// SPDX-License-Identifier: GPL-2.0
/*
 * Author(s)......: Holger Smolinski <Holger.Smolinski@de.ibm.com>
 * Based on.......: linux/drivers/s390/block/mdisk.c
 * ...............: by Hartmunt Penner <hpenner@de.ibm.com>
 * Bugreports.to..: <Linux390@de.ibm.com>
 * Copyright IBM Corp. 1999, 2000
 *
 */

#include <linux/kernel_stat.h>
#include <linux/stddef.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/hdreg.h>
#include <linux/bio.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/jiffies.h>
#include <asm/asm-extable.h>
#include <asm/machine.h>
#include <asm/dasd.h>
#include <asm/debug.h>
#include <asm/diag.h>
#include <asm/ebcdic.h>
#include <linux/io.h>
#include <asm/irq.h>
#include <asm/vtoc.h>
#include <asm/asm.h>

#include "dasd_int.h"
#include "dasd_diag.h"

MODULE_DESCRIPTION("S/390 Support for DIAG access to DASD Disks");
MODULE_LICENSE("GPL");

/* The maximum number of blocks per request (max_blocks) is dependent on the
 * amount of storage that is available in the static I/O buffer for each
 * device. Currently each device gets 2 pages. We want to fit two requests
 * into the available memory so that we can immediately start the next if one
 * finishes. */
#define DIAG_MAX_BLOCKS (((2 * PAGE_SIZE - sizeof(struct dasd_ccw_req) - \
                           sizeof(struct dasd_diag_req)) / \
                           sizeof(struct dasd_diag_bio)) / 2)
#define DIAG_MAX_RETRIES        32
#define DIAG_TIMEOUT            50

static struct dasd_discipline dasd_diag_discipline;

struct dasd_diag_private {
        struct dasd_diag_characteristics rdc_data;
        struct dasd_diag_rw_io iob;
        struct dasd_diag_init_io iib;
        blocknum_t pt_block;
        struct ccw_dev_id dev_id;
};

struct dasd_diag_req {
        unsigned int block_count;
        struct dasd_diag_bio bio[];
};

static const u8 DASD_DIAG_CMS1[] = { 0xc3, 0xd4, 0xe2, 0xf1 };/* EBCDIC CMS1 */

/* Perform DIAG250 call with block I/O parameter list iob (input and output)
 * and function code cmd.
 * In case of an exception return 3. Otherwise return result of bitwise OR of
 * resulting condition code and DIAG return code. */
static inline int __dia250(void *iob, int cmd)
{
        union register_pair rx = { .even = (unsigned long)iob, };
        int cc, exception;
        typedef union {
                struct dasd_diag_init_io init_io;
                struct dasd_diag_rw_io rw_io;
        } addr_type;

        exception = 1;
        asm_inline volatile(
                "       diag    %[rx],%[cmd],0x250\n"
                "0:     lhi     %[exc],0\n"
                "1:\n"
                CC_IPM(cc)
                EX_TABLE(0b,1b)
                : CC_OUT(cc, cc), [rx] "+d" (rx.pair),
                  "+m" (*(addr_type *)iob), [exc] "+d" (exception)
                : [cmd] "d" (cmd)
                : CC_CLOBBER);
        cc = exception ? 3 : CC_TRANSFORM(cc);
        return cc | rx.odd;
}

static inline int dia250(void *iob, int cmd)
{
        diag_stat_inc(DIAG_STAT_X250);
        return __dia250(iob, cmd);
}

/* Initialize block I/O to DIAG device using the specified blocksize and
 * block offset. On success, return zero and set end_block to contain the
 * number of blocks on the device minus the specified offset. Return non-zero
 * otherwise. */
static inline int
mdsk_init_io(struct dasd_device *device, unsigned int blocksize,
             blocknum_t offset, blocknum_t *end_block)
{
        struct dasd_diag_private *private = device->private;
        struct dasd_diag_init_io *iib = &private->iib;
        int rc;

        memset(iib, 0, sizeof (struct dasd_diag_init_io));

        iib->dev_nr = private->dev_id.devno;
        iib->block_size = blocksize;
        iib->offset = offset;
        iib->flaga = DASD_DIAG_FLAGA_DEFAULT;

        rc = dia250(iib, INIT_BIO);

        if ((rc & 3) == 0 && end_block)
                *end_block = iib->end_block;

        return rc;
}

/* Remove block I/O environment for device. Return zero on success, non-zero
 * otherwise. */
static inline int
mdsk_term_io(struct dasd_device * device)
{
        struct dasd_diag_private *private = device->private;
        struct dasd_diag_init_io *iib = &private->iib;
        int rc;

        memset(iib, 0, sizeof (struct dasd_diag_init_io));
        iib->dev_nr = private->dev_id.devno;
        rc = dia250(iib, TERM_BIO);
        return rc;
}

/* Error recovery for failed DIAG requests - try to reestablish the DIAG
 * environment. */
static void
dasd_diag_erp(struct dasd_device *device)
{
        int rc;

        mdsk_term_io(device);
        rc = mdsk_init_io(device, device->block->bp_block, 0, NULL);
        if (rc == 4) {
                if (!(test_and_set_bit(DASD_FLAG_DEVICE_RO, &device->flags)))
                        pr_warn("%s: The access mode of a DIAG device changed to read-only\n",
                                dev_name(&device->cdev->dev));
                rc = 0;
        }
        if (rc)
                pr_warn("%s: DIAG ERP failed with rc=%d\n",
                        dev_name(&device->cdev->dev), rc);
}

/* Start a given request at the device. Return zero on success, non-zero
 * otherwise. */
static int
dasd_start_diag(struct dasd_ccw_req * cqr)
{
        struct dasd_device *device;
        struct dasd_diag_private *private;
        struct dasd_diag_req *dreq;
        int rc;

        device = cqr->startdev;
        if (cqr->retries < 0) {
                DBF_DEV_EVENT(DBF_ERR, device, "DIAG start_IO: request %p "
                            "- no retry left)", cqr);
                cqr->status = DASD_CQR_ERROR;
                return -EIO;
        }
        private = device->private;
        dreq = cqr->data;

        private->iob.dev_nr = private->dev_id.devno;
        private->iob.key = 0;
        private->iob.flags = DASD_DIAG_RWFLAG_ASYNC;
        private->iob.block_count = dreq->block_count;
        private->iob.interrupt_params = (addr_t) cqr;
        private->iob.bio_list = dreq->bio;
        private->iob.flaga = DASD_DIAG_FLAGA_DEFAULT;

        cqr->startclk = get_tod_clock();
        cqr->starttime = jiffies;
        cqr->retries--;

        rc = dia250(&private->iob, RW_BIO);
        switch (rc) {
        case 0: /* Synchronous I/O finished successfully */
                cqr->stopclk = get_tod_clock();
                cqr->status = DASD_CQR_SUCCESS;
                /* Indicate to calling function that only a dasd_schedule_bh()
                   and no timer is needed */
                rc = -EACCES;
                break;
        case 8: /* Asynchronous I/O was started */
                cqr->status = DASD_CQR_IN_IO;
                rc = 0;
                break;
        default: /* Error condition */
                cqr->status = DASD_CQR_QUEUED;
                DBF_DEV_EVENT(DBF_WARNING, device, "dia250 returned rc=%d", rc);
                dasd_diag_erp(device);
                rc = -EIO;
                break;
        }
        cqr->intrc = rc;
        return rc;
}

/* Terminate given request at the device. */
static int
dasd_diag_term_IO(struct dasd_ccw_req * cqr)
{
        struct dasd_device *device;

        device = cqr->startdev;
        mdsk_term_io(device);
        mdsk_init_io(device, device->block->bp_block, 0, NULL);
        cqr->status = DASD_CQR_CLEAR_PENDING;
        cqr->stopclk = get_tod_clock();
        dasd_schedule_device_bh(device);
        return 0;
}

/* Handle external interruption. */
static void dasd_ext_handler(struct ext_code ext_code,
                             unsigned int param32, unsigned long param64)
{
        struct dasd_ccw_req *cqr, *next;
        struct dasd_device *device;
        unsigned long expires;
        unsigned long flags;
        addr_t ip;
        int rc;

        switch (ext_code.subcode >> 8) {
        case DASD_DIAG_CODE_31BIT:
                ip = (addr_t) param32;
                break;
        case DASD_DIAG_CODE_64BIT:
                ip = (addr_t) param64;
                break;
        default:
                return;
        }
        inc_irq_stat(IRQEXT_DSD);
        if (!ip) {              /* no intparm: unsolicited interrupt */
                DBF_EVENT(DBF_NOTICE, "%s", "caught unsolicited "
                              "interrupt");
                return;
        }
        cqr = (struct dasd_ccw_req *) ip;
        device = (struct dasd_device *) cqr->startdev;
        if (strncmp(device->discipline->ebcname, (char *) &cqr->magic, 4)) {
                DBF_DEV_EVENT(DBF_WARNING, device,
                            " magic number of dasd_ccw_req 0x%08X doesn't"
                            " match discipline 0x%08X",
                            cqr->magic, *(int *) (&device->discipline->name));
                return;
        }

        /* get irq lock to modify request queue */
        spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);

        /* Check for a pending clear operation */
        if (cqr->status == DASD_CQR_CLEAR_PENDING) {
                cqr->status = DASD_CQR_CLEARED;
                dasd_device_clear_timer(device);
                dasd_schedule_device_bh(device);
                spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
                return;
        }

        cqr->stopclk = get_tod_clock();

        expires = 0;
        if ((ext_code.subcode & 0xff) == 0) {
                cqr->status = DASD_CQR_SUCCESS;
                /* Start first request on queue if possible -> fast_io. */
                if (!list_empty(&device->ccw_queue)) {
                        next = list_entry(device->ccw_queue.next,
                                          struct dasd_ccw_req, devlist);
                        if (next->status == DASD_CQR_QUEUED) {
                                rc = dasd_start_diag(next);
                                if (rc == 0)
                                        expires = next->expires;
                        }
                }
        } else {
                cqr->status = DASD_CQR_QUEUED;
                DBF_DEV_EVENT(DBF_DEBUG, device, "interrupt status for "
                              "request %p was %d (%d retries left)", cqr,
                              ext_code.subcode & 0xff, cqr->retries);
                dasd_diag_erp(device);
        }

        if (expires != 0)
                dasd_device_set_timer(device, expires);
        else
                dasd_device_clear_timer(device);
        dasd_schedule_device_bh(device);

        spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
}

/* Check whether device can be controlled by DIAG discipline. Return zero on
 * success, non-zero otherwise. */
static int
dasd_diag_check_device(struct dasd_device *device)
{
        struct dasd_diag_private *private = device->private;
        struct dasd_diag_characteristics *rdc_data;
        struct vtoc_cms_label *label;
        struct dasd_block *block;
        struct dasd_diag_bio *bio;
        unsigned int sb, bsize;
        blocknum_t end_block;
        int rc;

        if (private == NULL) {
                private = kzalloc_obj(*private);
                if (private == NULL) {
                        DBF_DEV_EVENT(DBF_WARNING, device, "%s",
                                "Allocating memory for private DASD data "
                                      "failed\n");
                        return -ENOMEM;
                }
                ccw_device_get_id(device->cdev, &private->dev_id);
                device->private = private;
        }
        block = dasd_alloc_block();
        if (IS_ERR(block)) {
                DBF_DEV_EVENT(DBF_WARNING, device, "%s",
                            "could not allocate dasd block structure");
                device->private = NULL;
                kfree(private);
                return PTR_ERR(block);
        }
        device->block = block;
        block->base = device;

        /* Read Device Characteristics */
        rdc_data = &private->rdc_data;
        rdc_data->dev_nr = private->dev_id.devno;
        rdc_data->rdc_len = sizeof (struct dasd_diag_characteristics);

        rc = diag210((struct diag210 *) rdc_data);
        if (rc) {
                DBF_DEV_EVENT(DBF_WARNING, device, "failed to retrieve device "
                            "information (rc=%d)", rc);
                rc = -EOPNOTSUPP;
                goto out;
        }

        device->default_expires = DIAG_TIMEOUT;
        device->default_retries = DIAG_MAX_RETRIES;

        /* Figure out position of label block */
        switch (private->rdc_data.vdev_class) {
        case DEV_CLASS_FBA:
                private->pt_block = 1;
                break;
        case DEV_CLASS_ECKD:
                private->pt_block = 2;
                break;
        default:
                pr_warn("%s: Device type %d is not supported in DIAG mode\n",
                        dev_name(&device->cdev->dev),
                        private->rdc_data.vdev_class);
                rc = -EOPNOTSUPP;
                goto out;
        }

        DBF_DEV_EVENT(DBF_INFO, device,
                      "%04X: %04X on real %04X/%02X",
                      rdc_data->dev_nr,
                      rdc_data->vdev_type,
                      rdc_data->rdev_type, rdc_data->rdev_model);

        /* terminate all outstanding operations */
        mdsk_term_io(device);

        /* figure out blocksize of device */
        label = (struct vtoc_cms_label *) get_zeroed_page(GFP_KERNEL);
        if (label == NULL)  {
                DBF_DEV_EVENT(DBF_WARNING, device, "%s",
                            "No memory to allocate initialization request");
                rc = -ENOMEM;
                goto out;
        }
        bio = kzalloc_obj(*bio);
        if (bio == NULL)  {
                DBF_DEV_EVENT(DBF_WARNING, device, "%s",
                              "No memory to allocate initialization bio");
                rc = -ENOMEM;
                goto out_label;
        }
        rc = 0;
        end_block = 0;
        /* try all sizes - needed for ECKD devices */
        for (bsize = 512; bsize <= PAGE_SIZE; bsize <<= 1) {
                mdsk_init_io(device, bsize, 0, &end_block);
                memset(bio, 0, sizeof(*bio));
                bio->type = MDSK_READ_REQ;
                bio->block_number = private->pt_block + 1;
                bio->buffer = label;
                memset(&private->iob, 0, sizeof (struct dasd_diag_rw_io));
                private->iob.dev_nr = rdc_data->dev_nr;
                private->iob.key = 0;
                private->iob.flags = 0; /* do synchronous io */
                private->iob.block_count = 1;
                private->iob.interrupt_params = 0;
                private->iob.bio_list = bio;
                private->iob.flaga = DASD_DIAG_FLAGA_DEFAULT;
                rc = dia250(&private->iob, RW_BIO);
                if (rc == 3) {
                        pr_warn("%s: A 64-bit DIAG call failed\n",
                                dev_name(&device->cdev->dev));
                        rc = -EOPNOTSUPP;
                        goto out_bio;
                }
                mdsk_term_io(device);
                if (rc == 0)
                        break;
        }
        if (bsize > PAGE_SIZE) {
                pr_warn("%s: Accessing the DASD failed because of an incorrect format (rc=%d)\n",
                        dev_name(&device->cdev->dev), rc);
                rc = -EIO;
                goto out_bio;
        }
        /* check for label block */
        if (memcmp(label->label_id, DASD_DIAG_CMS1,
                  sizeof(DASD_DIAG_CMS1)) == 0) {
                /* get formatted blocksize from label block */
                bsize = (unsigned int) label->block_size;
                block->blocks = (unsigned long) label->block_count;
        } else
                block->blocks = end_block;
        block->bp_block = bsize;
        block->s2b_shift = 0;   /* bits to shift 512 to get a block */
        for (sb = 512; sb < bsize; sb = sb << 1)
                block->s2b_shift++;
        rc = mdsk_init_io(device, block->bp_block, 0, NULL);
        if (rc && (rc != 4)) {
                pr_warn("%s: DIAG initialization failed with rc=%d\n",
                        dev_name(&device->cdev->dev), rc);
                rc = -EIO;
        } else {
                if (rc == 4)
                        set_bit(DASD_FLAG_DEVICE_RO, &device->flags);
                pr_info("%s: New DASD with %ld byte/block, total size %ld "
                        "KB%s\n", dev_name(&device->cdev->dev),
                        (unsigned long) block->bp_block,
                        (unsigned long) (block->blocks <<
                                         block->s2b_shift) >> 1,
                        (rc == 4) ? ", read-only device" : "");
                rc = 0;
        }
out_bio:
        kfree(bio);
out_label:
        free_page((long) label);
out:
        if (rc) {
                device->block = NULL;
                dasd_free_block(block);
                device->private = NULL;
                kfree(private);
        }
        return rc;
}

/* Fill in virtual disk geometry for device. Return zero on success, non-zero
 * otherwise. */
static int
dasd_diag_fill_geometry(struct dasd_block *block, struct hd_geometry *geo)
{
        if (dasd_check_blocksize(block->bp_block) != 0)
                return -EINVAL;
        geo->cylinders = (block->blocks << block->s2b_shift) >> 10;
        geo->heads = 16;
        geo->sectors = 128 >> block->s2b_shift;
        return 0;
}

static dasd_erp_fn_t
dasd_diag_erp_action(struct dasd_ccw_req * cqr)
{
        return dasd_default_erp_action;
}

static dasd_erp_fn_t
dasd_diag_erp_postaction(struct dasd_ccw_req * cqr)
{
        return dasd_default_erp_postaction;
}

/* Create DASD request from block device request. Return pointer to new
 * request on success, ERR_PTR otherwise. */
static struct dasd_ccw_req *dasd_diag_build_cp(struct dasd_device *memdev,
                                               struct dasd_block *block,
                                               struct request *req)
{
        struct dasd_ccw_req *cqr;
        struct dasd_diag_req *dreq;
        struct dasd_diag_bio *dbio;
        struct req_iterator iter;
        struct bio_vec bv;
        char *dst;
        unsigned int count;
        sector_t recid, first_rec, last_rec;
        unsigned int blksize, off;
        unsigned char rw_cmd;

        if (rq_data_dir(req) == READ)
                rw_cmd = MDSK_READ_REQ;
        else if (rq_data_dir(req) == WRITE)
                rw_cmd = MDSK_WRITE_REQ;
        else
                return ERR_PTR(-EINVAL);
        blksize = block->bp_block;
        /* Calculate record id of first and last block. */
        first_rec = blk_rq_pos(req) >> block->s2b_shift;
        last_rec =
                (blk_rq_pos(req) + blk_rq_sectors(req) - 1) >> block->s2b_shift;
        /* Check struct bio and count the number of blocks for the request. */
        count = 0;
        rq_for_each_segment(bv, req, iter) {
                if (bv.bv_len & (blksize - 1))
                        /* Fba can only do full blocks. */
                        return ERR_PTR(-EINVAL);
                count += bv.bv_len >> (block->s2b_shift + 9);
        }
        /* Paranoia. */
        if (count != last_rec - first_rec + 1)
                return ERR_PTR(-EINVAL);
        /* Build the request */
        cqr = dasd_smalloc_request(DASD_DIAG_MAGIC, 0, struct_size(dreq, bio, count),
                                   memdev, blk_mq_rq_to_pdu(req));
        if (IS_ERR(cqr))
                return cqr;

        dreq = (struct dasd_diag_req *) cqr->data;
        dreq->block_count = count;
        dbio = dreq->bio;
        recid = first_rec;
        rq_for_each_segment(bv, req, iter) {
                dst = bvec_virt(&bv);
                for (off = 0; off < bv.bv_len; off += blksize) {
                        memset(dbio, 0, sizeof (struct dasd_diag_bio));
                        dbio->type = rw_cmd;
                        dbio->block_number = recid + 1;
                        dbio->buffer = dst;
                        dbio++;
                        dst += blksize;
                        recid++;
                }
        }
        cqr->retries = memdev->default_retries;
        cqr->buildclk = get_tod_clock();
        if (blk_noretry_request(req) ||
            block->base->features & DASD_FEATURE_FAILFAST)
                set_bit(DASD_CQR_FLAGS_FAILFAST, &cqr->flags);
        cqr->startdev = memdev;
        cqr->memdev = memdev;
        cqr->block = block;
        cqr->expires = memdev->default_expires * HZ;
        cqr->status = DASD_CQR_FILLED;
        return cqr;
}

/* Release DASD request. Return non-zero if request was successful, zero
 * otherwise. */
static int
dasd_diag_free_cp(struct dasd_ccw_req *cqr, struct request *req)
{
        int status;

        status = cqr->status == DASD_CQR_DONE;
        dasd_sfree_request(cqr, cqr->memdev);
        return status;
}

static void dasd_diag_handle_terminated_request(struct dasd_ccw_req *cqr)
{
        if (cqr->retries < 0)
                cqr->status = DASD_CQR_FAILED;
        else
                cqr->status = DASD_CQR_FILLED;
};

/* Fill in IOCTL data for device. */
static int
dasd_diag_fill_info(struct dasd_device * device,
                    struct dasd_information2_t * info)
{
        struct dasd_diag_private *private = device->private;

        info->label_block = (unsigned int) private->pt_block;
        info->FBA_layout = 1;
        info->format = DASD_FORMAT_LDL;
        info->characteristics_size = sizeof(private->rdc_data);
        memcpy(info->characteristics, &private->rdc_data,
               sizeof(private->rdc_data));
        info->confdata_size = 0;
        return 0;
}

static void
dasd_diag_dump_sense(struct dasd_device *device, struct dasd_ccw_req * req,
                     struct irb *stat)
{
        DBF_DEV_EVENT(DBF_WARNING, device, "%s",
                    "dump sense not available for DIAG data");
}

static unsigned int dasd_diag_max_sectors(struct dasd_block *block)
{
        return DIAG_MAX_BLOCKS << block->s2b_shift;
}

static int dasd_diag_pe_handler(struct dasd_device *device,
                                __u8 tbvpm, __u8 fcsecpm)
{
        return dasd_generic_verify_path(device, tbvpm);
}

static struct dasd_discipline dasd_diag_discipline = {
        .owner = THIS_MODULE,
        .name = "DIAG",
        .ebcname = "DIAG",
        .max_sectors = dasd_diag_max_sectors,
        .check_device = dasd_diag_check_device,
        .pe_handler = dasd_diag_pe_handler,
        .fill_geometry = dasd_diag_fill_geometry,
        .start_IO = dasd_start_diag,
        .term_IO = dasd_diag_term_IO,
        .handle_terminated_request = dasd_diag_handle_terminated_request,
        .erp_action = dasd_diag_erp_action,
        .erp_postaction = dasd_diag_erp_postaction,
        .build_cp = dasd_diag_build_cp,
        .free_cp = dasd_diag_free_cp,
        .dump_sense = dasd_diag_dump_sense,
        .fill_info = dasd_diag_fill_info,
};

static int __init
dasd_diag_init(void)
{
        if (!machine_is_vm()) {
                pr_info("Discipline %s cannot be used without z/VM\n",
                        dasd_diag_discipline.name);
                return -ENODEV;
        }
        ASCEBC(dasd_diag_discipline.ebcname, 4);

        irq_subclass_register(IRQ_SUBCLASS_SERVICE_SIGNAL);
        register_external_irq(EXT_IRQ_CP_SERVICE, dasd_ext_handler);
        dasd_diag_discipline_pointer = &dasd_diag_discipline;
        return 0;
}

static void __exit
dasd_diag_cleanup(void)
{
        unregister_external_irq(EXT_IRQ_CP_SERVICE, dasd_ext_handler);
        irq_subclass_unregister(IRQ_SUBCLASS_SERVICE_SIGNAL);
        dasd_diag_discipline_pointer = NULL;
}

module_init(dasd_diag_init);
module_exit(dasd_diag_cleanup);