MIPS: ralink: Add support for periodic timer irq

# Copyright (C) 2009-2011 Gabor Juhos <juhosg@openwrt.org>

# Copyright (C) 2013 John Crispin <blogic@openwrt.org>

obj-y := prom.o of.o reset.o clk.o irq.o

obj-y := prom.o of.o reset.o clk.o irq.o timer.o

obj-$(CONFIG_SOC_RT288X) += rt288x.o

obj-$(CONFIG_SOC_RT305X) += rt305x.o

/*

 * This program is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 as published

 * by the Free Software Foundation.

 *

 * Copyright (C) 2013 John Crispin <blogic@openwrt.org>

*/

#include <linux/module.h>

#include <linux/platform_device.h>

#include <linux/interrupt.h>

#include <linux/timer.h>

#include <linux/of_gpio.h>

#include <linux/clk.h>

#include <asm/mach-ralink/ralink_regs.h>

#define TIMER_REG_TMRSTAT		0x00

#define TIMER_REG_TMR0LOAD		0x10

#define TIMER_REG_TMR0CTL		0x18

#define TMRSTAT_TMR0INT			BIT(0)

#define TMR0CTL_ENABLE			BIT(7)

#define TMR0CTL_MODE_PERIODIC		BIT(4)

#define TMR0CTL_PRESCALER		1

#define TMR0CTL_PRESCALE_VAL		(0xf - TMR0CTL_PRESCALER)

#define TMR0CTL_PRESCALE_DIV		(65536 / BIT(TMR0CTL_PRESCALER))

struct rt_timer {

	struct device	*dev;

	void __iomem	*membase;

	int		irq;

	unsigned long	timer_freq;

	unsigned long	timer_div;

};

static inline void rt_timer_w32(struct rt_timer *rt, u8 reg, u32 val)

{

	__raw_writel(val, rt->membase + reg);

}

static inline u32 rt_timer_r32(struct rt_timer *rt, u8 reg)

{

	return __raw_readl(rt->membase + reg);

}

static irqreturn_t rt_timer_irq(int irq, void *_rt)

{

	struct rt_timer *rt =  (struct rt_timer *) _rt;

	rt_timer_w32(rt, TIMER_REG_TMR0LOAD, rt->timer_freq / rt->timer_div);

	rt_timer_w32(rt, TIMER_REG_TMRSTAT, TMRSTAT_TMR0INT);

	return IRQ_HANDLED;

}

static int rt_timer_request(struct rt_timer *rt)

{

	int err = request_irq(rt->irq, rt_timer_irq, IRQF_DISABLED,

						dev_name(rt->dev), rt);

	if (err) {

		dev_err(rt->dev, "failed to request irq\n");

	} else {

		u32 t = TMR0CTL_MODE_PERIODIC | TMR0CTL_PRESCALE_VAL;

		rt_timer_w32(rt, TIMER_REG_TMR0CTL, t);

	}

	return err;

}

static void rt_timer_free(struct rt_timer *rt)

{

	free_irq(rt->irq, rt);

}

static int rt_timer_config(struct rt_timer *rt, unsigned long divisor)

{

	if (rt->timer_freq < divisor)

		rt->timer_div = rt->timer_freq;

	else

		rt->timer_div = divisor;

	rt_timer_w32(rt, TIMER_REG_TMR0LOAD, rt->timer_freq / rt->timer_div);

	return 0;

}

static int rt_timer_enable(struct rt_timer *rt)

{

	u32 t;

	rt_timer_w32(rt, TIMER_REG_TMR0LOAD, rt->timer_freq / rt->timer_div);

	t = rt_timer_r32(rt, TIMER_REG_TMR0CTL);

	t |= TMR0CTL_ENABLE;

	rt_timer_w32(rt, TIMER_REG_TMR0CTL, t);

	return 0;

}

static void rt_timer_disable(struct rt_timer *rt)

{

	u32 t;

	t = rt_timer_r32(rt, TIMER_REG_TMR0CTL);

	t &= ~TMR0CTL_ENABLE;

	rt_timer_w32(rt, TIMER_REG_TMR0CTL, t);

}

static int rt_timer_probe(struct platform_device *pdev)

{

	struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0);

	struct rt_timer *rt;

	struct clk *clk;

	rt = devm_kzalloc(&pdev->dev, sizeof(*rt), GFP_KERNEL);

	if (!rt) {

		dev_err(&pdev->dev, "failed to allocate memory\n");

		return -ENOMEM;

	}

	rt->irq = platform_get_irq(pdev, 0);

	if (!rt->irq) {

		dev_err(&pdev->dev, "failed to load irq\n");

		return -ENOENT;

	}

	rt->membase = devm_request_and_ioremap(&pdev->dev, res);

	if (IS_ERR(rt->membase))

		return PTR_ERR(rt->membase);

	clk = devm_clk_get(&pdev->dev, NULL);

	if (IS_ERR(clk)) {

		dev_err(&pdev->dev, "failed get clock rate\n");

		return PTR_ERR(clk);

	}

	rt->timer_freq = clk_get_rate(clk) / TMR0CTL_PRESCALE_DIV;

	if (!rt->timer_freq)

		return -EINVAL;

	rt->dev = &pdev->dev;

	platform_set_drvdata(pdev, rt);

	rt_timer_request(rt);

	rt_timer_config(rt, 2);

	rt_timer_enable(rt);

	dev_info(&pdev->dev, "maximum frequncy is %luHz\n", rt->timer_freq);

	return 0;

}

static int rt_timer_remove(struct platform_device *pdev)

{

	struct rt_timer *rt = platform_get_drvdata(pdev);

	rt_timer_disable(rt);

	rt_timer_free(rt);

	return 0;

}

static const struct of_device_id rt_timer_match[] = {

	{ .compatible = "ralink,rt2880-timer" },

	{},

};

MODULE_DEVICE_TABLE(of, rt_timer_match);

static struct platform_driver rt_timer_driver = {

	.probe = rt_timer_probe,

	.remove = rt_timer_remove,

	.driver = {

		.name		= "rt-timer",

		.owner          = THIS_MODULE,

		.of_match_table	= rt_timer_match

	},

};

module_platform_driver(rt_timer_driver);

MODULE_DESCRIPTION("Ralink RT2880 timer");

MODULE_AUTHOR("John Crispin <blogic@openwrt.org");

MODULE_LICENSE("GPL");