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 int __init _clps711x_clksrc_init(struct clk *clock, void __iomem *base)
35 {
36 	unsigned long rate;
37 
38 	if (!base)
39 		return -ENOMEM;
40 	if (IS_ERR(clock))
41 		return PTR_ERR(clock);
42 
43 	rate = clk_get_rate(clock);
44 
45 	tcd = base;
46 
47 	clocksource_mmio_init(tcd, "clps711x-clocksource", rate, 300, 16,
48 			      clocksource_mmio_readw_down);
49 
50 	sched_clock_register(clps711x_sched_clock_read, 16, rate);
51 
52 	return 0;
53 }
54 
55 static irqreturn_t clps711x_timer_interrupt(int irq, void *dev_id)
56 {
57 	struct clock_event_device *evt = dev_id;
58 
59 	evt->event_handler(evt);
60 
61 	return IRQ_HANDLED;
62 }
63 
64 static void clps711x_clockevent_set_mode(enum clock_event_mode mode,
65 					 struct clock_event_device *evt)
66 {
67 }
68 
69 static int __init _clps711x_clkevt_init(struct clk *clock, void __iomem *base,
70 					unsigned int irq)
71 {
72 	struct clock_event_device *clkevt;
73 	unsigned long rate;
74 
75 	if (!irq)
76 		return -EINVAL;
77 	if (!base)
78 		return -ENOMEM;
79 	if (IS_ERR(clock))
80 		return PTR_ERR(clock);
81 
82 	clkevt = kzalloc(sizeof(*clkevt), GFP_KERNEL);
83 	if (!clkevt)
84 		return -ENOMEM;
85 
86 	rate = clk_get_rate(clock);
87 
88 	/* Set Timer prescaler */
89 	writew(DIV_ROUND_CLOSEST(rate, HZ), base);
90 
91 	clkevt->name = "clps711x-clockevent";
92 	clkevt->rating = 300;
93 	clkevt->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_C3STOP;
94 	clkevt->set_mode = clps711x_clockevent_set_mode;
95 	clkevt->cpumask = cpumask_of(0);
96 	clockevents_config_and_register(clkevt, HZ, 0, 0);
97 
98 	return request_irq(irq, clps711x_timer_interrupt, IRQF_TIMER,
99 			   "clps711x-timer", clkevt);
100 }
101 
102 void __init clps711x_clksrc_init(void __iomem *tc1_base, void __iomem *tc2_base,
103 				 unsigned int irq)
104 {
105 	struct clk *tc1 = clk_get_sys("clps711x-timer.0", NULL);
106 	struct clk *tc2 = clk_get_sys("clps711x-timer.1", NULL);
107 
108 	BUG_ON(_clps711x_clksrc_init(tc1, tc1_base));
109 	BUG_ON(_clps711x_clkevt_init(tc2, tc2_base, irq));
110 }
111 
112 #ifdef CONFIG_CLKSRC_OF
113 static void __init clps711x_timer_init(struct device_node *np)
114 {
115 	unsigned int irq = irq_of_parse_and_map(np, 0);
116 	struct clk *clock = of_clk_get(np, 0);
117 	void __iomem *base = of_iomap(np, 0);
118 
119 	switch (of_alias_get_id(np, "timer")) {
120 	case CLPS711X_CLKSRC_CLOCKSOURCE:
121 		BUG_ON(_clps711x_clksrc_init(clock, base));
122 		break;
123 	case CLPS711X_CLKSRC_CLOCKEVENT:
124 		BUG_ON(_clps711x_clkevt_init(clock, base, irq));
125 		break;
126 	default:
127 		break;
128 	}
129 }
130 CLOCKSOURCE_OF_DECLARE(clps711x, "cirrus,clps711x-timer", clps711x_timer_init);
131 #endif
132