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
26static struct irqaction bfin_timer_irq = {
27	.name = "Blackfin Timer Tick",
28};
29
30#if defined(CONFIG_IPIPE)
31void __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
48void __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
70static void __init
71time_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 */
88static 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
121irqreturn_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
135void 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
142void __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