summaryrefslogtreecommitdiff
path: root/arch/arm/plat-mxc/pit.c
blob: ba71bda51c06d2fc0b5178388a53b2bfc4844261 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
/*
 *  linux/arch/arm/plat-mxc/pit.c
 *
 *  Copyright 2012 Freescale Semiconductor, Inc.
 *  based on linux/arch/arm/plat-mxc/epit.c
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
 * MA 02110-1301, USA.
 */
#include <asm/sched_clock.h>


#define PITMCR		0x00
#define PITLTMR64H	0xE0
#define PITLTMR64L      0xE4

#define PITOFFSET	0x120
#define PITLDVAL	0x00
#define PITCVAL		0x04
#define PITTCTRL	0x08
#define PITTFLG		0x0C

/*
 * Total 8 pit timer, each memory map occupy 0x10 Bytes
 * get base offset for pit(n)
 */
#define PITOFFSETx(n)	(PITOFFSET + 0x10*n)

/* bit definitation */
#define PITMCR_MDIS		(1 << 1)
#define PITMCR_FRZ		(1 << 0)

#define PITTCTRL_TEN		(1 << 0)
#define PITTCTRL_TIE		(1 << 1)
#define	PITCTRL_CHN		(1 << 2)

#define PITTFLG_TIF		(1 << 0)

#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/clockchips.h>
#include <linux/clk.h>
#include <linux/delay.h>
#include <mach/hardware.h>
#include <asm/mach/time.h>
#include <mach/common.h>

static cycle_t pit_cnt;
static struct clock_event_device clockevent_pit;
static enum clock_event_mode clockevent_mode = CLOCK_EVT_MODE_UNUSED;

static void __iomem *timer_base;
static unsigned long pit_cycle_per_jiffy;

static inline void pit_irq_disable(void)
{
	u32 val;

	val = __raw_readl(timer_base + PITOFFSET + PITTCTRL);
	val &= ~PITTCTRL_TIE;
	__raw_writel(val, timer_base + PITOFFSET + PITTCTRL);
}

static inline void pit_irq_enable(void)
{
	u32 val;

	val = __raw_readl(timer_base + PITOFFSET + PITTCTRL);
	val |= PITTCTRL_TIE;
	__raw_writel(val, timer_base + PITOFFSET + PITTCTRL);
}

static void pit_irq_acknowledge(void)
{
	__raw_writel(PITTFLG_TIF, timer_base + PITOFFSET + PITTFLG);
}

static cycle_t pit_read_clk(struct clocksource *cs);

static DEFINE_CLOCK_DATA(cd);
static void __iomem *sched_clock_reg;

static void notrace mvf_update_sched_clock(void)
{
	cycle_t cyc = sched_clock_reg ? __raw_readl(sched_clock_reg) : 0;
	update_sched_clock(&cd, cyc, (u32)~0);
}
static int __init pit_clocksource_init(struct clk *timer_clk)
{
	unsigned int c = clk_get_rate(timer_clk);
	void __iomem *reg = timer_base + PITOFFSET + PITCVAL;

	sched_clock_reg = reg;

	init_sched_clock(&cd, mvf_update_sched_clock, 32, c);
	return clocksource_mmio_init(timer_base + PITOFFSET + PITCVAL, "pit",
			c, 200, 32,
			pit_read_clk/*clocksource_mmio_readl_down*/);
}

/* clock event */

static int pit_set_next_event(unsigned long evt,
			      struct clock_event_device *unused)
{
	return 0;
}

static void pit_set_mode(enum clock_event_mode mode,
				struct clock_event_device *evt)
{
	unsigned long flags;

	/*
	 * The timer interrupt generation is disabled at least
	 * for enough time to call epit_set_next_event()
	 */
	local_irq_save(flags);

	/* Disable interrupt in PIT module */
	pit_irq_disable();

	if (mode != clockevent_mode) {
		/* Set event time into far-far future */

		/* Clear pending interrupt */
		pit_irq_acknowledge();
	}

	/* Remember timer mode */
	clockevent_mode = mode;
	local_irq_restore(flags);

	switch (mode) {
	case CLOCK_EVT_MODE_PERIODIC:

		__raw_writel(0, timer_base + PITOFFSET + PITTCTRL);
		__raw_writel(pit_cycle_per_jiffy,
				timer_base + PITOFFSET + PITLDVAL);
		__raw_writel(PITTCTRL_TEN, timer_base + PITOFFSET + PITTCTRL);

		pit_irq_enable();

		break;
	case CLOCK_EVT_MODE_ONESHOT:
	/*
	 * Do not put overhead of interrupt enable/disable into
	 * epit_set_next_event(), the core has about 4 minutes
	 * to call epit_set_next_event() or shutdown clock after
	 * mode switching
	 */
		local_irq_save(flags);
		pit_irq_enable();
		local_irq_restore(flags);
		break;
	case CLOCK_EVT_MODE_SHUTDOWN:
	case CLOCK_EVT_MODE_UNUSED:
	case CLOCK_EVT_MODE_RESUME:
		/* Left event sources disabled, no more interrupts appear */
		break;
	}
}

/*
 * IRQ handler for the timer
 */
static irqreturn_t pit_timer_interrupt(int irq, void *dev_id)
{
	struct clock_event_device *evt = &clockevent_pit;

	pit_irq_acknowledge();

	pit_cnt += pit_cycle_per_jiffy;

	evt->event_handler(evt);

	return IRQ_HANDLED;
}

static cycle_t pit_read_clk(struct clocksource *cs)
{
	unsigned long flags;
	cycle_t cycles;
	u32 pcntr;

	local_irq_save(flags);
	pcntr = __raw_readl(timer_base + PITOFFSET + PITCVAL);
	cycles = pit_cnt;
	local_irq_restore(flags);

	return cycles + pit_cycle_per_jiffy - pcntr;
}


static struct irqaction pit_timer_irq = {
	.name		= "MVF PIT Timer Tick",
	.flags		= IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
	.handler	= pit_timer_interrupt,
};

static struct clock_event_device clockevent_pit = {
	.name		= "pit",
	.features	= CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
	.shift		= 32,
	.set_mode	= pit_set_mode,
	.set_next_event	= pit_set_next_event,
	.rating		= 100,
};

static int __init pit_clockevent_init(struct clk *timer_clk)
{
	unsigned int c = clk_get_rate(timer_clk);

	clockevent_pit.mult = div_sc(c, NSEC_PER_SEC,
					clockevent_pit.shift);
	clockevent_pit.max_delta_ns =
			clockevent_delta2ns(0xfffffffe, &clockevent_pit);
	clockevent_pit.min_delta_ns =
			clockevent_delta2ns(0x800, &clockevent_pit);
	clockevent_pit.cpumask = cpumask_of(0);
	clockevents_register_device(&clockevent_pit);

	return 0;
}

void __init pit_timer_init(struct clk *timer_clk, void __iomem *base, int irq)
{

	timer_base = base;

	pit_cycle_per_jiffy = clk_get_rate(timer_clk)/(HZ);

	/*
	 * Initialise to a known state (all timers off, and timing reset)
	 */
	__raw_writel(0x0, timer_base + PITMCR);

	__raw_writel(0, timer_base + PITOFFSET + PITTCTRL);
	__raw_writel(0xffffffff, timer_base + PITOFFSET + PITLDVAL);
	__raw_writel(PITTCTRL_TEN, timer_base + PITOFFSET + PITTCTRL);

	/* init and register the timer to the framework */
	pit_clocksource_init(timer_clk);

	pit_clockevent_init(timer_clk);

	/* Make irqs happen */
	setup_irq(irq, &pit_timer_irq);
}