cpcmd.c

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/*
 *  S390 version
 *    Copyright IBM Corp. 1999, 2007
 *    Author(s): Martin Schwidefsky ([email protected]),
 *               Christian Borntraeger ([email protected]),
 */

#define KMSG_COMPONENT "cpcmd"
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt

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

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

static int diag8_noresponse(int cmdlen)
{
    register unsigned long reg2 asm ("2") = (addr_t) cpcmd_buf;
    register unsigned long reg3 asm ("3") = cmdlen;

    asm volatile(
#ifndef CONFIG_64BIT
        "   diag    %1,%0,0x8\n"
#else /* CONFIG_64BIT */
        "   sam31\n"
        "   diag    %1,%0,0x8\n"
        "   sam64\n"
#endif /* CONFIG_64BIT */
        : "+d" (reg3) : "d" (reg2) : "cc");
    return reg3;
}

static int diag8_response(int cmdlen, char *response, int *rlen)
{
    register unsigned long reg2 asm ("2") = (addr_t) cpcmd_buf;
    register unsigned long reg3 asm ("3") = (addr_t) response;
    register unsigned long reg4 asm ("4") = cmdlen | 0x40000000L;
    register unsigned long reg5 asm ("5") = *rlen;

    asm volatile(
#ifndef CONFIG_64BIT
        "   diag    %2,%0,0x8\n"
        "   brc 8,1f\n"
        "   ar  %1,%4\n"
#else /* CONFIG_64BIT */
        "   sam31\n"
        "   diag    %2,%0,0x8\n"
        "   sam64\n"
        "   brc 8,1f\n"
        "   agr %1,%4\n"
#endif /* CONFIG_64BIT */
        "1:\n"
        : "+d" (reg4), "+d" (reg5)
        : "d" (reg2), "d" (reg3), "d" (*rlen) : "cc");
    *rlen = reg5;
    return reg4;
}

/*
 * __cpcmd has some restrictions over cpcmd
 *  - the response buffer must reside below 2GB (if any)
 *  - __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);

    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)
{
    char *lowbuf;
    int len;
    unsigned long flags;

    if ((virt_to_phys(response) != (unsigned long) response) ||
            (((unsigned long)response + rlen) >> 31)) {
        lowbuf = kmalloc(rlen, GFP_KERNEL | GFP_DMA);
        if (!lowbuf) {
            pr_warning("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);