1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright (C) 2007-2009 ST-Ericsson AB
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 clk_disable(rtap->clk);
85 return -EINVAL;
86 }
87
88 rtc_time64_to_tm(readl(rtap->virtbase + COH901331_CUR_TIME), tm);
89 clk_disable(rtap->clk);
90 return 0;
91 }
92
coh901331_set_time(struct device * dev,struct rtc_time * tm)93 static int coh901331_set_time(struct device *dev, struct rtc_time *tm)
94 {
95 struct coh901331_port *rtap = dev_get_drvdata(dev);
96
97 clk_enable(rtap->clk);
98 writel(rtc_tm_to_time64(tm), rtap->virtbase + COH901331_SET_TIME);
99 clk_disable(rtap->clk);
100
101 return 0;
102 }
103
coh901331_read_alarm(struct device * dev,struct rtc_wkalrm * alarm)104 static int coh901331_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
105 {
106 struct coh901331_port *rtap = dev_get_drvdata(dev);
107
108 clk_enable(rtap->clk);
109 rtc_time64_to_tm(readl(rtap->virtbase + COH901331_ALARM), &alarm->time);
110 alarm->pending = readl(rtap->virtbase + COH901331_IRQ_EVENT) & 1U;
111 alarm->enabled = readl(rtap->virtbase + COH901331_IRQ_MASK) & 1U;
112 clk_disable(rtap->clk);
113
114 return 0;
115 }
116
coh901331_set_alarm(struct device * dev,struct rtc_wkalrm * alarm)117 static int coh901331_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
118 {
119 struct coh901331_port *rtap = dev_get_drvdata(dev);
120 unsigned long time = rtc_tm_to_time64(&alarm->time);
121
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_time = coh901331_set_time,
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
168 rtap = devm_kzalloc(&pdev->dev,
169 sizeof(struct coh901331_port), GFP_KERNEL);
170 if (!rtap)
171 return -ENOMEM;
172
173 rtap->virtbase = devm_platform_ioremap_resource(pdev, 0);
174 if (IS_ERR(rtap->virtbase))
175 return PTR_ERR(rtap->virtbase);
176
177 rtap->irq = platform_get_irq(pdev, 0);
178 if (devm_request_irq(&pdev->dev, rtap->irq, coh901331_interrupt, 0,
179 "RTC COH 901 331 Alarm", rtap))
180 return -EIO;
181
182 rtap->clk = devm_clk_get(&pdev->dev, NULL);
183 if (IS_ERR(rtap->clk)) {
184 ret = PTR_ERR(rtap->clk);
185 dev_err(&pdev->dev, "could not get clock\n");
186 return ret;
187 }
188
189 rtap->rtc = devm_rtc_allocate_device(&pdev->dev);
190 if (IS_ERR(rtap->rtc))
191 return PTR_ERR(rtap->rtc);
192
193 rtap->rtc->ops = &coh901331_ops;
194 rtap->rtc->range_max = U32_MAX;
195
196 /* We enable/disable the clock only to assure it works */
197 ret = clk_prepare_enable(rtap->clk);
198 if (ret) {
199 dev_err(&pdev->dev, "could not enable clock\n");
200 return ret;
201 }
202 clk_disable(rtap->clk);
203
204 platform_set_drvdata(pdev, rtap);
205
206 ret = rtc_register_device(rtap->rtc);
207 if (ret)
208 goto out_no_rtc;
209
210 return 0;
211
212 out_no_rtc:
213 clk_unprepare(rtap->clk);
214 return ret;
215 }
216
217 #ifdef CONFIG_PM_SLEEP
coh901331_suspend(struct device * dev)218 static int coh901331_suspend(struct device *dev)
219 {
220 struct coh901331_port *rtap = dev_get_drvdata(dev);
221
222 /*
223 * If this RTC alarm will be used for waking the system up,
224 * don't disable it of course. Else we just disable the alarm
225 * and await suspension.
226 */
227 if (device_may_wakeup(dev)) {
228 enable_irq_wake(rtap->irq);
229 } else {
230 clk_enable(rtap->clk);
231 rtap->irqmaskstore = readl(rtap->virtbase + COH901331_IRQ_MASK);
232 writel(0, rtap->virtbase + COH901331_IRQ_MASK);
233 clk_disable(rtap->clk);
234 }
235 clk_unprepare(rtap->clk);
236 return 0;
237 }
238
coh901331_resume(struct device * dev)239 static int coh901331_resume(struct device *dev)
240 {
241 int ret;
242 struct coh901331_port *rtap = dev_get_drvdata(dev);
243
244 ret = clk_prepare(rtap->clk);
245 if (ret)
246 return ret;
247
248 if (device_may_wakeup(dev)) {
249 disable_irq_wake(rtap->irq);
250 } else {
251 clk_enable(rtap->clk);
252 writel(rtap->irqmaskstore, rtap->virtbase + COH901331_IRQ_MASK);
253 clk_disable(rtap->clk);
254 }
255 return 0;
256 }
257 #endif
258
259 static SIMPLE_DEV_PM_OPS(coh901331_pm_ops, coh901331_suspend, coh901331_resume);
260
coh901331_shutdown(struct platform_device * pdev)261 static void coh901331_shutdown(struct platform_device *pdev)
262 {
263 struct coh901331_port *rtap = platform_get_drvdata(pdev);
264
265 clk_enable(rtap->clk);
266 writel(0, rtap->virtbase + COH901331_IRQ_MASK);
267 clk_disable_unprepare(rtap->clk);
268 }
269
270 static const struct of_device_id coh901331_dt_match[] = {
271 { .compatible = "stericsson,coh901331" },
272 {},
273 };
274 MODULE_DEVICE_TABLE(of, coh901331_dt_match);
275
276 static struct platform_driver coh901331_driver = {
277 .driver = {
278 .name = "rtc-coh901331",
279 .pm = &coh901331_pm_ops,
280 .of_match_table = coh901331_dt_match,
281 },
282 .remove = __exit_p(coh901331_remove),
283 .shutdown = coh901331_shutdown,
284 };
285
286 module_platform_driver_probe(coh901331_driver, coh901331_probe);
287
288 MODULE_AUTHOR("Linus Walleij <linus.walleij@stericsson.com>");
289 MODULE_DESCRIPTION("ST-Ericsson AB COH 901 331 RTC Driver");
290 MODULE_LICENSE("GPL");
291