// SPDX-License-Identifier: GPL-2.0-only
/*
 * Generic Macintosh NCR5380 driver
 *
 * Copyright 1998, Michael Schmitz <mschmitz@lbl.gov>
 *
 * Copyright 2019 Finn Thain
 *
 * derived in part from:
 */
/*
 * Generic Generic NCR5380 driver
 *
 * Copyright 1995, Russell King
 */

#include <linux/delay.h>
#include <linux/types.h>
#include <linux/module.h>
#include <linux/ioport.h>
#include <linux/init.h>
#include <linux/blkdev.h>
#include <linux/interrupt.h>
#include <linux/platform_device.h>

#include <asm/hwtest.h>
#include <asm/io.h>
#include <asm/macintosh.h>
#include <asm/macints.h>
#include <asm/setup.h>

#include <scsi/scsi_host.h>

/* Definitions for the core NCR5380 driver. */

#define NCR5380_implementation_fields   int pdma_residual

#define NCR5380_read(reg)           in_8(hostdata->io + ((reg) << 4))
#define NCR5380_write(reg, value)   out_8(hostdata->io + ((reg) << 4), value)

#define NCR5380_dma_xfer_len            macscsi_dma_xfer_len
#define NCR5380_dma_recv_setup          macscsi_pread
#define NCR5380_dma_send_setup          macscsi_pwrite
#define NCR5380_dma_residual            macscsi_dma_residual

#define NCR5380_intr                    macscsi_intr
#define NCR5380_queue_command           macscsi_queue_command
#define NCR5380_abort                   macscsi_abort
#define NCR5380_host_reset              macscsi_host_reset
#define NCR5380_info                    macscsi_info

#include "NCR5380.h"

static int setup_can_queue = -1;
module_param(setup_can_queue, int, 0);
static int setup_cmd_per_lun = -1;
module_param(setup_cmd_per_lun, int, 0);
static int setup_sg_tablesize = -1;
module_param(setup_sg_tablesize, int, 0);
static int setup_use_pdma = 512;
module_param(setup_use_pdma, int, 0);
static int setup_hostid = -1;
module_param(setup_hostid, int, 0);
static int setup_toshiba_delay = -1;
module_param(setup_toshiba_delay, int, 0);

#ifndef MODULE
static int __init mac_scsi_setup(char *str)
{
        int ints[8];

        (void)get_options(str, ARRAY_SIZE(ints), ints);

        if (ints[0] < 1) {
                pr_err("Usage: mac5380=<can_queue>[,<cmd_per_lun>[,<sg_tablesize>[,<hostid>[,<use_tags>[,<use_pdma>[,<toshiba_delay>]]]]]]\n");
                return 0;
        }
        if (ints[0] >= 1)
                setup_can_queue = ints[1];
        if (ints[0] >= 2)
                setup_cmd_per_lun = ints[2];
        if (ints[0] >= 3)
                setup_sg_tablesize = ints[3];
        if (ints[0] >= 4)
                setup_hostid = ints[4];
        /* ints[5] (use_tagged_queuing) is ignored */
        if (ints[0] >= 6)
                setup_use_pdma = ints[6];
        if (ints[0] >= 7)
                setup_toshiba_delay = ints[7];
        return 1;
}

__setup("mac5380=", mac_scsi_setup);
#endif /* !MODULE */

/*
 * According to "Inside Macintosh: Devices", Mac OS requires disk drivers to
 * specify the number of bytes between the delays expected from a SCSI target.
 * This allows the operating system to "prevent bus errors when a target fails
 * to deliver the next byte within the processor bus error timeout period."
 * Linux SCSI drivers lack knowledge of the timing behaviour of SCSI targets
 * so bus errors are unavoidable.
 *
 * If a MOVE.B instruction faults during a receive operation, we assume the
 * target sent nothing and try again. That assumption probably depends on
 * target firmware but it seems to hold up okay. If a fault happens during a
 * send operation, the target may or may not have seen /ACK and got the byte.
 * It's uncertain so the whole SCSI command gets retried.
 *
 * The NOP is needed for synchronization because the fault address in the
 * exception stack frame may or may not be the instruction that actually
 * caused the bus error. Post-increment addressing can't be used.
 */

#define MOVE_BYTE(operands) \
        asm volatile ( \
                "1:     moveb " operands "     \n" \
                "11:    nop                    \n" \
                "       addq #1,%0             \n" \
                "       subq #1,%1             \n" \
                "40:                           \n" \
                "                              \n" \
                ".section .fixup,\"ax\"        \n" \
                ".even                         \n" \
                "90:    movel #1, %2           \n" \
                "       jra 40b                \n" \
                ".previous                     \n" \
                "                              \n" \
                ".section __ex_table,\"a\"     \n" \
                ".align  4                     \n" \
                ".long   1b,90b                \n" \
                ".long  11b,90b                \n" \
                ".previous                     \n" \
                : "+a" (addr), "+r" (n), "+r" (result) : "a" (io))

/*
 * If a MOVE.W (or MOVE.L) instruction faults, it cannot be retried because
 * the residual byte count would be uncertain. In that situation the MOVE_WORD
 * macro clears n in the fixup section to abort the transfer.
 */

#define MOVE_WORD(operands) \
        asm volatile ( \
                "1:     movew " operands "     \n" \
                "11:    nop                    \n" \
                "       subq #2,%1             \n" \
                "40:                           \n" \
                "                              \n" \
                ".section .fixup,\"ax\"        \n" \
                ".even                         \n" \
                "90:    movel #0, %1           \n" \
                "       movel #2, %2           \n" \
                "       jra 40b                \n" \
                ".previous                     \n" \
                "                              \n" \
                ".section __ex_table,\"a\"     \n" \
                ".align  4                     \n" \
                ".long   1b,90b                \n" \
                ".long  11b,90b                \n" \
                ".previous                     \n" \
                : "+a" (addr), "+r" (n), "+r" (result) : "a" (io))

#define MOVE_16_WORDS(operands) \
        asm volatile ( \
                "1:     movew " operands "     \n" \
                "2:     movew " operands "     \n" \
                "3:     movew " operands "     \n" \
                "4:     movew " operands "     \n" \
                "5:     movew " operands "     \n" \
                "6:     movew " operands "     \n" \
                "7:     movew " operands "     \n" \
                "8:     movew " operands "     \n" \
                "9:     movew " operands "     \n" \
                "10:    movew " operands "     \n" \
                "11:    movew " operands "     \n" \
                "12:    movew " operands "     \n" \
                "13:    movew " operands "     \n" \
                "14:    movew " operands "     \n" \
                "15:    movew " operands "     \n" \
                "16:    movew " operands "     \n" \
                "17:    nop                    \n" \
                "       subl  #32,%1           \n" \
                "40:                           \n" \
                "                              \n" \
                ".section .fixup,\"ax\"        \n" \
                ".even                         \n" \
                "90:    movel #0, %1           \n" \
                "       movel #2, %2           \n" \
                "       jra 40b                \n" \
                ".previous                     \n" \
                "                              \n" \
                ".section __ex_table,\"a\"     \n" \
                ".align  4                     \n" \
                ".long   1b,90b                \n" \
                ".long   2b,90b                \n" \
                ".long   3b,90b                \n" \
                ".long   4b,90b                \n" \
                ".long   5b,90b                \n" \
                ".long   6b,90b                \n" \
                ".long   7b,90b                \n" \
                ".long   8b,90b                \n" \
                ".long   9b,90b                \n" \
                ".long  10b,90b                \n" \
                ".long  11b,90b                \n" \
                ".long  12b,90b                \n" \
                ".long  13b,90b                \n" \
                ".long  14b,90b                \n" \
                ".long  15b,90b                \n" \
                ".long  16b,90b                \n" \
                ".long  17b,90b                \n" \
                ".previous                     \n" \
                : "+a" (addr), "+r" (n), "+r" (result) : "a" (io))

static inline int mac_pdma_recv(void __iomem *io, unsigned char *start, int n)
{
        unsigned char *addr = start;
        int result = 0;

        if (n >= 1) {
                MOVE_BYTE("%3@,%0@");
                if (result)
                        goto out;
        }
        if (n >= 1 && ((unsigned long)addr & 1)) {
                MOVE_BYTE("%3@,%0@");
                if (result)
                        goto out;
        }
        while (n >= 32)
                MOVE_16_WORDS("%3@,%0@+");
        while (n >= 2)
                MOVE_WORD("%3@,%0@+");
        if (result)
                return start - addr; /* Negated to indicate uncertain length */
        if (n == 1)
                MOVE_BYTE("%3@,%0@");
out:
        return addr - start;
}

static inline int mac_pdma_send(unsigned char *start, void __iomem *io, int n)
{
        unsigned char *addr = start;
        int result = 0;

        if (n >= 1) {
                MOVE_BYTE("%0@,%3@");
                if (result)
                        return -1;
        }
        if (n >= 1 && ((unsigned long)addr & 1)) {
                MOVE_BYTE("%0@,%3@");
                if (result)
                        return -2;
        }
        while (n >= 32)
                MOVE_16_WORDS("%0@+,%3@");
        while (n >= 2)
                MOVE_WORD("%0@+,%3@");
        if (result)
                return start - addr - 1; /* Negated to indicate uncertain length */
        if (n == 1)
                MOVE_BYTE("%0@,%3@");
        return addr - start;
}

/* The "SCSI DMA" chip on the IIfx implements this register. */
#define CTRL_REG                0x8
#define CTRL_INTERRUPTS_ENABLE  BIT(1)
#define CTRL_HANDSHAKE_MODE     BIT(3)

static inline void write_ctrl_reg(struct NCR5380_hostdata *hostdata, u32 value)
{
        out_be32(hostdata->io + (CTRL_REG << 4), value);
}

static inline int macscsi_wait_for_drq(struct NCR5380_hostdata *hostdata)
{
        unsigned int n = 1; /* effectively multiplies NCR5380_REG_POLL_TIME */
        unsigned char basr;

again:
        basr = NCR5380_read(BUS_AND_STATUS_REG);

        if (!(basr & BASR_PHASE_MATCH))
                return 1;

        if (basr & BASR_IRQ)
                return -1;

        if (basr & BASR_DRQ)
                return 0;

        if (n-- == 0) {
                NCR5380_dprint(NDEBUG_PSEUDO_DMA, hostdata->host);
                dsprintk(NDEBUG_PSEUDO_DMA, hostdata->host,
                         "%s: DRQ timeout\n", __func__);
                return -1;
        }

        NCR5380_poll_politely2(hostdata,
                               BUS_AND_STATUS_REG, BASR_DRQ, BASR_DRQ,
                               BUS_AND_STATUS_REG, BASR_PHASE_MATCH, 0, 0);
        goto again;
}

static inline int macscsi_pread(struct NCR5380_hostdata *hostdata,
                                unsigned char *dst, int len)
{
        u8 __iomem *s = hostdata->pdma_io + (INPUT_DATA_REG << 4);
        unsigned char *d = dst;

        hostdata->pdma_residual = len;

        while (macscsi_wait_for_drq(hostdata) == 0) {
                int bytes, chunk_bytes;

                if (macintosh_config->ident == MAC_MODEL_IIFX)
                        write_ctrl_reg(hostdata, CTRL_HANDSHAKE_MODE |
                                                 CTRL_INTERRUPTS_ENABLE);

                chunk_bytes = min(hostdata->pdma_residual, 512);
                bytes = mac_pdma_recv(s, d, chunk_bytes);

                if (macintosh_config->ident == MAC_MODEL_IIFX)
                        write_ctrl_reg(hostdata, CTRL_INTERRUPTS_ENABLE);

                if (bytes > 0) {
                        d += bytes;
                        hostdata->pdma_residual -= bytes;
                }

                if (hostdata->pdma_residual == 0)
                        break;

                if (bytes > 0)
                        continue;

                NCR5380_dprint(NDEBUG_PSEUDO_DMA, hostdata->host);
                dsprintk(NDEBUG_PSEUDO_DMA, hostdata->host,
                         "%s: bus error [%d/%d] (%d/%d)\n",
                         __func__, d - dst, len, bytes, chunk_bytes);

                if (bytes == 0)
                        continue;

                if (macscsi_wait_for_drq(hostdata) <= 0)
                        set_host_byte(hostdata->connected, DID_ERROR);
                break;
        }

        return 0;
}

static inline int macscsi_pwrite(struct NCR5380_hostdata *hostdata,
                                 unsigned char *src, int len)
{
        unsigned char *s = src;
        u8 __iomem *d = hostdata->pdma_io + (OUTPUT_DATA_REG << 4);

        hostdata->pdma_residual = len;

        while (macscsi_wait_for_drq(hostdata) == 0) {
                int bytes, chunk_bytes;

                if (macintosh_config->ident == MAC_MODEL_IIFX)
                        write_ctrl_reg(hostdata, CTRL_HANDSHAKE_MODE |
                                                 CTRL_INTERRUPTS_ENABLE);

                chunk_bytes = min(hostdata->pdma_residual, 512);
                bytes = mac_pdma_send(s, d, chunk_bytes);

                if (macintosh_config->ident == MAC_MODEL_IIFX)
                        write_ctrl_reg(hostdata, CTRL_INTERRUPTS_ENABLE);

                if (bytes > 0) {
                        s += bytes;
                        hostdata->pdma_residual -= bytes;
                }

                if (hostdata->pdma_residual == 0)
                        break;

                if (bytes > 0)
                        continue;

                NCR5380_dprint(NDEBUG_PSEUDO_DMA, hostdata->host);
                dsprintk(NDEBUG_PSEUDO_DMA, hostdata->host,
                         "%s: bus error [%d/%d] (%d/%d)\n",
                         __func__, s - src, len, bytes, chunk_bytes);

                if (bytes == 0)
                        continue;

                if (macscsi_wait_for_drq(hostdata) <= 0)
                        set_host_byte(hostdata->connected, DID_ERROR);
                break;
        }

        return 0;
}

static int macscsi_dma_xfer_len(struct NCR5380_hostdata *hostdata,
                                struct scsi_cmnd *cmd)
{
        int resid = NCR5380_to_ncmd(cmd)->this_residual;

        if (hostdata->flags & FLAG_NO_PSEUDO_DMA || resid < setup_use_pdma)
                return 0;

        return resid;
}

static int macscsi_dma_residual(struct NCR5380_hostdata *hostdata)
{
        return hostdata->pdma_residual;
}

#include "NCR5380.c"

#define DRV_MODULE_NAME         "mac_scsi"
#define PFX                     DRV_MODULE_NAME ": "

static struct scsi_host_template mac_scsi_template = {
        .module                 = THIS_MODULE,
        .proc_name              = DRV_MODULE_NAME,
        .name                   = "Macintosh NCR5380 SCSI",
        .info                   = macscsi_info,
        .queuecommand           = macscsi_queue_command,
        .eh_abort_handler       = macscsi_abort,
        .eh_host_reset_handler  = macscsi_host_reset,
        .can_queue              = 16,
        .this_id                = 7,
        .sg_tablesize           = SG_ALL,
        .cmd_per_lun            = 2,
        .dma_boundary           = PAGE_SIZE - 1,
        .cmd_size               = sizeof(struct NCR5380_cmd),
        .max_sectors            = 128,
};

static int __init mac_scsi_probe(struct platform_device *pdev)
{
        struct Scsi_Host *instance;
        struct NCR5380_hostdata *hostdata;
        int error;
        int host_flags = 0;
        struct resource *irq, *pio_mem, *pdma_mem = NULL;

        pio_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        if (!pio_mem)
                return -ENODEV;

        pdma_mem = platform_get_resource(pdev, IORESOURCE_MEM, 1);

        irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);

        if (!hwreg_present((unsigned char *)pio_mem->start +
                           (STATUS_REG << 4))) {
                pr_info(PFX "no device detected at %pap\n", &pio_mem->start);
                return -ENODEV;
        }

        if (setup_can_queue > 0)
                mac_scsi_template.can_queue = setup_can_queue;
        if (setup_cmd_per_lun > 0)
                mac_scsi_template.cmd_per_lun = setup_cmd_per_lun;
        if (setup_sg_tablesize > 0)
                mac_scsi_template.sg_tablesize = setup_sg_tablesize;
        if (setup_hostid >= 0)
                mac_scsi_template.this_id = setup_hostid & 7;

        if (macintosh_config->ident == MAC_MODEL_IIFX)
                mac_scsi_template.sg_tablesize = 1;

        instance = scsi_host_alloc(&mac_scsi_template,
                                   sizeof(struct NCR5380_hostdata));
        if (!instance)
                return -ENOMEM;

        if (irq)
                instance->irq = irq->start;
        else
                instance->irq = NO_IRQ;

        hostdata = shost_priv(instance);
        hostdata->base = pio_mem->start;
        hostdata->io = (u8 __iomem *)pio_mem->start;

        if (pdma_mem && setup_use_pdma)
                hostdata->pdma_io = (u8 __iomem *)pdma_mem->start;
        else
                host_flags |= FLAG_NO_PSEUDO_DMA;

        host_flags |= setup_toshiba_delay > 0 ? FLAG_TOSHIBA_DELAY : 0;

        if (instance->sg_tablesize > 1)
                host_flags |= FLAG_DMA_FIXUP;

        error = NCR5380_init(instance, host_flags | FLAG_LATE_DMA_SETUP);
        if (error)
                goto fail_init;

        if (instance->irq != NO_IRQ) {
                error = request_irq(instance->irq, macscsi_intr, IRQF_SHARED,
                                    "NCR5380", instance);
                if (error)
                        goto fail_irq;
        }

        NCR5380_maybe_reset_bus(instance);

        error = scsi_add_host(instance, NULL);
        if (error)
                goto fail_host;

        platform_set_drvdata(pdev, instance);

        scsi_scan_host(instance);
        return 0;

fail_host:
        if (instance->irq != NO_IRQ)
                free_irq(instance->irq, instance);
fail_irq:
        NCR5380_exit(instance);
fail_init:
        scsi_host_put(instance);
        return error;
}

static void __exit mac_scsi_remove(struct platform_device *pdev)
{
        struct Scsi_Host *instance = platform_get_drvdata(pdev);

        scsi_remove_host(instance);
        if (instance->irq != NO_IRQ)
                free_irq(instance->irq, instance);
        NCR5380_exit(instance);
        scsi_host_put(instance);
}

/*
 * mac_scsi_remove() lives in .exit.text. For drivers registered via
 * module_platform_driver_probe() this is ok because they cannot get unbound at
 * runtime. So mark the driver struct with __refdata to prevent modpost
 * triggering a section mismatch warning.
 */
static struct platform_driver mac_scsi_driver __refdata = {
        .remove = __exit_p(mac_scsi_remove),
        .driver = {
                .name   = DRV_MODULE_NAME,
        },
};

module_platform_driver_probe(mac_scsi_driver, mac_scsi_probe);

MODULE_ALIAS("platform:" DRV_MODULE_NAME);
MODULE_DESCRIPTION("Macintosh NCR5380 SCSI driver");
MODULE_LICENSE("GPL");