aboutsummaryrefslogtreecommitdiff
path: root/drivers/rtc/rtc-ab3100.c
blob: 821ff52a2222e03f02c7ecc34e8d1bc6de5d18b0 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
/*
 * Copyright (C) 2007-2009 ST-Ericsson AB
 * License terms: GNU General Public License (GPL) version 2
 * RTC clock driver for the AB3100 Analog Baseband Chip
 * Author: Linus Walleij <linus.walleij@stericsson.com>
 */
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/platform_device.h>
#include <linux/rtc.h>
#include <linux/mfd/abx500.h>

/* Clock rate in Hz */
#define AB3100_RTC_CLOCK_RATE	32768

/*
 * The AB3100 RTC registers. These are the same for
 * AB3000 and AB3100.
 * Control register:
 * Bit 0: RTC Monitor cleared=0, active=1, if you set it
 *        to 1 it remains active until RTC power is lost.
 * Bit 1: 32 kHz Oscillator, 0 = on, 1 = bypass
 * Bit 2: Alarm on, 0 = off, 1 = on
 * Bit 3: 32 kHz buffer disabling, 0 = enabled, 1 = disabled
 */
#define AB3100_RTC		0x53
/* default setting, buffer disabled, alarm on */
#define RTC_SETTING		0x30
/* Alarm when AL0-AL3 == TI0-TI3  */
#define AB3100_AL0		0x56
#define AB3100_AL1		0x57
#define AB3100_AL2		0x58
#define AB3100_AL3		0x59
/* This 48-bit register that counts up at 32768 Hz */
#define AB3100_TI0		0x5a
#define AB3100_TI1		0x5b
#define AB3100_TI2		0x5c
#define AB3100_TI3		0x5d
#define AB3100_TI4		0x5e
#define AB3100_TI5		0x5f

/*
 * RTC clock functions and device struct declaration
 */
static int ab3100_rtc_set_mmss(struct device *dev, time64_t secs)
{
	u8 regs[] = {AB3100_TI0, AB3100_TI1, AB3100_TI2,
		     AB3100_TI3, AB3100_TI4, AB3100_TI5};
	unsigned char buf[6];
	u64 hw_counter = secs * AB3100_RTC_CLOCK_RATE * 2;
	int err = 0;
	int i;

	buf[0] = (hw_counter) & 0xFF;
	buf[1] = (hw_counter >> 8) & 0xFF;
	buf[2] = (hw_counter >> 16) & 0xFF;
	buf[3] = (hw_counter >> 24) & 0xFF;
	buf[4] = (hw_counter >> 32) & 0xFF;
	buf[5] = (hw_counter >> 40) & 0xFF;

	for (i = 0; i < 6; i++) {
		err = abx500_set_register_interruptible(dev, 0,
							regs[i], buf[i]);
		if (err)
			return err;
	}

	/* Set the flag to mark that the clock is now set */
	return abx500_mask_and_set_register_interruptible(dev, 0,
							  AB3100_RTC,
							  0x01, 0x01);

}

static int ab3100_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
	time64_t time;
	u8 rtcval;
	int err;

	err = abx500_get_register_interruptible(dev, 0,
						AB3100_RTC, &rtcval);
	if (err)
		return err;

	if (!(rtcval & 0x01)) {
		dev_info(dev, "clock not set (lost power)");
		return -EINVAL;
	} else {
		u64 hw_counter;
		u8 buf[6];

		/* Read out time registers */
		err = abx500_get_register_page_interruptible(dev, 0,
							     AB3100_TI0,
							     buf, 6);
		if (err != 0)
			return err;

		hw_counter = ((u64) buf[5] << 40) | ((u64) buf[4] << 32) |
			((u64) buf[3] << 24) | ((u64) buf[2] << 16) |
			((u64) buf[1] << 8) | (u64) buf[0];
		time = hw_counter / (u64) (AB3100_RTC_CLOCK_RATE * 2);
	}

	rtc_time64_to_tm(time, tm);

	return 0;
}

static int ab3100_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
{
	time64_t time;
	u64 hw_counter;
	u8 buf[6];
	u8 rtcval;
	int err;

	/* Figure out if alarm is enabled or not */
	err = abx500_get_register_interruptible(dev, 0,
						AB3100_RTC, &rtcval);
	if (err)
		return err;
	if (rtcval & 0x04)
		alarm->enabled = 1;
	else
		alarm->enabled = 0;
	/* No idea how this could be represented */
	alarm->pending = 0;
	/* Read out alarm registers, only 4 bytes */
	err = abx500_get_register_page_interruptible(dev, 0,
						     AB3100_AL0, buf, 4);
	if (err)
		return err;
	hw_counter = ((u64) buf[3] << 40) | ((u64) buf[2] << 32) |
		((u64) buf[1] << 24) | ((u64) buf[0] << 16);
	time = hw_counter / (u64) (AB3100_RTC_CLOCK_RATE * 2);

	rtc_time64_to_tm(time, &alarm->time);

	return rtc_valid_tm(&alarm->time);
}

static int ab3100_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
{
	u8 regs[] = {AB3100_AL0, AB3100_AL1, AB3100_AL2, AB3100_AL3};
	unsigned char buf[4];
	time64_t secs;
	u64 hw_counter;
	int err;
	int i;

	secs = rtc_tm_to_time64(&alarm->time);
	hw_counter = secs * AB3100_RTC_CLOCK_RATE * 2;
	buf[0] = (hw_counter >> 16) & 0xFF;
	buf[1] = (hw_counter >> 24) & 0xFF;
	buf[2] = (hw_counter >> 32) & 0xFF;
	buf[3] = (hw_counter >> 40) & 0xFF;

	/* Set the alarm */
	for (i = 0; i < 4; i++) {
		err = abx500_set_register_interruptible(dev, 0,
							regs[i], buf[i]);
		if (err)
			return err;
	}
	/* Then enable the alarm */
	return abx500_mask_and_set_register_interruptible(dev, 0,
							  AB3100_RTC, (1 << 2),
							  alarm->enabled << 2);
}

static int ab3100_rtc_irq_enable(struct device *dev, unsigned int enabled)
{
	/*
	 * It's not possible to enable/disable the alarm IRQ for this RTC.
	 * It does not actually trigger any IRQ: instead its only function is
	 * to power up the system, if it wasn't on. This will manifest as
	 * a "power up cause" in the AB3100 power driver (battery charging etc)
	 * and need to be handled there instead.
	 */
	if (enabled)
		return abx500_mask_and_set_register_interruptible(dev, 0,
						    AB3100_RTC, (1 << 2),
						    1 << 2);
	else
		return abx500_mask_and_set_register_interruptible(dev, 0,
						    AB3100_RTC, (1 << 2),
						    0);
}

static const struct rtc_class_ops ab3100_rtc_ops = {
	.read_time	= ab3100_rtc_read_time,
	.set_mmss64	= ab3100_rtc_set_mmss,
	.read_alarm	= ab3100_rtc_read_alarm,
	.set_alarm	= ab3100_rtc_set_alarm,
	.alarm_irq_enable = ab3100_rtc_irq_enable,
};

static int __init ab3100_rtc_probe(struct platform_device *pdev)
{
	int err;
	u8 regval;
	struct rtc_device *rtc;

	/* The first RTC register needs special treatment */
	err = abx500_get_register_interruptible(&pdev->dev, 0,
						AB3100_RTC, &regval);
	if (err) {
		dev_err(&pdev->dev, "unable to read RTC register\n");
		return -ENODEV;
	}

	if ((regval & 0xFE) != RTC_SETTING) {
		dev_warn(&pdev->dev, "not default value in RTC reg 0x%x\n",
			 regval);
	}

	if ((regval & 1) == 0) {
		/*
		 * Set bit to detect power loss.
		 * This bit remains until RTC power is lost.
		 */
		regval = 1 | RTC_SETTING;
		err = abx500_set_register_interruptible(&pdev->dev, 0,
							AB3100_RTC, regval);
		/* Ignore any error on this write */
	}

	rtc = devm_rtc_device_register(&pdev->dev, "ab3100-rtc",
					&ab3100_rtc_ops, THIS_MODULE);
	if (IS_ERR(rtc)) {
		err = PTR_ERR(rtc);
		return err;
	}
	platform_set_drvdata(pdev, rtc);

	return 0;
}

static struct platform_driver ab3100_rtc_driver = {
	.driver = {
		.name = "ab3100-rtc",
	},
};

module_platform_driver_probe(ab3100_rtc_driver, ab3100_rtc_probe);

MODULE_AUTHOR("Linus Walleij <linus.walleij@stericsson.com>");
MODULE_DESCRIPTION("AB3100 RTC Driver");
MODULE_LICENSE("GPL");