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1 /*
2  * arch/blackfin/kernel/time.c
3  *
4  * This file contains the Blackfin-specific time handling details.
5  * Most of the stuff is located in the machine specific files.
6  *
7  * Copyright 2004-2008 Analog Devices Inc.
8  * Licensed under the GPL-2 or later.
9  */
10 
11 #include <linux/module.h>
12 #include <linux/profile.h>
13 #include <linux/interrupt.h>
14 #include <linux/time.h>
15 #include <linux/irq.h>
16 #include <linux/delay.h>
17 #include <linux/sched.h>
18 
19 #include <asm/blackfin.h>
20 #include <asm/time.h>
21 #include <asm/gptimers.h>
22 
23 /* This is an NTP setting */
24 #define	TICK_SIZE (tick_nsec / 1000)
25 
26 static struct irqaction bfin_timer_irq = {
27 	.name = "Blackfin Timer Tick",
28 };
29 
30 #if defined(CONFIG_IPIPE)
setup_system_timer0(void)31 void __init setup_system_timer0(void)
32 {
33 	/* Power down the core timer, just to play safe. */
34 	bfin_write_TCNTL(0);
35 
36 	disable_gptimers(TIMER0bit);
37 	set_gptimer_status(0, TIMER_STATUS_TRUN0);
38 	while (get_gptimer_status(0) & TIMER_STATUS_TRUN0)
39 		udelay(10);
40 
41 	set_gptimer_config(0, 0x59); /* IRQ enable, periodic, PWM_OUT, SCLKed, OUT PAD disabled */
42 	set_gptimer_period(TIMER0_id, get_sclk() / HZ);
43 	set_gptimer_pwidth(TIMER0_id, 1);
44 	SSYNC();
45 	enable_gptimers(TIMER0bit);
46 }
47 #else
setup_core_timer(void)48 void __init setup_core_timer(void)
49 {
50 	u32 tcount;
51 
52 	/* power up the timer, but don't enable it just yet */
53 	bfin_write_TCNTL(TMPWR);
54 	CSYNC();
55 
56 	/* the TSCALE prescaler counter */
57 	bfin_write_TSCALE(TIME_SCALE - 1);
58 
59 	tcount = ((get_cclk() / (HZ * TIME_SCALE)) - 1);
60 	bfin_write_TPERIOD(tcount);
61 	bfin_write_TCOUNT(tcount);
62 
63 	/* now enable the timer */
64 	CSYNC();
65 
66 	bfin_write_TCNTL(TAUTORLD | TMREN | TMPWR);
67 }
68 #endif
69 
70 static void __init
time_sched_init(irqreturn_t (* timer_routine)(int,void *))71 time_sched_init(irqreturn_t(*timer_routine) (int, void *))
72 {
73 #if defined(CONFIG_IPIPE)
74 	setup_system_timer0();
75 	bfin_timer_irq.handler = timer_routine;
76 	setup_irq(IRQ_TIMER0, &bfin_timer_irq);
77 #else
78 	setup_core_timer();
79 	bfin_timer_irq.handler = timer_routine;
80 	setup_irq(IRQ_CORETMR, &bfin_timer_irq);
81 #endif
82 }
83 
84 #ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
85 /*
86  * Should return useconds since last timer tick
87  */
blackfin_gettimeoffset(void)88 static u32 blackfin_gettimeoffset(void)
89 {
90 	unsigned long offset;
91 	unsigned long clocks_per_jiffy;
92 
93 #if defined(CONFIG_IPIPE)
94 	clocks_per_jiffy = bfin_read_TIMER0_PERIOD();
95 	offset = bfin_read_TIMER0_COUNTER() / \
96 		(((clocks_per_jiffy + 1) * HZ) / USEC_PER_SEC);
97 
98 	if ((get_gptimer_status(0) & TIMER_STATUS_TIMIL0) && offset < (100000 / HZ / 2))
99 		offset += (USEC_PER_SEC / HZ);
100 #else
101 	clocks_per_jiffy = bfin_read_TPERIOD();
102 	offset = (clocks_per_jiffy - bfin_read_TCOUNT()) / \
103 		(((clocks_per_jiffy + 1) * HZ) / USEC_PER_SEC);
104 
105 	/* Check if we just wrapped the counters and maybe missed a tick */
106 	if ((bfin_read_ILAT() & (1 << IRQ_CORETMR))
107 		&& (offset < (100000 / HZ / 2)))
108 		offset += (USEC_PER_SEC / HZ);
109 #endif
110 	return offset;
111 }
112 #endif
113 
114 /*
115  * timer_interrupt() needs to keep up the real-time clock,
116  * as well as call the "xtime_update()" routine every clocktick
117  */
118 #ifdef CONFIG_CORE_TIMER_IRQ_L1
119 __attribute__((l1_text))
120 #endif
timer_interrupt(int irq,void * dummy)121 irqreturn_t timer_interrupt(int irq, void *dummy)
122 {
123 	xtime_update(1);
124 
125 #ifdef CONFIG_IPIPE
126 	update_root_process_times(get_irq_regs());
127 #else
128 	update_process_times(user_mode(get_irq_regs()));
129 #endif
130 	profile_tick(CPU_PROFILING);
131 
132 	return IRQ_HANDLED;
133 }
134 
read_persistent_clock(struct timespec * ts)135 void read_persistent_clock(struct timespec *ts)
136 {
137 	time_t secs_since_1970 = (365 * 37 + 9) * 24 * 60 * 60;	/* 1 Jan 2007 */
138 	ts->tv_sec = secs_since_1970;
139 	ts->tv_nsec = 0;
140 }
141 
time_init(void)142 void __init time_init(void)
143 {
144 #ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
145 	arch_gettimeoffset = blackfin_gettimeoffset;
146 #endif
147 
148 #ifdef CONFIG_RTC_DRV_BFIN
149 	/* [#2663] hack to filter junk RTC values that would cause
150 	 * userspace to have to deal with time values greater than
151 	 * 2^31 seconds (which uClibc cannot cope with yet)
152 	 */
153 	if ((bfin_read_RTC_STAT() & 0xC0000000) == 0xC0000000) {
154 		printk(KERN_NOTICE "bfin-rtc: invalid date; resetting\n");
155 		bfin_write_RTC_STAT(0);
156 	}
157 #endif
158 
159 	time_sched_init(timer_interrupt);
160 }
161