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
at32_rtc_readtime(struct device * dev,struct rtc_time * tm)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
at32_rtc_settime(struct device * dev,struct rtc_time * tm)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
at32_rtc_readalarm(struct device * dev,struct rtc_wkalrm * alrm)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
at32_rtc_setalarm(struct device * dev,struct rtc_wkalrm * alrm)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
at32_rtc_alarm_irq_enable(struct device * dev,unsigned int enabled)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
at32_rtc_interrupt(int irq,void * dev_id)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
at32_rtc_probe(struct platform_device * pdev)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
at32_rtc_remove(struct platform_device * pdev)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 },
281 };
282
283 module_platform_driver_probe(at32_rtc_driver, at32_rtc_probe);
284
285 MODULE_AUTHOR("Hans-Christian Egtvedt <egtvedt@samfundet.no>");
286 MODULE_DESCRIPTION("Real time clock for AVR32 AT32AP700x");
287 MODULE_LICENSE("GPL");
288