xref: /openbmc/linux/arch/loongarch/kernel/time.c (revision f4356947)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Common time service routines for LoongArch machines.
4  *
5  * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
6  */
7 #include <linux/clockchips.h>
8 #include <linux/delay.h>
9 #include <linux/export.h>
10 #include <linux/init.h>
11 #include <linux/interrupt.h>
12 #include <linux/kernel.h>
13 #include <linux/sched_clock.h>
14 #include <linux/spinlock.h>
15 
16 #include <asm/cpu-features.h>
17 #include <asm/loongarch.h>
18 #include <asm/time.h>
19 
20 u64 cpu_clock_freq;
21 EXPORT_SYMBOL(cpu_clock_freq);
22 u64 const_clock_freq;
23 EXPORT_SYMBOL(const_clock_freq);
24 
25 static DEFINE_RAW_SPINLOCK(state_lock);
26 static DEFINE_PER_CPU(struct clock_event_device, constant_clockevent_device);
27 
28 static void constant_event_handler(struct clock_event_device *dev)
29 {
30 }
31 
32 irqreturn_t constant_timer_interrupt(int irq, void *data)
33 {
34 	int cpu = smp_processor_id();
35 	struct clock_event_device *cd;
36 
37 	/* Clear Timer Interrupt */
38 	write_csr_tintclear(CSR_TINTCLR_TI);
39 	cd = &per_cpu(constant_clockevent_device, cpu);
40 	cd->event_handler(cd);
41 
42 	return IRQ_HANDLED;
43 }
44 
45 static int constant_set_state_oneshot(struct clock_event_device *evt)
46 {
47 	unsigned long timer_config;
48 
49 	raw_spin_lock(&state_lock);
50 
51 	timer_config = csr_read64(LOONGARCH_CSR_TCFG);
52 	timer_config |= CSR_TCFG_EN;
53 	timer_config &= ~CSR_TCFG_PERIOD;
54 	csr_write64(timer_config, LOONGARCH_CSR_TCFG);
55 
56 	raw_spin_unlock(&state_lock);
57 
58 	return 0;
59 }
60 
61 static int constant_set_state_oneshot_stopped(struct clock_event_device *evt)
62 {
63 	unsigned long timer_config;
64 
65 	raw_spin_lock(&state_lock);
66 
67 	timer_config = csr_read64(LOONGARCH_CSR_TCFG);
68 	timer_config &= ~CSR_TCFG_EN;
69 	csr_write64(timer_config, LOONGARCH_CSR_TCFG);
70 
71 	raw_spin_unlock(&state_lock);
72 
73 	return 0;
74 }
75 
76 static int constant_set_state_periodic(struct clock_event_device *evt)
77 {
78 	unsigned long period;
79 	unsigned long timer_config;
80 
81 	raw_spin_lock(&state_lock);
82 
83 	period = const_clock_freq / HZ;
84 	timer_config = period & CSR_TCFG_VAL;
85 	timer_config |= (CSR_TCFG_PERIOD | CSR_TCFG_EN);
86 	csr_write64(timer_config, LOONGARCH_CSR_TCFG);
87 
88 	raw_spin_unlock(&state_lock);
89 
90 	return 0;
91 }
92 
93 static int constant_set_state_shutdown(struct clock_event_device *evt)
94 {
95 	return 0;
96 }
97 
98 static int constant_timer_next_event(unsigned long delta, struct clock_event_device *evt)
99 {
100 	unsigned long timer_config;
101 
102 	delta &= CSR_TCFG_VAL;
103 	timer_config = delta | CSR_TCFG_EN;
104 	csr_write64(timer_config, LOONGARCH_CSR_TCFG);
105 
106 	return 0;
107 }
108 
109 static unsigned long __init get_loops_per_jiffy(void)
110 {
111 	unsigned long lpj = (unsigned long)const_clock_freq;
112 
113 	do_div(lpj, HZ);
114 
115 	return lpj;
116 }
117 
118 static long init_offset __nosavedata;
119 
120 void save_counter(void)
121 {
122 	init_offset = drdtime();
123 }
124 
125 void sync_counter(void)
126 {
127 	/* Ensure counter begin at 0 */
128 	csr_write64(init_offset, LOONGARCH_CSR_CNTC);
129 }
130 
131 static int get_timer_irq(void)
132 {
133 	struct irq_domain *d = irq_find_matching_fwnode(cpuintc_handle, DOMAIN_BUS_ANY);
134 
135 	if (d)
136 		return irq_create_mapping(d, INT_TI);
137 
138 	return -EINVAL;
139 }
140 
141 int constant_clockevent_init(void)
142 {
143 	unsigned int cpu = smp_processor_id();
144 	unsigned long min_delta = 0x600;
145 	unsigned long max_delta = (1UL << 48) - 1;
146 	struct clock_event_device *cd;
147 	static int irq = 0, timer_irq_installed = 0;
148 
149 	if (!timer_irq_installed) {
150 		irq = get_timer_irq();
151 		if (irq < 0)
152 			pr_err("Failed to map irq %d (timer)\n", irq);
153 	}
154 
155 	cd = &per_cpu(constant_clockevent_device, cpu);
156 
157 	cd->name = "Constant";
158 	cd->features = CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_PERCPU;
159 
160 	cd->irq = irq;
161 	cd->rating = 320;
162 	cd->cpumask = cpumask_of(cpu);
163 	cd->set_state_oneshot = constant_set_state_oneshot;
164 	cd->set_state_oneshot_stopped = constant_set_state_oneshot_stopped;
165 	cd->set_state_periodic = constant_set_state_periodic;
166 	cd->set_state_shutdown = constant_set_state_shutdown;
167 	cd->set_next_event = constant_timer_next_event;
168 	cd->event_handler = constant_event_handler;
169 
170 	clockevents_config_and_register(cd, const_clock_freq, min_delta, max_delta);
171 
172 	if (timer_irq_installed)
173 		return 0;
174 
175 	timer_irq_installed = 1;
176 
177 	sync_counter();
178 
179 	if (request_irq(irq, constant_timer_interrupt, IRQF_PERCPU | IRQF_TIMER, "timer", NULL))
180 		pr_err("Failed to request irq %d (timer)\n", irq);
181 
182 	lpj_fine = get_loops_per_jiffy();
183 	pr_info("Constant clock event device register\n");
184 
185 	return 0;
186 }
187 
188 static u64 read_const_counter(struct clocksource *clk)
189 {
190 	return drdtime();
191 }
192 
193 static u64 native_sched_clock(void)
194 {
195 	return read_const_counter(NULL);
196 }
197 
198 static struct clocksource clocksource_const = {
199 	.name = "Constant",
200 	.rating = 400,
201 	.read = read_const_counter,
202 	.mask = CLOCKSOURCE_MASK(64),
203 	.flags = CLOCK_SOURCE_IS_CONTINUOUS,
204 	.vdso_clock_mode = VDSO_CLOCKMODE_CPU,
205 };
206 
207 int __init constant_clocksource_init(void)
208 {
209 	int res;
210 	unsigned long freq = const_clock_freq;
211 
212 	res = clocksource_register_hz(&clocksource_const, freq);
213 
214 	sched_clock_register(native_sched_clock, 64, freq);
215 
216 	pr_info("Constant clock source device register\n");
217 
218 	return res;
219 }
220 
221 void __init time_init(void)
222 {
223 	if (!cpu_has_cpucfg)
224 		const_clock_freq = cpu_clock_freq;
225 	else
226 		const_clock_freq = calc_const_freq();
227 
228 	init_offset = -(drdtime() - csr_read64(LOONGARCH_CSR_CNTC));
229 
230 	constant_clockevent_init();
231 	constant_clocksource_init();
232 }
233