GNU Linux-libre 4.19.286-gnu1
[releases.git] / arch / mips / ralink / cevt-rt3352.c
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
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
56 static void systick_event_handler(struct clock_event_device *dev)
57 {
58         /* noting to do here */
59 }
60
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
85 static struct irqaction systick_irqaction = {
86         .handler = systick_interrupt,
87         .flags = IRQF_PERCPU | IRQF_TIMER,
88         .dev_id = &systick.dev,
89 };
90
91 static int systick_shutdown(struct clock_event_device *evt)
92 {
93         struct systick_device *sdev;
94
95         sdev = container_of(evt, struct systick_device, dev);
96
97         if (sdev->irq_requested)
98                 free_irq(systick.dev.irq, &systick_irqaction);
99         sdev->irq_requested = 0;
100         iowrite32(0, systick.membase + SYSTICK_CONFIG);
101
102         return 0;
103 }
104
105 static int systick_set_oneshot(struct clock_event_device *evt)
106 {
107         struct systick_device *sdev;
108
109         sdev = container_of(evt, struct systick_device, dev);
110
111         if (!sdev->irq_requested)
112                 setup_irq(systick.dev.irq, &systick_irqaction);
113         sdev->irq_requested = 1;
114         iowrite32(CFG_EXT_STK_EN | CFG_CNT_EN,
115                   systick.membase + SYSTICK_CONFIG);
116
117         return 0;
118 }
119
120 static int __init ralink_systick_init(struct device_node *np)
121 {
122         int ret;
123
124         systick.membase = of_iomap(np, 0);
125         if (!systick.membase)
126                 return -ENXIO;
127
128         systick_irqaction.name = np->name;
129         systick.dev.name = np->name;
130         clockevents_calc_mult_shift(&systick.dev, SYSTICK_FREQ, 60);
131         systick.dev.max_delta_ns = clockevent_delta2ns(0x7fff, &systick.dev);
132         systick.dev.max_delta_ticks = 0x7fff;
133         systick.dev.min_delta_ns = clockevent_delta2ns(0x3, &systick.dev);
134         systick.dev.min_delta_ticks = 0x3;
135         systick.dev.irq = irq_of_parse_and_map(np, 0);
136         if (!systick.dev.irq) {
137                 pr_err("%s: request_irq failed", np->name);
138                 return -EINVAL;
139         }
140
141         ret = clocksource_mmio_init(systick.membase + SYSTICK_COUNT, np->name,
142                                     SYSTICK_FREQ, 301, 16,
143                                     clocksource_mmio_readl_up);
144         if (ret)
145                 return ret;
146
147         clockevents_register_device(&systick.dev);
148
149         pr_info("%s: running - mult: %d, shift: %d\n",
150                         np->name, systick.dev.mult, systick.dev.shift);
151
152         return 0;
153 }
154
155 TIMER_OF_DECLARE(systick, "ralink,cevt-systick", ralink_systick_init);