1/*
  2 *  linux/drivers/clocksource/zevio-timer.c
  3 *
  4 *  Copyright (C) 2013 Daniel Tang <tangrs@tangrs.id.au>
  5 *
  6 * This program is free software; you can redistribute it and/or modify
  7 * it under the terms of the GNU General Public License version 2, as
  8 * published by the Free Software Foundation.
  9 *
 10 */
 11
 12#include <linux/io.h>
 13#include <linux/irq.h>
 14#include <linux/of.h>
 15#include <linux/of_address.h>
 16#include <linux/of_irq.h>
 17#include <linux/clk.h>
 18#include <linux/clockchips.h>
 19#include <linux/cpumask.h>
 20#include <linux/interrupt.h>
 21#include <linux/slab.h>
 22
 23#define IO_CURRENT_VAL	0x00
 24#define IO_DIVIDER	0x04
 25#define IO_CONTROL	0x08
 26
 27#define IO_TIMER1	0x00
 28#define IO_TIMER2	0x0C
 29
 30#define IO_MATCH_BEGIN	0x18
 31#define IO_MATCH(x)	(IO_MATCH_BEGIN + ((x) << 2))
 32
 33#define IO_INTR_STS	0x00
 34#define IO_INTR_ACK	0x00
 35#define IO_INTR_MSK	0x04
 36
 37#define CNTL_STOP_TIMER	(1 << 4)
 38#define CNTL_RUN_TIMER	(0 << 4)
 39
 40#define CNTL_INC	(1 << 3)
 41#define CNTL_DEC	(0 << 3)
 42
 43#define CNTL_TOZERO	0
 44#define CNTL_MATCH(x)	((x) + 1)
 45#define CNTL_FOREVER	7
 46
 47/* There are 6 match registers but we only use one. */
 48#define TIMER_MATCH	0
 49
 50#define TIMER_INTR_MSK	(1 << (TIMER_MATCH))
 51#define TIMER_INTR_ALL	0x3F
 52
 53struct zevio_timer {
 54	void __iomem *base;
 55	void __iomem *timer1, *timer2;
 56	void __iomem *interrupt_regs;
 57
 58	struct clk *clk;
 59	struct clock_event_device clkevt;
 60	struct irqaction clkevt_irq;
 61
 62	char clocksource_name[64];
 63	char clockevent_name[64];
 64};
 65
 66static int zevio_timer_set_event(unsigned long delta,
 67				 struct clock_event_device *dev)
 68{
 69	struct zevio_timer *timer = container_of(dev, struct zevio_timer,
 70						 clkevt);
 71
 72	writel(delta, timer->timer1 + IO_CURRENT_VAL);
 73	writel(CNTL_RUN_TIMER | CNTL_DEC | CNTL_MATCH(TIMER_MATCH),
 74			timer->timer1 + IO_CONTROL);
 75
 76	return 0;
 77}
 78
 79static int zevio_timer_shutdown(struct clock_event_device *dev)
 80{
 81	struct zevio_timer *timer = container_of(dev, struct zevio_timer,
 82						 clkevt);
 83
 84	/* Disable timer interrupts */
 85	writel(0, timer->interrupt_regs + IO_INTR_MSK);
 86	writel(TIMER_INTR_ALL, timer->interrupt_regs + IO_INTR_ACK);
 87	/* Stop timer */
 88	writel(CNTL_STOP_TIMER, timer->timer1 + IO_CONTROL);
 89	return 0;
 90}
 91
 92static int zevio_timer_set_oneshot(struct clock_event_device *dev)
 93{
 94	struct zevio_timer *timer = container_of(dev, struct zevio_timer,
 95						 clkevt);
 96
 97	/* Enable timer interrupts */
 98	writel(TIMER_INTR_MSK, timer->interrupt_regs + IO_INTR_MSK);
 99	writel(TIMER_INTR_ALL, timer->interrupt_regs + IO_INTR_ACK);
100	return 0;
101}
102
103static irqreturn_t zevio_timer_interrupt(int irq, void *dev_id)
104{
105	struct zevio_timer *timer = dev_id;
106	u32 intr;
107
108	intr = readl(timer->interrupt_regs + IO_INTR_ACK);
109	if (!(intr & TIMER_INTR_MSK))
110		return IRQ_NONE;
111
112	writel(TIMER_INTR_MSK, timer->interrupt_regs + IO_INTR_ACK);
113	writel(CNTL_STOP_TIMER, timer->timer1 + IO_CONTROL);
114
115	if (timer->clkevt.event_handler)
116		timer->clkevt.event_handler(&timer->clkevt);
117
118	return IRQ_HANDLED;
119}
120
121static int __init zevio_timer_add(struct device_node *node)
122{
123	struct zevio_timer *timer;
124	struct resource res;
125	int irqnr, ret;
126
127	timer = kzalloc(sizeof(*timer), GFP_KERNEL);
128	if (!timer)
129		return -ENOMEM;
130
131	timer->base = of_iomap(node, 0);
132	if (!timer->base) {
133		ret = -EINVAL;
134		goto error_free;
135	}
136	timer->timer1 = timer->base + IO_TIMER1;
137	timer->timer2 = timer->base + IO_TIMER2;
138
139	timer->clk = of_clk_get(node, 0);
140	if (IS_ERR(timer->clk)) {
141		ret = PTR_ERR(timer->clk);
142		pr_err("Timer clock not found! (error %d)\n", ret);
143		goto error_unmap;
144	}
145
146	timer->interrupt_regs = of_iomap(node, 1);
147	irqnr = irq_of_parse_and_map(node, 0);
148
149	of_address_to_resource(node, 0, &res);
150	scnprintf(timer->clocksource_name, sizeof(timer->clocksource_name),
151			"%llx.%s_clocksource",
152			(unsigned long long)res.start, node->name);
153
154	scnprintf(timer->clockevent_name, sizeof(timer->clockevent_name),
155			"%llx.%s_clockevent",
156			(unsigned long long)res.start, node->name);
157
158	if (timer->interrupt_regs && irqnr) {
159		timer->clkevt.name		= timer->clockevent_name;
160		timer->clkevt.set_next_event	= zevio_timer_set_event;
161		timer->clkevt.set_state_shutdown = zevio_timer_shutdown;
162		timer->clkevt.set_state_oneshot = zevio_timer_set_oneshot;
163		timer->clkevt.tick_resume	= zevio_timer_set_oneshot;
164		timer->clkevt.rating		= 200;
165		timer->clkevt.cpumask		= cpu_all_mask;
166		timer->clkevt.features		= CLOCK_EVT_FEAT_ONESHOT;
167		timer->clkevt.irq		= irqnr;
168
169		writel(CNTL_STOP_TIMER, timer->timer1 + IO_CONTROL);
170		writel(0, timer->timer1 + IO_DIVIDER);
171
172		/* Start with timer interrupts disabled */
173		writel(0, timer->interrupt_regs + IO_INTR_MSK);
174		writel(TIMER_INTR_ALL, timer->interrupt_regs + IO_INTR_ACK);
175
176		/* Interrupt to occur when timer value matches 0 */
177		writel(0, timer->base + IO_MATCH(TIMER_MATCH));
178
179		timer->clkevt_irq.name		= timer->clockevent_name;
180		timer->clkevt_irq.handler	= zevio_timer_interrupt;
181		timer->clkevt_irq.dev_id	= timer;
182		timer->clkevt_irq.flags		= IRQF_TIMER | IRQF_IRQPOLL;
183
184		setup_irq(irqnr, &timer->clkevt_irq);
185
186		clockevents_config_and_register(&timer->clkevt,
187				clk_get_rate(timer->clk), 0x0001, 0xffff);
188		pr_info("Added %s as clockevent\n", timer->clockevent_name);
189	}
190
191	writel(CNTL_STOP_TIMER, timer->timer2 + IO_CONTROL);
192	writel(0, timer->timer2 + IO_CURRENT_VAL);
193	writel(0, timer->timer2 + IO_DIVIDER);
194	writel(CNTL_RUN_TIMER | CNTL_FOREVER | CNTL_INC,
195			timer->timer2 + IO_CONTROL);
196
197	clocksource_mmio_init(timer->timer2 + IO_CURRENT_VAL,
198			timer->clocksource_name,
199			clk_get_rate(timer->clk),
200			200, 16,
201			clocksource_mmio_readw_up);
202
203	pr_info("Added %s as clocksource\n", timer->clocksource_name);
204
205	return 0;
206error_unmap:
207	iounmap(timer->base);
208error_free:
209	kfree(timer);
210	return ret;
211}
212
213static void __init zevio_timer_init(struct device_node *node)
214{
215	BUG_ON(zevio_timer_add(node));
216}
217
218CLOCKSOURCE_OF_DECLARE(zevio_timer, "lsi,zevio-timer", zevio_timer_init);