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Daniel Tang77ba83b2013-06-01 16:02:37 +10001/*
2 * linux/drivers/clocksource/zevio-timer.c
3 *
4 * Copyright (C) 2013 Daniel Tang <tangrs@tangrs.id.au>
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2, as
8 * published by the Free Software Foundation.
9 *
10 */
11
12#include <linux/io.h>
13#include <linux/irq.h>
14#include <linux/of.h>
15#include <linux/of_address.h>
16#include <linux/of_irq.h>
17#include <linux/clk.h>
18#include <linux/clockchips.h>
19#include <linux/cpumask.h>
20#include <linux/interrupt.h>
21#include <linux/slab.h>
22
23#define IO_CURRENT_VAL 0x00
24#define IO_DIVIDER 0x04
25#define IO_CONTROL 0x08
26
27#define IO_TIMER1 0x00
28#define IO_TIMER2 0x0C
29
30#define IO_MATCH_BEGIN 0x18
31#define IO_MATCH(x) (IO_MATCH_BEGIN + ((x) << 2))
32
33#define IO_INTR_STS 0x00
34#define IO_INTR_ACK 0x00
35#define IO_INTR_MSK 0x04
36
37#define CNTL_STOP_TIMER (1 << 4)
38#define CNTL_RUN_TIMER (0 << 4)
39
40#define CNTL_INC (1 << 3)
41#define CNTL_DEC (0 << 3)
42
43#define CNTL_TOZERO 0
44#define CNTL_MATCH(x) ((x) + 1)
45#define CNTL_FOREVER 7
46
47/* There are 6 match registers but we only use one. */
48#define TIMER_MATCH 0
49
50#define TIMER_INTR_MSK (1 << (TIMER_MATCH))
51#define TIMER_INTR_ALL 0x3F
52
53struct zevio_timer {
54 void __iomem *base;
55 void __iomem *timer1, *timer2;
56 void __iomem *interrupt_regs;
57
58 struct clk *clk;
59 struct clock_event_device clkevt;
60 struct irqaction clkevt_irq;
61
62 char clocksource_name[64];
63 char clockevent_name[64];
64};
65
66static int zevio_timer_set_event(unsigned long delta,
67 struct clock_event_device *dev)
68{
69 struct zevio_timer *timer = container_of(dev, struct zevio_timer,
70 clkevt);
71
72 writel(delta, timer->timer1 + IO_CURRENT_VAL);
73 writel(CNTL_RUN_TIMER | CNTL_DEC | CNTL_MATCH(TIMER_MATCH),
74 timer->timer1 + IO_CONTROL);
75
76 return 0;
77}
78
79static void zevio_timer_set_mode(enum clock_event_mode mode,
80 struct clock_event_device *dev)
81{
82 struct zevio_timer *timer = container_of(dev, struct zevio_timer,
83 clkevt);
84
85 switch (mode) {
86 case CLOCK_EVT_MODE_RESUME:
87 case CLOCK_EVT_MODE_ONESHOT:
88 /* Enable timer interrupts */
89 writel(TIMER_INTR_MSK, timer->interrupt_regs + IO_INTR_MSK);
90 writel(TIMER_INTR_ALL, timer->interrupt_regs + IO_INTR_ACK);
91 break;
92 case CLOCK_EVT_MODE_SHUTDOWN:
93 case CLOCK_EVT_MODE_UNUSED:
94 /* Disable timer interrupts */
95 writel(0, timer->interrupt_regs + IO_INTR_MSK);
96 writel(TIMER_INTR_ALL, timer->interrupt_regs + IO_INTR_ACK);
97 /* Stop timer */
98 writel(CNTL_STOP_TIMER, timer->timer1 + IO_CONTROL);
99 break;
100 case CLOCK_EVT_MODE_PERIODIC:
101 default:
102 /* Unsupported */
103 break;
104 }
105}
106
107static irqreturn_t zevio_timer_interrupt(int irq, void *dev_id)
108{
109 struct zevio_timer *timer = dev_id;
110 u32 intr;
111
112 intr = readl(timer->interrupt_regs + IO_INTR_ACK);
113 if (!(intr & TIMER_INTR_MSK))
114 return IRQ_NONE;
115
116 writel(TIMER_INTR_MSK, timer->interrupt_regs + IO_INTR_ACK);
117 writel(CNTL_STOP_TIMER, timer->timer1 + IO_CONTROL);
118
119 if (timer->clkevt.event_handler)
120 timer->clkevt.event_handler(&timer->clkevt);
121
122 return IRQ_HANDLED;
123}
124
125static int __init zevio_timer_add(struct device_node *node)
126{
127 struct zevio_timer *timer;
128 struct resource res;
129 int irqnr, ret;
130
131 timer = kzalloc(sizeof(*timer), GFP_KERNEL);
132 if (!timer)
133 return -ENOMEM;
134
135 timer->base = of_iomap(node, 0);
136 if (!timer->base) {
137 ret = -EINVAL;
138 goto error_free;
139 }
140 timer->timer1 = timer->base + IO_TIMER1;
141 timer->timer2 = timer->base + IO_TIMER2;
142
143 timer->clk = of_clk_get(node, 0);
144 if (IS_ERR(timer->clk)) {
145 ret = PTR_ERR(timer->clk);
146 pr_err("Timer clock not found! (error %d)\n", ret);
147 goto error_unmap;
148 }
149
150 timer->interrupt_regs = of_iomap(node, 1);
151 irqnr = irq_of_parse_and_map(node, 0);
152
153 of_address_to_resource(node, 0, &res);
154 scnprintf(timer->clocksource_name, sizeof(timer->clocksource_name),
155 "%llx.%s_clocksource",
156 (unsigned long long)res.start, node->name);
157
158 scnprintf(timer->clockevent_name, sizeof(timer->clockevent_name),
159 "%llx.%s_clockevent",
160 (unsigned long long)res.start, node->name);
161
162 if (timer->interrupt_regs && irqnr) {
163 timer->clkevt.name = timer->clockevent_name;
164 timer->clkevt.set_next_event = zevio_timer_set_event;
165 timer->clkevt.set_mode = zevio_timer_set_mode;
166 timer->clkevt.rating = 200;
167 timer->clkevt.cpumask = cpu_all_mask;
168 timer->clkevt.features = CLOCK_EVT_FEAT_ONESHOT;
169 timer->clkevt.irq = irqnr;
170
171 writel(CNTL_STOP_TIMER, timer->timer1 + IO_CONTROL);
172 writel(0, timer->timer1 + IO_DIVIDER);
173
174 /* Start with timer interrupts disabled */
175 writel(0, timer->interrupt_regs + IO_INTR_MSK);
176 writel(TIMER_INTR_ALL, timer->interrupt_regs + IO_INTR_ACK);
177
178 /* Interrupt to occur when timer value matches 0 */
179 writel(0, timer->base + IO_MATCH(TIMER_MATCH));
180
181 timer->clkevt_irq.name = timer->clockevent_name;
182 timer->clkevt_irq.handler = zevio_timer_interrupt;
183 timer->clkevt_irq.dev_id = timer;
184 timer->clkevt_irq.flags = IRQF_TIMER | IRQF_IRQPOLL;
185
186 setup_irq(irqnr, &timer->clkevt_irq);
187
188 clockevents_config_and_register(&timer->clkevt,
189 clk_get_rate(timer->clk), 0x0001, 0xffff);
190 pr_info("Added %s as clockevent\n", timer->clockevent_name);
191 }
192
193 writel(CNTL_STOP_TIMER, timer->timer2 + IO_CONTROL);
194 writel(0, timer->timer2 + IO_CURRENT_VAL);
195 writel(0, timer->timer2 + IO_DIVIDER);
196 writel(CNTL_RUN_TIMER | CNTL_FOREVER | CNTL_INC,
197 timer->timer2 + IO_CONTROL);
198
199 clocksource_mmio_init(timer->timer2 + IO_CURRENT_VAL,
200 timer->clocksource_name,
201 clk_get_rate(timer->clk),
202 200, 16,
203 clocksource_mmio_readw_up);
204
205 pr_info("Added %s as clocksource\n", timer->clocksource_name);
206
207 return 0;
208error_unmap:
209 iounmap(timer->base);
210error_free:
211 kfree(timer);
212 return ret;
213}
214
Alexander Shiyan9afa27c2014-04-26 09:32:16 +0400215static void __init zevio_timer_init(struct device_node *node)
216{
217 BUG_ON(zevio_timer_add(node));
218}
219
220CLOCKSOURCE_OF_DECLARE(zevio_timer, "lsi,zevio-timer", zevio_timer_init);