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