1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright (C) 2007-2009 ST-Ericsson AB
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 */
ab3100_rtc_set_time(struct device * dev,struct rtc_time * tm)46 static int ab3100_rtc_set_time(struct device *dev, struct rtc_time *tm)
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 = rtc_tm_to_time64(tm) * 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
ab3100_rtc_read_time(struct device * dev,struct rtc_time * tm)76 static 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 0;
110 }
111
ab3100_rtc_read_alarm(struct device * dev,struct rtc_wkalrm * alarm)112 static 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
ab3100_rtc_set_alarm(struct device * dev,struct rtc_wkalrm * alarm)145 static 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
ab3100_rtc_irq_enable(struct device * dev,unsigned int enabled)174 static 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
193 static const struct rtc_class_ops ab3100_rtc_ops = {
194 .read_time = ab3100_rtc_read_time,
195 .set_time = ab3100_rtc_set_time,
196 .read_alarm = ab3100_rtc_read_alarm,
197 .set_alarm = ab3100_rtc_set_alarm,
198 .alarm_irq_enable = ab3100_rtc_irq_enable,
199 };
200
ab3100_rtc_probe(struct platform_device * pdev)201 static 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, ®val);
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_allocate_device(&pdev->dev);
232 if (IS_ERR(rtc))
233 return PTR_ERR(rtc);
234
235 rtc->ops = &ab3100_rtc_ops;
236 /* 48bit counter at (AB3100_RTC_CLOCK_RATE * 2) */
237 rtc->range_max = U32_MAX;
238
239 platform_set_drvdata(pdev, rtc);
240
241 return rtc_register_device(rtc);
242 }
243
244 static struct platform_driver ab3100_rtc_driver = {
245 .driver = {
246 .name = "ab3100-rtc",
247 },
248 };
249
250 module_platform_driver_probe(ab3100_rtc_driver, ab3100_rtc_probe);
251
252 MODULE_AUTHOR("Linus Walleij <linus.walleij@stericsson.com>");
253 MODULE_DESCRIPTION("AB3100 RTC Driver");
254 MODULE_LICENSE("GPL");
255