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cpcmd.c

/*
 *  arch/s390/kernel/cpcmd.c
 *
 *  S390 version
 *    Copyright IBM Corp. 1999,2007
 *    Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com),
 *               Christian Borntraeger (cborntra@de.ibm.com),
 */

#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/system.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) {
                  printk(KERN_WARNING
                        "cpcmd: could not allocate 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);

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