2 * linux/arch/arm/mach-omap1/timer32k.c
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
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>
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.
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.
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.
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>
49 #include <asm/system.h>
50 #include <mach/hardware.h>
53 #include <asm/mach/irq.h>
54 #include <asm/mach/time.h>
56 #include <plat/dmtimer.h>
59 * ---------------------------------------------------------------------------
62 * This currently works only on 16xx, as 1510 does not have the continuous
63 * 32KHz synchronous timer. The 32KHz synchronous timer is used to keep track
64 * of time in addition to the 32KHz OS timer. Using only the 32KHz OS timer
65 * on 1510 would be possible, but the timer would not be as accurate as
66 * with the 32KHz synchronized timer.
67 * ---------------------------------------------------------------------------
70 /* 16xx specific defines */
71 #define OMAP1_32K_TIMER_BASE 0xfffb9000
72 #define OMAP1_32K_TIMER_CR 0x08
73 #define OMAP1_32K_TIMER_TVR 0x00
74 #define OMAP1_32K_TIMER_TCR 0x04
76 #define OMAP_32K_TICKS_PER_SEC (32768)
79 * TRM says 1 / HZ = ( TVR + 1) / 32768, so TRV = (32768 / HZ) - 1
80 * so with HZ = 128, TVR = 255.
82 #define OMAP_32K_TIMER_TICK_PERIOD ((OMAP_32K_TICKS_PER_SEC / HZ) - 1)
84 #define JIFFIES_TO_HW_TICKS(nr_jiffies, clock_rate) \
85 (((nr_jiffies) * (clock_rate)) / HZ)
87 static inline void omap_32k_timer_write(int val
, int reg
)
89 omap_writew(val
, OMAP1_32K_TIMER_BASE
+ reg
);
92 static inline unsigned long omap_32k_timer_read(int reg
)
94 return omap_readl(OMAP1_32K_TIMER_BASE
+ reg
) & 0xffffff;
97 static inline void omap_32k_timer_start(unsigned long load_val
)
101 omap_32k_timer_write(load_val
, OMAP1_32K_TIMER_TVR
);
102 omap_32k_timer_write(0x0f, OMAP1_32K_TIMER_CR
);
105 static inline void omap_32k_timer_stop(void)
107 omap_32k_timer_write(0x0, OMAP1_32K_TIMER_CR
);
110 #define omap_32k_timer_ack_irq()
112 static int omap_32k_timer_set_next_event(unsigned long delta
,
113 struct clock_event_device
*dev
)
115 omap_32k_timer_start(delta
);
120 static void omap_32k_timer_set_mode(enum clock_event_mode mode
,
121 struct clock_event_device
*evt
)
123 omap_32k_timer_stop();
126 case CLOCK_EVT_MODE_PERIODIC
:
127 omap_32k_timer_start(OMAP_32K_TIMER_TICK_PERIOD
);
129 case CLOCK_EVT_MODE_ONESHOT
:
130 case CLOCK_EVT_MODE_UNUSED
:
131 case CLOCK_EVT_MODE_SHUTDOWN
:
133 case CLOCK_EVT_MODE_RESUME
:
138 static struct clock_event_device clockevent_32k_timer
= {
140 .features
= CLOCK_EVT_FEAT_PERIODIC
| CLOCK_EVT_FEAT_ONESHOT
,
142 .set_next_event
= omap_32k_timer_set_next_event
,
143 .set_mode
= omap_32k_timer_set_mode
,
146 static irqreturn_t
omap_32k_timer_interrupt(int irq
, void *dev_id
)
148 struct clock_event_device
*evt
= &clockevent_32k_timer
;
149 omap_32k_timer_ack_irq();
151 evt
->event_handler(evt
);
156 static struct irqaction omap_32k_timer_irq
= {
157 .name
= "32KHz timer",
158 .flags
= IRQF_DISABLED
| IRQF_TIMER
| IRQF_IRQPOLL
,
159 .handler
= omap_32k_timer_interrupt
,
162 static __init
void omap_init_32k_timer(void)
164 setup_irq(INT_OS_TIMER
, &omap_32k_timer_irq
);
166 clockevent_32k_timer
.mult
= div_sc(OMAP_32K_TICKS_PER_SEC
,
168 clockevent_32k_timer
.shift
);
169 clockevent_32k_timer
.max_delta_ns
=
170 clockevent_delta2ns(0xfffffffe, &clockevent_32k_timer
);
171 clockevent_32k_timer
.min_delta_ns
=
172 clockevent_delta2ns(1, &clockevent_32k_timer
);
174 clockevent_32k_timer
.cpumask
= cpumask_of(0);
175 clockevents_register_device(&clockevent_32k_timer
);
179 * ---------------------------------------------------------------------------
180 * Timer initialization
181 * ---------------------------------------------------------------------------
183 bool __init
omap_32k_timer_init(void)
185 omap_init_clocksource_32k();
186 omap_init_32k_timer();