Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
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#include <linux/of_address.h>
8#include <linux/of_irq.h>
9
10#include "timer-of.h"
11
12#define CMP_OFFSET 0x10000
13
14#define CNTCV_LO 0x8
15#define CNTCV_HI 0xc
16#define CMPCV_LO (CMP_OFFSET + 0x20)
17#define CMPCV_HI (CMP_OFFSET + 0x24)
18#define CMPCR (CMP_OFFSET + 0x2c)
19
20#define SYS_CTR_EN 0x1
21#define SYS_CTR_IRQ_MASK 0x2
22
23#define SYS_CTR_CLK_DIV 0x3
24
25static void __iomem *sys_ctr_base;
26static u32 cmpcr;
27
28static void sysctr_timer_enable(bool enable)
29{
30 writel(enable ? cmpcr | SYS_CTR_EN : cmpcr, sys_ctr_base + CMPCR);
31}
32
33static void sysctr_irq_acknowledge(void)
34{
35 /*
36 * clear the enable bit(EN =0) will clear
37 * the status bit(ISTAT = 0), then the interrupt
38 * signal will be negated(acknowledged).
39 */
40 sysctr_timer_enable(false);
41}
42
43static inline u64 sysctr_read_counter(void)
44{
45 u32 cnt_hi, tmp_hi, cnt_lo;
46
47 do {
48 cnt_hi = readl_relaxed(sys_ctr_base + CNTCV_HI);
49 cnt_lo = readl_relaxed(sys_ctr_base + CNTCV_LO);
50 tmp_hi = readl_relaxed(sys_ctr_base + CNTCV_HI);
51 } while (tmp_hi != cnt_hi);
52
53 return ((u64) cnt_hi << 32) | cnt_lo;
54}
55
56static int sysctr_set_next_event(unsigned long delta,
57 struct clock_event_device *evt)
58{
59 u32 cmp_hi, cmp_lo;
60 u64 next;
61
62 sysctr_timer_enable(false);
63
64 next = sysctr_read_counter();
65
66 next += delta;
67
68 cmp_hi = (next >> 32) & 0x00fffff;
69 cmp_lo = next & 0xffffffff;
70
71 writel_relaxed(cmp_hi, sys_ctr_base + CMPCV_HI);
72 writel_relaxed(cmp_lo, sys_ctr_base + CMPCV_LO);
73
74 sysctr_timer_enable(true);
75
76 return 0;
77}
78
79static int sysctr_set_state_oneshot(struct clock_event_device *evt)
80{
81 return 0;
82}
83
84static int sysctr_set_state_shutdown(struct clock_event_device *evt)
85{
86 sysctr_timer_enable(false);
87
88 return 0;
89}
90
91static irqreturn_t sysctr_timer_interrupt(int irq, void *dev_id)
92{
93 struct clock_event_device *evt = dev_id;
94
95 sysctr_irq_acknowledge();
96
97 evt->event_handler(evt);
98
99 return IRQ_HANDLED;
100}
101
102static struct timer_of to_sysctr = {
103 .flags = TIMER_OF_IRQ | TIMER_OF_CLOCK | TIMER_OF_BASE,
104 .clkevt = {
105 .name = "i.MX system counter timer",
106 .features = CLOCK_EVT_FEAT_ONESHOT |
107 CLOCK_EVT_FEAT_DYNIRQ,
108 .set_state_oneshot = sysctr_set_state_oneshot,
109 .set_next_event = sysctr_set_next_event,
110 .set_state_shutdown = sysctr_set_state_shutdown,
111 .rating = 200,
112 },
113 .of_irq = {
114 .handler = sysctr_timer_interrupt,
115 .flags = IRQF_TIMER | IRQF_IRQPOLL,
116 },
117 .of_clk = {
118 .name = "per",
119 },
120};
121
122static void __init sysctr_clockevent_init(void)
123{
124 to_sysctr.clkevt.cpumask = cpumask_of(0);
125
126 clockevents_config_and_register(&to_sysctr.clkevt,
127 timer_of_rate(&to_sysctr),
128 0xff, 0x7fffffff);
129}
130
131static int __init sysctr_timer_init(struct device_node *np)
132{
133 int ret = 0;
134
135 ret = timer_of_init(np, &to_sysctr);
136 if (ret)
137 return ret;
138
139 /* system counter clock is divided by 3 internally */
140 to_sysctr.of_clk.rate /= SYS_CTR_CLK_DIV;
141
142 sys_ctr_base = timer_of_base(&to_sysctr);
143 cmpcr = readl(sys_ctr_base + CMPCR);
144 cmpcr &= ~SYS_CTR_EN;
145
146 sysctr_clockevent_init();
147
148 return 0;
149}
150TIMER_OF_DECLARE(sysctr_timer, "nxp,sysctr-timer", sysctr_timer_init);