aboutsummaryrefslogtreecommitdiffstats
path: root/arch/cris/arch-v32/kernel/time.c
blob: b1920d8de403acbcdac0c5ab0a3248acfd93748f (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
/*
 *  linux/arch/cris/arch-v32/kernel/time.c
 *
 *  Copyright (C) 2003-2007 Axis Communications AB
 *
 */

#include <linux/timex.h>
#include <linux/time.h>
#include <linux/jiffies.h>
#include <linux/interrupt.h>
#include <linux/swap.h>
#include <linux/sched.h>
#include <linux/init.h>
#include <linux/threads.h>
#include <linux/cpufreq.h>
#include <asm/types.h>
#include <asm/signal.h>
#include <asm/io.h>
#include <asm/delay.h>
#include <asm/rtc.h>
#include <asm/irq.h>
#include <asm/irq_regs.h>

#include <hwregs/reg_map.h>
#include <hwregs/reg_rdwr.h>
#include <hwregs/timer_defs.h>
#include <hwregs/intr_vect_defs.h>
#ifdef CONFIG_CRIS_MACH_ARTPEC3
#include <hwregs/clkgen_defs.h>
#endif

/* Watchdog defines */
#define ETRAX_WD_KEY_MASK	0x7F /* key is 7 bit */
#define ETRAX_WD_HZ		763 /* watchdog counts at 763 Hz */
/* Number of 763 counts before watchdog bites */
#define ETRAX_WD_CNT		((2*ETRAX_WD_HZ)/HZ + 1)

unsigned long timer_regs[NR_CPUS] =
{
	regi_timer0,
#ifdef CONFIG_SMP
	regi_timer2
#endif
};

extern void update_xtime_from_cmos(void);
extern int set_rtc_mmss(unsigned long nowtime);
extern int have_rtc;

#ifdef CONFIG_CPU_FREQ
static int
cris_time_freq_notifier(struct notifier_block *nb, unsigned long val,
			void *data);

static struct notifier_block cris_time_freq_notifier_block = {
	.notifier_call = cris_time_freq_notifier,
};
#endif

unsigned long get_ns_in_jiffie(void)
{
	reg_timer_r_tmr0_data data;
	unsigned long ns;

	data = REG_RD(timer, regi_timer0, r_tmr0_data);
	ns = (TIMER0_DIV - data) * 10;
	return ns;
}

unsigned long do_slow_gettimeoffset(void)
{
	unsigned long count;
	unsigned long usec_count = 0;

	/* For the first call after boot */
	static unsigned long count_p = TIMER0_DIV;
	static unsigned long jiffies_p = 0;

	/* Cache volatile jiffies temporarily; we have IRQs turned off. */
	unsigned long jiffies_t;

	/* The timer interrupt comes from Etrax timer 0. In order to get
	 * better precision, we check the current value. It might have
	 * underflowed already though. */
	count = REG_RD(timer, regi_timer0, r_tmr0_data);
	jiffies_t = jiffies;

	/* Avoiding timer inconsistencies (they are rare, but they happen)
	 * There is one problem that must be avoided here:
	 *	1. the timer counter underflows
	 */
	if( jiffies_t == jiffies_p ) {
		if( count > count_p ) {
			/* Timer wrapped, use new count and prescale.
			 * Increase the time corresponding to one jiffy.
			 */
			usec_count = 1000000/HZ;
		}
	} else
		jiffies_p = jiffies_t;
        count_p = count;
	/* Convert timer value to usec */
	/* 100 MHz timer, divide by 100 to get usec */
	usec_count +=  (TIMER0_DIV - count) / 100;
	return usec_count;
}

/* From timer MDS describing the hardware watchdog:
 * 4.3.1 Watchdog Operation
 * The watchdog timer is an 8-bit timer with a configurable start value.
 * Once started the watchdog counts downwards with a frequency of 763 Hz
 * (100/131072 MHz). When the watchdog counts down to 1, it generates an
 * NMI (Non Maskable Interrupt), and when it counts down to 0, it resets the
 * chip.
 */
/* This gives us 1.3 ms to do something useful when the NMI comes */

/* Right now, starting the watchdog is the same as resetting it */
#define start_watchdog reset_watchdog

#if defined(CONFIG_ETRAX_WATCHDOG)
static short int watchdog_key = 42;  /* arbitrary 7 bit number */
#endif

/* Number of pages to consider "out of memory". It is normal that the memory
 * is used though, so set this really low. */
#define WATCHDOG_MIN_FREE_PAGES 8

void
reset_watchdog(void)
{
#if defined(CONFIG_ETRAX_WATCHDOG)
	reg_timer_rw_wd_ctrl wd_ctrl = { 0 };

	/* Only keep watchdog happy as long as we have memory left! */
	if(nr_free_pages() > WATCHDOG_MIN_FREE_PAGES) {
		/* Reset the watchdog with the inverse of the old key */
		/* Invert key, which is 7 bits */
		watchdog_key ^= ETRAX_WD_KEY_MASK;
		wd_ctrl.cnt = ETRAX_WD_CNT;
		wd_ctrl.cmd = regk_timer_start;
		wd_ctrl.key = watchdog_key;
		REG_WR(timer, regi_timer0, rw_wd_ctrl, wd_ctrl);
	}
#endif
}

/* stop the watchdog - we still need the correct key */

void
stop_watchdog(void)
{
#if defined(CONFIG_ETRAX_WATCHDOG)
	reg_timer_rw_wd_ctrl wd_ctrl = { 0 };
	watchdog_key ^= ETRAX_WD_KEY_MASK; /* invert key, which is 7 bits */
	wd_ctrl.cnt = ETRAX_WD_CNT;
	wd_ctrl.cmd = regk_timer_stop;
	wd_ctrl.key = watchdog_key;
	REG_WR(timer, regi_timer0, rw_wd_ctrl, wd_ctrl);
#endif
}

extern void show_registers(struct pt_regs *regs);

void
handle_watchdog_bite(struct pt_regs* regs)
{
#if defined(CONFIG_ETRAX_WATCHDOG)
	extern int cause_of_death;

	oops_in_progress = 1;
	printk(KERN_WARNING "Watchdog bite\n");

	/* Check if forced restart or unexpected watchdog */
	if (cause_of_death == 0xbedead) {
#ifdef CONFIG_CRIS_MACH_ARTPEC3
		/* There is a bug in Artpec-3 (voodoo TR 78) that requires
		 * us to go to lower frequency for the reset to be reliable
		 */
		reg_clkgen_rw_clk_ctrl ctrl =
			REG_RD(clkgen, regi_clkgen, rw_clk_ctrl);
		ctrl.pll = 0;
		REG_WR(clkgen, regi_clkgen, rw_clk_ctrl, ctrl);
#endif
		while(1);
	}

	/* Unexpected watchdog, stop the watchdog and dump registers. */
	stop_watchdog();
	printk(KERN_WARNING "Oops: bitten by watchdog\n");
	show_registers(regs);
	oops_in_progress = 0;
#ifndef CONFIG_ETRAX_WATCHDOG_NICE_DOGGY
	reset_watchdog();
#endif
	while(1) /* nothing */;
#endif
}

/* Last time the cmos clock got updated. */
static long last_rtc_update = 0;

/*
 * timer_interrupt() needs to keep up the real-time clock,
 * as well as call the "do_timer()" routine every clocktick.
 */
extern void cris_do_profile(struct pt_regs *regs);

static inline irqreturn_t
timer_interrupt(int irq, void *dev_id)
{
	struct pt_regs *regs = get_irq_regs();
	int cpu = smp_processor_id();
	reg_timer_r_masked_intr masked_intr;
	reg_timer_rw_ack_intr ack_intr = { 0 };

	/* Check if the timer interrupt is for us (a tmr0 int) */
	masked_intr = REG_RD(timer, timer_regs[cpu], r_masked_intr);
	if (!masked_intr.tmr0)
		return IRQ_NONE;

	/* Acknowledge the timer irq. */
	ack_intr.tmr0 = 1;
	REG_WR(timer, timer_regs[cpu], rw_ack_intr, ack_intr);

	/* Reset watchdog otherwise it resets us! */
	reset_watchdog();

        /* Update statistics. */
	update_process_times(user_mode(regs));

	cris_do_profile(regs); /* Save profiling information */

	/* The master CPU is responsible for the time keeping. */
	if (cpu != 0)
		return IRQ_HANDLED;

	/* Call the real timer interrupt handler */
	do_timer(1);

	/*
	 * If we have an externally synchronized Linux clock, then update
	 * CMOS clock accordingly every ~11 minutes. Set_rtc_mmss() has to be
	 * called as close as possible to 500 ms before the new second starts.
	 *
	 * The division here is not time critical since it will run once in
	 * 11 minutes
	 */
	if ((time_status & STA_UNSYNC) == 0 &&
	    xtime.tv_sec > last_rtc_update + 660 &&
	    (xtime.tv_nsec / 1000) >= 500000 - (tick_nsec / 1000) / 2 &&
	    (xtime.tv_nsec / 1000) <= 500000 + (tick_nsec / 1000) / 2) {
		if (set_rtc_mmss(xtime.tv_sec) == 0)
			last_rtc_update = xtime.tv_sec;
		else
			/* Do it again in 60 s */
			last_rtc_update = xtime.tv_sec - 600;
	}
        return IRQ_HANDLED;
}

/* Timer is IRQF_SHARED so drivers can add stuff to the timer irq chain.
 * It needs to be IRQF_DISABLED to make the jiffies update work properly.
 */
static struct irqaction irq_timer = {
	.handler = timer_interrupt,
	.flags = IRQF_SHARED | IRQF_DISABLED,
	.name = "timer"
};

void __init
cris_timer_init(void)
{
	int cpu = smp_processor_id();
	reg_timer_rw_tmr0_ctrl tmr0_ctrl = { 0 };
	reg_timer_rw_tmr0_div tmr0_div = TIMER0_DIV;
	reg_timer_rw_intr_mask timer_intr_mask;

	/* Setup the etrax timers.
	 * Base frequency is 100MHz, divider 1000000 -> 100 HZ
	 * We use timer0, so timer1 is free.
	 * The trig timer is used by the fasttimer API if enabled.
	 */

	tmr0_ctrl.op = regk_timer_ld;
	tmr0_ctrl.freq = regk_timer_f100;
	REG_WR(timer, timer_regs[cpu], rw_tmr0_div, tmr0_div);
	REG_WR(timer, timer_regs[cpu], rw_tmr0_ctrl, tmr0_ctrl); /* Load */
	tmr0_ctrl.op = regk_timer_run;
	REG_WR(timer, timer_regs[cpu], rw_tmr0_ctrl, tmr0_ctrl); /* Start */

	/* Enable the timer irq. */
	timer_intr_mask = REG_RD(timer, timer_regs[cpu], rw_intr_mask);
	timer_intr_mask.tmr0 = 1;
	REG_WR(timer, timer_regs[cpu], rw_intr_mask, timer_intr_mask);
}

void __init
time_init(void)
{
	reg_intr_vect_rw_mask intr_mask;

	/* Probe for the RTC and read it if it exists.
	 * Before the RTC can be probed the loops_per_usec variable needs
	 * to be initialized to make usleep work. A better value for
	 * loops_per_usec is calculated by the kernel later once the
	 * clock has started.
	 */
	loops_per_usec = 50;

	if(RTC_INIT() < 0) {
		/* No RTC, start at 1980 */
		xtime.tv_sec = 0;
		xtime.tv_nsec = 0;
		have_rtc = 0;
	} else {
		/* Get the current time */
		have_rtc = 1;
		update_xtime_from_cmos();
	}

	/*
	 * Initialize wall_to_monotonic such that adding it to
	 * xtime will yield zero, the tv_nsec field must be normalized
	 * (i.e., 0 <= nsec < NSEC_PER_SEC).
	 */
	set_normalized_timespec(&wall_to_monotonic, -xtime.tv_sec, -xtime.tv_nsec);

	/* Start CPU local timer. */
	cris_timer_init();

	/* Enable the timer irq in global config. */
	intr_mask = REG_RD_VECT(intr_vect, regi_irq, rw_mask, 1);
	intr_mask.timer0 = 1;
	REG_WR_VECT(intr_vect, regi_irq, rw_mask, 1, intr_mask);

	/* Now actually register the timer irq handler that calls
	 * timer_interrupt(). */
	setup_irq(TIMER0_INTR_VECT, &irq_timer);

	/* Enable watchdog if we should use one. */

#if defined(CONFIG_ETRAX_WATCHDOG)
	printk(KERN_INFO "Enabling watchdog...\n");
	start_watchdog();

	/* If we use the hardware watchdog, we want to trap it as an NMI
	 * and dump registers before it resets us.  For this to happen, we
	 * must set the "m" NMI enable flag (which once set, is unset only
	 * when an NMI is taken). */
	{
		unsigned long flags;
		local_save_flags(flags);
		flags |= (1<<30); /* NMI M flag is at bit 30 */
		local_irq_restore(flags);
	}
#endif

#ifdef CONFIG_CPU_FREQ
	cpufreq_register_notifier(&cris_time_freq_notifier_block,
		CPUFREQ_TRANSITION_NOTIFIER);
#endif
}

#ifdef CONFIG_CPU_FREQ
static int
cris_time_freq_notifier(struct notifier_block *nb, unsigned long val,
			void *data)
{
	struct cpufreq_freqs *freqs = data;
	if (val == CPUFREQ_POSTCHANGE) {
		reg_timer_r_tmr0_data data;
		reg_timer_rw_tmr0_div div = (freqs->new * 500) / HZ;
		do {
			data = REG_RD(timer, timer_regs[freqs->cpu],
				r_tmr0_data);
		} while (data > 20);
		REG_WR(timer, timer_regs[freqs->cpu], rw_tmr0_div, div);
	}
	return 0;
}
#endif