xref: /openbmc/linux/arch/mips/ralink/cevt-rt3352.c (revision ac8fd122)
1 /*
2  * This file is subject to the terms and conditions of the GNU General Public
3  * License.  See the file "COPYING" in the main directory of this archive
4  * for more details.
5  *
6  * Copyright (C) 2013 by John Crispin <john@phrozen.org>
7  */
8 
9 #include <linux/clockchips.h>
10 #include <linux/clocksource.h>
11 #include <linux/interrupt.h>
12 #include <linux/reset.h>
13 #include <linux/init.h>
14 #include <linux/time.h>
15 #include <linux/of.h>
16 #include <linux/of_irq.h>
17 #include <linux/of_address.h>
18 
19 #include <asm/mach-ralink/ralink_regs.h>
20 
21 #define SYSTICK_FREQ		(50 * 1000)
22 
23 #define SYSTICK_CONFIG		0x00
24 #define SYSTICK_COMPARE		0x04
25 #define SYSTICK_COUNT		0x08
26 
27 /* route systick irq to mips irq 7 instead of the r4k-timer */
28 #define CFG_EXT_STK_EN		0x2
29 /* enable the counter */
30 #define CFG_CNT_EN		0x1
31 
32 struct systick_device {
33 	void __iomem *membase;
34 	struct clock_event_device dev;
35 	int irq_requested;
36 	int freq_scale;
37 };
38 
39 static int systick_set_oneshot(struct clock_event_device *evt);
40 static int systick_shutdown(struct clock_event_device *evt);
41 
systick_next_event(unsigned long delta,struct clock_event_device * evt)42 static int systick_next_event(unsigned long delta,
43 				struct clock_event_device *evt)
44 {
45 	struct systick_device *sdev;
46 	u32 count;
47 
48 	sdev = container_of(evt, struct systick_device, dev);
49 	count = ioread32(sdev->membase + SYSTICK_COUNT);
50 	count = (count + delta) % SYSTICK_FREQ;
51 	iowrite32(count, sdev->membase + SYSTICK_COMPARE);
52 
53 	return 0;
54 }
55 
systick_event_handler(struct clock_event_device * dev)56 static void systick_event_handler(struct clock_event_device *dev)
57 {
58 	/* noting to do here */
59 }
60 
systick_interrupt(int irq,void * dev_id)61 static irqreturn_t systick_interrupt(int irq, void *dev_id)
62 {
63 	struct clock_event_device *dev = (struct clock_event_device *) dev_id;
64 
65 	dev->event_handler(dev);
66 
67 	return IRQ_HANDLED;
68 }
69 
70 static struct systick_device systick = {
71 	.dev = {
72 		/*
73 		 * cevt-r4k uses 300, make sure systick
74 		 * gets used if available
75 		 */
76 		.rating			= 310,
77 		.features		= CLOCK_EVT_FEAT_ONESHOT,
78 		.set_next_event		= systick_next_event,
79 		.set_state_shutdown	= systick_shutdown,
80 		.set_state_oneshot	= systick_set_oneshot,
81 		.event_handler		= systick_event_handler,
82 	},
83 };
84 
systick_shutdown(struct clock_event_device * evt)85 static int systick_shutdown(struct clock_event_device *evt)
86 {
87 	struct systick_device *sdev;
88 
89 	sdev = container_of(evt, struct systick_device, dev);
90 
91 	if (sdev->irq_requested)
92 		free_irq(systick.dev.irq, &systick.dev);
93 	sdev->irq_requested = 0;
94 	iowrite32(0, systick.membase + SYSTICK_CONFIG);
95 
96 	return 0;
97 }
98 
systick_set_oneshot(struct clock_event_device * evt)99 static int systick_set_oneshot(struct clock_event_device *evt)
100 {
101 	const char *name = systick.dev.name;
102 	struct systick_device *sdev;
103 	int irq = systick.dev.irq;
104 
105 	sdev = container_of(evt, struct systick_device, dev);
106 
107 	if (!sdev->irq_requested) {
108 		if (request_irq(irq, systick_interrupt,
109 				IRQF_PERCPU | IRQF_TIMER, name, &systick.dev))
110 			pr_err("Failed to request irq %d (%s)\n", irq, name);
111 	}
112 	sdev->irq_requested = 1;
113 	iowrite32(CFG_EXT_STK_EN | CFG_CNT_EN,
114 		  systick.membase + SYSTICK_CONFIG);
115 
116 	return 0;
117 }
118 
ralink_systick_init(struct device_node * np)119 static int __init ralink_systick_init(struct device_node *np)
120 {
121 	int ret;
122 
123 	systick.membase = of_iomap(np, 0);
124 	if (!systick.membase)
125 		return -ENXIO;
126 
127 	systick.dev.name = np->name;
128 	clockevents_calc_mult_shift(&systick.dev, SYSTICK_FREQ, 60);
129 	systick.dev.max_delta_ns = clockevent_delta2ns(0x7fff, &systick.dev);
130 	systick.dev.max_delta_ticks = 0x7fff;
131 	systick.dev.min_delta_ns = clockevent_delta2ns(0x3, &systick.dev);
132 	systick.dev.min_delta_ticks = 0x3;
133 	systick.dev.irq = irq_of_parse_and_map(np, 0);
134 	if (!systick.dev.irq) {
135 		pr_err("%pOFn: request_irq failed", np);
136 		return -EINVAL;
137 	}
138 
139 	ret = clocksource_mmio_init(systick.membase + SYSTICK_COUNT, np->name,
140 				    SYSTICK_FREQ, 301, 16,
141 				    clocksource_mmio_readl_up);
142 	if (ret)
143 		return ret;
144 
145 	clockevents_register_device(&systick.dev);
146 
147 	pr_info("%pOFn: running - mult: %d, shift: %d\n",
148 			np, systick.dev.mult, systick.dev.shift);
149 
150 	return 0;
151 }
152 
153 TIMER_OF_DECLARE(systick, "ralink,cevt-systick", ralink_systick_init);
154