[PATCH] "RTC-framework" driver for DS1307 and similar RTC chips
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>
diff --git a/drivers/rtc/rtc-ds1307.c b/drivers/rtc/rtc-ds1307.c
new file mode 100644
index 0000000..e8afb93
--- /dev/null
+++ b/drivers/rtc/rtc-ds1307.c
@@ -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");