1 /*
2 * linux/arch/arm/kernel/smp_twd.c
3 *
4 * Copyright (C) 2002 ARM Ltd.
5 * All Rights Reserved
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
10 */
11 #include <linux/init.h>
12 #include <linux/kernel.h>
13 #include <linux/clk.h>
14 #include <linux/cpufreq.h>
15 #include <linux/delay.h>
16 #include <linux/device.h>
17 #include <linux/err.h>
18 #include <linux/smp.h>
19 #include <linux/jiffies.h>
20 #include <linux/clockchips.h>
21 #include <linux/interrupt.h>
22 #include <linux/io.h>
23 #include <linux/of_irq.h>
24 #include <linux/of_address.h>
25
26 #include <asm/smp_twd.h>
27 #include <asm/localtimer.h>
28 #include <asm/hardware/gic.h>
29
30 /* set up by the platform code */
31 static void __iomem *twd_base;
32
33 static struct clk *twd_clk;
34 static unsigned long twd_timer_rate;
35
36 static struct clock_event_device __percpu **twd_evt;
37 static int twd_ppi;
38
twd_set_mode(enum clock_event_mode mode,struct clock_event_device * clk)39 static void twd_set_mode(enum clock_event_mode mode,
40 struct clock_event_device *clk)
41 {
42 unsigned long ctrl;
43
44 switch (mode) {
45 case CLOCK_EVT_MODE_PERIODIC:
46 /* timer load already set up */
47 ctrl = TWD_TIMER_CONTROL_ENABLE | TWD_TIMER_CONTROL_IT_ENABLE
48 | TWD_TIMER_CONTROL_PERIODIC;
49 __raw_writel(twd_timer_rate / HZ, twd_base + TWD_TIMER_LOAD);
50 break;
51 case CLOCK_EVT_MODE_ONESHOT:
52 /* period set, and timer enabled in 'next_event' hook */
53 ctrl = TWD_TIMER_CONTROL_IT_ENABLE | TWD_TIMER_CONTROL_ONESHOT;
54 break;
55 case CLOCK_EVT_MODE_UNUSED:
56 case CLOCK_EVT_MODE_SHUTDOWN:
57 default:
58 ctrl = 0;
59 }
60
61 __raw_writel(ctrl, twd_base + TWD_TIMER_CONTROL);
62 }
63
twd_set_next_event(unsigned long evt,struct clock_event_device * unused)64 static int twd_set_next_event(unsigned long evt,
65 struct clock_event_device *unused)
66 {
67 unsigned long ctrl = __raw_readl(twd_base + TWD_TIMER_CONTROL);
68
69 ctrl |= TWD_TIMER_CONTROL_ENABLE;
70
71 __raw_writel(evt, twd_base + TWD_TIMER_COUNTER);
72 __raw_writel(ctrl, twd_base + TWD_TIMER_CONTROL);
73
74 return 0;
75 }
76
77 /*
78 * local_timer_ack: checks for a local timer interrupt.
79 *
80 * If a local timer interrupt has occurred, acknowledge and return 1.
81 * Otherwise, return 0.
82 */
twd_timer_ack(void)83 static int twd_timer_ack(void)
84 {
85 if (__raw_readl(twd_base + TWD_TIMER_INTSTAT)) {
86 __raw_writel(1, twd_base + TWD_TIMER_INTSTAT);
87 return 1;
88 }
89
90 return 0;
91 }
92
twd_timer_stop(struct clock_event_device * clk)93 static void twd_timer_stop(struct clock_event_device *clk)
94 {
95 twd_set_mode(CLOCK_EVT_MODE_UNUSED, clk);
96 disable_percpu_irq(clk->irq);
97 }
98
99 #ifdef CONFIG_CPU_FREQ
100
101 /*
102 * Updates clockevent frequency when the cpu frequency changes.
103 * Called on the cpu that is changing frequency with interrupts disabled.
104 */
twd_update_frequency(void * data)105 static void twd_update_frequency(void *data)
106 {
107 twd_timer_rate = clk_get_rate(twd_clk);
108
109 clockevents_update_freq(*__this_cpu_ptr(twd_evt), twd_timer_rate);
110 }
111
twd_cpufreq_transition(struct notifier_block * nb,unsigned long state,void * data)112 static int twd_cpufreq_transition(struct notifier_block *nb,
113 unsigned long state, void *data)
114 {
115 struct cpufreq_freqs *freqs = data;
116
117 /*
118 * The twd clock events must be reprogrammed to account for the new
119 * frequency. The timer is local to a cpu, so cross-call to the
120 * changing cpu.
121 */
122 if (state == CPUFREQ_POSTCHANGE || state == CPUFREQ_RESUMECHANGE)
123 smp_call_function_single(freqs->cpu, twd_update_frequency,
124 NULL, 1);
125
126 return NOTIFY_OK;
127 }
128
129 static struct notifier_block twd_cpufreq_nb = {
130 .notifier_call = twd_cpufreq_transition,
131 };
132
twd_cpufreq_init(void)133 static int twd_cpufreq_init(void)
134 {
135 if (twd_evt && *__this_cpu_ptr(twd_evt) && !IS_ERR(twd_clk))
136 return cpufreq_register_notifier(&twd_cpufreq_nb,
137 CPUFREQ_TRANSITION_NOTIFIER);
138
139 return 0;
140 }
141 core_initcall(twd_cpufreq_init);
142
143 #endif
144
twd_calibrate_rate(void)145 static void __cpuinit twd_calibrate_rate(void)
146 {
147 unsigned long count;
148 u64 waitjiffies;
149
150 /*
151 * If this is the first time round, we need to work out how fast
152 * the timer ticks
153 */
154 if (twd_timer_rate == 0) {
155 printk(KERN_INFO "Calibrating local timer... ");
156
157 /* Wait for a tick to start */
158 waitjiffies = get_jiffies_64() + 1;
159
160 while (get_jiffies_64() < waitjiffies)
161 udelay(10);
162
163 /* OK, now the tick has started, let's get the timer going */
164 waitjiffies += 5;
165
166 /* enable, no interrupt or reload */
167 __raw_writel(0x1, twd_base + TWD_TIMER_CONTROL);
168
169 /* maximum value */
170 __raw_writel(0xFFFFFFFFU, twd_base + TWD_TIMER_COUNTER);
171
172 while (get_jiffies_64() < waitjiffies)
173 udelay(10);
174
175 count = __raw_readl(twd_base + TWD_TIMER_COUNTER);
176
177 twd_timer_rate = (0xFFFFFFFFU - count) * (HZ / 5);
178
179 printk("%lu.%02luMHz.\n", twd_timer_rate / 1000000,
180 (twd_timer_rate / 10000) % 100);
181 }
182 }
183
twd_handler(int irq,void * dev_id)184 static irqreturn_t twd_handler(int irq, void *dev_id)
185 {
186 struct clock_event_device *evt = *(struct clock_event_device **)dev_id;
187
188 if (twd_timer_ack()) {
189 evt->event_handler(evt);
190 return IRQ_HANDLED;
191 }
192
193 return IRQ_NONE;
194 }
195
twd_get_clock(void)196 static struct clk *twd_get_clock(void)
197 {
198 struct clk *clk;
199 int err;
200
201 clk = clk_get_sys("smp_twd", NULL);
202 if (IS_ERR(clk)) {
203 pr_err("smp_twd: clock not found: %d\n", (int)PTR_ERR(clk));
204 return clk;
205 }
206
207 err = clk_prepare(clk);
208 if (err) {
209 pr_err("smp_twd: clock failed to prepare: %d\n", err);
210 clk_put(clk);
211 return ERR_PTR(err);
212 }
213
214 err = clk_enable(clk);
215 if (err) {
216 pr_err("smp_twd: clock failed to enable: %d\n", err);
217 clk_unprepare(clk);
218 clk_put(clk);
219 return ERR_PTR(err);
220 }
221
222 return clk;
223 }
224
225 /*
226 * Setup the local clock events for a CPU.
227 */
twd_timer_setup(struct clock_event_device * clk)228 static int __cpuinit twd_timer_setup(struct clock_event_device *clk)
229 {
230 struct clock_event_device **this_cpu_clk;
231
232 if (!twd_clk)
233 twd_clk = twd_get_clock();
234
235 if (!IS_ERR_OR_NULL(twd_clk))
236 twd_timer_rate = clk_get_rate(twd_clk);
237 else
238 twd_calibrate_rate();
239
240 __raw_writel(0, twd_base + TWD_TIMER_CONTROL);
241
242 clk->name = "local_timer";
243 clk->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT |
244 CLOCK_EVT_FEAT_C3STOP;
245 clk->rating = 350;
246 clk->set_mode = twd_set_mode;
247 clk->set_next_event = twd_set_next_event;
248 clk->irq = twd_ppi;
249
250 this_cpu_clk = __this_cpu_ptr(twd_evt);
251 *this_cpu_clk = clk;
252
253 clockevents_config_and_register(clk, twd_timer_rate,
254 0xf, 0xffffffff);
255 enable_percpu_irq(clk->irq, 0);
256
257 return 0;
258 }
259
260 static struct local_timer_ops twd_lt_ops __cpuinitdata = {
261 .setup = twd_timer_setup,
262 .stop = twd_timer_stop,
263 };
264
twd_local_timer_common_register(void)265 static int __init twd_local_timer_common_register(void)
266 {
267 int err;
268
269 twd_evt = alloc_percpu(struct clock_event_device *);
270 if (!twd_evt) {
271 err = -ENOMEM;
272 goto out_free;
273 }
274
275 err = request_percpu_irq(twd_ppi, twd_handler, "twd", twd_evt);
276 if (err) {
277 pr_err("twd: can't register interrupt %d (%d)\n", twd_ppi, err);
278 goto out_free;
279 }
280
281 err = local_timer_register(&twd_lt_ops);
282 if (err)
283 goto out_irq;
284
285 return 0;
286
287 out_irq:
288 free_percpu_irq(twd_ppi, twd_evt);
289 out_free:
290 iounmap(twd_base);
291 twd_base = NULL;
292 free_percpu(twd_evt);
293
294 return err;
295 }
296
twd_local_timer_register(struct twd_local_timer * tlt)297 int __init twd_local_timer_register(struct twd_local_timer *tlt)
298 {
299 if (twd_base || twd_evt)
300 return -EBUSY;
301
302 twd_ppi = tlt->res[1].start;
303
304 twd_base = ioremap(tlt->res[0].start, resource_size(&tlt->res[0]));
305 if (!twd_base)
306 return -ENOMEM;
307
308 return twd_local_timer_common_register();
309 }
310
311 #ifdef CONFIG_OF
312 const static struct of_device_id twd_of_match[] __initconst = {
313 { .compatible = "arm,cortex-a9-twd-timer", },
314 { .compatible = "arm,cortex-a5-twd-timer", },
315 { .compatible = "arm,arm11mp-twd-timer", },
316 { },
317 };
318
twd_local_timer_of_register(void)319 void __init twd_local_timer_of_register(void)
320 {
321 struct device_node *np;
322 int err;
323
324 np = of_find_matching_node(NULL, twd_of_match);
325 if (!np) {
326 err = -ENODEV;
327 goto out;
328 }
329
330 twd_ppi = irq_of_parse_and_map(np, 0);
331 if (!twd_ppi) {
332 err = -EINVAL;
333 goto out;
334 }
335
336 twd_base = of_iomap(np, 0);
337 if (!twd_base) {
338 err = -ENOMEM;
339 goto out;
340 }
341
342 err = twd_local_timer_common_register();
343
344 out:
345 WARN(err, "twd_local_timer_of_register failed (%d)\n", err);
346 }
347 #endif
348