// 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 enum scsi_qc_status mac53c94_queue_lck(struct scsi_cmnd *cmd)
{
        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 "\n");
                printk(KERN_DEBUG "use_sg=%d request_bufflen=%d request_buffer=%p\n",
                       scsi_sg_count(cmd), scsi_bufflen(cmd), scsi_sglist(cmd));
        }
#endif

        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;

        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);
        (void)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 *const cmd = state->current_req;
        struct mac53c94_cmd_priv *const mcmd = mac53c94_priv(cmd);
        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\n",
               intr, stat, seq, state->phase);
#endif

        if (intr & INTR_RESET) {
                /* SCSI bus was reset */
                printk(KERN_INFO "external SCSI bus reset detected\n");
                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\n",
                       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\n",
                       intr, stat, seq, state->phase);
#endif
                ++mac53c94_errors;
                writeb(CMD_NOP + CMD_DMA_MODE, &regs->command);
        }
        if (!cmd) {
                printk(KERN_DEBUG "53c94: interrupt with no command active?\n");
                return;
        }
        if (stat & STAT_PARITY) {
                printk(KERN_ERR "mac53c94: parity error\n");
                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\n", intr);
                        cmd_done(state, DID_ERROR << 16);
                        return;
                }
                if ((seq & SS_MASK) != SS_DONE) {
                        printk(KERN_DEBUG "seq step %x after command\n", 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 = mcmd->this_residual;
                        if (nb > 0xfff0)
                                nb = 0xfff0;
                        mcmd->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\n",
                               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\n", intr);
                        cmd_done(state, DID_ERROR << 16);
                        return;
                }
                if (mcmd->this_residual != 0
                    && (stat & (STAT_MSG|STAT_CD)) == 0) {
                        /* Set up the count regs to transfer more */
                        nb = mcmd->this_residual;
                        if (nb > 0xfff0)
                                nb = 0xfff0;
                        mcmd->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\n", 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\n", intr);
                        cmd_done(state, DID_ERROR << 16);
                        return;
                }
                mcmd->status = readb(&regs->fifo);
                mcmd->message = readb(&regs->fifo);
                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\n", intr);
                }
                cmd_done(state, (DID_OK << 16) + (mcmd->message << 8) + mcmd->status);
                break;
        default:
                printk(KERN_DEBUG "don't know about phase %d\n", state->phase);
        }
}

static void cmd_done(struct fsc_state *state, int result)
{
        struct scsi_cmnd *cmd;

        cmd = state->current_req;
        if (cmd) {
                cmd->result = result;
                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);
        mac53c94_priv(cmd)->this_residual = total;
}

static const 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,
        .cmd_size       = sizeof(struct mac53c94_cmd_priv),
};

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)\n",
                       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\n", 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\n", 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_objs(struct dbdma_cmd,
                                            host->sg_tablesize + 2);
        if (!dma_cmd_space) {
                printk(KERN_ERR "mac53c94: couldn't allocate dma "
                       "command space for %pOF\n", 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\n",
                       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 void 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);
}

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");