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
 29struct 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
 37static inline void rt_timer_w32(struct rt_timer *rt, u8 reg, u32 val)
 38{
 39	__raw_writel(val, rt->membase + reg);
 40}
 41
 42static inline u32 rt_timer_r32(struct rt_timer *rt, u8 reg)
 43{
 44	return __raw_readl(rt->membase + reg);
 45}
 46
 47static 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
 58static 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
 71static 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
 83static 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
 96static int rt_timer_probe(struct platform_device *pdev)
 97{
 98	struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 99	struct rt_timer *rt;
100	struct clk *clk;
101
102	rt = devm_kzalloc(&pdev->dev, sizeof(*rt), GFP_KERNEL);
103	if (!rt) {
104		dev_err(&pdev->dev, "failed to allocate memory\n");
105		return -ENOMEM;
106	}
107
108	rt->irq = platform_get_irq(pdev, 0);
109	if (rt->irq < 0)
110		return rt->irq;
111
112	rt->membase = devm_ioremap_resource(&pdev->dev, res);
113	if (IS_ERR(rt->membase))
114		return PTR_ERR(rt->membase);
115
116	clk = devm_clk_get(&pdev->dev, NULL);
117	if (IS_ERR(clk)) {
118		dev_err(&pdev->dev, "failed get clock rate\n");
119		return PTR_ERR(clk);
120	}
121
122	rt->timer_freq = clk_get_rate(clk) / TMR0CTL_PRESCALE_DIV;
123	if (!rt->timer_freq)
124		return -EINVAL;
125
126	rt->dev = &pdev->dev;
127	platform_set_drvdata(pdev, rt);
128
129	rt_timer_request(rt);
130	rt_timer_config(rt, 2);
131	rt_timer_enable(rt);
132
133	dev_info(&pdev->dev, "maximum frequency is %luHz\n", rt->timer_freq);
134
135	return 0;
136}
137
138static const struct of_device_id rt_timer_match[] = {
139	{ .compatible = "ralink,rt2880-timer" },
140	{},
141};
142
143static struct platform_driver rt_timer_driver = {
144	.probe = rt_timer_probe,
145	.driver = {
146		.name			= "rt-timer",
147		.of_match_table		= rt_timer_match,
148		.suppress_bind_attrs	= true,
149	},
150};
151builtin_platform_driver(rt_timer_driver);