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
coh901331_interrupt(int irq,void * data)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
coh901331_read_time(struct device * dev,struct rtc_time * tm)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
coh901331_set_mmss(struct device * dev,unsigned long secs)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
coh901331_read_alarm(struct device * dev,struct rtc_wkalrm * alarm)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
coh901331_set_alarm(struct device * dev,struct rtc_wkalrm * alarm)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
coh901331_alarm_irq_enable(struct device * dev,unsigned int enabled)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 const 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
coh901331_remove(struct platform_device * pdev)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
coh901331_probe(struct platform_device * pdev)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
coh901331_suspend(struct device * dev)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
coh901331_resume(struct device * dev)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
coh901331_shutdown(struct platform_device * pdev)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 MODULE_DEVICE_TABLE(of, coh901331_dt_match);
267
268 static 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
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