From: venkat-prashanth <[email protected]> This is a patch to add support for maxim rtc MAX6916
Signed-off-by : Venkat Prashanth B U <[email protected]> --- Kconfig | 10 ++++ changeLOG | 36 ++++++++++++ rtc-max6916.c | 172 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 218 insertions(+) diff --git a/drivers/rtcKconfig b/drivers/rtc/Kconfig index e69de29..81aaa1e 100644 --- a/drivers/rtc/Kconfig +++ b/drivers/rtc/Kconfig @@ -0,0 +1,10 @@ +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. diff --git a/changeLOG b/changeLOG index e69de29..6aa0a76 100644 --- a/drivers/rtc/changeLOG +++ b/drivers/rtc/changeLOG @@ -0,0 +1,36 @@ +Changes incorporated after pre-commit review + +1./*created folders +drivers/rtc/rtc-max6916.c +drivers/rtc/Kconfig/ + +2./*deleted the port i/o's since it does not add +any significance in overall system design aspect*/ +/* +#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); +}*/ + +3./* Clock burst value is modified from 0X00 to 0X3F and +further get_rtc() function is replaced with bcd2bin() +since the time in Linux is in binary format so the conversion is done*/ + + +4./*enforced the year range instead of accepting any value +which is as follows: +/* starting from year 2000,limit to 100 years from now +that is subtract the year by 100 */ +dt->tm_year = dt->tm_year % 100; +if(dt->tm_year >= 100) +dt->tm_year -= 100; + +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; +}*/ diff --git a/drivers/rtc/rtc-max6916.c b/drivers/rtc/rtc-max6916.c index e69de29..f5e396f 100644 --- a/drivers/rtc/rtc-max6916.c +++ b/drivers/rtc/rtc-max6916.c @@ -0,0 +1,172 @@ +/* rtc-max6916.c + * + * Driver for MAXIM max6916 Low Current, SPI Compatible + * Real Time Clock + * + * Author : Venkat Prashanth B U <[email protected]> + * + * 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 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]; + + 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); + + /* starting from year 2000,limit to 100 years + from now that is subtract the year by 100 */ + dt->tm_year = dt->tm_year % 100; + if(dt->tm_year >= 100) + dt->tm_year -= 100; + + 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[7] = bin2bcd(dt->tm_year); + 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 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, +}; + +module_spi_driver(max6916_driver); + +MODULE_DESCRIPTION("MAX6916 SPI RTC DRIVER"); +MODULE_AUTHOR("Venkat Prashanth B U <[email protected]>"); +MODULE_LICENSE("GPL v2"); -- 1.9.2
