1/*
2 * Copyright (C) 2007-2009 ST-Ericsson AB
3 * License terms: GNU General Public License (GPL) version 2
4 * RTC clock driver for the AB3100 Analog Baseband Chip
5 * Author: Linus Walleij <linus.walleij@stericsson.com>
6 */
7#include <linux/module.h>
8#include <linux/kernel.h>
9#include <linux/init.h>
10#include <linux/platform_device.h>
11#include <linux/rtc.h>
12#include <linux/mfd/abx500.h>
13
14/* Clock rate in Hz */
15#define AB3100_RTC_CLOCK_RATE	32768
16
17/*
18 * The AB3100 RTC registers. These are the same for
19 * AB3000 and AB3100.
20 * Control register:
21 * Bit 0: RTC Monitor cleared=0, active=1, if you set it
22 *        to 1 it remains active until RTC power is lost.
23 * Bit 1: 32 kHz Oscillator, 0 = on, 1 = bypass
24 * Bit 2: Alarm on, 0 = off, 1 = on
25 * Bit 3: 32 kHz buffer disabling, 0 = enabled, 1 = disabled
26 */
27#define AB3100_RTC		0x53
28/* default setting, buffer disabled, alarm on */
29#define RTC_SETTING		0x30
30/* Alarm when AL0-AL3 == TI0-TI3  */
31#define AB3100_AL0		0x56
32#define AB3100_AL1		0x57
33#define AB3100_AL2		0x58
34#define AB3100_AL3		0x59
35/* This 48-bit register that counts up at 32768 Hz */
36#define AB3100_TI0		0x5a
37#define AB3100_TI1		0x5b
38#define AB3100_TI2		0x5c
39#define AB3100_TI3		0x5d
40#define AB3100_TI4		0x5e
41#define AB3100_TI5		0x5f
42
43/*
44 * RTC clock functions and device struct declaration
45 */
46static int ab3100_rtc_set_mmss(struct device *dev, time64_t secs)
47{
48	u8 regs[] = {AB3100_TI0, AB3100_TI1, AB3100_TI2,
49		     AB3100_TI3, AB3100_TI4, AB3100_TI5};
50	unsigned char buf[6];
51	u64 hw_counter = secs * AB3100_RTC_CLOCK_RATE * 2;
52	int err = 0;
53	int i;
54
55	buf[0] = (hw_counter) & 0xFF;
56	buf[1] = (hw_counter >> 8) & 0xFF;
57	buf[2] = (hw_counter >> 16) & 0xFF;
58	buf[3] = (hw_counter >> 24) & 0xFF;
59	buf[4] = (hw_counter >> 32) & 0xFF;
60	buf[5] = (hw_counter >> 40) & 0xFF;
61
62	for (i = 0; i < 6; i++) {
63		err = abx500_set_register_interruptible(dev, 0,
64							regs[i], buf[i]);
65		if (err)
66			return err;
67	}
68
69	/* Set the flag to mark that the clock is now set */
70	return abx500_mask_and_set_register_interruptible(dev, 0,
71							  AB3100_RTC,
72							  0x01, 0x01);
73
74}
75
76static int ab3100_rtc_read_time(struct device *dev, struct rtc_time *tm)
77{
78	time64_t time;
79	u8 rtcval;
80	int err;
81
82	err = abx500_get_register_interruptible(dev, 0,
83						AB3100_RTC, &rtcval);
84	if (err)
85		return err;
86
87	if (!(rtcval & 0x01)) {
88		dev_info(dev, "clock not set (lost power)");
89		return -EINVAL;
90	} else {
91		u64 hw_counter;
92		u8 buf[6];
93
94		/* Read out time registers */
95		err = abx500_get_register_page_interruptible(dev, 0,
96							     AB3100_TI0,
97							     buf, 6);
98		if (err != 0)
99			return err;
100
101		hw_counter = ((u64) buf[5] << 40) | ((u64) buf[4] << 32) |
102			((u64) buf[3] << 24) | ((u64) buf[2] << 16) |
103			((u64) buf[1] << 8) | (u64) buf[0];
104		time = hw_counter / (u64) (AB3100_RTC_CLOCK_RATE * 2);
105	}
106
107	rtc_time64_to_tm(time, tm);
108
109	return rtc_valid_tm(tm);
110}
111
112static int ab3100_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
113{
114	time64_t time;
115	u64 hw_counter;
116	u8 buf[6];
117	u8 rtcval;
118	int err;
119
120	/* Figure out if alarm is enabled or not */
121	err = abx500_get_register_interruptible(dev, 0,
122						AB3100_RTC, &rtcval);
123	if (err)
124		return err;
125	if (rtcval & 0x04)
126		alarm->enabled = 1;
127	else
128		alarm->enabled = 0;
129	/* No idea how this could be represented */
130	alarm->pending = 0;
131	/* Read out alarm registers, only 4 bytes */
132	err = abx500_get_register_page_interruptible(dev, 0,
133						     AB3100_AL0, buf, 4);
134	if (err)
135		return err;
136	hw_counter = ((u64) buf[3] << 40) | ((u64) buf[2] << 32) |
137		((u64) buf[1] << 24) | ((u64) buf[0] << 16);
138	time = hw_counter / (u64) (AB3100_RTC_CLOCK_RATE * 2);
139
140	rtc_time64_to_tm(time, &alarm->time);
141
142	return rtc_valid_tm(&alarm->time);
143}
144
145static int ab3100_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
146{
147	u8 regs[] = {AB3100_AL0, AB3100_AL1, AB3100_AL2, AB3100_AL3};
148	unsigned char buf[4];
149	time64_t secs;
150	u64 hw_counter;
151	int err;
152	int i;
153
154	secs = rtc_tm_to_time64(&alarm->time);
155	hw_counter = secs * AB3100_RTC_CLOCK_RATE * 2;
156	buf[0] = (hw_counter >> 16) & 0xFF;
157	buf[1] = (hw_counter >> 24) & 0xFF;
158	buf[2] = (hw_counter >> 32) & 0xFF;
159	buf[3] = (hw_counter >> 40) & 0xFF;
160
161	/* Set the alarm */
162	for (i = 0; i < 4; i++) {
163		err = abx500_set_register_interruptible(dev, 0,
164							regs[i], buf[i]);
165		if (err)
166			return err;
167	}
168	/* Then enable the alarm */
169	return abx500_mask_and_set_register_interruptible(dev, 0,
170							  AB3100_RTC, (1 << 2),
171							  alarm->enabled << 2);
172}
173
174static int ab3100_rtc_irq_enable(struct device *dev, unsigned int enabled)
175{
176	/*
177	 * It's not possible to enable/disable the alarm IRQ for this RTC.
178	 * It does not actually trigger any IRQ: instead its only function is
179	 * to power up the system, if it wasn't on. This will manifest as
180	 * a "power up cause" in the AB3100 power driver (battery charging etc)
181	 * and need to be handled there instead.
182	 */
183	if (enabled)
184		return abx500_mask_and_set_register_interruptible(dev, 0,
185						    AB3100_RTC, (1 << 2),
186						    1 << 2);
187	else
188		return abx500_mask_and_set_register_interruptible(dev, 0,
189						    AB3100_RTC, (1 << 2),
190						    0);
191}
192
193static const struct rtc_class_ops ab3100_rtc_ops = {
194	.read_time	= ab3100_rtc_read_time,
195	.set_mmss64	= ab3100_rtc_set_mmss,
196	.read_alarm	= ab3100_rtc_read_alarm,
197	.set_alarm	= ab3100_rtc_set_alarm,
198	.alarm_irq_enable = ab3100_rtc_irq_enable,
199};
200
201static int __init ab3100_rtc_probe(struct platform_device *pdev)
202{
203	int err;
204	u8 regval;
205	struct rtc_device *rtc;
206
207	/* The first RTC register needs special treatment */
208	err = abx500_get_register_interruptible(&pdev->dev, 0,
209						AB3100_RTC, &regval);
210	if (err) {
211		dev_err(&pdev->dev, "unable to read RTC register\n");
212		return -ENODEV;
213	}
214
215	if ((regval & 0xFE) != RTC_SETTING) {
216		dev_warn(&pdev->dev, "not default value in RTC reg 0x%x\n",
217			 regval);
218	}
219
220	if ((regval & 1) == 0) {
221		/*
222		 * Set bit to detect power loss.
223		 * This bit remains until RTC power is lost.
224		 */
225		regval = 1 | RTC_SETTING;
226		err = abx500_set_register_interruptible(&pdev->dev, 0,
227							AB3100_RTC, regval);
228		/* Ignore any error on this write */
229	}
230
231	rtc = devm_rtc_device_register(&pdev->dev, "ab3100-rtc",
232					&ab3100_rtc_ops, THIS_MODULE);
233	if (IS_ERR(rtc)) {
234		err = PTR_ERR(rtc);
235		return err;
236	}
237	platform_set_drvdata(pdev, rtc);
238
239	return 0;
240}
241
242static struct platform_driver ab3100_rtc_driver = {
243	.driver = {
244		.name = "ab3100-rtc",
245	},
246};
247
248module_platform_driver_probe(ab3100_rtc_driver, ab3100_rtc_probe);
249
250MODULE_AUTHOR("Linus Walleij <linus.walleij@stericsson.com>");
251MODULE_DESCRIPTION("AB3100 RTC Driver");
252MODULE_LICENSE("GPL");
253