arch/x86/platform/olpc/olpc_ofw.c

   1 #include <linux/kernel.h>
   2 #include <linux/export.h>
   3 #include <linux/spinlock_types.h>
   4 #include <linux/init.h>
   5 #include <asm/page.h>
   6 #include <asm/setup.h>
   7 #include <asm/io.h>
   8 #include <asm/cpufeature.h>
   9 #include <asm/special_insns.h>
  10 #include <asm/pgtable.h>
  11 #include <asm/olpc_ofw.h>
  12
  13 /* address of OFW callback interface; will be NULL if OFW isn't found */
  14 static int (*olpc_ofw_cif)(int *);
  15
  16 /* page dir entry containing OFW's pgdir table; filled in by head_32.S */
  17 u32 olpc_ofw_pgd __initdata;
  18
  19 static DEFINE_SPINLOCK(ofw_lock);
  20
  21 #define MAXARGS 10
  22
  23 void __init setup_olpc_ofw_pgd(void)
  24 {
  25         pgd_t *base, *ofw_pde;
  26
  27         if (!olpc_ofw_cif)
  28                 return;
  29
  30         /* fetch OFW's PDE */
  31         base = early_ioremap(olpc_ofw_pgd, sizeof(olpc_ofw_pgd) * PTRS_PER_PGD);
  32         if (!base) {
  33                 printk(KERN_ERR "failed to remap OFW's pgd - disabling OFW!\n");
  34                 olpc_ofw_cif = NULL;
  35                 return;
  36         }
  37         ofw_pde = &base[OLPC_OFW_PDE_NR];
  38
  39         /* install OFW's PDE permanently into the kernel's pgtable */
  40         set_pgd(&swapper_pg_dir[OLPC_OFW_PDE_NR], *ofw_pde);
  41         /* implicit optimization barrier here due to uninline function return */
  42
  43         early_iounmap(base, sizeof(olpc_ofw_pgd) * PTRS_PER_PGD);
  44 }
  45
  46 int __olpc_ofw(const char *name, int nr_args, const void **args, int nr_res,
  47                 void **res)
  48 {
  49         int ofw_args[MAXARGS + 3];
  50         unsigned long flags;
  51         int ret, i, *p;
  52
  53         BUG_ON(nr_args + nr_res > MAXARGS);
  54
  55         if (!olpc_ofw_cif)
  56                 return -EIO;
  57
  58         ofw_args[0] = (int)name;
  59         ofw_args[1] = nr_args;
  60         ofw_args[2] = nr_res;
  61
  62         p = &ofw_args[3];
  63         for (i = 0; i < nr_args; i++, p++)
  64                 *p = (int)args[i];
  65
  66         /* call into ofw */
  67         spin_lock_irqsave(&ofw_lock, flags);
  68         ret = olpc_ofw_cif(ofw_args);
  69         spin_unlock_irqrestore(&ofw_lock, flags);
  70
  71         if (!ret) {
  72                 for (i = 0; i < nr_res; i++, p++)
  73                         *((int *)res[i]) = *p;
  74         }
  75
  76         return ret;
  77 }
  78 EXPORT_SYMBOL_GPL(__olpc_ofw);
  79
  80 bool olpc_ofw_present(void)
  81 {
  82         return olpc_ofw_cif != NULL;
  83 }
  84 EXPORT_SYMBOL_GPL(olpc_ofw_present);
  85
  86 /* OFW cif _should_ be above this address */
  87 #define OFW_MIN 0xff000000
  88
  89 /* OFW starts on a 1MB boundary */
  90 #define OFW_BOUND (1<<20)
  91
  92 void __init olpc_ofw_detect(void)
  93 {
  94         struct olpc_ofw_header *hdr = &boot_params.olpc_ofw_header;
  95         unsigned long start;
  96
  97         /* ensure OFW booted us by checking for "OFW " string */
  98         if (hdr->ofw_magic != OLPC_OFW_SIG)
  99                 return;
 100
 101         olpc_ofw_cif = (int (*)(int *))hdr->cif_handler;
 102
 103         if ((unsigned long)olpc_ofw_cif < OFW_MIN) {
 104                 printk(KERN_ERR "OFW detected, but cif has invalid address 0x%lx - disabling.\n",
 105                                 (unsigned long)olpc_ofw_cif);
 106                 olpc_ofw_cif = NULL;
 107                 return;
 108         }
 109
 110         /* determine where OFW starts in memory */
 111         start = round_down((unsigned long)olpc_ofw_cif, OFW_BOUND);
 112         printk(KERN_INFO "OFW detected in memory, cif @ 0x%lx (reserving top %ldMB)\n",
 113                         (unsigned long)olpc_ofw_cif, (-start) >> 20);
 114         reserve_top_address(-start);
 115 }
 116
 117 bool __init olpc_ofw_is_installed(void)
 118 {
 119         return olpc_ofw_cif != NULL;
 120 }