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.
9 * Copyright (C) 2013 John Crispin <john@phrozen.org>
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>
18 #include <asm/mach-ralink/ralink_regs.h>
20 #define TIMER_REG_TMRSTAT 0x00
21 #define TIMER_REG_TMR0LOAD 0x10
22 #define TIMER_REG_TMR0CTL 0x18
24 #define TMRSTAT_TMR0INT BIT(0)
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))
34 void __iomem
*membase
;
36 unsigned long timer_freq
;
37 unsigned long timer_div
;
40 static inline void rt_timer_w32(struct rt_timer
*rt
, u8 reg
, u32 val
)
42 __raw_writel(val
, rt
->membase
+ reg
);
45 static inline u32
rt_timer_r32(struct rt_timer
*rt
, u8 reg
)
47 return __raw_readl(rt
->membase
+ reg
);
50 static irqreturn_t
rt_timer_irq(int irq
, void *_rt
)
52 struct rt_timer
*rt
= (struct rt_timer
*) _rt
;
54 rt_timer_w32(rt
, TIMER_REG_TMR0LOAD
, rt
->timer_freq
/ rt
->timer_div
);
55 rt_timer_w32(rt
, TIMER_REG_TMRSTAT
, TMRSTAT_TMR0INT
);
61 static int rt_timer_request(struct rt_timer
*rt
)
63 int err
= request_irq(rt
->irq
, rt_timer_irq
, 0,
64 dev_name(rt
->dev
), rt
);
66 dev_err(rt
->dev
, "failed to request irq\n");
68 u32 t
= TMR0CTL_MODE_PERIODIC
| TMR0CTL_PRESCALE_VAL
;
69 rt_timer_w32(rt
, TIMER_REG_TMR0CTL
, t
);
74 static void rt_timer_free(struct rt_timer
*rt
)
76 free_irq(rt
->irq
, rt
);
79 static int rt_timer_config(struct rt_timer
*rt
, unsigned long divisor
)
81 if (rt
->timer_freq
< divisor
)
82 rt
->timer_div
= rt
->timer_freq
;
84 rt
->timer_div
= divisor
;
86 rt_timer_w32(rt
, TIMER_REG_TMR0LOAD
, rt
->timer_freq
/ rt
->timer_div
);
91 static int rt_timer_enable(struct rt_timer
*rt
)
95 rt_timer_w32(rt
, TIMER_REG_TMR0LOAD
, rt
->timer_freq
/ rt
->timer_div
);
97 t
= rt_timer_r32(rt
, TIMER_REG_TMR0CTL
);
99 rt_timer_w32(rt
, TIMER_REG_TMR0CTL
, t
);
104 static void rt_timer_disable(struct rt_timer
*rt
)
108 t
= rt_timer_r32(rt
, TIMER_REG_TMR0CTL
);
109 t
&= ~TMR0CTL_ENABLE
;
110 rt_timer_w32(rt
, TIMER_REG_TMR0CTL
, t
);
113 static int rt_timer_probe(struct platform_device
*pdev
)
115 struct resource
*res
= platform_get_resource(pdev
, IORESOURCE_MEM
, 0);
119 rt
= devm_kzalloc(&pdev
->dev
, sizeof(*rt
), GFP_KERNEL
);
121 dev_err(&pdev
->dev
, "failed to allocate memory\n");
125 rt
->irq
= platform_get_irq(pdev
, 0);
127 dev_err(&pdev
->dev
, "failed to load irq\n");
131 rt
->membase
= devm_ioremap_resource(&pdev
->dev
, res
);
132 if (IS_ERR(rt
->membase
))
133 return PTR_ERR(rt
->membase
);
135 clk
= devm_clk_get(&pdev
->dev
, NULL
);
137 dev_err(&pdev
->dev
, "failed get clock rate\n");
141 rt
->timer_freq
= clk_get_rate(clk
) / TMR0CTL_PRESCALE_DIV
;
145 rt
->dev
= &pdev
->dev
;
146 platform_set_drvdata(pdev
, rt
);
148 rt_timer_request(rt
);
149 rt_timer_config(rt
, 2);
152 dev_info(&pdev
->dev
, "maximum frequency is %luHz\n", rt
->timer_freq
);
157 static const struct of_device_id rt_timer_match
[] = {
158 { .compatible
= "ralink,rt2880-timer" },
162 static struct platform_driver rt_timer_driver
= {
163 .probe
= rt_timer_probe
,
166 .of_match_table
= rt_timer_match
,
167 .suppress_bind_attrs
= true,
170 builtin_platform_driver(rt_timer_driver
);