// SPDX-License-Identifier: GPL-2.0
/*
 *  S390 version
 *    Copyright IBM Corp. 1999, 2007
 *    Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com),
 *               Christian Borntraeger (cborntra@de.ibm.com),
 */

#define pr_fmt(fmt) "cpcmd: " fmt

#include <linux/kernel.h>
#include <linux/export.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/stddef.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/io.h>
#include <asm/diag.h>
#include <asm/ebcdic.h>
#include <asm/cpcmd.h>
#include <asm/asm.h>

static DEFINE_SPINLOCK(cpcmd_lock);
static char cpcmd_buf[241];

static int diag8_noresponse(int cmdlen)
{
        asm volatile(
                "       diag    %[rx],%[ry],0x8\n"
                : [ry] "+&d" (cmdlen)
                : [rx] "d" (__pa(cpcmd_buf))
                : "cc");
        return cmdlen;
}

static int diag8_response(int cmdlen, char *response, int *rlen)
{
        union register_pair rx, ry;
        int cc;

        rx.even = __pa(cpcmd_buf);
        rx.odd  = __pa(response);
        ry.even = cmdlen | 0x40000000L;
        ry.odd  = *rlen;
        asm volatile(
                "       diag    %[rx],%[ry],0x8\n"
                CC_IPM(cc)
                : CC_OUT(cc, cc), [ry] "+d" (ry.pair)
                : [rx] "d" (rx.pair)
                : CC_CLOBBER);
        if (CC_TRANSFORM(cc))
                *rlen += ry.odd;
        else
                *rlen = ry.odd;
        return ry.even;
}

/*
 * __cpcmd has some restrictions over cpcmd
 *  - __cpcmd is unlocked and therefore not SMP-safe
 */
int  __cpcmd(const char *cmd, char *response, int rlen, int *response_code)
{
        int cmdlen;
        int rc;
        int response_len;

        cmdlen = strlen(cmd);
        BUG_ON(cmdlen > 240);
        memcpy(cpcmd_buf, cmd, cmdlen);
        ASCEBC(cpcmd_buf, cmdlen);

        diag_stat_inc(DIAG_STAT_X008);
        if (response) {
                memset(response, 0, rlen);
                response_len = rlen;
                rc = diag8_response(cmdlen, response, &rlen);
                EBCASC(response, response_len);
        } else {
                rc = diag8_noresponse(cmdlen);
        }
        if (response_code)
                *response_code = rc;
        return rlen;
}
EXPORT_SYMBOL(__cpcmd);

int cpcmd(const char *cmd, char *response, int rlen, int *response_code)
{
        unsigned long flags;
        char *lowbuf;
        int len;

        if (is_vmalloc_or_module_addr(response)) {
                lowbuf = kmalloc(rlen, GFP_KERNEL);
                if (!lowbuf) {
                        pr_warn("The cpcmd kernel function failed to allocate a response buffer\n");
                        return -ENOMEM;
                }
                spin_lock_irqsave(&cpcmd_lock, flags);
                len = __cpcmd(cmd, lowbuf, rlen, response_code);
                spin_unlock_irqrestore(&cpcmd_lock, flags);
                memcpy(response, lowbuf, rlen);
                kfree(lowbuf);
        } else {
                spin_lock_irqsave(&cpcmd_lock, flags);
                len = __cpcmd(cmd, response, rlen, response_code);
                spin_unlock_irqrestore(&cpcmd_lock, flags);
        }
        return len;
}
EXPORT_SYMBOL(cpcmd);