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 #ifndef CONFIG_64BIT
  31                 "       diag    %1,%0,0x8\n"
  32 #else /* CONFIG_64BIT */
  33                 "       sam31\n"
  34                 "       diag    %1,%0,0x8\n"
  35                 "       sam64\n"
  36 #endif /* CONFIG_64BIT */
  37                 : "+d" (reg3) : "d" (reg2) : "cc");
  38         return reg3;
  39 }
  40
  41 static int diag8_response(int cmdlen, char *response, int *rlen)
  42 {
  43         register unsigned long reg2 asm ("2") = (addr_t) cpcmd_buf;
  44         register unsigned long reg3 asm ("3") = (addr_t) response;
  45         register unsigned long reg4 asm ("4") = cmdlen | 0x40000000L;
  46         register unsigned long reg5 asm ("5") = *rlen;
  47
  48         asm volatile(
  49 #ifndef CONFIG_64BIT
  50                 "       diag    %2,%0,0x8\n"
  51                 "       brc     8,1f\n"
  52                 "       ar      %1,%4\n"
  53 #else /* CONFIG_64BIT */
  54                 "       sam31\n"
  55                 "       diag    %2,%0,0x8\n"
  56                 "       sam64\n"
  57                 "       brc     8,1f\n"
  58                 "       agr     %1,%4\n"
  59 #endif /* CONFIG_64BIT */
  60                 "1:\n"
  61                 : "+d" (reg4), "+d" (reg5)
  62                 : "d" (reg2), "d" (reg3), "d" (*rlen) : "cc");
  63         *rlen = reg5;
  64         return reg4;
  65 }
  66
  67 /*
  68  * __cpcmd has some restrictions over cpcmd
  69  *  - the response buffer must reside below 2GB (if any)
  70  *  - __cpcmd is unlocked and therefore not SMP-safe
  71  */
  72 int  __cpcmd(const char *cmd, char *response, int rlen, int *response_code)
  73 {
  74         int cmdlen;
  75         int rc;
  76         int response_len;
  77
  78         cmdlen = strlen(cmd);
  79         BUG_ON(cmdlen > 240);
  80         memcpy(cpcmd_buf, cmd, cmdlen);
  81         ASCEBC(cpcmd_buf, cmdlen);
  82
  83         if (response) {
  84                 memset(response, 0, rlen);
  85                 response_len = rlen;
  86                 rc = diag8_response(cmdlen, response, &rlen);
  87                 EBCASC(response, response_len);
  88         } else {
  89                 rc = diag8_noresponse(cmdlen);
  90         }
  91         if (response_code)
  92                 *response_code = rc;
  93         return rlen;
  94 }
  95 EXPORT_SYMBOL(__cpcmd);
  96
  97 int cpcmd(const char *cmd, char *response, int rlen, int *response_code)
  98 {
  99         char *lowbuf;
 100         int len;
 101         unsigned long flags;
 102
 103         if ((virt_to_phys(response) != (unsigned long) response) ||
 104                         (((unsigned long)response + rlen) >> 31)) {
 105                 lowbuf = kmalloc(rlen, GFP_KERNEL | GFP_DMA);
 106                 if (!lowbuf) {
 107                         pr_warning("The cpcmd kernel function failed to "
 108                                    "allocate a response buffer\n");
 109                         return -ENOMEM;
 110                 }
 111                 spin_lock_irqsave(&cpcmd_lock, flags);
 112                 len = __cpcmd(cmd, lowbuf, rlen, response_code);
 113                 spin_unlock_irqrestore(&cpcmd_lock, flags);
 114                 memcpy(response, lowbuf, rlen);
 115                 kfree(lowbuf);
 116         } else {
 117                 spin_lock_irqsave(&cpcmd_lock, flags);
 118                 len = __cpcmd(cmd, response, rlen, response_code);
 119                 spin_unlock_irqrestore(&cpcmd_lock, flags);
 120         }
 121         return len;
 122 }
 123 EXPORT_SYMBOL(cpcmd);