1/*
2 * linux/arch/arm/plat-omap/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
48#include <asm/system.h>
49#include <asm/hardware.h>
50#include <asm/io.h>
51#include <asm/leds.h>
52#include <asm/irq.h>
53#include <asm/mach/irq.h>
54#include <asm/mach/time.h>
55#include <asm/arch/dmtimer.h>
56
57struct sys_timer omap_timer;
58
59/*
60 * ---------------------------------------------------------------------------
61 * 32KHz OS timer
62 *
63 * This currently works only on 16xx, as 1510 does not have the continuous
64 * 32KHz synchronous timer. The 32KHz synchronous timer is used to keep track
65 * of time in addition to the 32KHz OS timer. Using only the 32KHz OS timer
66 * on 1510 would be possible, but the timer would not be as accurate as
67 * with the 32KHz synchronized timer.
68 * ---------------------------------------------------------------------------
69 */
70
71#if defined(CONFIG_ARCH_OMAP16XX)
72#define TIMER_32K_SYNCHRONIZED		0xfffbc410
73#elif defined(CONFIG_ARCH_OMAP24XX)
74#define TIMER_32K_SYNCHRONIZED		0x48004010
75#else
76#error OMAP 32KHz timer does not currently work on 15XX!
77#endif
78
79/* 16xx specific defines */
80#define OMAP1_32K_TIMER_BASE		0xfffb9000
81#define OMAP1_32K_TIMER_CR		0x08
82#define OMAP1_32K_TIMER_TVR		0x00
83#define OMAP1_32K_TIMER_TCR		0x04
84
85#define OMAP_32K_TICKS_PER_SEC		(32768)
86
87/*
88 * TRM says 1 / HZ = ( TVR + 1) / 32768, so TRV = (32768 / HZ) - 1
89 * so with HZ = 128, TVR = 255.
90 */
91#define OMAP_32K_TIMER_TICK_PERIOD	((OMAP_32K_TICKS_PER_SEC / HZ) - 1)
92
93#define JIFFIES_TO_HW_TICKS(nr_jiffies, clock_rate)			\
94				(((nr_jiffies) * (clock_rate)) / HZ)
95
96#if defined(CONFIG_ARCH_OMAP1)
97
98static inline void omap_32k_timer_write(int val, int reg)
99{
100	omap_writew(val, OMAP1_32K_TIMER_BASE + reg);
101}
102
103static inline unsigned long omap_32k_timer_read(int reg)
104{
105	return omap_readl(OMAP1_32K_TIMER_BASE + reg) & 0xffffff;
106}
107
108static inline void omap_32k_timer_start(unsigned long load_val)
109{
110	if (!load_val)
111		load_val = 1;
112	omap_32k_timer_write(load_val, OMAP1_32K_TIMER_TVR);
113	omap_32k_timer_write(0x0f, OMAP1_32K_TIMER_CR);
114}
115
116static inline void omap_32k_timer_stop(void)
117{
118	omap_32k_timer_write(0x0, OMAP1_32K_TIMER_CR);
119}
120
121#define omap_32k_timer_ack_irq()
122
123#elif defined(CONFIG_ARCH_OMAP2)
124
125static struct omap_dm_timer *gptimer;
126
127static inline void omap_32k_timer_start(unsigned long load_val)
128{
129	omap_dm_timer_set_load(gptimer, 1, 0xffffffff - load_val);
130	omap_dm_timer_set_int_enable(gptimer, OMAP_TIMER_INT_OVERFLOW);
131	omap_dm_timer_start(gptimer);
132}
133
134static inline void omap_32k_timer_stop(void)
135{
136	omap_dm_timer_stop(gptimer);
137}
138
139static inline void omap_32k_timer_ack_irq(void)
140{
141	u32 status = omap_dm_timer_read_status(gptimer);
142	omap_dm_timer_write_status(gptimer, status);
143}
144
145#endif
146
147static void omap_32k_timer_set_mode(enum clock_event_mode mode,
148				    struct clock_event_device *evt)
149{
150	switch (mode) {
151	case CLOCK_EVT_MODE_ONESHOT:
152	case CLOCK_EVT_MODE_PERIODIC:
153		omap_32k_timer_start(OMAP_32K_TIMER_TICK_PERIOD);
154		break;
155	case CLOCK_EVT_MODE_UNUSED:
156	case CLOCK_EVT_MODE_SHUTDOWN:
157		omap_32k_timer_stop();
158		break;
159	}
160}
161
162static struct clock_event_device clockevent_32k_timer = {
163	.name		= "32k-timer",
164	.features       = CLOCK_EVT_FEAT_PERIODIC,
165	.shift		= 32,
166	.set_mode	= omap_32k_timer_set_mode,
167};
168
169/*
170 * The 32KHz synchronized timer is an additional timer on 16xx.
171 * It is always running.
172 */
173static inline unsigned long omap_32k_sync_timer_read(void)
174{
175	return omap_readl(TIMER_32K_SYNCHRONIZED);
176}
177
178/*
179 * Rounds down to nearest usec. Note that this will overflow for larger values.
180 */
181static inline unsigned long omap_32k_ticks_to_usecs(unsigned long ticks_32k)
182{
183	return (ticks_32k * 5*5*5*5*5*5) >> 9;
184}
185
186/*
187 * Rounds down to nearest nsec.
188 */
189static inline unsigned long long
190omap_32k_ticks_to_nsecs(unsigned long ticks_32k)
191{
192	return (unsigned long long) ticks_32k * 1000 * 5*5*5*5*5*5 >> 9;
193}
194
195static unsigned long omap_32k_last_tick = 0;
196
197/*
198 * Returns current time from boot in nsecs. It's OK for this to wrap
199 * around for now, as it's just a relative time stamp.
200 */
201unsigned long long sched_clock(void)
202{
203	return omap_32k_ticks_to_nsecs(omap_32k_sync_timer_read());
204}
205
206static irqreturn_t omap_32k_timer_interrupt(int irq, void *dev_id)
207{
208	struct clock_event_device *evt = &clockevent_32k_timer;
209	omap_32k_timer_ack_irq();
210
211	evt->event_handler(evt);
212
213	return IRQ_HANDLED;
214}
215
216static struct irqaction omap_32k_timer_irq = {
217	.name		= "32KHz timer",
218	.flags		= IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
219	.handler	= omap_32k_timer_interrupt,
220};
221
222static __init void omap_init_32k_timer(void)
223{
224	if (cpu_class_is_omap1())
225		setup_irq(INT_OS_TIMER, &omap_32k_timer_irq);
226	omap_32k_last_tick = omap_32k_sync_timer_read();
227
228#ifdef CONFIG_ARCH_OMAP2
229	/* REVISIT: Check 24xx TIOCP_CFG settings after idle works */
230	if (cpu_is_omap24xx()) {
231		gptimer = omap_dm_timer_request_specific(1);
232		BUG_ON(gptimer == NULL);
233
234		omap_dm_timer_set_source(gptimer, OMAP_TIMER_SRC_32_KHZ);
235		setup_irq(omap_dm_timer_get_irq(gptimer), &omap_32k_timer_irq);
236		omap_dm_timer_set_int_enable(gptimer,
237			OMAP_TIMER_INT_CAPTURE | OMAP_TIMER_INT_OVERFLOW |
238			OMAP_TIMER_INT_MATCH);
239	}
240#endif
241
242	clockevent_32k_timer.mult = div_sc(OMAP_32K_TICKS_PER_SEC,
243					   NSEC_PER_SEC,
244					   clockevent_32k_timer.shift);
245	clockevent_32k_timer.max_delta_ns =
246		clockevent_delta2ns(0xfffffffe, &clockevent_32k_timer);
247	clockevent_32k_timer.min_delta_ns =
248		clockevent_delta2ns(1, &clockevent_32k_timer);
249
250	clockevent_32k_timer.cpumask = cpumask_of_cpu(0);
251	clockevents_register_device(&clockevent_32k_timer);
252}
253
254/*
255 * ---------------------------------------------------------------------------
256 * Timer initialization
257 * ---------------------------------------------------------------------------
258 */
259static void __init omap_timer_init(void)
260{
261#ifdef CONFIG_OMAP_DM_TIMER
262	omap_dm_timer_init();
263#endif
264	omap_init_32k_timer();
265}
266
267struct sys_timer omap_timer = {
268	.init		= omap_timer_init,
269};
270