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