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Linux/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  */
 43 struct 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 
 53 static 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 
 76 static 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 
 91 static 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 
102 static 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 
115 static 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 
129 static 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 
143 static 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 
151 static 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 
162 static 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
214 static 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 
235 static 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 
251 static SIMPLE_DEV_PM_OPS(coh901331_pm_ops, coh901331_suspend, coh901331_resume);
252 
253 static 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 
262 static const struct of_device_id coh901331_dt_match[] = {
263         { .compatible = "stericsson,coh901331" },
264         {},
265 };
266 
267 static struct platform_driver coh901331_driver = {
268         .driver = {
269                 .name = "rtc-coh901331",
270                 .owner = THIS_MODULE,
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 
278 module_platform_driver_probe(coh901331_driver, coh901331_probe);
279 
280 MODULE_AUTHOR("Linus Walleij <linus.walleij@stericsson.com>");
281 MODULE_DESCRIPTION("ST-Ericsson AB COH 901 331 RTC Driver");
282 MODULE_LICENSE("GPL");
283 

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