1/*
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 int zevio_timer_shutdown(struct clock_event_device *dev)
80{
81 struct zevio_timer *timer = container_of(dev, struct zevio_timer,
82 clkevt);
83
84 /* Disable timer interrupts */
85 writel(0, timer->interrupt_regs + IO_INTR_MSK);
86 writel(TIMER_INTR_ALL, timer->interrupt_regs + IO_INTR_ACK);
87 /* Stop timer */
88 writel(CNTL_STOP_TIMER, timer->timer1 + IO_CONTROL);
89 return 0;
90}
91
92static int zevio_timer_set_oneshot(struct clock_event_device *dev)
93{
94 struct zevio_timer *timer = container_of(dev, struct zevio_timer,
95 clkevt);
96
97 /* Enable timer interrupts */
98 writel(TIMER_INTR_MSK, timer->interrupt_regs + IO_INTR_MSK);
99 writel(TIMER_INTR_ALL, timer->interrupt_regs + IO_INTR_ACK);
100 return 0;
101}
102
103static irqreturn_t zevio_timer_interrupt(int irq, void *dev_id)
104{
105 struct zevio_timer *timer = dev_id;
106 u32 intr;
107
108 intr = readl(timer->interrupt_regs + IO_INTR_ACK);
109 if (!(intr & TIMER_INTR_MSK))
110 return IRQ_NONE;
111
112 writel(TIMER_INTR_MSK, timer->interrupt_regs + IO_INTR_ACK);
113 writel(CNTL_STOP_TIMER, timer->timer1 + IO_CONTROL);
114
115 if (timer->clkevt.event_handler)
116 timer->clkevt.event_handler(&timer->clkevt);
117
118 return IRQ_HANDLED;
119}
120
121static int __init zevio_timer_add(struct device_node *node)
122{
123 struct zevio_timer *timer;
124 struct resource res;
125 int irqnr, ret;
126
127 timer = kzalloc(sizeof(*timer), GFP_KERNEL);
128 if (!timer)
129 return -ENOMEM;
130
131 timer->base = of_iomap(node, 0);
132 if (!timer->base) {
133 ret = -EINVAL;
134 goto error_free;
135 }
136 timer->timer1 = timer->base + IO_TIMER1;
137 timer->timer2 = timer->base + IO_TIMER2;
138
139 timer->clk = of_clk_get(node, 0);
140 if (IS_ERR(timer->clk)) {
141 ret = PTR_ERR(timer->clk);
142 pr_err("Timer clock not found! (error %d)\n", ret);
143 goto error_unmap;
144 }
145
146 timer->interrupt_regs = of_iomap(node, 1);
147 irqnr = irq_of_parse_and_map(node, 0);
148
149 of_address_to_resource(node, 0, &res);
150 scnprintf(timer->clocksource_name, sizeof(timer->clocksource_name),
151 "%llx.%pOFn_clocksource",
152 (unsigned long long)res.start, node);
153
154 scnprintf(timer->clockevent_name, sizeof(timer->clockevent_name),
155 "%llx.%pOFn_clockevent",
156 (unsigned long long)res.start, node);
157
158 if (timer->interrupt_regs && irqnr) {
159 timer->clkevt.name = timer->clockevent_name;
160 timer->clkevt.set_next_event = zevio_timer_set_event;
161 timer->clkevt.set_state_shutdown = zevio_timer_shutdown;
162 timer->clkevt.set_state_oneshot = zevio_timer_set_oneshot;
163 timer->clkevt.tick_resume = zevio_timer_set_oneshot;
164 timer->clkevt.rating = 200;
165 timer->clkevt.cpumask = cpu_possible_mask;
166 timer->clkevt.features = CLOCK_EVT_FEAT_ONESHOT;
167 timer->clkevt.irq = irqnr;
168
169 writel(CNTL_STOP_TIMER, timer->timer1 + IO_CONTROL);
170 writel(0, timer->timer1 + IO_DIVIDER);
171
172 /* Start with timer interrupts disabled */
173 writel(0, timer->interrupt_regs + IO_INTR_MSK);
174 writel(TIMER_INTR_ALL, timer->interrupt_regs + IO_INTR_ACK);
175
176 /* Interrupt to occur when timer value matches 0 */
177 writel(0, timer->base + IO_MATCH(TIMER_MATCH));
178
179 timer->clkevt_irq.name = timer->clockevent_name;
180 timer->clkevt_irq.handler = zevio_timer_interrupt;
181 timer->clkevt_irq.dev_id = timer;
182 timer->clkevt_irq.flags = IRQF_TIMER | IRQF_IRQPOLL;
183
184 setup_irq(irqnr, &timer->clkevt_irq);
185
186 clockevents_config_and_register(&timer->clkevt,
187 clk_get_rate(timer->clk), 0x0001, 0xffff);
188 pr_info("Added %s as clockevent\n", timer->clockevent_name);
189 }
190
191 writel(CNTL_STOP_TIMER, timer->timer2 + IO_CONTROL);
192 writel(0, timer->timer2 + IO_CURRENT_VAL);
193 writel(0, timer->timer2 + IO_DIVIDER);
194 writel(CNTL_RUN_TIMER | CNTL_FOREVER | CNTL_INC,
195 timer->timer2 + IO_CONTROL);
196
197 clocksource_mmio_init(timer->timer2 + IO_CURRENT_VAL,
198 timer->clocksource_name,
199 clk_get_rate(timer->clk),
200 200, 16,
201 clocksource_mmio_readw_up);
202
203 pr_info("Added %s as clocksource\n", timer->clocksource_name);
204
205 return 0;
206error_unmap:
207 iounmap(timer->base);
208error_free:
209 kfree(timer);
210 return ret;
211}
212
213static int __init zevio_timer_init(struct device_node *node)
214{
215 return zevio_timer_add(node);
216}
217
218TIMER_OF_DECLARE(zevio_timer, "lsi,zevio-timer", zevio_timer_init);
219