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 = kzalloc(sizeof(struct rtc_at32ap700x), GFP_KERNEL);
206	if (!rtc) {
207		dev_dbg(&pdev->dev, "out of memory\n");
208		return -ENOMEM;
209	}
210
211	regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
212	if (!regs) {
213		dev_dbg(&pdev->dev, "no mmio resource defined\n");
214		ret = -ENXIO;
215		goto out;
216	}
217
218	irq = platform_get_irq(pdev, 0);
219	if (irq <= 0) {
220		dev_dbg(&pdev->dev, "could not get irq\n");
221		ret = -ENXIO;
222		goto out;
223	}
224
225	rtc->irq = irq;
226	rtc->regs = ioremap(regs->start, resource_size(regs));
227	if (!rtc->regs) {
228		ret = -ENOMEM;
229		dev_dbg(&pdev->dev, "could not map I/O memory\n");
230		goto out;
231	}
232	spin_lock_init(&rtc->lock);
233
234	/*
235	 * Maybe init RTC: count from zero at 1 Hz, disable wrap irq.
236	 *
237	 * Do not reset VAL register, as it can hold an old time
238	 * from last JTAG reset.
239	 */
240	if (!(rtc_readl(rtc, CTRL) & RTC_BIT(CTRL_EN))) {
241		rtc_writel(rtc, CTRL, RTC_BIT(CTRL_PCLR));
242		rtc_writel(rtc, IDR, RTC_BIT(IDR_TOPI));
243		rtc_writel(rtc, CTRL, RTC_BF(CTRL_PSEL, 0xe)
244				| RTC_BIT(CTRL_EN));
245	}
246
247	ret = request_irq(irq, at32_rtc_interrupt, IRQF_SHARED, "rtc", rtc);
248	if (ret) {
249		dev_dbg(&pdev->dev, "could not request irq %d\n", irq);
250		goto out_iounmap;
251	}
252
253	platform_set_drvdata(pdev, rtc);
254
255	rtc->rtc = rtc_device_register(pdev->name, &pdev->dev,
256				&at32_rtc_ops, THIS_MODULE);
257	if (IS_ERR(rtc->rtc)) {
258		dev_dbg(&pdev->dev, "could not register rtc device\n");
259		ret = PTR_ERR(rtc->rtc);
260		goto out_free_irq;
261	}
262
263	device_init_wakeup(&pdev->dev, 1);
264
265	dev_info(&pdev->dev, "Atmel RTC for AT32AP700x at %08lx irq %ld\n",
266			(unsigned long)rtc->regs, rtc->irq);
267
268	return 0;
269
270out_free_irq:
271	platform_set_drvdata(pdev, NULL);
272	free_irq(irq, rtc);
273out_iounmap:
274	iounmap(rtc->regs);
275out:
276	kfree(rtc);
277	return ret;
278}
279
280static int __exit at32_rtc_remove(struct platform_device *pdev)
281{
282	struct rtc_at32ap700x *rtc = platform_get_drvdata(pdev);
283
284	device_init_wakeup(&pdev->dev, 0);
285
286	free_irq(rtc->irq, rtc);
287	iounmap(rtc->regs);
288	rtc_device_unregister(rtc->rtc);
289	kfree(rtc);
290	platform_set_drvdata(pdev, NULL);
291
292	return 0;
293}
294
295MODULE_ALIAS("platform:at32ap700x_rtc");
296
297static struct platform_driver at32_rtc_driver = {
298	.remove		= __exit_p(at32_rtc_remove),
299	.driver		= {
300		.name	= "at32ap700x_rtc",
301		.owner	= THIS_MODULE,
302	},
303};
304
305static int __init at32_rtc_init(void)
306{
307	return platform_driver_probe(&at32_rtc_driver, at32_rtc_probe);
308}
309module_init(at32_rtc_init);
310
311static void __exit at32_rtc_exit(void)
312{
313	platform_driver_unregister(&at32_rtc_driver);
314}
315module_exit(at32_rtc_exit);
316
317MODULE_AUTHOR("Hans-Christian Egtvedt <hcegtvedt@atmel.com>");
318MODULE_DESCRIPTION("Real time clock for AVR32 AT32AP700x");
319MODULE_LICENSE("GPL");