1/*
  2 * rtc-st-lpc.c - ST's LPC RTC, powered by the Low Power Timer
  3 *
  4 * Copyright (C) 2014 STMicroelectronics Limited
  5 *
  6 * Author: David Paris <david.paris@st.com> for STMicroelectronics
  7 *         Lee Jones <lee.jones@linaro.org> for STMicroelectronics
  8 *
  9 * Based on the original driver written by Stuart Menefy.
 10 *
 11 * This program is free software; you can redistribute it and/or
 12 * modify it under the terms of the GNU General Public Licence
 13 * as published by the Free Software Foundation; either version
 14 * 2 of the Licence, or (at your option) any later version.
 15 */
 16
 17#include <linux/clk.h>
 18#include <linux/delay.h>
 19#include <linux/init.h>
 20#include <linux/io.h>
 21#include <linux/irq.h>
 22#include <linux/kernel.h>
 23#include <linux/module.h>
 24#include <linux/of.h>
 25#include <linux/of_irq.h>
 26#include <linux/platform_device.h>
 27#include <linux/rtc.h>
 28
 29#include <dt-bindings/mfd/st-lpc.h>
 30
 31/* Low Power Timer */
 32#define LPC_LPT_LSB_OFF		0x400
 33#define LPC_LPT_MSB_OFF		0x404
 34#define LPC_LPT_START_OFF	0x408
 35
 36/* Low Power Alarm */
 37#define LPC_LPA_LSB_OFF		0x410
 38#define LPC_LPA_MSB_OFF		0x414
 39#define LPC_LPA_START_OFF	0x418
 40
 41/* LPC as WDT */
 42#define LPC_WDT_OFF		0x510
 43#define LPC_WDT_FLAG_OFF	0x514
 44
 45struct st_rtc {
 46	struct rtc_device *rtc_dev;
 47	struct rtc_wkalrm alarm;
 48	struct resource *res;
 49	struct clk *clk;
 50	unsigned long clkrate;
 51	void __iomem *ioaddr;
 52	bool irq_enabled:1;
 53	spinlock_t lock;
 54	short irq;
 55};
 56
 57static void st_rtc_set_hw_alarm(struct st_rtc *rtc,
 58				unsigned long msb, unsigned long  lsb)
 59{
 60	unsigned long flags;
 61
 62	spin_lock_irqsave(&rtc->lock, flags);
 63
 64	writel_relaxed(1, rtc->ioaddr + LPC_WDT_OFF);
 65
 66	writel_relaxed(msb, rtc->ioaddr + LPC_LPA_MSB_OFF);
 67	writel_relaxed(lsb, rtc->ioaddr + LPC_LPA_LSB_OFF);
 68	writel_relaxed(1, rtc->ioaddr + LPC_LPA_START_OFF);
 69
 70	writel_relaxed(0, rtc->ioaddr + LPC_WDT_OFF);
 71
 72	spin_unlock_irqrestore(&rtc->lock, flags);
 73}
 74
 75static irqreturn_t st_rtc_handler(int this_irq, void *data)
 76{
 77	struct st_rtc *rtc = (struct st_rtc *)data;
 78
 79	rtc_update_irq(rtc->rtc_dev, 1, RTC_AF);
 80
 81	return IRQ_HANDLED;
 82}
 83
 84static int st_rtc_read_time(struct device *dev, struct rtc_time *tm)
 85{
 86	struct st_rtc *rtc = dev_get_drvdata(dev);
 87	unsigned long lpt_lsb, lpt_msb;
 88	unsigned long long lpt;
 89	unsigned long flags;
 90
 91	spin_lock_irqsave(&rtc->lock, flags);
 92
 93	do {
 94		lpt_msb = readl_relaxed(rtc->ioaddr + LPC_LPT_MSB_OFF);
 95		lpt_lsb = readl_relaxed(rtc->ioaddr + LPC_LPT_LSB_OFF);
 96	} while (readl_relaxed(rtc->ioaddr + LPC_LPT_MSB_OFF) != lpt_msb);
 97
 98	spin_unlock_irqrestore(&rtc->lock, flags);
 99
100	lpt = ((unsigned long long)lpt_msb << 32) | lpt_lsb;
101	do_div(lpt, rtc->clkrate);
102	rtc_time64_to_tm(lpt, tm);
103
104	return 0;
105}
106
107static int st_rtc_set_time(struct device *dev, struct rtc_time *tm)
108{
109	struct st_rtc *rtc = dev_get_drvdata(dev);
110	unsigned long long lpt, secs;
111	unsigned long flags;
112
113	secs = rtc_tm_to_time64(tm);
114
115	lpt = (unsigned long long)secs * rtc->clkrate;
116
117	spin_lock_irqsave(&rtc->lock, flags);
118
119	writel_relaxed(lpt >> 32, rtc->ioaddr + LPC_LPT_MSB_OFF);
120	writel_relaxed(lpt, rtc->ioaddr + LPC_LPT_LSB_OFF);
121	writel_relaxed(1, rtc->ioaddr + LPC_LPT_START_OFF);
122
123	spin_unlock_irqrestore(&rtc->lock, flags);
124
125	return 0;
126}
127
128static int st_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *wkalrm)
129{
130	struct st_rtc *rtc = dev_get_drvdata(dev);
131	unsigned long flags;
132
133	spin_lock_irqsave(&rtc->lock, flags);
134
135	memcpy(wkalrm, &rtc->alarm, sizeof(struct rtc_wkalrm));
136
137	spin_unlock_irqrestore(&rtc->lock, flags);
138
139	return 0;
140}
141
142static int st_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
143{
144	struct st_rtc *rtc = dev_get_drvdata(dev);
145
146	if (enabled && !rtc->irq_enabled) {
147		enable_irq(rtc->irq);
148		rtc->irq_enabled = true;
149	} else if (!enabled && rtc->irq_enabled) {
150		disable_irq(rtc->irq);
151		rtc->irq_enabled = false;
152	}
153
154	return 0;
155}
156
157static int st_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *t)
158{
159	struct st_rtc *rtc = dev_get_drvdata(dev);
160	struct rtc_time now;
161	unsigned long long now_secs;
162	unsigned long long alarm_secs;
163	unsigned long long lpa;
164
165	st_rtc_read_time(dev, &now);
166	now_secs = rtc_tm_to_time64(&now);
167	alarm_secs = rtc_tm_to_time64(&t->time);
168
169	/* Invalid alarm time */
170	if (now_secs > alarm_secs)
171		return -EINVAL;
172
173	memcpy(&rtc->alarm, t, sizeof(struct rtc_wkalrm));
174
175	/* Now many secs to fire */
176	alarm_secs -= now_secs;
177	lpa = (unsigned long long)alarm_secs * rtc->clkrate;
178
179	st_rtc_set_hw_alarm(rtc, lpa >> 32, lpa);
180	st_rtc_alarm_irq_enable(dev, t->enabled);
181
182	return 0;
183}
184
185static struct rtc_class_ops st_rtc_ops = {
186	.read_time		= st_rtc_read_time,
187	.set_time		= st_rtc_set_time,
188	.read_alarm		= st_rtc_read_alarm,
189	.set_alarm		= st_rtc_set_alarm,
190	.alarm_irq_enable	= st_rtc_alarm_irq_enable,
191};
192
193static int st_rtc_probe(struct platform_device *pdev)
194{
195	struct device_node *np = pdev->dev.of_node;
196	struct st_rtc *rtc;
197	struct resource *res;
198	uint32_t mode;
199	int ret = 0;
200
201	ret = of_property_read_u32(np, "st,lpc-mode", &mode);
202	if (ret) {
203		dev_err(&pdev->dev, "An LPC mode must be provided\n");
204		return -EINVAL;
205	}
206
207	/* LPC can either run as a Clocksource or in RTC or WDT mode */
208	if (mode != ST_LPC_MODE_RTC)
209		return -ENODEV;
210
211	rtc = devm_kzalloc(&pdev->dev, sizeof(struct st_rtc), GFP_KERNEL);
212	if (!rtc)
213		return -ENOMEM;
214
215	spin_lock_init(&rtc->lock);
216
217	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
218	rtc->ioaddr = devm_ioremap_resource(&pdev->dev, res);
219	if (IS_ERR(rtc->ioaddr))
220		return PTR_ERR(rtc->ioaddr);
221
222	rtc->irq = irq_of_parse_and_map(np, 0);
223	if (!rtc->irq) {
224		dev_err(&pdev->dev, "IRQ missing or invalid\n");
225		return -EINVAL;
226	}
227
228	ret = devm_request_irq(&pdev->dev, rtc->irq, st_rtc_handler, 0,
229			       pdev->name, rtc);
230	if (ret) {
231		dev_err(&pdev->dev, "Failed to request irq %i\n", rtc->irq);
232		return ret;
233	}
234
235	enable_irq_wake(rtc->irq);
236	disable_irq(rtc->irq);
237
238	rtc->clk = clk_get(&pdev->dev, NULL);
239	if (IS_ERR(rtc->clk)) {
240		dev_err(&pdev->dev, "Unable to request clock\n");
241		return PTR_ERR(rtc->clk);
242	}
243
244	clk_prepare_enable(rtc->clk);
245
246	rtc->clkrate = clk_get_rate(rtc->clk);
247	if (!rtc->clkrate) {
248		dev_err(&pdev->dev, "Unable to fetch clock rate\n");
249		return -EINVAL;
250	}
251
252	device_set_wakeup_capable(&pdev->dev, 1);
253
254	platform_set_drvdata(pdev, rtc);
255
256	rtc->rtc_dev = rtc_device_register("st-lpc-rtc", &pdev->dev,
257					   &st_rtc_ops, THIS_MODULE);
258	if (IS_ERR(rtc->rtc_dev)) {
259		clk_disable_unprepare(rtc->clk);
260		return PTR_ERR(rtc->rtc_dev);
261	}
262
263	return 0;
264}
265
266static int st_rtc_remove(struct platform_device *pdev)
267{
268	struct st_rtc *rtc = platform_get_drvdata(pdev);
269
270	if (likely(rtc->rtc_dev))
271		rtc_device_unregister(rtc->rtc_dev);
272
273	return 0;
274}
275
276#ifdef CONFIG_PM_SLEEP
277static int st_rtc_suspend(struct device *dev)
278{
279	struct st_rtc *rtc = dev_get_drvdata(dev);
280
281	if (device_may_wakeup(dev))
282		return 0;
283
284	writel_relaxed(1, rtc->ioaddr + LPC_WDT_OFF);
285	writel_relaxed(0, rtc->ioaddr + LPC_LPA_START_OFF);
286	writel_relaxed(0, rtc->ioaddr + LPC_WDT_OFF);
287
288	return 0;
289}
290
291static int st_rtc_resume(struct device *dev)
292{
293	struct st_rtc *rtc = dev_get_drvdata(dev);
294
295	rtc_alarm_irq_enable(rtc->rtc_dev, 0);
296
297	/*
298	 * clean 'rtc->alarm' to allow a new
299	 * .set_alarm to the upper RTC layer
300	 */
301	memset(&rtc->alarm, 0, sizeof(struct rtc_wkalrm));
302
303	writel_relaxed(0, rtc->ioaddr + LPC_LPA_MSB_OFF);
304	writel_relaxed(0, rtc->ioaddr + LPC_LPA_LSB_OFF);
305	writel_relaxed(1, rtc->ioaddr + LPC_WDT_OFF);
306	writel_relaxed(1, rtc->ioaddr + LPC_LPA_START_OFF);
307	writel_relaxed(0, rtc->ioaddr + LPC_WDT_OFF);
308
309	return 0;
310}
311#endif
312
313static SIMPLE_DEV_PM_OPS(st_rtc_pm_ops, st_rtc_suspend, st_rtc_resume);
314
315static const struct of_device_id st_rtc_match[] = {
316	{ .compatible = "st,stih407-lpc" },
317	{}
318};
319MODULE_DEVICE_TABLE(of, st_rtc_match);
320
321static struct platform_driver st_rtc_platform_driver = {
322	.driver = {
323		.name = "st-lpc-rtc",
324		.pm = &st_rtc_pm_ops,
325		.of_match_table = st_rtc_match,
326	},
327	.probe = st_rtc_probe,
328	.remove = st_rtc_remove,
329};
330
331module_platform_driver(st_rtc_platform_driver);
332
333MODULE_DESCRIPTION("STMicroelectronics LPC RTC driver");
334MODULE_AUTHOR("David Paris <david.paris@st.com>");
335MODULE_LICENSE("GPL");