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80ecbd24 | 1 | /* |
62ee73d2 PG |
2 | * Ralink RT2880 timer |
3 | * Author: John Crispin | |
4 | * | |
80ecbd24 JC |
5 | * This program is free software; you can redistribute it and/or modify it |
6 | * under the terms of the GNU General Public License version 2 as published | |
7 | * by the Free Software Foundation. | |
8 | * | |
97b92108 | 9 | * Copyright (C) 2013 John Crispin <john@phrozen.org> |
80ecbd24 JC |
10 | */ |
11 | ||
80ecbd24 JC |
12 | #include <linux/platform_device.h> |
13 | #include <linux/interrupt.h> | |
14 | #include <linux/timer.h> | |
15 | #include <linux/of_gpio.h> | |
16 | #include <linux/clk.h> | |
17 | ||
18 | #include <asm/mach-ralink/ralink_regs.h> | |
19 | ||
20 | #define TIMER_REG_TMRSTAT 0x00 | |
21 | #define TIMER_REG_TMR0LOAD 0x10 | |
22 | #define TIMER_REG_TMR0CTL 0x18 | |
23 | ||
24 | #define TMRSTAT_TMR0INT BIT(0) | |
25 | ||
26 | #define TMR0CTL_ENABLE BIT(7) | |
27 | #define TMR0CTL_MODE_PERIODIC BIT(4) | |
28 | #define TMR0CTL_PRESCALER 1 | |
29 | #define TMR0CTL_PRESCALE_VAL (0xf - TMR0CTL_PRESCALER) | |
30 | #define TMR0CTL_PRESCALE_DIV (65536 / BIT(TMR0CTL_PRESCALER)) | |
31 | ||
32 | struct rt_timer { | |
33 | struct device *dev; | |
34 | void __iomem *membase; | |
35 | int irq; | |
36 | unsigned long timer_freq; | |
37 | unsigned long timer_div; | |
38 | }; | |
39 | ||
40 | static inline void rt_timer_w32(struct rt_timer *rt, u8 reg, u32 val) | |
41 | { | |
42 | __raw_writel(val, rt->membase + reg); | |
43 | } | |
44 | ||
45 | static inline u32 rt_timer_r32(struct rt_timer *rt, u8 reg) | |
46 | { | |
47 | return __raw_readl(rt->membase + reg); | |
48 | } | |
49 | ||
50 | static irqreturn_t rt_timer_irq(int irq, void *_rt) | |
51 | { | |
52 | struct rt_timer *rt = (struct rt_timer *) _rt; | |
53 | ||
54 | rt_timer_w32(rt, TIMER_REG_TMR0LOAD, rt->timer_freq / rt->timer_div); | |
55 | rt_timer_w32(rt, TIMER_REG_TMRSTAT, TMRSTAT_TMR0INT); | |
56 | ||
57 | return IRQ_HANDLED; | |
58 | } | |
59 | ||
60 | ||
61 | static int rt_timer_request(struct rt_timer *rt) | |
62 | { | |
31d6f57d | 63 | int err = request_irq(rt->irq, rt_timer_irq, 0, |
80ecbd24 JC |
64 | dev_name(rt->dev), rt); |
65 | if (err) { | |
66 | dev_err(rt->dev, "failed to request irq\n"); | |
67 | } else { | |
68 | u32 t = TMR0CTL_MODE_PERIODIC | TMR0CTL_PRESCALE_VAL; | |
69 | rt_timer_w32(rt, TIMER_REG_TMR0CTL, t); | |
70 | } | |
71 | return err; | |
72 | } | |
73 | ||
74 | static void rt_timer_free(struct rt_timer *rt) | |
75 | { | |
76 | free_irq(rt->irq, rt); | |
77 | } | |
78 | ||
79 | static int rt_timer_config(struct rt_timer *rt, unsigned long divisor) | |
80 | { | |
81 | if (rt->timer_freq < divisor) | |
82 | rt->timer_div = rt->timer_freq; | |
83 | else | |
84 | rt->timer_div = divisor; | |
85 | ||
86 | rt_timer_w32(rt, TIMER_REG_TMR0LOAD, rt->timer_freq / rt->timer_div); | |
87 | ||
88 | return 0; | |
89 | } | |
90 | ||
91 | static int rt_timer_enable(struct rt_timer *rt) | |
92 | { | |
93 | u32 t; | |
94 | ||
95 | rt_timer_w32(rt, TIMER_REG_TMR0LOAD, rt->timer_freq / rt->timer_div); | |
96 | ||
97 | t = rt_timer_r32(rt, TIMER_REG_TMR0CTL); | |
98 | t |= TMR0CTL_ENABLE; | |
99 | rt_timer_w32(rt, TIMER_REG_TMR0CTL, t); | |
100 | ||
101 | return 0; | |
102 | } | |
103 | ||
104 | static void rt_timer_disable(struct rt_timer *rt) | |
105 | { | |
106 | u32 t; | |
107 | ||
108 | t = rt_timer_r32(rt, TIMER_REG_TMR0CTL); | |
109 | t &= ~TMR0CTL_ENABLE; | |
110 | rt_timer_w32(rt, TIMER_REG_TMR0CTL, t); | |
111 | } | |
112 | ||
113 | static int rt_timer_probe(struct platform_device *pdev) | |
114 | { | |
115 | struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0); | |
116 | struct rt_timer *rt; | |
117 | struct clk *clk; | |
118 | ||
119 | rt = devm_kzalloc(&pdev->dev, sizeof(*rt), GFP_KERNEL); | |
120 | if (!rt) { | |
121 | dev_err(&pdev->dev, "failed to allocate memory\n"); | |
122 | return -ENOMEM; | |
123 | } | |
124 | ||
125 | rt->irq = platform_get_irq(pdev, 0); | |
126 | if (!rt->irq) { | |
127 | dev_err(&pdev->dev, "failed to load irq\n"); | |
128 | return -ENOENT; | |
129 | } | |
130 | ||
cd5d5810 | 131 | rt->membase = devm_ioremap_resource(&pdev->dev, res); |
80ecbd24 JC |
132 | if (IS_ERR(rt->membase)) |
133 | return PTR_ERR(rt->membase); | |
134 | ||
135 | clk = devm_clk_get(&pdev->dev, NULL); | |
136 | if (IS_ERR(clk)) { | |
137 | dev_err(&pdev->dev, "failed get clock rate\n"); | |
138 | return PTR_ERR(clk); | |
139 | } | |
140 | ||
141 | rt->timer_freq = clk_get_rate(clk) / TMR0CTL_PRESCALE_DIV; | |
142 | if (!rt->timer_freq) | |
143 | return -EINVAL; | |
144 | ||
145 | rt->dev = &pdev->dev; | |
146 | platform_set_drvdata(pdev, rt); | |
147 | ||
148 | rt_timer_request(rt); | |
149 | rt_timer_config(rt, 2); | |
150 | rt_timer_enable(rt); | |
151 | ||
77d84ff8 | 152 | dev_info(&pdev->dev, "maximum frequency is %luHz\n", rt->timer_freq); |
80ecbd24 JC |
153 | |
154 | return 0; | |
155 | } | |
156 | ||
80ecbd24 JC |
157 | static const struct of_device_id rt_timer_match[] = { |
158 | { .compatible = "ralink,rt2880-timer" }, | |
159 | {}, | |
160 | }; | |
80ecbd24 JC |
161 | |
162 | static struct platform_driver rt_timer_driver = { | |
163 | .probe = rt_timer_probe, | |
80ecbd24 | 164 | .driver = { |
62ee73d2 PG |
165 | .name = "rt-timer", |
166 | .of_match_table = rt_timer_match, | |
167 | .suppress_bind_attrs = true, | |
80ecbd24 JC |
168 | }, |
169 | }; | |
62ee73d2 | 170 | builtin_platform_driver(rt_timer_driver); |