1 | // SPDX-License-Identifier: GPL-2.0-or-later |
2 | /* |
3 | * rtc-st-lpc.c - ST's LPC RTC, powered by the Low Power Timer |
4 | * |
5 | * Copyright (C) 2014 STMicroelectronics Limited |
6 | * |
7 | * Author: David Paris <david.paris@st.com> for STMicroelectronics |
8 | * Lee Jones <lee.jones@linaro.org> for STMicroelectronics |
9 | * |
10 | * Based on the original driver written by Stuart Menefy. |
11 | */ |
12 | |
13 | #include <linux/clk.h> |
14 | #include <linux/delay.h> |
15 | #include <linux/init.h> |
16 | #include <linux/io.h> |
17 | #include <linux/irq.h> |
18 | #include <linux/kernel.h> |
19 | #include <linux/module.h> |
20 | #include <linux/of.h> |
21 | #include <linux/of_irq.h> |
22 | #include <linux/platform_device.h> |
23 | #include <linux/rtc.h> |
24 | |
25 | #include <dt-bindings/mfd/st-lpc.h> |
26 | |
27 | /* Low Power Timer */ |
28 | #define LPC_LPT_LSB_OFF 0x400 |
29 | #define LPC_LPT_MSB_OFF 0x404 |
30 | #define LPC_LPT_START_OFF 0x408 |
31 | |
32 | /* Low Power Alarm */ |
33 | #define LPC_LPA_LSB_OFF 0x410 |
34 | #define LPC_LPA_MSB_OFF 0x414 |
35 | #define LPC_LPA_START_OFF 0x418 |
36 | |
37 | /* LPC as WDT */ |
38 | #define LPC_WDT_OFF 0x510 |
39 | #define LPC_WDT_FLAG_OFF 0x514 |
40 | |
41 | struct st_rtc { |
42 | struct rtc_device *rtc_dev; |
43 | struct rtc_wkalrm alarm; |
44 | struct clk *clk; |
45 | unsigned long clkrate; |
46 | void __iomem *ioaddr; |
47 | bool irq_enabled:1; |
48 | spinlock_t lock; |
49 | short irq; |
50 | }; |
51 | |
52 | static void st_rtc_set_hw_alarm(struct st_rtc *rtc, |
53 | unsigned long msb, unsigned long lsb) |
54 | { |
55 | unsigned long flags; |
56 | |
57 | spin_lock_irqsave(&rtc->lock, flags); |
58 | |
59 | writel_relaxed(1, rtc->ioaddr + LPC_WDT_OFF); |
60 | |
61 | writel_relaxed(msb, rtc->ioaddr + LPC_LPA_MSB_OFF); |
62 | writel_relaxed(lsb, rtc->ioaddr + LPC_LPA_LSB_OFF); |
63 | writel_relaxed(1, rtc->ioaddr + LPC_LPA_START_OFF); |
64 | |
65 | writel_relaxed(0, rtc->ioaddr + LPC_WDT_OFF); |
66 | |
67 | spin_unlock_irqrestore(lock: &rtc->lock, flags); |
68 | } |
69 | |
70 | static irqreturn_t st_rtc_handler(int this_irq, void *data) |
71 | { |
72 | struct st_rtc *rtc = (struct st_rtc *)data; |
73 | |
74 | rtc_update_irq(rtc: rtc->rtc_dev, num: 1, RTC_AF); |
75 | |
76 | return IRQ_HANDLED; |
77 | } |
78 | |
79 | static int st_rtc_read_time(struct device *dev, struct rtc_time *tm) |
80 | { |
81 | struct st_rtc *rtc = dev_get_drvdata(dev); |
82 | unsigned long lpt_lsb, lpt_msb; |
83 | unsigned long long lpt; |
84 | unsigned long flags; |
85 | |
86 | spin_lock_irqsave(&rtc->lock, flags); |
87 | |
88 | do { |
89 | lpt_msb = readl_relaxed(rtc->ioaddr + LPC_LPT_MSB_OFF); |
90 | lpt_lsb = readl_relaxed(rtc->ioaddr + LPC_LPT_LSB_OFF); |
91 | } while (readl_relaxed(rtc->ioaddr + LPC_LPT_MSB_OFF) != lpt_msb); |
92 | |
93 | spin_unlock_irqrestore(lock: &rtc->lock, flags); |
94 | |
95 | lpt = ((unsigned long long)lpt_msb << 32) | lpt_lsb; |
96 | do_div(lpt, rtc->clkrate); |
97 | rtc_time64_to_tm(time: lpt, tm); |
98 | |
99 | return 0; |
100 | } |
101 | |
102 | static int st_rtc_set_time(struct device *dev, struct rtc_time *tm) |
103 | { |
104 | struct st_rtc *rtc = dev_get_drvdata(dev); |
105 | unsigned long long lpt, secs; |
106 | unsigned long flags; |
107 | |
108 | secs = rtc_tm_to_time64(tm); |
109 | |
110 | lpt = (unsigned long long)secs * rtc->clkrate; |
111 | |
112 | spin_lock_irqsave(&rtc->lock, flags); |
113 | |
114 | writel_relaxed(lpt >> 32, rtc->ioaddr + LPC_LPT_MSB_OFF); |
115 | writel_relaxed(lpt, rtc->ioaddr + LPC_LPT_LSB_OFF); |
116 | writel_relaxed(1, rtc->ioaddr + LPC_LPT_START_OFF); |
117 | |
118 | spin_unlock_irqrestore(lock: &rtc->lock, flags); |
119 | |
120 | return 0; |
121 | } |
122 | |
123 | static int st_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *wkalrm) |
124 | { |
125 | struct st_rtc *rtc = dev_get_drvdata(dev); |
126 | unsigned long flags; |
127 | |
128 | spin_lock_irqsave(&rtc->lock, flags); |
129 | |
130 | memcpy(wkalrm, &rtc->alarm, sizeof(struct rtc_wkalrm)); |
131 | |
132 | spin_unlock_irqrestore(lock: &rtc->lock, flags); |
133 | |
134 | return 0; |
135 | } |
136 | |
137 | static int st_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled) |
138 | { |
139 | struct st_rtc *rtc = dev_get_drvdata(dev); |
140 | |
141 | if (enabled && !rtc->irq_enabled) { |
142 | enable_irq(irq: rtc->irq); |
143 | rtc->irq_enabled = true; |
144 | } else if (!enabled && rtc->irq_enabled) { |
145 | disable_irq(irq: rtc->irq); |
146 | rtc->irq_enabled = false; |
147 | } |
148 | |
149 | return 0; |
150 | } |
151 | |
152 | static int st_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *t) |
153 | { |
154 | struct st_rtc *rtc = dev_get_drvdata(dev); |
155 | struct rtc_time now; |
156 | unsigned long long now_secs; |
157 | unsigned long long alarm_secs; |
158 | unsigned long long lpa; |
159 | |
160 | st_rtc_read_time(dev, tm: &now); |
161 | now_secs = rtc_tm_to_time64(tm: &now); |
162 | alarm_secs = rtc_tm_to_time64(tm: &t->time); |
163 | |
164 | memcpy(&rtc->alarm, t, sizeof(struct rtc_wkalrm)); |
165 | |
166 | /* Now many secs to fire */ |
167 | alarm_secs -= now_secs; |
168 | lpa = (unsigned long long)alarm_secs * rtc->clkrate; |
169 | |
170 | st_rtc_set_hw_alarm(rtc, msb: lpa >> 32, lsb: lpa); |
171 | st_rtc_alarm_irq_enable(dev, enabled: t->enabled); |
172 | |
173 | return 0; |
174 | } |
175 | |
176 | static const struct rtc_class_ops st_rtc_ops = { |
177 | .read_time = st_rtc_read_time, |
178 | .set_time = st_rtc_set_time, |
179 | .read_alarm = st_rtc_read_alarm, |
180 | .set_alarm = st_rtc_set_alarm, |
181 | .alarm_irq_enable = st_rtc_alarm_irq_enable, |
182 | }; |
183 | |
184 | static int st_rtc_probe(struct platform_device *pdev) |
185 | { |
186 | struct device_node *np = pdev->dev.of_node; |
187 | struct st_rtc *rtc; |
188 | uint32_t mode; |
189 | int ret = 0; |
190 | |
191 | ret = of_property_read_u32(np, propname: "st,lpc-mode" , out_value: &mode); |
192 | if (ret) { |
193 | dev_err(&pdev->dev, "An LPC mode must be provided\n" ); |
194 | return -EINVAL; |
195 | } |
196 | |
197 | /* LPC can either run as a Clocksource or in RTC or WDT mode */ |
198 | if (mode != ST_LPC_MODE_RTC) |
199 | return -ENODEV; |
200 | |
201 | rtc = devm_kzalloc(dev: &pdev->dev, size: sizeof(struct st_rtc), GFP_KERNEL); |
202 | if (!rtc) |
203 | return -ENOMEM; |
204 | |
205 | rtc->rtc_dev = devm_rtc_allocate_device(dev: &pdev->dev); |
206 | if (IS_ERR(ptr: rtc->rtc_dev)) |
207 | return PTR_ERR(ptr: rtc->rtc_dev); |
208 | |
209 | spin_lock_init(&rtc->lock); |
210 | |
211 | rtc->ioaddr = devm_platform_ioremap_resource(pdev, index: 0); |
212 | if (IS_ERR(ptr: rtc->ioaddr)) |
213 | return PTR_ERR(ptr: rtc->ioaddr); |
214 | |
215 | rtc->irq = irq_of_parse_and_map(node: np, index: 0); |
216 | if (!rtc->irq) { |
217 | dev_err(&pdev->dev, "IRQ missing or invalid\n" ); |
218 | return -EINVAL; |
219 | } |
220 | |
221 | ret = devm_request_irq(dev: &pdev->dev, irq: rtc->irq, handler: st_rtc_handler, irqflags: 0, |
222 | devname: pdev->name, dev_id: rtc); |
223 | if (ret) { |
224 | dev_err(&pdev->dev, "Failed to request irq %i\n" , rtc->irq); |
225 | return ret; |
226 | } |
227 | |
228 | enable_irq_wake(irq: rtc->irq); |
229 | disable_irq(irq: rtc->irq); |
230 | |
231 | rtc->clk = devm_clk_get_enabled(dev: &pdev->dev, NULL); |
232 | if (IS_ERR(ptr: rtc->clk)) |
233 | return dev_err_probe(dev: &pdev->dev, err: PTR_ERR(ptr: rtc->clk), |
234 | fmt: "Unable to request clock\n" ); |
235 | |
236 | rtc->clkrate = clk_get_rate(clk: rtc->clk); |
237 | if (!rtc->clkrate) { |
238 | dev_err(&pdev->dev, "Unable to fetch clock rate\n" ); |
239 | return -EINVAL; |
240 | } |
241 | |
242 | device_set_wakeup_capable(dev: &pdev->dev, capable: 1); |
243 | |
244 | platform_set_drvdata(pdev, data: rtc); |
245 | |
246 | rtc->rtc_dev->ops = &st_rtc_ops; |
247 | rtc->rtc_dev->range_max = U64_MAX; |
248 | do_div(rtc->rtc_dev->range_max, rtc->clkrate); |
249 | |
250 | ret = devm_rtc_register_device(rtc->rtc_dev); |
251 | if (ret) |
252 | return ret; |
253 | |
254 | return 0; |
255 | } |
256 | |
257 | #ifdef CONFIG_PM_SLEEP |
258 | static int st_rtc_suspend(struct device *dev) |
259 | { |
260 | struct st_rtc *rtc = dev_get_drvdata(dev); |
261 | |
262 | if (device_may_wakeup(dev)) |
263 | return 0; |
264 | |
265 | writel_relaxed(1, rtc->ioaddr + LPC_WDT_OFF); |
266 | writel_relaxed(0, rtc->ioaddr + LPC_LPA_START_OFF); |
267 | writel_relaxed(0, rtc->ioaddr + LPC_WDT_OFF); |
268 | |
269 | return 0; |
270 | } |
271 | |
272 | static int st_rtc_resume(struct device *dev) |
273 | { |
274 | struct st_rtc *rtc = dev_get_drvdata(dev); |
275 | |
276 | rtc_alarm_irq_enable(rtc: rtc->rtc_dev, enabled: 0); |
277 | |
278 | /* |
279 | * clean 'rtc->alarm' to allow a new |
280 | * .set_alarm to the upper RTC layer |
281 | */ |
282 | memset(&rtc->alarm, 0, sizeof(struct rtc_wkalrm)); |
283 | |
284 | writel_relaxed(0, rtc->ioaddr + LPC_LPA_MSB_OFF); |
285 | writel_relaxed(0, rtc->ioaddr + LPC_LPA_LSB_OFF); |
286 | writel_relaxed(1, rtc->ioaddr + LPC_WDT_OFF); |
287 | writel_relaxed(1, rtc->ioaddr + LPC_LPA_START_OFF); |
288 | writel_relaxed(0, rtc->ioaddr + LPC_WDT_OFF); |
289 | |
290 | return 0; |
291 | } |
292 | #endif |
293 | |
294 | static SIMPLE_DEV_PM_OPS(st_rtc_pm_ops, st_rtc_suspend, st_rtc_resume); |
295 | |
296 | static const struct of_device_id st_rtc_match[] = { |
297 | { .compatible = "st,stih407-lpc" }, |
298 | {} |
299 | }; |
300 | MODULE_DEVICE_TABLE(of, st_rtc_match); |
301 | |
302 | static struct platform_driver st_rtc_platform_driver = { |
303 | .driver = { |
304 | .name = "st-lpc-rtc" , |
305 | .pm = &st_rtc_pm_ops, |
306 | .of_match_table = st_rtc_match, |
307 | }, |
308 | .probe = st_rtc_probe, |
309 | }; |
310 | |
311 | module_platform_driver(st_rtc_platform_driver); |
312 | |
313 | MODULE_DESCRIPTION("STMicroelectronics LPC RTC driver" ); |
314 | MODULE_AUTHOR("David Paris <david.paris@st.com>" ); |
315 | MODULE_LICENSE("GPL" ); |
316 | |