1// SPDX-License-Identifier: GPL-2.0
2// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.
3
4#include <linux/init.h>
5#include <linux/interrupt.h>
6#include <linux/sched_clock.h>
7
8#include "timer-of.h"
9
10#define CLKSRC_OFFSET 0x40
11
12#define TIMER_STATUS 0x00
13#define TIMER_VALUE 0x04
14#define TIMER_CONTRL 0x10
15#define TIMER_CONFIG 0x20
16#define TIMER_DIV 0x24
17#define TIMER_INI 0x28
18
19#define GX6605S_STATUS_CLR BIT(0)
20#define GX6605S_CONTRL_RST BIT(0)
21#define GX6605S_CONTRL_START BIT(1)
22#define GX6605S_CONFIG_EN BIT(0)
23#define GX6605S_CONFIG_IRQ_EN BIT(1)
24
25static irqreturn_t gx6605s_timer_interrupt(int irq, void *dev)
26{
27 struct clock_event_device *ce = dev;
28 void __iomem *base = timer_of_base(to: to_timer_of(clkevt: ce));
29
30 writel_relaxed(GX6605S_STATUS_CLR, base + TIMER_STATUS);
31 writel_relaxed(0, base + TIMER_INI);
32
33 ce->event_handler(ce);
34
35 return IRQ_HANDLED;
36}
37
38static int gx6605s_timer_set_oneshot(struct clock_event_device *ce)
39{
40 void __iomem *base = timer_of_base(to: to_timer_of(clkevt: ce));
41
42 /* reset and stop counter */
43 writel_relaxed(GX6605S_CONTRL_RST, base + TIMER_CONTRL);
44
45 /* enable with irq and start */
46 writel_relaxed(GX6605S_CONFIG_EN | GX6605S_CONFIG_IRQ_EN,
47 base + TIMER_CONFIG);
48
49 return 0;
50}
51
52static int gx6605s_timer_set_next_event(unsigned long delta,
53 struct clock_event_device *ce)
54{
55 void __iomem *base = timer_of_base(to: to_timer_of(clkevt: ce));
56
57 /* use reset to pause timer */
58 writel_relaxed(GX6605S_CONTRL_RST, base + TIMER_CONTRL);
59
60 /* config next timeout value */
61 writel_relaxed(ULONG_MAX - delta, base + TIMER_INI);
62 writel_relaxed(GX6605S_CONTRL_START, base + TIMER_CONTRL);
63
64 return 0;
65}
66
67static int gx6605s_timer_shutdown(struct clock_event_device *ce)
68{
69 void __iomem *base = timer_of_base(to: to_timer_of(clkevt: ce));
70
71 writel_relaxed(0, base + TIMER_CONTRL);
72 writel_relaxed(0, base + TIMER_CONFIG);
73
74 return 0;
75}
76
77static struct timer_of to = {
78 .flags = TIMER_OF_IRQ | TIMER_OF_BASE | TIMER_OF_CLOCK,
79 .clkevt = {
80 .rating = 300,
81 .features = CLOCK_EVT_FEAT_DYNIRQ |
82 CLOCK_EVT_FEAT_ONESHOT,
83 .set_state_shutdown = gx6605s_timer_shutdown,
84 .set_state_oneshot = gx6605s_timer_set_oneshot,
85 .set_next_event = gx6605s_timer_set_next_event,
86 .cpumask = cpu_possible_mask,
87 },
88 .of_irq = {
89 .handler = gx6605s_timer_interrupt,
90 .flags = IRQF_TIMER | IRQF_IRQPOLL,
91 },
92};
93
94static u64 notrace gx6605s_sched_clock_read(void)
95{
96 void __iomem *base;
97
98 base = timer_of_base(to: &to) + CLKSRC_OFFSET;
99
100 return (u64)readl_relaxed(base + TIMER_VALUE);
101}
102
103static void gx6605s_clkevt_init(void __iomem *base)
104{
105 writel_relaxed(0, base + TIMER_DIV);
106 writel_relaxed(0, base + TIMER_CONFIG);
107
108 clockevents_config_and_register(dev: &to.clkevt, freq: timer_of_rate(to: &to), min_delta: 2,
109 ULONG_MAX);
110}
111
112static int gx6605s_clksrc_init(void __iomem *base)
113{
114 writel_relaxed(0, base + TIMER_DIV);
115 writel_relaxed(0, base + TIMER_INI);
116
117 writel_relaxed(GX6605S_CONTRL_RST, base + TIMER_CONTRL);
118
119 writel_relaxed(GX6605S_CONFIG_EN, base + TIMER_CONFIG);
120
121 writel_relaxed(GX6605S_CONTRL_START, base + TIMER_CONTRL);
122
123 sched_clock_register(read: gx6605s_sched_clock_read, bits: 32, rate: timer_of_rate(to: &to));
124
125 return clocksource_mmio_init(base + TIMER_VALUE, "gx6605s",
126 timer_of_rate(to: &to), 200, 32, clocksource_mmio_readl_up);
127}
128
129static int __init gx6605s_timer_init(struct device_node *np)
130{
131 int ret;
132
133 /*
134 * The timer driver is for nationalchip gx6605s SOC and there are two
135 * same timer in gx6605s. We use one for clkevt and another for clksrc.
136 *
137 * The timer is mmio map to access, so we need give mmio address in dts.
138 *
139 * It provides a 32bit countup timer and interrupt will be caused by
140 * count-overflow.
141 * So we need set-next-event by ULONG_MAX - delta in TIMER_INI reg.
142 *
143 * The counter at 0x0 offset is clock event.
144 * The counter at 0x40 offset is clock source.
145 * They are the same in hardware, just different used by driver.
146 */
147 ret = timer_of_init(np, to: &to);
148 if (ret)
149 return ret;
150
151 gx6605s_clkevt_init(base: timer_of_base(to: &to));
152
153 return gx6605s_clksrc_init(base: timer_of_base(to: &to) + CLKSRC_OFFSET);
154}
155TIMER_OF_DECLARE(csky_gx6605s_timer, "csky,gx6605s-timer", gx6605s_timer_init);
156

source code of linux/drivers/clocksource/timer-gx6605s.c