1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
|
// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright 2012-2013 Freescale Semiconductor, Inc.
*/
#include <linux/interrupt.h>
#include <linux/clockchips.h>
#include <linux/clk.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/sched_clock.h>
/*
* Each pit takes 0x10 Bytes register space
*/
#define PITMCR 0x00
#define PIT0_OFFSET 0x100
#define PITn_OFFSET(n) (PIT0_OFFSET + 0x10 * (n))
#define PITLDVAL 0x00
#define PITCVAL 0x04
#define PITTCTRL 0x08
#define PITTFLG 0x0c
#define PITMCR_MDIS (0x1 << 1)
#define PITTCTRL_TEN (0x1 << 0)
#define PITTCTRL_TIE (0x1 << 1)
#define PITCTRL_CHN (0x1 << 2)
#define PITTFLG_TIF 0x1
static void __iomem *clksrc_base;
static void __iomem *clkevt_base;
static unsigned long cycle_per_jiffy;
static inline void pit_timer_enable(void)
{
__raw_writel(PITTCTRL_TEN | PITTCTRL_TIE, clkevt_base + PITTCTRL);
}
static inline void pit_timer_disable(void)
{
__raw_writel(0, clkevt_base + PITTCTRL);
}
static inline void pit_irq_acknowledge(void)
{
__raw_writel(PITTFLG_TIF, clkevt_base + PITTFLG);
}
static u64 notrace pit_read_sched_clock(void)
{
return ~__raw_readl(clksrc_base + PITCVAL);
}
static int __init pit_clocksource_init(unsigned long rate)
{
/* set the max load value and start the clock source counter */
__raw_writel(0, clksrc_base + PITTCTRL);
__raw_writel(~0UL, clksrc_base + PITLDVAL);
__raw_writel(PITTCTRL_TEN, clksrc_base + PITTCTRL);
sched_clock_register(pit_read_sched_clock, 32, rate);
return clocksource_mmio_init(clksrc_base + PITCVAL, "vf-pit", rate,
300, 32, clocksource_mmio_readl_down);
}
static int pit_set_next_event(unsigned long delta,
struct clock_event_device *unused)
{
/*
* set a new value to PITLDVAL register will not restart the timer,
* to abort the current cycle and start a timer period with the new
* value, the timer must be disabled and enabled again.
* and the PITLAVAL should be set to delta minus one according to pit
* hardware requirement.
*/
pit_timer_disable();
__raw_writel(delta - 1, clkevt_base + PITLDVAL);
pit_timer_enable();
return 0;
}
static int pit_shutdown(struct clock_event_device *evt)
{
pit_timer_disable();
return 0;
}
static int pit_set_periodic(struct clock_event_device *evt)
{
pit_set_next_event(cycle_per_jiffy, evt);
return 0;
}
static irqreturn_t pit_timer_interrupt(int irq, void *dev_id)
{
struct clock_event_device *evt = dev_id;
pit_irq_acknowledge();
/*
* pit hardware doesn't support oneshot, it will generate an interrupt
* and reload the counter value from PITLDVAL when PITCVAL reach zero,
* and start the counter again. So software need to disable the timer
* to stop the counter loop in ONESHOT mode.
*/
if (likely(clockevent_state_oneshot(evt)))
pit_timer_disable();
evt->event_handler(evt);
return IRQ_HANDLED;
}
static struct clock_event_device clockevent_pit = {
.name = "VF pit timer",
.features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
.set_state_shutdown = pit_shutdown,
.set_state_periodic = pit_set_periodic,
.set_next_event = pit_set_next_event,
.rating = 300,
};
static struct irqaction pit_timer_irq = {
.name = "VF pit timer",
.flags = IRQF_TIMER | IRQF_IRQPOLL,
.handler = pit_timer_interrupt,
.dev_id = &clockevent_pit,
};
static int __init pit_clockevent_init(unsigned long rate, int irq)
{
__raw_writel(0, clkevt_base + PITTCTRL);
__raw_writel(PITTFLG_TIF, clkevt_base + PITTFLG);
BUG_ON(setup_irq(irq, &pit_timer_irq));
clockevent_pit.cpumask = cpumask_of(0);
clockevent_pit.irq = irq;
/*
* The value for the LDVAL register trigger is calculated as:
* LDVAL trigger = (period / clock period) - 1
* The pit is a 32-bit down count timer, when the conter value
* reaches 0, it will generate an interrupt, thus the minimal
* LDVAL trigger value is 1. And then the min_delta is
* minimal LDVAL trigger value + 1, and the max_delta is full 32-bit.
*/
clockevents_config_and_register(&clockevent_pit, rate, 2, 0xffffffff);
return 0;
}
static int __init pit_timer_init(struct device_node *np)
{
struct clk *pit_clk;
void __iomem *timer_base;
unsigned long clk_rate;
int irq, ret;
timer_base = of_iomap(np, 0);
if (!timer_base) {
pr_err("Failed to iomap\n");
return -ENXIO;
}
/*
* PIT0 and PIT1 can be chained to build a 64-bit timer,
* so choose PIT2 as clocksource, PIT3 as clockevent device,
* and leave PIT0 and PIT1 unused for anyone else who needs them.
*/
clksrc_base = timer_base + PITn_OFFSET(2);
clkevt_base = timer_base + PITn_OFFSET(3);
irq = irq_of_parse_and_map(np, 0);
if (irq <= 0)
return -EINVAL;
pit_clk = of_clk_get(np, 0);
if (IS_ERR(pit_clk))
return PTR_ERR(pit_clk);
ret = clk_prepare_enable(pit_clk);
if (ret)
return ret;
clk_rate = clk_get_rate(pit_clk);
cycle_per_jiffy = clk_rate / (HZ);
/* enable the pit module */
__raw_writel(~PITMCR_MDIS, timer_base + PITMCR);
ret = pit_clocksource_init(clk_rate);
if (ret)
return ret;
return pit_clockevent_init(clk_rate, irq);
}
TIMER_OF_DECLARE(vf610, "fsl,vf610-pit", pit_timer_init);
|
