1/*
2 * Allwinner A1X SoCs timer handling.
3 *
4 * Copyright (C) 2012 Maxime Ripard
5 *
6 * Maxime Ripard <maxime.ripard@free-electrons.com>
7 *
8 * Based on code from
9 * Allwinner Technology Co., Ltd. <www.allwinnertech.com>
10 * Benn Huang <benn@allwinnertech.com>
11 *
12 * This file is licensed under the terms of the GNU General Public
13 * License version 2. This program is licensed "as is" without any
14 * warranty of any kind, whether express or implied.
15 */
16
17#include <linux/clk.h>
18#include <linux/clockchips.h>
19#include <linux/interrupt.h>
20#include <linux/irq.h>
21#include <linux/irqreturn.h>
22#include <linux/sched_clock.h>
23#include <linux/of.h>
24#include <linux/of_address.h>
25#include <linux/of_irq.h>
26
27#include "timer-of.h"
28
29#define TIMER_IRQ_EN_REG 0x00
30#define TIMER_IRQ_EN(val) BIT(val)
31#define TIMER_IRQ_ST_REG 0x04
32#define TIMER_CTL_REG(val) (0x10 * val + 0x10)
33#define TIMER_CTL_ENABLE BIT(0)
34#define TIMER_CTL_RELOAD BIT(1)
35#define TIMER_CTL_CLK_SRC(val) (((val) & 0x3) << 2)
36#define TIMER_CTL_CLK_SRC_OSC24M (1)
37#define TIMER_CTL_CLK_PRES(val) (((val) & 0x7) << 4)
38#define TIMER_CTL_ONESHOT BIT(7)
39#define TIMER_INTVAL_REG(val) (0x10 * (val) + 0x14)
40#define TIMER_CNTVAL_REG(val) (0x10 * (val) + 0x18)
41
42#define TIMER_SYNC_TICKS 3
43
44/*
45 * When we disable a timer, we need to wait at least for 2 cycles of
46 * the timer source clock. We will use for that the clocksource timer
47 * that is already setup and runs at the same frequency than the other
48 * timers, and we never will be disabled.
49 */
50static void sun4i_clkevt_sync(void __iomem *base)
51{
52 u32 old = readl(base + TIMER_CNTVAL_REG(1));
53
54 while ((old - readl(base + TIMER_CNTVAL_REG(1))) < TIMER_SYNC_TICKS)
55 cpu_relax();
56}
57
58static void sun4i_clkevt_time_stop(void __iomem *base, u8 timer)
59{
60 u32 val = readl(base + TIMER_CTL_REG(timer));
61 writel(val & ~TIMER_CTL_ENABLE, base + TIMER_CTL_REG(timer));
62 sun4i_clkevt_sync(base);
63}
64
65static void sun4i_clkevt_time_setup(void __iomem *base, u8 timer,
66 unsigned long delay)
67{
68 writel(delay, base + TIMER_INTVAL_REG(timer));
69}
70
71static void sun4i_clkevt_time_start(void __iomem *base, u8 timer,
72 bool periodic)
73{
74 u32 val = readl(base + TIMER_CTL_REG(timer));
75
76 if (periodic)
77 val &= ~TIMER_CTL_ONESHOT;
78 else
79 val |= TIMER_CTL_ONESHOT;
80
81 writel(val | TIMER_CTL_ENABLE | TIMER_CTL_RELOAD,
82 base + TIMER_CTL_REG(timer));
83}
84
85static int sun4i_clkevt_shutdown(struct clock_event_device *evt)
86{
87 struct timer_of *to = to_timer_of(evt);
88
89 sun4i_clkevt_time_stop(timer_of_base(to), 0);
90
91 return 0;
92}
93
94static int sun4i_clkevt_set_oneshot(struct clock_event_device *evt)
95{
96 struct timer_of *to = to_timer_of(evt);
97
98 sun4i_clkevt_time_stop(timer_of_base(to), 0);
99 sun4i_clkevt_time_start(timer_of_base(to), 0, false);
100
101 return 0;
102}
103
104static int sun4i_clkevt_set_periodic(struct clock_event_device *evt)
105{
106 struct timer_of *to = to_timer_of(evt);
107
108 sun4i_clkevt_time_stop(timer_of_base(to), 0);
109 sun4i_clkevt_time_setup(timer_of_base(to), 0, timer_of_period(to));
110 sun4i_clkevt_time_start(timer_of_base(to), 0, true);
111
112 return 0;
113}
114
115static int sun4i_clkevt_next_event(unsigned long evt,
116 struct clock_event_device *clkevt)
117{
118 struct timer_of *to = to_timer_of(clkevt);
119
120 sun4i_clkevt_time_stop(timer_of_base(to), 0);
121 sun4i_clkevt_time_setup(timer_of_base(to), 0, evt - TIMER_SYNC_TICKS);
122 sun4i_clkevt_time_start(timer_of_base(to), 0, false);
123
124 return 0;
125}
126
127static void sun4i_timer_clear_interrupt(void __iomem *base)
128{
129 writel(TIMER_IRQ_EN(0), base + TIMER_IRQ_ST_REG);
130}
131
132static irqreturn_t sun4i_timer_interrupt(int irq, void *dev_id)
133{
134 struct clock_event_device *evt = (struct clock_event_device *)dev_id;
135 struct timer_of *to = to_timer_of(evt);
136
137 sun4i_timer_clear_interrupt(timer_of_base(to));
138 evt->event_handler(evt);
139
140 return IRQ_HANDLED;
141}
142
143static struct timer_of to = {
144 .flags = TIMER_OF_IRQ | TIMER_OF_CLOCK | TIMER_OF_BASE,
145
146 .clkevt = {
147 .name = "sun4i_tick",
148 .rating = 350,
149 .features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
150 .set_state_shutdown = sun4i_clkevt_shutdown,
151 .set_state_periodic = sun4i_clkevt_set_periodic,
152 .set_state_oneshot = sun4i_clkevt_set_oneshot,
153 .tick_resume = sun4i_clkevt_shutdown,
154 .set_next_event = sun4i_clkevt_next_event,
155 .cpumask = cpu_possible_mask,
156 },
157
158 .of_irq = {
159 .handler = sun4i_timer_interrupt,
160 .flags = IRQF_TIMER | IRQF_IRQPOLL,
161 },
162};
163
164static u64 notrace sun4i_timer_sched_read(void)
165{
166 return ~readl(timer_of_base(&to) + TIMER_CNTVAL_REG(1));
167}
168
169static int __init sun4i_timer_init(struct device_node *node)
170{
171 int ret;
172 u32 val;
173
174 ret = timer_of_init(node, &to);
175 if (ret)
176 return ret;
177
178 writel(~0, timer_of_base(&to) + TIMER_INTVAL_REG(1));
179 writel(TIMER_CTL_ENABLE | TIMER_CTL_RELOAD |
180 TIMER_CTL_CLK_SRC(TIMER_CTL_CLK_SRC_OSC24M),
181 timer_of_base(&to) + TIMER_CTL_REG(1));
182
183 /*
184 * sched_clock_register does not have priorities, and on sun6i and
185 * later there is a better sched_clock registered by arm_arch_timer.c
186 */
187 if (of_machine_is_compatible("allwinner,sun4i-a10") ||
188 of_machine_is_compatible("allwinner,sun5i-a13") ||
189 of_machine_is_compatible("allwinner,sun5i-a10s"))
190 sched_clock_register(sun4i_timer_sched_read, 32,
191 timer_of_rate(&to));
192
193 ret = clocksource_mmio_init(timer_of_base(&to) + TIMER_CNTVAL_REG(1),
194 node->name, timer_of_rate(&to), 350, 32,
195 clocksource_mmio_readl_down);
196 if (ret) {
197 pr_err("Failed to register clocksource\n");
198 return ret;
199 }
200
201 writel(TIMER_CTL_CLK_SRC(TIMER_CTL_CLK_SRC_OSC24M),
202 timer_of_base(&to) + TIMER_CTL_REG(0));
203
204 /* Make sure timer is stopped before playing with interrupts */
205 sun4i_clkevt_time_stop(timer_of_base(&to), 0);
206
207 /* clear timer0 interrupt */
208 sun4i_timer_clear_interrupt(timer_of_base(&to));
209
210 clockevents_config_and_register(&to.clkevt, timer_of_rate(&to),
211 TIMER_SYNC_TICKS, 0xffffffff);
212
213 /* Enable timer0 interrupt */
214 val = readl(timer_of_base(&to) + TIMER_IRQ_EN_REG);
215 writel(val | TIMER_IRQ_EN(0), timer_of_base(&to) + TIMER_IRQ_EN_REG);
216
217 return ret;
218}
219TIMER_OF_DECLARE(sun4i, "allwinner,sun4i-a10-timer",
220 sun4i_timer_init);
221