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/mod_devicetable.h>
12 #include <linux/rtc.h>
13 #include <linux/clk.h>
14 #include <linux/interrupt.h>
15 #include <linux/pm.h>
16 #include <linux/platform_device.h>
17 #include <linux/io.h>
18 #include <linux/slab.h>
19
20 /*
21 * Registers in the COH 901 331
22 */
23 /* Alarm value 32bit (R/W) */
24 #define COH901331_ALARM 0x00U
25 /* Used to set current time 32bit (R/W) */
26 #define COH901331_SET_TIME 0x04U
27 /* Indication if current time is valid 32bit (R/-) */
28 #define COH901331_VALID 0x08U
29 /* Read the current time 32bit (R/-) */
30 #define COH901331_CUR_TIME 0x0cU
31 /* Event register for the "alarm" interrupt */
32 #define COH901331_IRQ_EVENT 0x10U
33 /* Mask register for the "alarm" interrupt */
34 #define COH901331_IRQ_MASK 0x14U
35 /* Force register for the "alarm" interrupt */
36 #define COH901331_IRQ_FORCE 0x18U
37
38 /*
39 * Reference to RTC block clock
40 * Notice that the frequent clk_enable()/clk_disable() on this
41 * clock is mainly to be able to turn on/off other clocks in the
42 * hierarchy as needed, the RTC clock is always on anyway.
43 */
44 struct coh901331_port {
45 struct rtc_device *rtc;
46 struct clk *clk;
47 void __iomem *virtbase;
48 int irq;
49 #ifdef CONFIG_PM_SLEEP
50 u32 irqmaskstore;
51 #endif
52 };
53
coh901331_interrupt(int irq,void * data)54 static irqreturn_t coh901331_interrupt(int irq, void *data)
55 {
56 struct coh901331_port *rtap = data;
57
58 clk_enable(rtap->clk);
59 /* Ack IRQ */
60 writel(1, rtap->virtbase + COH901331_IRQ_EVENT);
61 /*
62 * Disable the interrupt. This is necessary because
63 * the RTC lives on a lower-clocked line and will
64 * not release the IRQ line until after a few (slower)
65 * clock cycles. The interrupt will be re-enabled when
66 * a new alarm is set anyway.
67 */
68 writel(0, rtap->virtbase + COH901331_IRQ_MASK);
69 clk_disable(rtap->clk);
70
71 /* Set alarm flag */
72 rtc_update_irq(rtap->rtc, 1, RTC_AF);
73
74 return IRQ_HANDLED;
75 }
76
coh901331_read_time(struct device * dev,struct rtc_time * tm)77 static int coh901331_read_time(struct device *dev, struct rtc_time *tm)
78 {
79 struct coh901331_port *rtap = dev_get_drvdata(dev);
80
81 clk_enable(rtap->clk);
82 /* Check if the time is valid */
83 if (readl(rtap->virtbase + COH901331_VALID)) {
84 rtc_time_to_tm(readl(rtap->virtbase + COH901331_CUR_TIME), tm);
85 clk_disable(rtap->clk);
86 return 0;
87 }
88 clk_disable(rtap->clk);
89 return -EINVAL;
90 }
91
coh901331_set_mmss(struct device * dev,unsigned long secs)92 static int coh901331_set_mmss(struct device *dev, unsigned long secs)
93 {
94 struct coh901331_port *rtap = dev_get_drvdata(dev);
95
96 clk_enable(rtap->clk);
97 writel(secs, rtap->virtbase + COH901331_SET_TIME);
98 clk_disable(rtap->clk);
99
100 return 0;
101 }
102
coh901331_read_alarm(struct device * dev,struct rtc_wkalrm * alarm)103 static int coh901331_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
104 {
105 struct coh901331_port *rtap = dev_get_drvdata(dev);
106
107 clk_enable(rtap->clk);
108 rtc_time_to_tm(readl(rtap->virtbase + COH901331_ALARM), &alarm->time);
109 alarm->pending = readl(rtap->virtbase + COH901331_IRQ_EVENT) & 1U;
110 alarm->enabled = readl(rtap->virtbase + COH901331_IRQ_MASK) & 1U;
111 clk_disable(rtap->clk);
112
113 return 0;
114 }
115
coh901331_set_alarm(struct device * dev,struct rtc_wkalrm * alarm)116 static int coh901331_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
117 {
118 struct coh901331_port *rtap = dev_get_drvdata(dev);
119 unsigned long time;
120
121 rtc_tm_to_time(&alarm->time, &time);
122 clk_enable(rtap->clk);
123 writel(time, rtap->virtbase + COH901331_ALARM);
124 writel(alarm->enabled, rtap->virtbase + COH901331_IRQ_MASK);
125 clk_disable(rtap->clk);
126
127 return 0;
128 }
129
coh901331_alarm_irq_enable(struct device * dev,unsigned int enabled)130 static int coh901331_alarm_irq_enable(struct device *dev, unsigned int enabled)
131 {
132 struct coh901331_port *rtap = dev_get_drvdata(dev);
133
134 clk_enable(rtap->clk);
135 if (enabled)
136 writel(1, rtap->virtbase + COH901331_IRQ_MASK);
137 else
138 writel(0, rtap->virtbase + COH901331_IRQ_MASK);
139 clk_disable(rtap->clk);
140
141 return 0;
142 }
143
144 static const struct rtc_class_ops coh901331_ops = {
145 .read_time = coh901331_read_time,
146 .set_mmss = coh901331_set_mmss,
147 .read_alarm = coh901331_read_alarm,
148 .set_alarm = coh901331_set_alarm,
149 .alarm_irq_enable = coh901331_alarm_irq_enable,
150 };
151
coh901331_remove(struct platform_device * pdev)152 static int __exit coh901331_remove(struct platform_device *pdev)
153 {
154 struct coh901331_port *rtap = platform_get_drvdata(pdev);
155
156 if (rtap)
157 clk_unprepare(rtap->clk);
158
159 return 0;
160 }
161
162
coh901331_probe(struct platform_device * pdev)163 static int __init coh901331_probe(struct platform_device *pdev)
164 {
165 int ret;
166 struct coh901331_port *rtap;
167 struct resource *res;
168
169 rtap = devm_kzalloc(&pdev->dev,
170 sizeof(struct coh901331_port), GFP_KERNEL);
171 if (!rtap)
172 return -ENOMEM;
173
174 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
175 rtap->virtbase = devm_ioremap_resource(&pdev->dev, res);
176 if (IS_ERR(rtap->virtbase))
177 return PTR_ERR(rtap->virtbase);
178
179 rtap->irq = platform_get_irq(pdev, 0);
180 if (devm_request_irq(&pdev->dev, rtap->irq, coh901331_interrupt, 0,
181 "RTC COH 901 331 Alarm", rtap))
182 return -EIO;
183
184 rtap->clk = devm_clk_get(&pdev->dev, NULL);
185 if (IS_ERR(rtap->clk)) {
186 ret = PTR_ERR(rtap->clk);
187 dev_err(&pdev->dev, "could not get clock\n");
188 return ret;
189 }
190
191 /* We enable/disable the clock only to assure it works */
192 ret = clk_prepare_enable(rtap->clk);
193 if (ret) {
194 dev_err(&pdev->dev, "could not enable clock\n");
195 return ret;
196 }
197 clk_disable(rtap->clk);
198
199 platform_set_drvdata(pdev, rtap);
200 rtap->rtc = devm_rtc_device_register(&pdev->dev, "coh901331",
201 &coh901331_ops, THIS_MODULE);
202 if (IS_ERR(rtap->rtc)) {
203 ret = PTR_ERR(rtap->rtc);
204 goto out_no_rtc;
205 }
206
207 return 0;
208
209 out_no_rtc:
210 clk_unprepare(rtap->clk);
211 return ret;
212 }
213
214 #ifdef CONFIG_PM_SLEEP
coh901331_suspend(struct device * dev)215 static int coh901331_suspend(struct device *dev)
216 {
217 struct coh901331_port *rtap = dev_get_drvdata(dev);
218
219 /*
220 * If this RTC alarm will be used for waking the system up,
221 * don't disable it of course. Else we just disable the alarm
222 * and await suspension.
223 */
224 if (device_may_wakeup(dev)) {
225 enable_irq_wake(rtap->irq);
226 } else {
227 clk_enable(rtap->clk);
228 rtap->irqmaskstore = readl(rtap->virtbase + COH901331_IRQ_MASK);
229 writel(0, rtap->virtbase + COH901331_IRQ_MASK);
230 clk_disable(rtap->clk);
231 }
232 clk_unprepare(rtap->clk);
233 return 0;
234 }
235
coh901331_resume(struct device * dev)236 static int coh901331_resume(struct device *dev)
237 {
238 struct coh901331_port *rtap = dev_get_drvdata(dev);
239
240 clk_prepare(rtap->clk);
241 if (device_may_wakeup(dev)) {
242 disable_irq_wake(rtap->irq);
243 } else {
244 clk_enable(rtap->clk);
245 writel(rtap->irqmaskstore, rtap->virtbase + COH901331_IRQ_MASK);
246 clk_disable(rtap->clk);
247 }
248 return 0;
249 }
250 #endif
251
252 static SIMPLE_DEV_PM_OPS(coh901331_pm_ops, coh901331_suspend, coh901331_resume);
253
coh901331_shutdown(struct platform_device * pdev)254 static void coh901331_shutdown(struct platform_device *pdev)
255 {
256 struct coh901331_port *rtap = platform_get_drvdata(pdev);
257
258 clk_enable(rtap->clk);
259 writel(0, rtap->virtbase + COH901331_IRQ_MASK);
260 clk_disable_unprepare(rtap->clk);
261 }
262
263 static const struct of_device_id coh901331_dt_match[] = {
264 { .compatible = "stericsson,coh901331" },
265 {},
266 };
267 MODULE_DEVICE_TABLE(of, coh901331_dt_match);
268
269 static struct platform_driver coh901331_driver = {
270 .driver = {
271 .name = "rtc-coh901331",
272 .pm = &coh901331_pm_ops,
273 .of_match_table = coh901331_dt_match,
274 },
275 .remove = __exit_p(coh901331_remove),
276 .shutdown = coh901331_shutdown,
277 };
278
279 module_platform_driver_probe(coh901331_driver, coh901331_probe);
280
281 MODULE_AUTHOR("Linus Walleij <linus.walleij@stericsson.com>");
282 MODULE_DESCRIPTION("ST-Ericsson AB COH 901 331 RTC Driver");
283 MODULE_LICENSE("GPL");
284