1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 * APM X-Gene SoC Real Time Clock Driver
4 *
5 * Copyright (c) 2014, Applied Micro Circuits Corporation
6 * Author: Rameshwar Prasad Sahu <rsahu@apm.com>
7 * Loc Ho <lho@apm.com>
8 */
9
10 #include <linux/clk.h>
11 #include <linux/delay.h>
12 #include <linux/init.h>
13 #include <linux/io.h>
14 #include <linux/module.h>
15 #include <linux/of.h>
16 #include <linux/platform_device.h>
17 #include <linux/rtc.h>
18 #include <linux/slab.h>
19
20 /* RTC CSR Registers */
21 #define RTC_CCVR 0x00
22 #define RTC_CMR 0x04
23 #define RTC_CLR 0x08
24 #define RTC_CCR 0x0C
25 #define RTC_CCR_IE BIT(0)
26 #define RTC_CCR_MASK BIT(1)
27 #define RTC_CCR_EN BIT(2)
28 #define RTC_CCR_WEN BIT(3)
29 #define RTC_STAT 0x10
30 #define RTC_STAT_BIT BIT(0)
31 #define RTC_RSTAT 0x14
32 #define RTC_EOI 0x18
33 #define RTC_VER 0x1C
34
35 struct xgene_rtc_dev {
36 struct rtc_device *rtc;
37 void __iomem *csr_base;
38 struct clk *clk;
39 unsigned int irq_wake;
40 unsigned int irq_enabled;
41 };
42
xgene_rtc_read_time(struct device * dev,struct rtc_time * tm)43 static int xgene_rtc_read_time(struct device *dev, struct rtc_time *tm)
44 {
45 struct xgene_rtc_dev *pdata = dev_get_drvdata(dev);
46
47 rtc_time64_to_tm(readl(pdata->csr_base + RTC_CCVR), tm);
48 return 0;
49 }
50
xgene_rtc_set_time(struct device * dev,struct rtc_time * tm)51 static int xgene_rtc_set_time(struct device *dev, struct rtc_time *tm)
52 {
53 struct xgene_rtc_dev *pdata = dev_get_drvdata(dev);
54
55 /*
56 * NOTE: After the following write, the RTC_CCVR is only reflected
57 * after the update cycle of 1 seconds.
58 */
59 writel((u32)rtc_tm_to_time64(tm), pdata->csr_base + RTC_CLR);
60 readl(pdata->csr_base + RTC_CLR); /* Force a barrier */
61
62 return 0;
63 }
64
xgene_rtc_read_alarm(struct device * dev,struct rtc_wkalrm * alrm)65 static int xgene_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
66 {
67 struct xgene_rtc_dev *pdata = dev_get_drvdata(dev);
68
69 /* If possible, CMR should be read here */
70 rtc_time64_to_tm(0, &alrm->time);
71 alrm->enabled = readl(pdata->csr_base + RTC_CCR) & RTC_CCR_IE;
72
73 return 0;
74 }
75
xgene_rtc_alarm_irq_enable(struct device * dev,u32 enabled)76 static int xgene_rtc_alarm_irq_enable(struct device *dev, u32 enabled)
77 {
78 struct xgene_rtc_dev *pdata = dev_get_drvdata(dev);
79 u32 ccr;
80
81 ccr = readl(pdata->csr_base + RTC_CCR);
82 if (enabled) {
83 ccr &= ~RTC_CCR_MASK;
84 ccr |= RTC_CCR_IE;
85 } else {
86 ccr &= ~RTC_CCR_IE;
87 ccr |= RTC_CCR_MASK;
88 }
89 writel(ccr, pdata->csr_base + RTC_CCR);
90
91 return 0;
92 }
93
xgene_rtc_alarm_irq_enabled(struct device * dev)94 static int xgene_rtc_alarm_irq_enabled(struct device *dev)
95 {
96 struct xgene_rtc_dev *pdata = dev_get_drvdata(dev);
97
98 return readl(pdata->csr_base + RTC_CCR) & RTC_CCR_IE ? 1 : 0;
99 }
100
xgene_rtc_set_alarm(struct device * dev,struct rtc_wkalrm * alrm)101 static int xgene_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
102 {
103 struct xgene_rtc_dev *pdata = dev_get_drvdata(dev);
104
105 writel((u32)rtc_tm_to_time64(&alrm->time), pdata->csr_base + RTC_CMR);
106
107 xgene_rtc_alarm_irq_enable(dev, alrm->enabled);
108
109 return 0;
110 }
111
112 static const struct rtc_class_ops xgene_rtc_ops = {
113 .read_time = xgene_rtc_read_time,
114 .set_time = xgene_rtc_set_time,
115 .read_alarm = xgene_rtc_read_alarm,
116 .set_alarm = xgene_rtc_set_alarm,
117 .alarm_irq_enable = xgene_rtc_alarm_irq_enable,
118 };
119
xgene_rtc_interrupt(int irq,void * id)120 static irqreturn_t xgene_rtc_interrupt(int irq, void *id)
121 {
122 struct xgene_rtc_dev *pdata = id;
123
124 /* Check if interrupt asserted */
125 if (!(readl(pdata->csr_base + RTC_STAT) & RTC_STAT_BIT))
126 return IRQ_NONE;
127
128 /* Clear interrupt */
129 readl(pdata->csr_base + RTC_EOI);
130
131 rtc_update_irq(pdata->rtc, 1, RTC_IRQF | RTC_AF);
132
133 return IRQ_HANDLED;
134 }
135
xgene_rtc_probe(struct platform_device * pdev)136 static int xgene_rtc_probe(struct platform_device *pdev)
137 {
138 struct xgene_rtc_dev *pdata;
139 int ret;
140 int irq;
141
142 pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
143 if (!pdata)
144 return -ENOMEM;
145 platform_set_drvdata(pdev, pdata);
146
147 pdata->csr_base = devm_platform_ioremap_resource(pdev, 0);
148 if (IS_ERR(pdata->csr_base))
149 return PTR_ERR(pdata->csr_base);
150
151 pdata->rtc = devm_rtc_allocate_device(&pdev->dev);
152 if (IS_ERR(pdata->rtc))
153 return PTR_ERR(pdata->rtc);
154
155 irq = platform_get_irq(pdev, 0);
156 if (irq < 0)
157 return irq;
158 ret = devm_request_irq(&pdev->dev, irq, xgene_rtc_interrupt, 0,
159 dev_name(&pdev->dev), pdata);
160 if (ret) {
161 dev_err(&pdev->dev, "Could not request IRQ\n");
162 return ret;
163 }
164
165 pdata->clk = devm_clk_get(&pdev->dev, NULL);
166 if (IS_ERR(pdata->clk)) {
167 dev_err(&pdev->dev, "Couldn't get the clock for RTC\n");
168 return -ENODEV;
169 }
170 ret = clk_prepare_enable(pdata->clk);
171 if (ret)
172 return ret;
173
174 /* Turn on the clock and the crystal */
175 writel(RTC_CCR_EN, pdata->csr_base + RTC_CCR);
176
177 ret = device_init_wakeup(&pdev->dev, 1);
178 if (ret) {
179 clk_disable_unprepare(pdata->clk);
180 return ret;
181 }
182
183 pdata->rtc->ops = &xgene_rtc_ops;
184 pdata->rtc->range_max = U32_MAX;
185
186 ret = devm_rtc_register_device(pdata->rtc);
187 if (ret) {
188 clk_disable_unprepare(pdata->clk);
189 return ret;
190 }
191
192 return 0;
193 }
194
xgene_rtc_remove(struct platform_device * pdev)195 static void xgene_rtc_remove(struct platform_device *pdev)
196 {
197 struct xgene_rtc_dev *pdata = platform_get_drvdata(pdev);
198
199 xgene_rtc_alarm_irq_enable(&pdev->dev, 0);
200 device_init_wakeup(&pdev->dev, 0);
201 clk_disable_unprepare(pdata->clk);
202 }
203
xgene_rtc_suspend(struct device * dev)204 static int __maybe_unused xgene_rtc_suspend(struct device *dev)
205 {
206 struct platform_device *pdev = to_platform_device(dev);
207 struct xgene_rtc_dev *pdata = platform_get_drvdata(pdev);
208 int irq;
209
210 irq = platform_get_irq(pdev, 0);
211
212 /*
213 * If this RTC alarm will be used for waking the system up,
214 * don't disable it of course. Else we just disable the alarm
215 * and await suspension.
216 */
217 if (device_may_wakeup(&pdev->dev)) {
218 if (!enable_irq_wake(irq))
219 pdata->irq_wake = 1;
220 } else {
221 pdata->irq_enabled = xgene_rtc_alarm_irq_enabled(dev);
222 xgene_rtc_alarm_irq_enable(dev, 0);
223 clk_disable_unprepare(pdata->clk);
224 }
225 return 0;
226 }
227
xgene_rtc_resume(struct device * dev)228 static int __maybe_unused xgene_rtc_resume(struct device *dev)
229 {
230 struct platform_device *pdev = to_platform_device(dev);
231 struct xgene_rtc_dev *pdata = platform_get_drvdata(pdev);
232 int irq;
233 int rc;
234
235 irq = platform_get_irq(pdev, 0);
236
237 if (device_may_wakeup(&pdev->dev)) {
238 if (pdata->irq_wake) {
239 disable_irq_wake(irq);
240 pdata->irq_wake = 0;
241 }
242 } else {
243 rc = clk_prepare_enable(pdata->clk);
244 if (rc) {
245 dev_err(dev, "Unable to enable clock error %d\n", rc);
246 return rc;
247 }
248 xgene_rtc_alarm_irq_enable(dev, pdata->irq_enabled);
249 }
250
251 return 0;
252 }
253
254 static SIMPLE_DEV_PM_OPS(xgene_rtc_pm_ops, xgene_rtc_suspend, xgene_rtc_resume);
255
256 #ifdef CONFIG_OF
257 static const struct of_device_id xgene_rtc_of_match[] = {
258 {.compatible = "apm,xgene-rtc" },
259 { }
260 };
261 MODULE_DEVICE_TABLE(of, xgene_rtc_of_match);
262 #endif
263
264 static struct platform_driver xgene_rtc_driver = {
265 .probe = xgene_rtc_probe,
266 .remove_new = xgene_rtc_remove,
267 .driver = {
268 .name = "xgene-rtc",
269 .pm = &xgene_rtc_pm_ops,
270 .of_match_table = of_match_ptr(xgene_rtc_of_match),
271 },
272 };
273
274 module_platform_driver(xgene_rtc_driver);
275
276 MODULE_DESCRIPTION("APM X-Gene SoC RTC driver");
277 MODULE_AUTHOR("Rameshwar Sahu <rsahu@apm.com>");
278 MODULE_LICENSE("GPL");
279