Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
1/*
2 * Ralink RT2880 timer
3 * Author: John Crispin
4 *
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 *
9 * Copyright (C) 2013 John Crispin <john@phrozen.org>
10*/
11
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
32struct 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
40static inline void rt_timer_w32(struct rt_timer *rt, u8 reg, u32 val)
41{
42 __raw_writel(val, rt->membase + reg);
43}
44
45static inline u32 rt_timer_r32(struct rt_timer *rt, u8 reg)
46{
47 return __raw_readl(rt->membase + reg);
48}
49
50static 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
61static int rt_timer_request(struct rt_timer *rt)
62{
63 int err = request_irq(rt->irq, rt_timer_irq, 0,
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
74static void rt_timer_free(struct rt_timer *rt)
75{
76 free_irq(rt->irq, rt);
77}
78
79static 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
91static 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
104static 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
113static 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
131 rt->membase = devm_ioremap_resource(&pdev->dev, res);
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
152 dev_info(&pdev->dev, "maximum frequency is %luHz\n", rt->timer_freq);
153
154 return 0;
155}
156
157static const struct of_device_id rt_timer_match[] = {
158 { .compatible = "ralink,rt2880-timer" },
159 {},
160};
161
162static struct platform_driver rt_timer_driver = {
163 .probe = rt_timer_probe,
164 .driver = {
165 .name = "rt-timer",
166 .of_match_table = rt_timer_match,
167 .suppress_bind_attrs = true,
168 },
169};
170builtin_platform_driver(rt_timer_driver);