[PATCH] I2C: Add support for LM77

This patch (against the current stack) adds support for the
LM77 sensor chips made by National Semiconductor. Formerly
this was claimed by the LM75 driver but when I got hold of an
embedded board (built around the National Geode SC1100 CPU),
which was equipped with an LM77, it turned out that the two
chips are not compatible.

It has been developed with help of, reviewed and approved
by Jean Delvare.
Signed-off-by: Andras Bali <drewie@freemail.hu>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>

drivers/i2c/chips/Kconfig

@@ -99,6 +99,17 @@ config SENSORS_LM75
 	  This driver can also be built as a module.  If so, the module
 	  will be called lm75.
 
+config SENSORS_LM77
+	tristate "National Semiconductor LM77"
+	depends on I2C && EXPERIMENTAL
+	select I2C_SENSOR
+	help
+	  If you say yes here you get support for National Semiconductor LM77
+	  sensor chips.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called lm77.
+
 config SENSORS_LM78
 	tristate "National Semiconductor LM78 and compatibles"
 	depends on I2C && EXPERIMENTAL

drivers/i2c/chips/Makefile

@@ -15,6 +15,7 @@ obj-$(CONFIG_SENSORS_FSCHER)	+= fscher.o
 obj-$(CONFIG_SENSORS_GL518SM)	+= gl518sm.o
 obj-$(CONFIG_SENSORS_IT87)	+= it87.o
 obj-$(CONFIG_SENSORS_LM75)	+= lm75.o
+obj-$(CONFIG_SENSORS_LM77)	+= lm77.o
 obj-$(CONFIG_SENSORS_LM78)	+= lm78.o
 obj-$(CONFIG_SENSORS_LM80)	+= lm80.o
 obj-$(CONFIG_SENSORS_LM83)	+= lm83.o

drivers/i2c/chips/lm77.c

+/*
+    lm77.c - Part of lm_sensors, Linux kernel modules for hardware
+             monitoring
+
+    Copyright (c) 2004  Andras BALI <drewie@freemail.hu>
+
+    Heavily based on lm75.c by Frodo Looijaard <frodol@dds.nl>.  The LM77
+    is a temperature sensor and thermal window comparator with 0.5 deg
+    resolution made by National Semiconductor.  Complete datasheet can be
+    obtained at their site:
+       http://www.national.com/pf/LM/LM77.html
+
+    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/config.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/i2c.h>
+#include <linux/i2c-sensor.h>
+
+
+/* Addresses to scan */
+static unsigned short normal_i2c[] = { I2C_CLIENT_END };
+static unsigned short normal_i2c_range[] = { 0x48, 0x4b, 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(lm77);
+
+/* The LM77 registers */
+#define LM77_REG_TEMP		0x00
+#define LM77_REG_CONF		0x01
+#define LM77_REG_TEMP_HYST	0x02
+#define LM77_REG_TEMP_CRIT	0x03
+#define LM77_REG_TEMP_MIN	0x04
+#define LM77_REG_TEMP_MAX	0x05
+
+/* Each client has this additional data */
+struct lm77_data {
+	struct i2c_client	client;
+	struct semaphore	update_lock;
+	char			valid;
+	unsigned long		last_updated;	/* In jiffies */
+	int			temp_input;	/* Temperatures */
+	int			temp_crit;
+	int			temp_min;
+	int			temp_max;
+	int			temp_hyst;
+	u8			alarms;
+};
+
+static int lm77_attach_adapter(struct i2c_adapter *adapter);
+static int lm77_detect(struct i2c_adapter *adapter, int address, int kind);
+static void lm77_init_client(struct i2c_client *client);
+static int lm77_detach_client(struct i2c_client *client);
+static u16 lm77_read_value(struct i2c_client *client, u8 reg);
+static int lm77_write_value(struct i2c_client *client, u8 reg, u16 value);
+
+static struct lm77_data *lm77_update_device(struct device *dev);
+
+
+/* This is the driver that will be inserted */
+static struct i2c_driver lm77_driver = {
+	.owner		= THIS_MODULE,
+	.name		= "lm77",
+	.flags		= I2C_DF_NOTIFY,
+	.attach_adapter = lm77_attach_adapter,
+	.detach_client	= lm77_detach_client,
+};
+
+static int lm77_id = 0;
+
+/* straight from the datasheet */
+#define LM77_TEMP_MIN (-55000)
+#define LM77_TEMP_MAX 125000
+
+/* In the temperature registers, the low 3 bits are not part of the
+   temperature values; they are the status bits. */
+static inline u16 LM77_TEMP_TO_REG(int temp)
+{
+	int ntemp = SENSORS_LIMIT(temp, LM77_TEMP_MIN, LM77_TEMP_MAX);
+	return (u16)((ntemp / 500) * 8);
+}
+
+static inline int LM77_TEMP_FROM_REG(u16 reg)
+{
+	return ((int)reg / 8) * 500;
+}
+
+/* sysfs stuff */
+
+/* read routines for temperature limits */
+#define show(value)	\
+static ssize_t show_##value(struct device *dev, char *buf)	\
+{								\
+	struct lm77_data *data = lm77_update_device(dev);	\
+	return sprintf(buf, "%d\n", data->value);		\
+}
+
+show(temp_input);
+show(temp_crit);
+show(temp_min);
+show(temp_max);
+show(alarms);
+
+/* read routines for hysteresis values */
+static ssize_t show_temp_crit_hyst(struct device *dev, char *buf)
+{
+	struct lm77_data *data = lm77_update_device(dev);
+	return sprintf(buf, "%d\n", data->temp_crit - data->temp_hyst);
+}
+static ssize_t show_temp_min_hyst(struct device *dev, char *buf)
+{
+	struct lm77_data *data = lm77_update_device(dev);
+	return sprintf(buf, "%d\n", data->temp_min + data->temp_hyst);
+}
+static ssize_t show_temp_max_hyst(struct device *dev, char *buf)
+{
+	struct lm77_data *data = lm77_update_device(dev);
+	return sprintf(buf, "%d\n", data->temp_max - data->temp_hyst);
+}
+
+/* write routines */
+#define set(value, reg)	\
+static ssize_t set_##value(struct device *dev, const char *buf, size_t count)	\
+{										\
+	struct i2c_client *client = to_i2c_client(dev);				\
+	struct lm77_data *data = i2c_get_clientdata(client);			\
+	data->value = simple_strtoul(buf, NULL, 10);				\
+	lm77_write_value(client, reg, LM77_TEMP_TO_REG(data->value));		\
+	return count;								\
+}
+
+set(temp_min, LM77_REG_TEMP_MIN);
+set(temp_max, LM77_REG_TEMP_MAX);
+
+/* hysteresis is stored as a relative value on the chip, so it has to be
+   converted first */
+static ssize_t set_temp_crit_hyst(struct device *dev, const char *buf, size_t count)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct lm77_data *data = i2c_get_clientdata(client);
+	data->temp_hyst = data->temp_crit - simple_strtoul(buf, NULL, 10);
+	lm77_write_value(client, LM77_REG_TEMP_HYST,
+			 LM77_TEMP_TO_REG(data->temp_hyst));
+	return count;
+}
+
+/* preserve hysteresis when setting T_crit */
+static ssize_t set_temp_crit(struct device *dev, const char *buf, size_t count)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct lm77_data *data = i2c_get_clientdata(client);
+	int oldcrithyst = data->temp_crit - data->temp_hyst;
+	data->temp_crit = simple_strtoul(buf, NULL, 10);
+	data->temp_hyst = data->temp_crit - oldcrithyst;
+	lm77_write_value(client, LM77_REG_TEMP_CRIT,
+			 LM77_TEMP_TO_REG(data->temp_crit));
+	lm77_write_value(client, LM77_REG_TEMP_HYST,
+			 LM77_TEMP_TO_REG(data->temp_hyst));
+	return count;
+}
+
+static DEVICE_ATTR(temp1_input, S_IRUGO,
+		   show_temp_input, NULL);
+static DEVICE_ATTR(temp1_crit, S_IWUSR | S_IRUGO,
+		   show_temp_crit, set_temp_crit);
+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 DEVICE_ATTR(temp1_crit_hyst, S_IWUSR | S_IRUGO,
+		   show_temp_crit_hyst, set_temp_crit_hyst);
+static DEVICE_ATTR(temp1_min_hyst, S_IRUGO,
+		   show_temp_min_hyst, NULL);
+static DEVICE_ATTR(temp1_max_hyst, S_IRUGO,
+		   show_temp_max_hyst, NULL);
+
+static DEVICE_ATTR(alarms, S_IRUGO,
+		   show_alarms, NULL);
+
+static int lm77_attach_adapter(struct i2c_adapter *adapter)
+{
+	if (!(adapter->class & I2C_CLASS_HWMON))
+		return 0;
+	return i2c_detect(adapter, &addr_data, lm77_detect);
+}
+
+/* This function is called by i2c_detect */
+static int lm77_detect(struct i2c_adapter *adapter, int address, int kind)
+{
+	struct i2c_client *new_client;
+	struct lm77_data *data;
+	int err = 0;
+	const char *name = "";
+
+	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA |
+				     I2C_FUNC_SMBUS_WORD_DATA))
+		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 lm77_{read,write}_value. */
+	if (!(data = kmalloc(sizeof(struct lm77_data), GFP_KERNEL))) {
+		err = -ENOMEM;
+		goto exit;
+	}
+	memset(data, 0, sizeof(struct lm77_data));
+
+	new_client = &data->client;
+	i2c_set_clientdata(new_client, data);
+	new_client->addr = address;
+	new_client->adapter = adapter;
+	new_client->driver = &lm77_driver;
+	new_client->flags = 0;
+
+	/* Here comes the remaining detection.  Since the LM77 has no
+	   register dedicated to identification, we have to rely on the
+	   following tricks:
+
+	   1. the high 4 bits represent the sign and thus they should
+	      always be the same
+	   2. the high 3 bits are unused in the configuration register
+	   3. addresses 0x06 and 0x07 return the last read value
+	   4. registers cycling over 8-address boundaries
+
+	   Word-sized registers are high-byte first. */
+	if (kind < 0) {
+		int i, cur, conf, hyst, crit, min, max;
+
+		/* addresses cycling */
+		cur = i2c_smbus_read_word_data(new_client, 0);
+		conf = i2c_smbus_read_byte_data(new_client, 1);
+		hyst = i2c_smbus_read_word_data(new_client, 2);
+		crit = i2c_smbus_read_word_data(new_client, 3);
+		min = i2c_smbus_read_word_data(new_client, 4);
+		max = i2c_smbus_read_word_data(new_client, 5);
+		for (i = 8; i <= 0xff; i += 8)
+			if (i2c_smbus_read_byte_data(new_client, i + 1) != conf
+			    || i2c_smbus_read_word_data(new_client, i + 2) != hyst
+			    || i2c_smbus_read_word_data(new_client, i + 3) != crit
+			    || i2c_smbus_read_word_data(new_client, i + 4) != min
+			    || i2c_smbus_read_word_data(new_client, i + 5) != max)
+				goto exit_free;
+
+		/* sign bits */
+		if (((cur & 0x00f0) != 0xf0 && (cur & 0x00f0) != 0x0)
+		    || ((hyst & 0x00f0) != 0xf0 && (hyst & 0x00f0) != 0x0)
+		    || ((crit & 0x00f0) != 0xf0 && (crit & 0x00f0) != 0x0)
+		    || ((min & 0x00f0) != 0xf0 && (min & 0x00f0) != 0x0)
+		    || ((max & 0x00f0) != 0xf0 && (max & 0x00f0) != 0x0))
+			goto exit_free;
+
+		/* unused bits */
+		if (conf & 0xe0)
+			goto exit_free;
+
+		/* 0x06 and 0x07 return the last read value */
+		cur = i2c_smbus_read_word_data(new_client, 0);
+		if (i2c_smbus_read_word_data(new_client, 6) != cur
+		    || i2c_smbus_read_word_data(new_client, 7) != cur)
+			goto exit_free;
+		hyst = i2c_smbus_read_word_data(new_client, 2);
+		if (i2c_smbus_read_word_data(new_client, 6) != hyst
+		    || i2c_smbus_read_word_data(new_client, 7) != hyst)
+			goto exit_free;
+		min = i2c_smbus_read_word_data(new_client, 4);
+		if (i2c_smbus_read_word_data(new_client, 6) != min
+		    || i2c_smbus_read_word_data(new_client, 7) != min)
+			goto exit_free;
+
+	}
+
+	/* Determine the chip type - only one kind supported! */
+	if (kind <= 0)
+		kind = lm77;
+
+	if (kind == lm77) {
+		name = "lm77";
+	}
+
+	/* Fill in the remaining client fields and put it into the global list */
+	strlcpy(new_client->name, name, I2C_NAME_SIZE);
+
+	new_client->id = lm77_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 LM77 chip */
+	lm77_init_client(new_client);
+
+	/* Register sysfs hooks */
+	device_create_file(&new_client->dev, &dev_attr_temp1_input);
+	device_create_file(&new_client->dev, &dev_attr_temp1_crit);
+	device_create_file(&new_client->dev, &dev_attr_temp1_min);
+	device_create_file(&new_client->dev, &dev_attr_temp1_max);
+	device_create_file(&new_client->dev, &dev_attr_temp1_crit_hyst);
+	device_create_file(&new_client->dev, &dev_attr_temp1_min_hyst);
+	device_create_file(&new_client->dev, &dev_attr_temp1_max_hyst);
+	device_create_file(&new_client->dev, &dev_attr_alarms);
+	return 0;
+
+exit_free:
+	kfree(data);
+exit:
+	return err;
+}
+
+static int lm77_detach_client(struct i2c_client *client)
+{
+	i2c_detach_client(client);
+	kfree(i2c_get_clientdata(client));
+	return 0;
+}
+
+/* All registers are word-sized, except for the configuration register.
+   The LM77 uses the high-byte first convention. */
+static u16 lm77_read_value(struct i2c_client *client, u8 reg)
+{
+	if (reg == LM77_REG_CONF)
+		return i2c_smbus_read_byte_data(client, reg);
+	else
+		return swab16(i2c_smbus_read_word_data(client, reg));
+}
+
+static int lm77_write_value(struct i2c_client *client, u8 reg, u16 value)
+{
+	if (reg == LM77_REG_CONF)
+		return i2c_smbus_write_byte_data(client, reg, value);
+	else
+		return i2c_smbus_write_word_data(client, reg, swab16(value));
+}
+
+static void lm77_init_client(struct i2c_client *client)
+{
+	/* Initialize the LM77 chip - turn off shutdown mode */
+	int conf = lm77_read_value(client, LM77_REG_CONF);
+	if (conf & 1)
+		lm77_write_value(client, LM77_REG_CONF, conf & 0xfe);
+}
+
+static struct lm77_data *lm77_update_device(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct lm77_data *data = i2c_get_clientdata(client);
+
+	down(&data->update_lock);
+
+	if ((jiffies - data->last_updated > HZ + HZ / 2) ||
+	    (jiffies < data->last_updated) || !data->valid) {
+		dev_dbg(&client->dev, "Starting lm77 update\n");
+		data->temp_input =
+			LM77_TEMP_FROM_REG(lm77_read_value(client,
+							   LM77_REG_TEMP));
+		data->temp_hyst =
+			LM77_TEMP_FROM_REG(lm77_read_value(client,
+							   LM77_REG_TEMP_HYST));
+		data->temp_crit =
+			LM77_TEMP_FROM_REG(lm77_read_value(client,
+							   LM77_REG_TEMP_CRIT));
+		data->temp_min =
+			LM77_TEMP_FROM_REG(lm77_read_value(client,
+							   LM77_REG_TEMP_MIN));
+		data->temp_max =
+			LM77_TEMP_FROM_REG(lm77_read_value(client,
+							   LM77_REG_TEMP_MAX));
+		data->alarms =
+			lm77_read_value(client, LM77_REG_TEMP) & 0x0007;
+		data->last_updated = jiffies;
+		data->valid = 1;
+	}
+
+	up(&data->update_lock);
+
+	return data;
+}
+
+static int __init sensors_lm77_init(void)
+{
+	return i2c_add_driver(&lm77_driver);
+}
+
+static void __exit sensors_lm77_exit(void)
+{
+	i2c_del_driver(&lm77_driver);
+}
+
+MODULE_AUTHOR("Andras BALI <drewie@freemail.hu>");
+MODULE_DESCRIPTION("LM77 driver");
+MODULE_LICENSE("GPL");
+
+module_init(sensors_lm77_init);
+module_exit(sensors_lm77_exit);