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