1 // SPDX-License-Identifier: GPL-2.0+
2 //
3 // Copyright 2017-2019 NXP
4 
5 #include <linux/interrupt.h>
6 #include <linux/clockchips.h>
7 
8 #include "timer-of.h"
9 
10 #define CMP_OFFSET	0x10000
11 
12 #define CNTCV_LO	0x8
13 #define CNTCV_HI	0xc
14 #define CMPCV_LO	(CMP_OFFSET + 0x20)
15 #define CMPCV_HI	(CMP_OFFSET + 0x24)
16 #define CMPCR		(CMP_OFFSET + 0x2c)
17 
18 #define SYS_CTR_EN		0x1
19 #define SYS_CTR_IRQ_MASK	0x2
20 
21 #define SYS_CTR_CLK_DIV		0x3
22 
23 static void __iomem *sys_ctr_base;
24 static u32 cmpcr;
25 
26 static void sysctr_timer_enable(bool enable)
27 {
28 	writel(enable ? cmpcr | SYS_CTR_EN : cmpcr, sys_ctr_base + CMPCR);
29 }
30 
31 static void sysctr_irq_acknowledge(void)
32 {
33 	/*
34 	 * clear the enable bit(EN =0) will clear
35 	 * the status bit(ISTAT = 0), then the interrupt
36 	 * signal will be negated(acknowledged).
37 	 */
38 	sysctr_timer_enable(false);
39 }
40 
41 static inline u64 sysctr_read_counter(void)
42 {
43 	u32 cnt_hi, tmp_hi, cnt_lo;
44 
45 	do {
46 		cnt_hi = readl_relaxed(sys_ctr_base + CNTCV_HI);
47 		cnt_lo = readl_relaxed(sys_ctr_base + CNTCV_LO);
48 		tmp_hi = readl_relaxed(sys_ctr_base + CNTCV_HI);
49 	} while (tmp_hi != cnt_hi);
50 
51 	return  ((u64) cnt_hi << 32) | cnt_lo;
52 }
53 
54 static int sysctr_set_next_event(unsigned long delta,
55 				 struct clock_event_device *evt)
56 {
57 	u32 cmp_hi, cmp_lo;
58 	u64 next;
59 
60 	sysctr_timer_enable(false);
61 
62 	next = sysctr_read_counter();
63 
64 	next += delta;
65 
66 	cmp_hi = (next >> 32) & 0x00fffff;
67 	cmp_lo = next & 0xffffffff;
68 
69 	writel_relaxed(cmp_hi, sys_ctr_base + CMPCV_HI);
70 	writel_relaxed(cmp_lo, sys_ctr_base + CMPCV_LO);
71 
72 	sysctr_timer_enable(true);
73 
74 	return 0;
75 }
76 
77 static int sysctr_set_state_oneshot(struct clock_event_device *evt)
78 {
79 	return 0;
80 }
81 
82 static int sysctr_set_state_shutdown(struct clock_event_device *evt)
83 {
84 	sysctr_timer_enable(false);
85 
86 	return 0;
87 }
88 
89 static irqreturn_t sysctr_timer_interrupt(int irq, void *dev_id)
90 {
91 	struct clock_event_device *evt = dev_id;
92 
93 	sysctr_irq_acknowledge();
94 
95 	evt->event_handler(evt);
96 
97 	return IRQ_HANDLED;
98 }
99 
100 static struct timer_of to_sysctr = {
101 	.flags = TIMER_OF_IRQ | TIMER_OF_CLOCK | TIMER_OF_BASE,
102 	.clkevt = {
103 		.name			= "i.MX system counter timer",
104 		.features		= CLOCK_EVT_FEAT_ONESHOT |
105 						CLOCK_EVT_FEAT_DYNIRQ,
106 		.set_state_oneshot	= sysctr_set_state_oneshot,
107 		.set_next_event		= sysctr_set_next_event,
108 		.set_state_shutdown	= sysctr_set_state_shutdown,
109 		.rating			= 200,
110 	},
111 	.of_irq = {
112 		.handler		= sysctr_timer_interrupt,
113 		.flags			= IRQF_TIMER | IRQF_IRQPOLL,
114 	},
115 	.of_clk = {
116 		.name = "per",
117 	},
118 };
119 
120 static void __init sysctr_clockevent_init(void)
121 {
122 	to_sysctr.clkevt.cpumask = cpumask_of(0);
123 
124 	clockevents_config_and_register(&to_sysctr.clkevt,
125 					timer_of_rate(&to_sysctr),
126 					0xff, 0x7fffffff);
127 }
128 
129 static int __init sysctr_timer_init(struct device_node *np)
130 {
131 	int ret = 0;
132 
133 	ret = timer_of_init(np, &to_sysctr);
134 	if (ret)
135 		return ret;
136 
137 	/* system counter clock is divided by 3 internally */
138 	to_sysctr.of_clk.rate /= SYS_CTR_CLK_DIV;
139 
140 	sys_ctr_base = timer_of_base(&to_sysctr);
141 	cmpcr = readl(sys_ctr_base + CMPCR);
142 	cmpcr &= ~SYS_CTR_EN;
143 
144 	sysctr_clockevent_init();
145 
146 	return 0;
147 }
148 TIMER_OF_DECLARE(sysctr_timer, "nxp,sysctr-timer", sysctr_timer_init);
149