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 #define DRV_VERSION "0.2" 15 16 struct ds1216_regs { 17 u8 tsec; 18 u8 sec; 19 u8 min; 20 u8 hour; 21 u8 wday; 22 u8 mday; 23 u8 month; 24 u8 year; 25 }; 26 27 #define DS1216_HOUR_1224 (1 << 7) 28 #define DS1216_HOUR_AMPM (1 << 5) 29 30 struct ds1216_priv { 31 struct rtc_device *rtc; 32 void __iomem *ioaddr; 33 }; 34 35 static const u8 magic[] = { 36 0xc5, 0x3a, 0xa3, 0x5c, 0xc5, 0x3a, 0xa3, 0x5c 37 }; 38 39 /* 40 * Read the 64 bit we'd like to have - It a series 41 * of 64 bits showing up in the LSB of the base register. 42 * 43 */ 44 static void ds1216_read(u8 __iomem *ioaddr, u8 *buf) 45 { 46 unsigned char c; 47 int i, j; 48 49 for (i = 0; i < 8; i++) { 50 c = 0; 51 for (j = 0; j < 8; j++) 52 c |= (readb(ioaddr) & 0x1) << j; 53 buf[i] = c; 54 } 55 } 56 57 static void ds1216_write(u8 __iomem *ioaddr, const u8 *buf) 58 { 59 unsigned char c; 60 int i, j; 61 62 for (i = 0; i < 8; i++) { 63 c = buf[i]; 64 for (j = 0; j < 8; j++) { 65 writeb(c, ioaddr); 66 c = c >> 1; 67 } 68 } 69 } 70 71 static void ds1216_switch_ds_to_clock(u8 __iomem *ioaddr) 72 { 73 /* Reset magic pointer */ 74 readb(ioaddr); 75 /* Write 64 bit magic to DS1216 */ 76 ds1216_write(ioaddr, magic); 77 } 78 79 static int ds1216_rtc_read_time(struct device *dev, struct rtc_time *tm) 80 { 81 struct platform_device *pdev = to_platform_device(dev); 82 struct ds1216_priv *priv = platform_get_drvdata(pdev); 83 struct ds1216_regs regs; 84 85 ds1216_switch_ds_to_clock(priv->ioaddr); 86 ds1216_read(priv->ioaddr, (u8 *)®s); 87 88 tm->tm_sec = bcd2bin(regs.sec); 89 tm->tm_min = bcd2bin(regs.min); 90 if (regs.hour & DS1216_HOUR_1224) { 91 /* AM/PM mode */ 92 tm->tm_hour = bcd2bin(regs.hour & 0x1f); 93 if (regs.hour & DS1216_HOUR_AMPM) 94 tm->tm_hour += 12; 95 } else 96 tm->tm_hour = bcd2bin(regs.hour & 0x3f); 97 tm->tm_wday = (regs.wday & 7) - 1; 98 tm->tm_mday = bcd2bin(regs.mday & 0x3f); 99 tm->tm_mon = bcd2bin(regs.month & 0x1f); 100 tm->tm_year = bcd2bin(regs.year); 101 if (tm->tm_year < 70) 102 tm->tm_year += 100; 103 104 return rtc_valid_tm(tm); 105 } 106 107 static int ds1216_rtc_set_time(struct device *dev, struct rtc_time *tm) 108 { 109 struct platform_device *pdev = to_platform_device(dev); 110 struct ds1216_priv *priv = platform_get_drvdata(pdev); 111 struct ds1216_regs regs; 112 113 ds1216_switch_ds_to_clock(priv->ioaddr); 114 ds1216_read(priv->ioaddr, (u8 *)®s); 115 116 regs.tsec = 0; /* clear 0.1 and 0.01 seconds */ 117 regs.sec = bin2bcd(tm->tm_sec); 118 regs.min = bin2bcd(tm->tm_min); 119 regs.hour &= DS1216_HOUR_1224; 120 if (regs.hour && tm->tm_hour > 12) { 121 regs.hour |= DS1216_HOUR_AMPM; 122 tm->tm_hour -= 12; 123 } 124 regs.hour |= bin2bcd(tm->tm_hour); 125 regs.wday &= ~7; 126 regs.wday |= tm->tm_wday; 127 regs.mday = bin2bcd(tm->tm_mday); 128 regs.month = bin2bcd(tm->tm_mon); 129 regs.year = bin2bcd(tm->tm_year % 100); 130 131 ds1216_switch_ds_to_clock(priv->ioaddr); 132 ds1216_write(priv->ioaddr, (u8 *)®s); 133 return 0; 134 } 135 136 static const struct rtc_class_ops ds1216_rtc_ops = { 137 .read_time = ds1216_rtc_read_time, 138 .set_time = ds1216_rtc_set_time, 139 }; 140 141 static int __init ds1216_rtc_probe(struct platform_device *pdev) 142 { 143 struct resource *res; 144 struct ds1216_priv *priv; 145 u8 dummy[8]; 146 147 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 148 if (!res) 149 return -ENODEV; 150 priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL); 151 if (!priv) 152 return -ENOMEM; 153 154 platform_set_drvdata(pdev, priv); 155 156 priv->ioaddr = devm_ioremap_resource(&pdev->dev, res); 157 if (IS_ERR(priv->ioaddr)) 158 return PTR_ERR(priv->ioaddr); 159 160 priv->rtc = devm_rtc_device_register(&pdev->dev, "ds1216", 161 &ds1216_rtc_ops, THIS_MODULE); 162 if (IS_ERR(priv->rtc)) 163 return PTR_ERR(priv->rtc); 164 165 /* dummy read to get clock into a known state */ 166 ds1216_read(priv->ioaddr, dummy); 167 return 0; 168 } 169 170 static struct platform_driver ds1216_rtc_platform_driver = { 171 .driver = { 172 .name = "rtc-ds1216", 173 }, 174 }; 175 176 module_platform_driver_probe(ds1216_rtc_platform_driver, ds1216_rtc_probe); 177 178 MODULE_AUTHOR("Thomas Bogendoerfer <tsbogend@alpha.franken.de>"); 179 MODULE_DESCRIPTION("DS1216 RTC driver"); 180 MODULE_LICENSE("GPL"); 181 MODULE_VERSION(DRV_VERSION); 182 MODULE_ALIAS("platform:rtc-ds1216"); 183