arch/s390/kernel/cpcmd.c

   1 /*
   2  *  S390 version
   3  *    Copyright IBM Corp. 1999, 2007
   4  *    Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com),
   5  *               Christian Borntraeger (cborntra@de.ibm.com),
   6  */
   7
   8 #define KMSG_COMPONENT "cpcmd"
   9 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
  10
  11 #include <linux/kernel.h>
  12 #include <linux/module.h>
  13 #include <linux/slab.h>
  14 #include <linux/spinlock.h>
  15 #include <linux/stddef.h>
  16 #include <linux/string.h>
  17 #include <asm/ebcdic.h>
  18 #include <asm/cpcmd.h>
  19 #include <asm/io.h>
  20
  21 static DEFINE_SPINLOCK(cpcmd_lock);
  22 static char cpcmd_buf[241];
  23
  24 static int diag8_noresponse(int cmdlen)
  25 {
  26         register unsigned long reg2 asm ("2") = (addr_t) cpcmd_buf;
  27         register unsigned long reg3 asm ("3") = cmdlen;
  28
  29         asm volatile(
  30                 "       sam31\n"
  31                 "       diag    %1,%0,0x8\n"
  32                 "       sam64\n"
  33                 : "+d" (reg3) : "d" (reg2) : "cc");
  34         return reg3;
  35 }
  36
  37 static int diag8_response(int cmdlen, char *response, int *rlen)
  38 {
  39         register unsigned long reg2 asm ("2") = (addr_t) cpcmd_buf;
  40         register unsigned long reg3 asm ("3") = (addr_t) response;
  41         register unsigned long reg4 asm ("4") = cmdlen | 0x40000000L;
  42         register unsigned long reg5 asm ("5") = *rlen;
  43
  44         asm volatile(
  45                 "       sam31\n"
  46                 "       diag    %2,%0,0x8\n"
  47                 "       sam64\n"
  48                 "       brc     8,1f\n"
  49                 "       agr     %1,%4\n"
  50                 "1:\n"
  51                 : "+d" (reg4), "+d" (reg5)
  52                 : "d" (reg2), "d" (reg3), "d" (*rlen) : "cc");
  53         *rlen = reg5;
  54         return reg4;
  55 }
  56
  57 /*
  58  * __cpcmd has some restrictions over cpcmd
  59  *  - the response buffer must reside below 2GB (if any)
  60  *  - __cpcmd is unlocked and therefore not SMP-safe
  61  */
  62 int  __cpcmd(const char *cmd, char *response, int rlen, int *response_code)
  63 {
  64         int cmdlen;
  65         int rc;
  66         int response_len;
  67
  68         cmdlen = strlen(cmd);
  69         BUG_ON(cmdlen > 240);
  70         memcpy(cpcmd_buf, cmd, cmdlen);
  71         ASCEBC(cpcmd_buf, cmdlen);
  72
  73         if (response) {
  74                 memset(response, 0, rlen);
  75                 response_len = rlen;
  76                 rc = diag8_response(cmdlen, response, &rlen);
  77                 EBCASC(response, response_len);
  78         } else {
  79                 rc = diag8_noresponse(cmdlen);
  80         }
  81         if (response_code)
  82                 *response_code = rc;
  83         return rlen;
  84 }
  85 EXPORT_SYMBOL(__cpcmd);
  86
  87 int cpcmd(const char *cmd, char *response, int rlen, int *response_code)
  88 {
  89         char *lowbuf;
  90         int len;
  91         unsigned long flags;
  92
  93         if ((virt_to_phys(response) != (unsigned long) response) ||
  94                         (((unsigned long)response + rlen) >> 31)) {
  95                 lowbuf = kmalloc(rlen, GFP_KERNEL | GFP_DMA);
  96                 if (!lowbuf) {
  97                         pr_warning("The cpcmd kernel function failed to "
  98                                    "allocate a response buffer\n");
  99                         return -ENOMEM;
 100                 }
 101                 spin_lock_irqsave(&cpcmd_lock, flags);
 102                 len = __cpcmd(cmd, lowbuf, rlen, response_code);
 103                 spin_unlock_irqrestore(&cpcmd_lock, flags);
 104                 memcpy(response, lowbuf, rlen);
 105                 kfree(lowbuf);
 106         } else {
 107                 spin_lock_irqsave(&cpcmd_lock, flags);
 108                 len = __cpcmd(cmd, response, rlen, response_code);
 109                 spin_unlock_irqrestore(&cpcmd_lock, flags);
 110         }
 111         return len;
 112 }
 113 EXPORT_SYMBOL(cpcmd);