Home Home > GIT Browse
summaryrefslogtreecommitdiff
blob: 5c40be9880f5f3c1a12197ae964e228f24547a4f (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
/*
 * Copyright (C) 2012 Broadcom Corporation
 *
 * 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 version 2.
 *
 * This program is distributed "as is" WITHOUT ANY WARRANTY of any
 * kind, whether express or implied; without even the implied warranty
 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

#include <linux/init.h>
#include <linux/irq.h>
#include <linux/interrupt.h>
#include <linux/jiffies.h>
#include <linux/clockchips.h>
#include <linux/types.h>
#include <linux/clk.h>

#include <linux/io.h>

#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>


#define KONA_GPTIMER_STCS_OFFSET			0x00000000
#define KONA_GPTIMER_STCLO_OFFSET			0x00000004
#define KONA_GPTIMER_STCHI_OFFSET			0x00000008
#define KONA_GPTIMER_STCM0_OFFSET			0x0000000C

#define KONA_GPTIMER_STCS_TIMER_MATCH_SHIFT		0
#define KONA_GPTIMER_STCS_COMPARE_ENABLE_SHIFT		4

struct kona_bcm_timers {
	int tmr_irq;
	void __iomem *tmr_regs;
};

static struct kona_bcm_timers timers;

static u32 arch_timer_rate;

/*
 * We use the peripheral timers for system tick, the cpu global timer for
 * profile tick
 */
static void kona_timer_disable_and_clear(void __iomem *base)
{
	uint32_t reg;

	/*
	 * clear and disable interrupts
	 * We are using compare/match register 0 for our system interrupts
	 */
	reg = readl(base + KONA_GPTIMER_STCS_OFFSET);

	/* Clear compare (0) interrupt */
	reg |= 1 << KONA_GPTIMER_STCS_TIMER_MATCH_SHIFT;
	/* disable compare */
	reg &= ~(1 << KONA_GPTIMER_STCS_COMPARE_ENABLE_SHIFT);

	writel(reg, base + KONA_GPTIMER_STCS_OFFSET);

}

static int
kona_timer_get_counter(void __iomem *timer_base, uint32_t *msw, uint32_t *lsw)
{
	int loop_limit = 3;

	/*
	 * Read 64-bit free running counter
	 * 1. Read hi-word
	 * 2. Read low-word
	 * 3. Read hi-word again
	 * 4.1
	 *      if new hi-word is not equal to previously read hi-word, then
	 *      start from #1
	 * 4.2
	 *      if new hi-word is equal to previously read hi-word then stop.
	 */

	do {
		*msw = readl(timer_base + KONA_GPTIMER_STCHI_OFFSET);
		*lsw = readl(timer_base + KONA_GPTIMER_STCLO_OFFSET);
		if (*msw == readl(timer_base + KONA_GPTIMER_STCHI_OFFSET))
			break;
	} while (--loop_limit);
	if (!loop_limit) {
		pr_err("bcm_kona_timer: getting counter failed.\n");
		pr_err(" Timer will be impacted\n");
		return -ETIMEDOUT;
	}

	return 0;
}

static int kona_timer_set_next_event(unsigned long clc,
				  struct clock_event_device *unused)
{
	/*
	 * timer (0) is disabled by the timer interrupt already
	 * so, here we reload the next event value and re-enable
	 * the timer.
	 *
	 * This way, we are potentially losing the time between
	 * timer-interrupt->set_next_event. CPU local timers, when
	 * they come in should get rid of skew.
	 */

	uint32_t lsw, msw;
	uint32_t reg;
	int ret;

	ret = kona_timer_get_counter(timers.tmr_regs, &msw, &lsw);
	if (ret)
		return ret;

	/* Load the "next" event tick value */
	writel(lsw + clc, timers.tmr_regs + KONA_GPTIMER_STCM0_OFFSET);

	/* Enable compare */
	reg = readl(timers.tmr_regs + KONA_GPTIMER_STCS_OFFSET);
	reg |= (1 << KONA_GPTIMER_STCS_COMPARE_ENABLE_SHIFT);
	writel(reg, timers.tmr_regs + KONA_GPTIMER_STCS_OFFSET);

	return 0;
}

static int kona_timer_shutdown(struct clock_event_device *evt)
{
	kona_timer_disable_and_clear(timers.tmr_regs);
	return 0;
}

static struct clock_event_device kona_clockevent_timer = {
	.name = "timer 1",
	.features = CLOCK_EVT_FEAT_ONESHOT,
	.set_next_event = kona_timer_set_next_event,
	.set_state_shutdown = kona_timer_shutdown,
	.tick_resume = kona_timer_shutdown,
};

static void __init kona_timer_clockevents_init(void)
{
	kona_clockevent_timer.cpumask = cpumask_of(0);
	clockevents_config_and_register(&kona_clockevent_timer,
		arch_timer_rate, 6, 0xffffffff);
}

static irqreturn_t kona_timer_interrupt(int irq, void *dev_id)
{
	struct clock_event_device *evt = &kona_clockevent_timer;

	kona_timer_disable_and_clear(timers.tmr_regs);
	evt->event_handler(evt);
	return IRQ_HANDLED;
}

static struct irqaction kona_timer_irq = {
	.name = "Kona Timer Tick",
	.flags = IRQF_TIMER,
	.handler = kona_timer_interrupt,
};

static int __init kona_timer_init(struct device_node *node)
{
	u32 freq;
	struct clk *external_clk;

	external_clk = of_clk_get_by_name(node, NULL);

	if (!IS_ERR(external_clk)) {
		arch_timer_rate = clk_get_rate(external_clk);
		clk_prepare_enable(external_clk);
	} else if (!of_property_read_u32(node, "clock-frequency", &freq)) {
		arch_timer_rate = freq;
	} else {
		pr_err("Kona Timer v1 unable to determine clock-frequency\n");
		return -EINVAL;
	}

	/* Setup IRQ numbers */
	timers.tmr_irq = irq_of_parse_and_map(node, 0);

	/* Setup IO addresses */
	timers.tmr_regs = of_iomap(node, 0);

	kona_timer_disable_and_clear(timers.tmr_regs);

	kona_timer_clockevents_init();
	setup_irq(timers.tmr_irq, &kona_timer_irq);
	kona_timer_set_next_event((arch_timer_rate / HZ), NULL);

	return 0;
}

TIMER_OF_DECLARE(brcm_kona, "brcm,kona-timer", kona_timer_init);
/*
 * bcm,kona-timer is deprecated by brcm,kona-timer
 * being kept here for driver compatibility
 */
TIMER_OF_DECLARE(bcm_kona, "bcm,kona-timer", kona_timer_init);