GNU Linux-libre 4.19.286-gnu1
[releases.git] / arch / mips / ralink / timer.c
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
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 {
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
74 static int rt_timer_config(struct rt_timer *rt, unsigned long divisor)
75 {
76         if (rt->timer_freq < divisor)
77                 rt->timer_div = rt->timer_freq;
78         else
79                 rt->timer_div = divisor;
80
81         rt_timer_w32(rt, TIMER_REG_TMR0LOAD, rt->timer_freq / rt->timer_div);
82
83         return 0;
84 }
85
86 static int rt_timer_enable(struct rt_timer *rt)
87 {
88         u32 t;
89
90         rt_timer_w32(rt, TIMER_REG_TMR0LOAD, rt->timer_freq / rt->timer_div);
91
92         t = rt_timer_r32(rt, TIMER_REG_TMR0CTL);
93         t |= TMR0CTL_ENABLE;
94         rt_timer_w32(rt, TIMER_REG_TMR0CTL, t);
95
96         return 0;
97 }
98
99 static int rt_timer_probe(struct platform_device *pdev)
100 {
101         struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
102         struct rt_timer *rt;
103         struct clk *clk;
104
105         rt = devm_kzalloc(&pdev->dev, sizeof(*rt), GFP_KERNEL);
106         if (!rt) {
107                 dev_err(&pdev->dev, "failed to allocate memory\n");
108                 return -ENOMEM;
109         }
110
111         rt->irq = platform_get_irq(pdev, 0);
112         if (rt->irq < 0) {
113                 dev_err(&pdev->dev, "failed to load irq\n");
114                 return rt->irq;
115         }
116
117         rt->membase = devm_ioremap_resource(&pdev->dev, res);
118         if (IS_ERR(rt->membase))
119                 return PTR_ERR(rt->membase);
120
121         clk = devm_clk_get(&pdev->dev, NULL);
122         if (IS_ERR(clk)) {
123                 dev_err(&pdev->dev, "failed get clock rate\n");
124                 return PTR_ERR(clk);
125         }
126
127         rt->timer_freq = clk_get_rate(clk) / TMR0CTL_PRESCALE_DIV;
128         if (!rt->timer_freq)
129                 return -EINVAL;
130
131         rt->dev = &pdev->dev;
132         platform_set_drvdata(pdev, rt);
133
134         rt_timer_request(rt);
135         rt_timer_config(rt, 2);
136         rt_timer_enable(rt);
137
138         dev_info(&pdev->dev, "maximum frequency is %luHz\n", rt->timer_freq);
139
140         return 0;
141 }
142
143 static const struct of_device_id rt_timer_match[] = {
144         { .compatible = "ralink,rt2880-timer" },
145         {},
146 };
147
148 static struct platform_driver rt_timer_driver = {
149         .probe = rt_timer_probe,
150         .driver = {
151                 .name                   = "rt-timer",
152                 .of_match_table         = rt_timer_match,
153                 .suppress_bind_attrs    = true,
154         },
155 };
156 builtin_platform_driver(rt_timer_driver);