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1/*
2 * OpenRISC time.c
3 *
4 * Linux architectural port borrowing liberally from similar works of
5 * others. All original copyrights apply as per the original source
6 * declaration.
7 *
8 * Modifications for the OpenRISC architecture:
9 * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
10 *
11 * This program is free software; you can redistribute it and/or
12 * modify it under the terms of the GNU General Public License
13 * as published by the Free Software Foundation; either version
14 * 2 of the License, or (at your option) any later version.
15 */
16
17#include <linux/kernel.h>
18#include <linux/time.h>
19#include <linux/timex.h>
20#include <linux/interrupt.h>
21#include <linux/ftrace.h>
22
23#include <linux/clocksource.h>
24#include <linux/clockchips.h>
25#include <linux/irq.h>
26#include <linux/io.h>
27
28#include <asm/cpuinfo.h>
29
30static int openrisc_timer_set_next_event(unsigned long delta,
31 struct clock_event_device *dev)
32{
33 u32 c;
34
35 /* Read 32-bit counter value, add delta, mask off the low 28 bits.
36 * We're guaranteed delta won't be bigger than 28 bits because the
37 * generic timekeeping code ensures that for us.
38 */
39 c = mfspr(SPR_TTCR);
40 c += delta;
41 c &= SPR_TTMR_TP;
42
43 /* Set counter and enable interrupt.
44 * Keep timer in continuous mode always.
45 */
46 mtspr(SPR_TTMR, SPR_TTMR_CR | SPR_TTMR_IE | c);
47
48 return 0;
49}
50
51static void openrisc_timer_set_mode(enum clock_event_mode mode,
52 struct clock_event_device *evt)
53{
54 switch (mode) {
55 case CLOCK_EVT_MODE_PERIODIC:
56 pr_debug(KERN_INFO "%s: periodic\n", __func__);
57 BUG();
58 break;
59 case CLOCK_EVT_MODE_ONESHOT:
60 pr_debug(KERN_INFO "%s: oneshot\n", __func__);
61 break;
62 case CLOCK_EVT_MODE_UNUSED:
63 pr_debug(KERN_INFO "%s: unused\n", __func__);
64 break;
65 case CLOCK_EVT_MODE_SHUTDOWN:
66 pr_debug(KERN_INFO "%s: shutdown\n", __func__);
67 break;
68 case CLOCK_EVT_MODE_RESUME:
69 pr_debug(KERN_INFO "%s: resume\n", __func__);
70 break;
71 }
72}
73
74/* This is the clock event device based on the OR1K tick timer.
75 * As the timer is being used as a continuous clock-source (required for HR
76 * timers) we cannot enable the PERIODIC feature. The tick timer can run using
77 * one-shot events, so no problem.
78 */
79
80static struct clock_event_device clockevent_openrisc_timer = {
81 .name = "openrisc_timer_clockevent",
82 .features = CLOCK_EVT_FEAT_ONESHOT,
83 .rating = 300,
84 .set_next_event = openrisc_timer_set_next_event,
85 .set_mode = openrisc_timer_set_mode,
86};
87
88static inline void timer_ack(void)
89{
90 /* Clear the IP bit and disable further interrupts */
91 /* This can be done very simply... we just need to keep the timer
92 running, so just maintain the CR bits while clearing the rest
93 of the register
94 */
95 mtspr(SPR_TTMR, SPR_TTMR_CR);
96}
97
98/*
99 * The timer interrupt is mostly handled in generic code nowadays... this
100 * function just acknowledges the interrupt and fires the event handler that
101 * has been set on the clockevent device by the generic time management code.
102 *
103 * This function needs to be called by the timer exception handler and that's
104 * all the exception handler needs to do.
105 */
106
107irqreturn_t __irq_entry timer_interrupt(struct pt_regs *regs)
108{
109 struct pt_regs *old_regs = set_irq_regs(regs);
110 struct clock_event_device *evt = &clockevent_openrisc_timer;
111
112 timer_ack();
113
114 /*
115 * update_process_times() expects us to have called irq_enter().
116 */
117 irq_enter();
118 evt->event_handler(evt);
119 irq_exit();
120
121 set_irq_regs(old_regs);
122
123 return IRQ_HANDLED;
124}
125
126static __init void openrisc_clockevent_init(void)
127{
128 clockevents_calc_mult_shift(&clockevent_openrisc_timer,
129 cpuinfo.clock_frequency, 4);
130
131 /* We only have 28 bits */
132 clockevent_openrisc_timer.max_delta_ns =
133 clockevent_delta2ns((u32) 0x0fffffff, &clockevent_openrisc_timer);
134 clockevent_openrisc_timer.min_delta_ns =
135 clockevent_delta2ns(1, &clockevent_openrisc_timer);
136 clockevent_openrisc_timer.cpumask = cpumask_of(0);
137 clockevents_register_device(&clockevent_openrisc_timer);
138}
139
140/**
141 * Clocksource: Based on OpenRISC timer/counter
142 *
143 * This sets up the OpenRISC Tick Timer as a clock source. The tick timer
144 * is 32 bits wide and runs at the CPU clock frequency.
145 */
146
147static cycle_t openrisc_timer_read(struct clocksource *cs)
148{
149 return (cycle_t) mfspr(SPR_TTCR);
150}
151
152static struct clocksource openrisc_timer = {
153 .name = "openrisc_timer",
154 .rating = 200,
155 .read = openrisc_timer_read,
156 .mask = CLOCKSOURCE_MASK(32),
157 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
158};
159
160static int __init openrisc_timer_init(void)
161{
162 if (clocksource_register_hz(&openrisc_timer, cpuinfo.clock_frequency))
163 panic("failed to register clocksource");
164
165 /* Enable the incrementer: 'continuous' mode with interrupt disabled */
166 mtspr(SPR_TTMR, SPR_TTMR_CR);
167
168 return 0;
169}
170
171void __init time_init(void)
172{
173 u32 upr;
174
175 upr = mfspr(SPR_UPR);
176 if (!(upr & SPR_UPR_TTP))
177 panic("Linux not supported on devices without tick timer");
178
179 openrisc_timer_init();
180 openrisc_clockevent_init();
181}
1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * OpenRISC time.c
4 *
5 * Linux architectural port borrowing liberally from similar works of
6 * others. All original copyrights apply as per the original source
7 * declaration.
8 *
9 * Modifications for the OpenRISC architecture:
10 * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
11 */
12
13#include <linux/kernel.h>
14#include <linux/time.h>
15#include <linux/timex.h>
16#include <linux/interrupt.h>
17#include <linux/ftrace.h>
18
19#include <linux/clocksource.h>
20#include <linux/clockchips.h>
21#include <linux/irq.h>
22#include <linux/io.h>
23#include <linux/of_clk.h>
24
25#include <asm/cpuinfo.h>
26#include <asm/time.h>
27
28irqreturn_t __irq_entry timer_interrupt(struct pt_regs *regs);
29
30/* Test the timer ticks to count, used in sync routine */
31inline void openrisc_timer_set(unsigned long count)
32{
33 mtspr(SPR_TTCR, count);
34}
35
36/* Set the timer to trigger in delta cycles */
37inline void openrisc_timer_set_next(unsigned long delta)
38{
39 u32 c;
40
41 /* Read 32-bit counter value, add delta, mask off the low 28 bits.
42 * We're guaranteed delta won't be bigger than 28 bits because the
43 * generic timekeeping code ensures that for us.
44 */
45 c = mfspr(SPR_TTCR);
46 c += delta;
47 c &= SPR_TTMR_TP;
48
49 /* Set counter and enable interrupt.
50 * Keep timer in continuous mode always.
51 */
52 mtspr(SPR_TTMR, SPR_TTMR_CR | SPR_TTMR_IE | c);
53}
54
55static int openrisc_timer_set_next_event(unsigned long delta,
56 struct clock_event_device *dev)
57{
58 openrisc_timer_set_next(delta);
59 return 0;
60}
61
62/* This is the clock event device based on the OR1K tick timer.
63 * As the timer is being used as a continuous clock-source (required for HR
64 * timers) we cannot enable the PERIODIC feature. The tick timer can run using
65 * one-shot events, so no problem.
66 */
67static DEFINE_PER_CPU(struct clock_event_device, clockevent_openrisc_timer);
68
69void openrisc_clockevent_init(void)
70{
71 unsigned int cpu = smp_processor_id();
72 struct clock_event_device *evt =
73 &per_cpu(clockevent_openrisc_timer, cpu);
74 struct cpuinfo_or1k *cpuinfo = &cpuinfo_or1k[cpu];
75
76 mtspr(SPR_TTMR, SPR_TTMR_CR);
77
78#ifdef CONFIG_SMP
79 evt->broadcast = tick_broadcast;
80#endif
81 evt->name = "openrisc_timer_clockevent",
82 evt->features = CLOCK_EVT_FEAT_ONESHOT,
83 evt->rating = 300,
84 evt->set_next_event = openrisc_timer_set_next_event,
85
86 evt->cpumask = cpumask_of(cpu);
87
88 /* We only have 28 bits */
89 clockevents_config_and_register(evt, cpuinfo->clock_frequency,
90 100, 0x0fffffff);
91
92}
93
94static inline void timer_ack(void)
95{
96 /* Clear the IP bit and disable further interrupts */
97 /* This can be done very simply... we just need to keep the timer
98 running, so just maintain the CR bits while clearing the rest
99 of the register
100 */
101 mtspr(SPR_TTMR, SPR_TTMR_CR);
102}
103
104/*
105 * The timer interrupt is mostly handled in generic code nowadays... this
106 * function just acknowledges the interrupt and fires the event handler that
107 * has been set on the clockevent device by the generic time management code.
108 *
109 * This function needs to be called by the timer exception handler and that's
110 * all the exception handler needs to do.
111 */
112
113irqreturn_t __irq_entry timer_interrupt(struct pt_regs *regs)
114{
115 struct pt_regs *old_regs = set_irq_regs(regs);
116 unsigned int cpu = smp_processor_id();
117 struct clock_event_device *evt =
118 &per_cpu(clockevent_openrisc_timer, cpu);
119
120 timer_ack();
121
122 /*
123 * update_process_times() expects us to have called irq_enter().
124 */
125 irq_enter();
126 evt->event_handler(evt);
127 irq_exit();
128
129 set_irq_regs(old_regs);
130
131 return IRQ_HANDLED;
132}
133
134/*
135 * Clocksource: Based on OpenRISC timer/counter
136 *
137 * This sets up the OpenRISC Tick Timer as a clock source. The tick timer
138 * is 32 bits wide and runs at the CPU clock frequency.
139 */
140static u64 openrisc_timer_read(struct clocksource *cs)
141{
142 return (u64) mfspr(SPR_TTCR);
143}
144
145static struct clocksource openrisc_timer = {
146 .name = "openrisc_timer",
147 .rating = 200,
148 .read = openrisc_timer_read,
149 .mask = CLOCKSOURCE_MASK(32),
150 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
151};
152
153static int __init openrisc_timer_init(void)
154{
155 struct cpuinfo_or1k *cpuinfo = &cpuinfo_or1k[smp_processor_id()];
156
157 if (clocksource_register_hz(&openrisc_timer, cpuinfo->clock_frequency))
158 panic("failed to register clocksource");
159
160 /* Enable the incrementer: 'continuous' mode with interrupt disabled */
161 mtspr(SPR_TTMR, SPR_TTMR_CR);
162
163 return 0;
164}
165
166void __init time_init(void)
167{
168 u32 upr;
169
170 upr = mfspr(SPR_UPR);
171 if (!(upr & SPR_UPR_TTP))
172 panic("Linux not supported on devices without tick timer");
173
174 openrisc_timer_init();
175 openrisc_clockevent_init();
176
177 of_clk_init(NULL);
178 timer_probe();
179}