1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Dallas DS1216 RTC driver 4 * 5 * Copyright (c) 2007 Thomas Bogendoerfer 6 * 7 */ 8 9 #include <linux/module.h> 10 #include <linux/rtc.h> 11 #include <linux/platform_device.h> 12 #include <linux/bcd.h> 13 #include <linux/slab.h> 14 15 struct ds1216_regs { 16 u8 tsec; 17 u8 sec; 18 u8 min; 19 u8 hour; 20 u8 wday; 21 u8 mday; 22 u8 month; 23 u8 year; 24 }; 25 26 #define DS1216_HOUR_1224 (1 << 7) 27 #define DS1216_HOUR_AMPM (1 << 5) 28 29 struct ds1216_priv { 30 struct rtc_device *rtc; 31 void __iomem *ioaddr; 32 }; 33 34 static const u8 magic[] = { 35 0xc5, 0x3a, 0xa3, 0x5c, 0xc5, 0x3a, 0xa3, 0x5c 36 }; 37 38 /* 39 * Read the 64 bit we'd like to have - It a series 40 * of 64 bits showing up in the LSB of the base register. 41 * 42 */ 43 static void ds1216_read(u8 __iomem *ioaddr, u8 *buf) 44 { 45 unsigned char c; 46 int i, j; 47 48 for (i = 0; i < 8; i++) { 49 c = 0; 50 for (j = 0; j < 8; j++) 51 c |= (readb(ioaddr) & 0x1) << j; 52 buf[i] = c; 53 } 54 } 55 56 static void ds1216_write(u8 __iomem *ioaddr, const u8 *buf) 57 { 58 unsigned char c; 59 int i, j; 60 61 for (i = 0; i < 8; i++) { 62 c = buf[i]; 63 for (j = 0; j < 8; j++) { 64 writeb(c, ioaddr); 65 c = c >> 1; 66 } 67 } 68 } 69 70 static void ds1216_switch_ds_to_clock(u8 __iomem *ioaddr) 71 { 72 /* Reset magic pointer */ 73 readb(ioaddr); 74 /* Write 64 bit magic to DS1216 */ 75 ds1216_write(ioaddr, magic); 76 } 77 78 static int ds1216_rtc_read_time(struct device *dev, struct rtc_time *tm) 79 { 80 struct ds1216_priv *priv = dev_get_drvdata(dev); 81 struct ds1216_regs regs; 82 83 ds1216_switch_ds_to_clock(priv->ioaddr); 84 ds1216_read(priv->ioaddr, (u8 *)®s); 85 86 tm->tm_sec = bcd2bin(regs.sec); 87 tm->tm_min = bcd2bin(regs.min); 88 if (regs.hour & DS1216_HOUR_1224) { 89 /* AM/PM mode */ 90 tm->tm_hour = bcd2bin(regs.hour & 0x1f); 91 if (regs.hour & DS1216_HOUR_AMPM) 92 tm->tm_hour += 12; 93 } else 94 tm->tm_hour = bcd2bin(regs.hour & 0x3f); 95 tm->tm_wday = (regs.wday & 7) - 1; 96 tm->tm_mday = bcd2bin(regs.mday & 0x3f); 97 tm->tm_mon = bcd2bin(regs.month & 0x1f); 98 tm->tm_year = bcd2bin(regs.year); 99 if (tm->tm_year < 70) 100 tm->tm_year += 100; 101 102 return 0; 103 } 104 105 static int ds1216_rtc_set_time(struct device *dev, struct rtc_time *tm) 106 { 107 struct ds1216_priv *priv = dev_get_drvdata(dev); 108 struct ds1216_regs regs; 109 110 ds1216_switch_ds_to_clock(priv->ioaddr); 111 ds1216_read(priv->ioaddr, (u8 *)®s); 112 113 regs.tsec = 0; /* clear 0.1 and 0.01 seconds */ 114 regs.sec = bin2bcd(tm->tm_sec); 115 regs.min = bin2bcd(tm->tm_min); 116 regs.hour &= DS1216_HOUR_1224; 117 if (regs.hour && tm->tm_hour > 12) { 118 regs.hour |= DS1216_HOUR_AMPM; 119 tm->tm_hour -= 12; 120 } 121 regs.hour |= bin2bcd(tm->tm_hour); 122 regs.wday &= ~7; 123 regs.wday |= tm->tm_wday; 124 regs.mday = bin2bcd(tm->tm_mday); 125 regs.month = bin2bcd(tm->tm_mon); 126 regs.year = bin2bcd(tm->tm_year % 100); 127 128 ds1216_switch_ds_to_clock(priv->ioaddr); 129 ds1216_write(priv->ioaddr, (u8 *)®s); 130 return 0; 131 } 132 133 static const struct rtc_class_ops ds1216_rtc_ops = { 134 .read_time = ds1216_rtc_read_time, 135 .set_time = ds1216_rtc_set_time, 136 }; 137 138 static int __init ds1216_rtc_probe(struct platform_device *pdev) 139 { 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 priv->ioaddr = devm_platform_ioremap_resource(pdev, 0); 150 if (IS_ERR(priv->ioaddr)) 151 return PTR_ERR(priv->ioaddr); 152 153 priv->rtc = devm_rtc_device_register(&pdev->dev, "ds1216", 154 &ds1216_rtc_ops, THIS_MODULE); 155 if (IS_ERR(priv->rtc)) 156 return PTR_ERR(priv->rtc); 157 158 /* dummy read to get clock into a known state */ 159 ds1216_read(priv->ioaddr, dummy); 160 return 0; 161 } 162 163 static struct platform_driver ds1216_rtc_platform_driver = { 164 .driver = { 165 .name = "rtc-ds1216", 166 }, 167 }; 168 169 module_platform_driver_probe(ds1216_rtc_platform_driver, ds1216_rtc_probe); 170 171 MODULE_AUTHOR("Thomas Bogendoerfer <tsbogend@alpha.franken.de>"); 172 MODULE_DESCRIPTION("DS1216 RTC driver"); 173 MODULE_LICENSE("GPL"); 174 MODULE_ALIAS("platform:rtc-ds1216"); 175