1 /*
2 * linux/arch/arm/mach-omap1/timer32k.c
3 *
4 * OMAP 32K Timer
5 *
6 * Copyright (C) 2004 - 2005 Nokia Corporation
7 * Partial timer rewrite and additional dynamic tick timer support by
8 * Tony Lindgen <tony@atomide.com> and
9 * Tuukka Tikkanen <tuukka.tikkanen@elektrobit.com>
10 * OMAP Dual-mode timer framework support by Timo Teras
11 *
12 * MPU timer code based on the older MPU timer code for OMAP
13 * Copyright (C) 2000 RidgeRun, Inc.
14 * Author: Greg Lonnon <glonnon@ridgerun.com>
15 *
16 * This program is free software; you can redistribute it and/or modify it
17 * under the terms of the GNU General Public License as published by the
18 * Free Software Foundation; either version 2 of the License, or (at your
19 * option) any later version.
20 *
21 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
22 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
23 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN
24 * NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
25 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
26 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
27 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
28 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
29 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
30 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
31 *
32 * You should have received a copy of the GNU General Public License along
33 * with this program; if not, write to the Free Software Foundation, Inc.,
34 * 675 Mass Ave, Cambridge, MA 02139, USA.
35 */
36
37 #include <linux/kernel.h>
38 #include <linux/init.h>
39 #include <linux/delay.h>
40 #include <linux/interrupt.h>
41 #include <linux/sched.h>
42 #include <linux/spinlock.h>
43 #include <linux/err.h>
44 #include <linux/clk.h>
45 #include <linux/clocksource.h>
46 #include <linux/clockchips.h>
47 #include <linux/io.h>
48
49 #include <asm/leds.h>
50 #include <asm/irq.h>
51 #include <asm/mach/irq.h>
52 #include <asm/mach/time.h>
53
54 #include <plat/dmtimer.h>
55
56 #include <mach/hardware.h>
57
58 #include "common.h"
59
60 /*
61 * ---------------------------------------------------------------------------
62 * 32KHz OS timer
63 *
64 * This currently works only on 16xx, as 1510 does not have the continuous
65 * 32KHz synchronous timer. The 32KHz synchronous timer is used to keep track
66 * of time in addition to the 32KHz OS timer. Using only the 32KHz OS timer
67 * on 1510 would be possible, but the timer would not be as accurate as
68 * with the 32KHz synchronized timer.
69 * ---------------------------------------------------------------------------
70 */
71
72 /* 16xx specific defines */
73 #define OMAP1_32K_TIMER_BASE 0xfffb9000
74 #define OMAP1_32K_TIMER_CR 0x08
75 #define OMAP1_32K_TIMER_TVR 0x00
76 #define OMAP1_32K_TIMER_TCR 0x04
77
78 #define OMAP_32K_TICKS_PER_SEC (32768)
79
80 /*
81 * TRM says 1 / HZ = ( TVR + 1) / 32768, so TRV = (32768 / HZ) - 1
82 * so with HZ = 128, TVR = 255.
83 */
84 #define OMAP_32K_TIMER_TICK_PERIOD ((OMAP_32K_TICKS_PER_SEC / HZ) - 1)
85
86 #define JIFFIES_TO_HW_TICKS(nr_jiffies, clock_rate) \
87 (((nr_jiffies) * (clock_rate)) / HZ)
88
omap_32k_timer_write(int val,int reg)89 static inline void omap_32k_timer_write(int val, int reg)
90 {
91 omap_writew(val, OMAP1_32K_TIMER_BASE + reg);
92 }
93
omap_32k_timer_read(int reg)94 static inline unsigned long omap_32k_timer_read(int reg)
95 {
96 return omap_readl(OMAP1_32K_TIMER_BASE + reg) & 0xffffff;
97 }
98
omap_32k_timer_start(unsigned long load_val)99 static inline void omap_32k_timer_start(unsigned long load_val)
100 {
101 if (!load_val)
102 load_val = 1;
103 omap_32k_timer_write(load_val, OMAP1_32K_TIMER_TVR);
104 omap_32k_timer_write(0x0f, OMAP1_32K_TIMER_CR);
105 }
106
omap_32k_timer_stop(void)107 static inline void omap_32k_timer_stop(void)
108 {
109 omap_32k_timer_write(0x0, OMAP1_32K_TIMER_CR);
110 }
111
112 #define omap_32k_timer_ack_irq()
113
omap_32k_timer_set_next_event(unsigned long delta,struct clock_event_device * dev)114 static int omap_32k_timer_set_next_event(unsigned long delta,
115 struct clock_event_device *dev)
116 {
117 omap_32k_timer_start(delta);
118
119 return 0;
120 }
121
omap_32k_timer_set_mode(enum clock_event_mode mode,struct clock_event_device * evt)122 static void omap_32k_timer_set_mode(enum clock_event_mode mode,
123 struct clock_event_device *evt)
124 {
125 omap_32k_timer_stop();
126
127 switch (mode) {
128 case CLOCK_EVT_MODE_PERIODIC:
129 omap_32k_timer_start(OMAP_32K_TIMER_TICK_PERIOD);
130 break;
131 case CLOCK_EVT_MODE_ONESHOT:
132 case CLOCK_EVT_MODE_UNUSED:
133 case CLOCK_EVT_MODE_SHUTDOWN:
134 break;
135 case CLOCK_EVT_MODE_RESUME:
136 break;
137 }
138 }
139
140 static struct clock_event_device clockevent_32k_timer = {
141 .name = "32k-timer",
142 .features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
143 .shift = 32,
144 .set_next_event = omap_32k_timer_set_next_event,
145 .set_mode = omap_32k_timer_set_mode,
146 };
147
omap_32k_timer_interrupt(int irq,void * dev_id)148 static irqreturn_t omap_32k_timer_interrupt(int irq, void *dev_id)
149 {
150 struct clock_event_device *evt = &clockevent_32k_timer;
151 omap_32k_timer_ack_irq();
152
153 evt->event_handler(evt);
154
155 return IRQ_HANDLED;
156 }
157
158 static struct irqaction omap_32k_timer_irq = {
159 .name = "32KHz timer",
160 .flags = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
161 .handler = omap_32k_timer_interrupt,
162 };
163
omap_init_32k_timer(void)164 static __init void omap_init_32k_timer(void)
165 {
166 setup_irq(INT_OS_TIMER, &omap_32k_timer_irq);
167
168 clockevent_32k_timer.mult = div_sc(OMAP_32K_TICKS_PER_SEC,
169 NSEC_PER_SEC,
170 clockevent_32k_timer.shift);
171 clockevent_32k_timer.max_delta_ns =
172 clockevent_delta2ns(0xfffffffe, &clockevent_32k_timer);
173 clockevent_32k_timer.min_delta_ns =
174 clockevent_delta2ns(1, &clockevent_32k_timer);
175
176 clockevent_32k_timer.cpumask = cpumask_of(0);
177 clockevents_register_device(&clockevent_32k_timer);
178 }
179
180 /*
181 * ---------------------------------------------------------------------------
182 * Timer initialization
183 * ---------------------------------------------------------------------------
184 */
omap_32k_timer_init(void)185 bool __init omap_32k_timer_init(void)
186 {
187 omap_init_clocksource_32k();
188 omap_init_32k_timer();
189
190 return true;
191 }
192