1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Cirrus Logic CLPS711X clocksource driver
4 *
5 * Copyright (C) 2014 Alexander Shiyan <shc_work@mail.ru>
6 */
7
8 #include <linux/clk.h>
9 #include <linux/clockchips.h>
10 #include <linux/clocksource.h>
11 #include <linux/interrupt.h>
12 #include <linux/io.h>
13 #include <linux/of_address.h>
14 #include <linux/of_irq.h>
15 #include <linux/sched_clock.h>
16 #include <linux/slab.h>
17
18 enum {
19 CLPS711X_CLKSRC_CLOCKSOURCE,
20 CLPS711X_CLKSRC_CLOCKEVENT,
21 };
22
23 static void __iomem *tcd;
24
clps711x_sched_clock_read(void)25 static u64 notrace clps711x_sched_clock_read(void)
26 {
27 return ~readw(tcd);
28 }
29
clps711x_clksrc_init(struct clk * clock,void __iomem * base)30 static void __init clps711x_clksrc_init(struct clk *clock, void __iomem *base)
31 {
32 unsigned long rate = clk_get_rate(clock);
33
34 tcd = base;
35
36 clocksource_mmio_init(tcd, "clps711x-clocksource", rate, 300, 16,
37 clocksource_mmio_readw_down);
38
39 sched_clock_register(clps711x_sched_clock_read, 16, rate);
40 }
41
clps711x_timer_interrupt(int irq,void * dev_id)42 static irqreturn_t clps711x_timer_interrupt(int irq, void *dev_id)
43 {
44 struct clock_event_device *evt = dev_id;
45
46 evt->event_handler(evt);
47
48 return IRQ_HANDLED;
49 }
50
_clps711x_clkevt_init(struct clk * clock,void __iomem * base,unsigned int irq)51 static int __init _clps711x_clkevt_init(struct clk *clock, void __iomem *base,
52 unsigned int irq)
53 {
54 struct clock_event_device *clkevt;
55 unsigned long rate;
56
57 clkevt = kzalloc(sizeof(*clkevt), GFP_KERNEL);
58 if (!clkevt)
59 return -ENOMEM;
60
61 rate = clk_get_rate(clock);
62
63 /* Set Timer prescaler */
64 writew(DIV_ROUND_CLOSEST(rate, HZ), base);
65
66 clkevt->name = "clps711x-clockevent";
67 clkevt->rating = 300;
68 clkevt->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_C3STOP;
69 clkevt->cpumask = cpumask_of(0);
70 clockevents_config_and_register(clkevt, HZ, 0, 0);
71
72 return request_irq(irq, clps711x_timer_interrupt, IRQF_TIMER,
73 "clps711x-timer", clkevt);
74 }
75
clps711x_timer_init(struct device_node * np)76 static int __init clps711x_timer_init(struct device_node *np)
77 {
78 unsigned int irq = irq_of_parse_and_map(np, 0);
79 struct clk *clock = of_clk_get(np, 0);
80 void __iomem *base = of_iomap(np, 0);
81
82 if (!base)
83 return -ENOMEM;
84 if (!irq)
85 return -EINVAL;
86 if (IS_ERR(clock))
87 return PTR_ERR(clock);
88
89 switch (of_alias_get_id(np, "timer")) {
90 case CLPS711X_CLKSRC_CLOCKSOURCE:
91 clps711x_clksrc_init(clock, base);
92 break;
93 case CLPS711X_CLKSRC_CLOCKEVENT:
94 return _clps711x_clkevt_init(clock, base, irq);
95 default:
96 return -EINVAL;
97 }
98
99 return 0;
100 }
101 TIMER_OF_DECLARE(clps711x, "cirrus,ep7209-timer", clps711x_timer_init);
102