Root/drivers/rtc/rtc-coh901331.c

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    u32 phybase;
47    u32 physize;
48    void __iomem *virtbase;
49    int irq;
50#ifdef CONFIG_PM
51    u32 irqmaskstore;
52#endif
53};
54
55static irqreturn_t coh901331_interrupt(int irq, void *data)
56{
57    struct coh901331_port *rtap = data;
58
59    clk_enable(rtap->clk);
60    /* Ack IRQ */
61    writel(1, rtap->virtbase + COH901331_IRQ_EVENT);
62    /*
63     * Disable the interrupt. This is necessary because
64     * the RTC lives on a lower-clocked line and will
65     * not release the IRQ line until after a few (slower)
66     * clock cycles. The interrupt will be re-enabled when
67     * a new alarm is set anyway.
68     */
69    writel(0, rtap->virtbase + COH901331_IRQ_MASK);
70    clk_disable(rtap->clk);
71
72    /* Set alarm flag */
73    rtc_update_irq(rtap->rtc, 1, RTC_AF);
74
75    return IRQ_HANDLED;
76}
77
78static int coh901331_read_time(struct device *dev, struct rtc_time *tm)
79{
80    struct coh901331_port *rtap = dev_get_drvdata(dev);
81
82    clk_enable(rtap->clk);
83    /* Check if the time is valid */
84    if (readl(rtap->virtbase + COH901331_VALID)) {
85        rtc_time_to_tm(readl(rtap->virtbase + COH901331_CUR_TIME), tm);
86        clk_disable(rtap->clk);
87        return rtc_valid_tm(tm);
88    }
89    clk_disable(rtap->clk);
90    return -EINVAL;
91}
92
93static int coh901331_set_mmss(struct device *dev, unsigned long secs)
94{
95    struct coh901331_port *rtap = dev_get_drvdata(dev);
96
97    clk_enable(rtap->clk);
98    writel(secs, rtap->virtbase + COH901331_SET_TIME);
99    clk_disable(rtap->clk);
100
101    return 0;
102}
103
104static int coh901331_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
105{
106    struct coh901331_port *rtap = dev_get_drvdata(dev);
107
108    clk_enable(rtap->clk);
109    rtc_time_to_tm(readl(rtap->virtbase + COH901331_ALARM), &alarm->time);
110    alarm->pending = readl(rtap->virtbase + COH901331_IRQ_EVENT) & 1U;
111    alarm->enabled = readl(rtap->virtbase + COH901331_IRQ_MASK) & 1U;
112    clk_disable(rtap->clk);
113
114    return 0;
115}
116
117static int coh901331_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
118{
119    struct coh901331_port *rtap = dev_get_drvdata(dev);
120    unsigned long time;
121
122    rtc_tm_to_time(&alarm->time, &time);
123    clk_enable(rtap->clk);
124    writel(time, rtap->virtbase + COH901331_ALARM);
125    writel(alarm->enabled, rtap->virtbase + COH901331_IRQ_MASK);
126    clk_disable(rtap->clk);
127
128    return 0;
129}
130
131static int coh901331_alarm_irq_enable(struct device *dev, unsigned int enabled)
132{
133    struct coh901331_port *rtap = dev_get_drvdata(dev);
134
135    clk_enable(rtap->clk);
136    if (enabled)
137        writel(1, rtap->virtbase + COH901331_IRQ_MASK);
138    else
139        writel(0, rtap->virtbase + COH901331_IRQ_MASK);
140    clk_disable(rtap->clk);
141
142    return 0;
143}
144
145static struct rtc_class_ops coh901331_ops = {
146    .read_time = coh901331_read_time,
147    .set_mmss = coh901331_set_mmss,
148    .read_alarm = coh901331_read_alarm,
149    .set_alarm = coh901331_set_alarm,
150    .alarm_irq_enable = coh901331_alarm_irq_enable,
151};
152
153static int __exit coh901331_remove(struct platform_device *pdev)
154{
155    struct coh901331_port *rtap = dev_get_drvdata(&pdev->dev);
156
157    if (rtap) {
158        rtc_device_unregister(rtap->rtc);
159        clk_unprepare(rtap->clk);
160        clk_put(rtap->clk);
161        platform_set_drvdata(pdev, NULL);
162    }
163
164    return 0;
165}
166
167
168static int __init coh901331_probe(struct platform_device *pdev)
169{
170    int ret;
171    struct coh901331_port *rtap;
172    struct resource *res;
173
174    rtap = devm_kzalloc(&pdev->dev,
175                sizeof(struct coh901331_port), GFP_KERNEL);
176    if (!rtap)
177        return -ENOMEM;
178
179    res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
180    if (!res)
181        return -ENOENT;
182
183    rtap->phybase = res->start;
184    rtap->physize = resource_size(res);
185
186    if (devm_request_mem_region(&pdev->dev, rtap->phybase, rtap->physize,
187                    "rtc-coh901331") == NULL)
188        return -EBUSY;
189
190    rtap->virtbase = devm_ioremap(&pdev->dev, rtap->phybase, rtap->physize);
191    if (!rtap->virtbase)
192        return -ENOMEM;
193
194    rtap->irq = platform_get_irq(pdev, 0);
195    if (devm_request_irq(&pdev->dev, rtap->irq, coh901331_interrupt, 0,
196                 "RTC COH 901 331 Alarm", rtap))
197        return -EIO;
198
199    rtap->clk = clk_get(&pdev->dev, NULL);
200    if (IS_ERR(rtap->clk)) {
201        ret = PTR_ERR(rtap->clk);
202        dev_err(&pdev->dev, "could not get clock\n");
203        return ret;
204    }
205
206    /* We enable/disable the clock only to assure it works */
207    ret = clk_prepare_enable(rtap->clk);
208    if (ret) {
209        dev_err(&pdev->dev, "could not enable clock\n");
210        goto out_no_clk_prepenable;
211    }
212    clk_disable(rtap->clk);
213
214    platform_set_drvdata(pdev, rtap);
215    rtap->rtc = rtc_device_register("coh901331", &pdev->dev, &coh901331_ops,
216                     THIS_MODULE);
217    if (IS_ERR(rtap->rtc)) {
218        ret = PTR_ERR(rtap->rtc);
219        goto out_no_rtc;
220    }
221
222    return 0;
223
224 out_no_rtc:
225    platform_set_drvdata(pdev, NULL);
226    clk_unprepare(rtap->clk);
227 out_no_clk_prepenable:
228    clk_put(rtap->clk);
229    return ret;
230}
231
232#ifdef CONFIG_PM
233static int coh901331_suspend(struct platform_device *pdev, pm_message_t state)
234{
235    struct coh901331_port *rtap = dev_get_drvdata(&pdev->dev);
236
237    /*
238     * If this RTC alarm will be used for waking the system up,
239     * don't disable it of course. Else we just disable the alarm
240     * and await suspension.
241     */
242    if (device_may_wakeup(&pdev->dev)) {
243        enable_irq_wake(rtap->irq);
244    } else {
245        clk_enable(rtap->clk);
246        rtap->irqmaskstore = readl(rtap->virtbase + COH901331_IRQ_MASK);
247        writel(0, rtap->virtbase + COH901331_IRQ_MASK);
248        clk_disable(rtap->clk);
249    }
250    clk_unprepare(rtap->clk);
251    return 0;
252}
253
254static int coh901331_resume(struct platform_device *pdev)
255{
256    struct coh901331_port *rtap = dev_get_drvdata(&pdev->dev);
257
258    clk_prepare(rtap->clk);
259    if (device_may_wakeup(&pdev->dev)) {
260        disable_irq_wake(rtap->irq);
261    } else {
262        clk_enable(rtap->clk);
263        writel(rtap->irqmaskstore, rtap->virtbase + COH901331_IRQ_MASK);
264        clk_disable(rtap->clk);
265    }
266    return 0;
267}
268#else
269#define coh901331_suspend NULL
270#define coh901331_resume NULL
271#endif
272
273static void coh901331_shutdown(struct platform_device *pdev)
274{
275    struct coh901331_port *rtap = dev_get_drvdata(&pdev->dev);
276
277    clk_enable(rtap->clk);
278    writel(0, rtap->virtbase + COH901331_IRQ_MASK);
279    clk_disable(rtap->clk);
280    clk_unprepare(rtap->clk);
281}
282
283static struct platform_driver coh901331_driver = {
284    .driver = {
285        .name = "rtc-coh901331",
286        .owner = THIS_MODULE,
287    },
288    .remove = __exit_p(coh901331_remove),
289    .suspend = coh901331_suspend,
290    .resume = coh901331_resume,
291    .shutdown = coh901331_shutdown,
292};
293
294static int __init coh901331_init(void)
295{
296    return platform_driver_probe(&coh901331_driver, coh901331_probe);
297}
298
299static void __exit coh901331_exit(void)
300{
301    platform_driver_unregister(&coh901331_driver);
302}
303
304module_init(coh901331_init);
305module_exit(coh901331_exit);
306
307MODULE_AUTHOR("Linus Walleij <linus.walleij@stericsson.com>");
308MODULE_DESCRIPTION("ST-Ericsson AB COH 901 331 RTC Driver");
309MODULE_LICENSE("GPL");
310

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