xref: /linux/drivers/rtc/rtc-mpfs.c (revision 4359a011e259a4608afc7fb3635370c9d4ba5943) 
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Microchip MPFS RTC driver
4  *
5  * Copyright (c) 2021-2022 Microchip Corporation. All rights reserved.
6  *
7  * Author: Daire McNamara <daire.mcnamara@microchip.com>
8  *         & Conor Dooley <conor.dooley@microchip.com>
9  */
10 #include "linux/bits.h"
11 #include "linux/iopoll.h"
12 #include <linux/clk.h>
13 #include <linux/io.h>
14 #include <linux/module.h>
15 #include <linux/kernel.h>
16 #include <linux/of.h>
17 #include <linux/platform_device.h>
18 #include <linux/pm_wakeirq.h>
19 #include <linux/slab.h>
20 #include <linux/rtc.h>
21 
22 #define CONTROL_REG		0x00
23 #define MODE_REG		0x04
24 #define PRESCALER_REG		0x08
25 #define ALARM_LOWER_REG		0x0c
26 #define ALARM_UPPER_REG		0x10
27 #define COMPARE_LOWER_REG	0x14
28 #define COMPARE_UPPER_REG	0x18
29 #define DATETIME_LOWER_REG	0x20
30 #define DATETIME_UPPER_REG	0x24
31 
32 #define CONTROL_RUNNING_BIT	BIT(0)
33 #define CONTROL_START_BIT	BIT(0)
34 #define CONTROL_STOP_BIT	BIT(1)
35 #define CONTROL_ALARM_ON_BIT	BIT(2)
36 #define CONTROL_ALARM_OFF_BIT	BIT(3)
37 #define CONTROL_RESET_BIT	BIT(4)
38 #define CONTROL_UPLOAD_BIT	BIT(5)
39 #define CONTROL_DOWNLOAD_BIT	BIT(6)
40 #define CONTROL_MATCH_BIT	BIT(7)
41 #define CONTROL_WAKEUP_CLR_BIT	BIT(8)
42 #define CONTROL_WAKEUP_SET_BIT	BIT(9)
43 #define CONTROL_UPDATED_BIT	BIT(10)
44 
45 #define MODE_CLOCK_CALENDAR	BIT(0)
46 #define MODE_WAKE_EN		BIT(1)
47 #define MODE_WAKE_RESET		BIT(2)
48 #define MODE_WAKE_CONTINUE	BIT(3)
49 
50 #define MAX_PRESCALER_COUNT	GENMASK(25, 0)
51 #define DATETIME_UPPER_MASK	GENMASK(29, 0)
52 #define ALARM_UPPER_MASK	GENMASK(10, 0)
53 
54 #define UPLOAD_TIMEOUT_US	50
55 
56 struct mpfs_rtc_dev {
57 	struct rtc_device *rtc;
58 	void __iomem *base;
59 };
60 
61 static void mpfs_rtc_start(struct mpfs_rtc_dev *rtcdev)
62 {
63 	u32 ctrl;
64 
65 	ctrl = readl(rtcdev->base + CONTROL_REG);
66 	ctrl &= ~CONTROL_STOP_BIT;
67 	ctrl |= CONTROL_START_BIT;
68 	writel(ctrl, rtcdev->base + CONTROL_REG);
69 }
70 
71 static void mpfs_rtc_clear_irq(struct mpfs_rtc_dev *rtcdev)
72 {
73 	u32 val = readl(rtcdev->base + CONTROL_REG);
74 
75 	val &= ~(CONTROL_ALARM_ON_BIT | CONTROL_STOP_BIT);
76 	val |= CONTROL_ALARM_OFF_BIT;
77 	writel(val, rtcdev->base + CONTROL_REG);
78 	/*
79 	 * Ensure that the posted write to the CONTROL_REG register completed before
80 	 * returning from this function. Not doing this may result in the interrupt
81 	 * only being cleared some time after this function returns.
82 	 */
83 	(void)readl(rtcdev->base + CONTROL_REG);
84 }
85 
86 static int mpfs_rtc_readtime(struct device *dev, struct rtc_time *tm)
87 {
88 	struct mpfs_rtc_dev *rtcdev = dev_get_drvdata(dev);
89 	u64 time;
90 
91 	time = readl(rtcdev->base + DATETIME_LOWER_REG);
92 	time |= ((u64)readl(rtcdev->base + DATETIME_UPPER_REG) & DATETIME_UPPER_MASK) << 32;
93 	rtc_time64_to_tm(time, tm);
94 
95 	return 0;
96 }
97 
98 static int mpfs_rtc_settime(struct device *dev, struct rtc_time *tm)
99 {
100 	struct mpfs_rtc_dev *rtcdev = dev_get_drvdata(dev);
101 	u32 ctrl, prog;
102 	u64 time;
103 	int ret;
104 
105 	time = rtc_tm_to_time64(tm);
106 
107 	writel((u32)time, rtcdev->base + DATETIME_LOWER_REG);
108 	writel((u32)(time >> 32) & DATETIME_UPPER_MASK, rtcdev->base + DATETIME_UPPER_REG);
109 
110 	ctrl = readl(rtcdev->base + CONTROL_REG);
111 	ctrl &= ~CONTROL_STOP_BIT;
112 	ctrl |= CONTROL_UPLOAD_BIT;
113 	writel(ctrl, rtcdev->base + CONTROL_REG);
114 
115 	ret = read_poll_timeout(readl, prog, prog & CONTROL_UPLOAD_BIT, 0, UPLOAD_TIMEOUT_US,
116 				false, rtcdev->base + CONTROL_REG);
117 	if (ret) {
118 		dev_err(dev, "timed out uploading time to rtc");
119 		return ret;
120 	}
121 	mpfs_rtc_start(rtcdev);
122 
123 	return 0;
124 }
125 
126 static int mpfs_rtc_readalarm(struct device *dev, struct rtc_wkalrm *alrm)
127 {
128 	struct mpfs_rtc_dev *rtcdev = dev_get_drvdata(dev);
129 	u32 mode = readl(rtcdev->base + MODE_REG);
130 	u64 time;
131 
132 	alrm->enabled = mode & MODE_WAKE_EN;
133 
134 	time = (u64)readl(rtcdev->base + ALARM_LOWER_REG) << 32;
135 	time |= (readl(rtcdev->base + ALARM_UPPER_REG) & ALARM_UPPER_MASK);
136 	rtc_time64_to_tm(time, &alrm->time);
137 
138 	return 0;
139 }
140 
141 static int mpfs_rtc_setalarm(struct device *dev, struct rtc_wkalrm *alrm)
142 {
143 	struct mpfs_rtc_dev *rtcdev = dev_get_drvdata(dev);
144 	u32 mode, ctrl;
145 	u64 time;
146 
147 	/* Disable the alarm before updating */
148 	ctrl = readl(rtcdev->base + CONTROL_REG);
149 	ctrl |= CONTROL_ALARM_OFF_BIT;
150 	writel(ctrl, rtcdev->base + CONTROL_REG);
151 
152 	time = rtc_tm_to_time64(&alrm->time);
153 
154 	writel((u32)time, rtcdev->base + ALARM_LOWER_REG);
155 	writel((u32)(time >> 32) & ALARM_UPPER_MASK, rtcdev->base + ALARM_UPPER_REG);
156 
157 	/* Bypass compare register in alarm mode */
158 	writel(GENMASK(31, 0), rtcdev->base + COMPARE_LOWER_REG);
159 	writel(GENMASK(29, 0), rtcdev->base + COMPARE_UPPER_REG);
160 
161 	/* Configure the RTC to enable the alarm. */
162 	ctrl = readl(rtcdev->base + CONTROL_REG);
163 	mode = readl(rtcdev->base + MODE_REG);
164 	if (alrm->enabled) {
165 		mode = MODE_WAKE_EN | MODE_WAKE_CONTINUE;
166 		/* Enable the alarm */
167 		ctrl &= ~CONTROL_ALARM_OFF_BIT;
168 		ctrl |= CONTROL_ALARM_ON_BIT;
169 	}
170 	ctrl &= ~CONTROL_STOP_BIT;
171 	ctrl |= CONTROL_START_BIT;
172 	writel(ctrl, rtcdev->base + CONTROL_REG);
173 	writel(mode, rtcdev->base + MODE_REG);
174 
175 	return 0;
176 }
177 
178 static int mpfs_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
179 {
180 	struct mpfs_rtc_dev *rtcdev = dev_get_drvdata(dev);
181 	u32 ctrl;
182 
183 	ctrl = readl(rtcdev->base + CONTROL_REG);
184 	ctrl &= ~(CONTROL_ALARM_ON_BIT | CONTROL_ALARM_OFF_BIT | CONTROL_STOP_BIT);
185 
186 	if (enabled)
187 		ctrl |= CONTROL_ALARM_ON_BIT;
188 	else
189 		ctrl |= CONTROL_ALARM_OFF_BIT;
190 
191 	writel(ctrl, rtcdev->base + CONTROL_REG);
192 
193 	return 0;
194 }
195 
196 static inline struct clk *mpfs_rtc_init_clk(struct device *dev)
197 {
198 	struct clk *clk;
199 	int ret;
200 
201 	clk = devm_clk_get(dev, "rtc");
202 	if (IS_ERR(clk))
203 		return clk;
204 
205 	ret = clk_prepare_enable(clk);
206 	if (ret)
207 		return ERR_PTR(ret);
208 
209 	devm_add_action_or_reset(dev, (void (*) (void *))clk_disable_unprepare, clk);
210 	return clk;
211 }
212 
213 static irqreturn_t mpfs_rtc_wakeup_irq_handler(int irq, void *dev)
214 {
215 	struct mpfs_rtc_dev *rtcdev = dev;
216 
217 	mpfs_rtc_clear_irq(rtcdev);
218 
219 	rtc_update_irq(rtcdev->rtc, 1, RTC_IRQF | RTC_AF);
220 
221 	return IRQ_HANDLED;
222 }
223 
224 static const struct rtc_class_ops mpfs_rtc_ops = {
225 	.read_time		= mpfs_rtc_readtime,
226 	.set_time		= mpfs_rtc_settime,
227 	.read_alarm		= mpfs_rtc_readalarm,
228 	.set_alarm		= mpfs_rtc_setalarm,
229 	.alarm_irq_enable	= mpfs_rtc_alarm_irq_enable,
230 };
231 
232 static int mpfs_rtc_probe(struct platform_device *pdev)
233 {
234 	struct mpfs_rtc_dev *rtcdev;
235 	struct clk *clk;
236 	u32 prescaler;
237 	int wakeup_irq, ret;
238 
239 	rtcdev = devm_kzalloc(&pdev->dev, sizeof(struct mpfs_rtc_dev), GFP_KERNEL);
240 	if (!rtcdev)
241 		return -ENOMEM;
242 
243 	platform_set_drvdata(pdev, rtcdev);
244 
245 	rtcdev->rtc = devm_rtc_allocate_device(&pdev->dev);
246 	if (IS_ERR(rtcdev->rtc))
247 		return PTR_ERR(rtcdev->rtc);
248 
249 	rtcdev->rtc->ops = &mpfs_rtc_ops;
250 
251 	/* range is capped by alarm max, lower reg is 31:0 & upper is 10:0 */
252 	rtcdev->rtc->range_max = GENMASK_ULL(42, 0);
253 
254 	clk = mpfs_rtc_init_clk(&pdev->dev);
255 	if (IS_ERR(clk))
256 		return PTR_ERR(clk);
257 
258 	rtcdev->base = devm_platform_ioremap_resource(pdev, 0);
259 	if (IS_ERR(rtcdev->base)) {
260 		dev_dbg(&pdev->dev, "invalid ioremap resources\n");
261 		return PTR_ERR(rtcdev->base);
262 	}
263 
264 	wakeup_irq = platform_get_irq(pdev, 0);
265 	if (wakeup_irq <= 0) {
266 		dev_dbg(&pdev->dev, "could not get wakeup irq\n");
267 		return wakeup_irq;
268 	}
269 	ret = devm_request_irq(&pdev->dev, wakeup_irq, mpfs_rtc_wakeup_irq_handler, 0,
270 			       dev_name(&pdev->dev), rtcdev);
271 	if (ret) {
272 		dev_dbg(&pdev->dev, "could not request wakeup irq\n");
273 		return ret;
274 	}
275 
276 	/* prescaler hardware adds 1 to reg value */
277 	prescaler = clk_get_rate(devm_clk_get(&pdev->dev, "rtcref")) - 1;
278 
279 	if (prescaler > MAX_PRESCALER_COUNT) {
280 		dev_dbg(&pdev->dev, "invalid prescaler %d\n", prescaler);
281 		return -EINVAL;
282 	}
283 
284 	writel(prescaler, rtcdev->base + PRESCALER_REG);
285 	dev_info(&pdev->dev, "prescaler set to: 0x%X \r\n", prescaler);
286 
287 	device_init_wakeup(&pdev->dev, true);
288 	ret = dev_pm_set_wake_irq(&pdev->dev, wakeup_irq);
289 	if (ret)
290 		dev_err(&pdev->dev, "failed to enable irq wake\n");
291 
292 	return devm_rtc_register_device(rtcdev->rtc);
293 }
294 
295 static int mpfs_rtc_remove(struct platform_device *pdev)
296 {
297 	dev_pm_clear_wake_irq(&pdev->dev);
298 
299 	return 0;
300 }
301 
302 static const struct of_device_id mpfs_rtc_of_match[] = {
303 	{ .compatible = "microchip,mpfs-rtc" },
304 	{ }
305 };
306 
307 MODULE_DEVICE_TABLE(of, mpfs_rtc_of_match);
308 
309 static struct platform_driver mpfs_rtc_driver = {
310 	.probe = mpfs_rtc_probe,
311 	.remove = mpfs_rtc_remove,
312 	.driver	= {
313 		.name = "mpfs_rtc",
314 		.of_match_table = mpfs_rtc_of_match,
315 	},
316 };
317 
318 module_platform_driver(mpfs_rtc_driver);
319 
320 MODULE_DESCRIPTION("Real time clock for Microchip Polarfire SoC");
321 MODULE_AUTHOR("Daire McNamara <daire.mcnamara@microchip.com>");
322 MODULE_AUTHOR("Conor Dooley <conor.dooley@microchip.com>");
323 MODULE_LICENSE("GPL");
324