diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig index 18639e0cb6e2..9f8b59d94b1d 100644 --- a/drivers/rtc/Kconfig +++ b/drivers/rtc/Kconfig @@ -670,6 +670,18 @@ config RTC_DRV_DS1390 This driver can also be built as a module. If so, the module will be called rtc-ds1390. +config RTC_DRV_MAX6916 + tristate "Maxim MAX6916" + help + If you say yes here you will get support for the + Maxim MAX6916 SPI RTC chip. + + This driver only supports the RTC feature, and not other chip + features such as alarms. + + This driver can also be built as a module. If so, the module + will be called rtc-max6916. + config RTC_DRV_R9701 tristate "Epson RTC-9701JE" help diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile index ea2833723fa9..024da2723d86 100644 --- a/drivers/rtc/Makefile +++ b/drivers/rtc/Makefile @@ -85,6 +85,7 @@ obj-$(CONFIG_RTC_DRV_M48T59) += rtc-m48t59.o obj-$(CONFIG_RTC_DRV_M48T86) += rtc-m48t86.o obj-$(CONFIG_RTC_DRV_MAX6900) += rtc-max6900.o obj-$(CONFIG_RTC_DRV_MAX6902) += rtc-max6902.o +obj-$(CONFIG_RTC_DRV_MAX6916) += rtc-max6916.o obj-$(CONFIG_RTC_DRV_MAX77686) += rtc-max77686.o obj-$(CONFIG_RTC_DRV_MAX8907) += rtc-max8907.o obj-$(CONFIG_RTC_DRV_MAX8925) += rtc-max8925.o diff --git a/drivers/rtc/rtc-max6916.c b/drivers/rtc/rtc-max6916.c new file mode 100644 index 000000000000..623ab27b2757 --- /dev/null +++ b/drivers/rtc/rtc-max6916.c @@ -0,0 +1,164 @@ +/* rtc-max6916.c + * + * Driver for MAXIM max6916 Low Current, SPI Compatible + * Real Time Clock + * + * Author : Venkat Prashanth B U + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + */ + +#include +#include +#include +#include +#include +#include +#include + +/* Registers in max6916 rtc */ + +#define MAX6916_SECONDS_REG 0x01 +#define MAX6916_MINUTES_REG 0x02 +#define MAX6916_HOURS_REG 0x03 +#define MAX6916_DATE_REG 0x04 +#define MAX6916_MONTH_REG 0x05 +#define MAX6916_DAY_REG 0x06 +#define MAX6916_YEAR_REG 0x07 +#define MAX6916_CONTROL_REG 0x08 +#define MAX6916_STATUS_REG 0x0C +#define MAX6916_CLOCK_BURST 0x3F + +static int max6916_read_reg(struct device *dev, unsigned char address, + unsigned char *data) +{ + struct spi_device *spi = to_spi_device(dev); + + *data = address | 0x80; + + return spi_write_then_read(spi, data, 1, data, 1); +} + +static int max6916_write_reg(struct device *dev, unsigned char address, + unsigned char data) +{ + struct spi_device *spi = to_spi_device(dev); + unsigned char buf[2]; + + buf[0] = address & 0x7F; + buf[1] = data; + + return spi_write_then_read(spi, buf, 2, NULL, 0); +} + +static int max6916_read_time(struct device *dev, struct rtc_time *dt) +{ + struct spi_device *spi = to_spi_device(dev); + int err; + unsigned char buf[8]; + + buf[0] = MAX6916_CLOCK_BURST | 0x80; + + err = spi_write_then_read(spi, buf, 1, buf, 8); + + if (err) + return err; + + dt->tm_sec = bcd2bin(buf[0]); + dt->tm_min = bcd2bin(buf[1]); + dt->tm_hour = bcd2bin(buf[2] & 0x3F); + dt->tm_mday = bcd2bin(buf[3]); + dt->tm_mon = bcd2bin(buf[4]) - 1; + dt->tm_wday = bcd2bin(buf[5]) - 1; + dt->tm_year = bcd2bin(buf[6]) + 100; + + return rtc_valid_tm(dt); +} + +static int max6916_set_time(struct device *dev, struct rtc_time *dt) +{ + struct spi_device *spi = to_spi_device(dev); + unsigned char buf[9]; + + if (dt->tm_year < 100 || dt->tm_year > 199) { + dev_err(&spi->dev, "Year must be between 2000 and 2099. It's %d.\n", + dt->tm_year + 1900); + return -EINVAL; + } + + buf[0] = MAX6916_CLOCK_BURST & 0x7F; + buf[1] = bin2bcd(dt->tm_sec); + buf[2] = bin2bcd(dt->tm_min); + buf[3] = (bin2bcd(dt->tm_hour) & 0X3F); + buf[4] = bin2bcd(dt->tm_mday); + buf[5] = bin2bcd(dt->tm_mon + 1); + buf[6] = bin2bcd(dt->tm_wday + 1); + buf[7] = bin2bcd(dt->tm_year % 100); + buf[8] = bin2bcd(0x00); + + /* write the rtc settings */ + return spi_write_then_read(spi, buf, 9, NULL, 0); +} + +static const struct rtc_class_ops max6916_rtc_ops = { + .read_time = max6916_read_time, + .set_time = max6916_set_time, +}; + +static int max6916_probe(struct spi_device *spi) +{ + struct rtc_device *rtc; + unsigned char data; + int res; + + /* spi setup with max6916 in mode 3 and bits per word as 8 */ + spi->mode = SPI_MODE_3; + spi->bits_per_word = 8; + spi_setup(spi); + + /* RTC Settings */ + res = max6916_read_reg(&spi->dev, MAX6916_SECONDS_REG, &data); + if (res) + return res; + + /* Disable the write protect of rtc */ + max6916_read_reg(&spi->dev, MAX6916_CONTROL_REG, &data); + data = data & ~(1 << 7); + max6916_write_reg(&spi->dev, MAX6916_CONTROL_REG, data); + + /*Enable oscillator,disable oscillator stop flag, glitch filter*/ + max6916_read_reg(&spi->dev, MAX6916_STATUS_REG, &data); + data = data & 0x1B; + max6916_write_reg(&spi->dev, MAX6916_STATUS_REG, data); + + /* display the settings */ + max6916_read_reg(&spi->dev, MAX6916_CONTROL_REG, &data); + dev_info(&spi->dev, "MAX6916 RTC CTRL Reg = 0x%02x\n", data); + + max6916_read_reg(&spi->dev, MAX6916_STATUS_REG, &data); + dev_info(&spi->dev, "MAX6916 RTC Status Reg = 0x%02x\n", data); + + rtc = devm_rtc_device_register(&spi->dev, "max6916", + &max6916_rtc_ops, THIS_MODULE); + if (IS_ERR(rtc)) + return PTR_ERR(rtc); + + spi_set_drvdata(spi, rtc); + + return 0; +} + +static struct spi_driver max6916_driver = { + .driver = { + .name = "max6916", + }, + .probe = max6916_probe, +}; +module_spi_driver(max6916_driver); + +MODULE_DESCRIPTION("MAX6916 SPI RTC DRIVER"); +MODULE_AUTHOR("Venkat Prashanth B U "); +MODULE_LICENSE("GPL v2");