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 | |
37 | static inline void rt_timer_w32(struct rt_timer *rt, u8 reg, u32 val) |
38 | { |
39 | __raw_writel(val, addr: rt->membase + reg); |
40 | } |
41 | |
42 | static inline u32 rt_timer_r32(struct rt_timer *rt, u8 reg) |
43 | { |
44 | return __raw_readl(addr: rt->membase + reg); |
45 | } |
46 | |
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, val: rt->timer_freq / rt->timer_div); |
52 | rt_timer_w32(rt, TIMER_REG_TMRSTAT, TMRSTAT_TMR0INT); |
53 | |
54 | return IRQ_HANDLED; |
55 | } |
56 | |
57 | |
58 | static int rt_timer_request(struct rt_timer *rt) |
59 | { |
60 | int err = request_irq(irq: rt->irq, handler: rt_timer_irq, flags: 0, |
61 | name: dev_name(dev: rt->dev), 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, val: t); |
67 | } |
68 | return err; |
69 | } |
70 | |
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, val: rt->timer_freq / rt->timer_div); |
79 | |
80 | return 0; |
81 | } |
82 | |
83 | static int rt_timer_enable(struct rt_timer *rt) |
84 | { |
85 | u32 t; |
86 | |
87 | rt_timer_w32(rt, TIMER_REG_TMR0LOAD, val: 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, val: t); |
92 | |
93 | return 0; |
94 | } |
95 | |
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(dev: &pdev->dev, size: 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, index: 0, NULL); |
112 | if (IS_ERR(ptr: rt->membase)) |
113 | return PTR_ERR(ptr: rt->membase); |
114 | |
115 | clk = devm_clk_get(dev: &pdev->dev, NULL); |
116 | if (IS_ERR(ptr: clk)) { |
117 | dev_err(&pdev->dev, "failed get clock rate\n" ); |
118 | return PTR_ERR(ptr: 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, data: rt); |
127 | |
128 | rt_timer_request(rt); |
129 | rt_timer_config(rt, divisor: 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 | |