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Linux/drivers/rtc/rtc-at32ap700x.c

  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 
 61 struct 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 
 70 static 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 
 81 static 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 
 94 static 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 
107 static 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 
137 static 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         }
159 out:
160         spin_unlock_irq(&rtc->lock);
161 
162         return ret;
163 }
164 
165 static 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 
190 static 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 
198 static 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 
267 static int __exit at32_rtc_remove(struct platform_device *pdev)
268 {
269         device_init_wakeup(&pdev->dev, 0);
270 
271         return 0;
272 }
273 
274 MODULE_ALIAS("platform:at32ap700x_rtc");
275 
276 static struct platform_driver at32_rtc_driver = {
277         .remove         = __exit_p(at32_rtc_remove),
278         .driver         = {
279                 .name   = "at32ap700x_rtc",
280                 .owner  = THIS_MODULE,
281         },
282 };
283 
284 module_platform_driver_probe(at32_rtc_driver, at32_rtc_probe);
285 
286 MODULE_AUTHOR("Hans-Christian Egtvedt <hcegtvedt@atmel.com>");
287 MODULE_DESCRIPTION("Real time clock for AVR32 AT32AP700x");
288 MODULE_LICENSE("GPL");
289 

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