1 /* 2 * Dallas DS1216 RTC driver 3 * 4 * Copyright (c) 2007 Thomas Bogendoerfer 5 * 6 */ 7 8 #include <linux/module.h> 9 #include <linux/rtc.h> 10 #include <linux/platform_device.h> 11 #include <linux/bcd.h> 12 #include <linux/slab.h> 13 14 struct ds1216_regs { 15 u8 tsec; 16 u8 sec; 17 u8 min; 18 u8 hour; 19 u8 wday; 20 u8 mday; 21 u8 month; 22 u8 year; 23 }; 24 25 #define DS1216_HOUR_1224 (1 << 7) 26 #define DS1216_HOUR_AMPM (1 << 5) 27 28 struct ds1216_priv { 29 struct rtc_device *rtc; 30 void __iomem *ioaddr; 31 }; 32 33 static const u8 magic[] = { 34 0xc5, 0x3a, 0xa3, 0x5c, 0xc5, 0x3a, 0xa3, 0x5c 35 }; 36 37 /* 38 * Read the 64 bit we'd like to have - It a series 39 * of 64 bits showing up in the LSB of the base register. 40 * 41 */ 42 static void ds1216_read(u8 __iomem *ioaddr, u8 *buf) 43 { 44 unsigned char c; 45 int i, j; 46 47 for (i = 0; i < 8; i++) { 48 c = 0; 49 for (j = 0; j < 8; j++) 50 c |= (readb(ioaddr) & 0x1) << j; 51 buf[i] = c; 52 } 53 } 54 55 static void ds1216_write(u8 __iomem *ioaddr, const u8 *buf) 56 { 57 unsigned char c; 58 int i, j; 59 60 for (i = 0; i < 8; i++) { 61 c = buf[i]; 62 for (j = 0; j < 8; j++) { 63 writeb(c, ioaddr); 64 c = c >> 1; 65 } 66 } 67 } 68 69 static void ds1216_switch_ds_to_clock(u8 __iomem *ioaddr) 70 { 71 /* Reset magic pointer */ 72 readb(ioaddr); 73 /* Write 64 bit magic to DS1216 */ 74 ds1216_write(ioaddr, magic); 75 } 76 77 static int ds1216_rtc_read_time(struct device *dev, struct rtc_time *tm) 78 { 79 struct ds1216_priv *priv = dev_get_drvdata(dev); 80 struct ds1216_regs regs; 81 82 ds1216_switch_ds_to_clock(priv->ioaddr); 83 ds1216_read(priv->ioaddr, (u8 *)®s); 84 85 tm->tm_sec = bcd2bin(regs.sec); 86 tm->tm_min = bcd2bin(regs.min); 87 if (regs.hour & DS1216_HOUR_1224) { 88 /* AM/PM mode */ 89 tm->tm_hour = bcd2bin(regs.hour & 0x1f); 90 if (regs.hour & DS1216_HOUR_AMPM) 91 tm->tm_hour += 12; 92 } else 93 tm->tm_hour = bcd2bin(regs.hour & 0x3f); 94 tm->tm_wday = (regs.wday & 7) - 1; 95 tm->tm_mday = bcd2bin(regs.mday & 0x3f); 96 tm->tm_mon = bcd2bin(regs.month & 0x1f); 97 tm->tm_year = bcd2bin(regs.year); 98 if (tm->tm_year < 70) 99 tm->tm_year += 100; 100 101 return 0; 102 } 103 104 static int ds1216_rtc_set_time(struct device *dev, struct rtc_time *tm) 105 { 106 struct ds1216_priv *priv = dev_get_drvdata(dev); 107 struct ds1216_regs regs; 108 109 ds1216_switch_ds_to_clock(priv->ioaddr); 110 ds1216_read(priv->ioaddr, (u8 *)®s); 111 112 regs.tsec = 0; /* clear 0.1 and 0.01 seconds */ 113 regs.sec = bin2bcd(tm->tm_sec); 114 regs.min = bin2bcd(tm->tm_min); 115 regs.hour &= DS1216_HOUR_1224; 116 if (regs.hour && tm->tm_hour > 12) { 117 regs.hour |= DS1216_HOUR_AMPM; 118 tm->tm_hour -= 12; 119 } 120 regs.hour |= bin2bcd(tm->tm_hour); 121 regs.wday &= ~7; 122 regs.wday |= tm->tm_wday; 123 regs.mday = bin2bcd(tm->tm_mday); 124 regs.month = bin2bcd(tm->tm_mon); 125 regs.year = bin2bcd(tm->tm_year % 100); 126 127 ds1216_switch_ds_to_clock(priv->ioaddr); 128 ds1216_write(priv->ioaddr, (u8 *)®s); 129 return 0; 130 } 131 132 static const struct rtc_class_ops ds1216_rtc_ops = { 133 .read_time = ds1216_rtc_read_time, 134 .set_time = ds1216_rtc_set_time, 135 }; 136 137 static int __init ds1216_rtc_probe(struct platform_device *pdev) 138 { 139 struct resource *res; 140 struct ds1216_priv *priv; 141 u8 dummy[8]; 142 143 priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL); 144 if (!priv) 145 return -ENOMEM; 146 147 platform_set_drvdata(pdev, priv); 148 149 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 150 priv->ioaddr = devm_ioremap_resource(&pdev->dev, res); 151 if (IS_ERR(priv->ioaddr)) 152 return PTR_ERR(priv->ioaddr); 153 154 priv->rtc = devm_rtc_device_register(&pdev->dev, "ds1216", 155 &ds1216_rtc_ops, THIS_MODULE); 156 if (IS_ERR(priv->rtc)) 157 return PTR_ERR(priv->rtc); 158 159 /* dummy read to get clock into a known state */ 160 ds1216_read(priv->ioaddr, dummy); 161 return 0; 162 } 163 164 static struct platform_driver ds1216_rtc_platform_driver = { 165 .driver = { 166 .name = "rtc-ds1216", 167 }, 168 }; 169 170 module_platform_driver_probe(ds1216_rtc_platform_driver, ds1216_rtc_probe); 171 172 MODULE_AUTHOR("Thomas Bogendoerfer <tsbogend@alpha.franken.de>"); 173 MODULE_DESCRIPTION("DS1216 RTC driver"); 174 MODULE_LICENSE("GPL"); 175 MODULE_ALIAS("platform:rtc-ds1216"); 176