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Linux/drivers/rtc/rtc-isl12057.c

  1 /*
  2  * rtc-isl12057 - Driver for Intersil ISL12057 I2C Real Time Clock
  3  *
  4  * Copyright (C) 2013, Arnaud EBALARD <arno@natisbad.org>
  5  *
  6  * This work is largely based on Intersil ISL1208 driver developed by
  7  * Hebert Valerio Riedel <hvr@gnu.org>.
  8  *
  9  * Detailed datasheet on which this development is based is available here:
 10  *
 11  *  http://natisbad.org/NAS2/refs/ISL12057.pdf
 12  *
 13  * This program is free software; you can redistribute it and/or modify
 14  * it under the terms of the GNU General Public License as published by
 15  * the Free Software Foundation; either version 2 of the License, or
 16  * (at your option) any later version.
 17  *
 18  * This program is distributed in the hope that it will be useful,
 19  * but WITHOUT ANY WARRANTY; without even the implied warranty of
 20  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 21  * GNU General Public License for more details.
 22  */
 23 
 24 #include <linux/module.h>
 25 #include <linux/mutex.h>
 26 #include <linux/rtc.h>
 27 #include <linux/i2c.h>
 28 #include <linux/bcd.h>
 29 #include <linux/of.h>
 30 #include <linux/of_device.h>
 31 #include <linux/regmap.h>
 32 
 33 #define DRV_NAME "rtc-isl12057"
 34 
 35 /* RTC section */
 36 #define ISL12057_REG_RTC_SC     0x00    /* Seconds */
 37 #define ISL12057_REG_RTC_MN     0x01    /* Minutes */
 38 #define ISL12057_REG_RTC_HR     0x02    /* Hours */
 39 #define ISL12057_REG_RTC_HR_PM  BIT(5)  /* AM/PM bit in 12h format */
 40 #define ISL12057_REG_RTC_HR_MIL BIT(6)  /* 24h/12h format */
 41 #define ISL12057_REG_RTC_DW     0x03    /* Day of the Week */
 42 #define ISL12057_REG_RTC_DT     0x04    /* Date */
 43 #define ISL12057_REG_RTC_MO     0x05    /* Month */
 44 #define ISL12057_REG_RTC_YR     0x06    /* Year */
 45 #define ISL12057_RTC_SEC_LEN    7
 46 
 47 /* Alarm 1 section */
 48 #define ISL12057_REG_A1_SC      0x07    /* Alarm 1 Seconds */
 49 #define ISL12057_REG_A1_MN      0x08    /* Alarm 1 Minutes */
 50 #define ISL12057_REG_A1_HR      0x09    /* Alarm 1 Hours */
 51 #define ISL12057_REG_A1_HR_PM   BIT(5)  /* AM/PM bit in 12h format */
 52 #define ISL12057_REG_A1_HR_MIL  BIT(6)  /* 24h/12h format */
 53 #define ISL12057_REG_A1_DWDT    0x0A    /* Alarm 1 Date / Day of the week */
 54 #define ISL12057_REG_A1_DWDT_B  BIT(6)  /* DW / DT selection bit */
 55 #define ISL12057_A1_SEC_LEN     4
 56 
 57 /* Alarm 2 section */
 58 #define ISL12057_REG_A2_MN      0x0B    /* Alarm 2 Minutes */
 59 #define ISL12057_REG_A2_HR      0x0C    /* Alarm 2 Hours */
 60 #define ISL12057_REG_A2_DWDT    0x0D    /* Alarm 2 Date / Day of the week */
 61 #define ISL12057_A2_SEC_LEN     3
 62 
 63 /* Control/Status registers */
 64 #define ISL12057_REG_INT        0x0E
 65 #define ISL12057_REG_INT_A1IE   BIT(0)  /* Alarm 1 interrupt enable bit */
 66 #define ISL12057_REG_INT_A2IE   BIT(1)  /* Alarm 2 interrupt enable bit */
 67 #define ISL12057_REG_INT_INTCN  BIT(2)  /* Interrupt control enable bit */
 68 #define ISL12057_REG_INT_RS1    BIT(3)  /* Freq out control bit 1 */
 69 #define ISL12057_REG_INT_RS2    BIT(4)  /* Freq out control bit 2 */
 70 #define ISL12057_REG_INT_EOSC   BIT(7)  /* Oscillator enable bit */
 71 
 72 #define ISL12057_REG_SR         0x0F
 73 #define ISL12057_REG_SR_A1F     BIT(0)  /* Alarm 1 interrupt bit */
 74 #define ISL12057_REG_SR_A2F     BIT(1)  /* Alarm 2 interrupt bit */
 75 #define ISL12057_REG_SR_OSF     BIT(7)  /* Oscillator failure bit */
 76 
 77 /* Register memory map length */
 78 #define ISL12057_MEM_MAP_LEN    0x10
 79 
 80 struct isl12057_rtc_data {
 81         struct regmap *regmap;
 82         struct mutex lock;
 83 };
 84 
 85 static void isl12057_rtc_regs_to_tm(struct rtc_time *tm, u8 *regs)
 86 {
 87         tm->tm_sec = bcd2bin(regs[ISL12057_REG_RTC_SC]);
 88         tm->tm_min = bcd2bin(regs[ISL12057_REG_RTC_MN]);
 89 
 90         if (regs[ISL12057_REG_RTC_HR] & ISL12057_REG_RTC_HR_MIL) { /* AM/PM */
 91                 tm->tm_hour = bcd2bin(regs[ISL12057_REG_RTC_HR] & 0x0f);
 92                 if (regs[ISL12057_REG_RTC_HR] & ISL12057_REG_RTC_HR_PM)
 93                         tm->tm_hour += 12;
 94         } else {                                            /* 24 hour mode */
 95                 tm->tm_hour = bcd2bin(regs[ISL12057_REG_RTC_HR] & 0x3f);
 96         }
 97 
 98         tm->tm_mday = bcd2bin(regs[ISL12057_REG_RTC_DT]);
 99         tm->tm_wday = bcd2bin(regs[ISL12057_REG_RTC_DW]) - 1; /* starts at 1 */
100         tm->tm_mon  = bcd2bin(regs[ISL12057_REG_RTC_MO]) - 1; /* starts at 1 */
101         tm->tm_year = bcd2bin(regs[ISL12057_REG_RTC_YR]) + 100;
102 }
103 
104 static int isl12057_rtc_tm_to_regs(u8 *regs, struct rtc_time *tm)
105 {
106         /*
107          * The clock has an 8 bit wide bcd-coded register for the year.
108          * tm_year is an offset from 1900 and we are interested in the
109          * 2000-2099 range, so any value less than 100 is invalid.
110          */
111         if (tm->tm_year < 100)
112                 return -EINVAL;
113 
114         regs[ISL12057_REG_RTC_SC] = bin2bcd(tm->tm_sec);
115         regs[ISL12057_REG_RTC_MN] = bin2bcd(tm->tm_min);
116         regs[ISL12057_REG_RTC_HR] = bin2bcd(tm->tm_hour); /* 24-hour format */
117         regs[ISL12057_REG_RTC_DT] = bin2bcd(tm->tm_mday);
118         regs[ISL12057_REG_RTC_MO] = bin2bcd(tm->tm_mon + 1);
119         regs[ISL12057_REG_RTC_YR] = bin2bcd(tm->tm_year - 100);
120         regs[ISL12057_REG_RTC_DW] = bin2bcd(tm->tm_wday + 1);
121 
122         return 0;
123 }
124 
125 /*
126  * Try and match register bits w/ fixed null values to see whether we
127  * are dealing with an ISL12057. Note: this function is called early
128  * during init and hence does need mutex protection.
129  */
130 static int isl12057_i2c_validate_chip(struct regmap *regmap)
131 {
132         u8 regs[ISL12057_MEM_MAP_LEN];
133         static const u8 mask[ISL12057_MEM_MAP_LEN] = { 0x80, 0x80, 0x80, 0xf8,
134                                                        0xc0, 0x60, 0x00, 0x00,
135                                                        0x00, 0x00, 0x00, 0x00,
136                                                        0x00, 0x00, 0x60, 0x7c };
137         int ret, i;
138 
139         ret = regmap_bulk_read(regmap, 0, regs, ISL12057_MEM_MAP_LEN);
140         if (ret)
141                 return ret;
142 
143         for (i = 0; i < ISL12057_MEM_MAP_LEN; ++i) {
144                 if (regs[i] & mask[i])  /* check if bits are cleared */
145                         return -ENODEV;
146         }
147 
148         return 0;
149 }
150 
151 static int isl12057_rtc_read_time(struct device *dev, struct rtc_time *tm)
152 {
153         struct isl12057_rtc_data *data = dev_get_drvdata(dev);
154         u8 regs[ISL12057_RTC_SEC_LEN];
155         int ret;
156 
157         mutex_lock(&data->lock);
158         ret = regmap_bulk_read(data->regmap, ISL12057_REG_RTC_SC, regs,
159                                ISL12057_RTC_SEC_LEN);
160         mutex_unlock(&data->lock);
161 
162         if (ret) {
163                 dev_err(dev, "%s: RTC read failed\n", __func__);
164                 return ret;
165         }
166 
167         isl12057_rtc_regs_to_tm(tm, regs);
168 
169         return rtc_valid_tm(tm);
170 }
171 
172 static int isl12057_rtc_set_time(struct device *dev, struct rtc_time *tm)
173 {
174         struct isl12057_rtc_data *data = dev_get_drvdata(dev);
175         u8 regs[ISL12057_RTC_SEC_LEN];
176         int ret;
177 
178         ret = isl12057_rtc_tm_to_regs(regs, tm);
179         if (ret)
180                 return ret;
181 
182         mutex_lock(&data->lock);
183         ret = regmap_bulk_write(data->regmap, ISL12057_REG_RTC_SC, regs,
184                                 ISL12057_RTC_SEC_LEN);
185         mutex_unlock(&data->lock);
186 
187         if (ret)
188                 dev_err(dev, "%s: RTC write failed\n", __func__);
189 
190         return ret;
191 }
192 
193 /*
194  * Check current RTC status and enable/disable what needs to be. Return 0 if
195  * everything went ok and a negative value upon error. Note: this function
196  * is called early during init and hence does need mutex protection.
197  */
198 static int isl12057_check_rtc_status(struct device *dev, struct regmap *regmap)
199 {
200         int ret;
201 
202         /* Enable oscillator if not already running */
203         ret = regmap_update_bits(regmap, ISL12057_REG_INT,
204                                  ISL12057_REG_INT_EOSC, 0);
205         if (ret < 0) {
206                 dev_err(dev, "Unable to enable oscillator\n");
207                 return ret;
208         }
209 
210         /* Clear oscillator failure bit if needed */
211         ret = regmap_update_bits(regmap, ISL12057_REG_SR,
212                                  ISL12057_REG_SR_OSF, 0);
213         if (ret < 0) {
214                 dev_err(dev, "Unable to clear oscillator failure bit\n");
215                 return ret;
216         }
217 
218         /* Clear alarm bit if needed */
219         ret = regmap_update_bits(regmap, ISL12057_REG_SR,
220                                  ISL12057_REG_SR_A1F, 0);
221         if (ret < 0) {
222                 dev_err(dev, "Unable to clear alarm bit\n");
223                 return ret;
224         }
225 
226         return 0;
227 }
228 
229 static const struct rtc_class_ops rtc_ops = {
230         .read_time = isl12057_rtc_read_time,
231         .set_time = isl12057_rtc_set_time,
232 };
233 
234 static struct regmap_config isl12057_rtc_regmap_config = {
235         .reg_bits = 8,
236         .val_bits = 8,
237 };
238 
239 static int isl12057_probe(struct i2c_client *client,
240                           const struct i2c_device_id *id)
241 {
242         struct device *dev = &client->dev;
243         struct isl12057_rtc_data *data;
244         struct rtc_device *rtc;
245         struct regmap *regmap;
246         int ret;
247 
248         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C |
249                                      I2C_FUNC_SMBUS_BYTE_DATA |
250                                      I2C_FUNC_SMBUS_I2C_BLOCK))
251                 return -ENODEV;
252 
253         regmap = devm_regmap_init_i2c(client, &isl12057_rtc_regmap_config);
254         if (IS_ERR(regmap)) {
255                 ret = PTR_ERR(regmap);
256                 dev_err(dev, "regmap allocation failed: %d\n", ret);
257                 return ret;
258         }
259 
260         ret = isl12057_i2c_validate_chip(regmap);
261         if (ret)
262                 return ret;
263 
264         ret = isl12057_check_rtc_status(dev, regmap);
265         if (ret)
266                 return ret;
267 
268         data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
269         if (!data)
270                 return -ENOMEM;
271 
272         mutex_init(&data->lock);
273         data->regmap = regmap;
274         dev_set_drvdata(dev, data);
275 
276         rtc = devm_rtc_device_register(dev, DRV_NAME, &rtc_ops, THIS_MODULE);
277         return PTR_ERR_OR_ZERO(rtc);
278 }
279 
280 #ifdef CONFIG_OF
281 static const struct of_device_id isl12057_dt_match[] = {
282         { .compatible = "isl,isl12057" },
283         { },
284 };
285 #endif
286 
287 static const struct i2c_device_id isl12057_id[] = {
288         { "isl12057", 0 },
289         { }
290 };
291 MODULE_DEVICE_TABLE(i2c, isl12057_id);
292 
293 static struct i2c_driver isl12057_driver = {
294         .driver = {
295                 .name = DRV_NAME,
296                 .owner = THIS_MODULE,
297                 .of_match_table = of_match_ptr(isl12057_dt_match),
298         },
299         .probe    = isl12057_probe,
300         .id_table = isl12057_id,
301 };
302 module_i2c_driver(isl12057_driver);
303 
304 MODULE_AUTHOR("Arnaud EBALARD <arno@natisbad.org>");
305 MODULE_DESCRIPTION("Intersil ISL12057 RTC driver");
306 MODULE_LICENSE("GPL");
307 

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