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  */
50 static 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 
58 static 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 
65 static 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 
71 static 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 
85 static 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 
94 static 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 
104 static 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 
115 static 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 
127 static void sun4i_timer_clear_interrupt(void __iomem *base)
128 {
129 	writel(TIMER_IRQ_EN(0), base + TIMER_IRQ_ST_REG);
130 }
131 
132 static 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 
143 static 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 
164 static u64 notrace sun4i_timer_sched_read(void)
165 {
166 	return ~readl(timer_of_base(&to) + TIMER_CNTVAL_REG(1));
167 }
168 
169 static 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 	    of_machine_is_compatible("allwinner,suniv-f1c100s"))
191 		sched_clock_register(sun4i_timer_sched_read, 32,
192 				     timer_of_rate(&to));
193 
194 	ret = clocksource_mmio_init(timer_of_base(&to) + TIMER_CNTVAL_REG(1),
195 				    node->name, timer_of_rate(&to), 350, 32,
196 				    clocksource_mmio_readl_down);
197 	if (ret) {
198 		pr_err("Failed to register clocksource\n");
199 		return ret;
200 	}
201 
202 	writel(TIMER_CTL_CLK_SRC(TIMER_CTL_CLK_SRC_OSC24M),
203 	       timer_of_base(&to) + TIMER_CTL_REG(0));
204 
205 	/* Make sure timer is stopped before playing with interrupts */
206 	sun4i_clkevt_time_stop(timer_of_base(&to), 0);
207 
208 	/* clear timer0 interrupt */
209 	sun4i_timer_clear_interrupt(timer_of_base(&to));
210 
211 	clockevents_config_and_register(&to.clkevt, timer_of_rate(&to),
212 					TIMER_SYNC_TICKS, 0xffffffff);
213 
214 	/* Enable timer0 interrupt */
215 	val = readl(timer_of_base(&to) + TIMER_IRQ_EN_REG);
216 	writel(val | TIMER_IRQ_EN(0), timer_of_base(&to) + TIMER_IRQ_EN_REG);
217 
218 	return ret;
219 }
220 TIMER_OF_DECLARE(sun4i, "allwinner,sun4i-a10-timer",
221 		       sun4i_timer_init);
222 TIMER_OF_DECLARE(suniv, "allwinner,suniv-f1c100s-timer",
223 		       sun4i_timer_init);
224