i2c: New DS1682 chip driver

A driver for the Dallas DS1682 elapsed time recorder chip.

Tested on a MPC5200 based board using the integrated i2c adapter.

Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: Jean Delvare <khali@linux-fr.org>

1 files changed, 259 insertions, 0 deletions

diff --git a/drivers/i2c/chips/ds1682.c b/drivers/i2c/chips/ds1682.c
new file mode 100644
index 000000000000..25fd4676fb17
--- /dev/null
+++ b/drivers/i2c/chips/ds1682.c
@@ -0,0 +1,259 @@
+/*
+ * Dallas Semiconductor DS1682 Elapsed Time Recorder device driver
+ *
+ * Written by: Grant Likely <grant.likely@secretlab.ca>
+ *
+ * Copyright (C) 2007 Secret Lab Technologies 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.
+ */
+
+/*
+ * The DS1682 elapsed timer recorder is a simple device that implements
+ * one elapsed time counter, one event counter, an alarm signal and 10
+ * bytes of general purpose EEPROM.
+ *
+ * This driver provides access to the DS1682 counters and user data via
+ * the sysfs.  The following attributes are added to the device node:
+ *     elapsed_time (u32): Total elapsed event time in ms resolution
+ *     alarm_time (u32): When elapsed time exceeds the value in alarm_time,
+ *                       then the alarm pin is asserted.
+ *     event_count (u16): number of times the event pin has gone low.
+ *     eeprom (u8[10]): general purpose EEPROM
+ *
+ * Counter registers and user data are both read/write unless the device
+ * has been write protected.  This driver does not support turning off write
+ * protection.  Once write protection is turned on, it is impossible to
+ * turn it off again, so I have left the feature out of this driver to avoid
+ * accidental enabling, but it is trivial to add write protect support.
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/i2c.h>
+#include <linux/string.h>
+#include <linux/list.h>
+#include <linux/sysfs.h>
+#include <linux/ctype.h>
+#include <linux/hwmon-sysfs.h>
+
+/* Device registers */
+#define DS1682_REG_CONFIG               0x00
+#define DS1682_REG_ALARM                0x01
+#define DS1682_REG_ELAPSED              0x05
+#define DS1682_REG_EVT_CNTR             0x09
+#define DS1682_REG_EEPROM               0x0b
+#define DS1682_REG_RESET                0x1d
+#define DS1682_REG_WRITE_DISABLE        0x1e
+#define DS1682_REG_WRITE_MEM_DISABLE    0x1f
+
+#define DS1682_EEPROM_SIZE              10
+
+/*
+ * Generic counter attributes
+ */
+static ssize_t ds1682_show(struct device *dev, struct device_attribute *attr,
+                           char *buf)
+{
+        struct sensor_device_attribute_2 *sattr = to_sensor_dev_attr_2(attr);
+        struct i2c_client *client = to_i2c_client(dev);
+        __le32 val = 0;
+        int rc;
+
+        dev_dbg(dev, "ds1682_show() called on %s\n", attr->attr.name);
+
+        /* Read the register */
+        rc = i2c_smbus_read_i2c_block_data(client, sattr->index, sattr->nr,
+                                           (u8 *) & val);
+        if (rc < 0)
+                return -EIO;
+
+        /* Special case: the 32 bit regs are time values with 1/4s
+         * resolution, scale them up to milliseconds */
+        if (sattr->nr == 4)
+                return sprintf(buf, "%llu\n", ((u64) le32_to_cpu(val)) * 250);
+
+        /* Format the output string and return # of bytes */
+        return sprintf(buf, "%li\n", (long)le32_to_cpu(val));
+}
+
+static ssize_t ds1682_store(struct device *dev, struct device_attribute *attr,
+                            const char *buf, size_t count)
+{
+        struct sensor_device_attribute_2 *sattr = to_sensor_dev_attr_2(attr);
+        struct i2c_client *client = to_i2c_client(dev);
+        char *endp;
+        u64 val;
+        __le32 val_le;
+        int rc;
+
+        dev_dbg(dev, "ds1682_store() called on %s\n", attr->attr.name);
+
+        /* Decode input */
+        val = simple_strtoull(buf, &endp, 0);
+        if (buf == endp) {
+                dev_dbg(dev, "input string not a number\n");
+                return -EINVAL;
+        }
+
+        /* Special case: the 32 bit regs are time values with 1/4s
+         * resolution, scale input down to quarter-seconds */
+        if (sattr->nr == 4)
+                do_div(val, 250);
+
+        /* write out the value */
+        val_le = cpu_to_le32(val);
+        rc = i2c_smbus_write_i2c_block_data(client, sattr->index, sattr->nr,
+                                            (u8 *) & val_le);
+        if (rc < 0) {
+                dev_err(dev, "register write failed; reg=0x%x, size=%i\n",
+                        sattr->index, sattr->nr);
+                return -EIO;
+        }
+
+        return count;
+}
+
+/*
+ * Simple register attributes
+ */
+static SENSOR_DEVICE_ATTR_2(elapsed_time, S_IRUGO | S_IWUSR, ds1682_show,
+                            ds1682_store, 4, DS1682_REG_ELAPSED);
+static SENSOR_DEVICE_ATTR_2(alarm_time, S_IRUGO | S_IWUSR, ds1682_show,
+                            ds1682_store, 4, DS1682_REG_ALARM);
+static SENSOR_DEVICE_ATTR_2(event_count, S_IRUGO | S_IWUSR, ds1682_show,
+                            ds1682_store, 2, DS1682_REG_EVT_CNTR);
+
+static const struct attribute_group ds1682_group = {
+        .attrs = (struct attribute *[]) {
+                &sensor_dev_attr_elapsed_time.dev_attr.attr,
+                &sensor_dev_attr_alarm_time.dev_attr.attr,
+                &sensor_dev_attr_event_count.dev_attr.attr,
+                NULL,
+        },
+};
+
+/*
+ * User data attribute
+ */
+static ssize_t ds1682_eeprom_read(struct kobject *kobj, char *buf, loff_t off,
+                                  size_t count)
+{
+        struct i2c_client *client = kobj_to_i2c_client(kobj);
+        int rc;
+
+        dev_dbg(&client->dev, "ds1682_eeprom_read(p=%p, off=%lli, c=%zi)\n",
+                buf, off, count);
+
+        if (off >= DS1682_EEPROM_SIZE)
+                return 0;
+
+        if (off + count > DS1682_EEPROM_SIZE)
+                count = DS1682_EEPROM_SIZE - off;
+
+        rc = i2c_smbus_read_i2c_block_data(client, DS1682_REG_EEPROM + off,
+                                           count, buf);
+        if (rc < 0)
+                return -EIO;
+
+        return count;
+}
+
+static ssize_t ds1682_eeprom_write(struct kobject *kobj, char *buf, loff_t off,
+                                   size_t count)
+{
+        struct i2c_client *client = kobj_to_i2c_client(kobj);
+
+        dev_dbg(&client->dev, "ds1682_eeprom_write(p=%p, off=%lli, c=%zi)\n",
+                buf, off, count);
+
+        if (off >= DS1682_EEPROM_SIZE)
+                return -ENOSPC;
+
+        if (off + count > DS1682_EEPROM_SIZE)
+                count = DS1682_EEPROM_SIZE - off;
+
+        /* Write out to the device */
+        if (i2c_smbus_write_i2c_block_data(client, DS1682_REG_EEPROM + off,
+                                           count, buf) < 0)
+                return -EIO;
+
+        return count;
+}
+
+static struct bin_attribute ds1682_eeprom_attr = {
+        .attr = {
+                .name = "eeprom",
+                .mode = S_IRUGO | S_IWUSR,
+                .owner = THIS_MODULE,
+        },
+        .size = DS1682_EEPROM_SIZE,
+        .read = ds1682_eeprom_read,
+        .write = ds1682_eeprom_write,
+};
+
+/*
+ * Called when a ds1682 device is matched with this driver
+ */
+static int ds1682_probe(struct i2c_client *client)
+{
+        int rc;
+
+        if (!i2c_check_functionality(client->adapter,
+                                     I2C_FUNC_SMBUS_I2C_BLOCK)) {
+                dev_err(&client->dev, "i2c bus does not support the ds1682\n");
+                rc = -ENODEV;
+                goto exit;
+        }
+
+        rc = sysfs_create_group(&client->dev.kobj, &ds1682_group);
+        if (rc)
+                goto exit;
+
+        rc = sysfs_create_bin_file(&client->dev.kobj, &ds1682_eeprom_attr);
+        if (rc)
+                goto exit_bin_attr;
+
+        return 0;
+
+ exit_bin_attr:
+        sysfs_remove_group(&client->dev.kobj, &ds1682_group);
+ exit:
+        return rc;
+}
+
+static int ds1682_remove(struct i2c_client *client)
+{
+        sysfs_remove_bin_file(&client->dev.kobj, &ds1682_eeprom_attr);
+        sysfs_remove_group(&client->dev.kobj, &ds1682_group);
+        return 0;
+}
+
+static struct i2c_driver ds1682_driver = {
+        .driver = {
+                .name = "ds1682",
+        },
+        .probe = ds1682_probe,
+        .remove = ds1682_remove,
+};
+
+static int __init ds1682_init(void)
+{
+        return i2c_add_driver(&ds1682_driver);
+}
+
+static void __exit ds1682_exit(void)
+{
+        i2c_del_driver(&ds1682_driver);
+}
+
+MODULE_AUTHOR("Grant Likely <grant.likely@secretlab.ca>");
+MODULE_DESCRIPTION("DS1682 Elapsed Time Indicator driver");
+MODULE_LICENSE("GPL");
+
+module_init(ds1682_init);
+module_exit(ds1682_exit);