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Linux/drivers/rtc/rtc-ab3100.c

  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  */
 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 
 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 
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 
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 
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 
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, &regval);
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 = devm_rtc_device_register(&pdev->dev, "ab3100-rtc",
233                                         &ab3100_rtc_ops, 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 
243 static struct platform_driver ab3100_rtc_driver = {
244         .driver = {
245                 .name = "ab3100-rtc",
246                 .owner = THIS_MODULE,
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 

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