From: venkat-prashanth <venkat.prashanth2...@gmail.com> This is a patch to add support for maxim rtc max6916
Signed-off-by:Venkat Prashanth B U <venkat.prashanth2...@gmail.com> --- --- rtc-max6916.c | 157 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ txtfile | 11 ++++ 2 files changed, 168 insertions(+) create mode 100644 rtc-max6916.c create mode 100644 txtfile diff --git a/rtc-max6916.c b/rtc-max6916.c new file mode 100644 index 0000000..7fabaa2 --- /dev/null +++ b/rtc-max6916.c @@ -0,0 +1,157 @@ +/* rtc-max6916.c + * + * Driver for MAXIM max6916 Low Current, SPI Compatible + * Real Time Clock + * + * Author : Venkat Prashanth B U <venkat.prashanth2...@gmail.com> + * + * 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 <linux/init.h> +#include <linux/module.h> +#include <linux/device.h> +#include <linux/platform_device.h> +#include <linux/rtc.h> +#include <linux/spi/spi.h> +#include <linux/bcd.h> + +/* 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 0x00 +#define ADDRESS_REG 0x70 +#define DATA_REG 0x71 +#define ADDRESS_REG_MASK 0xe0 + +static unsigned char get_rtc(unsigned char addr) +{ + outb(addr, ADDRESS_REG); + return inb(DATA_REG); +} + +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 = get_rtc(buf[0]); + dt->tm_min = get_rtc(buf[1]); + dt->tm_hour = get_rtc(buf[2] & 0x00); + dt->tm_mday = get_rtc(buf[3]); + dt->tm_mon = get_rtc(buf[4]) - 1; + dt->tm_wday = get_rtc(buf[5]) - 1; + dt->tm_year = get_rtc(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]; + + buf[0] = MAX6916_CLOCK_BURST & 0x7F; + buf[1] = bcd2bin(dt->tm_sec); + buf[2] = bcd2bin(dt->tm_min); + buf[3] = (bcd2bin(dt->tm_hour) & 0x00); + buf[4] = bcd2bin(dt->tm_mday); + buf[5] = bcd2bin(dt->tm_mon + 1); + buf[6] = bcd2bin(dt->tm_wday + 1); + + /* year in linux is from 1900 i.e in range of 100 + in rtc it is from 00 to 99 */ + dt->tm_year = dt->tm_year % 100; + + buf[7] = bcd2bin(dt->tm_year); + buf[8] = bcd2bin(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 the oscillator , disable the oscillator stop flag, + and glitch filter to reduce current consumption */ + 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, +}; +static void __exit rtc_exit(void) +{ + pr_info("rtc module unloaded\n"); +} + +module_spi_driver(max6916_driver); +MODULE_DESCRIPTION("MAX6916 SPI RTC DRIVER"); +MODULE_AUTHOR("Venkat Prashanth B U <venkat.prashanth2...@gmail.com>"); +MODULE_LICENSE("GPL v2"); diff --git a/txtfile b/txtfile new file mode 100644 index 0000000..1604409 --- /dev/null +++ b/txtfile @@ -0,0 +1,11 @@ +config RTC_DRV_MAX6916 +tristate "Maxim MAX6916" + +help + If you say yes here you get support for the + Maxim MAX6916 chips. + 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. -- 1.9.2