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 */
ab3100_rtc_set_mmss(struct device * dev,unsigned long secs)46 static int ab3100_rtc_set_mmss(struct device *dev, unsigned long 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 fat_time = (u64) secs * AB3100_RTC_CLOCK_RATE * 2;
52 int err = 0;
53 int i;
54
55 buf[0] = (fat_time) & 0xFF;
56 buf[1] = (fat_time >> 8) & 0xFF;
57 buf[2] = (fat_time >> 16) & 0xFF;
58 buf[3] = (fat_time >> 24) & 0xFF;
59 buf[4] = (fat_time >> 32) & 0xFF;
60 buf[5] = (fat_time >> 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 unsigned long 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 fat_time;
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 fat_time = ((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 = (unsigned long) (fat_time /
105 (u64) (AB3100_RTC_CLOCK_RATE * 2));
106 }
107
108 rtc_time_to_tm(time, tm);
109
110 return rtc_valid_tm(tm);
111 }
112
ab3100_rtc_read_alarm(struct device * dev,struct rtc_wkalrm * alarm)113 static int ab3100_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
114 {
115 unsigned long time;
116 u64 fat_time;
117 u8 buf[6];
118 u8 rtcval;
119 int err;
120
121 /* Figure out if alarm is enabled or not */
122 err = abx500_get_register_interruptible(dev, 0,
123 AB3100_RTC, &rtcval);
124 if (err)
125 return err;
126 if (rtcval & 0x04)
127 alarm->enabled = 1;
128 else
129 alarm->enabled = 0;
130 /* No idea how this could be represented */
131 alarm->pending = 0;
132 /* Read out alarm registers, only 4 bytes */
133 err = abx500_get_register_page_interruptible(dev, 0,
134 AB3100_AL0, buf, 4);
135 if (err)
136 return err;
137 fat_time = ((u64) buf[3] << 40) | ((u64) buf[2] << 32) |
138 ((u64) buf[1] << 24) | ((u64) buf[0] << 16);
139 time = (unsigned long) (fat_time / (u64) (AB3100_RTC_CLOCK_RATE * 2));
140
141 rtc_time_to_tm(time, &alarm->time);
142
143 return rtc_valid_tm(&alarm->time);
144 }
145
ab3100_rtc_set_alarm(struct device * dev,struct rtc_wkalrm * alarm)146 static int ab3100_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
147 {
148 u8 regs[] = {AB3100_AL0, AB3100_AL1, AB3100_AL2, AB3100_AL3};
149 unsigned char buf[4];
150 unsigned long secs;
151 u64 fat_time;
152 int err;
153 int i;
154
155 rtc_tm_to_time(&alarm->time, &secs);
156 fat_time = (u64) secs * AB3100_RTC_CLOCK_RATE * 2;
157 buf[0] = (fat_time >> 16) & 0xFF;
158 buf[1] = (fat_time >> 24) & 0xFF;
159 buf[2] = (fat_time >> 32) & 0xFF;
160 buf[3] = (fat_time >> 40) & 0xFF;
161
162 /* Set the alarm */
163 for (i = 0; i < 4; i++) {
164 err = abx500_set_register_interruptible(dev, 0,
165 regs[i], buf[i]);
166 if (err)
167 return err;
168 }
169 /* Then enable the alarm */
170 return abx500_mask_and_set_register_interruptible(dev, 0,
171 AB3100_RTC, (1 << 2),
172 alarm->enabled << 2);
173 }
174
ab3100_rtc_irq_enable(struct device * dev,unsigned int enabled)175 static int ab3100_rtc_irq_enable(struct device *dev, unsigned int enabled)
176 {
177 /*
178 * It's not possible to enable/disable the alarm IRQ for this RTC.
179 * It does not actually trigger any IRQ: instead its only function is
180 * to power up the system, if it wasn't on. This will manifest as
181 * a "power up cause" in the AB3100 power driver (battery charging etc)
182 * and need to be handled there instead.
183 */
184 if (enabled)
185 return abx500_mask_and_set_register_interruptible(dev, 0,
186 AB3100_RTC, (1 << 2),
187 1 << 2);
188 else
189 return abx500_mask_and_set_register_interruptible(dev, 0,
190 AB3100_RTC, (1 << 2),
191 0);
192 }
193
194 static const struct rtc_class_ops ab3100_rtc_ops = {
195 .read_time = ab3100_rtc_read_time,
196 .set_mmss = ab3100_rtc_set_mmss,
197 .read_alarm = ab3100_rtc_read_alarm,
198 .set_alarm = ab3100_rtc_set_alarm,
199 .alarm_irq_enable = ab3100_rtc_irq_enable,
200 };
201
ab3100_rtc_probe(struct platform_device * pdev)202 static int __init ab3100_rtc_probe(struct platform_device *pdev)
203 {
204 int err;
205 u8 regval;
206 struct rtc_device *rtc;
207
208 /* The first RTC register needs special treatment */
209 err = abx500_get_register_interruptible(&pdev->dev, 0,
210 AB3100_RTC, ®val);
211 if (err) {
212 dev_err(&pdev->dev, "unable to read RTC register\n");
213 return -ENODEV;
214 }
215
216 if ((regval & 0xFE) != RTC_SETTING) {
217 dev_warn(&pdev->dev, "not default value in RTC reg 0x%x\n",
218 regval);
219 }
220
221 if ((regval & 1) == 0) {
222 /*
223 * Set bit to detect power loss.
224 * This bit remains until RTC power is lost.
225 */
226 regval = 1 | RTC_SETTING;
227 err = abx500_set_register_interruptible(&pdev->dev, 0,
228 AB3100_RTC, regval);
229 /* Ignore any error on this write */
230 }
231
232 rtc = rtc_device_register("ab3100-rtc", &pdev->dev, &ab3100_rtc_ops,
233 THIS_MODULE);
234 if (IS_ERR(rtc)) {
235 err = PTR_ERR(rtc);
236 return err;
237 }
238 platform_set_drvdata(pdev, rtc);
239
240 return 0;
241 }
242
ab3100_rtc_remove(struct platform_device * pdev)243 static int __exit ab3100_rtc_remove(struct platform_device *pdev)
244 {
245 struct rtc_device *rtc = platform_get_drvdata(pdev);
246
247 rtc_device_unregister(rtc);
248 platform_set_drvdata(pdev, NULL);
249 return 0;
250 }
251
252 static struct platform_driver ab3100_rtc_driver = {
253 .driver = {
254 .name = "ab3100-rtc",
255 .owner = THIS_MODULE,
256 },
257 .remove = __exit_p(ab3100_rtc_remove),
258 };
259
ab3100_rtc_init(void)260 static int __init ab3100_rtc_init(void)
261 {
262 return platform_driver_probe(&ab3100_rtc_driver,
263 ab3100_rtc_probe);
264 }
265
ab3100_rtc_exit(void)266 static void __exit ab3100_rtc_exit(void)
267 {
268 platform_driver_unregister(&ab3100_rtc_driver);
269 }
270
271 module_init(ab3100_rtc_init);
272 module_exit(ab3100_rtc_exit);
273
274 MODULE_AUTHOR("Linus Walleij <linus.walleij@stericsson.com>");
275 MODULE_DESCRIPTION("AB3100 RTC Driver");
276 MODULE_LICENSE("GPL");
277