1 /*
2  *  Cirrus Logic CLPS711X clocksource driver
3  *
4  *  Copyright (C) 2014 Alexander Shiyan <shc_work@mail.ru>
5  *
6  * This program is free software; you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License as published by
8  * the Free Software Foundation; either version 2 of the License, or
9  * (at your option) any later version.
10  */
11 
12 #include <linux/clk.h>
13 #include <linux/clockchips.h>
14 #include <linux/clocksource.h>
15 #include <linux/interrupt.h>
16 #include <linux/io.h>
17 #include <linux/of_address.h>
18 #include <linux/of_irq.h>
19 #include <linux/sched_clock.h>
20 #include <linux/slab.h>
21 
22 enum {
23 	CLPS711X_CLKSRC_CLOCKSOURCE,
24 	CLPS711X_CLKSRC_CLOCKEVENT,
25 };
26 
27 static void __iomem *tcd;
28 
29 static u64 notrace clps711x_sched_clock_read(void)
30 {
31 	return ~readw(tcd);
32 }
33 
34 static void __init clps711x_clksrc_init(struct clk *clock, void __iomem *base)
35 {
36 	unsigned long rate = clk_get_rate(clock);
37 
38 	tcd = base;
39 
40 	clocksource_mmio_init(tcd, "clps711x-clocksource", rate, 300, 16,
41 			      clocksource_mmio_readw_down);
42 
43 	sched_clock_register(clps711x_sched_clock_read, 16, rate);
44 }
45 
46 static irqreturn_t clps711x_timer_interrupt(int irq, void *dev_id)
47 {
48 	struct clock_event_device *evt = dev_id;
49 
50 	evt->event_handler(evt);
51 
52 	return IRQ_HANDLED;
53 }
54 
55 static int __init _clps711x_clkevt_init(struct clk *clock, void __iomem *base,
56 					unsigned int irq)
57 {
58 	struct clock_event_device *clkevt;
59 	unsigned long rate;
60 
61 	clkevt = kzalloc(sizeof(*clkevt), GFP_KERNEL);
62 	if (!clkevt)
63 		return -ENOMEM;
64 
65 	rate = clk_get_rate(clock);
66 
67 	/* Set Timer prescaler */
68 	writew(DIV_ROUND_CLOSEST(rate, HZ), base);
69 
70 	clkevt->name = "clps711x-clockevent";
71 	clkevt->rating = 300;
72 	clkevt->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_C3STOP;
73 	clkevt->cpumask = cpumask_of(0);
74 	clockevents_config_and_register(clkevt, HZ, 0, 0);
75 
76 	return request_irq(irq, clps711x_timer_interrupt, IRQF_TIMER,
77 			   "clps711x-timer", clkevt);
78 }
79 
80 static int __init clps711x_timer_init(struct device_node *np)
81 {
82 	unsigned int irq = irq_of_parse_and_map(np, 0);
83 	struct clk *clock = of_clk_get(np, 0);
84 	void __iomem *base = of_iomap(np, 0);
85 
86 	if (!base)
87 		return -ENOMEM;
88 	if (!irq)
89 		return -EINVAL;
90 	if (IS_ERR(clock))
91 		return PTR_ERR(clock);
92 
93 	switch (of_alias_get_id(np, "timer")) {
94 	case CLPS711X_CLKSRC_CLOCKSOURCE:
95 		clps711x_clksrc_init(clock, base);
96 		break;
97 	case CLPS711X_CLKSRC_CLOCKEVENT:
98 		return _clps711x_clkevt_init(clock, base, irq);
99 	default:
100 		return -EINVAL;
101 	}
102 
103 	return 0;
104 }
105 TIMER_OF_DECLARE(clps711x, "cirrus,ep7209-timer", clps711x_timer_init);
106