1/*
2 * An RTC driver for the AVR32 AT32AP700x processor series.
3 *
4 * Copyright (C) 2007 Atmel Corporation
5 *
6 * This program is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License version 2 as published
8 * by the Free Software Foundation.
9 */
10
11#include <linux/module.h>
12#include <linux/kernel.h>
13#include <linux/platform_device.h>
14#include <linux/slab.h>
15#include <linux/rtc.h>
16#include <linux/io.h>
17
18/*
19 * This is a bare-bones RTC. It runs during most system sleep states, but has
20 * no battery backup and gets reset during system restart.  It must be
21 * initialized from an external clock (network, I2C, etc) before it can be of
22 * much use.
23 *
24 * The alarm functionality is limited by the hardware, not supporting
25 * periodic interrupts.
26 */
27
28#define RTC_CTRL		0x00
29#define RTC_CTRL_EN		   0
30#define RTC_CTRL_PCLR		   1
31#define RTC_CTRL_TOPEN		   2
32#define RTC_CTRL_PSEL		   8
33
34#define RTC_VAL			0x04
35
36#define RTC_TOP			0x08
37
38#define RTC_IER			0x10
39#define RTC_IER_TOPI		   0
40
41#define RTC_IDR			0x14
42#define RTC_IDR_TOPI		   0
43
44#define RTC_IMR			0x18
45#define RTC_IMR_TOPI		   0
46
47#define RTC_ISR			0x1c
48#define RTC_ISR_TOPI		   0
49
50#define RTC_ICR			0x20
51#define RTC_ICR_TOPI		   0
52
53#define RTC_BIT(name)		(1 << RTC_##name)
54#define RTC_BF(name, value)	((value) << RTC_##name)
55
56#define rtc_readl(dev, reg)				\
57	__raw_readl((dev)->regs + RTC_##reg)
58#define rtc_writel(dev, reg, value)			\
59	__raw_writel((value), (dev)->regs + RTC_##reg)
60
61struct rtc_at32ap700x {
62	struct rtc_device	*rtc;
63	void __iomem		*regs;
64	unsigned long		alarm_time;
65	unsigned long		irq;
66	/* Protect against concurrent register access. */
67	spinlock_t		lock;
68};
69
70static int at32_rtc_readtime(struct device *dev, struct rtc_time *tm)
71{
72	struct rtc_at32ap700x *rtc = dev_get_drvdata(dev);
73	unsigned long now;
74
75	now = rtc_readl(rtc, VAL);
76	rtc_time_to_tm(now, tm);
77
78	return 0;
79}
80
81static int at32_rtc_settime(struct device *dev, struct rtc_time *tm)
82{
83	struct rtc_at32ap700x *rtc = dev_get_drvdata(dev);
84	unsigned long now;
85	int ret;
86
87	ret = rtc_tm_to_time(tm, &now);
88	if (ret == 0)
89		rtc_writel(rtc, VAL, now);
90
91	return ret;
92}
93
94static int at32_rtc_readalarm(struct device *dev, struct rtc_wkalrm *alrm)
95{
96	struct rtc_at32ap700x *rtc = dev_get_drvdata(dev);
97
98	spin_lock_irq(&rtc->lock);
99	rtc_time_to_tm(rtc->alarm_time, &alrm->time);
100	alrm->enabled = rtc_readl(rtc, IMR) & RTC_BIT(IMR_TOPI) ? 1 : 0;
101	alrm->pending = rtc_readl(rtc, ISR) & RTC_BIT(ISR_TOPI) ? 1 : 0;
102	spin_unlock_irq(&rtc->lock);
103
104	return 0;
105}
106
107static int at32_rtc_setalarm(struct device *dev, struct rtc_wkalrm *alrm)
108{
109	struct rtc_at32ap700x *rtc = dev_get_drvdata(dev);
110	unsigned long rtc_unix_time;
111	unsigned long alarm_unix_time;
112	int ret;
113
114	rtc_unix_time = rtc_readl(rtc, VAL);
115
116	ret = rtc_tm_to_time(&alrm->time, &alarm_unix_time);
117	if (ret)
118		return ret;
119
120	if (alarm_unix_time < rtc_unix_time)
121		return -EINVAL;
122
123	spin_lock_irq(&rtc->lock);
124	rtc->alarm_time = alarm_unix_time;
125	rtc_writel(rtc, TOP, rtc->alarm_time);
126	if (alrm->enabled)
127		rtc_writel(rtc, CTRL, rtc_readl(rtc, CTRL)
128				| RTC_BIT(CTRL_TOPEN));
129	else
130		rtc_writel(rtc, CTRL, rtc_readl(rtc, CTRL)
131				& ~RTC_BIT(CTRL_TOPEN));
132	spin_unlock_irq(&rtc->lock);
133
134	return ret;
135}
136
137static int at32_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
138{
139	struct rtc_at32ap700x *rtc = dev_get_drvdata(dev);
140	int ret = 0;
141
142	spin_lock_irq(&rtc->lock);
143
144	if (enabled) {
145		if (rtc_readl(rtc, VAL) > rtc->alarm_time) {
146			ret = -EINVAL;
147			goto out;
148		}
149		rtc_writel(rtc, CTRL, rtc_readl(rtc, CTRL)
150				| RTC_BIT(CTRL_TOPEN));
151		rtc_writel(rtc, ICR, RTC_BIT(ICR_TOPI));
152		rtc_writel(rtc, IER, RTC_BIT(IER_TOPI));
153	} else {
154		rtc_writel(rtc, CTRL, rtc_readl(rtc, CTRL)
155				& ~RTC_BIT(CTRL_TOPEN));
156		rtc_writel(rtc, IDR, RTC_BIT(IDR_TOPI));
157		rtc_writel(rtc, ICR, RTC_BIT(ICR_TOPI));
158	}
159out:
160	spin_unlock_irq(&rtc->lock);
161
162	return ret;
163}
164
165static irqreturn_t at32_rtc_interrupt(int irq, void *dev_id)
166{
167	struct rtc_at32ap700x *rtc = (struct rtc_at32ap700x *)dev_id;
168	unsigned long isr = rtc_readl(rtc, ISR);
169	unsigned long events = 0;
170	int ret = IRQ_NONE;
171
172	spin_lock(&rtc->lock);
173
174	if (isr & RTC_BIT(ISR_TOPI)) {
175		rtc_writel(rtc, ICR, RTC_BIT(ICR_TOPI));
176		rtc_writel(rtc, IDR, RTC_BIT(IDR_TOPI));
177		rtc_writel(rtc, CTRL, rtc_readl(rtc, CTRL)
178				& ~RTC_BIT(CTRL_TOPEN));
179		rtc_writel(rtc, VAL, rtc->alarm_time);
180		events = RTC_AF | RTC_IRQF;
181		rtc_update_irq(rtc->rtc, 1, events);
182		ret = IRQ_HANDLED;
183	}
184
185	spin_unlock(&rtc->lock);
186
187	return ret;
188}
189
190static struct rtc_class_ops at32_rtc_ops = {
191	.read_time	= at32_rtc_readtime,
192	.set_time	= at32_rtc_settime,
193	.read_alarm	= at32_rtc_readalarm,
194	.set_alarm	= at32_rtc_setalarm,
195	.alarm_irq_enable = at32_rtc_alarm_irq_enable,
196};
197
198static int __init at32_rtc_probe(struct platform_device *pdev)
199{
200	struct resource	*regs;
201	struct rtc_at32ap700x *rtc;
202	int irq;
203	int ret;
204
205	rtc = devm_kzalloc(&pdev->dev, sizeof(struct rtc_at32ap700x),
206			   GFP_KERNEL);
207	if (!rtc)
208		return -ENOMEM;
209
210	regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
211	if (!regs) {
212		dev_dbg(&pdev->dev, "no mmio resource defined\n");
213		return -ENXIO;
214	}
215
216	irq = platform_get_irq(pdev, 0);
217	if (irq <= 0) {
218		dev_dbg(&pdev->dev, "could not get irq\n");
219		return -ENXIO;
220	}
221
222	rtc->irq = irq;
223	rtc->regs = devm_ioremap(&pdev->dev, regs->start, resource_size(regs));
224	if (!rtc->regs) {
225		dev_dbg(&pdev->dev, "could not map I/O memory\n");
226		return -ENOMEM;
227	}
228	spin_lock_init(&rtc->lock);
229
230	/*
231	 * Maybe init RTC: count from zero at 1 Hz, disable wrap irq.
232	 *
233	 * Do not reset VAL register, as it can hold an old time
234	 * from last JTAG reset.
235	 */
236	if (!(rtc_readl(rtc, CTRL) & RTC_BIT(CTRL_EN))) {
237		rtc_writel(rtc, CTRL, RTC_BIT(CTRL_PCLR));
238		rtc_writel(rtc, IDR, RTC_BIT(IDR_TOPI));
239		rtc_writel(rtc, CTRL, RTC_BF(CTRL_PSEL, 0xe)
240				| RTC_BIT(CTRL_EN));
241	}
242
243	ret = devm_request_irq(&pdev->dev, irq, at32_rtc_interrupt, IRQF_SHARED,
244				"rtc", rtc);
245	if (ret) {
246		dev_dbg(&pdev->dev, "could not request irq %d\n", irq);
247		return ret;
248	}
249
250	platform_set_drvdata(pdev, rtc);
251
252	rtc->rtc = devm_rtc_device_register(&pdev->dev, pdev->name,
253				&at32_rtc_ops, THIS_MODULE);
254	if (IS_ERR(rtc->rtc)) {
255		dev_dbg(&pdev->dev, "could not register rtc device\n");
256		return PTR_ERR(rtc->rtc);
257	}
258
259	device_init_wakeup(&pdev->dev, 1);
260
261	dev_info(&pdev->dev, "Atmel RTC for AT32AP700x at %08lx irq %ld\n",
262			(unsigned long)rtc->regs, rtc->irq);
263
264	return 0;
265}
266
267static int __exit at32_rtc_remove(struct platform_device *pdev)
268{
269	device_init_wakeup(&pdev->dev, 0);
270
271	return 0;
272}
273
274MODULE_ALIAS("platform:at32ap700x_rtc");
275
276static struct platform_driver at32_rtc_driver = {
277	.remove		= __exit_p(at32_rtc_remove),
278	.driver		= {
279		.name	= "at32ap700x_rtc",
280	},
281};
282
283module_platform_driver_probe(at32_rtc_driver, at32_rtc_probe);
284
285MODULE_AUTHOR("Hans-Christian Egtvedt <hcegtvedt@atmel.com>");
286MODULE_DESCRIPTION("Real time clock for AVR32 AT32AP700x");
287MODULE_LICENSE("GPL");
288