1/*
  2 * Copyright (C) 2007-2009 ST-Ericsson AB
  3 * License terms: GNU General Public License (GPL) version 2
  4 * Real Time Clock interface for ST-Ericsson AB COH 901 331 RTC.
  5 * Author: Linus Walleij <linus.walleij@stericsson.com>
  6 * Based on rtc-pl031.c by Deepak Saxena <dsaxena@plexity.net>
  7 * Copyright 2006 (c) MontaVista Software, Inc.
  8 */
  9#include <linux/init.h>
 10#include <linux/module.h>
 11#include <linux/rtc.h>
 12#include <linux/clk.h>
 13#include <linux/interrupt.h>
 14#include <linux/pm.h>
 15#include <linux/platform_device.h>
 16#include <linux/io.h>
 17#include <linux/slab.h>
 18
 19/*
 20 * Registers in the COH 901 331
 21 */
 22/* Alarm value 32bit (R/W) */
 23#define COH901331_ALARM		0x00U
 24/* Used to set current time 32bit (R/W) */
 25#define COH901331_SET_TIME	0x04U
 26/* Indication if current time is valid 32bit (R/-) */
 27#define COH901331_VALID		0x08U
 28/* Read the current time 32bit (R/-) */
 29#define COH901331_CUR_TIME	0x0cU
 30/* Event register for the "alarm" interrupt */
 31#define COH901331_IRQ_EVENT	0x10U
 32/* Mask register for the "alarm" interrupt */
 33#define COH901331_IRQ_MASK	0x14U
 34/* Force register for the "alarm" interrupt */
 35#define COH901331_IRQ_FORCE	0x18U
 36
 37/*
 38 * Reference to RTC block clock
 39 * Notice that the frequent clk_enable()/clk_disable() on this
 40 * clock is mainly to be able to turn on/off other clocks in the
 41 * hierarchy as needed, the RTC clock is always on anyway.
 42 */
 43struct coh901331_port {
 44	struct rtc_device *rtc;
 45	struct clk *clk;
 46	void __iomem *virtbase;
 47	int irq;
 48#ifdef CONFIG_PM_SLEEP
 49	u32 irqmaskstore;
 50#endif
 51};
 52
 53static irqreturn_t coh901331_interrupt(int irq, void *data)
 54{
 55	struct coh901331_port *rtap = data;
 56
 57	clk_enable(rtap->clk);
 58	/* Ack IRQ */
 59	writel(1, rtap->virtbase + COH901331_IRQ_EVENT);
 60	/*
 61	 * Disable the interrupt. This is necessary because
 62	 * the RTC lives on a lower-clocked line and will
 63	 * not release the IRQ line until after a few (slower)
 64	 * clock cycles. The interrupt will be re-enabled when
 65	 * a new alarm is set anyway.
 66	 */
 67	writel(0, rtap->virtbase + COH901331_IRQ_MASK);
 68	clk_disable(rtap->clk);
 69
 70	/* Set alarm flag */
 71	rtc_update_irq(rtap->rtc, 1, RTC_AF);
 72
 73	return IRQ_HANDLED;
 74}
 75
 76static int coh901331_read_time(struct device *dev, struct rtc_time *tm)
 77{
 78	struct coh901331_port *rtap = dev_get_drvdata(dev);
 79
 80	clk_enable(rtap->clk);
 81	/* Check if the time is valid */
 82	if (readl(rtap->virtbase + COH901331_VALID)) {
 83		rtc_time_to_tm(readl(rtap->virtbase + COH901331_CUR_TIME), tm);
 84		clk_disable(rtap->clk);
 85		return rtc_valid_tm(tm);
 86	}
 87	clk_disable(rtap->clk);
 88	return -EINVAL;
 89}
 90
 91static int coh901331_set_mmss(struct device *dev, unsigned long secs)
 92{
 93	struct coh901331_port *rtap = dev_get_drvdata(dev);
 94
 95	clk_enable(rtap->clk);
 96	writel(secs, rtap->virtbase + COH901331_SET_TIME);
 97	clk_disable(rtap->clk);
 98
 99	return 0;
100}
101
102static int coh901331_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
103{
104	struct coh901331_port *rtap = dev_get_drvdata(dev);
105
106	clk_enable(rtap->clk);
107	rtc_time_to_tm(readl(rtap->virtbase + COH901331_ALARM), &alarm->time);
108	alarm->pending = readl(rtap->virtbase + COH901331_IRQ_EVENT) & 1U;
109	alarm->enabled = readl(rtap->virtbase + COH901331_IRQ_MASK) & 1U;
110	clk_disable(rtap->clk);
111
112	return 0;
113}
114
115static int coh901331_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
116{
117	struct coh901331_port *rtap = dev_get_drvdata(dev);
118	unsigned long time;
119
120	rtc_tm_to_time(&alarm->time, &time);
121	clk_enable(rtap->clk);
122	writel(time, rtap->virtbase + COH901331_ALARM);
123	writel(alarm->enabled, rtap->virtbase + COH901331_IRQ_MASK);
124	clk_disable(rtap->clk);
125
126	return 0;
127}
128
129static int coh901331_alarm_irq_enable(struct device *dev, unsigned int enabled)
130{
131	struct coh901331_port *rtap = dev_get_drvdata(dev);
132
133	clk_enable(rtap->clk);
134	if (enabled)
135		writel(1, rtap->virtbase + COH901331_IRQ_MASK);
136	else
137		writel(0, rtap->virtbase + COH901331_IRQ_MASK);
138	clk_disable(rtap->clk);
139
140	return 0;
141}
142
143static struct rtc_class_ops coh901331_ops = {
144	.read_time = coh901331_read_time,
145	.set_mmss = coh901331_set_mmss,
146	.read_alarm = coh901331_read_alarm,
147	.set_alarm = coh901331_set_alarm,
148	.alarm_irq_enable = coh901331_alarm_irq_enable,
149};
150
151static int __exit coh901331_remove(struct platform_device *pdev)
152{
153	struct coh901331_port *rtap = platform_get_drvdata(pdev);
154
155	if (rtap)
156		clk_unprepare(rtap->clk);
157
158	return 0;
159}
160
161
162static int __init coh901331_probe(struct platform_device *pdev)
163{
164	int ret;
165	struct coh901331_port *rtap;
166	struct resource *res;
167
168	rtap = devm_kzalloc(&pdev->dev,
169			    sizeof(struct coh901331_port), GFP_KERNEL);
170	if (!rtap)
171		return -ENOMEM;
172
173	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
174	rtap->virtbase  = devm_ioremap_resource(&pdev->dev, res);
175	if (IS_ERR(rtap->virtbase))
176		return PTR_ERR(rtap->virtbase);
177
178	rtap->irq = platform_get_irq(pdev, 0);
179	if (devm_request_irq(&pdev->dev, rtap->irq, coh901331_interrupt, 0,
180			     "RTC COH 901 331 Alarm", rtap))
181		return -EIO;
182
183	rtap->clk = devm_clk_get(&pdev->dev, NULL);
184	if (IS_ERR(rtap->clk)) {
185		ret = PTR_ERR(rtap->clk);
186		dev_err(&pdev->dev, "could not get clock\n");
187		return ret;
188	}
189
190	/* We enable/disable the clock only to assure it works */
191	ret = clk_prepare_enable(rtap->clk);
192	if (ret) {
193		dev_err(&pdev->dev, "could not enable clock\n");
194		return ret;
195	}
196	clk_disable(rtap->clk);
197
198	platform_set_drvdata(pdev, rtap);
199	rtap->rtc = devm_rtc_device_register(&pdev->dev, "coh901331",
200					&coh901331_ops, THIS_MODULE);
201	if (IS_ERR(rtap->rtc)) {
202		ret = PTR_ERR(rtap->rtc);
203		goto out_no_rtc;
204	}
205
206	return 0;
207
208 out_no_rtc:
209	clk_unprepare(rtap->clk);
210	return ret;
211}
212
213#ifdef CONFIG_PM_SLEEP
214static int coh901331_suspend(struct device *dev)
215{
216	struct coh901331_port *rtap = dev_get_drvdata(dev);
217
218	/*
219	 * If this RTC alarm will be used for waking the system up,
220	 * don't disable it of course. Else we just disable the alarm
221	 * and await suspension.
222	 */
223	if (device_may_wakeup(dev)) {
224		enable_irq_wake(rtap->irq);
225	} else {
226		clk_enable(rtap->clk);
227		rtap->irqmaskstore = readl(rtap->virtbase + COH901331_IRQ_MASK);
228		writel(0, rtap->virtbase + COH901331_IRQ_MASK);
229		clk_disable(rtap->clk);
230	}
231	clk_unprepare(rtap->clk);
232	return 0;
233}
234
235static int coh901331_resume(struct device *dev)
236{
237	struct coh901331_port *rtap = dev_get_drvdata(dev);
238
239	clk_prepare(rtap->clk);
240	if (device_may_wakeup(dev)) {
241		disable_irq_wake(rtap->irq);
242	} else {
243		clk_enable(rtap->clk);
244		writel(rtap->irqmaskstore, rtap->virtbase + COH901331_IRQ_MASK);
245		clk_disable(rtap->clk);
246	}
247	return 0;
248}
249#endif
250
251static SIMPLE_DEV_PM_OPS(coh901331_pm_ops, coh901331_suspend, coh901331_resume);
252
253static void coh901331_shutdown(struct platform_device *pdev)
254{
255	struct coh901331_port *rtap = platform_get_drvdata(pdev);
256
257	clk_enable(rtap->clk);
258	writel(0, rtap->virtbase + COH901331_IRQ_MASK);
259	clk_disable_unprepare(rtap->clk);
260}
261
262static const struct of_device_id coh901331_dt_match[] = {
263	{ .compatible = "stericsson,coh901331" },
264	{},
265};
266MODULE_DEVICE_TABLE(of, coh901331_dt_match);
267
268static struct platform_driver coh901331_driver = {
269	.driver = {
270		.name = "rtc-coh901331",
271		.pm = &coh901331_pm_ops,
272		.of_match_table = coh901331_dt_match,
273	},
274	.remove = __exit_p(coh901331_remove),
275	.shutdown = coh901331_shutdown,
276};
277
278module_platform_driver_probe(coh901331_driver, coh901331_probe);
279
280MODULE_AUTHOR("Linus Walleij <linus.walleij@stericsson.com>");
281MODULE_DESCRIPTION("ST-Ericsson AB COH 901 331 RTC Driver");
282MODULE_LICENSE("GPL");