[PATCH] I2C: New chip driver: ds1621

The following patch against kernel 2.6.4-mm1 adds the ds1621 driver (an
I2C sensor). I have ported it from the 2.4 version.

It has been reviewed by Jean Delvare, partly on IRC, and it is
"compliant" with Mark Hoffman's refactoring.

drivers/i2c/chips/Kconfig

@@ -33,6 +33,17 @@ config SENSORS_ASB100
 	  This driver can also be built as a module.  If so, the module
 	  will be called asb100.
 
+config SENSORS_DS1621
+      	tristate "Dallas Semiconductor DS1621 and DS1625"
+	depends on I2C && EXPERIMENTAL
+	select I2C_SENSOR
+	help
+	  If you say yes here you get support for Dallas Semiconductor
+	  DS1621 and DS1625 sensor chips. 
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called ds1621.
+
 config SENSORS_FSCHER
 	tristate "FSC Hermes"
 	depends on I2C && EXPERIMENTAL

drivers/i2c/chips/Makefile

@@ -8,6 +8,7 @@ obj-$(CONFIG_SENSORS_W83627HF)	+= w83627hf.o
 obj-$(CONFIG_SENSORS_W83781D)	+= w83781d.o
 
 obj-$(CONFIG_SENSORS_ADM1021)	+= adm1021.o
+obj-$(CONFIG_SENSORS_DS1621)	+= ds1621.o
 obj-$(CONFIG_SENSORS_EEPROM)	+= eeprom.o
 obj-$(CONFIG_SENSORS_FSCHER)	+= fscher.o
 obj-$(CONFIG_SENSORS_GL518SM)	+= gl518sm.o

drivers/i2c/chips/ds1621.c

+/*
+    ds1621.c - Part of lm_sensors, Linux kernel modules for hardware
+             monitoring
+    Christian W. Zuckschwerdt  <zany@triq.net>  2000-11-23
+    based on lm75.c by Frodo Looijaard <frodol@dds.nl>
+    Ported to Linux 2.6 by Aurelien Jarno <aurelien@aurel32.net> with 
+    the help of Jean Delvare <khali@linux-fr.org>
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program; if not, write to the Free Software
+    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+*/
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/i2c.h>
+#include <linux/i2c-sensor.h>
+#include "lm75.h"
+
+/* Addresses to scan */
+static unsigned short normal_i2c[] = { I2C_CLIENT_END };
+static unsigned short normal_i2c_range[] = { 0x48, 0x4f, I2C_CLIENT_END };
+static unsigned int normal_isa[] = { I2C_CLIENT_ISA_END };
+static unsigned int normal_isa_range[] = { I2C_CLIENT_ISA_END };
+
+/* Insmod parameters */
+SENSORS_INSMOD_1(ds1621);
+static int polarity = -1;
+MODULE_PARM(polarity, "i");
+MODULE_PARM_DESC(polarity, "Output's polarity: 0 = active high, 1 = active low");
+
+/* Many DS1621 constants specified below */
+/* Config register used for detection         */
+/*  7    6    5    4    3    2    1    0      */
+/* |Done|THF |TLF |NVB | 1  | 0  |POL |1SHOT| */
+#define DS1621_REG_CONFIG_MASK		0x0C
+#define DS1621_REG_CONFIG_VAL		0x08
+#define DS1621_REG_CONFIG_POLARITY	0x02
+#define DS1621_REG_CONFIG_1SHOT		0x01
+#define DS1621_REG_CONFIG_DONE		0x80
+
+/* The DS1621 registers */
+#define DS1621_REG_TEMP			0xAA /* word, RO */
+#define DS1621_REG_TEMP_MIN		0xA1 /* word, RW */
+#define DS1621_REG_TEMP_MAX		0xA2 /* word, RW */
+#define DS1621_REG_CONF			0xAC /* byte, RW */
+#define DS1621_COM_START		0xEE /* no data */
+
+/* The DS1621 configuration register */
+#define DS1621_ALARM_TEMP_HIGH		0x40
+#define DS1621_ALARM_TEMP_LOW		0x20
+
+/* Conversions. Rounding and limit checking is only done on the TO_REG
+   variants. Note that you should be a bit careful with which arguments
+   these macros are called: arguments may be evaluated more than once.
+   Fixing this is just not worth it. */
+#define ALARMS_FROM_REG(val) ((val) & \
+                              (DS1621_ALARM_TEMP_HIGH | DS1621_ALARM_TEMP_LOW))
+
+/* Each client has this additional data */
+struct ds1621_data {
+	struct semaphore update_lock;
+	char valid;			/* !=0 if following fields are valid */
+	unsigned long last_updated;	/* In jiffies */
+
+	u16 temp, temp_min, temp_max;	/* Register values, word */
+	u8 conf;			/* Register encoding, combined */
+};
+
+static int ds1621_attach_adapter(struct i2c_adapter *adapter);
+static int ds1621_detect(struct i2c_adapter *adapter, int address,
+			 int kind);
+static void ds1621_init_client(struct i2c_client *client);
+static int ds1621_detach_client(struct i2c_client *client);
+static struct ds1621_data *ds1621_update_client(struct device *dev);
+
+/* This is the driver that will be inserted */
+static struct i2c_driver ds1621_driver = {
+	.owner		= THIS_MODULE,
+	.name		= "ds1621",
+	.id		= I2C_DRIVERID_DS1621,
+	.flags		= I2C_DF_NOTIFY,
+	.attach_adapter	= ds1621_attach_adapter,
+	.detach_client	= ds1621_detach_client,
+};
+
+static int ds1621_id = 0;
+
+static u16 swap_bytes(u16 val)
+{
+	return (val >> 8) | (val << 8);
+}
+
+/* All registers are word-sized, except for the configuration register.
+   DS1621 uses a high-byte first convention, which is exactly opposite to
+   the usual practice. */
+static int ds1621_read_value(struct i2c_client *client, u8 reg)
+{
+	if (reg == DS1621_REG_CONF)
+		return i2c_smbus_read_byte_data(client, reg);
+	else
+		return swap_bytes(i2c_smbus_read_word_data(client, reg));
+}
+
+/* All registers are word-sized, except for the configuration register.
+   DS1621 uses a high-byte first convention, which is exactly opposite to
+   the usual practice. */
+static int ds1621_write_value(struct i2c_client *client, u8 reg, u16 value)
+{
+	if (reg == DS1621_REG_CONF)
+		return i2c_smbus_write_byte_data(client, reg, value);
+	else
+		return i2c_smbus_write_word_data(client, reg,
+						 swap_bytes(value));
+}
+
+static void ds1621_init_client(struct i2c_client *client)
+{
+	int reg = ds1621_read_value(client, DS1621_REG_CONF);
+	/* switch to continous conversion mode */
+	reg &= ~ DS1621_REG_CONFIG_1SHOT;
+
+	/* setup output polarity */
+	if (polarity == 0)
+		reg &= ~DS1621_REG_CONFIG_POLARITY;
+	else if (polarity == 1)
+		reg |= DS1621_REG_CONFIG_POLARITY;
+	
+	ds1621_write_value(client, DS1621_REG_CONF, reg);
+	
+	/* start conversion */
+	i2c_smbus_write_byte(client, DS1621_COM_START);
+}
+
+#define show(value)							\
+static ssize_t show_##value(struct device *dev, char *buf)		\
+{									\
+	struct ds1621_data *data = ds1621_update_client(dev);		\
+	return sprintf(buf, "%d\n", LM75_TEMP_FROM_REG(data->value));	\
+}
+
+show(temp);
+show(temp_min);
+show(temp_max);
+
+#define set_temp(suffix, value, reg)					\
+static ssize_t set_temp_##suffix(struct device *dev, const char *buf,	\
+				 size_t count)				\
+{									\
+	struct i2c_client *client = to_i2c_client(dev);			\
+	struct ds1621_data *data = ds1621_update_client(dev);		\
+	data->value = LM75_TEMP_TO_REG(simple_strtoul(buf, NULL, 10));	\
+	ds1621_write_value(client, reg, data->value);			\
+	return count;							\
+}
+
+set_temp(min, temp_min, DS1621_REG_TEMP_MIN);
+set_temp(max, temp_max, DS1621_REG_TEMP_MAX);
+
+static ssize_t show_alarms(struct device *dev, char *buf)
+{
+	struct ds1621_data *data = ds1621_update_client(dev);
+	return sprintf(buf, "%d\n", ALARMS_FROM_REG(data->conf));
+}
+
+static DEVICE_ATTR(alarms, S_IRUGO, show_alarms, NULL);
+static DEVICE_ATTR(temp1_input, S_IRUGO , show_temp, NULL);
+static DEVICE_ATTR(temp1_min, S_IWUSR | S_IRUGO , show_temp_min, set_temp_min);
+static DEVICE_ATTR(temp1_max, S_IWUSR | S_IRUGO, show_temp_max, set_temp_max);
+
+
+static int ds1621_attach_adapter(struct i2c_adapter *adapter)
+{
+	return i2c_detect(adapter, &addr_data, ds1621_detect);
+}
+
+/* This function is called by i2c_detect */
+int ds1621_detect(struct i2c_adapter *adapter, int address,
+                  int kind)
+{
+	int conf, temp;
+	struct i2c_client *new_client;
+	struct ds1621_data *data;
+	int err = 0;
+
+	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA 
+				     | I2C_FUNC_SMBUS_WORD_DATA 
+				     | I2C_FUNC_SMBUS_WRITE_BYTE))
+		goto exit;
+
+	/* OK. For now, we presume we have a valid client. We now create the
+	   client structure, even though we cannot fill it completely yet.
+	   But it allows us to access ds1621_{read,write}_value. */
+	if (!(new_client = kmalloc(sizeof(struct i2c_client) +
+				   sizeof(struct ds1621_data),
+				   GFP_KERNEL))) {
+		err = -ENOMEM;
+		goto exit;
+	}
+	memset(new_client, 0, sizeof(struct i2c_client) +
+	       sizeof(struct ds1621_data));
+	
+	data = (struct ds1621_data *) (new_client + 1);
+	i2c_set_clientdata(new_client, data);
+	new_client->addr = address;
+	new_client->adapter = adapter;
+	new_client->driver = &ds1621_driver;
+	new_client->flags = 0;
+
+
+	/* Now, we do the remaining detection. It is lousy. */
+	if (kind < 0) {
+		conf = ds1621_read_value(new_client, DS1621_REG_CONF);
+		if ((conf & DS1621_REG_CONFIG_MASK) != DS1621_REG_CONFIG_VAL)
+			goto exit_free;
+		temp = ds1621_read_value(new_client, DS1621_REG_TEMP);
+		if (temp & 0x007f)
+			goto exit_free;
+		temp = ds1621_read_value(new_client, DS1621_REG_TEMP_MIN);
+		if (temp & 0x007f)
+			goto exit_free;
+		temp = ds1621_read_value(new_client, DS1621_REG_TEMP_MAX);
+		if (temp & 0x007f)
+			goto exit_free;
+	}
+
+	/* Determine the chip type - only one kind supported! */
+	if (kind <= 0)
+		kind = ds1621;
+
+	/* Fill in remaining client fields and put it into the global list */
+	strlcpy(new_client->name, "ds1621", I2C_NAME_SIZE);
+
+	new_client->id = ds1621_id++;
+	data->valid = 0;
+	init_MUTEX(&data->update_lock);
+
+	/* Tell the I2C layer a new client has arrived */
+	if ((err = i2c_attach_client(new_client)))
+		goto exit_free;
+
+	/* Initialize the DS1621 chip */
+	ds1621_init_client(new_client);
+
+	/* Register sysfs hooks */
+	device_create_file(&new_client->dev, &dev_attr_alarms);
+	device_create_file(&new_client->dev, &dev_attr_temp1_input);
+	device_create_file(&new_client->dev, &dev_attr_temp1_min);
+	device_create_file(&new_client->dev, &dev_attr_temp1_max);
+	
+	return 0;
+
+/* OK, this is not exactly good programming practice, usually. But it is
+   very code-efficient in this case. */
+      exit_free:
+	kfree(new_client);
+      exit:
+	return err;
+}
+
+static int ds1621_detach_client(struct i2c_client *client)
+{
+	int err;
+
+	if ((err = i2c_detach_client(client))) {
+		dev_err(&client->dev,
+		        "ds1621.o: Client deregistration failed, client not detached.\n");
+		return err;
+	}
+
+	kfree(client);
+
+	return 0;
+}
+
+
+static struct ds1621_data *ds1621_update_client(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct ds1621_data *data = i2c_get_clientdata(client);
+	u8 new_conf;
+
+	down(&data->update_lock);
+
+	if ((jiffies - data->last_updated > HZ + HZ / 2) ||
+	    (jiffies < data->last_updated) || !data->valid) {
+
+		dev_dbg(&client->dev, "Starting ds1621 update\n");
+
+		data->conf = ds1621_read_value(client, DS1621_REG_CONF);
+
+		data->temp = ds1621_read_value(client, DS1621_REG_TEMP);
+		
+		data->temp_min = ds1621_read_value(client,
+		                                    DS1621_REG_TEMP_MIN);
+		data->temp_max = ds1621_read_value(client,
+						    DS1621_REG_TEMP_MAX);
+
+		/* reset alarms if neccessary */
+		new_conf = data->conf;
+		if (data->temp < data->temp_min)
+			new_conf &= ~DS1621_ALARM_TEMP_LOW;
+		if (data->temp > data->temp_max)
+			new_conf &= ~DS1621_ALARM_TEMP_HIGH;
+		if (data->conf != new_conf)
+			ds1621_write_value(client, DS1621_REG_CONF,
+					   new_conf);
+
+		data->last_updated = jiffies;
+		data->valid = 1;
+	}
+
+	up(&data->update_lock);
+
+	return data;
+}
+
+static int __init ds1621_init(void)
+{
+	return i2c_add_driver(&ds1621_driver);
+}
+
+static void __exit ds1621_exit(void)
+{
+	i2c_del_driver(&ds1621_driver);
+}
+
+
+MODULE_AUTHOR("Christian W. Zuckschwerdt <zany@triq.net>");
+MODULE_DESCRIPTION("DS1621 driver");
+MODULE_LICENSE("GPL");
+
+module_init(ds1621_init);
+module_exit(ds1621_exit);