1 /* 2 * Driver for the SGS-Thomson M48T35 Timekeeper RAM chip 3 * 4 * Copyright (C) 2000 Silicon Graphics, Inc. 5 * Written by Ulf Carlsson (ulfc@engr.sgi.com) 6 * 7 * Copyright (C) 2008 Thomas Bogendoerfer 8 * 9 * Based on code written by Paul Gortmaker. 10 * 11 * This program is free software; you can redistribute it and/or modify it 12 * under the terms of the GNU General Public License as published by the 13 * Free Software Foundation; either version 2 of the License, or (at your 14 * option) any later version. 15 */ 16 17 #include <linux/module.h> 18 #include <linux/rtc.h> 19 #include <linux/slab.h> 20 #include <linux/platform_device.h> 21 #include <linux/bcd.h> 22 #include <linux/io.h> 23 24 #define DRV_VERSION "1.0" 25 26 struct m48t35_rtc { 27 u8 pad[0x7ff8]; /* starts at 0x7ff8 */ 28 u8 control; 29 u8 sec; 30 u8 min; 31 u8 hour; 32 u8 day; 33 u8 date; 34 u8 month; 35 u8 year; 36 }; 37 38 #define M48T35_RTC_SET 0x80 39 #define M48T35_RTC_READ 0x40 40 41 struct m48t35_priv { 42 struct rtc_device *rtc; 43 struct m48t35_rtc __iomem *reg; 44 size_t size; 45 unsigned long baseaddr; 46 spinlock_t lock; 47 }; 48 49 static int m48t35_read_time(struct device *dev, struct rtc_time *tm) 50 { 51 struct m48t35_priv *priv = dev_get_drvdata(dev); 52 u8 control; 53 54 /* 55 * Only the values that we read from the RTC are set. We leave 56 * tm_wday, tm_yday and tm_isdst untouched. Even though the 57 * RTC has RTC_DAY_OF_WEEK, we ignore it, as it is only updated 58 * by the RTC when initially set to a non-zero value. 59 */ 60 spin_lock_irq(&priv->lock); 61 control = readb(&priv->reg->control); 62 writeb(control | M48T35_RTC_READ, &priv->reg->control); 63 tm->tm_sec = readb(&priv->reg->sec); 64 tm->tm_min = readb(&priv->reg->min); 65 tm->tm_hour = readb(&priv->reg->hour); 66 tm->tm_mday = readb(&priv->reg->date); 67 tm->tm_mon = readb(&priv->reg->month); 68 tm->tm_year = readb(&priv->reg->year); 69 writeb(control, &priv->reg->control); 70 spin_unlock_irq(&priv->lock); 71 72 tm->tm_sec = bcd2bin(tm->tm_sec); 73 tm->tm_min = bcd2bin(tm->tm_min); 74 tm->tm_hour = bcd2bin(tm->tm_hour); 75 tm->tm_mday = bcd2bin(tm->tm_mday); 76 tm->tm_mon = bcd2bin(tm->tm_mon); 77 tm->tm_year = bcd2bin(tm->tm_year); 78 79 /* 80 * Account for differences between how the RTC uses the values 81 * and how they are defined in a struct rtc_time; 82 */ 83 tm->tm_year += 70; 84 if (tm->tm_year <= 69) 85 tm->tm_year += 100; 86 87 tm->tm_mon--; 88 return rtc_valid_tm(tm); 89 } 90 91 static int m48t35_set_time(struct device *dev, struct rtc_time *tm) 92 { 93 struct m48t35_priv *priv = dev_get_drvdata(dev); 94 unsigned char mon, day, hrs, min, sec; 95 unsigned int yrs; 96 u8 control; 97 98 yrs = tm->tm_year + 1900; 99 mon = tm->tm_mon + 1; /* tm_mon starts at zero */ 100 day = tm->tm_mday; 101 hrs = tm->tm_hour; 102 min = tm->tm_min; 103 sec = tm->tm_sec; 104 105 if (yrs < 1970) 106 return -EINVAL; 107 108 yrs -= 1970; 109 if (yrs > 255) /* They are unsigned */ 110 return -EINVAL; 111 112 if (yrs > 169) 113 return -EINVAL; 114 115 if (yrs >= 100) 116 yrs -= 100; 117 118 sec = bin2bcd(sec); 119 min = bin2bcd(min); 120 hrs = bin2bcd(hrs); 121 day = bin2bcd(day); 122 mon = bin2bcd(mon); 123 yrs = bin2bcd(yrs); 124 125 spin_lock_irq(&priv->lock); 126 control = readb(&priv->reg->control); 127 writeb(control | M48T35_RTC_SET, &priv->reg->control); 128 writeb(yrs, &priv->reg->year); 129 writeb(mon, &priv->reg->month); 130 writeb(day, &priv->reg->date); 131 writeb(hrs, &priv->reg->hour); 132 writeb(min, &priv->reg->min); 133 writeb(sec, &priv->reg->sec); 134 writeb(control, &priv->reg->control); 135 spin_unlock_irq(&priv->lock); 136 return 0; 137 } 138 139 static const struct rtc_class_ops m48t35_ops = { 140 .read_time = m48t35_read_time, 141 .set_time = m48t35_set_time, 142 }; 143 144 static int m48t35_probe(struct platform_device *pdev) 145 { 146 struct resource *res; 147 struct m48t35_priv *priv; 148 149 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 150 if (!res) 151 return -ENODEV; 152 priv = devm_kzalloc(&pdev->dev, sizeof(struct m48t35_priv), GFP_KERNEL); 153 if (!priv) 154 return -ENOMEM; 155 156 priv->size = resource_size(res); 157 /* 158 * kludge: remove the #ifndef after ioc3 resource 159 * conflicts are resolved 160 */ 161 #ifndef CONFIG_SGI_IP27 162 if (!devm_request_mem_region(&pdev->dev, res->start, priv->size, 163 pdev->name)) 164 return -EBUSY; 165 #endif 166 priv->baseaddr = res->start; 167 priv->reg = devm_ioremap(&pdev->dev, priv->baseaddr, priv->size); 168 if (!priv->reg) 169 return -ENOMEM; 170 171 spin_lock_init(&priv->lock); 172 173 platform_set_drvdata(pdev, priv); 174 175 priv->rtc = devm_rtc_device_register(&pdev->dev, "m48t35", 176 &m48t35_ops, THIS_MODULE); 177 if (IS_ERR(priv->rtc)) 178 return PTR_ERR(priv->rtc); 179 180 return 0; 181 } 182 183 static int m48t35_remove(struct platform_device *pdev) 184 { 185 return 0; 186 } 187 188 static struct platform_driver m48t35_platform_driver = { 189 .driver = { 190 .name = "rtc-m48t35", 191 .owner = THIS_MODULE, 192 }, 193 .probe = m48t35_probe, 194 .remove = m48t35_remove, 195 }; 196 197 module_platform_driver(m48t35_platform_driver); 198 199 MODULE_AUTHOR("Thomas Bogendoerfer <tsbogend@alpha.franken.de>"); 200 MODULE_DESCRIPTION("M48T35 RTC driver"); 201 MODULE_LICENSE("GPL"); 202 MODULE_VERSION(DRV_VERSION); 203 MODULE_ALIAS("platform:rtc-m48t35"); 204