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
ldphys(unsigned int addr)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
clk_init(void)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
clk_slow(void)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 */
tsu_clockstop(void)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
swift_clockstop(void)94 static void swift_clockstop(void)
95 {
96 if (!clk_ctrl)
97 return;
98 clk_ctrl[0] = 0;
99 }
100
clock_stop_probe(void)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 }
127