1 /* 2 * ST M48T86 / Dallas DS12887 RTC driver 3 * Copyright (c) 2006 Tower Technologies 4 * 5 * Author: Alessandro Zummo <a.zummo@towertech.it> 6 * 7 * This program is free software; you can redistribute it and/or modify 8 * it under the terms of the GNU General Public License version 2 as 9 * published by the Free Software Foundation. 10 * 11 * This drivers only supports the clock running in BCD and 24H mode. 12 * If it will be ever adapted to binary and 12H mode, care must be taken 13 * to not introduce bugs. 14 */ 15 16 #include <linux/module.h> 17 #include <linux/rtc.h> 18 #include <linux/platform_device.h> 19 #include <linux/bcd.h> 20 #include <linux/io.h> 21 22 #define M48T86_SEC 0x00 23 #define M48T86_SECALRM 0x01 24 #define M48T86_MIN 0x02 25 #define M48T86_MINALRM 0x03 26 #define M48T86_HOUR 0x04 27 #define M48T86_HOURALRM 0x05 28 #define M48T86_DOW 0x06 /* 1 = sunday */ 29 #define M48T86_DOM 0x07 30 #define M48T86_MONTH 0x08 /* 1 - 12 */ 31 #define M48T86_YEAR 0x09 /* 0 - 99 */ 32 #define M48T86_A 0x0a 33 #define M48T86_B 0x0b 34 #define M48T86_B_SET BIT(7) 35 #define M48T86_B_DM BIT(2) 36 #define M48T86_B_H24 BIT(1) 37 #define M48T86_C 0x0c 38 #define M48T86_D 0x0d 39 #define M48T86_D_VRT BIT(7) 40 #define M48T86_NVRAM(x) (0x0e + (x)) 41 #define M48T86_NVRAM_LEN 114 42 43 struct m48t86_rtc_info { 44 void __iomem *index_reg; 45 void __iomem *data_reg; 46 struct rtc_device *rtc; 47 }; 48 49 static unsigned char m48t86_readb(struct device *dev, unsigned long addr) 50 { 51 struct m48t86_rtc_info *info = dev_get_drvdata(dev); 52 unsigned char value; 53 54 writeb(addr, info->index_reg); 55 value = readb(info->data_reg); 56 57 return value; 58 } 59 60 static void m48t86_writeb(struct device *dev, 61 unsigned char value, unsigned long addr) 62 { 63 struct m48t86_rtc_info *info = dev_get_drvdata(dev); 64 65 writeb(addr, info->index_reg); 66 writeb(value, info->data_reg); 67 } 68 69 static int m48t86_rtc_read_time(struct device *dev, struct rtc_time *tm) 70 { 71 unsigned char reg; 72 73 reg = m48t86_readb(dev, M48T86_B); 74 75 if (reg & M48T86_B_DM) { 76 /* data (binary) mode */ 77 tm->tm_sec = m48t86_readb(dev, M48T86_SEC); 78 tm->tm_min = m48t86_readb(dev, M48T86_MIN); 79 tm->tm_hour = m48t86_readb(dev, M48T86_HOUR) & 0x3f; 80 tm->tm_mday = m48t86_readb(dev, M48T86_DOM); 81 /* tm_mon is 0-11 */ 82 tm->tm_mon = m48t86_readb(dev, M48T86_MONTH) - 1; 83 tm->tm_year = m48t86_readb(dev, M48T86_YEAR) + 100; 84 tm->tm_wday = m48t86_readb(dev, M48T86_DOW); 85 } else { 86 /* bcd mode */ 87 tm->tm_sec = bcd2bin(m48t86_readb(dev, M48T86_SEC)); 88 tm->tm_min = bcd2bin(m48t86_readb(dev, M48T86_MIN)); 89 tm->tm_hour = bcd2bin(m48t86_readb(dev, M48T86_HOUR) & 90 0x3f); 91 tm->tm_mday = bcd2bin(m48t86_readb(dev, M48T86_DOM)); 92 /* tm_mon is 0-11 */ 93 tm->tm_mon = bcd2bin(m48t86_readb(dev, M48T86_MONTH)) - 1; 94 tm->tm_year = bcd2bin(m48t86_readb(dev, M48T86_YEAR)) + 100; 95 tm->tm_wday = bcd2bin(m48t86_readb(dev, M48T86_DOW)); 96 } 97 98 /* correct the hour if the clock is in 12h mode */ 99 if (!(reg & M48T86_B_H24)) 100 if (m48t86_readb(dev, M48T86_HOUR) & 0x80) 101 tm->tm_hour += 12; 102 103 return rtc_valid_tm(tm); 104 } 105 106 static int m48t86_rtc_set_time(struct device *dev, struct rtc_time *tm) 107 { 108 unsigned char reg; 109 110 reg = m48t86_readb(dev, M48T86_B); 111 112 /* update flag and 24h mode */ 113 reg |= M48T86_B_SET | M48T86_B_H24; 114 m48t86_writeb(dev, reg, M48T86_B); 115 116 if (reg & M48T86_B_DM) { 117 /* data (binary) mode */ 118 m48t86_writeb(dev, tm->tm_sec, M48T86_SEC); 119 m48t86_writeb(dev, tm->tm_min, M48T86_MIN); 120 m48t86_writeb(dev, tm->tm_hour, M48T86_HOUR); 121 m48t86_writeb(dev, tm->tm_mday, M48T86_DOM); 122 m48t86_writeb(dev, tm->tm_mon + 1, M48T86_MONTH); 123 m48t86_writeb(dev, tm->tm_year % 100, M48T86_YEAR); 124 m48t86_writeb(dev, tm->tm_wday, M48T86_DOW); 125 } else { 126 /* bcd mode */ 127 m48t86_writeb(dev, bin2bcd(tm->tm_sec), M48T86_SEC); 128 m48t86_writeb(dev, bin2bcd(tm->tm_min), M48T86_MIN); 129 m48t86_writeb(dev, bin2bcd(tm->tm_hour), M48T86_HOUR); 130 m48t86_writeb(dev, bin2bcd(tm->tm_mday), M48T86_DOM); 131 m48t86_writeb(dev, bin2bcd(tm->tm_mon + 1), M48T86_MONTH); 132 m48t86_writeb(dev, bin2bcd(tm->tm_year % 100), M48T86_YEAR); 133 m48t86_writeb(dev, bin2bcd(tm->tm_wday), M48T86_DOW); 134 } 135 136 /* update ended */ 137 reg &= ~M48T86_B_SET; 138 m48t86_writeb(dev, reg, M48T86_B); 139 140 return 0; 141 } 142 143 static int m48t86_rtc_proc(struct device *dev, struct seq_file *seq) 144 { 145 unsigned char reg; 146 147 reg = m48t86_readb(dev, M48T86_B); 148 149 seq_printf(seq, "mode\t\t: %s\n", 150 (reg & M48T86_B_DM) ? "binary" : "bcd"); 151 152 reg = m48t86_readb(dev, M48T86_D); 153 154 seq_printf(seq, "battery\t\t: %s\n", 155 (reg & M48T86_D_VRT) ? "ok" : "exhausted"); 156 157 return 0; 158 } 159 160 static const struct rtc_class_ops m48t86_rtc_ops = { 161 .read_time = m48t86_rtc_read_time, 162 .set_time = m48t86_rtc_set_time, 163 .proc = m48t86_rtc_proc, 164 }; 165 166 static ssize_t m48t86_nvram_read(struct file *filp, struct kobject *kobj, 167 struct bin_attribute *attr, 168 char *buf, loff_t off, size_t count) 169 { 170 struct device *dev = kobj_to_dev(kobj); 171 unsigned int i; 172 173 for (i = 0; i < count; i++) 174 buf[i] = m48t86_readb(dev, M48T86_NVRAM(off + i)); 175 176 return count; 177 } 178 179 static ssize_t m48t86_nvram_write(struct file *filp, struct kobject *kobj, 180 struct bin_attribute *attr, 181 char *buf, loff_t off, size_t count) 182 { 183 struct device *dev = kobj_to_dev(kobj); 184 unsigned int i; 185 186 for (i = 0; i < count; i++) 187 m48t86_writeb(dev, buf[i], M48T86_NVRAM(off + i)); 188 189 return count; 190 } 191 192 static BIN_ATTR(nvram, 0644, m48t86_nvram_read, m48t86_nvram_write, 193 M48T86_NVRAM_LEN); 194 195 /* 196 * The RTC is an optional feature at purchase time on some Technologic Systems 197 * boards. Verify that it actually exists by checking if the last two bytes 198 * of the NVRAM can be changed. 199 * 200 * This is based on the method used in their rtc7800.c example. 201 */ 202 static bool m48t86_verify_chip(struct platform_device *pdev) 203 { 204 unsigned int offset0 = M48T86_NVRAM(M48T86_NVRAM_LEN - 2); 205 unsigned int offset1 = M48T86_NVRAM(M48T86_NVRAM_LEN - 1); 206 unsigned char tmp0, tmp1; 207 208 tmp0 = m48t86_readb(&pdev->dev, offset0); 209 tmp1 = m48t86_readb(&pdev->dev, offset1); 210 211 m48t86_writeb(&pdev->dev, 0x00, offset0); 212 m48t86_writeb(&pdev->dev, 0x55, offset1); 213 if (m48t86_readb(&pdev->dev, offset1) == 0x55) { 214 m48t86_writeb(&pdev->dev, 0xaa, offset1); 215 if (m48t86_readb(&pdev->dev, offset1) == 0xaa && 216 m48t86_readb(&pdev->dev, offset0) == 0x00) { 217 m48t86_writeb(&pdev->dev, tmp0, offset0); 218 m48t86_writeb(&pdev->dev, tmp1, offset1); 219 220 return true; 221 } 222 } 223 return false; 224 } 225 226 static int m48t86_rtc_probe(struct platform_device *pdev) 227 { 228 struct m48t86_rtc_info *info; 229 struct resource *res; 230 unsigned char reg; 231 232 info = devm_kzalloc(&pdev->dev, sizeof(*info), GFP_KERNEL); 233 if (!info) 234 return -ENOMEM; 235 236 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 237 if (!res) 238 return -ENODEV; 239 info->index_reg = devm_ioremap_resource(&pdev->dev, res); 240 if (IS_ERR(info->index_reg)) 241 return PTR_ERR(info->index_reg); 242 243 res = platform_get_resource(pdev, IORESOURCE_MEM, 1); 244 if (!res) 245 return -ENODEV; 246 info->data_reg = devm_ioremap_resource(&pdev->dev, res); 247 if (IS_ERR(info->data_reg)) 248 return PTR_ERR(info->data_reg); 249 250 dev_set_drvdata(&pdev->dev, info); 251 252 if (!m48t86_verify_chip(pdev)) { 253 dev_info(&pdev->dev, "RTC not present\n"); 254 return -ENODEV; 255 } 256 257 info->rtc = devm_rtc_device_register(&pdev->dev, "m48t86", 258 &m48t86_rtc_ops, THIS_MODULE); 259 if (IS_ERR(info->rtc)) 260 return PTR_ERR(info->rtc); 261 262 /* read battery status */ 263 reg = m48t86_readb(&pdev->dev, M48T86_D); 264 dev_info(&pdev->dev, "battery %s\n", 265 (reg & M48T86_D_VRT) ? "ok" : "exhausted"); 266 267 if (device_create_bin_file(&pdev->dev, &bin_attr_nvram)) 268 dev_err(&pdev->dev, "failed to create nvram sysfs entry\n"); 269 270 return 0; 271 } 272 273 static int m48t86_rtc_remove(struct platform_device *pdev) 274 { 275 device_remove_bin_file(&pdev->dev, &bin_attr_nvram); 276 return 0; 277 } 278 279 static struct platform_driver m48t86_rtc_platform_driver = { 280 .driver = { 281 .name = "rtc-m48t86", 282 }, 283 .probe = m48t86_rtc_probe, 284 .remove = m48t86_rtc_remove, 285 }; 286 287 module_platform_driver(m48t86_rtc_platform_driver); 288 289 MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>"); 290 MODULE_DESCRIPTION("M48T86 RTC driver"); 291 MODULE_LICENSE("GPL"); 292 MODULE_ALIAS("platform:rtc-m48t86"); 293