Home Home > GIT Browse
summaryrefslogtreecommitdiff
blob: f5b2eda30bf336f79fd0b9553b7b6f1ef44f8dd4 (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
/*
 * Keystone broadcast clock-event
 *
 * Copyright 2013 Texas Instruments, Inc.
 *
 * Author: Ivan Khoronzhuk <ivan.khoronzhuk@ti.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 */

#include <linux/clk.h>
#include <linux/clockchips.h>
#include <linux/clocksource.h>
#include <linux/interrupt.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>

#define TIMER_NAME			"timer-keystone"

/* Timer register offsets */
#define TIM12				0x10
#define TIM34				0x14
#define PRD12				0x18
#define PRD34				0x1c
#define TCR				0x20
#define TGCR				0x24
#define INTCTLSTAT			0x44

/* Timer register bitfields */
#define TCR_ENAMODE_MASK		0xC0
#define TCR_ENAMODE_ONESHOT_MASK	0x40
#define TCR_ENAMODE_PERIODIC_MASK	0x80

#define TGCR_TIM_UNRESET_MASK		0x03
#define INTCTLSTAT_ENINT_MASK		0x01

/**
 * struct keystone_timer: holds timer's data
 * @base: timer memory base address
 * @hz_period: cycles per HZ period
 * @event_dev: event device based on timer
 */
static struct keystone_timer {
	void __iomem *base;
	unsigned long hz_period;
	struct clock_event_device event_dev;
} timer;

static inline u32 keystone_timer_readl(unsigned long rg)
{
	return readl_relaxed(timer.base + rg);
}

static inline void keystone_timer_writel(u32 val, unsigned long rg)
{
	writel_relaxed(val, timer.base + rg);
}

/**
 * keystone_timer_barrier: write memory barrier
 * use explicit barrier to avoid using readl/writel non relaxed function
 * variants, because in our case non relaxed variants hide the true places
 * where barrier is needed.
 */
static inline void keystone_timer_barrier(void)
{
	__iowmb();
}

/**
 * keystone_timer_config: configures timer to work in oneshot/periodic modes.
 * @ mask: mask of the mode to configure
 * @ period: cycles number to configure for
 */
static int keystone_timer_config(u64 period, int mask)
{
	u32 tcr;
	u32 off;

	tcr = keystone_timer_readl(TCR);
	off = tcr & ~(TCR_ENAMODE_MASK);

	/* set enable mode */
	tcr |= mask;

	/* disable timer */
	keystone_timer_writel(off, TCR);
	/* here we have to be sure the timer has been disabled */
	keystone_timer_barrier();

	/* reset counter to zero, set new period */
	keystone_timer_writel(0, TIM12);
	keystone_timer_writel(0, TIM34);
	keystone_timer_writel(period & 0xffffffff, PRD12);
	keystone_timer_writel(period >> 32, PRD34);

	/*
	 * enable timer
	 * here we have to be sure that CNTLO, CNTHI, PRDLO, PRDHI registers
	 * have been written.
	 */
	keystone_timer_barrier();
	keystone_timer_writel(tcr, TCR);
	return 0;
}

static void keystone_timer_disable(void)
{
	u32 tcr;

	tcr = keystone_timer_readl(TCR);

	/* disable timer */
	tcr &= ~(TCR_ENAMODE_MASK);
	keystone_timer_writel(tcr, TCR);
}

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

	evt->event_handler(evt);
	return IRQ_HANDLED;
}

static int keystone_set_next_event(unsigned long cycles,
				  struct clock_event_device *evt)
{
	return keystone_timer_config(cycles, TCR_ENAMODE_ONESHOT_MASK);
}

static int keystone_shutdown(struct clock_event_device *evt)
{
	keystone_timer_disable();
	return 0;
}

static int keystone_set_periodic(struct clock_event_device *evt)
{
	keystone_timer_config(timer.hz_period, TCR_ENAMODE_PERIODIC_MASK);
	return 0;
}

static int __init keystone_timer_init(struct device_node *np)
{
	struct clock_event_device *event_dev = &timer.event_dev;
	unsigned long rate;
	struct clk *clk;
	int irq, error;

	irq  = irq_of_parse_and_map(np, 0);
	if (!irq) {
		pr_err("%s: failed to map interrupts\n", __func__);
		return -EINVAL;
	}

	timer.base = of_iomap(np, 0);
	if (!timer.base) {
		pr_err("%s: failed to map registers\n", __func__);
		return -ENXIO;
	}

	clk = of_clk_get(np, 0);
	if (IS_ERR(clk)) {
		pr_err("%s: failed to get clock\n", __func__);
		iounmap(timer.base);
		return PTR_ERR(clk);
	}

	error = clk_prepare_enable(clk);
	if (error) {
		pr_err("%s: failed to enable clock\n", __func__);
		goto err;
	}

	rate = clk_get_rate(clk);

	/* disable, use internal clock source */
	keystone_timer_writel(0, TCR);
	/* here we have to be sure the timer has been disabled */
	keystone_timer_barrier();

	/* reset timer as 64-bit, no pre-scaler, plus features are disabled */
	keystone_timer_writel(0, TGCR);

	/* unreset timer */
	keystone_timer_writel(TGCR_TIM_UNRESET_MASK, TGCR);

	/* init counter to zero */
	keystone_timer_writel(0, TIM12);
	keystone_timer_writel(0, TIM34);

	timer.hz_period = DIV_ROUND_UP(rate, HZ);

	/* enable timer interrupts */
	keystone_timer_writel(INTCTLSTAT_ENINT_MASK, INTCTLSTAT);

	error = request_irq(irq, keystone_timer_interrupt, IRQF_TIMER,
			    TIMER_NAME, event_dev);
	if (error) {
		pr_err("%s: failed to setup irq\n", __func__);
		goto err;
	}

	/* setup clockevent */
	event_dev->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT;
	event_dev->set_next_event = keystone_set_next_event;
	event_dev->set_state_shutdown = keystone_shutdown;
	event_dev->set_state_periodic = keystone_set_periodic;
	event_dev->set_state_oneshot = keystone_shutdown;
	event_dev->cpumask = cpu_possible_mask;
	event_dev->owner = THIS_MODULE;
	event_dev->name = TIMER_NAME;
	event_dev->irq = irq;

	clockevents_config_and_register(event_dev, rate, 1, ULONG_MAX);

	pr_info("keystone timer clock @%lu Hz\n", rate);
	return 0;
err:
	clk_put(clk);
	iounmap(timer.base);
	return error;
}

TIMER_OF_DECLARE(keystone_timer, "ti,keystone-timer",
			   keystone_timer_init);