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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * Dallas DS1216 RTC driver4 *5 * Copyright (c) 2007 Thomas Bogendoerfer6 *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 15struct 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 29struct ds1216_priv {30 struct rtc_device *rtc;31 void __iomem *ioaddr;32};33 34static const u8 magic[] = {35 0xc5, 0x3a, 0xa3, 0x5c, 0xc5, 0x3a, 0xa3, 0x5c36};37 38/*39 * Read the 64 bit we'd like to have - It a series40 * of 64 bits showing up in the LSB of the base register.41 *42 */43static 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 56static 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 70static 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 78static 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 } else94 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 105static 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 133static const struct rtc_class_ops ds1216_rtc_ops = {134 .read_time = ds1216_rtc_read_time,135 .set_time = ds1216_rtc_set_time,136};137 138static 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 163static struct platform_driver ds1216_rtc_platform_driver = {164 .driver = {165 .name = "rtc-ds1216",166 },167};168 169module_platform_driver_probe(ds1216_rtc_platform_driver, ds1216_rtc_probe);170 171MODULE_AUTHOR("Thomas Bogendoerfer <tsbogend@alpha.franken.de>");172MODULE_DESCRIPTION("DS1216 RTC driver");173MODULE_LICENSE("GPL");174MODULE_ALIAS("platform:rtc-ds1216");175