hwmon: (ads7828) driver cleanup

As there is no reliable way to identify the chip, it is preferable to
remove the detect callback, to avoid misdetection.

Module parameters are not worth it here, so let's get rid of them and
add an ads7828_platform_data structure instead.

Clean the code by removing unused macros, fixing coding style issues,
avoiding function prototypes and using convenient macros such as
module_i2c_driver().

Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Documentation/hwmon/ads7828

@@ -4,22 +4,33 @@ Kernel driver ads7828
 Supported chips:
   * Texas Instruments/Burr-Brown ADS7828
     Prefix: 'ads7828'
-    Addresses scanned: I2C 0x48, 0x49, 0x4a, 0x4b
-    Datasheet: Publicly available at the Texas Instruments website :
+    Datasheet: Publicly available at the Texas Instruments website:
                http://focus.ti.com/lit/ds/symlink/ads7828.pdf
 
 Authors:
         Steve Hardy <shardy@redhat.com>
+        Vivien Didelot <vivien.didelot@savoirfairelinux.com>
 
-Module Parameters
------------------
+Platform data
+-------------
 
-* se_input: bool (default Y)
-  Single ended operation - set to N for differential mode
-* int_vref: bool (default Y)
-  Operate with the internal 2.5V reference - set to N for external reference
-* vref_mv: int (default 2500)
-  If using an external reference, set this to the reference voltage in mV
+The ads7828 driver accepts an optional ads7828_platform_data structure (defined
+in include/linux/platform_data/ads7828.h). The structure fields are:
+
+* diff_input: (bool) Differential operation
+  set to true for differential mode, false for default single ended mode.
+
+* ext_vref: (bool) External reference
+  set to true if it operates with an external reference, false for default
+  internal reference.
+
+* vref_mv: (unsigned int) Voltage reference
+  if using an external reference, set this to the reference voltage in mV,
+  otherwise it will default to the internal value (2500mV). This value will be
+  bounded with limits accepted by the chip, described in the datasheet.
+
+ If no structure is provided, the configuration defaults to single ended
+ operation and internal voltage reference (2.5V).
 
 Description
 -----------
@@ -34,3 +45,7 @@ where 4 differential pairs can be measured.
 The chip also has the facility to use an external voltage reference.  This
 may be required if your hardware supplies the ADS7828 from a 5V supply, see
 the datasheet for more details.
+
+There is no reliable way to identify this chip, so the driver will not scan
+some addresses to try to auto-detect it. That means that you will have to
+statically declare the device in the platform support code.

drivers/hwmon/ads7828.c

@@ -6,7 +6,7 @@
  *
  * Written by Steve Hardy <shardy@redhat.com>
  *
- * Datasheet available at: http://focus.ti.com/lit/ds/symlink/ads7828.pdf
+ * For further information, see the Documentation/hwmon/ads7828 file.
  *
  * 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
@@ -23,63 +23,44 @@
  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  */
 
-#include <linux/module.h>
-#include <linux/init.h>
-#include <linux/slab.h>
-#include <linux/jiffies.h>
-#include <linux/i2c.h>
+#include <linux/err.h>
 #include <linux/hwmon.h>
 #include <linux/hwmon-sysfs.h>
-#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/jiffies.h>
+#include <linux/module.h>
 #include <linux/mutex.h>
+#include <linux/platform_data/ads7828.h>
+#include <linux/slab.h>
 
 /* The ADS7828 registers */
-#define ADS7828_NCH 8 /* 8 channels of 12-bit A-D supported */
-#define ADS7828_CMD_SD_SE 0x80 /* Single ended inputs */
-#define ADS7828_CMD_SD_DIFF 0x00 /* Differential inputs */
-#define ADS7828_CMD_PD0 0x0 /* Power Down between A-D conversions */
-#define ADS7828_CMD_PD1 0x04 /* Internal ref OFF && A-D ON */
-#define ADS7828_CMD_PD2 0x08 /* Internal ref ON && A-D OFF */
-#define ADS7828_CMD_PD3 0x0C /* Internal ref ON && A-D ON */
-#define ADS7828_INT_VREF_MV 2500 /* Internal vref is 2.5V, 2500mV */
-
-/* Addresses to scan */
-static const unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b,
-	I2C_CLIENT_END };
-
-/* Module parameters */
-static bool se_input = 1; /* Default is SE, 0 == diff */
-static bool int_vref = 1; /* Default is internal ref ON */
-static int vref_mv = ADS7828_INT_VREF_MV; /* set if vref != 2.5V */
-module_param(se_input, bool, S_IRUGO);
-module_param(int_vref, bool, S_IRUGO);
-module_param(vref_mv, int, S_IRUGO);
-
-/* Global Variables */
-static u8 ads7828_cmd_byte; /* cmd byte without channel bits */
-static unsigned int ads7828_lsb_resol; /* resolution of the ADC sample lsb */
-
-/* Each client has this additional data */
+#define ADS7828_NCH		8	/* 8 channels supported */
+#define ADS7828_CMD_SD_SE	0x80	/* Single ended inputs */
+#define ADS7828_CMD_PD1		0x04	/* Internal vref OFF && A/D ON */
+#define ADS7828_CMD_PD3		0x0C	/* Internal vref ON && A/D ON */
+#define ADS7828_INT_VREF_MV	2500	/* Internal vref is 2.5V, 2500mV */
+#define ADS7828_EXT_VREF_MV_MIN	50	/* External vref min value 0.05V */
+#define ADS7828_EXT_VREF_MV_MAX	5250	/* External vref max value 5.25V */
+
+/* Client specific data */
 struct ads7828_data {
 	struct device *hwmon_dev;
-	struct mutex update_lock; /* mutex protect updates */
-	char valid; /* !=0 if following fields are valid */
-	unsigned long last_updated; /* In jiffies */
-	u16 adc_input[ADS7828_NCH]; /* ADS7828_NCH 12-bit samples */
+	struct mutex update_lock;	/* Mutex protecting updates */
+	unsigned long last_updated;	/* Last updated time (in jiffies) */
+	u16 adc_input[ADS7828_NCH];	/* ADS7828_NCH samples */
+	bool valid;			/* Validity flag */
+	bool diff_input;		/* Differential input */
+	bool ext_vref;			/* External voltage reference */
+	unsigned int vref_mv;		/* voltage reference value */
+	u8 cmd_byte;			/* Command byte without channel bits */
+	unsigned int lsb_resol;		/* Resolution of the ADC sample LSB */
 };
 
-/* Function declaration - necessary due to function dependencies */
-static int ads7828_detect(struct i2c_client *client,
-			  struct i2c_board_info *info);
-static int ads7828_probe(struct i2c_client *client,
-			 const struct i2c_device_id *id);
-
-static inline u8 channel_cmd_byte(int ch)
+/* Command byte C2,C1,C0 - see datasheet */
+static inline u8 ads7828_cmd_byte(u8 cmd, int ch)
 {
-	/* cmd byte C2,C1,C0 - see datasheet */
-	u8 cmd = (((ch>>1) | (ch&0x01)<<2)<<4);
-	cmd |= ads7828_cmd_byte;
-	return cmd;
+	return cmd | (((ch >> 1) | (ch & 0x01) << 2) << 4);
 }
 
 /* Update data for the device (all 8 channels) */
@@ -96,12 +77,12 @@ static struct ads7828_data *ads7828_update_device(struct device *dev)
 		dev_dbg(&client->dev, "Starting ads7828 update\n");
 
 		for (ch = 0; ch < ADS7828_NCH; ch++) {
-			u8 cmd = channel_cmd_byte(ch);
+			u8 cmd = ads7828_cmd_byte(data->cmd_byte, ch);
 			data->adc_input[ch] =
 				i2c_smbus_read_word_swapped(client, cmd);
 		}
 		data->last_updated = jiffies;
-		data->valid = 1;
+		data->valid = true;
 	}
 
 	mutex_unlock(&data->update_lock);
@@ -110,28 +91,25 @@ static struct ads7828_data *ads7828_update_device(struct device *dev)
 }
 
 /* sysfs callback function */
-static ssize_t show_in(struct device *dev, struct device_attribute *da,
-	char *buf)
+static ssize_t ads7828_show_in(struct device *dev, struct device_attribute *da,
+			       char *buf)
 {
 	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
 	struct ads7828_data *data = ads7828_update_device(dev);
-	/* Print value (in mV as specified in sysfs-interface documentation) */
-	return sprintf(buf, "%d\n", (data->adc_input[attr->index] *
-		ads7828_lsb_resol)/1000);
-}
+	unsigned int value = DIV_ROUND_CLOSEST(data->adc_input[attr->index] *
+					       data->lsb_resol, 1000);
 
-#define in_reg(offset)\
-static SENSOR_DEVICE_ATTR(in##offset##_input, S_IRUGO, show_in,\
-	NULL, offset)
+	return sprintf(buf, "%d\n", value);
+}
 
-in_reg(0);
-in_reg(1);
-in_reg(2);
-in_reg(3);
-in_reg(4);
-in_reg(5);
-in_reg(6);
-in_reg(7);
+static SENSOR_DEVICE_ATTR(in0_input, S_IRUGO, ads7828_show_in, NULL, 0);
+static SENSOR_DEVICE_ATTR(in1_input, S_IRUGO, ads7828_show_in, NULL, 1);
+static SENSOR_DEVICE_ATTR(in2_input, S_IRUGO, ads7828_show_in, NULL, 2);
+static SENSOR_DEVICE_ATTR(in3_input, S_IRUGO, ads7828_show_in, NULL, 3);
+static SENSOR_DEVICE_ATTR(in4_input, S_IRUGO, ads7828_show_in, NULL, 4);
+static SENSOR_DEVICE_ATTR(in5_input, S_IRUGO, ads7828_show_in, NULL, 5);
+static SENSOR_DEVICE_ATTR(in6_input, S_IRUGO, ads7828_show_in, NULL, 6);
+static SENSOR_DEVICE_ATTR(in7_input, S_IRUGO, ads7828_show_in, NULL, 7);
 
 static struct attribute *ads7828_attributes[] = {
 	&sensor_dev_attr_in0_input.dev_attr.attr,
@@ -152,60 +130,9 @@ static const struct attribute_group ads7828_group = {
 static int ads7828_remove(struct i2c_client *client)
 {
 	struct ads7828_data *data = i2c_get_clientdata(client);
+
 	hwmon_device_unregister(data->hwmon_dev);
 	sysfs_remove_group(&client->dev.kobj, &ads7828_group);
-	return 0;
-}
-
-static const struct i2c_device_id ads7828_id[] = {
-	{ "ads7828", 0 },
-	{ }
-};
-MODULE_DEVICE_TABLE(i2c, ads7828_id);
-
-/* This is the driver that will be inserted */
-static struct i2c_driver ads7828_driver = {
-	.class = I2C_CLASS_HWMON,
-	.driver = {
-		.name = "ads7828",
-	},
-	.probe = ads7828_probe,
-	.remove = ads7828_remove,
-	.id_table = ads7828_id,
-	.detect = ads7828_detect,
-	.address_list = normal_i2c,
-};
-
-/* Return 0 if detection is successful, -ENODEV otherwise */
-static int ads7828_detect(struct i2c_client *client,
-			  struct i2c_board_info *info)
-{
-	struct i2c_adapter *adapter = client->adapter;
-	int ch;
-
-	/* Check we have a valid client */
-	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_WORD_DATA))
-		return -ENODEV;
-
-	/*
-	 * Now, we do the remaining detection. There is no identification
-	 * dedicated register so attempt to sanity check using knowledge of
-	 * the chip
-	 * - Read from the 8 channel addresses
-	 * - Check the top 4 bits of each result are not set (12 data bits)
-	 */
-	for (ch = 0; ch < ADS7828_NCH; ch++) {
-		u16 in_data;
-		u8 cmd = channel_cmd_byte(ch);
-		in_data = i2c_smbus_read_word_swapped(client, cmd);
-		if (in_data & 0xF000) {
-			pr_debug("%s : Doesn't look like an ads7828 device\n",
-				 __func__);
-			return -ENODEV;
-		}
-	}
-
-	strlcpy(info->type, "ads7828", I2C_NAME_SIZE);
 
 	return 0;
 }
@@ -213,6 +140,7 @@ static int ads7828_detect(struct i2c_client *client,
 static int ads7828_probe(struct i2c_client *client,
 			 const struct i2c_device_id *id)
 {
+	struct ads7828_platform_data *pdata = client->dev.platform_data;
 	struct ads7828_data *data;
 	int err;
 
@@ -221,10 +149,30 @@ static int ads7828_probe(struct i2c_client *client,
 	if (!data)
 		return -ENOMEM;
 
+	if (pdata) {
+		data->diff_input = pdata->diff_input;
+		data->ext_vref = pdata->ext_vref;
+		if (data->ext_vref)
+			data->vref_mv = pdata->vref_mv;
+	}
+
+	/* Bound Vref with min/max values if it was provided */
+	if (data->vref_mv)
+		data->vref_mv = SENSORS_LIMIT(data->vref_mv,
+					      ADS7828_EXT_VREF_MV_MIN,
+					      ADS7828_EXT_VREF_MV_MAX);
+	else
+		data->vref_mv = ADS7828_INT_VREF_MV;
+
+	data->lsb_resol = DIV_ROUND_CLOSEST(data->vref_mv * 1000, 4096);
+
+	data->cmd_byte = data->ext_vref ? ADS7828_CMD_PD1 : ADS7828_CMD_PD3;
+	if (!data->diff_input)
+		data->cmd_byte |= ADS7828_CMD_SD_SE;
+
 	i2c_set_clientdata(client, data);
 	mutex_init(&data->update_lock);
 
-	/* Register sysfs hooks */
 	err = sysfs_create_group(&client->dev.kobj, &ads7828_group);
 	if (err)
 		return err;
@@ -232,38 +180,34 @@ static int ads7828_probe(struct i2c_client *client,
 	data->hwmon_dev = hwmon_device_register(&client->dev);
 	if (IS_ERR(data->hwmon_dev)) {
 		err = PTR_ERR(data->hwmon_dev);
-		goto exit_remove;
+		goto error;
 	}
 
 	return 0;
 
-exit_remove:
+error:
 	sysfs_remove_group(&client->dev.kobj, &ads7828_group);
 	return err;
 }
 
-static int __init sensors_ads7828_init(void)
-{
-	/* Initialize the command byte according to module parameters */
-	ads7828_cmd_byte = se_input ?
-		ADS7828_CMD_SD_SE : ADS7828_CMD_SD_DIFF;
-	ads7828_cmd_byte |= int_vref ?
-		ADS7828_CMD_PD3 : ADS7828_CMD_PD1;
+static const struct i2c_device_id ads7828_device_ids[] = {
+	{ "ads7828", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, ads7828_device_ids);
 
-	/* Calculate the LSB resolution */
-	ads7828_lsb_resol = (vref_mv*1000)/4096;
+static struct i2c_driver ads7828_driver = {
+	.driver = {
+		.name = "ads7828",
+	},
 
-	return i2c_add_driver(&ads7828_driver);
-}
+	.id_table = ads7828_device_ids,
+	.probe = ads7828_probe,
+	.remove = ads7828_remove,
+};
 
-static void __exit sensors_ads7828_exit(void)
-{
-	i2c_del_driver(&ads7828_driver);
-}
+module_i2c_driver(ads7828_driver);
 
-MODULE_AUTHOR("Steve Hardy <shardy@redhat.com>");
-MODULE_DESCRIPTION("ADS7828 driver");
 MODULE_LICENSE("GPL");
-
-module_init(sensors_ads7828_init);
-module_exit(sensors_ads7828_exit);
+MODULE_AUTHOR("Steve Hardy <shardy@redhat.com>");
+MODULE_DESCRIPTION("Driver for TI ADS7828 A/D converter");

include/linux/platform_data/ads7828.h

@@ -0,0 +1,29 @@
+/*
+ * TI ADS7828 A/D Converter platform data definition
+ *
+ * Copyright (c) 2012 Savoir-faire Linux Inc.
+ *          Vivien Didelot <vivien.didelot@savoirfairelinux.com>
+ *
+ * For further information, see the Documentation/hwmon/ads7828 file.
+ *
+ * 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 _PDATA_ADS7828_H
+#define _PDATA_ADS7828_H
+
+/**
+ * struct ads7828_platform_data - optional ADS7828 connectivity info
+ * @diff_input:		Differential input mode.
+ * @ext_vref:		Use an external voltage reference.
+ * @vref_mv:		Voltage reference value, if external.
+ */
+struct ads7828_platform_data {
+	bool diff_input;
+	bool ext_vref;
+	unsigned int vref_mv;
+};
+
+#endif /* _PDATA_ADS7828_H */