tjh.dev
Linux kernel mirror (for testing)
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linux
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Real Time Clock (RTC) Driver for i.MX53
4 * Copyright (c) 2004-2011 Freescale Semiconductor, Inc.
5 * Copyright (c) 2017 Beckhoff Automation GmbH & Co. KG
6 */
7
8#include <linux/clk.h>
9#include <linux/io.h>
10#include <linux/module.h>
11#include <linux/platform_device.h>
12#include <linux/rtc.h>
13
14#define SRTC_LPPDR_INIT 0x41736166 /* init for glitch detect */
15
16#define SRTC_LPCR_EN_LP BIT(3) /* lp enable */
17#define SRTC_LPCR_WAE BIT(4) /* lp wakeup alarm enable */
18#define SRTC_LPCR_ALP BIT(7) /* lp alarm flag */
19#define SRTC_LPCR_NSA BIT(11) /* lp non secure access */
20#define SRTC_LPCR_NVE BIT(14) /* lp non valid state exit bit */
21#define SRTC_LPCR_IE BIT(15) /* lp init state exit bit */
22
23#define SRTC_LPSR_ALP BIT(3) /* lp alarm flag */
24#define SRTC_LPSR_NVES BIT(14) /* lp non-valid state exit status */
25#define SRTC_LPSR_IES BIT(15) /* lp init state exit status */
26
27#define SRTC_LPSCMR 0x00 /* LP Secure Counter MSB Reg */
28#define SRTC_LPSCLR 0x04 /* LP Secure Counter LSB Reg */
29#define SRTC_LPSAR 0x08 /* LP Secure Alarm Reg */
30#define SRTC_LPCR 0x10 /* LP Control Reg */
31#define SRTC_LPSR 0x14 /* LP Status Reg */
32#define SRTC_LPPDR 0x18 /* LP Power Supply Glitch Detector Reg */
33
34/* max. number of retries to read registers, 120 was max during test */
35#define REG_READ_TIMEOUT 2000
36
37struct mxc_rtc_data {
38 struct rtc_device *rtc;
39 void __iomem *ioaddr;
40 struct clk *clk;
41 spinlock_t lock; /* protects register access */
42 int irq;
43};
44
45/*
46 * This function does write synchronization for writes to the lp srtc block.
47 * To take care of the asynchronous CKIL clock, all writes from the IP domain
48 * will be synchronized to the CKIL domain.
49 * The caller should hold the pdata->lock
50 */
51static void mxc_rtc_sync_lp_locked(struct device *dev, void __iomem *ioaddr)
52{
53 unsigned int i;
54
55 /* Wait for 3 CKIL cycles */
56 for (i = 0; i < 3; i++) {
57 const u32 count = readl(ioaddr + SRTC_LPSCLR);
58 unsigned int timeout = REG_READ_TIMEOUT;
59
60 while ((readl(ioaddr + SRTC_LPSCLR)) == count) {
61 if (!--timeout) {
62 dev_err_once(dev, "SRTC_LPSCLR stuck! Check your hw.\n");
63 return;
64 }
65 }
66 }
67}
68
69/* This function is the RTC interrupt service routine. */
70static irqreturn_t mxc_rtc_interrupt(int irq, void *dev_id)
71{
72 struct device *dev = dev_id;
73 struct mxc_rtc_data *pdata = dev_get_drvdata(dev);
74 void __iomem *ioaddr = pdata->ioaddr;
75 unsigned long flags;
76 u32 lp_status;
77 u32 lp_cr;
78
79 spin_lock_irqsave(&pdata->lock, flags);
80 if (clk_enable(pdata->clk)) {
81 spin_unlock_irqrestore(&pdata->lock, flags);
82 return IRQ_NONE;
83 }
84
85 lp_status = readl(ioaddr + SRTC_LPSR);
86 lp_cr = readl(ioaddr + SRTC_LPCR);
87
88 /* update irq data & counter */
89 if (lp_status & SRTC_LPSR_ALP) {
90 if (lp_cr & SRTC_LPCR_ALP)
91 rtc_update_irq(pdata->rtc, 1, RTC_AF | RTC_IRQF);
92
93 /* disable further lp alarm interrupts */
94 lp_cr &= ~(SRTC_LPCR_ALP | SRTC_LPCR_WAE);
95 }
96
97 /* Update interrupt enables */
98 writel(lp_cr, ioaddr + SRTC_LPCR);
99
100 /* clear interrupt status */
101 writel(lp_status, ioaddr + SRTC_LPSR);
102
103 mxc_rtc_sync_lp_locked(dev, ioaddr);
104 clk_disable(pdata->clk);
105 spin_unlock_irqrestore(&pdata->lock, flags);
106 return IRQ_HANDLED;
107}
108
109/*
110 * Enable clk and aquire spinlock
111 * @return 0 if successful; non-zero otherwise.
112 */
113static int mxc_rtc_lock(struct mxc_rtc_data *const pdata)
114{
115 int ret;
116
117 spin_lock_irq(&pdata->lock);
118 ret = clk_enable(pdata->clk);
119 if (ret) {
120 spin_unlock_irq(&pdata->lock);
121 return ret;
122 }
123 return 0;
124}
125
126static int mxc_rtc_unlock(struct mxc_rtc_data *const pdata)
127{
128 clk_disable(pdata->clk);
129 spin_unlock_irq(&pdata->lock);
130 return 0;
131}
132
133/*
134 * This function reads the current RTC time into tm in Gregorian date.
135 *
136 * @param tm contains the RTC time value upon return
137 *
138 * @return 0 if successful; non-zero otherwise.
139 */
140static int mxc_rtc_read_time(struct device *dev, struct rtc_time *tm)
141{
142 struct mxc_rtc_data *pdata = dev_get_drvdata(dev);
143 const int clk_failed = clk_enable(pdata->clk);
144
145 if (!clk_failed) {
146 const time64_t now = readl(pdata->ioaddr + SRTC_LPSCMR);
147
148 rtc_time64_to_tm(now, tm);
149 clk_disable(pdata->clk);
150 return 0;
151 }
152 return clk_failed;
153}
154
155/*
156 * This function sets the internal RTC time based on tm in Gregorian date.
157 *
158 * @param tm the time value to be set in the RTC
159 *
160 * @return 0 if successful; non-zero otherwise.
161 */
162static int mxc_rtc_set_time(struct device *dev, struct rtc_time *tm)
163{
164 struct mxc_rtc_data *pdata = dev_get_drvdata(dev);
165 time64_t time = rtc_tm_to_time64(tm);
166 int ret;
167
168 ret = mxc_rtc_lock(pdata);
169 if (ret)
170 return ret;
171
172 writel(time, pdata->ioaddr + SRTC_LPSCMR);
173 mxc_rtc_sync_lp_locked(dev, pdata->ioaddr);
174 return mxc_rtc_unlock(pdata);
175}
176
177/*
178 * This function reads the current alarm value into the passed in \b alrm
179 * argument. It updates the \b alrm's pending field value based on the whether
180 * an alarm interrupt occurs or not.
181 *
182 * @param alrm contains the RTC alarm value upon return
183 *
184 * @return 0 if successful; non-zero otherwise.
185 */
186static int mxc_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
187{
188 struct mxc_rtc_data *pdata = dev_get_drvdata(dev);
189 void __iomem *ioaddr = pdata->ioaddr;
190 int ret;
191
192 ret = mxc_rtc_lock(pdata);
193 if (ret)
194 return ret;
195
196 rtc_time64_to_tm(readl(ioaddr + SRTC_LPSAR), &alrm->time);
197 alrm->pending = !!(readl(ioaddr + SRTC_LPSR) & SRTC_LPSR_ALP);
198 return mxc_rtc_unlock(pdata);
199}
200
201/*
202 * Enable/Disable alarm interrupt
203 * The caller should hold the pdata->lock
204 */
205static void mxc_rtc_alarm_irq_enable_locked(struct mxc_rtc_data *pdata,
206 unsigned int enable)
207{
208 u32 lp_cr = readl(pdata->ioaddr + SRTC_LPCR);
209
210 if (enable)
211 lp_cr |= (SRTC_LPCR_ALP | SRTC_LPCR_WAE);
212 else
213 lp_cr &= ~(SRTC_LPCR_ALP | SRTC_LPCR_WAE);
214
215 writel(lp_cr, pdata->ioaddr + SRTC_LPCR);
216}
217
218static int mxc_rtc_alarm_irq_enable(struct device *dev, unsigned int enable)
219{
220 struct mxc_rtc_data *pdata = dev_get_drvdata(dev);
221 int ret = mxc_rtc_lock(pdata);
222
223 if (ret)
224 return ret;
225
226 mxc_rtc_alarm_irq_enable_locked(pdata, enable);
227 return mxc_rtc_unlock(pdata);
228}
229
230/*
231 * This function sets the RTC alarm based on passed in alrm.
232 *
233 * @param alrm the alarm value to be set in the RTC
234 *
235 * @return 0 if successful; non-zero otherwise.
236 */
237static int mxc_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
238{
239 const time64_t time = rtc_tm_to_time64(&alrm->time);
240 struct mxc_rtc_data *pdata = dev_get_drvdata(dev);
241 int ret = mxc_rtc_lock(pdata);
242
243 if (ret)
244 return ret;
245
246 writel((u32)time, pdata->ioaddr + SRTC_LPSAR);
247
248 /* clear alarm interrupt status bit */
249 writel(SRTC_LPSR_ALP, pdata->ioaddr + SRTC_LPSR);
250 mxc_rtc_sync_lp_locked(dev, pdata->ioaddr);
251
252 mxc_rtc_alarm_irq_enable_locked(pdata, alrm->enabled);
253 mxc_rtc_sync_lp_locked(dev, pdata->ioaddr);
254 mxc_rtc_unlock(pdata);
255 return ret;
256}
257
258static const struct rtc_class_ops mxc_rtc_ops = {
259 .read_time = mxc_rtc_read_time,
260 .set_time = mxc_rtc_set_time,
261 .read_alarm = mxc_rtc_read_alarm,
262 .set_alarm = mxc_rtc_set_alarm,
263 .alarm_irq_enable = mxc_rtc_alarm_irq_enable,
264};
265
266static int mxc_rtc_wait_for_flag(void __iomem *ioaddr, int flag)
267{
268 unsigned int timeout = REG_READ_TIMEOUT;
269
270 while (!(readl(ioaddr) & flag)) {
271 if (!--timeout)
272 return -EBUSY;
273 }
274 return 0;
275}
276
277static int mxc_rtc_probe(struct platform_device *pdev)
278{
279 struct mxc_rtc_data *pdata;
280 struct resource *res;
281 void __iomem *ioaddr;
282 int ret = 0;
283
284 pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
285 if (!pdata)
286 return -ENOMEM;
287
288 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
289 pdata->ioaddr = devm_ioremap_resource(&pdev->dev, res);
290 if (IS_ERR(pdata->ioaddr))
291 return PTR_ERR(pdata->ioaddr);
292
293 ioaddr = pdata->ioaddr;
294
295 pdata->clk = devm_clk_get(&pdev->dev, NULL);
296 if (IS_ERR(pdata->clk)) {
297 dev_err(&pdev->dev, "unable to get rtc clock!\n");
298 return PTR_ERR(pdata->clk);
299 }
300
301 spin_lock_init(&pdata->lock);
302 pdata->irq = platform_get_irq(pdev, 0);
303 if (pdata->irq < 0)
304 return pdata->irq;
305
306 device_init_wakeup(&pdev->dev, 1);
307
308 ret = clk_prepare_enable(pdata->clk);
309 if (ret)
310 return ret;
311 /* initialize glitch detect */
312 writel(SRTC_LPPDR_INIT, ioaddr + SRTC_LPPDR);
313
314 /* clear lp interrupt status */
315 writel(0xFFFFFFFF, ioaddr + SRTC_LPSR);
316
317 /* move out of init state */
318 writel((SRTC_LPCR_IE | SRTC_LPCR_NSA), ioaddr + SRTC_LPCR);
319 ret = mxc_rtc_wait_for_flag(ioaddr + SRTC_LPSR, SRTC_LPSR_IES);
320 if (ret) {
321 dev_err(&pdev->dev, "Timeout waiting for SRTC_LPSR_IES\n");
322 clk_disable_unprepare(pdata->clk);
323 return ret;
324 }
325
326 /* move out of non-valid state */
327 writel((SRTC_LPCR_IE | SRTC_LPCR_NVE | SRTC_LPCR_NSA |
328 SRTC_LPCR_EN_LP), ioaddr + SRTC_LPCR);
329 ret = mxc_rtc_wait_for_flag(ioaddr + SRTC_LPSR, SRTC_LPSR_NVES);
330 if (ret) {
331 dev_err(&pdev->dev, "Timeout waiting for SRTC_LPSR_NVES\n");
332 clk_disable_unprepare(pdata->clk);
333 return ret;
334 }
335
336 pdata->rtc = devm_rtc_allocate_device(&pdev->dev);
337 if (IS_ERR(pdata->rtc))
338 return PTR_ERR(pdata->rtc);
339
340 pdata->rtc->ops = &mxc_rtc_ops;
341 pdata->rtc->range_max = U32_MAX;
342
343 clk_disable(pdata->clk);
344 platform_set_drvdata(pdev, pdata);
345 ret =
346 devm_request_irq(&pdev->dev, pdata->irq, mxc_rtc_interrupt, 0,
347 pdev->name, &pdev->dev);
348 if (ret < 0) {
349 dev_err(&pdev->dev, "interrupt not available.\n");
350 clk_unprepare(pdata->clk);
351 return ret;
352 }
353
354 ret = rtc_register_device(pdata->rtc);
355 if (ret < 0)
356 clk_unprepare(pdata->clk);
357
358 return ret;
359}
360
361static int mxc_rtc_remove(struct platform_device *pdev)
362{
363 struct mxc_rtc_data *pdata = platform_get_drvdata(pdev);
364
365 clk_disable_unprepare(pdata->clk);
366 return 0;
367}
368
369#ifdef CONFIG_PM_SLEEP
370static int mxc_rtc_suspend(struct device *dev)
371{
372 struct mxc_rtc_data *pdata = dev_get_drvdata(dev);
373
374 if (device_may_wakeup(dev))
375 enable_irq_wake(pdata->irq);
376
377 return 0;
378}
379
380static int mxc_rtc_resume(struct device *dev)
381{
382 struct mxc_rtc_data *pdata = dev_get_drvdata(dev);
383
384 if (device_may_wakeup(dev))
385 disable_irq_wake(pdata->irq);
386
387 return 0;
388}
389#endif
390
391static SIMPLE_DEV_PM_OPS(mxc_rtc_pm_ops, mxc_rtc_suspend, mxc_rtc_resume);
392
393static const struct of_device_id mxc_ids[] = {
394 { .compatible = "fsl,imx53-rtc", },
395 {}
396};
397
398static struct platform_driver mxc_rtc_driver = {
399 .driver = {
400 .name = "mxc_rtc_v2",
401 .of_match_table = mxc_ids,
402 .pm = &mxc_rtc_pm_ops,
403 },
404 .probe = mxc_rtc_probe,
405 .remove = mxc_rtc_remove,
406};
407
408module_platform_driver(mxc_rtc_driver);
409
410MODULE_AUTHOR("Freescale Semiconductor, Inc.");
411MODULE_DESCRIPTION("Real Time Clock (RTC) Driver for i.MX53");
412MODULE_LICENSE("GPL");