diff options
Diffstat (limited to 'drivers/rtc/rtc-max6902.c')
| -rw-r--r-- | drivers/rtc/rtc-max6902.c | 286 |
1 files changed, 286 insertions, 0 deletions
diff --git a/drivers/rtc/rtc-max6902.c b/drivers/rtc/rtc-max6902.c new file mode 100644 index 00000000000..2c9739562b5 --- /dev/null +++ b/drivers/rtc/rtc-max6902.c @@ -0,0 +1,286 @@ +/* drivers/char/max6902.c + * + * Copyright (C) 2006 8D Technologies inc. + * Copyright (C) 2004 Compulab Ltd. + * + * 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. + * + * Driver for MAX6902 spi RTC + * + * Changelog: + * + * 24-May-2006: Raphael Assenat <raph@8d.com> + * - Major rework + * Converted to rtc_device and uses the SPI layer. + * + * ??-???-2005: Someone at Compulab + * - Initial driver creation. + */ + +#include <linux/config.h> +#include <linux/module.h> +#include <linux/version.h> + +#include <linux/kernel.h> +#include <linux/platform_device.h> +#include <linux/init.h> +#include <linux/rtc.h> +#include <linux/spi/spi.h> +#include <linux/bcd.h> +#include <linux/delay.h> + +#define MAX6902_REG_SECONDS 0x01 +#define MAX6902_REG_MINUTES 0x03 +#define MAX6902_REG_HOURS 0x05 +#define MAX6902_REG_DATE 0x07 +#define MAX6902_REG_MONTH 0x09 +#define MAX6902_REG_DAY 0x0B +#define MAX6902_REG_YEAR 0x0D +#define MAX6902_REG_CONTROL 0x0F +#define MAX6902_REG_CENTURY 0x13 + +#undef MAX6902_DEBUG + +struct max6902 { + struct rtc_device *rtc; + u8 buf[9]; /* Burst read cmd + 8 registers */ + u8 tx_buf[2]; + u8 rx_buf[2]; +}; + +static void max6902_set_reg(struct device *dev, unsigned char address, + unsigned char data) +{ + struct spi_device *spi = to_spi_device(dev); + unsigned char buf[2]; + + /* MSB must be '0' to write */ + buf[0] = address & 0x7f; + buf[1] = data; + + spi_write(spi, buf, 2); +} + +static int max6902_get_reg(struct device *dev, unsigned char address, + unsigned char *data) +{ + struct spi_device *spi = to_spi_device(dev); + struct max6902 *chip = dev_get_drvdata(dev); + struct spi_message message; + struct spi_transfer xfer; + int status; + + if (!data) + return -EINVAL; + + /* Build our spi message */ + spi_message_init(&message); + memset(&xfer, 0, sizeof(xfer)); + xfer.len = 2; + /* Can tx_buf and rx_buf be equal? The doc in spi.h is not sure... */ + xfer.tx_buf = chip->tx_buf; + xfer.rx_buf = chip->rx_buf; + + /* Set MSB to indicate read */ + chip->tx_buf[0] = address | 0x80; + + spi_message_add_tail(&xfer, &message); + + /* do the i/o */ + status = spi_sync(spi, &message); + if (status == 0) + status = message.status; + else + return status; + + *data = chip->rx_buf[1]; + + return status; +} + +static int max6902_get_datetime(struct device *dev, struct rtc_time *dt) +{ + unsigned char tmp; + int century; + int err; + struct spi_device *spi = to_spi_device(dev); + struct max6902 *chip = dev_get_drvdata(dev); + struct spi_message message; + struct spi_transfer xfer; + int status; + + err = max6902_get_reg(dev, MAX6902_REG_CENTURY, &tmp); + if (err) + return err; + + /* build the message */ + spi_message_init(&message); + memset(&xfer, 0, sizeof(xfer)); + xfer.len = 1 + 7; /* Burst read command + 7 registers */ + xfer.tx_buf = chip->buf; + xfer.rx_buf = chip->buf; + chip->buf[0] = 0xbf; /* Burst read */ + spi_message_add_tail(&xfer, &message); + + /* do the i/o */ + status = spi_sync(spi, &message); + if (status == 0) + status = message.status; + else + return status; + + /* The chip sends data in this order: + * Seconds, Minutes, Hours, Date, Month, Day, Year */ + dt->tm_sec = BCD2BIN(chip->buf[1]); + dt->tm_min = BCD2BIN(chip->buf[2]); + dt->tm_hour = BCD2BIN(chip->buf[3]); + dt->tm_mday = BCD2BIN(chip->buf[4]); + dt->tm_mon = BCD2BIN(chip->buf[5] - 1); + dt->tm_wday = BCD2BIN(chip->buf[6]); + dt->tm_year = BCD2BIN(chip->buf[7]); + + century = BCD2BIN(tmp) * 100; + + dt->tm_year += century; + dt->tm_year -= 1900; + +#ifdef MAX6902_DEBUG + printk("\n%s : Read RTC values\n",__FUNCTION__); + printk("tm_hour: %i\n",dt->tm_hour); + printk("tm_min : %i\n",dt->tm_min); + printk("tm_sec : %i\n",dt->tm_sec); + printk("tm_year: %i\n",dt->tm_year); + printk("tm_mon : %i\n",dt->tm_mon); + printk("tm_mday: %i\n",dt->tm_mday); + printk("tm_wday: %i\n",dt->tm_wday); +#endif + + return 0; +} + +static int max6902_set_datetime(struct device *dev, struct rtc_time *dt) +{ + dt->tm_year = dt->tm_year+1900; + +#ifdef MAX6902_DEBUG + printk("\n%s : Setting RTC values\n",__FUNCTION__); + printk("tm_sec : %i\n",dt->tm_sec); + printk("tm_min : %i\n",dt->tm_min); + printk("tm_hour: %i\n",dt->tm_hour); + printk("tm_mday: %i\n",dt->tm_mday); + printk("tm_wday: %i\n",dt->tm_wday); + printk("tm_year: %i\n",dt->tm_year); +#endif + + /* Remove write protection */ + max6902_set_reg(dev, 0xF, 0); + + max6902_set_reg(dev, 0x01, BIN2BCD(dt->tm_sec)); + max6902_set_reg(dev, 0x03, BIN2BCD(dt->tm_min)); + max6902_set_reg(dev, 0x05, BIN2BCD(dt->tm_hour)); + + max6902_set_reg(dev, 0x07, BIN2BCD(dt->tm_mday)); + max6902_set_reg(dev, 0x09, BIN2BCD(dt->tm_mon+1)); + max6902_set_reg(dev, 0x0B, BIN2BCD(dt->tm_wday)); + max6902_set_reg(dev, 0x0D, BIN2BCD(dt->tm_year%100)); + max6902_set_reg(dev, 0x13, BIN2BCD(dt->tm_year/100)); + + /* Compulab used a delay here. However, the datasheet + * does not mention a delay being required anywhere... */ + /* delay(2000); */ + + /* Write protect */ + max6902_set_reg(dev, 0xF, 0x80); + + return 0; +} + +static int max6902_read_time(struct device *dev, struct rtc_time *tm) +{ + return max6902_get_datetime(dev, tm); +} + +static int max6902_set_time(struct device *dev, struct rtc_time *tm) +{ + return max6902_set_datetime(dev, tm); +} + +static struct rtc_class_ops max6902_rtc_ops = { + .read_time = max6902_read_time, + .set_time = max6902_set_time, +}; + +static int __devinit max6902_probe(struct spi_device *spi) +{ + struct rtc_device *rtc; + unsigned char tmp; + struct max6902 *chip; + int res; + + rtc = rtc_device_register("max6902", + &spi->dev, &max6902_rtc_ops, THIS_MODULE); + if (IS_ERR(rtc)) + return PTR_ERR(rtc); + + spi->mode = SPI_MODE_3; + spi->bits_per_word = 8; + spi_setup(spi); + + chip = kzalloc(sizeof *chip, GFP_KERNEL); + if (!chip) { + rtc_device_unregister(rtc); + return -ENOMEM; + } + chip->rtc = rtc; + dev_set_drvdata(&spi->dev, chip); + + res = max6902_get_reg(&spi->dev, MAX6902_REG_SECONDS, &tmp); + if (res) { + rtc_device_unregister(rtc); + return res; + } + + return 0; +} + +static int __devexit max6902_remove(struct spi_device *spi) +{ + struct max6902 *chip = platform_get_drvdata(spi); + struct rtc_device *rtc = chip->rtc; + + if (rtc) + rtc_device_unregister(rtc); + + kfree(chip); + + return 0; +} + +static struct spi_driver max6902_driver = { + .driver = { + .name = "max6902", + .bus = &spi_bus_type, + .owner = THIS_MODULE, + }, + .probe = max6902_probe, + .remove = __devexit_p(max6902_remove), +}; + +static __init int max6902_init(void) +{ + printk("max6902 spi driver\n"); + return spi_register_driver(&max6902_driver); +} +module_init(max6902_init); + +static __exit void max6902_exit(void) +{ + spi_unregister_driver(&max6902_driver); +} +module_exit(max6902_exit); + +MODULE_DESCRIPTION ("max6902 spi RTC driver"); +MODULE_AUTHOR ("Raphael Assenat"); +MODULE_LICENSE ("GPL"); |