1 // SPDX-License-Identifier: GPL-2.0
3 * Support for periodic interrupts (100 per second) and for getting
4 * the current time from the RTC on Power Macintoshes.
6 * We use the decrementer register for our periodic interrupts.
8 * Paul Mackerras August 1996.
9 * Copyright (C) 1996 Paul Mackerras.
10 * Copyright (C) 2003-2005 Benjamin Herrenschmidt.
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>
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>
28 #include <asm/sections.h>
31 #include <asm/pgtable.h>
32 #include <asm/machdep.h>
34 #include <asm/nvram.h>
42 #define DBG(x...) printk(x)
48 * Calibrate the decrementer frequency with the VIA timer 1.
50 #define VIA_TIMER_FREQ_6 4700000 /* time 1 frequency * 6 */
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 */
62 #define T1MODE 0xc0 /* Timer 1 mode */
63 #define T1MODE_CONT 0x40 /* continuous interrupts */
65 /* Bits in IFR and IER */
66 #define T1_INT 0x40 /* Timer 1 interrupt */
68 long __init pmac_time_init(void)
71 #if defined(CONFIG_NVRAM) && defined(CONFIG_PPC32)
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,
86 #ifdef CONFIG_PMAC_SMU
87 static time64_t smu_get_time(void)
91 if (smu_get_rtc_time(&tm, 1))
93 return rtc_tm_to_time64(&tm);
97 /* Can't be __init, it's called when suspending and resuming */
98 time64_t pmac_get_boot_time(void)
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();
106 #ifdef CONFIG_ADB_PMU
108 return pmu_get_time();
110 #ifdef CONFIG_PMAC_SMU
112 return smu_get_time();
119 void pmac_get_rtc_time(struct rtc_time *tm)
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);
128 #ifdef CONFIG_ADB_PMU
130 rtc_time64_to_tm(pmu_get_time(), tm);
133 #ifdef CONFIG_PMAC_SMU
135 smu_get_rtc_time(tm, 1);
143 int pmac_set_rtc_time(struct rtc_time *tm)
145 switch (sys_ctrler) {
146 #ifdef CONFIG_ADB_CUDA
147 case SYS_CTRLER_CUDA:
148 return cuda_set_rtc_time(tm);
150 #ifdef CONFIG_ADB_PMU
152 return pmu_set_rtc_time(tm);
154 #ifdef CONFIG_PMAC_SMU
156 return smu_set_rtc_time(tm, 1);
165 * Calibrate the decrementer register using VIA timer 1.
166 * This is used both on powermacs and CHRP machines.
168 static int __init via_calibrate_decr(void)
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;
176 vias = of_find_node_by_name(NULL, "via-cuda");
178 vias = of_find_node_by_name(NULL, "via-pmu");
180 vias = of_find_node_by_name(NULL, "via");
181 if (vias == NULL || of_address_to_resource(vias, 0, &rsrc)) {
186 via = ioremap(rsrc.start, resource_size(&rsrc));
188 printk(KERN_ERR "Failed to map VIA for timer calibration !\n");
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)
203 /* clear the interrupt & wait until it hits 0 again */
205 while ((in_8(&via[IFR]) & T1_INT) == 0)
209 ppc_tb_freq = (dstart - dend) * 100 / 6;
218 * Query the OF and get the decr frequency.
220 void __init pmac_calibrate_decr(void)
222 generic_calibrate_decr();
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
229 if (!of_machine_is_compatible("MacRISC2") &&
230 !of_machine_is_compatible("MacRISC3") &&
231 !of_machine_is_compatible("MacRISC4"))
232 if (via_calibrate_decr())
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
240 if (of_machine_is_compatible("PowerMac3,5"))
241 if (via_calibrate_decr())