1 /* tadpole.c: Probing for the tadpole clock stopping h/w at boot time.
3 * Copyright (C) 1996 David Redman (djhr@tadpole.co.uk)
6 #include <linux/string.h>
7 #include <linux/kernel.h>
8 #include <linux/sched.h>
9 #include <linux/init.h>
12 #include <asm/oplib.h>
15 #define MACIO_SCSI_CSR_ADDR 0x78400000
16 #define MACIO_EN_DMA 0x00000200
17 #define CLOCK_INIT_DONE 1
20 static volatile unsigned char *clk_ctrl;
21 void (*cpu_pwr_save)(void);
23 static inline unsigned int ldphys(unsigned int addr)
27 __asm__ __volatile__("\n\tlda [%1] %2, %0\n\t" :
29 "r" (addr), "i" (ASI_M_BYPASS));
33 static void clk_init(void)
35 __asm__ __volatile__("mov 0x6c, %%g1\n\t"
38 "stb %%g1, [%0+3]\n\t"
39 "stb %%g2, [%0+3]\n\t"
40 "stb %%g3, [%0+3]\n\t" : :
45 static void clk_slow(void)
47 __asm__ __volatile__("mov 0xcc, %%g2\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" : :
56 "g2", "g3", "g4", "g5");
59 static void tsu_clockstop(void)
66 if (!(clk_state & CLOCK_INIT_DONE)) {
69 clk_state |= CLOCK_INIT_DONE; /* all done */
73 if (!(clk_ctrl[2] & 1))
74 return; /* no speed up yet */
78 /* if SCSI DMA in progress, don't slow clock */
79 mcsr = ldphys(MACIO_SCSI_CSR_ADDR);
80 if ((mcsr&MACIO_EN_DMA) != 0) {
84 /* TODO... the minimum clock setting ought to increase the
85 * memory refresh interval..
91 static void swift_clockstop(void)
98 void __init clock_stop_probe(void)
100 unsigned int node, clk_nd;
103 prom_getstring(prom_root_node, "name", name, sizeof(name));
104 if (strncmp(name, "Tadpole", 7))
106 node = prom_getchild(prom_root_node);
107 node = prom_searchsiblings(node, "obio");
108 node = prom_getchild(node);
109 clk_nd = prom_searchsiblings(node, "clk-ctrl");
112 printk("Clock Stopping h/w detected... ");
113 clk_ctrl = (char *) prom_getint(clk_nd, "address");
115 if (name[10] == '\0') {
116 cpu_pwr_save = tsu_clockstop;
117 printk("enabled (S3)\n");
118 } else if ((name[10] == 'X') || (name[10] == 'G')) {
119 cpu_pwr_save = swift_clockstop;
120 printk("enabled (%s)\n",name+7);
122 printk("disabled %s\n",name+7);