c94: ioremap failed for %pOF
  ", node);

  		goto out_free;
  	}

  	clkprop = of_get_property(node, "clock-frequency", &proplen);

         	if (clkprop == NULL || proplen != sizeof(int)) {

         		printk(KERN_ERR "%pOF: can't get clock frequency, "
         		       "assuming 25MHz
  ", node);

         		state->clk_freq = 25000000;
         	} else
         		state->clk_freq = *(int *)clkprop;
  
         	/* Space for dma command list: +1 for stop command,
         	 * +1 to allow for aligning.
  	 * XXX FIXME: Use DMA consistent routines
  	 */

         	dma_cmd_space = kmalloc_array(host->sg_tablesize + 2,
  					     sizeof(struct dbdma_cmd),
  					     GFP_KERNEL);

         	if (dma_cmd_space == 0) {
         		printk(KERN_ERR "mac53c94: couldn't allocate dma "

         		       "command space for %pOF
  ", node);

  		rc = -ENOMEM;

         		goto out_free;
         	}
  	state->dma_cmds = (struct dbdma_cmd *)DBDMA_ALIGN(dma_cmd_space);
  	memset(state->dma_cmds, 0, (host->sg_tablesize + 1)
  	       * sizeof(struct dbdma_cmd));
  	state->dma_cmd_space = dma_cmd_space;
  
  	mac53c94_init(state);

  	if (request_irq(state->intr, do_mac53c94_interrupt, 0, "53C94",state)) {

  		printk(KERN_ERR "mac53C94: can't get irq %d for %pOF
  ",
  		       state->intr, node);

  		goto out_free_dma;
  	}

  	rc = scsi_add_host(host, &mdev->ofdev.dev);
  	if (rc != 0)
  		goto out_release_irq;

  	scsi_scan_host(host);

  	return 0;

   out_release_irq:
  	free_irq(state->intr, state);

   out_free_dma:
  	kfree(state->dma_cmd_space);
   out_free:
  	if (state->dma != NULL)
  		iounmap(state->dma);
  	if (state->regs != NULL)
  		iounmap(state->regs);
  	scsi_host_put(host);
   out_release:
  	macio_release_resources(mdev);

  	return rc;

  }
  
  static int mac53c94_remove(struct macio_dev *mdev)
  {
  	struct fsc_state *fp = (struct fsc_state *)macio_get_drvdata(mdev);
  	struct Scsi_Host *host = fp->host;
  
  	scsi_remove_host(host);
  
  	free_irq(fp->intr, fp);
  
  	if (fp->regs)

  		iounmap(fp->regs);

  	if (fp->dma)

  		iounmap(fp->dma);

  	kfree(fp->dma_cmd_space);
  
  	scsi_host_put(host);
  
  	macio_release_resources(mdev);
  
  	return 0;
  }

  static struct of_device_id mac53c94_match[] = 

  {
  	{
  	.name 		= "53c94",

  	},
  	{},
  };

  MODULE_DEVICE_TABLE (of, mac53c94_match);

  
  static struct macio_driver mac53c94_driver = 
  {

  	.driver = {
  		.name 		= "mac53c94",
  		.owner		= THIS_MODULE,
  		.of_match_table	= mac53c94_match,
  	},

  	.probe		= mac53c94_probe,
  	.remove		= mac53c94_remove,
  };
  
  
  static int __init init_mac53c94(void)
  {
  	return macio_register_driver(&mac53c94_driver);
  }
  
  static void __exit exit_mac53c94(void)
  {
  	return macio_unregister_driver(&mac53c94_driver);
  }
  
  module_init(init_mac53c94);
  module_exit(exit_mac53c94);
  
  MODULE_DESCRIPTION("PowerMac 53c94 SCSI driver");
  MODULE_AUTHOR("Paul Mackerras <paulus@samba.org>");
  MODULE_LICENSE("GPL");