xref: /openbmc/linux/arch/mips/ralink/timer.c (revision 159c610a)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Ralink RT2880 timer
4  * Author: John Crispin
5  *
6  * Copyright (C) 2013 John Crispin <john@phrozen.org>
7 */
8 
9 #include <linux/platform_device.h>
10 #include <linux/interrupt.h>
11 #include <linux/timer.h>
12 #include <linux/of_gpio.h>
13 #include <linux/clk.h>
14 
15 #include <asm/mach-ralink/ralink_regs.h>
16 
17 #define TIMER_REG_TMRSTAT		0x00
18 #define TIMER_REG_TMR0LOAD		0x10
19 #define TIMER_REG_TMR0CTL		0x18
20 
21 #define TMRSTAT_TMR0INT			BIT(0)
22 
23 #define TMR0CTL_ENABLE			BIT(7)
24 #define TMR0CTL_MODE_PERIODIC		BIT(4)
25 #define TMR0CTL_PRESCALER		1
26 #define TMR0CTL_PRESCALE_VAL		(0xf - TMR0CTL_PRESCALER)
27 #define TMR0CTL_PRESCALE_DIV		(65536 / BIT(TMR0CTL_PRESCALER))
28 
29 struct rt_timer {
30 	struct device	*dev;
31 	void __iomem	*membase;
32 	int		irq;
33 	unsigned long	timer_freq;
34 	unsigned long	timer_div;
35 };
36 
rt_timer_w32(struct rt_timer * rt,u8 reg,u32 val)37 static inline void rt_timer_w32(struct rt_timer *rt, u8 reg, u32 val)
38 {
39 	__raw_writel(val, rt->membase + reg);
40 }
41 
rt_timer_r32(struct rt_timer * rt,u8 reg)42 static inline u32 rt_timer_r32(struct rt_timer *rt, u8 reg)
43 {
44 	return __raw_readl(rt->membase + reg);
45 }
46 
rt_timer_irq(int irq,void * _rt)47 static irqreturn_t rt_timer_irq(int irq, void *_rt)
48 {
49 	struct rt_timer *rt =  (struct rt_timer *) _rt;
50 
51 	rt_timer_w32(rt, TIMER_REG_TMR0LOAD, rt->timer_freq / rt->timer_div);
52 	rt_timer_w32(rt, TIMER_REG_TMRSTAT, TMRSTAT_TMR0INT);
53 
54 	return IRQ_HANDLED;
55 }
56 
57 
rt_timer_request(struct rt_timer * rt)58 static int rt_timer_request(struct rt_timer *rt)
59 {
60 	int err = request_irq(rt->irq, rt_timer_irq, 0,
61 						dev_name(rt->dev), rt);
62 	if (err) {
63 		dev_err(rt->dev, "failed to request irq\n");
64 	} else {
65 		u32 t = TMR0CTL_MODE_PERIODIC | TMR0CTL_PRESCALE_VAL;
66 		rt_timer_w32(rt, TIMER_REG_TMR0CTL, t);
67 	}
68 	return err;
69 }
70 
rt_timer_config(struct rt_timer * rt,unsigned long divisor)71 static int rt_timer_config(struct rt_timer *rt, unsigned long divisor)
72 {
73 	if (rt->timer_freq < divisor)
74 		rt->timer_div = rt->timer_freq;
75 	else
76 		rt->timer_div = divisor;
77 
78 	rt_timer_w32(rt, TIMER_REG_TMR0LOAD, rt->timer_freq / rt->timer_div);
79 
80 	return 0;
81 }
82 
rt_timer_enable(struct rt_timer * rt)83 static int rt_timer_enable(struct rt_timer *rt)
84 {
85 	u32 t;
86 
87 	rt_timer_w32(rt, TIMER_REG_TMR0LOAD, rt->timer_freq / rt->timer_div);
88 
89 	t = rt_timer_r32(rt, TIMER_REG_TMR0CTL);
90 	t |= TMR0CTL_ENABLE;
91 	rt_timer_w32(rt, TIMER_REG_TMR0CTL, t);
92 
93 	return 0;
94 }
95 
rt_timer_probe(struct platform_device * pdev)96 static int rt_timer_probe(struct platform_device *pdev)
97 {
98 	struct rt_timer *rt;
99 	struct clk *clk;
100 
101 	rt = devm_kzalloc(&pdev->dev, sizeof(*rt), GFP_KERNEL);
102 	if (!rt) {
103 		dev_err(&pdev->dev, "failed to allocate memory\n");
104 		return -ENOMEM;
105 	}
106 
107 	rt->irq = platform_get_irq(pdev, 0);
108 	if (rt->irq < 0)
109 		return rt->irq;
110 
111 	rt->membase = devm_platform_get_and_ioremap_resource(pdev, 0, NULL);
112 	if (IS_ERR(rt->membase))
113 		return PTR_ERR(rt->membase);
114 
115 	clk = devm_clk_get(&pdev->dev, NULL);
116 	if (IS_ERR(clk)) {
117 		dev_err(&pdev->dev, "failed get clock rate\n");
118 		return PTR_ERR(clk);
119 	}
120 
121 	rt->timer_freq = clk_get_rate(clk) / TMR0CTL_PRESCALE_DIV;
122 	if (!rt->timer_freq)
123 		return -EINVAL;
124 
125 	rt->dev = &pdev->dev;
126 	platform_set_drvdata(pdev, rt);
127 
128 	rt_timer_request(rt);
129 	rt_timer_config(rt, 2);
130 	rt_timer_enable(rt);
131 
132 	dev_info(&pdev->dev, "maximum frequency is %luHz\n", rt->timer_freq);
133 
134 	return 0;
135 }
136 
137 static const struct of_device_id rt_timer_match[] = {
138 	{ .compatible = "ralink,rt2880-timer" },
139 	{},
140 };
141 
142 static struct platform_driver rt_timer_driver = {
143 	.probe = rt_timer_probe,
144 	.driver = {
145 		.name			= "rt-timer",
146 		.of_match_table		= rt_timer_match,
147 		.suppress_bind_attrs	= true,
148 	},
149 };
150 builtin_platform_driver(rt_timer_driver);
151