qemu-e2k/pc-bios/s390-ccw/cio.c

/*
 * S390 Channel I/O
 *
 * Copyright (c) 2013 Alexander Graf <agraf@suse.de>
 * Copyright (c) 2019 IBM Corp.
 *
 * Author(s): Jason J. Herne <jjherne@us.ibm.com>
 *
 * This work is licensed under the terms of the GNU GPL, version 2 or (at
 * your option) any later version. See the COPYING file in the top-level
 * directory.
 */

#include "libc.h"
#include "s390-ccw.h"
#include "s390-arch.h"
#include "helper.h"
#include "cio.h"

static char chsc_page[PAGE_SIZE] __attribute__((__aligned__(PAGE_SIZE)));

static int __do_cio(SubChannelId schid, uint32_t ccw_addr, int fmt, Irb *irb);

int enable_mss_facility(void)
{
    int ret;
    ChscAreaSda *sda_area = (ChscAreaSda *) chsc_page;

    memset(sda_area, 0, PAGE_SIZE);
    sda_area->request.length = 0x0400;
    sda_area->request.code = 0x0031;
    sda_area->operation_code = 0x2;

    ret = chsc(sda_area);
    if ((ret == 0) && (sda_area->response.code == 0x0001)) {
        return 0;
    }
    return -EIO;
}

void enable_subchannel(SubChannelId schid)
{
    Schib schib;

    stsch_err(schid, &schib);
    schib.pmcw.ena = 1;
    msch(schid, &schib);
}

uint16_t cu_type(SubChannelId schid)
{
    Ccw1 sense_id_ccw;
    SenseId sense_data;

    sense_id_ccw.cmd_code = CCW_CMD_SENSE_ID;
    sense_id_ccw.cda = ptr2u32(&sense_data);
    sense_id_ccw.count = sizeof(sense_data);
    sense_id_ccw.flags |= CCW_FLAG_SLI;

    if (do_cio(schid, CU_TYPE_UNKNOWN, ptr2u32(&sense_id_ccw), CCW_FMT1)) {
        panic("Failed to run SenseID CCw\n");
    }

    return sense_data.cu_type;
}

int basic_sense(SubChannelId schid, uint16_t cutype, void *sense_data,
                 uint16_t data_size)
{
    Ccw1 senseCcw;
    Irb irb;

    senseCcw.cmd_code = CCW_CMD_BASIC_SENSE;
    senseCcw.cda = ptr2u32(sense_data);
    senseCcw.count = data_size;

    return __do_cio(schid, ptr2u32(&senseCcw), CCW_FMT1, &irb);
}

static bool irb_error(Irb *irb)
{
    if (irb->scsw.cstat) {
        return true;
    }
    return irb->scsw.dstat != (SCSW_DSTAT_DEVEND | SCSW_DSTAT_CHEND);
}

/*
 * Handles executing ssch, tsch and returns the irb obtained from tsch.
 * Returns 0 on success, -1 if unexpected status pending and we need to retry,
 * otherwise returns condition code from ssch/tsch for error cases.
 */
static int __do_cio(SubChannelId schid, uint32_t ccw_addr, int fmt, Irb *irb)
{
    CmdOrb orb = {};
    int rc;

    IPL_assert(fmt == 0 || fmt == 1, "Invalid ccw format");

    /* ccw_addr must be <= 24 bits and point to at least one whole ccw. */
    if (fmt == 0) {
        IPL_assert(ccw_addr <= 0xFFFFFF - 8, "Invalid ccw address");
    }

    orb.fmt = fmt;
    orb.pfch = 1;  /* QEMU's cio implementation requires prefetch */
    orb.c64 = 1;   /* QEMU's cio implementation requires 64-bit idaws */
    orb.lpm = 0xFF; /* All paths allowed */
    orb.cpa = ccw_addr;

    rc = ssch(schid, &orb);
    if (rc == 1 || rc == 2) {
        /* Subchannel status pending or busy. Eat status and ask for retry. */
        tsch(schid, irb);
        return -1;
    }
    if (rc) {
        print_int("ssch failed with cc=", rc);
        return rc;
    }

    consume_io_int();

    /* collect status */
    rc = tsch(schid, irb);
    if (rc) {
        print_int("tsch failed with cc=", rc);
    }

    return rc;
}

/*
 * Executes a channel program at a given subchannel. The request to run the
 * channel program is sent to the subchannel, we then wait for the interrupt
 * signaling completion of the I/O operation(s) performed by the channel
 * program. Lastly we verify that the i/o operation completed without error and
 * that the interrupt we received was for the subchannel used to run the
 * channel program.
 *
 * Note: This function assumes it is running in an environment where no other
 * cpus are generating or receiving I/O interrupts. So either run it in a
 * single-cpu environment or make sure all other cpus are not doing I/O and
 * have I/O interrupts masked off. We also assume that only one device is
 * active (generating i/o interrupts).
 *
 * Returns non-zero on error.
 */
int do_cio(SubChannelId schid, uint16_t cutype, uint32_t ccw_addr, int fmt)
{
    Irb irb = {};
    SenseDataEckdDasd sd;
    int rc, retries = 0;

    while (true) {
        rc = __do_cio(schid, ccw_addr, fmt, &irb);

        if (rc == -1) {
            retries++;
            continue;
        }
        if (rc) {
            /* ssch/tsch error. Message already reported by __do_cio */
            break;
        }

        if (!irb_error(&irb)) {
            break;
        }

        /*
         * Unexpected unit check, or interface-control-check. Use sense to
         * clear (unit check only) then retry.
         */
        if ((unit_check(&irb) || iface_ctrl_check(&irb)) && retries <= 2) {
            if (unit_check(&irb)) {
                basic_sense(schid, cutype, &sd, sizeof(sd));
            }
            retries++;
            continue;
        }

        rc = -1;
        break;
    }

    return rc;
}