arch/x86/kernel/olpc_ofw.c

   1 #include <linux/kernel.h>
   2 #include <linux/module.h>
   3 #include <linux/init.h>
   4 #include <asm/page.h>
   5 #include <asm/setup.h>
   6 #include <asm/io.h>
   7 #include <asm/pgtable.h>
   8 #include <asm/olpc_ofw.h>
   9
  10 /* address of OFW callback interface; will be NULL if OFW isn't found */
  11 static int (*olpc_ofw_cif)(int *);
  12
  13 /* page dir entry containing OFW's pgdir table; filled in by head_32.S */
  14 u32 olpc_ofw_pgd __initdata;
  15
  16 static DEFINE_SPINLOCK(ofw_lock);
  17
  18 #define MAXARGS 10
  19
  20 void __init setup_olpc_ofw_pgd(void)
  21 {
  22         pgd_t *base, *ofw_pde;
  23
  24         if (!olpc_ofw_cif)
  25                 return;
  26
  27         /* fetch OFW's PDE */
  28         base = early_ioremap(olpc_ofw_pgd, sizeof(olpc_ofw_pgd) * PTRS_PER_PGD);
  29         if (!base) {
  30                 printk(KERN_ERR "failed to remap OFW's pgd - disabling OFW!\n");
  31                 olpc_ofw_cif = NULL;
  32                 return;
  33         }
  34         ofw_pde = &base[OLPC_OFW_PDE_NR];
  35
  36         /* install OFW's PDE permanently into the kernel's pgtable */
  37         set_pgd(&swapper_pg_dir[OLPC_OFW_PDE_NR], *ofw_pde);
  38         /* implicit optimization barrier here due to uninline function return */
  39
  40         early_iounmap(base, sizeof(olpc_ofw_pgd) * PTRS_PER_PGD);
  41 }
  42
  43 int __olpc_ofw(const char *name, int nr_args, const void **args, int nr_res,
  44                 void **res)
  45 {
  46         int ofw_args[MAXARGS + 3];
  47         unsigned long flags;
  48         int ret, i, *p;
  49
  50         BUG_ON(nr_args + nr_res > MAXARGS);
  51
  52         if (!olpc_ofw_cif)
  53                 return -EIO;
  54
  55         ofw_args[0] = (int)name;
  56         ofw_args[1] = nr_args;
  57         ofw_args[2] = nr_res;
  58
  59         p = &ofw_args[3];
  60         for (i = 0; i < nr_args; i++, p++)
  61                 *p = (int)args[i];
  62
  63         /* call into ofw */
  64         spin_lock_irqsave(&ofw_lock, flags);
  65         ret = olpc_ofw_cif(ofw_args);
  66         spin_unlock_irqrestore(&ofw_lock, flags);
  67
  68         if (!ret) {
  69                 for (i = 0; i < nr_res; i++, p++)
  70                         *((int *)res[i]) = *p;
  71         }
  72
  73         return ret;
  74 }
  75 EXPORT_SYMBOL_GPL(__olpc_ofw);
  76
  77 /* OFW cif _should_ be above this address */
  78 #define OFW_MIN 0xff000000
  79
  80 /* OFW starts on a 1MB boundary */
  81 #define OFW_BOUND (1<<20)
  82
  83 void __init olpc_ofw_detect(void)
  84 {
  85         struct olpc_ofw_header *hdr = &boot_params.olpc_ofw_header;
  86         unsigned long start;
  87
  88         /* ensure OFW booted us by checking for "OFW " string */
  89         if (hdr->ofw_magic != OLPC_OFW_SIG)
  90                 return;
  91
  92         olpc_ofw_cif = (int (*)(int *))hdr->cif_handler;
  93
  94         if ((unsigned long)olpc_ofw_cif < OFW_MIN) {
  95                 printk(KERN_ERR "OFW detected, but cif has invalid address 0x%lx - disabling.\n",
  96                                 (unsigned long)olpc_ofw_cif);
  97                 olpc_ofw_cif = NULL;
  98                 return;
  99         }
 100
 101         /* determine where OFW starts in memory */
 102         start = round_down((unsigned long)olpc_ofw_cif, OFW_BOUND);
 103         printk(KERN_INFO "OFW detected in memory, cif @ 0x%lx (reserving top %ldMB)\n",
 104                         (unsigned long)olpc_ofw_cif, (-start) >> 20);
 105         reserve_top_address(-start);
 106 }