1/*
2 * Mediatek SoCs General-Purpose Timer handling.
3 *
4 * Copyright (C) 2014 Matthias Brugger
5 *
6 * Matthias Brugger <matthias.bgg@gmail.com>
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation; either version 2 of the License, or
11 * (at your option) any later version.
12 *
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16 * GNU General Public License for more details.
17 */
18
19#include <linux/clk.h>
20#include <linux/clockchips.h>
21#include <linux/interrupt.h>
22#include <linux/irq.h>
23#include <linux/irqreturn.h>
24#include <linux/of.h>
25#include <linux/of_address.h>
26#include <linux/of_irq.h>
27#include <linux/slab.h>
28
29#define GPT_IRQ_EN_REG		0x00
30#define GPT_IRQ_ENABLE(val)	BIT((val) - 1)
31#define GPT_IRQ_ACK_REG		0x08
32#define GPT_IRQ_ACK(val)	BIT((val) - 1)
33
34#define TIMER_CTRL_REG(val)	(0x10 * (val))
35#define TIMER_CTRL_OP(val)	(((val) & 0x3) << 4)
36#define TIMER_CTRL_OP_ONESHOT	(0)
37#define TIMER_CTRL_OP_REPEAT	(1)
38#define TIMER_CTRL_OP_FREERUN	(3)
39#define TIMER_CTRL_CLEAR	(2)
40#define TIMER_CTRL_ENABLE	(1)
41#define TIMER_CTRL_DISABLE	(0)
42
43#define TIMER_CLK_REG(val)	(0x04 + (0x10 * (val)))
44#define TIMER_CLK_SRC(val)	(((val) & 0x1) << 4)
45#define TIMER_CLK_SRC_SYS13M	(0)
46#define TIMER_CLK_SRC_RTC32K	(1)
47#define TIMER_CLK_DIV1		(0x0)
48#define TIMER_CLK_DIV2		(0x1)
49
50#define TIMER_CNT_REG(val)	(0x08 + (0x10 * (val)))
51#define TIMER_CMP_REG(val)	(0x0C + (0x10 * (val)))
52
53#define GPT_CLK_EVT	1
54#define GPT_CLK_SRC	2
55
56struct mtk_clock_event_device {
57	void __iomem *gpt_base;
58	u32 ticks_per_jiffy;
59	struct clock_event_device dev;
60};
61
62static inline struct mtk_clock_event_device *to_mtk_clk(
63				struct clock_event_device *c)
64{
65	return container_of(c, struct mtk_clock_event_device, dev);
66}
67
68static void mtk_clkevt_time_stop(struct mtk_clock_event_device *evt, u8 timer)
69{
70	u32 val;
71
72	val = readl(evt->gpt_base + TIMER_CTRL_REG(timer));
73	writel(val & ~TIMER_CTRL_ENABLE, evt->gpt_base +
74			TIMER_CTRL_REG(timer));
75}
76
77static void mtk_clkevt_time_setup(struct mtk_clock_event_device *evt,
78				unsigned long delay, u8 timer)
79{
80	writel(delay, evt->gpt_base + TIMER_CMP_REG(timer));
81}
82
83static void mtk_clkevt_time_start(struct mtk_clock_event_device *evt,
84		bool periodic, u8 timer)
85{
86	u32 val;
87
88	/* Acknowledge interrupt */
89	writel(GPT_IRQ_ACK(timer), evt->gpt_base + GPT_IRQ_ACK_REG);
90
91	val = readl(evt->gpt_base + TIMER_CTRL_REG(timer));
92
93	/* Clear 2 bit timer operation mode field */
94	val &= ~TIMER_CTRL_OP(0x3);
95
96	if (periodic)
97		val |= TIMER_CTRL_OP(TIMER_CTRL_OP_REPEAT);
98	else
99		val |= TIMER_CTRL_OP(TIMER_CTRL_OP_ONESHOT);
100
101	writel(val | TIMER_CTRL_ENABLE | TIMER_CTRL_CLEAR,
102	       evt->gpt_base + TIMER_CTRL_REG(timer));
103}
104
105static void mtk_clkevt_mode(enum clock_event_mode mode,
106				struct clock_event_device *clk)
107{
108	struct mtk_clock_event_device *evt = to_mtk_clk(clk);
109
110	mtk_clkevt_time_stop(evt, GPT_CLK_EVT);
111
112	switch (mode) {
113	case CLOCK_EVT_MODE_PERIODIC:
114		mtk_clkevt_time_setup(evt, evt->ticks_per_jiffy, GPT_CLK_EVT);
115		mtk_clkevt_time_start(evt, true, GPT_CLK_EVT);
116		break;
117	case CLOCK_EVT_MODE_ONESHOT:
118		/* Timer is enabled in set_next_event */
119		break;
120	case CLOCK_EVT_MODE_UNUSED:
121	case CLOCK_EVT_MODE_SHUTDOWN:
122	default:
123		/* No more interrupts will occur as source is disabled */
124		break;
125	}
126}
127
128static int mtk_clkevt_next_event(unsigned long event,
129				   struct clock_event_device *clk)
130{
131	struct mtk_clock_event_device *evt = to_mtk_clk(clk);
132
133	mtk_clkevt_time_stop(evt, GPT_CLK_EVT);
134	mtk_clkevt_time_setup(evt, event, GPT_CLK_EVT);
135	mtk_clkevt_time_start(evt, false, GPT_CLK_EVT);
136
137	return 0;
138}
139
140static irqreturn_t mtk_timer_interrupt(int irq, void *dev_id)
141{
142	struct mtk_clock_event_device *evt = dev_id;
143
144	/* Acknowledge timer0 irq */
145	writel(GPT_IRQ_ACK(GPT_CLK_EVT), evt->gpt_base + GPT_IRQ_ACK_REG);
146	evt->dev.event_handler(&evt->dev);
147
148	return IRQ_HANDLED;
149}
150
151static void mtk_timer_global_reset(struct mtk_clock_event_device *evt)
152{
153	/* Disable all interrupts */
154	writel(0x0, evt->gpt_base + GPT_IRQ_EN_REG);
155	/* Acknowledge all interrupts */
156	writel(0x3f, evt->gpt_base + GPT_IRQ_ACK_REG);
157}
158
159static void
160mtk_timer_setup(struct mtk_clock_event_device *evt, u8 timer, u8 option)
161{
162	writel(TIMER_CTRL_CLEAR | TIMER_CTRL_DISABLE,
163		evt->gpt_base + TIMER_CTRL_REG(timer));
164
165	writel(TIMER_CLK_SRC(TIMER_CLK_SRC_SYS13M) | TIMER_CLK_DIV1,
166			evt->gpt_base + TIMER_CLK_REG(timer));
167
168	writel(0x0, evt->gpt_base + TIMER_CMP_REG(timer));
169
170	writel(TIMER_CTRL_OP(option) | TIMER_CTRL_ENABLE,
171			evt->gpt_base + TIMER_CTRL_REG(timer));
172}
173
174static void mtk_timer_enable_irq(struct mtk_clock_event_device *evt, u8 timer)
175{
176	u32 val;
177
178	val = readl(evt->gpt_base + GPT_IRQ_EN_REG);
179	writel(val | GPT_IRQ_ENABLE(timer),
180			evt->gpt_base + GPT_IRQ_EN_REG);
181}
182
183static void __init mtk_timer_init(struct device_node *node)
184{
185	struct mtk_clock_event_device *evt;
186	struct resource res;
187	unsigned long rate = 0;
188	struct clk *clk;
189
190	evt = kzalloc(sizeof(*evt), GFP_KERNEL);
191	if (!evt) {
192		pr_warn("Can't allocate mtk clock event driver struct");
193		return;
194	}
195
196	evt->dev.name = "mtk_tick";
197	evt->dev.rating = 300;
198	evt->dev.features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT;
199	evt->dev.set_mode = mtk_clkevt_mode;
200	evt->dev.set_next_event = mtk_clkevt_next_event;
201	evt->dev.cpumask = cpu_possible_mask;
202
203	evt->gpt_base = of_io_request_and_map(node, 0, "mtk-timer");
204	if (IS_ERR(evt->gpt_base)) {
205		pr_warn("Can't get resource\n");
206		return;
207	}
208
209	evt->dev.irq = irq_of_parse_and_map(node, 0);
210	if (evt->dev.irq <= 0) {
211		pr_warn("Can't parse IRQ");
212		goto err_mem;
213	}
214
215	clk = of_clk_get(node, 0);
216	if (IS_ERR(clk)) {
217		pr_warn("Can't get timer clock");
218		goto err_irq;
219	}
220
221	if (clk_prepare_enable(clk)) {
222		pr_warn("Can't prepare clock");
223		goto err_clk_put;
224	}
225	rate = clk_get_rate(clk);
226
227	mtk_timer_global_reset(evt);
228
229	if (request_irq(evt->dev.irq, mtk_timer_interrupt,
230			IRQF_TIMER | IRQF_IRQPOLL, "mtk_timer", evt)) {
231		pr_warn("failed to setup irq %d\n", evt->dev.irq);
232		goto err_clk_disable;
233	}
234
235	evt->ticks_per_jiffy = DIV_ROUND_UP(rate, HZ);
236
237	/* Configure clock source */
238	mtk_timer_setup(evt, GPT_CLK_SRC, TIMER_CTRL_OP_FREERUN);
239	clocksource_mmio_init(evt->gpt_base + TIMER_CNT_REG(GPT_CLK_SRC),
240			node->name, rate, 300, 32, clocksource_mmio_readl_up);
241
242	/* Configure clock event */
243	mtk_timer_setup(evt, GPT_CLK_EVT, TIMER_CTRL_OP_REPEAT);
244	clockevents_config_and_register(&evt->dev, rate, 0x3,
245					0xffffffff);
246
247	mtk_timer_enable_irq(evt, GPT_CLK_EVT);
248
249	return;
250
251err_clk_disable:
252	clk_disable_unprepare(clk);
253err_clk_put:
254	clk_put(clk);
255err_irq:
256	irq_dispose_mapping(evt->dev.irq);
257err_mem:
258	iounmap(evt->gpt_base);
259	of_address_to_resource(node, 0, &res);
260	release_mem_region(res.start, resource_size(&res));
261}
262CLOCKSOURCE_OF_DECLARE(mtk_mt6577, "mediatek,mt6577-timer", mtk_timer_init);
263