1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * Driver for the SGS-Thomson M48T35 Timekeeper RAM chip 4 * 5 * Copyright (C) 2000 Silicon Graphics, Inc. 6 * Written by Ulf Carlsson (ulfc@engr.sgi.com) 7 * 8 * Copyright (C) 2008 Thomas Bogendoerfer 9 * 10 * Based on code written by Paul Gortmaker. 11 */ 12 13 #include <linux/module.h> 14 #include <linux/rtc.h> 15 #include <linux/slab.h> 16 #include <linux/platform_device.h> 17 #include <linux/bcd.h> 18 #include <linux/io.h> 19 #include <linux/err.h> 20 21 struct m48t35_rtc { 22 u8 pad[0x7ff8]; /* starts at 0x7ff8 */ 23 #ifdef CONFIG_SGI_IP27 24 u8 hour; 25 u8 min; 26 u8 sec; 27 u8 control; 28 u8 year; 29 u8 month; 30 u8 date; 31 u8 day; 32 #else 33 u8 control; 34 u8 sec; 35 u8 min; 36 u8 hour; 37 u8 day; 38 u8 date; 39 u8 month; 40 u8 year; 41 #endif 42 }; 43 44 #define M48T35_RTC_SET 0x80 45 #define M48T35_RTC_READ 0x40 46 47 struct m48t35_priv { 48 struct rtc_device *rtc; 49 struct m48t35_rtc __iomem *reg; 50 size_t size; 51 unsigned long baseaddr; 52 spinlock_t lock; 53 }; 54 55 static int m48t35_read_time(struct device *dev, struct rtc_time *tm) 56 { 57 struct m48t35_priv *priv = dev_get_drvdata(dev); 58 u8 control; 59 60 /* 61 * Only the values that we read from the RTC are set. We leave 62 * tm_wday, tm_yday and tm_isdst untouched. Even though the 63 * RTC has RTC_DAY_OF_WEEK, we ignore it, as it is only updated 64 * by the RTC when initially set to a non-zero value. 65 */ 66 spin_lock_irq(&priv->lock); 67 control = readb(&priv->reg->control); 68 writeb(control | M48T35_RTC_READ, &priv->reg->control); 69 tm->tm_sec = readb(&priv->reg->sec); 70 tm->tm_min = readb(&priv->reg->min); 71 tm->tm_hour = readb(&priv->reg->hour); 72 tm->tm_mday = readb(&priv->reg->date); 73 tm->tm_mon = readb(&priv->reg->month); 74 tm->tm_year = readb(&priv->reg->year); 75 writeb(control, &priv->reg->control); 76 spin_unlock_irq(&priv->lock); 77 78 tm->tm_sec = bcd2bin(tm->tm_sec); 79 tm->tm_min = bcd2bin(tm->tm_min); 80 tm->tm_hour = bcd2bin(tm->tm_hour); 81 tm->tm_mday = bcd2bin(tm->tm_mday); 82 tm->tm_mon = bcd2bin(tm->tm_mon); 83 tm->tm_year = bcd2bin(tm->tm_year); 84 85 /* 86 * Account for differences between how the RTC uses the values 87 * and how they are defined in a struct rtc_time; 88 */ 89 tm->tm_year += 70; 90 if (tm->tm_year <= 69) 91 tm->tm_year += 100; 92 93 tm->tm_mon--; 94 return 0; 95 } 96 97 static int m48t35_set_time(struct device *dev, struct rtc_time *tm) 98 { 99 struct m48t35_priv *priv = dev_get_drvdata(dev); 100 unsigned char mon, day, hrs, min, sec; 101 unsigned int yrs; 102 u8 control; 103 104 yrs = tm->tm_year + 1900; 105 mon = tm->tm_mon + 1; /* tm_mon starts at zero */ 106 day = tm->tm_mday; 107 hrs = tm->tm_hour; 108 min = tm->tm_min; 109 sec = tm->tm_sec; 110 111 if (yrs < 1970) 112 return -EINVAL; 113 114 yrs -= 1970; 115 if (yrs > 255) /* They are unsigned */ 116 return -EINVAL; 117 118 if (yrs > 169) 119 return -EINVAL; 120 121 if (yrs >= 100) 122 yrs -= 100; 123 124 sec = bin2bcd(sec); 125 min = bin2bcd(min); 126 hrs = bin2bcd(hrs); 127 day = bin2bcd(day); 128 mon = bin2bcd(mon); 129 yrs = bin2bcd(yrs); 130 131 spin_lock_irq(&priv->lock); 132 control = readb(&priv->reg->control); 133 writeb(control | M48T35_RTC_SET, &priv->reg->control); 134 writeb(yrs, &priv->reg->year); 135 writeb(mon, &priv->reg->month); 136 writeb(day, &priv->reg->date); 137 writeb(hrs, &priv->reg->hour); 138 writeb(min, &priv->reg->min); 139 writeb(sec, &priv->reg->sec); 140 writeb(control, &priv->reg->control); 141 spin_unlock_irq(&priv->lock); 142 return 0; 143 } 144 145 static const struct rtc_class_ops m48t35_ops = { 146 .read_time = m48t35_read_time, 147 .set_time = m48t35_set_time, 148 }; 149 150 static int m48t35_probe(struct platform_device *pdev) 151 { 152 struct resource *res; 153 struct m48t35_priv *priv; 154 155 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 156 if (!res) 157 return -ENODEV; 158 priv = devm_kzalloc(&pdev->dev, sizeof(struct m48t35_priv), GFP_KERNEL); 159 if (!priv) 160 return -ENOMEM; 161 162 priv->size = resource_size(res); 163 if (!devm_request_mem_region(&pdev->dev, res->start, priv->size, 164 pdev->name)) 165 return -EBUSY; 166 167 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 }, 185 .probe = m48t35_probe, 186 }; 187 188 module_platform_driver(m48t35_platform_driver); 189 190 MODULE_AUTHOR("Thomas Bogendoerfer <tsbogend@alpha.franken.de>"); 191 MODULE_DESCRIPTION("M48T35 RTC driver"); 192 MODULE_LICENSE("GPL"); 193 MODULE_ALIAS("platform:rtc-m48t35"); 194