1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Support for periodic interrupts (100 per second) and for getting
4  * the current time from the RTC on Power Macintoshes.
5  *
6  * We use the decrementer register for our periodic interrupts.
7  *
8  * Paul Mackerras	August 1996.
9  * Copyright (C) 1996 Paul Mackerras.
10  * Copyright (C) 2003-2005 Benjamin Herrenschmidt.
11  *
12  */
13 #include <linux/errno.h>
14 #include <linux/sched.h>
15 #include <linux/kernel.h>
16 #include <linux/param.h>
17 #include <linux/string.h>
18 #include <linux/mm.h>
19 #include <linux/init.h>
20 #include <linux/time.h>
21 #include <linux/adb.h>
22 #include <linux/cuda.h>
23 #include <linux/pmu.h>
24 #include <linux/interrupt.h>
25 #include <linux/hardirq.h>
26 #include <linux/rtc.h>
27 #include <linux/of_address.h>
28 
29 #include <asm/early_ioremap.h>
30 #include <asm/sections.h>
31 #include <asm/machdep.h>
32 #include <asm/time.h>
33 #include <asm/nvram.h>
34 #include <asm/smu.h>
35 
36 #include "pmac.h"
37 
38 #undef DEBUG
39 
40 #ifdef DEBUG
41 #define DBG(x...) printk(x)
42 #else
43 #define DBG(x...)
44 #endif
45 
46 /*
47  * Calibrate the decrementer frequency with the VIA timer 1.
48  */
49 #define VIA_TIMER_FREQ_6	4700000	/* time 1 frequency * 6 */
50 
51 /* VIA registers */
52 #define RS		0x200		/* skip between registers */
53 #define T1CL		(4*RS)		/* Timer 1 ctr/latch (low 8 bits) */
54 #define T1CH		(5*RS)		/* Timer 1 counter (high 8 bits) */
55 #define T1LL		(6*RS)		/* Timer 1 latch (low 8 bits) */
56 #define T1LH		(7*RS)		/* Timer 1 latch (high 8 bits) */
57 #define ACR		(11*RS)		/* Auxiliary control register */
58 #define IFR		(13*RS)		/* Interrupt flag register */
59 
60 /* Bits in ACR */
61 #define T1MODE		0xc0		/* Timer 1 mode */
62 #define T1MODE_CONT	0x40		/*  continuous interrupts */
63 
64 /* Bits in IFR and IER */
65 #define T1_INT		0x40		/* Timer 1 interrupt */
66 
67 long __init pmac_time_init(void)
68 {
69 	s32 delta = 0;
70 #if defined(CONFIG_NVRAM) && defined(CONFIG_PPC32)
71 	int dst;
72 
73 	delta = ((s32)pmac_xpram_read(PMAC_XPRAM_MACHINE_LOC + 0x9)) << 16;
74 	delta |= ((s32)pmac_xpram_read(PMAC_XPRAM_MACHINE_LOC + 0xa)) << 8;
75 	delta |= pmac_xpram_read(PMAC_XPRAM_MACHINE_LOC + 0xb);
76 	if (delta & 0x00800000UL)
77 		delta |= 0xFF000000UL;
78 	dst = ((pmac_xpram_read(PMAC_XPRAM_MACHINE_LOC + 0x8) & 0x80) != 0);
79 	printk("GMT Delta read from XPRAM: %d minutes, DST: %s\n", delta/60,
80 		dst ? "on" : "off");
81 #endif
82 	return delta;
83 }
84 
85 #ifdef CONFIG_PMAC_SMU
86 static time64_t smu_get_time(void)
87 {
88 	struct rtc_time tm;
89 
90 	if (smu_get_rtc_time(&tm, 1))
91 		return 0;
92 	return rtc_tm_to_time64(&tm);
93 }
94 #endif
95 
96 /* Can't be __init, it's called when suspending and resuming */
97 time64_t pmac_get_boot_time(void)
98 {
99 	/* Get the time from the RTC, used only at boot time */
100 	switch (sys_ctrler) {
101 #ifdef CONFIG_ADB_CUDA
102 	case SYS_CTRLER_CUDA:
103 		return cuda_get_time();
104 #endif
105 #ifdef CONFIG_ADB_PMU
106 	case SYS_CTRLER_PMU:
107 		return pmu_get_time();
108 #endif
109 #ifdef CONFIG_PMAC_SMU
110 	case SYS_CTRLER_SMU:
111 		return smu_get_time();
112 #endif
113 	default:
114 		return 0;
115 	}
116 }
117 
118 void pmac_get_rtc_time(struct rtc_time *tm)
119 {
120 	/* Get the time from the RTC, used only at boot time */
121 	switch (sys_ctrler) {
122 #ifdef CONFIG_ADB_CUDA
123 	case SYS_CTRLER_CUDA:
124 		rtc_time64_to_tm(cuda_get_time(), tm);
125 		break;
126 #endif
127 #ifdef CONFIG_ADB_PMU
128 	case SYS_CTRLER_PMU:
129 		rtc_time64_to_tm(pmu_get_time(), tm);
130 		break;
131 #endif
132 #ifdef CONFIG_PMAC_SMU
133 	case SYS_CTRLER_SMU:
134 		smu_get_rtc_time(tm, 1);
135 		break;
136 #endif
137 	default:
138 		;
139 	}
140 }
141 
142 int pmac_set_rtc_time(struct rtc_time *tm)
143 {
144 	switch (sys_ctrler) {
145 #ifdef CONFIG_ADB_CUDA
146 	case SYS_CTRLER_CUDA:
147 		return cuda_set_rtc_time(tm);
148 #endif
149 #ifdef CONFIG_ADB_PMU
150 	case SYS_CTRLER_PMU:
151 		return pmu_set_rtc_time(tm);
152 #endif
153 #ifdef CONFIG_PMAC_SMU
154 	case SYS_CTRLER_SMU:
155 		return smu_set_rtc_time(tm, 1);
156 #endif
157 	default:
158 		return -ENODEV;
159 	}
160 }
161 
162 #ifdef CONFIG_PPC32
163 /*
164  * Calibrate the decrementer register using VIA timer 1.
165  * This is used both on powermacs and CHRP machines.
166  */
167 static int __init via_calibrate_decr(void)
168 {
169 	struct device_node *vias;
170 	volatile unsigned char __iomem *via;
171 	int count = VIA_TIMER_FREQ_6 / 100;
172 	unsigned int dstart, dend;
173 	struct resource rsrc;
174 
175 	vias = of_find_node_by_name(NULL, "via-cuda");
176 	if (vias == NULL)
177 		vias = of_find_node_by_name(NULL, "via-pmu");
178 	if (vias == NULL)
179 		vias = of_find_node_by_name(NULL, "via");
180 	if (vias == NULL || of_address_to_resource(vias, 0, &rsrc)) {
181 	        of_node_put(vias);
182 		return 0;
183 	}
184 	of_node_put(vias);
185 	via = early_ioremap(rsrc.start, resource_size(&rsrc));
186 	if (via == NULL) {
187 		printk(KERN_ERR "Failed to map VIA for timer calibration !\n");
188 		return 0;
189 	}
190 
191 	/* set timer 1 for continuous interrupts */
192 	out_8(&via[ACR], (via[ACR] & ~T1MODE) | T1MODE_CONT);
193 	/* set the counter to a small value */
194 	out_8(&via[T1CH], 2);
195 	/* set the latch to `count' */
196 	out_8(&via[T1LL], count);
197 	out_8(&via[T1LH], count >> 8);
198 	/* wait until it hits 0 */
199 	while ((in_8(&via[IFR]) & T1_INT) == 0)
200 		;
201 	dstart = get_dec();
202 	/* clear the interrupt & wait until it hits 0 again */
203 	in_8(&via[T1CL]);
204 	while ((in_8(&via[IFR]) & T1_INT) == 0)
205 		;
206 	dend = get_dec();
207 
208 	ppc_tb_freq = (dstart - dend) * 100 / 6;
209 
210 	early_iounmap((void *)via, resource_size(&rsrc));
211 
212 	return 1;
213 }
214 #endif
215 
216 /*
217  * Query the OF and get the decr frequency.
218  */
219 void __init pmac_calibrate_decr(void)
220 {
221 	generic_calibrate_decr();
222 
223 #ifdef CONFIG_PPC32
224 	/* We assume MacRISC2 machines have correct device-tree
225 	 * calibration. That's better since the VIA itself seems
226 	 * to be slightly off. --BenH
227 	 */
228 	if (!of_machine_is_compatible("MacRISC2") &&
229 	    !of_machine_is_compatible("MacRISC3") &&
230 	    !of_machine_is_compatible("MacRISC4"))
231 		if (via_calibrate_decr())
232 			return;
233 
234 	/* Special case: QuickSilver G4s seem to have a badly calibrated
235 	 * timebase-frequency in OF, VIA is much better on these. We should
236 	 * probably implement calibration based on the KL timer on these
237 	 * machines anyway... -BenH
238 	 */
239 	if (of_machine_is_compatible("PowerMac3,5"))
240 		if (via_calibrate_decr())
241 			return;
242 #endif
243 }
244