1// SPDX-License-Identifier: GPL-2.0
2/*
3 * IXP4 timer driver
4 * Copyright (C) 2019 Linus Walleij <linus.walleij@linaro.org>
5 *
6 * Based on arch/arm/mach-ixp4xx/common.c
7 * Copyright 2002 (C) Intel Corporation
8 * Copyright 2003-2004 (C) MontaVista, Software, Inc.
9 * Copyright (C) Deepak Saxena <dsaxena@plexity.net>
10 */
11#include <linux/interrupt.h>
12#include <linux/io.h>
13#include <linux/clockchips.h>
14#include <linux/clocksource.h>
15#include <linux/sched_clock.h>
16#include <linux/slab.h>
17#include <linux/bitops.h>
18#include <linux/delay.h>
19#include <linux/of_address.h>
20#include <linux/of_irq.h>
21#include <linux/platform_device.h>
22
23/*
24 * Constants to make it easy to access Timer Control/Status registers
25 */
26#define IXP4XX_OSTS_OFFSET	0x00  /* Continuous Timestamp */
27#define IXP4XX_OST1_OFFSET	0x04  /* Timer 1 Timestamp */
28#define IXP4XX_OSRT1_OFFSET	0x08  /* Timer 1 Reload */
29#define IXP4XX_OST2_OFFSET	0x0C  /* Timer 2 Timestamp */
30#define IXP4XX_OSRT2_OFFSET	0x10  /* Timer 2 Reload */
31#define IXP4XX_OSST_OFFSET	0x20  /* Timer Status */
32
33/*
34 * Timer register values and bit definitions
35 */
36#define IXP4XX_OST_ENABLE		0x00000001
37#define IXP4XX_OST_ONE_SHOT		0x00000002
38/* Low order bits of reload value ignored */
39#define IXP4XX_OST_RELOAD_MASK		0x00000003
40#define IXP4XX_OST_DISABLED		0x00000000
41#define IXP4XX_OSST_TIMER_1_PEND	0x00000001
42#define IXP4XX_OSST_TIMER_2_PEND	0x00000002
43#define IXP4XX_OSST_TIMER_TS_PEND	0x00000004
44/* Remaining registers are for the watchdog and defined in the watchdog driver */
45
46struct ixp4xx_timer {
47	void __iomem *base;
48	u32 latch;
49	struct clock_event_device clkevt;
50#ifdef CONFIG_ARM
51	struct delay_timer delay_timer;
52#endif
53};
54
55/*
56 * A local singleton used by sched_clock and delay timer reads, which are
57 * fast and stateless
58 */
59static struct ixp4xx_timer *local_ixp4xx_timer;
60
61static inline struct ixp4xx_timer *
62to_ixp4xx_timer(struct clock_event_device *evt)
63{
64	return container_of(evt, struct ixp4xx_timer, clkevt);
65}
66
67static unsigned long ixp4xx_read_timer(void)
68{
69	return __raw_readl(local_ixp4xx_timer->base + IXP4XX_OSTS_OFFSET);
70}
71
72static u64 notrace ixp4xx_read_sched_clock(void)
73{
74	return ixp4xx_read_timer();
75}
76
77static u64 ixp4xx_clocksource_read(struct clocksource *c)
78{
79	return ixp4xx_read_timer();
80}
81
82static irqreturn_t ixp4xx_timer_interrupt(int irq, void *dev_id)
83{
84	struct ixp4xx_timer *tmr = dev_id;
85	struct clock_event_device *evt = &tmr->clkevt;
86
87	/* Clear Pending Interrupt */
88	__raw_writel(IXP4XX_OSST_TIMER_1_PEND,
89		     tmr->base + IXP4XX_OSST_OFFSET);
90
91	evt->event_handler(evt);
92
93	return IRQ_HANDLED;
94}
95
96static int ixp4xx_set_next_event(unsigned long cycles,
97				 struct clock_event_device *evt)
98{
99	struct ixp4xx_timer *tmr = to_ixp4xx_timer(evt);
100	u32 val;
101
102	val = __raw_readl(tmr->base + IXP4XX_OSRT1_OFFSET);
103	/* Keep enable/oneshot bits */
104	val &= IXP4XX_OST_RELOAD_MASK;
105	__raw_writel((cycles & ~IXP4XX_OST_RELOAD_MASK) | val,
106		     tmr->base + IXP4XX_OSRT1_OFFSET);
107
108	return 0;
109}
110
111static int ixp4xx_shutdown(struct clock_event_device *evt)
112{
113	struct ixp4xx_timer *tmr = to_ixp4xx_timer(evt);
114	u32 val;
115
116	val = __raw_readl(tmr->base + IXP4XX_OSRT1_OFFSET);
117	val &= ~IXP4XX_OST_ENABLE;
118	__raw_writel(val, tmr->base + IXP4XX_OSRT1_OFFSET);
119
120	return 0;
121}
122
123static int ixp4xx_set_oneshot(struct clock_event_device *evt)
124{
125	struct ixp4xx_timer *tmr = to_ixp4xx_timer(evt);
126
127	__raw_writel(IXP4XX_OST_ENABLE | IXP4XX_OST_ONE_SHOT,
128		     tmr->base + IXP4XX_OSRT1_OFFSET);
129
130	return 0;
131}
132
133static int ixp4xx_set_periodic(struct clock_event_device *evt)
134{
135	struct ixp4xx_timer *tmr = to_ixp4xx_timer(evt);
136	u32 val;
137
138	val = tmr->latch & ~IXP4XX_OST_RELOAD_MASK;
139	val |= IXP4XX_OST_ENABLE;
140	__raw_writel(val, tmr->base + IXP4XX_OSRT1_OFFSET);
141
142	return 0;
143}
144
145static int ixp4xx_resume(struct clock_event_device *evt)
146{
147	struct ixp4xx_timer *tmr = to_ixp4xx_timer(evt);
148	u32 val;
149
150	val = __raw_readl(tmr->base + IXP4XX_OSRT1_OFFSET);
151	val |= IXP4XX_OST_ENABLE;
152	__raw_writel(val, tmr->base + IXP4XX_OSRT1_OFFSET);
153
154	return 0;
155}
156
157/*
158 * IXP4xx timer tick
159 * We use OS timer1 on the CPU for the timer tick and the timestamp
160 * counter as a source of real clock ticks to account for missed jiffies.
161 */
162static __init int ixp4xx_timer_register(void __iomem *base,
163					int timer_irq,
164					unsigned int timer_freq)
165{
166	struct ixp4xx_timer *tmr;
167	int ret;
168
169	tmr = kzalloc(sizeof(*tmr), GFP_KERNEL);
170	if (!tmr)
171		return -ENOMEM;
172	tmr->base = base;
173
174	/*
175	 * The timer register doesn't allow to specify the two least
176	 * significant bits of the timeout value and assumes them being zero.
177	 * So make sure the latch is the best value with the two least
178	 * significant bits unset.
179	 */
180	tmr->latch = DIV_ROUND_CLOSEST(timer_freq,
181				       (IXP4XX_OST_RELOAD_MASK + 1) * HZ)
182		* (IXP4XX_OST_RELOAD_MASK + 1);
183
184	local_ixp4xx_timer = tmr;
185
186	/* Reset/disable counter */
187	__raw_writel(0, tmr->base + IXP4XX_OSRT1_OFFSET);
188
189	/* Clear any pending interrupt on timer 1 */
190	__raw_writel(IXP4XX_OSST_TIMER_1_PEND,
191		     tmr->base + IXP4XX_OSST_OFFSET);
192
193	/* Reset time-stamp counter */
194	__raw_writel(0, tmr->base + IXP4XX_OSTS_OFFSET);
195
196	clocksource_mmio_init(NULL, "OSTS", timer_freq, 200, 32,
197			      ixp4xx_clocksource_read);
198
199	tmr->clkevt.name = "ixp4xx timer1";
200	tmr->clkevt.features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT;
201	tmr->clkevt.rating = 200;
202	tmr->clkevt.set_state_shutdown = ixp4xx_shutdown;
203	tmr->clkevt.set_state_periodic = ixp4xx_set_periodic;
204	tmr->clkevt.set_state_oneshot = ixp4xx_set_oneshot;
205	tmr->clkevt.tick_resume = ixp4xx_resume;
206	tmr->clkevt.set_next_event = ixp4xx_set_next_event;
207	tmr->clkevt.cpumask = cpumask_of(0);
208	tmr->clkevt.irq = timer_irq;
209	ret = request_irq(timer_irq, ixp4xx_timer_interrupt,
210			  IRQF_TIMER, "IXP4XX-TIMER1", tmr);
211	if (ret) {
212		pr_crit("no timer IRQ\n");
213		return -ENODEV;
214	}
215	clockevents_config_and_register(&tmr->clkevt, timer_freq,
216					0xf, 0xfffffffe);
217
218	sched_clock_register(ixp4xx_read_sched_clock, 32, timer_freq);
219
220#ifdef CONFIG_ARM
221	/* Also use this timer for delays */
222	tmr->delay_timer.read_current_timer = ixp4xx_read_timer;
223	tmr->delay_timer.freq = timer_freq;
224	register_current_timer_delay(&tmr->delay_timer);
225#endif
226
227	return 0;
228}
229
230static struct platform_device ixp4xx_watchdog_device = {
231	.name = "ixp4xx-watchdog",
232	.id = -1,
233};
234
235/*
236 * This probe gets called after the timer is already up and running. The main
237 * function on this platform is to spawn the watchdog device as a child.
238 */
239static int ixp4xx_timer_probe(struct platform_device *pdev)
240{
241	struct device *dev = &pdev->dev;
242
243	/* Pass the base address as platform data and nothing else */
244	ixp4xx_watchdog_device.dev.platform_data = local_ixp4xx_timer->base;
245	ixp4xx_watchdog_device.dev.parent = dev;
246	return platform_device_register(&ixp4xx_watchdog_device);
247}
248
249static const struct of_device_id ixp4xx_timer_dt_id[] = {
250	{ .compatible = "intel,ixp4xx-timer", },
251	{ /* sentinel */ },
252};
253
254static struct platform_driver ixp4xx_timer_driver = {
255	.probe  = ixp4xx_timer_probe,
256	.driver = {
257		.name = "ixp4xx-timer",
258		.of_match_table = ixp4xx_timer_dt_id,
259		.suppress_bind_attrs = true,
260	},
261};
262builtin_platform_driver(ixp4xx_timer_driver);
263
264static __init int ixp4xx_of_timer_init(struct device_node *np)
265{
266	void __iomem *base;
267	int irq;
268	int ret;
269
270	base = of_iomap(np, 0);
271	if (!base) {
272		pr_crit("IXP4xx: can't remap timer\n");
273		return -ENODEV;
274	}
275
276	irq = irq_of_parse_and_map(np, 0);
277	if (irq <= 0) {
278		pr_err("Can't parse IRQ\n");
279		ret = -EINVAL;
280		goto out_unmap;
281	}
282
283	/* TODO: get some fixed clocks into the device tree */
284	ret = ixp4xx_timer_register(base, irq, 66666000);
285	if (ret)
286		goto out_unmap;
287	return 0;
288
289out_unmap:
290	iounmap(base);
291	return ret;
292}
293TIMER_OF_DECLARE(ixp4xx, "intel,ixp4xx-timer", ixp4xx_of_timer_init);
294