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