[PATCH] "RTC-framework" driver for DS1307 and similar RTC chips
David Brownell [Sun, 25 Jun 2006 12:48:17 +0000 (05:48 -0700)]
This is an "RTC-framework" driver for DS1307 and similar RTC chips,

It should be a full replacement for the existing ds1337.c driver (using the
older RTC glue), giving a net increase in the number of RTC chips that work
out-of-the-box.  There's a whole cluster of RTCs that are very similar, but
the 1337 driver was a bit too picky to work with most of them.

Still no support for RTC alarm IRQs (on chips that support them).

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: James Chapman <jchapman@katalix.com>
Signed-off-by: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

drivers/rtc/Kconfig
drivers/rtc/Makefile
drivers/rtc/rtc-ds1307.c [new file with mode: 0644]

index 875ff5e..9e24965 100644 (file)
@@ -86,6 +86,24 @@ config RTC_DRV_X1205
          This driver can also be built as a module. If so, the module
          will be called rtc-x1205.
 
+config RTC_DRV_DS1307
+       tristate "Dallas/Maxim DS1307 and similar I2C RTC chips"
+       depends on RTC_CLASS && I2C
+       help
+         If you say yes here you get support for various compatible RTC
+         chips (often with battery backup) connected with I2C.  This driver
+         should handle DS1307, DS1337, DS1338, DS1339, DS1340, ST M41T00,
+         and probably other chips.  In some cases the RTC must already
+         have been initialized (by manufacturing or a bootloader).
+
+         The first seven registers on these chips hold an RTC, and other
+         registers may add features such as NVRAM, a trickle charger for
+         the RTC/NVRAM backup power, and alarms.  This driver may not
+         expose all those available chip features.
+
+         This driver can also be built as a module. If so, the module
+         will be called rtc-ds1307.
+
 config RTC_DRV_DS1672
        tristate "Dallas/Maxim DS1672"
        depends on RTC_CLASS && I2C
index 1b3f32e..ca8bed5 100644 (file)
@@ -13,6 +13,7 @@ obj-$(CONFIG_RTC_INTF_DEV)    += rtc-dev.o
 
 obj-$(CONFIG_RTC_DRV_X1205)    += rtc-x1205.o
 obj-$(CONFIG_RTC_DRV_TEST)     += rtc-test.o
+obj-$(CONFIG_RTC_DRV_DS1307)   += rtc-ds1307.o
 obj-$(CONFIG_RTC_DRV_DS1672)   += rtc-ds1672.o
 obj-$(CONFIG_RTC_DRV_PCF8563)  += rtc-pcf8563.o
 obj-$(CONFIG_RTC_DRV_RS5C372)  += rtc-rs5c372.o
diff --git a/drivers/rtc/rtc-ds1307.c b/drivers/rtc/rtc-ds1307.c
new file mode 100644 (file)
index 0000000..e8afb93
--- /dev/null
@@ -0,0 +1,388 @@
+/*
+ * rtc-ds1307.c - RTC driver for some mostly-compatible I2C chips.
+ *
+ *  Copyright (C) 2005 James Chapman (ds1337 core)
+ *  Copyright (C) 2006 David Brownell
+ *
+ * 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/module.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/i2c.h>
+#include <linux/string.h>
+#include <linux/rtc.h>
+#include <linux/bcd.h>
+
+
+
+/* We can't determine type by probing, but if we expect pre-Linux code
+ * to have set the chip up as a clock (turning on the oscillator and
+ * setting the date and time), Linux can ignore the non-clock features.
+ * That's a natural job for a factory or repair bench.
+ *
+ * If the I2C "force" mechanism is used, we assume the chip is a ds1337.
+ * (Much better would be board-specific tables of I2C devices, along with
+ * the platform_data drivers would use to sort such issues out.)
+ */
+enum ds_type {
+       unknown = 0,
+       ds_1307,                /* or ds1338, ... */
+       ds_1337,                /* or ds1339, ... */
+       ds_1340,                /* or st m41t00, ... */
+       // rs5c372 too?  different address...
+};
+
+static unsigned short normal_i2c[] = { 0x68, I2C_CLIENT_END };
+
+I2C_CLIENT_INSMOD;
+
+
+
+/* RTC registers don't differ much, except for the century flag */
+#define DS1307_REG_SECS                0x00    /* 00-59 */
+#      define DS1307_BIT_CH            0x80
+#define DS1307_REG_MIN         0x01    /* 00-59 */
+#define DS1307_REG_HOUR                0x02    /* 00-23, or 1-12{am,pm} */
+#      define DS1340_BIT_CENTURY_EN    0x80    /* in REG_HOUR */
+#      define DS1340_BIT_CENTURY       0x40    /* in REG_HOUR */
+#define DS1307_REG_WDAY                0x03    /* 01-07 */
+#define DS1307_REG_MDAY                0x04    /* 01-31 */
+#define DS1307_REG_MONTH       0x05    /* 01-12 */
+#      define DS1337_BIT_CENTURY       0x80    /* in REG_MONTH */
+#define DS1307_REG_YEAR                0x06    /* 00-99 */
+
+/* Other registers (control, status, alarms, trickle charge, NVRAM, etc)
+ * start at 7, and they differ a lot. Only control and status matter for RTC;
+ * be careful using them.
+ */
+#define DS1307_REG_CONTROL     0x07
+#      define DS1307_BIT_OUT           0x80
+#      define DS1307_BIT_SQWE          0x10
+#      define DS1307_BIT_RS1           0x02
+#      define DS1307_BIT_RS0           0x01
+#define DS1337_REG_CONTROL     0x0e
+#      define DS1337_BIT_nEOSC         0x80
+#      define DS1337_BIT_RS2           0x10
+#      define DS1337_BIT_RS1           0x08
+#      define DS1337_BIT_INTCN         0x04
+#      define DS1337_BIT_A2IE          0x02
+#      define DS1337_BIT_A1IE          0x01
+#define DS1337_REG_STATUS      0x0f
+#      define DS1337_BIT_OSF           0x80
+#      define DS1337_BIT_A2I           0x02
+#      define DS1337_BIT_A1I           0x01
+#define DS1339_REG_TRICKLE     0x10
+
+
+
+struct ds1307 {
+       u8                      reg_addr;
+       u8                      regs[8];
+       enum ds_type            type;
+       struct i2c_msg          msg[2];
+       struct i2c_client       client;
+       struct rtc_device       *rtc;
+};
+
+
+static int ds1307_get_time(struct device *dev, struct rtc_time *t)
+{
+       struct ds1307   *ds1307 = dev_get_drvdata(dev);
+       int             tmp;
+
+       /* read the RTC registers all at once */
+       ds1307->msg[1].flags = I2C_M_RD;
+       ds1307->msg[1].len = 7;
+
+       tmp = i2c_transfer(ds1307->client.adapter, ds1307->msg, 2);
+       if (tmp != 2) {
+               dev_err(dev, "%s error %d\n", "read", tmp);
+               return -EIO;
+       }
+
+       dev_dbg(dev, "%s: %02x %02x %02x %02x %02x %02x %02x\n",
+                       "read",
+                       ds1307->regs[0], ds1307->regs[1],
+                       ds1307->regs[2], ds1307->regs[3],
+                       ds1307->regs[4], ds1307->regs[5],
+                       ds1307->regs[6]);
+
+       t->tm_sec = BCD2BIN(ds1307->regs[DS1307_REG_SECS] & 0x7f);
+       t->tm_min = BCD2BIN(ds1307->regs[DS1307_REG_MIN] & 0x7f);
+       tmp = ds1307->regs[DS1307_REG_HOUR] & 0x3f;
+       t->tm_hour = BCD2BIN(tmp);
+       t->tm_wday = BCD2BIN(ds1307->regs[DS1307_REG_WDAY] & 0x07) - 1;
+       t->tm_mday = BCD2BIN(ds1307->regs[DS1307_REG_MDAY] & 0x3f);
+       tmp = ds1307->regs[DS1307_REG_MONTH] & 0x1f;
+       t->tm_mon = BCD2BIN(tmp) - 1;
+
+       /* assume 20YY not 19YY, and ignore DS1337_BIT_CENTURY */
+       t->tm_year = BCD2BIN(ds1307->regs[DS1307_REG_YEAR]) + 100;
+
+       dev_dbg(dev, "%s secs=%d, mins=%d, "
+               "hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
+               "read", t->tm_sec, t->tm_min,
+               t->tm_hour, t->tm_mday,
+               t->tm_mon, t->tm_year, t->tm_wday);
+
+       return 0;
+}
+
+static int ds1307_set_time(struct device *dev, struct rtc_time *t)
+{
+       struct ds1307   *ds1307 = dev_get_drvdata(dev);
+       int             result;
+       int             tmp;
+       u8              *buf = ds1307->regs;
+
+       dev_dbg(dev, "%s secs=%d, mins=%d, "
+               "hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
+               "write", dt->tm_sec, dt->tm_min,
+               dt->tm_hour, dt->tm_mday,
+               dt->tm_mon, dt->tm_year, dt->tm_wday);
+
+       *buf++ = 0;             /* first register addr */
+       buf[DS1307_REG_SECS] = BIN2BCD(t->tm_sec);
+       buf[DS1307_REG_MIN] = BIN2BCD(t->tm_min);
+       buf[DS1307_REG_HOUR] = BIN2BCD(t->tm_hour);
+       buf[DS1307_REG_WDAY] = BIN2BCD(t->tm_wday + 1);
+       buf[DS1307_REG_MDAY] = BIN2BCD(t->tm_mday);
+       buf[DS1307_REG_MONTH] = BIN2BCD(t->tm_mon + 1);
+
+       /* assume 20YY not 19YY */
+       tmp = t->tm_year - 100;
+       buf[DS1307_REG_YEAR] = BIN2BCD(tmp);
+
+       if (ds1307->type == ds_1337)
+               buf[DS1307_REG_MONTH] |= DS1337_BIT_CENTURY;
+       else if (ds1307->type == ds_1340)
+               buf[DS1307_REG_HOUR] |= DS1340_BIT_CENTURY_EN
+                               | DS1340_BIT_CENTURY;
+
+       ds1307->msg[1].flags = 0;
+       ds1307->msg[1].len = 8;
+
+       dev_dbg(dev, "%s: %02x %02x %02x %02x %02x %02x %02x\n",
+               "write", buf[0], buf[1], buf[2], buf[3],
+               buf[4], buf[5], buf[6]);
+
+       result = i2c_transfer(ds1307->client.adapter, &ds1307->msg[1], 1);
+       if (result != 1) {
+               dev_err(dev, "%s error %d\n", "write", tmp);
+               return -EIO;
+       }
+       return 0;
+}
+
+static struct rtc_class_ops ds13xx_rtc_ops = {
+       .read_time      = ds1307_get_time,
+       .set_time       = ds1307_set_time,
+};
+
+static struct i2c_driver ds1307_driver;
+
+static int __devinit
+ds1307_detect(struct i2c_adapter *adapter, int address, int kind)
+{
+       struct ds1307           *ds1307;
+       int                     err = -ENODEV;
+       struct i2c_client       *client;
+       int                     tmp;
+
+       if (!(ds1307 = kzalloc(sizeof(struct ds1307), GFP_KERNEL))) {
+               err = -ENOMEM;
+               goto exit;
+       }
+
+       client = &ds1307->client;
+       client->addr = address;
+       client->adapter = adapter;
+       client->driver = &ds1307_driver;
+       client->flags = 0;
+
+       i2c_set_clientdata(client, ds1307);
+
+       ds1307->msg[0].addr = client->addr;
+       ds1307->msg[0].flags = 0;
+       ds1307->msg[0].len = 1;
+       ds1307->msg[0].buf = &ds1307->reg_addr;
+
+       ds1307->msg[1].addr = client->addr;
+       ds1307->msg[1].flags = I2C_M_RD;
+       ds1307->msg[1].len = sizeof(ds1307->regs);
+       ds1307->msg[1].buf = ds1307->regs;
+
+       /* HACK: "force" implies "needs ds1337-style-oscillator setup" */
+       if (kind >= 0) {
+               ds1307->type = ds_1337;
+
+               ds1307->reg_addr = DS1337_REG_CONTROL;
+               ds1307->msg[1].len = 2;
+
+               tmp = i2c_transfer(client->adapter, ds1307->msg, 2);
+               if (tmp != 2) {
+                       pr_debug("read error %d\n", tmp);
+                       err = -EIO;
+                       goto exit_free;
+               }
+
+               ds1307->reg_addr = 0;
+               ds1307->msg[1].len = sizeof(ds1307->regs);
+
+               /* oscillator is off; need to turn it on */
+               if ((ds1307->regs[0] & DS1337_BIT_nEOSC)
+                               || (ds1307->regs[1] & DS1337_BIT_OSF)) {
+                       printk(KERN_ERR "no ds1337 oscillator code\n");
+                       goto exit_free;
+               }
+       } else
+               ds1307->type = ds_1307;
+
+read_rtc:
+       /* read RTC registers */
+
+       tmp = i2c_transfer(client->adapter, ds1307->msg, 2);
+       if (tmp != 2) {
+               pr_debug("read error %d\n", tmp);
+               err = -EIO;
+               goto exit_free;
+       }
+
+       /* minimal sanity checking; some chips (like DS1340) don't
+        * specify the extra bits as must-be-zero, but there are
+        * still a few values that are clearly out-of-range.
+        */
+       tmp = ds1307->regs[DS1307_REG_SECS];
+       if (tmp & DS1307_BIT_CH) {
+               if (ds1307->type && ds1307->type != ds_1307) {
+                       pr_debug("not a ds1307?\n");
+                       goto exit_free;
+               }
+               ds1307->type = ds_1307;
+
+               /* this partial initialization should work for ds1307,
+                * ds1338, ds1340, st m41t00, and more.
+                */
+               dev_warn(&client->dev, "oscillator started; SET TIME!\n");
+               i2c_smbus_write_byte_data(client, 0, 0);
+               goto read_rtc;
+       }
+       tmp = BCD2BIN(tmp & 0x7f);
+       if (tmp > 60)
+               goto exit_free;
+       tmp = BCD2BIN(ds1307->regs[DS1307_REG_MIN] & 0x7f);
+       if (tmp > 60)
+               goto exit_free;
+
+       tmp = BCD2BIN(ds1307->regs[DS1307_REG_MDAY] & 0x3f);
+       if (tmp == 0 || tmp > 31)
+               goto exit_free;
+
+       tmp = BCD2BIN(ds1307->regs[DS1307_REG_MONTH] & 0x1f);
+       if (tmp == 0 || tmp > 12)
+               goto exit_free;
+
+       /* force into in 24 hour mode (most chips) or
+        * disable century bit (ds1340)
+        */
+       tmp = ds1307->regs[DS1307_REG_HOUR];
+       if (tmp & (1 << 6)) {
+               if (tmp & (1 << 5))
+                       tmp = BCD2BIN(tmp & 0x1f) + 12;
+               else
+                       tmp = BCD2BIN(tmp);
+               i2c_smbus_write_byte_data(client,
+                               DS1307_REG_HOUR,
+                               BIN2BCD(tmp));
+       }
+
+       /* FIXME chips like 1337 can generate alarm irqs too; those are
+        * worth exposing through the API (especially when the irq is
+        * wakeup-capable).
+        */
+
+       switch (ds1307->type) {
+       case unknown:
+               strlcpy(client->name, "unknown", I2C_NAME_SIZE);
+               break;
+       case ds_1307:
+               strlcpy(client->name, "ds1307", I2C_NAME_SIZE);
+               break;
+       case ds_1337:
+               strlcpy(client->name, "ds1337", I2C_NAME_SIZE);
+               break;
+       case ds_1340:
+               strlcpy(client->name, "ds1340", I2C_NAME_SIZE);
+               break;
+       }
+
+       /* Tell the I2C layer a new client has arrived */
+       if ((err = i2c_attach_client(client)))
+               goto exit_free;
+
+       ds1307->rtc = rtc_device_register(client->name, &client->dev,
+                               &ds13xx_rtc_ops, THIS_MODULE);
+       if (IS_ERR(ds1307->rtc)) {
+               err = PTR_ERR(ds1307->rtc);
+               dev_err(&client->dev,
+                       "unable to register the class device\n");
+               goto exit_detach;
+       }
+
+       return 0;
+
+exit_detach:
+       i2c_detach_client(client);
+exit_free:
+       kfree(ds1307);
+exit:
+       return err;
+}
+
+static int __devinit
+ds1307_attach_adapter(struct i2c_adapter *adapter)
+{
+       if (!i2c_check_functionality(adapter, I2C_FUNC_I2C))
+               return 0;
+       return i2c_probe(adapter, &addr_data, ds1307_detect);
+}
+
+static int __devexit ds1307_detach_client(struct i2c_client *client)
+{
+       int             err;
+       struct ds1307   *ds1307 = i2c_get_clientdata(client);
+
+       rtc_device_unregister(ds1307->rtc);
+       if ((err = i2c_detach_client(client)))
+               return err;
+       kfree(ds1307);
+       return 0;
+}
+
+static struct i2c_driver ds1307_driver = {
+       .driver = {
+               .name   = "ds1307",
+               .owner  = THIS_MODULE,
+       },
+       .attach_adapter = ds1307_attach_adapter,
+       .detach_client  = __devexit_p(ds1307_detach_client),
+};
+
+static int __init ds1307_init(void)
+{
+       return i2c_add_driver(&ds1307_driver);
+}
+module_init(ds1307_init);
+
+static void __exit ds1307_exit(void)
+{
+       i2c_del_driver(&ds1307_driver);
+}
+module_exit(ds1307_exit);
+
+MODULE_DESCRIPTION("RTC driver for DS1307 and similar chips");
+MODULE_LICENSE("GPL");