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1f2acc5a JC |
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 <blogic@openwrt.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 void systick_set_clock_mode(enum clock_event_mode mode, | |
40 | 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 + delta, 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_mode = systick_set_clock_mode, | |
80 | .event_handler = systick_event_handler, | |
81 | }, | |
82 | }; | |
83 | ||
84 | static struct irqaction systick_irqaction = { | |
85 | .handler = systick_interrupt, | |
86 | .flags = IRQF_PERCPU | IRQF_TIMER, | |
87 | .dev_id = &systick.dev, | |
88 | }; | |
89 | ||
90 | static void systick_set_clock_mode(enum clock_event_mode mode, | |
91 | struct clock_event_device *evt) | |
92 | { | |
93 | struct systick_device *sdev; | |
94 | ||
95 | sdev = container_of(evt, struct systick_device, dev); | |
96 | ||
97 | switch (mode) { | |
98 | case CLOCK_EVT_MODE_ONESHOT: | |
99 | if (!sdev->irq_requested) | |
100 | setup_irq(systick.dev.irq, &systick_irqaction); | |
101 | sdev->irq_requested = 1; | |
102 | iowrite32(CFG_EXT_STK_EN | CFG_CNT_EN, | |
103 | systick.membase + SYSTICK_CONFIG); | |
104 | break; | |
105 | ||
106 | case CLOCK_EVT_MODE_SHUTDOWN: | |
107 | if (sdev->irq_requested) | |
108 | free_irq(systick.dev.irq, &systick_irqaction); | |
109 | sdev->irq_requested = 0; | |
110 | iowrite32(0, systick.membase + SYSTICK_CONFIG); | |
111 | break; | |
112 | ||
113 | default: | |
114 | pr_err("%s: Unhandeled mips clock_mode\n", systick.dev.name); | |
115 | break; | |
116 | } | |
117 | } | |
118 | ||
119 | static void __init ralink_systick_init(struct device_node *np) | |
120 | { | |
121 | systick.membase = of_iomap(np, 0); | |
122 | if (!systick.membase) | |
123 | return; | |
124 | ||
125 | systick_irqaction.name = np->name; | |
126 | systick.dev.name = np->name; | |
127 | clockevents_calc_mult_shift(&systick.dev, SYSTICK_FREQ, 60); | |
128 | systick.dev.max_delta_ns = clockevent_delta2ns(0x7fff, &systick.dev); | |
129 | systick.dev.min_delta_ns = clockevent_delta2ns(0x3, &systick.dev); | |
130 | systick.dev.irq = irq_of_parse_and_map(np, 0); | |
131 | if (!systick.dev.irq) { | |
132 | pr_err("%s: request_irq failed", np->name); | |
133 | return; | |
134 | } | |
135 | ||
136 | clocksource_mmio_init(systick.membase + SYSTICK_COUNT, np->name, | |
137 | SYSTICK_FREQ, 301, 16, clocksource_mmio_readl_up); | |
138 | ||
139 | clockevents_register_device(&systick.dev); | |
140 | ||
141 | pr_info("%s: runing - mult: %d, shift: %d\n", | |
142 | np->name, systick.dev.mult, systick.dev.shift); | |
143 | } | |
144 | ||
145 | CLOCKSOURCE_OF_DECLARE(systick, "ralink,cevt-systick", ralink_systick_init); |