1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Allwinner A1X SoCs timer handling.
4  *
5  * Copyright (C) 2012 Maxime Ripard
6  *
7  * Maxime Ripard <maxime.ripard@free-electrons.com>
8  *
9  * Based on code from
10  * Allwinner Technology Co., Ltd. <www.allwinnertech.com>
11  * Benn Huang <benn@allwinnertech.com>
12  */
13 
14 #include <linux/clk.h>
15 #include <linux/clockchips.h>
16 #include <linux/interrupt.h>
17 #include <linux/irq.h>
18 #include <linux/irqreturn.h>
19 #include <linux/sched_clock.h>
20 #include <linux/of.h>
21 #include <linux/of_address.h>
22 #include <linux/of_irq.h>
23 
24 #include "timer-of.h"
25 
26 #define TIMER_IRQ_EN_REG	0x00
27 #define TIMER_IRQ_EN(val)		BIT(val)
28 #define TIMER_IRQ_ST_REG	0x04
29 #define TIMER_IRQ_CLEAR(val)		BIT(val)
30 #define TIMER_CTL_REG(val)	(0x10 * val + 0x10)
31 #define TIMER_CTL_ENABLE		BIT(0)
32 #define TIMER_CTL_RELOAD		BIT(1)
33 #define TIMER_CTL_CLK_SRC(val)		(((val) & 0x3) << 2)
34 #define TIMER_CTL_CLK_SRC_OSC24M		(1)
35 #define TIMER_CTL_CLK_PRES(val)		(((val) & 0x7) << 4)
36 #define TIMER_CTL_ONESHOT		BIT(7)
37 #define TIMER_INTVAL_REG(val)	(0x10 * (val) + 0x14)
38 #define TIMER_CNTVAL_REG(val)	(0x10 * (val) + 0x18)
39 
40 #define TIMER_SYNC_TICKS	3
41 
42 /*
43  * When we disable a timer, we need to wait at least for 2 cycles of
44  * the timer source clock. We will use for that the clocksource timer
45  * that is already setup and runs at the same frequency than the other
46  * timers, and we never will be disabled.
47  */
48 static void sun4i_clkevt_sync(void __iomem *base)
49 {
50 	u32 old = readl(base + TIMER_CNTVAL_REG(1));
51 
52 	while ((old - readl(base + TIMER_CNTVAL_REG(1))) < TIMER_SYNC_TICKS)
53 		cpu_relax();
54 }
55 
56 static void sun4i_clkevt_time_stop(void __iomem *base, u8 timer)
57 {
58 	u32 val = readl(base + TIMER_CTL_REG(timer));
59 	writel(val & ~TIMER_CTL_ENABLE, base + TIMER_CTL_REG(timer));
60 	sun4i_clkevt_sync(base);
61 }
62 
63 static void sun4i_clkevt_time_setup(void __iomem *base, u8 timer,
64 				    unsigned long delay)
65 {
66 	writel(delay, base + TIMER_INTVAL_REG(timer));
67 }
68 
69 static void sun4i_clkevt_time_start(void __iomem *base, u8 timer,
70 				    bool periodic)
71 {
72 	u32 val = readl(base + TIMER_CTL_REG(timer));
73 
74 	if (periodic)
75 		val &= ~TIMER_CTL_ONESHOT;
76 	else
77 		val |= TIMER_CTL_ONESHOT;
78 
79 	writel(val | TIMER_CTL_ENABLE | TIMER_CTL_RELOAD,
80 	       base + TIMER_CTL_REG(timer));
81 }
82 
83 static int sun4i_clkevt_shutdown(struct clock_event_device *evt)
84 {
85 	struct timer_of *to = to_timer_of(evt);
86 
87 	sun4i_clkevt_time_stop(timer_of_base(to), 0);
88 
89 	return 0;
90 }
91 
92 static int sun4i_clkevt_set_oneshot(struct clock_event_device *evt)
93 {
94 	struct timer_of *to = to_timer_of(evt);
95 
96 	sun4i_clkevt_time_stop(timer_of_base(to), 0);
97 	sun4i_clkevt_time_start(timer_of_base(to), 0, false);
98 
99 	return 0;
100 }
101 
102 static int sun4i_clkevt_set_periodic(struct clock_event_device *evt)
103 {
104 	struct timer_of *to = to_timer_of(evt);
105 
106 	sun4i_clkevt_time_stop(timer_of_base(to), 0);
107 	sun4i_clkevt_time_setup(timer_of_base(to), 0, timer_of_period(to));
108 	sun4i_clkevt_time_start(timer_of_base(to), 0, true);
109 
110 	return 0;
111 }
112 
113 static int sun4i_clkevt_next_event(unsigned long evt,
114 				   struct clock_event_device *clkevt)
115 {
116 	struct timer_of *to = to_timer_of(clkevt);
117 
118 	sun4i_clkevt_time_stop(timer_of_base(to), 0);
119 	sun4i_clkevt_time_setup(timer_of_base(to), 0, evt - TIMER_SYNC_TICKS);
120 	sun4i_clkevt_time_start(timer_of_base(to), 0, false);
121 
122 	return 0;
123 }
124 
125 static void sun4i_timer_clear_interrupt(void __iomem *base)
126 {
127 	writel(TIMER_IRQ_CLEAR(0), base + TIMER_IRQ_ST_REG);
128 }
129 
130 static irqreturn_t sun4i_timer_interrupt(int irq, void *dev_id)
131 {
132 	struct clock_event_device *evt = dev_id;
133 	struct timer_of *to = to_timer_of(evt);
134 
135 	sun4i_timer_clear_interrupt(timer_of_base(to));
136 	evt->event_handler(evt);
137 
138 	return IRQ_HANDLED;
139 }
140 
141 static struct timer_of to = {
142 	.flags = TIMER_OF_IRQ | TIMER_OF_CLOCK | TIMER_OF_BASE,
143 
144 	.clkevt = {
145 		.name = "sun4i_tick",
146 		.rating = 350,
147 		.features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
148 		.set_state_shutdown = sun4i_clkevt_shutdown,
149 		.set_state_periodic = sun4i_clkevt_set_periodic,
150 		.set_state_oneshot = sun4i_clkevt_set_oneshot,
151 		.tick_resume = sun4i_clkevt_shutdown,
152 		.set_next_event = sun4i_clkevt_next_event,
153 		.cpumask = cpu_possible_mask,
154 	},
155 
156 	.of_irq = {
157 		.handler = sun4i_timer_interrupt,
158 		.flags = IRQF_TIMER | IRQF_IRQPOLL,
159 	},
160 };
161 
162 static u64 notrace sun4i_timer_sched_read(void)
163 {
164 	return ~readl(timer_of_base(&to) + TIMER_CNTVAL_REG(1));
165 }
166 
167 static int __init sun4i_timer_init(struct device_node *node)
168 {
169 	int ret;
170 	u32 val;
171 
172 	ret = timer_of_init(node, &to);
173 	if (ret)
174 		return ret;
175 
176 	writel(~0, timer_of_base(&to) + TIMER_INTVAL_REG(1));
177 	writel(TIMER_CTL_ENABLE | TIMER_CTL_RELOAD |
178 	       TIMER_CTL_CLK_SRC(TIMER_CTL_CLK_SRC_OSC24M),
179 	       timer_of_base(&to) + TIMER_CTL_REG(1));
180 
181 	/*
182 	 * sched_clock_register does not have priorities, and on sun6i and
183 	 * later there is a better sched_clock registered by arm_arch_timer.c
184 	 */
185 	if (of_machine_is_compatible("allwinner,sun4i-a10") ||
186 	    of_machine_is_compatible("allwinner,sun5i-a13") ||
187 	    of_machine_is_compatible("allwinner,sun5i-a10s") ||
188 	    of_machine_is_compatible("allwinner,suniv-f1c100s"))
189 		sched_clock_register(sun4i_timer_sched_read, 32,
190 				     timer_of_rate(&to));
191 
192 	ret = clocksource_mmio_init(timer_of_base(&to) + TIMER_CNTVAL_REG(1),
193 				    node->name, timer_of_rate(&to), 350, 32,
194 				    clocksource_mmio_readl_down);
195 	if (ret) {
196 		pr_err("Failed to register clocksource\n");
197 		return ret;
198 	}
199 
200 	writel(TIMER_CTL_CLK_SRC(TIMER_CTL_CLK_SRC_OSC24M),
201 	       timer_of_base(&to) + TIMER_CTL_REG(0));
202 
203 	/* Make sure timer is stopped before playing with interrupts */
204 	sun4i_clkevt_time_stop(timer_of_base(&to), 0);
205 
206 	/* clear timer0 interrupt */
207 	sun4i_timer_clear_interrupt(timer_of_base(&to));
208 
209 	clockevents_config_and_register(&to.clkevt, timer_of_rate(&to),
210 					TIMER_SYNC_TICKS, 0xffffffff);
211 
212 	/* Enable timer0 interrupt */
213 	val = readl(timer_of_base(&to) + TIMER_IRQ_EN_REG);
214 	writel(val | TIMER_IRQ_EN(0), timer_of_base(&to) + TIMER_IRQ_EN_REG);
215 
216 	return ret;
217 }
218 TIMER_OF_DECLARE(sun4i, "allwinner,sun4i-a10-timer",
219 		       sun4i_timer_init);
220 TIMER_OF_DECLARE(sun8i_a23, "allwinner,sun8i-a23-timer",
221 		 sun4i_timer_init);
222 TIMER_OF_DECLARE(sun8i_v3s, "allwinner,sun8i-v3s-timer",
223 		 sun4i_timer_init);
224 TIMER_OF_DECLARE(suniv, "allwinner,suniv-f1c100s-timer",
225 		       sun4i_timer_init);
226