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 
25 static u64 notrace clps711x_sched_clock_read(void)
26 {
27 	return ~readw(tcd);
28 }
29 
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 
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 
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 
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