arch/sparc/kernel/tadpole.c

   1 /* tadpole.c: Probing for the tadpole clock stopping h/w at boot time.
   2  *
   3  * Copyright (C) 1996 David Redman (djhr@tadpole.co.uk)
   4  */
   5
   6 #include <linux/string.h>
   7 #include <linux/kernel.h>
   8 #include <linux/sched.h>
   9 #include <linux/init.h>
  10
  11 #include <asm/asi.h>
  12 #include <asm/oplib.h>
  13 #include <asm/io.h>
  14
  15 #define MACIO_SCSI_CSR_ADDR     0x78400000
  16 #define MACIO_EN_DMA            0x00000200
  17 #define CLOCK_INIT_DONE         1
  18
  19 static int clk_state;
  20 static volatile unsigned char *clk_ctrl;
  21 void (*cpu_pwr_save)(void);
  22
  23 static inline unsigned int ldphys(unsigned int addr)
  24 {
  25         unsigned long data;
  26
  27         __asm__ __volatile__("\n\tlda [%1] %2, %0\n\t" :
  28                              "=r" (data) :
  29                              "r" (addr), "i" (ASI_M_BYPASS));
  30         return data;
  31 }
  32
  33 static void clk_init(void)
  34 {
  35         __asm__ __volatile__("mov 0x6c, %%g1\n\t"
  36                              "mov 0x4c, %%g2\n\t"
  37                              "mov 0xdf, %%g3\n\t"
  38                              "stb %%g1, [%0+3]\n\t"
  39                              "stb %%g2, [%0+3]\n\t"
  40                              "stb %%g3, [%0+3]\n\t" : :
  41                              "r" (clk_ctrl) :
  42                              "g1", "g2", "g3");
  43 }
  44
  45 static void clk_slow(void)
  46 {
  47         __asm__ __volatile__("mov 0xcc, %%g2\n\t"
  48                              "mov 0x4c, %%g3\n\t"
  49                              "mov 0xcf, %%g4\n\t"
  50                              "mov 0xdf, %%g5\n\t"
  51                              "stb %%g2, [%0+3]\n\t"
  52                              "stb %%g3, [%0+3]\n\t"
  53                              "stb %%g4, [%0+3]\n\t"
  54                              "stb %%g5, [%0+3]\n\t" : :
  55                              "r" (clk_ctrl) :
  56                              "g2", "g3", "g4", "g5");
  57 }
  58
  59 /*
  60  * Tadpole is guaranteed to be UP, using local_irq_save.
  61  */
  62 static void tsu_clockstop(void)
  63 {
  64         unsigned int mcsr;
  65         unsigned long flags;
  66
  67         if (!clk_ctrl)
  68                 return;
  69         if (!(clk_state & CLOCK_INIT_DONE)) {
  70                 local_irq_save(flags);
  71                 clk_init();
  72                 clk_state |= CLOCK_INIT_DONE;       /* all done */
  73                 local_irq_restore(flags);
  74                 return;
  75         }
  76         if (!(clk_ctrl[2] & 1))
  77                 return;               /* no speed up yet */
  78
  79         local_irq_save(flags);
  80
  81         /* if SCSI DMA in progress, don't slow clock */
  82         mcsr = ldphys(MACIO_SCSI_CSR_ADDR);
  83         if ((mcsr&MACIO_EN_DMA) != 0) {
  84                 local_irq_restore(flags);
  85                 return;
  86         }
  87         /* TODO... the minimum clock setting ought to increase the
  88          * memory refresh interval..
  89          */
  90         clk_slow();
  91         local_irq_restore(flags);
  92 }
  93
  94 static void swift_clockstop(void)
  95 {
  96         if (!clk_ctrl)
  97                 return;
  98         clk_ctrl[0] = 0;
  99 }
 100
 101 void __init clock_stop_probe(void)
 102 {
 103         phandle node, clk_nd;
 104         char name[20];
 105
 106         prom_getstring(prom_root_node, "name", name, sizeof(name));
 107         if (strncmp(name, "Tadpole", 7))
 108                 return;
 109         node = prom_getchild(prom_root_node);
 110         node = prom_searchsiblings(node, "obio");
 111         node = prom_getchild(node);
 112         clk_nd = prom_searchsiblings(node, "clk-ctrl");
 113         if (!clk_nd)
 114                 return;
 115         printk("Clock Stopping h/w detected... ");
 116         clk_ctrl = (char *) prom_getint(clk_nd, "address");
 117         clk_state = 0;
 118         if (name[10] == '\0') {
 119                 cpu_pwr_save = tsu_clockstop;
 120                 printk("enabled (S3)\n");
 121         } else if ((name[10] == 'X') || (name[10] == 'G')) {
 122                 cpu_pwr_save = swift_clockstop;
 123                 printk("enabled (%s)\n",name+7);
 124         } else
 125                 printk("disabled %s\n",name+7);
 126 }