1/*
2 *  linux/arch/cris/arch-v32/kernel/time.c
3 *
4 *  Copyright (C) 2003-2010 Axis Communications AB
5 *
6 */
7
8#include <linux/timex.h>
9#include <linux/time.h>
10#include <linux/clocksource.h>
11#include <linux/clockchips.h>
12#include <linux/interrupt.h>
13#include <linux/swap.h>
14#include <linux/sched.h>
15#include <linux/init.h>
16#include <linux/threads.h>
17#include <linux/cpufreq.h>
18#include <linux/sched_clock.h>
19#include <linux/mm.h>
20#include <asm/types.h>
21#include <asm/signal.h>
22#include <asm/io.h>
23#include <asm/delay.h>
24#include <asm/irq.h>
25#include <asm/irq_regs.h>
26
27#include <hwregs/reg_map.h>
28#include <hwregs/reg_rdwr.h>
29#include <hwregs/timer_defs.h>
30#include <hwregs/intr_vect_defs.h>
31#ifdef CONFIG_CRIS_MACH_ARTPEC3
32#include <hwregs/clkgen_defs.h>
33#endif
34
35/* Watchdog defines */
36#define ETRAX_WD_KEY_MASK	0x7F /* key is 7 bit */
37#define ETRAX_WD_HZ		763 /* watchdog counts at 763 Hz */
38/* Number of 763 counts before watchdog bites */
39#define ETRAX_WD_CNT		((2*ETRAX_WD_HZ)/HZ + 1)
40
41#define CRISV32_TIMER_FREQ	(100000000lu)
42
43unsigned long timer_regs[NR_CPUS] =
44{
45	regi_timer0,
46};
47
48extern int set_rtc_mmss(unsigned long nowtime);
49
50#ifdef CONFIG_CPU_FREQ
51static int cris_time_freq_notifier(struct notifier_block *nb,
52				   unsigned long val, void *data);
53
54static struct notifier_block cris_time_freq_notifier_block = {
55	.notifier_call = cris_time_freq_notifier,
56};
57#endif
58
59unsigned long get_ns_in_jiffie(void)
60{
61	reg_timer_r_tmr0_data data;
62	unsigned long ns;
63
64	data = REG_RD(timer, regi_timer0, r_tmr0_data);
65	ns = (TIMER0_DIV - data) * 10;
66	return ns;
67}
68
69/* From timer MDS describing the hardware watchdog:
70 * 4.3.1 Watchdog Operation
71 * The watchdog timer is an 8-bit timer with a configurable start value.
72 * Once started the watchdog counts downwards with a frequency of 763 Hz
73 * (100/131072 MHz). When the watchdog counts down to 1, it generates an
74 * NMI (Non Maskable Interrupt), and when it counts down to 0, it resets the
75 * chip.
76 */
77/* This gives us 1.3 ms to do something useful when the NMI comes */
78
79/* Right now, starting the watchdog is the same as resetting it */
80#define start_watchdog reset_watchdog
81
82#if defined(CONFIG_ETRAX_WATCHDOG)
83static short int watchdog_key = 42;  /* arbitrary 7 bit number */
84#endif
85
86/* Number of pages to consider "out of memory". It is normal that the memory
87 * is used though, so set this really low. */
88#define WATCHDOG_MIN_FREE_PAGES 8
89
90#if defined(CONFIG_ETRAX_WATCHDOG_NICE_DOGGY)
91/* for reliable NICE_DOGGY behaviour */
92static int bite_in_progress;
93#endif
94
95void reset_watchdog(void)
96{
97#if defined(CONFIG_ETRAX_WATCHDOG)
98	reg_timer_rw_wd_ctrl wd_ctrl = { 0 };
99
100#if defined(CONFIG_ETRAX_WATCHDOG_NICE_DOGGY)
101	if (unlikely(bite_in_progress))
102		return;
103#endif
104	/* Only keep watchdog happy as long as we have memory left! */
105	if(nr_free_pages() > WATCHDOG_MIN_FREE_PAGES) {
106		/* Reset the watchdog with the inverse of the old key */
107		/* Invert key, which is 7 bits */
108		watchdog_key ^= ETRAX_WD_KEY_MASK;
109		wd_ctrl.cnt = ETRAX_WD_CNT;
110		wd_ctrl.cmd = regk_timer_start;
111		wd_ctrl.key = watchdog_key;
112		REG_WR(timer, regi_timer0, rw_wd_ctrl, wd_ctrl);
113	}
114#endif
115}
116
117/* stop the watchdog - we still need the correct key */
118
119void stop_watchdog(void)
120{
121#if defined(CONFIG_ETRAX_WATCHDOG)
122	reg_timer_rw_wd_ctrl wd_ctrl = { 0 };
123	watchdog_key ^= ETRAX_WD_KEY_MASK; /* invert key, which is 7 bits */
124	wd_ctrl.cnt = ETRAX_WD_CNT;
125	wd_ctrl.cmd = regk_timer_stop;
126	wd_ctrl.key = watchdog_key;
127	REG_WR(timer, regi_timer0, rw_wd_ctrl, wd_ctrl);
128#endif
129}
130
131extern void show_registers(struct pt_regs *regs);
132
133void handle_watchdog_bite(struct pt_regs *regs)
134{
135#if defined(CONFIG_ETRAX_WATCHDOG)
136	extern int cause_of_death;
137
138	nmi_enter();
139	oops_in_progress = 1;
140#if defined(CONFIG_ETRAX_WATCHDOG_NICE_DOGGY)
141	bite_in_progress = 1;
142#endif
143	printk(KERN_WARNING "Watchdog bite\n");
144
145	/* Check if forced restart or unexpected watchdog */
146	if (cause_of_death == 0xbedead) {
147#ifdef CONFIG_CRIS_MACH_ARTPEC3
148		/* There is a bug in Artpec-3 (voodoo TR 78) that requires
149		 * us to go to lower frequency for the reset to be reliable
150		 */
151		reg_clkgen_rw_clk_ctrl ctrl =
152			REG_RD(clkgen, regi_clkgen, rw_clk_ctrl);
153		ctrl.pll = 0;
154		REG_WR(clkgen, regi_clkgen, rw_clk_ctrl, ctrl);
155#endif
156		while(1);
157	}
158
159	/* Unexpected watchdog, stop the watchdog and dump registers. */
160	stop_watchdog();
161	printk(KERN_WARNING "Oops: bitten by watchdog\n");
162	show_registers(regs);
163	oops_in_progress = 0;
164	printk("\n"); /* Flush mtdoops.  */
165#ifndef CONFIG_ETRAX_WATCHDOG_NICE_DOGGY
166	reset_watchdog();
167#endif
168	while(1) /* nothing */;
169#endif
170}
171
172extern void cris_profile_sample(struct pt_regs *regs);
173static void __iomem *timer_base;
174
175static void crisv32_clkevt_mode(enum clock_event_mode mode,
176				struct clock_event_device *dev)
177{
178	reg_timer_rw_tmr0_ctrl ctrl = {
179		.op = regk_timer_hold,
180		.freq = regk_timer_f100,
181	};
182
183	REG_WR(timer, timer_base, rw_tmr0_ctrl, ctrl);
184}
185
186static int crisv32_clkevt_next_event(unsigned long evt,
187				     struct clock_event_device *dev)
188{
189	reg_timer_rw_tmr0_ctrl ctrl = {
190		.op = regk_timer_ld,
191		.freq = regk_timer_f100,
192	};
193
194	REG_WR(timer, timer_base, rw_tmr0_div, evt);
195	REG_WR(timer, timer_base, rw_tmr0_ctrl, ctrl);
196
197	ctrl.op = regk_timer_run;
198	REG_WR(timer, timer_base, rw_tmr0_ctrl, ctrl);
199
200	return 0;
201}
202
203static irqreturn_t crisv32_timer_interrupt(int irq, void *dev_id)
204{
205	struct clock_event_device *evt = dev_id;
206	reg_timer_rw_tmr0_ctrl ctrl = {
207		.op = regk_timer_hold,
208		.freq = regk_timer_f100,
209	};
210	reg_timer_rw_ack_intr ack = { .tmr0 = 1 };
211	reg_timer_r_masked_intr intr;
212
213	intr = REG_RD(timer, timer_base, r_masked_intr);
214	if (!intr.tmr0)
215		return IRQ_NONE;
216
217	REG_WR(timer, timer_base, rw_tmr0_ctrl, ctrl);
218	REG_WR(timer, timer_base, rw_ack_intr, ack);
219
220	reset_watchdog();
221#ifdef CONFIG_SYSTEM_PROFILER
222	cris_profile_sample(get_irq_regs());
223#endif
224
225	evt->event_handler(evt);
226
227	return IRQ_HANDLED;
228}
229
230static struct clock_event_device crisv32_clockevent = {
231	.name = "crisv32-timer",
232	.rating = 300,
233	.features = CLOCK_EVT_FEAT_ONESHOT,
234	.set_mode = crisv32_clkevt_mode,
235	.set_next_event = crisv32_clkevt_next_event,
236};
237
238/* Timer is IRQF_SHARED so drivers can add stuff to the timer irq chain. */
239static struct irqaction irq_timer = {
240	.handler = crisv32_timer_interrupt,
241	.flags = IRQF_TIMER | IRQF_SHARED,
242	.name = "crisv32-timer",
243	.dev_id = &crisv32_clockevent,
244};
245
246static u64 notrace crisv32_timer_sched_clock(void)
247{
248	return REG_RD(timer, timer_base, r_time);
249}
250
251static void __init crisv32_timer_init(void)
252{
253	reg_timer_rw_intr_mask timer_intr_mask;
254	reg_timer_rw_tmr0_ctrl ctrl = {
255		.op = regk_timer_hold,
256		.freq = regk_timer_f100,
257	};
258
259	REG_WR(timer, timer_base, rw_tmr0_ctrl, ctrl);
260
261	timer_intr_mask = REG_RD(timer, timer_base, rw_intr_mask);
262	timer_intr_mask.tmr0 = 1;
263	REG_WR(timer, timer_base, rw_intr_mask, timer_intr_mask);
264}
265
266void __init time_init(void)
267{
268	int irq;
269	int ret;
270
271	/* Probe for the RTC and read it if it exists.
272	 * Before the RTC can be probed the loops_per_usec variable needs
273	 * to be initialized to make usleep work. A better value for
274	 * loops_per_usec is calculated by the kernel later once the
275	 * clock has started.
276	 */
277	loops_per_usec = 50;
278
279	irq = TIMER0_INTR_VECT;
280	timer_base = (void __iomem *) regi_timer0;
281
282	crisv32_timer_init();
283
284	sched_clock_register(crisv32_timer_sched_clock, 32,
285			     CRISV32_TIMER_FREQ);
286
287	clocksource_mmio_init(timer_base + REG_RD_ADDR_timer_r_time,
288			      "crisv32-timer", CRISV32_TIMER_FREQ,
289			      300, 32, clocksource_mmio_readl_up);
290
291	crisv32_clockevent.cpumask = cpu_possible_mask;
292	crisv32_clockevent.irq = irq;
293
294	ret = setup_irq(irq, &irq_timer);
295	if (ret)
296		pr_warn("failed to setup irq %d\n", irq);
297
298	clockevents_config_and_register(&crisv32_clockevent,
299					CRISV32_TIMER_FREQ,
300					2, 0xffffffff);
301
302	/* Enable watchdog if we should use one. */
303
304#if defined(CONFIG_ETRAX_WATCHDOG)
305	printk(KERN_INFO "Enabling watchdog...\n");
306	start_watchdog();
307
308	/* If we use the hardware watchdog, we want to trap it as an NMI
309	 * and dump registers before it resets us.  For this to happen, we
310	 * must set the "m" NMI enable flag (which once set, is unset only
311	 * when an NMI is taken). */
312	{
313		unsigned long flags;
314		local_save_flags(flags);
315		flags |= (1<<30); /* NMI M flag is at bit 30 */
316		local_irq_restore(flags);
317	}
318#endif
319
320#ifdef CONFIG_CPU_FREQ
321	cpufreq_register_notifier(&cris_time_freq_notifier_block,
322				  CPUFREQ_TRANSITION_NOTIFIER);
323#endif
324}
325
326#ifdef CONFIG_CPU_FREQ
327static int cris_time_freq_notifier(struct notifier_block *nb,
328				   unsigned long val, void *data)
329{
330	struct cpufreq_freqs *freqs = data;
331	if (val == CPUFREQ_POSTCHANGE) {
332		reg_timer_r_tmr0_data data;
333		reg_timer_rw_tmr0_div div = (freqs->new * 500) / HZ;
334		do {
335			data = REG_RD(timer, timer_regs[freqs->cpu],
336				r_tmr0_data);
337		} while (data > 20);
338		REG_WR(timer, timer_regs[freqs->cpu], rw_tmr0_div, div);
339	}
340	return 0;
341}
342#endif
343