diff options
Diffstat (limited to 'drivers/rtc/rtc-ds1216.c')
| -rw-r--r-- | drivers/rtc/rtc-ds1216.c | 174 |
1 files changed, 174 insertions, 0 deletions
diff --git a/drivers/rtc/rtc-ds1216.c b/drivers/rtc/rtc-ds1216.c new file mode 100644 index 000000000..7eeb3f359 --- /dev/null +++ b/drivers/rtc/rtc-ds1216.c @@ -0,0 +1,174 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Dallas DS1216 RTC driver + * + * Copyright (c) 2007 Thomas Bogendoerfer + * + */ + +#include <linux/module.h> +#include <linux/rtc.h> +#include <linux/platform_device.h> +#include <linux/bcd.h> +#include <linux/slab.h> + +struct ds1216_regs { + u8 tsec; + u8 sec; + u8 min; + u8 hour; + u8 wday; + u8 mday; + u8 month; + u8 year; +}; + +#define DS1216_HOUR_1224 (1 << 7) +#define DS1216_HOUR_AMPM (1 << 5) + +struct ds1216_priv { + struct rtc_device *rtc; + void __iomem *ioaddr; +}; + +static const u8 magic[] = { + 0xc5, 0x3a, 0xa3, 0x5c, 0xc5, 0x3a, 0xa3, 0x5c +}; + +/* + * Read the 64 bit we'd like to have - It a series + * of 64 bits showing up in the LSB of the base register. + * + */ +static void ds1216_read(u8 __iomem *ioaddr, u8 *buf) +{ + unsigned char c; + int i, j; + + for (i = 0; i < 8; i++) { + c = 0; + for (j = 0; j < 8; j++) + c |= (readb(ioaddr) & 0x1) << j; + buf[i] = c; + } +} + +static void ds1216_write(u8 __iomem *ioaddr, const u8 *buf) +{ + unsigned char c; + int i, j; + + for (i = 0; i < 8; i++) { + c = buf[i]; + for (j = 0; j < 8; j++) { + writeb(c, ioaddr); + c = c >> 1; + } + } +} + +static void ds1216_switch_ds_to_clock(u8 __iomem *ioaddr) +{ + /* Reset magic pointer */ + readb(ioaddr); + /* Write 64 bit magic to DS1216 */ + ds1216_write(ioaddr, magic); +} + +static int ds1216_rtc_read_time(struct device *dev, struct rtc_time *tm) +{ + struct ds1216_priv *priv = dev_get_drvdata(dev); + struct ds1216_regs regs; + + ds1216_switch_ds_to_clock(priv->ioaddr); + ds1216_read(priv->ioaddr, (u8 *)®s); + + tm->tm_sec = bcd2bin(regs.sec); + tm->tm_min = bcd2bin(regs.min); + if (regs.hour & DS1216_HOUR_1224) { + /* AM/PM mode */ + tm->tm_hour = bcd2bin(regs.hour & 0x1f); + if (regs.hour & DS1216_HOUR_AMPM) + tm->tm_hour += 12; + } else + tm->tm_hour = bcd2bin(regs.hour & 0x3f); + tm->tm_wday = (regs.wday & 7) - 1; + tm->tm_mday = bcd2bin(regs.mday & 0x3f); + tm->tm_mon = bcd2bin(regs.month & 0x1f); + tm->tm_year = bcd2bin(regs.year); + if (tm->tm_year < 70) + tm->tm_year += 100; + + return 0; +} + +static int ds1216_rtc_set_time(struct device *dev, struct rtc_time *tm) +{ + struct ds1216_priv *priv = dev_get_drvdata(dev); + struct ds1216_regs regs; + + ds1216_switch_ds_to_clock(priv->ioaddr); + ds1216_read(priv->ioaddr, (u8 *)®s); + + regs.tsec = 0; /* clear 0.1 and 0.01 seconds */ + regs.sec = bin2bcd(tm->tm_sec); + regs.min = bin2bcd(tm->tm_min); + regs.hour &= DS1216_HOUR_1224; + if (regs.hour && tm->tm_hour > 12) { + regs.hour |= DS1216_HOUR_AMPM; + tm->tm_hour -= 12; + } + regs.hour |= bin2bcd(tm->tm_hour); + regs.wday &= ~7; + regs.wday |= tm->tm_wday; + regs.mday = bin2bcd(tm->tm_mday); + regs.month = bin2bcd(tm->tm_mon); + regs.year = bin2bcd(tm->tm_year % 100); + + ds1216_switch_ds_to_clock(priv->ioaddr); + ds1216_write(priv->ioaddr, (u8 *)®s); + return 0; +} + +static const struct rtc_class_ops ds1216_rtc_ops = { + .read_time = ds1216_rtc_read_time, + .set_time = ds1216_rtc_set_time, +}; + +static int __init ds1216_rtc_probe(struct platform_device *pdev) +{ + struct ds1216_priv *priv; + u8 dummy[8]; + + priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL); + if (!priv) + return -ENOMEM; + + platform_set_drvdata(pdev, priv); + + priv->ioaddr = devm_platform_ioremap_resource(pdev, 0); + if (IS_ERR(priv->ioaddr)) + return PTR_ERR(priv->ioaddr); + + priv->rtc = devm_rtc_device_register(&pdev->dev, "ds1216", + &ds1216_rtc_ops, THIS_MODULE); + if (IS_ERR(priv->rtc)) + return PTR_ERR(priv->rtc); + + /* dummy read to get clock into a known state */ + ds1216_read(priv->ioaddr, dummy); + return 0; +} + +static struct platform_driver ds1216_rtc_platform_driver = { + .driver = { + .name = "rtc-ds1216", + }, +}; + +module_platform_driver_probe(ds1216_rtc_platform_driver, ds1216_rtc_probe); + +MODULE_AUTHOR("Thomas Bogendoerfer <tsbogend@alpha.franken.de>"); +MODULE_DESCRIPTION("DS1216 RTC driver"); +MODULE_LICENSE("GPL"); +MODULE_ALIAS("platform:rtc-ds1216"); |