Re: [PATCH] 2.6 I2C epson 8564 RTC chip
From: Ian Campbell
Date: Thu Apr 29 2004 - 07:44:55 EST
Hi Stefan,
> This driver only does the low-level I2C stuff, the rtc misc device
> driver is a separate driver module which I will send a patch for soon.
I have a patch (attached, it could do with cleaning up) for the Dallas
DS1307 I2C RTC which I ported from the 2.4 rmk patch, originally written
by Intrinsyc. Currently it includes both the I2C and the RTC bits in the
same driver.
Do you think it is realistic/possible to have the same generic RTC
driver speak to multiple I2C devices, from what I can see in your driver
the two chips seem pretty similar and the differences could probably be
abstracted away. Perhaps that is your intention from the start?
I guess I will wait until you post the RTC misc driver and try and make
the DS1307 one work with that before I submit it.
Ian.
--
Ian Campbell, Senior Design Engineer
Web: http://www.arcom.com
Arcom, Clifton Road, Direct: +44 (0)1223 403 465
Cambridge CB1 7EA, United Kingdom Phone: +44 (0)1223 411 200
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This message has been virus scanned by MessageLabs.Index: linux-2.6-bkpxa/drivers/i2c/chips/Kconfig
===================================================================
--- linux-2.6-bkpxa.orig/drivers/i2c/chips/Kconfig 2004-04-26 11:00:40.000000000 +0100
+++ linux-2.6-bkpxa/drivers/i2c/chips/Kconfig 2004-04-26 11:03:03.000000000 +0100
@@ -230,4 +230,8 @@
This driver can also be built as a module. If so, the module
will be called pcf8591.
+config DS1307
+ tristate "Dallas Semiconductor DS1307 Real-Time Clock"
+ depends on I2C
+
endmenu
Index: linux-2.6-bkpxa/drivers/i2c/chips/Makefile
===================================================================
--- linux-2.6-bkpxa.orig/drivers/i2c/chips/Makefile 2004-04-26 11:00:40.000000000 +0100
+++ linux-2.6-bkpxa/drivers/i2c/chips/Makefile 2004-04-26 11:03:03.000000000 +0100
@@ -24,6 +24,8 @@
obj-$(CONFIG_SENSORS_VIA686A) += via686a.o
obj-$(CONFIG_SENSORS_W83L785TS) += w83l785ts.o
+obj-$(CONFIG_DS1307) += ds1307.o
+
ifeq ($(CONFIG_I2C_DEBUG_CHIP),y)
EXTRA_CFLAGS += -DDEBUG
endif
Index: linux-2.6-bkpxa/drivers/i2c/chips/ds1307.c
===================================================================
--- linux-2.6-bkpxa.orig/drivers/i2c/chips/ds1307.c 2004-04-26 09:37:12.000000000 +0100
+++ linux-2.6-bkpxa/drivers/i2c/chips/ds1307.c 2004-04-26 13:27:11.000000000 +0100
@@ -0,0 +1,602 @@
+/*
+ * ds1307.c
+ *
+ * Device driver for Dallas Semiconductor's Real Time Controller DS1307.
+ *
+ * Copyright (C) 2002 Intrinsyc Software Inc.
+ *
+ * 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/config.h>
+#include <linux/module.h>
+#include <linux/version.h>
+
+#include <linux/kernel.h>
+#include <linux/poll.h>
+#include <linux/i2c.h>
+#include <linux/slab.h>
+#include <linux/init.h>
+#include <linux/rtc.h>
+#include <linux/string.h>
+#include <linux/miscdevice.h>
+#include <linux/proc_fs.h>
+
+#include "ds1307.h"
+
+#if DEBUG
+static unsigned int rtc_debug = DEBUG;
+#else
+#define rtc_debug 0 /* gcc will remove all the debug code for us */
+#endif
+
+struct ds1307_data {
+ struct semaphore lock;
+ unsigned char control;
+};
+
+/* --- /dev/rtc interface --- */
+
+static struct i2c_client *rtc_client = NULL;
+
+static int ds1307_rtc_ioctl( struct inode *, struct file *, unsigned int, unsigned long);
+static int ds1307_rtc_open(struct inode *inode, struct file *file);
+static int ds1307_rtc_release(struct inode *inode, struct file *file);
+
+static struct file_operations rtc_fops = {
+ owner: THIS_MODULE,
+ ioctl: ds1307_rtc_ioctl,
+ open: ds1307_rtc_open,
+ release: ds1307_rtc_release,
+};
+
+static struct miscdevice ds1307_rtc_miscdev = {
+ RTC_MINOR,
+ "rtc",
+ &rtc_fops
+};
+
+
+static char *
+ds1307_mon2str( unsigned int mon)
+{
+ char *mon2str[12] = {
+ "Jan", "Feb", "Mar", "Apr", "May", "Jun",
+ "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
+ };
+ if( mon > 11) return "error";
+ else return mon2str[ mon];
+}
+
+static int
+ds1307_readram( char *buf, int len)
+{
+ struct i2c_client *client = rtc_client;
+ struct ds1307_data *data = i2c_get_clientdata(client);
+
+ unsigned long flags;
+ unsigned char ad[1] = { 0 };
+ int ret;
+ struct i2c_msg msgs[2] = {
+ { client->addr, 0, 1, ad },
+ { client->addr, I2C_M_RD, len, buf } };
+
+ spin_lock_irqsave(data->lock, flags);
+ ret = i2c_transfer(client->adapter, msgs, 2);
+ spin_unlock_irqrestore(data->lock,flags);
+
+ return ret;
+}
+
+static void
+ds1307_convert_to_time( struct rtc_time *dt, char *buf)
+{
+ dt->tm_sec = BCD_TO_BIN(buf[0]);
+ dt->tm_min = BCD_TO_BIN(buf[1]);
+
+ if ( TWELVE_HOUR_MODE(buf[2]) )
+ {
+ dt->tm_hour = HOURS_12(buf[2]);
+ if (HOURS_AP(buf[2])) /* PM */
+ {
+ dt->tm_hour += 12;
+ }
+ }
+ else /* 24-hour-mode */
+ {
+ dt->tm_hour = HOURS_24(buf[2]);
+ }
+
+ dt->tm_mday = BCD_TO_BIN(buf[4]);
+ /* dt->tm_mon is zero-based */
+ dt->tm_mon = BCD_TO_BIN(buf[5]) - 1;
+ /* year is 1900 + dt->tm_year */
+ dt->tm_year = BCD_TO_BIN(buf[6]) + 100;
+
+ if( rtc_debug > 2)
+ {
+ printk("ds1307_get_datetime: year = %d\n", dt->tm_year);
+ printk("ds1307_get_datetime: mon = %d\n", dt->tm_mon);
+ printk("ds1307_get_datetime: mday = %d\n", dt->tm_mday);
+ printk("ds1307_get_datetime: hour = %d\n", dt->tm_hour);
+ printk("ds1307_get_datetime: min = %d\n", dt->tm_min);
+ printk("ds1307_get_datetime: sec = %d\n", dt->tm_sec);
+ }
+}
+
+static int ds1307_rtc_proc_output( char *buf)
+{
+#define CHECK(ctrl,bit) ((ctrl & bit) ? "yes" : "no")
+ unsigned char ram[DS1307_RAM_SIZE];
+ int ret;
+
+ char *p = buf;
+
+ ret = ds1307_readram( ram, DS1307_RAM_SIZE);
+ if( ret > 0)
+ {
+ int i;
+ struct rtc_time dt;
+ char text[9];
+
+ p += sprintf(p, "DS1307 (64x8 Serial Real Time Clock)\n");
+
+ ds1307_convert_to_time( &dt, ram);
+ p += sprintf(p, "Date/Time : %02d-%s-%04d %02d:%02d:%02d\n",
+ dt.tm_mday, ds1307_mon2str(dt.tm_mon), dt.tm_year + 1900,
+ dt.tm_hour, dt.tm_min, dt.tm_sec);
+
+ p += sprintf(p, "Clock halted : %s\n", CHECK(ram[0],0x80));
+ p += sprintf(p, "24h mode : %s\n", CHECK(ram[2],0x40));
+ p += sprintf(p, "Square wave enabled : %s\n", CHECK(ram[7],0x10));
+ p += sprintf(p, "Freq : ");
+
+ switch( ram[7] & 0x03)
+ {
+ case RATE_1HZ:
+ p += sprintf(p, "1Hz\n");
+ break;
+ case RATE_4096HZ:
+ p += sprintf(p, "4.096kHz\n");
+ break;
+ case RATE_8192HZ:
+ p += sprintf(p, "8.192kHz\n");
+ break;
+ case RATE_32768HZ:
+ default:
+ p += sprintf(p, "32.768kHz\n");
+ break;
+
+ }
+
+ p += sprintf(p, "RAM dump:\n");
+ text[8]='\0';
+ for( i=0; i<DS1307_RAM_SIZE; i++)
+ {
+ p += sprintf(p, "%02X ", ram[i]);
+
+ if( (ram[i] < 32) || (ram[i]>126)) ram[i]='.';
+ text[i%8] = ram[i];
+ if( (i%8) == 7) p += sprintf(p, "%s\n",text);
+ }
+ p += sprintf(p, "\n");
+ }
+ else
+ {
+ p += sprintf(p, "Failed to read RTC memory!\n");
+ }
+
+ return p - buf;
+}
+
+static int ds1307_rtc_read_proc(char *page, char **start, off_t off,
+ int count, int *eof, void *data)
+{
+ int len = ds1307_rtc_proc_output (page);
+ if (len <= off+count) *eof = 1;
+ *start = page + off;
+ len -= off;
+ if (len>count) len = count;
+ if (len<0) len = 0;
+ return len;
+}
+
+/* --- I2C interface --- */
+// The DS1307 can only ever be present at address 0x68
+static unsigned short normal_i2c[] = { 0x68, I2C_CLIENT_END };
+static unsigned short normal_i2c_range[] = { I2C_CLIENT_END };
+
+I2C_CLIENT_INSMOD;
+
+static int ds1307_attach_adapter(struct i2c_adapter *adapter);
+static int ds1307_detect(struct i2c_adapter *adapter, int address, int kind);
+static void ds1307_init_client(struct i2c_client *client);
+static int ds1307_detach_client(struct i2c_client *client);
+static int ds1307_command(struct i2c_client *client, unsigned int cmd, void *arg);
+static void ds1307_enable_clock(struct i2c_client *client, int enable);
+
+struct i2c_driver ds1307_driver = {
+ .name = "ds1307",
+ .id = I2C_DRIVERID_DS1307,
+ .flags = I2C_DF_NOTIFY,
+ .attach_adapter = ds1307_attach_adapter,
+ .detach_client = ds1307_detach_client,
+ .command = ds1307_command
+};
+
+static int ds1307_id = 0;
+
+static void ds1307_init_client(struct i2c_client *client)
+{
+ struct ds1307_data *data = i2c_get_clientdata(client);
+ data->control = i2c_smbus_read_byte_data(client, 0x07);
+ ds1307_enable_clock(client, 1);
+}
+
+static int ds1307_attach_adapter(struct i2c_adapter *adapter)
+{
+ return i2c_probe(adapter, &addr_data, ds1307_detect);
+}
+
+/* The `kind' parameter contains 0 if this call is due to a `force'
+ parameter, and -1 otherwise */
+static int
+ds1307_detect(struct i2c_adapter *adapter, int address, int kind)
+{
+ struct i2c_client *new_client;
+ struct ds1307_data *data;
+ int err = 0;
+
+ if (!i2c_check_functionality(adapter,I2C_FUNC_SMBUS_WORD_DATA |
+ I2C_FUNC_SMBUS_WRITE_BYTE))
+ goto exit;
+
+ if ( kind < 0 ) {
+ if ( address != 0x68 ) /* DS1307 is always at address 0x68 */
+ goto exit;
+ }
+
+ /* OK. For now, we presume we have a valid client. We now create the
+ client structure. */
+ if (!(new_client = kmalloc(sizeof(struct i2c_client) +
+ sizeof(struct ds1307_data),
+ GFP_KERNEL))) {
+ err = -ENOMEM;
+ goto exit;
+ }
+ memset(new_client, 0, sizeof(struct i2c_client) +
+ sizeof(struct ds1307_data));
+ data = (struct ds1307_data *) (new_client + 1);
+ i2c_set_clientdata(new_client, data);
+ new_client->addr = address;
+ new_client->adapter = adapter;
+ new_client->driver = &ds1307_driver;
+ new_client->flags = 0;
+
+ /* Could do any remaing detection here -- if kind < 0 */
+
+ /* Fill in remaining client fields and put it into the global list */
+ strlcpy(new_client->name, "ds1307", I2C_NAME_SIZE);
+
+ new_client->id = ds1307_id++;
+ init_MUTEX(&data->lock);
+
+ /* Tell the I2C layer a new client has arrived */
+ if ((err = i2c_attach_client(new_client)))
+ goto exit_free;
+
+ /* Initialize the DS1307 chip */
+ ds1307_init_client(new_client);
+
+ rtc_client = new_client;
+
+ return 0;
+
+ exit_free:
+ kfree(new_client);
+ exit:
+ return err;
+}
+
+static int ds1307_detach_client(struct i2c_client *client)
+{
+ int err;
+
+ ds1307_enable_clock(client, 0);
+
+ if ((err = i2c_detach_client(client))) {
+ dev_err(&client->dev,
+ "ds1307.o: Client deregistration failed, client not detached.\n");
+ return err;
+ }
+
+ kfree(client);
+ return 0;
+}
+
+static __init int ds1307_init(void)
+{
+ int retval;
+
+ retval = i2c_add_driver(&ds1307_driver);
+ if (retval==0)
+ {
+ misc_register (&ds1307_rtc_miscdev);
+ create_proc_read_entry (PROC_DS1307_NAME, 0, 0, ds1307_rtc_read_proc, NULL);
+ printk(KERN_INFO "ds1307.o: RTC driver successfully loaded.\n");
+ }
+ return retval;
+}
+
+static __exit void ds1307_exit(void)
+{
+ remove_proc_entry (PROC_DS1307_NAME, NULL);
+ misc_deregister(&ds1307_rtc_miscdev);
+ i2c_del_driver(&ds1307_driver);
+}
+
+module_init(ds1307_init);
+module_exit(ds1307_exit);
+
+MODULE_AUTHOR ("Intrinsyc Software Inc.");
+MODULE_LICENSE("GPL");
+
+/* --- CUTOFF --- */
+
+static void ds1307_enable_clock(struct i2c_client *client, int enable)
+{
+ unsigned char ctrl_info;
+
+ if( enable)
+ ctrl_info = SQW_ENABLE | RATE_32768HZ;
+ else
+ ctrl_info = SQW_DISABLE;
+
+ ds1307_command(client, DS1307_SETCTRL, &ctrl_info);
+
+ /* read addr 0 (Clock-Halt bit and second counter) */
+ u32 reg = i2c_smbus_read_byte_data(client, 0x0);
+ if (enable)
+ reg &= ~CLOCK_HALT; /* clear Clock-Halt bit */
+ else
+ reg |= CLOCK_HALT; /* set Clock-Halt bit */
+ i2c_smbus_write_byte_data(client, 0, reg);
+}
+
+static int
+ds1307_get_datetime(struct i2c_client *client, struct rtc_time *dt)
+{
+ unsigned char buf[7], addr[1] = { 0 };
+ struct i2c_msg msgs[2] = {
+ { client->addr, 0, 1, addr },
+ { client->addr, I2C_M_RD, 7, buf }
+ };
+ int ret = -EIO;
+
+ memset(buf, 0, sizeof(buf));
+
+ ret = i2c_transfer(client->adapter, msgs, 2);
+
+ if (ret == 2) {
+ ds1307_convert_to_time( dt, buf);
+ ret = 0;
+ }
+ else
+ printk("ds1307_get_datetime(), i2c_transfer() returned %d\n",ret);
+
+ return ret;
+}
+
+static int
+ds1307_set_datetime(struct i2c_client *client, struct rtc_time *dt, int datetoo)
+{
+ unsigned char buf[8];
+ int ret, len = 4;
+
+ if( rtc_debug > 2)
+ {
+ printk("ds1307_set_datetime: tm_year = %d\n", dt->tm_year);
+ printk("ds1307_set_datetime: tm_mon = %d\n", dt->tm_mon);
+ printk("ds1307_set_datetime: tm_mday = %d\n", dt->tm_mday);
+ printk("ds1307_set_datetime: tm_hour = %d\n", dt->tm_hour);
+ printk("ds1307_set_datetime: tm_min = %d\n", dt->tm_min);
+ printk("ds1307_set_datetime: tm_sec = %d\n", dt->tm_sec);
+ }
+
+ buf[0] = 0; /* register address on DS1307 */
+ buf[1] = (BIN_TO_BCD(dt->tm_sec));
+ buf[2] = (BIN_TO_BCD(dt->tm_min));
+ buf[3] = (BIN_TO_BCD(dt->tm_hour));
+
+ if (datetoo) {
+ len = 8;
+ /* we skip buf[4] as we don't use day-of-week. */
+ buf[5] = (BIN_TO_BCD(dt->tm_mday));
+ buf[6] = (BIN_TO_BCD(dt->tm_mon + 1));
+ /* The year only ranges from 0-99, we are being passed an offset from 1900,
+ * and the chip calulates leap years based on 2000, thus we adjust by 100.
+ */
+ buf[7] = (BIN_TO_BCD(dt->tm_year - 100));
+ }
+ ret = i2c_master_send(client, (char *)buf, len);
+ if (ret == len)
+ ret = 0;
+ else
+ printk("ds1307_set_datetime(), i2c_master_send() returned %d\n",ret);
+
+ return ret;
+}
+
+static int
+ds1307_get_ctrl(struct i2c_client *client, unsigned char *ctrl)
+{
+ struct ds1307_data *data = i2c_get_clientdata(client);
+ *ctrl = data->control;
+ return 0;
+}
+
+static int
+ds1307_set_ctrl(struct i2c_client *client, unsigned char *cinfo)
+{
+ struct ds1307_data *data = i2c_get_clientdata(client);
+ data->control = *cinfo;
+ return i2c_smbus_write_byte_data(client, 0x07, data->control);
+}
+
+static int
+ds1307_read_mem(struct i2c_client *client, struct rtc_mem *mem)
+{
+ unsigned char addr[1];
+ struct i2c_msg msgs[2] = {
+ { client->addr, 0, 1, addr },
+ { client->addr, I2C_M_RD, mem->nr, mem->data }
+ };
+
+ if ( (mem->loc < DS1307_RAM_ADDR_START) ||
+ ((mem->loc + mem->nr -1) > DS1307_RAM_ADDR_END) )
+ return -EINVAL;
+
+ addr[0] = mem->loc;
+
+ return i2c_transfer(client->adapter, msgs, 2) == 2 ? 0 : -EIO;
+}
+
+static int
+ds1307_write_mem(struct i2c_client *client, struct rtc_mem *mem)
+{
+ unsigned char addr[1];
+ struct i2c_msg msgs[2] = {
+ { client->addr, 0, 1, addr },
+ { client->addr, 0, mem->nr, mem->data }
+ };
+
+ if ( (mem->loc < DS1307_RAM_ADDR_START) ||
+ ((mem->loc + mem->nr -1) > DS1307_RAM_ADDR_END) )
+ return -EINVAL;
+
+ addr[0] = mem->loc;
+
+ return i2c_transfer(client->adapter, msgs, 2) == 2 ? 0 : -EIO;
+}
+
+static int
+ds1307_command(struct i2c_client *client, unsigned int cmd, void *arg)
+{
+ switch (cmd) {
+ case DS1307_GETDATETIME:
+ return ds1307_get_datetime(client, arg);
+
+ case DS1307_SETTIME:
+ return ds1307_set_datetime(client, arg, 0);
+
+ case DS1307_SETDATETIME:
+ return ds1307_set_datetime(client, arg, 1);
+
+ case DS1307_GETCTRL:
+ return ds1307_get_ctrl(client, arg);
+
+ case DS1307_SETCTRL:
+ return ds1307_set_ctrl(client, arg);
+
+ case DS1307_MEM_READ:
+ return ds1307_read_mem(client, arg);
+
+ case DS1307_MEM_WRITE:
+ return ds1307_write_mem(client, arg);
+
+ default:
+ return -EINVAL;
+ }
+}
+
+static int
+ds1307_rtc_open(struct inode *inode, struct file *file)
+{
+ struct i2c_client *client = rtc_client;
+ struct ds1307_data *data;
+
+ if ( client == NULL )
+ return -ENODEV;
+
+ data = i2c_get_clientdata(client);
+
+ if ( data == NULL )
+ return -ENODEV;
+
+ /* re-read ctrl register to ensure there really is a device
+ * there. if we have a situation where the device is present
+ * but incorrectly connected (or just faulty) then we may seem
+ * to be reading/writing OK but really we are getting junk --
+ * so lets test that the CTRL register is really what we think
+ * it is. If it isn't then it is likely that we don't have a
+ * valid device attached */
+ u32 reg = i2c_smbus_read_byte_data(client, 0x07);
+
+ if ( reg == -1 ) {
+ printk (KERN_DEBUG "ds1307_rtc_open: could not verify ctrl - read returned %d.\n", reg);
+ return -ENODEV;
+ } else if ( (reg&~0x20) != (data->control&~0x20) ) { /* 0x20 is OSF bit, ignore it */
+ printk(KERN_DEBUG "ds1307_rtc_open: failed to verify ctrl register. "
+ "got 0x%02x wanted 0x%02x\n",
+ reg, data->control);
+ return -ENODEV;
+ }
+ return 0;
+}
+
+static int
+ds1307_rtc_release(struct inode *inode, struct file *file)
+{
+ return 0;
+}
+
+static int
+ds1307_rtc_ioctl( struct inode *inode, struct file *file,
+ unsigned int cmd, unsigned long arg)
+{
+ struct i2c_client *client = rtc_client;
+ struct ds1307_data *data = i2c_get_clientdata(client);
+
+ struct rtc_time wtime;
+
+ switch (cmd) {
+ default:
+ case RTC_UIE_ON:
+ case RTC_UIE_OFF:
+ case RTC_PIE_ON:
+ case RTC_PIE_OFF:
+ case RTC_AIE_ON:
+ case RTC_AIE_OFF:
+ case RTC_ALM_SET:
+ case RTC_ALM_READ:
+ case RTC_IRQP_READ:
+ case RTC_IRQP_SET:
+ case RTC_EPOCH_READ:
+ case RTC_EPOCH_SET:
+ case RTC_WKALM_SET:
+ case RTC_WKALM_RD:
+ return -EINVAL;
+
+ case RTC_RD_TIME:
+ down(&data->lock);
+ ds1307_command(client, DS1307_GETDATETIME, &wtime);
+ up(&data->lock);
+ if( copy_to_user((void *)arg, &wtime, sizeof (struct rtc_time)))
+ return -EFAULT;
+ return 0;
+
+ case RTC_SET_TIME:
+ if (!capable(CAP_SYS_TIME))
+ return -EACCES;
+ if (copy_from_user(&wtime, (struct rtc_time *)arg, sizeof(struct rtc_time)) )
+ return -EFAULT;
+
+ down(&data->lock);
+ ds1307_command(client, DS1307_SETDATETIME, &wtime);
+ up(&data->lock);
+ return 0;
+ }
+}
Index: linux-2.6-bkpxa/drivers/i2c/chips/ds1307.h
===================================================================
--- linux-2.6-bkpxa.orig/drivers/i2c/chips/ds1307.h 2004-04-26 09:37:12.000000000 +0100
+++ linux-2.6-bkpxa/drivers/i2c/chips/ds1307.h 2004-04-26 11:03:03.000000000 +0100
@@ -0,0 +1,52 @@
+/*
+ * ds1307.h
+ *
+ * Copyright (C) 2002 Intrinsyc Software Inc.
+ *
+ * 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.
+ *
+ */
+#ifndef DS1307_H
+#define DS1307_H
+
+#define DS1307_RAM_ADDR_START 0x08
+#define DS1307_RAM_ADDR_END 0x3F
+#define DS1307_RAM_SIZE 0x40
+
+#define PROC_DS1307_NAME "driver/ds1307"
+
+struct rtc_mem {
+ unsigned int loc;
+ unsigned int nr;
+ unsigned char *data;
+};
+
+#define DS1307_GETDATETIME 0
+#define DS1307_SETTIME 1
+#define DS1307_SETDATETIME 2
+#define DS1307_GETCTRL 3
+#define DS1307_SETCTRL 4
+#define DS1307_MEM_READ 5
+#define DS1307_MEM_WRITE 6
+
+#define SQW_ENABLE 0x10 /* Square Wave Enable */
+#define SQW_DISABLE 0x00 /* Square Wave disable */
+
+#define RATE_32768HZ 0x03 /* Rate Select 32.768KHz */
+#define RATE_8192HZ 0x02 /* Rate Select 8.192KHz */
+#define RATE_4096HZ 0x01 /* Rate Select 4.096KHz */
+#define RATE_1HZ 0x00 /* Rate Select 1Hz */
+
+#define CLOCK_HALT 0x80 /* Clock Halt */
+
+#define BCD_TO_BIN(val) (((val)&15) + ((val)>>4)*10)
+#define BIN_TO_BCD(val) ((((val)/10)<<4) + (val)%10)
+
+#define TWELVE_HOUR_MODE(n) (((n)>>6)&1)
+#define HOURS_AP(n) (((n)>>5)&1)
+#define HOURS_12(n) BCD_TO_BIN((n)&0x1F)
+#define HOURS_24(n) BCD_TO_BIN((n)&0x3F)
+
+#endif