1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Carsten Langgaard, carstenl@mips.com
4 * Copyright (C) 1999,2000 MIPS Technologies, Inc. All rights reserved.
5 *
6 * Setting up the clock on the MIPS boards.
7 */
8#include <linux/types.h>
9#include <linux/i8253.h>
10#include <linux/init.h>
11#include <linux/kernel_stat.h>
12#include <linux/libfdt.h>
13#include <linux/math64.h>
14#include <linux/sched.h>
15#include <linux/spinlock.h>
16#include <linux/interrupt.h>
17#include <linux/timex.h>
18#include <linux/mc146818rtc.h>
19
20#include <asm/cpu.h>
21#include <asm/mipsregs.h>
22#include <asm/mipsmtregs.h>
23#include <asm/hardirq.h>
24#include <asm/irq.h>
25#include <asm/div64.h>
26#include <asm/setup.h>
27#include <asm/time.h>
28#include <asm/mc146818-time.h>
29#include <asm/msc01_ic.h>
30#include <asm/mips-cps.h>
31
32#include <asm/mips-boards/generic.h>
33#include <asm/mips-boards/maltaint.h>
34
35static int mips_cpu_timer_irq;
36static int mips_cpu_perf_irq;
37extern int cp0_perfcount_irq;
38
39static unsigned int gic_frequency;
40
41static void mips_timer_dispatch(void)
42{
43 do_IRQ(mips_cpu_timer_irq);
44}
45
46static void mips_perf_dispatch(void)
47{
48 do_IRQ(mips_cpu_perf_irq);
49}
50
51static unsigned int freqround(unsigned int freq, unsigned int amount)
52{
53 freq += amount;
54 freq -= freq % (amount*2);
55 return freq;
56}
57
58/*
59 * Estimate CPU and GIC frequencies.
60 */
61static void __init estimate_frequencies(void)
62{
63 unsigned long flags;
64 unsigned int count, start;
65 unsigned char secs1, secs2, ctrl;
66 int secs;
67 u64 giccount = 0, gicstart = 0;
68
69 local_irq_save(flags);
70
71 if (mips_gic_present())
72 clear_gic_config(GIC_CONFIG_COUNTSTOP);
73
74 /*
75 * Read counters exactly on rising edge of update flag.
76 * This helps get an accurate reading under virtualisation.
77 */
78 while (CMOS_READ(RTC_REG_A) & RTC_UIP);
79 while (!(CMOS_READ(RTC_REG_A) & RTC_UIP));
80 start = read_c0_count();
81 if (mips_gic_present())
82 gicstart = read_gic_counter();
83
84 /* Wait for falling edge before reading RTC. */
85 while (CMOS_READ(RTC_REG_A) & RTC_UIP);
86 secs1 = CMOS_READ(RTC_SECONDS);
87
88 /* Read counters again exactly on rising edge of update flag. */
89 while (!(CMOS_READ(RTC_REG_A) & RTC_UIP));
90 count = read_c0_count();
91 if (mips_gic_present())
92 giccount = read_gic_counter();
93
94 /* Wait for falling edge before reading RTC again. */
95 while (CMOS_READ(RTC_REG_A) & RTC_UIP);
96 secs2 = CMOS_READ(RTC_SECONDS);
97
98 ctrl = CMOS_READ(RTC_CONTROL);
99
100 local_irq_restore(flags);
101
102 if (!(ctrl & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
103 secs1 = bcd2bin(secs1);
104 secs2 = bcd2bin(secs2);
105 }
106 secs = secs2 - secs1;
107 if (secs < 1)
108 secs += 60;
109
110 count -= start;
111 count /= secs;
112 mips_hpt_frequency = count;
113
114 if (mips_gic_present()) {
115 giccount = div_u64(dividend: giccount - gicstart, divisor: secs);
116 gic_frequency = giccount;
117 }
118}
119
120void read_persistent_clock64(struct timespec64 *ts)
121{
122 ts->tv_sec = mc146818_get_cmos_time();
123 ts->tv_nsec = 0;
124}
125
126int get_c0_fdc_int(void)
127{
128 /*
129 * Some cores claim the FDC is routable through the GIC, but it doesn't
130 * actually seem to be connected for those Malta bitstreams.
131 */
132 switch (current_cpu_type()) {
133 case CPU_INTERAPTIV:
134 case CPU_PROAPTIV:
135 return -1;
136 }
137
138 if (cpu_has_veic)
139 return -1;
140 else if (mips_gic_present())
141 return gic_get_c0_fdc_int();
142 else if (cp0_fdc_irq >= 0)
143 return MIPS_CPU_IRQ_BASE + cp0_fdc_irq;
144 else
145 return -1;
146}
147
148int get_c0_perfcount_int(void)
149{
150 if (cpu_has_veic) {
151 set_vi_handler(MSC01E_INT_PERFCTR, mips_perf_dispatch);
152 mips_cpu_perf_irq = MSC01E_INT_BASE + MSC01E_INT_PERFCTR;
153 } else if (mips_gic_present()) {
154 mips_cpu_perf_irq = gic_get_c0_perfcount_int();
155 } else if (cp0_perfcount_irq >= 0) {
156 mips_cpu_perf_irq = MIPS_CPU_IRQ_BASE + cp0_perfcount_irq;
157 } else {
158 mips_cpu_perf_irq = -1;
159 }
160
161 return mips_cpu_perf_irq;
162}
163EXPORT_SYMBOL_GPL(get_c0_perfcount_int);
164
165unsigned int get_c0_compare_int(void)
166{
167 if (cpu_has_veic) {
168 set_vi_handler(MSC01E_INT_CPUCTR, mips_timer_dispatch);
169 mips_cpu_timer_irq = MSC01E_INT_BASE + MSC01E_INT_CPUCTR;
170 } else if (mips_gic_present()) {
171 mips_cpu_timer_irq = gic_get_c0_compare_int();
172 } else {
173 mips_cpu_timer_irq = MIPS_CPU_IRQ_BASE + cp0_compare_irq;
174 }
175
176 return mips_cpu_timer_irq;
177}
178
179static void __init init_rtc(void)
180{
181 unsigned char freq, ctrl;
182
183 /* Set 32KHz time base if not already set */
184 freq = CMOS_READ(RTC_FREQ_SELECT);
185 if ((freq & RTC_DIV_CTL) != RTC_REF_CLCK_32KHZ)
186 CMOS_WRITE(RTC_REF_CLCK_32KHZ, RTC_FREQ_SELECT);
187
188 /* Ensure SET bit is clear so RTC can run */
189 ctrl = CMOS_READ(RTC_CONTROL);
190 if (ctrl & RTC_SET)
191 CMOS_WRITE(ctrl & ~RTC_SET, RTC_CONTROL);
192}
193
194#ifdef CONFIG_CLKSRC_MIPS_GIC
195static u32 gic_frequency_dt;
196
197static struct property gic_frequency_prop = {
198 .name = "clock-frequency",
199 .length = sizeof(u32),
200 .value = &gic_frequency_dt,
201};
202
203static void update_gic_frequency_dt(void)
204{
205 struct device_node *node;
206
207 gic_frequency_dt = cpu_to_be32(gic_frequency);
208
209 node = of_find_compatible_node(NULL, NULL, "mti,gic-timer");
210 if (!node) {
211 pr_err("mti,gic-timer device node not found\n");
212 return;
213 }
214
215 if (of_update_property(node, &gic_frequency_prop) < 0)
216 pr_err("error updating gic frequency property\n");
217
218 of_node_put(node);
219}
220
221#endif
222
223void __init plat_time_init(void)
224{
225 unsigned int prid = read_c0_prid() & (PRID_COMP_MASK | PRID_IMP_MASK);
226 unsigned int freq;
227
228 init_rtc();
229 estimate_frequencies();
230
231 freq = mips_hpt_frequency;
232 if ((prid != (PRID_COMP_MIPS | PRID_IMP_20KC)) &&
233 (prid != (PRID_COMP_MIPS | PRID_IMP_25KF)))
234 freq *= 2;
235 freq = freqround(freq, amount: 5000);
236 printk("CPU frequency %d.%02d MHz\n", freq/1000000,
237 (freq%1000000)*100/1000000);
238
239#ifdef CONFIG_I8253
240 /* Only Malta has a PIT. */
241 setup_pit_timer();
242#endif
243
244 if (mips_gic_present()) {
245 freq = freqround(freq: gic_frequency, amount: 5000);
246 printk("GIC frequency %d.%02d MHz\n", freq/1000000,
247 (freq%1000000)*100/1000000);
248#ifdef CONFIG_CLKSRC_MIPS_GIC
249 update_gic_frequency_dt();
250 timer_probe();
251#endif
252 }
253}
254

source code of linux/arch/mips/mti-malta/malta-time.c