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/string_choices.h>
19#include <linux/mm.h>
20#include <linux/init.h>
21#include <linux/time.h>
22#include <linux/adb.h>
23#include <linux/cuda.h>
24#include <linux/pmu.h>
25#include <linux/interrupt.h>
26#include <linux/hardirq.h>
27#include <linux/rtc.h>
28#include <linux/of_address.h>
29
30#include <asm/early_ioremap.h>
31#include <asm/sections.h>
32#include <asm/machdep.h>
33#include <asm/time.h>
34#include <asm/nvram.h>
35#include <asm/smu.h>
36
37#include "pmac.h"
38
39#undef DEBUG
40
41#ifdef DEBUG
42#define DBG(x...) printk(x)
43#else
44#define DBG(x...)
45#endif
46
47/*
48 * Calibrate the decrementer frequency with the VIA timer 1.
49 */
50#define VIA_TIMER_FREQ_6 4700000 /* time 1 frequency * 6 */
51
52/* VIA registers */
53#define RS 0x200 /* skip between registers */
54#define T1CL (4*RS) /* Timer 1 ctr/latch (low 8 bits) */
55#define T1CH (5*RS) /* Timer 1 counter (high 8 bits) */
56#define T1LL (6*RS) /* Timer 1 latch (low 8 bits) */
57#define T1LH (7*RS) /* Timer 1 latch (high 8 bits) */
58#define ACR (11*RS) /* Auxiliary control register */
59#define IFR (13*RS) /* Interrupt flag register */
60
61/* Bits in ACR */
62#define T1MODE 0xc0 /* Timer 1 mode */
63#define T1MODE_CONT 0x40 /* continuous interrupts */
64
65/* Bits in IFR and IER */
66#define T1_INT 0x40 /* Timer 1 interrupt */
67
68long __init pmac_time_init(void)
69{
70 s32 delta = 0;
71#if defined(CONFIG_NVRAM) && defined(CONFIG_PPC32)
72 int dst;
73
74 delta = ((s32)pmac_xpram_read(PMAC_XPRAM_MACHINE_LOC + 0x9)) << 16;
75 delta |= ((s32)pmac_xpram_read(PMAC_XPRAM_MACHINE_LOC + 0xa)) << 8;
76 delta |= pmac_xpram_read(PMAC_XPRAM_MACHINE_LOC + 0xb);
77 if (delta & 0x00800000UL)
78 delta |= 0xFF000000UL;
79 dst = ((pmac_xpram_read(PMAC_XPRAM_MACHINE_LOC + 0x8) & 0x80) != 0);
80 printk("GMT Delta read from XPRAM: %d minutes, DST: %s\n", delta/60,
81 str_on_off(dst));
82#endif
83 return delta;
84}
85
86#ifdef CONFIG_PMAC_SMU
87static time64_t smu_get_time(void)
88{
89 struct rtc_time tm;
90
91 if (smu_get_rtc_time(&tm, 1))
92 return 0;
93 return rtc_tm_to_time64(&tm);
94}
95#endif
96
97/* Can't be __init, it's called when suspending and resuming */
98time64_t pmac_get_boot_time(void)
99{
100 /* Get the time from the RTC, used only at boot time */
101 switch (sys_ctrler) {
102#ifdef CONFIG_ADB_CUDA
103 case SYS_CTRLER_CUDA:
104 return cuda_get_time();
105#endif
106#ifdef CONFIG_ADB_PMU
107 case SYS_CTRLER_PMU:
108 return pmu_get_time();
109#endif
110#ifdef CONFIG_PMAC_SMU
111 case SYS_CTRLER_SMU:
112 return smu_get_time();
113#endif
114 default:
115 return 0;
116 }
117}
118
119void pmac_get_rtc_time(struct rtc_time *tm)
120{
121 /* Get the time from the RTC, used only at boot time */
122 switch (sys_ctrler) {
123#ifdef CONFIG_ADB_CUDA
124 case SYS_CTRLER_CUDA:
125 rtc_time64_to_tm(cuda_get_time(), tm);
126 break;
127#endif
128#ifdef CONFIG_ADB_PMU
129 case SYS_CTRLER_PMU:
130 rtc_time64_to_tm(pmu_get_time(), tm);
131 break;
132#endif
133#ifdef CONFIG_PMAC_SMU
134 case SYS_CTRLER_SMU:
135 smu_get_rtc_time(tm, 1);
136 break;
137#endif
138 default:
139 ;
140 }
141}
142
143int pmac_set_rtc_time(struct rtc_time *tm)
144{
145 switch (sys_ctrler) {
146#ifdef CONFIG_ADB_CUDA
147 case SYS_CTRLER_CUDA:
148 return cuda_set_rtc_time(tm);
149#endif
150#ifdef CONFIG_ADB_PMU
151 case SYS_CTRLER_PMU:
152 return pmu_set_rtc_time(tm);
153#endif
154#ifdef CONFIG_PMAC_SMU
155 case SYS_CTRLER_SMU:
156 return smu_set_rtc_time(tm, 1);
157#endif
158 default:
159 return -ENODEV;
160 }
161}
162
163#ifdef CONFIG_PPC32
164/*
165 * Calibrate the decrementer register using VIA timer 1.
166 * This is used both on powermacs and CHRP machines.
167 */
168static int __init via_calibrate_decr(void)
169{
170 struct device_node *vias;
171 volatile unsigned char __iomem *via;
172 int count = VIA_TIMER_FREQ_6 / 100;
173 unsigned int dstart, dend;
174 struct resource rsrc;
175
176 vias = of_find_node_by_name(NULL, "via-cuda");
177 if (vias == NULL)
178 vias = of_find_node_by_name(NULL, "via-pmu");
179 if (vias == NULL)
180 vias = of_find_node_by_name(NULL, "via");
181 if (vias == NULL || of_address_to_resource(vias, 0, &rsrc)) {
182 of_node_put(vias);
183 return 0;
184 }
185 of_node_put(vias);
186 via = early_ioremap(rsrc.start, resource_size(&rsrc));
187 if (via == NULL) {
188 printk(KERN_ERR "Failed to map VIA for timer calibration !\n");
189 return 0;
190 }
191
192 /* set timer 1 for continuous interrupts */
193 out_8(&via[ACR], (via[ACR] & ~T1MODE) | T1MODE_CONT);
194 /* set the counter to a small value */
195 out_8(&via[T1CH], 2);
196 /* set the latch to `count' */
197 out_8(&via[T1LL], count);
198 out_8(&via[T1LH], count >> 8);
199 /* wait until it hits 0 */
200 while ((in_8(&via[IFR]) & T1_INT) == 0)
201 ;
202 dstart = get_dec();
203 /* clear the interrupt & wait until it hits 0 again */
204 in_8(&via[T1CL]);
205 while ((in_8(&via[IFR]) & T1_INT) == 0)
206 ;
207 dend = get_dec();
208
209 ppc_tb_freq = (dstart - dend) * 100 / 6;
210
211 early_iounmap((void *)via, resource_size(&rsrc));
212
213 return 1;
214}
215#endif
216
217/*
218 * Query the OF and get the decr frequency.
219 */
220void __init pmac_calibrate_decr(void)
221{
222 generic_calibrate_decr();
223
224#ifdef CONFIG_PPC32
225 /* We assume MacRISC2 machines have correct device-tree
226 * calibration. That's better since the VIA itself seems
227 * to be slightly off. --BenH
228 */
229 if (!of_machine_is_compatible("MacRISC2") &&
230 !of_machine_is_compatible("MacRISC3") &&
231 !of_machine_is_compatible("MacRISC4"))
232 if (via_calibrate_decr())
233 return;
234
235 /* Special case: QuickSilver G4s seem to have a badly calibrated
236 * timebase-frequency in OF, VIA is much better on these. We should
237 * probably implement calibration based on the KL timer on these
238 * machines anyway... -BenH
239 */
240 if (of_machine_is_compatible("PowerMac3,5"))
241 if (via_calibrate_decr())
242 return;
243#endif
244}
245

source code of linux/arch/powerpc/platforms/powermac/time.c