arch/x86/platform/olpc/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 bool olpc_ofw_present(void)
  78 {
  79         return olpc_ofw_cif != NULL;
  80 }
  81 EXPORT_SYMBOL_GPL(olpc_ofw_present);
  82
  83 /* OFW cif _should_ be above this address */
  84 #define OFW_MIN 0xff000000
  85
  86 /* OFW starts on a 1MB boundary */
  87 #define OFW_BOUND (1<<20)
  88
  89 void __init olpc_ofw_detect(void)
  90 {
  91         struct olpc_ofw_header *hdr = &boot_params.olpc_ofw_header;
  92         unsigned long start;
  93
  94         /* ensure OFW booted us by checking for "OFW " string */
  95         if (hdr->ofw_magic != OLPC_OFW_SIG)
  96                 return;
  97
  98         olpc_ofw_cif = (int (*)(int *))hdr->cif_handler;
  99
 100         if ((unsigned long)olpc_ofw_cif < OFW_MIN) {
 101                 printk(KERN_ERR "OFW detected, but cif has invalid address 0x%lx - disabling.\n",
 102                                 (unsigned long)olpc_ofw_cif);
 103                 olpc_ofw_cif = NULL;
 104                 return;
 105         }
 106
 107         /* determine where OFW starts in memory */
 108         start = round_down((unsigned long)olpc_ofw_cif, OFW_BOUND);
 109         printk(KERN_INFO "OFW detected in memory, cif @ 0x%lx (reserving top %ldMB)\n",
 110                         (unsigned long)olpc_ofw_cif, (-start) >> 20);
 111         reserve_top_address(-start);
 112 }
 113
 114 bool __init olpc_ofw_is_installed(void)
 115 {
 116         return olpc_ofw_cif != NULL;
 117 }