rtc: add device driver for Dallas DS3234 SPI RTC chip
Dennis Aberilla [Thu, 16 Oct 2008 05:02:57 +0000 (22:02 -0700)]
Add support for the Dallas DS3234 chip - extremely accurate SPI bus RTC
with integrated crystal and SRAM.

[akpm@linux-foundation.org: don't use BIN2BCD/BCD2BIN]
Signed-off-by: Dennis Aberilla <denzzzhome@yahoo.com>
Signed-off-by: Alessandro Zummo <a.zummo@towertech.it>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/rtc/Kconfig
drivers/rtc/Makefile
drivers/rtc/rtc-ds3234.c [new file with mode: 0644]

index f3d7fd3..16bc33c 100644 (file)
@@ -319,6 +319,15 @@ config RTC_DRV_RS5C348
          This driver can also be built as a module. If so, the module
          will be called rtc-rs5c348.
 
+config RTC_DRV_DS3234
+       tristate "Maxim/Dallas DS3234"
+       help
+         If you say yes here you get support for the
+         Maxim/Dallas DS3234 SPI RTC chip.
+
+         This driver can also be built as a module. If so, the module
+         will be called rtc-ds3234.
+
 endif # SPI_MASTER
 
 comment "Platform RTC drivers"
index 37a71b7..d05928b 100644 (file)
@@ -32,6 +32,7 @@ obj-$(CONFIG_RTC_DRV_DS1511)  += rtc-ds1511.o
 obj-$(CONFIG_RTC_DRV_DS1553)   += rtc-ds1553.o
 obj-$(CONFIG_RTC_DRV_DS1672)   += rtc-ds1672.o
 obj-$(CONFIG_RTC_DRV_DS1742)   += rtc-ds1742.o
+obj-$(CONFIG_RTC_DRV_DS3234)   += rtc-ds3234.o
 obj-$(CONFIG_RTC_DRV_EP93XX)   += rtc-ep93xx.o
 obj-$(CONFIG_RTC_DRV_FM3130)   += rtc-fm3130.o
 obj-$(CONFIG_RTC_DRV_ISL1208)  += rtc-isl1208.o
diff --git a/drivers/rtc/rtc-ds3234.c b/drivers/rtc/rtc-ds3234.c
new file mode 100644 (file)
index 0000000..37d131d
--- /dev/null
@@ -0,0 +1,290 @@
+/* drivers/rtc/rtc-ds3234.c
+ *
+ * Driver for Dallas Semiconductor (DS3234) SPI RTC with Integrated Crystal
+ * and SRAM.
+ *
+ * Copyright (C) 2008 MIMOMax Wireless 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.
+ *
+ * Changelog:
+ *
+ * 07-May-2008: Dennis Aberilla <denzzzhome@yahoo.com>
+ *             - Created based on the max6902 code. Only implements the
+ *               date/time keeping functions; no SRAM yet.
+ */
+
+#include <linux/device.h>
+#include <linux/platform_device.h>
+#include <linux/rtc.h>
+#include <linux/spi/spi.h>
+#include <linux/bcd.h>
+
+#define DS3234_REG_SECONDS     0x00
+#define DS3234_REG_MINUTES     0x01
+#define DS3234_REG_HOURS       0x02
+#define DS3234_REG_DAY         0x03
+#define DS3234_REG_DATE                0x04
+#define DS3234_REG_MONTH       0x05
+#define DS3234_REG_YEAR                0x06
+#define DS3234_REG_CENTURY     (1 << 7) /* Bit 7 of the Month register */
+
+#define DS3234_REG_CONTROL     0x0E
+#define DS3234_REG_CONT_STAT   0x0F
+
+#undef DS3234_DEBUG
+
+struct ds3234 {
+       struct rtc_device *rtc;
+       u8 buf[8]; /* Burst read: addr + 7 regs */
+       u8 tx_buf[2];
+       u8 rx_buf[2];
+};
+
+static void ds3234_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 '1' to indicate write */
+       buf[0] = address | 0x80;
+       buf[1] = data;
+
+       spi_write(spi, buf, 2);
+}
+
+static int ds3234_get_reg(struct device *dev, unsigned char address,
+                               unsigned char *data)
+{
+       struct spi_device *spi = to_spi_device(dev);
+       struct ds3234 *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));
+
+       /* Address + dummy tx byte */
+       xfer.len = 2;
+       xfer.tx_buf = chip->tx_buf;
+       xfer.rx_buf = chip->rx_buf;
+
+       chip->tx_buf[0] = address;
+       chip->tx_buf[1] = 0xff;
+
+       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 ds3234_get_datetime(struct device *dev, struct rtc_time *dt)
+{
+       struct spi_device *spi = to_spi_device(dev);
+       struct ds3234 *chip = dev_get_drvdata(dev);
+       struct spi_message message;
+       struct spi_transfer xfer;
+       int status;
+
+       /* build the message */
+       spi_message_init(&message);
+       memset(&xfer, 0, sizeof(xfer));
+       xfer.len = 1 + 7;       /* Addr + 7 registers */
+       xfer.tx_buf = chip->buf;
+       xfer.rx_buf = chip->buf;
+       chip->buf[0] = 0x00;    /* Start address */
+       spi_message_add_tail(&xfer, &message);
+
+       /* do the i/o */
+       status = spi_sync(spi, &message);
+       if (status == 0)
+               status = message.status;
+       else
+               return status;
+
+       /* Seconds, Minutes, Hours, Day, Date, Month, Year */
+       dt->tm_sec      = bcd2bin(chip->buf[1]);
+       dt->tm_min      = bcd2bin(chip->buf[2]);
+       dt->tm_hour     = bcd2bin(chip->buf[3] & 0x3f);
+       dt->tm_wday     = bcd2bin(chip->buf[4]) - 1; /* 0 = Sun */
+       dt->tm_mday     = bcd2bin(chip->buf[5]);
+       dt->tm_mon      = bcd2bin(chip->buf[6] & 0x1f) - 1; /* 0 = Jan */
+       dt->tm_year     = bcd2bin(chip->buf[7] & 0xff) + 100; /* Assume 20YY */
+
+#ifdef DS3234_DEBUG
+       dev_dbg(dev, "\n%s : Read RTC values\n", __func__);
+       dev_dbg(dev, "tm_hour: %i\n", dt->tm_hour);
+       dev_dbg(dev, "tm_min : %i\n", dt->tm_min);
+       dev_dbg(dev, "tm_sec : %i\n", dt->tm_sec);
+       dev_dbg(dev, "tm_wday: %i\n", dt->tm_wday);
+       dev_dbg(dev, "tm_mday: %i\n", dt->tm_mday);
+       dev_dbg(dev, "tm_mon : %i\n", dt->tm_mon);
+       dev_dbg(dev, "tm_year: %i\n", dt->tm_year);
+#endif
+
+       return 0;
+}
+
+static int ds3234_set_datetime(struct device *dev, struct rtc_time *dt)
+{
+#ifdef DS3234_DEBUG
+       dev_dbg(dev, "\n%s : Setting RTC values\n", __func__);
+       dev_dbg(dev, "tm_sec : %i\n", dt->tm_sec);
+       dev_dbg(dev, "tm_min : %i\n", dt->tm_min);
+       dev_dbg(dev, "tm_hour: %i\n", dt->tm_hour);
+       dev_dbg(dev, "tm_wday: %i\n", dt->tm_wday);
+       dev_dbg(dev, "tm_mday: %i\n", dt->tm_mday);
+       dev_dbg(dev, "tm_mon : %i\n", dt->tm_mon);
+       dev_dbg(dev, "tm_year: %i\n", dt->tm_year);
+#endif
+
+       ds3234_set_reg(dev, DS3234_REG_SECONDS, bin2bcd(dt->tm_sec));
+       ds3234_set_reg(dev, DS3234_REG_MINUTES, bin2bcd(dt->tm_min));
+       ds3234_set_reg(dev, DS3234_REG_HOURS, bin2bcd(dt->tm_hour) & 0x3f);
+
+       /* 0 = Sun */
+       ds3234_set_reg(dev, DS3234_REG_DAY, bin2bcd(dt->tm_wday + 1));
+       ds3234_set_reg(dev, DS3234_REG_DATE, bin2bcd(dt->tm_mday));
+
+       /* 0 = Jan */
+       ds3234_set_reg(dev, DS3234_REG_MONTH, bin2bcd(dt->tm_mon + 1));
+
+       /* Assume 20YY although we just want to make sure not to go negative. */
+       if (dt->tm_year > 100)
+               dt->tm_year -= 100;
+
+       ds3234_set_reg(dev, DS3234_REG_YEAR, bin2bcd(dt->tm_year));
+
+       return 0;
+}
+
+static int ds3234_read_time(struct device *dev, struct rtc_time *tm)
+{
+       return ds3234_get_datetime(dev, tm);
+}
+
+static int ds3234_set_time(struct device *dev, struct rtc_time *tm)
+{
+       return ds3234_set_datetime(dev, tm);
+}
+
+static const struct rtc_class_ops ds3234_rtc_ops = {
+       .read_time      = ds3234_read_time,
+       .set_time       = ds3234_set_time,
+};
+
+static int ds3234_probe(struct spi_device *spi)
+{
+       struct rtc_device *rtc;
+       unsigned char tmp;
+       struct ds3234 *chip;
+       int res;
+
+       rtc = rtc_device_register("ds3234",
+                               &spi->dev, &ds3234_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(struct ds3234), GFP_KERNEL);
+       if (!chip) {
+               rtc_device_unregister(rtc);
+               return -ENOMEM;
+       }
+       chip->rtc = rtc;
+       dev_set_drvdata(&spi->dev, chip);
+
+       res = ds3234_get_reg(&spi->dev, DS3234_REG_SECONDS, &tmp);
+       if (res) {
+               rtc_device_unregister(rtc);
+               return res;
+       }
+
+       /* Control settings
+        *
+        * CONTROL_REG
+        * BIT 7        6       5       4       3       2       1       0
+        *     EOSC     BBSQW   CONV    RS2     RS1     INTCN   A2IE    A1IE
+        *
+        *     0        0       0       1       1       1       0       0
+        *
+        * CONTROL_STAT_REG
+        * BIT 7        6       5       4       3       2       1       0
+        *     OSF      BB32kHz CRATE1  CRATE0  EN32kHz BSY     A2F     A1F
+        *
+        *     1        0       0       0       1       0       0       0
+        */
+       ds3234_get_reg(&spi->dev, DS3234_REG_CONTROL, &tmp);
+       ds3234_set_reg(&spi->dev, DS3234_REG_CONTROL, tmp & 0x1c);
+
+       ds3234_get_reg(&spi->dev, DS3234_REG_CONT_STAT, &tmp);
+       ds3234_set_reg(&spi->dev, DS3234_REG_CONT_STAT, tmp & 0x88);
+
+       /* Print our settings */
+       ds3234_get_reg(&spi->dev, DS3234_REG_CONTROL, &tmp);
+       dev_info(&spi->dev, "Control Reg: 0x%02x\n", tmp);
+
+       ds3234_get_reg(&spi->dev, DS3234_REG_CONT_STAT, &tmp);
+       dev_info(&spi->dev, "Ctrl/Stat Reg: 0x%02x\n", tmp);
+
+       return 0;
+}
+
+static int __exit ds3234_remove(struct spi_device *spi)
+{
+       struct ds3234 *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 ds3234_driver = {
+       .driver = {
+               .name    = "ds3234",
+               .bus    = &spi_bus_type,
+               .owner  = THIS_MODULE,
+       },
+       .probe   = ds3234_probe,
+       .remove = __devexit_p(ds3234_remove),
+};
+
+static __init int ds3234_init(void)
+{
+       printk(KERN_INFO "DS3234 SPI RTC Driver\n");
+       return spi_register_driver(&ds3234_driver);
+}
+module_init(ds3234_init);
+
+static __exit void ds3234_exit(void)
+{
+       spi_unregister_driver(&ds3234_driver);
+}
+module_exit(ds3234_exit);
+
+MODULE_DESCRIPTION("DS3234 SPI RTC driver");
+MODULE_AUTHOR("Dennis Aberilla <denzzzhome@yahoo.com>");
+MODULE_LICENSE("GPL");