tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/*
2 * This file is subject to the terms and conditions of the GNU General Public
3 * License. See the file "COPYING" in the main directory of this archive
4 * for more details.
5 *
6 * Copyright (C) 2012 MIPS Technologies, Inc. All rights reserved.
7 */
8
9#define pr_fmt(fmt) "mips-gic-timer: " fmt
10
11#include <linux/clk.h>
12#include <linux/clockchips.h>
13#include <linux/cpu.h>
14#include <linux/init.h>
15#include <linux/interrupt.h>
16#include <linux/notifier.h>
17#include <linux/of_irq.h>
18#include <linux/percpu.h>
19#include <linux/smp.h>
20#include <linux/time.h>
21#include <asm/mips-cps.h>
22
23static DEFINE_PER_CPU(struct clock_event_device, gic_clockevent_device);
24static int gic_timer_irq;
25static unsigned int gic_frequency;
26
27static u64 notrace gic_read_count(void)
28{
29 unsigned int hi, hi2, lo;
30
31 if (mips_cm_is64)
32 return read_gic_counter();
33
34 do {
35 hi = read_gic_counter_32h();
36 lo = read_gic_counter_32l();
37 hi2 = read_gic_counter_32h();
38 } while (hi2 != hi);
39
40 return (((u64) hi) << 32) + lo;
41}
42
43static int gic_next_event(unsigned long delta, struct clock_event_device *evt)
44{
45 int cpu = cpumask_first(evt->cpumask);
46 u64 cnt;
47 int res;
48
49 cnt = gic_read_count();
50 cnt += (u64)delta;
51 if (cpu == raw_smp_processor_id()) {
52 write_gic_vl_compare(cnt);
53 } else {
54 write_gic_vl_other(mips_cm_vp_id(cpu));
55 write_gic_vo_compare(cnt);
56 }
57 res = ((int)(gic_read_count() - cnt) >= 0) ? -ETIME : 0;
58 return res;
59}
60
61static irqreturn_t gic_compare_interrupt(int irq, void *dev_id)
62{
63 struct clock_event_device *cd = dev_id;
64
65 write_gic_vl_compare(read_gic_vl_compare());
66 cd->event_handler(cd);
67 return IRQ_HANDLED;
68}
69
70static struct irqaction gic_compare_irqaction = {
71 .handler = gic_compare_interrupt,
72 .percpu_dev_id = &gic_clockevent_device,
73 .flags = IRQF_PERCPU | IRQF_TIMER,
74 .name = "timer",
75};
76
77static void gic_clockevent_cpu_init(unsigned int cpu,
78 struct clock_event_device *cd)
79{
80 cd->name = "MIPS GIC";
81 cd->features = CLOCK_EVT_FEAT_ONESHOT |
82 CLOCK_EVT_FEAT_C3STOP;
83
84 cd->rating = 350;
85 cd->irq = gic_timer_irq;
86 cd->cpumask = cpumask_of(cpu);
87 cd->set_next_event = gic_next_event;
88
89 clockevents_config_and_register(cd, gic_frequency, 0x300, 0x7fffffff);
90
91 enable_percpu_irq(gic_timer_irq, IRQ_TYPE_NONE);
92}
93
94static void gic_clockevent_cpu_exit(struct clock_event_device *cd)
95{
96 disable_percpu_irq(gic_timer_irq);
97}
98
99static void gic_update_frequency(void *data)
100{
101 unsigned long rate = (unsigned long)data;
102
103 clockevents_update_freq(this_cpu_ptr(&gic_clockevent_device), rate);
104}
105
106static int gic_starting_cpu(unsigned int cpu)
107{
108 gic_clockevent_cpu_init(cpu, this_cpu_ptr(&gic_clockevent_device));
109 return 0;
110}
111
112static int gic_clk_notifier(struct notifier_block *nb, unsigned long action,
113 void *data)
114{
115 struct clk_notifier_data *cnd = data;
116
117 if (action == POST_RATE_CHANGE)
118 on_each_cpu(gic_update_frequency, (void *)cnd->new_rate, 1);
119
120 return NOTIFY_OK;
121}
122
123static int gic_dying_cpu(unsigned int cpu)
124{
125 gic_clockevent_cpu_exit(this_cpu_ptr(&gic_clockevent_device));
126 return 0;
127}
128
129static struct notifier_block gic_clk_nb = {
130 .notifier_call = gic_clk_notifier,
131};
132
133static int gic_clockevent_init(void)
134{
135 int ret;
136
137 if (!gic_frequency)
138 return -ENXIO;
139
140 ret = setup_percpu_irq(gic_timer_irq, &gic_compare_irqaction);
141 if (ret < 0) {
142 pr_err("IRQ %d setup failed (%d)\n", gic_timer_irq, ret);
143 return ret;
144 }
145
146 cpuhp_setup_state(CPUHP_AP_MIPS_GIC_TIMER_STARTING,
147 "clockevents/mips/gic/timer:starting",
148 gic_starting_cpu, gic_dying_cpu);
149 return 0;
150}
151
152static u64 gic_hpt_read(struct clocksource *cs)
153{
154 return gic_read_count();
155}
156
157static struct clocksource gic_clocksource = {
158 .name = "GIC",
159 .read = gic_hpt_read,
160 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
161 .archdata = { .vdso_clock_mode = VDSO_CLOCK_GIC },
162};
163
164static int __init __gic_clocksource_init(void)
165{
166 unsigned int count_width;
167 int ret;
168
169 /* Set clocksource mask. */
170 count_width = read_gic_config() & GIC_CONFIG_COUNTBITS;
171 count_width >>= __ffs(GIC_CONFIG_COUNTBITS);
172 count_width *= 4;
173 count_width += 32;
174 gic_clocksource.mask = CLOCKSOURCE_MASK(count_width);
175
176 /* Calculate a somewhat reasonable rating value. */
177 gic_clocksource.rating = 200 + gic_frequency / 10000000;
178
179 ret = clocksource_register_hz(&gic_clocksource, gic_frequency);
180 if (ret < 0)
181 pr_warn("Unable to register clocksource\n");
182
183 return ret;
184}
185
186static int __init gic_clocksource_of_init(struct device_node *node)
187{
188 struct clk *clk;
189 int ret;
190
191 if (!mips_gic_present() || !node->parent ||
192 !of_device_is_compatible(node->parent, "mti,gic")) {
193 pr_warn("No DT definition\n");
194 return -ENXIO;
195 }
196
197 clk = of_clk_get(node, 0);
198 if (!IS_ERR(clk)) {
199 ret = clk_prepare_enable(clk);
200 if (ret < 0) {
201 pr_err("Failed to enable clock\n");
202 clk_put(clk);
203 return ret;
204 }
205
206 gic_frequency = clk_get_rate(clk);
207 } else if (of_property_read_u32(node, "clock-frequency",
208 &gic_frequency)) {
209 pr_err("Frequency not specified\n");
210 return -EINVAL;
211 }
212 gic_timer_irq = irq_of_parse_and_map(node, 0);
213 if (!gic_timer_irq) {
214 pr_err("IRQ not specified\n");
215 return -EINVAL;
216 }
217
218 ret = __gic_clocksource_init();
219 if (ret)
220 return ret;
221
222 ret = gic_clockevent_init();
223 if (!ret && !IS_ERR(clk)) {
224 if (clk_notifier_register(clk, &gic_clk_nb) < 0)
225 pr_warn("Unable to register clock notifier\n");
226 }
227
228 /* And finally start the counter */
229 clear_gic_config(GIC_CONFIG_COUNTSTOP);
230
231 return 0;
232}
233TIMER_OF_DECLARE(mips_gic_timer, "mti,gic-timer",
234 gic_clocksource_of_init);