xref: /openbmc/linux/arch/arm/kernel/smp_twd.c (revision 95e9fd10) 
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 
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 
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  */
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 
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  */
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 
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 
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 
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 
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 
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  */
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 
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 
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 
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