[lm-sensors] [PATCH] hwmon: (ads7828) add support for ADS7830

* [lm-sensors] [PATCH] hwmon: (ads7828) add support for ADS7830
@ 2012-10-01 20:44 ` Vivien Didelot
  0 siblings, 0 replies; 8+ messages in thread
From: Vivien Didelot @ 2012-10-01 20:44 UTC (permalink / raw)
  To: lm-sensors
  Cc: Guillaume Roguez, Guenter Roeck, Jean Delvare, linux-kernel,
	Steve Hardy, Vivien Didelot

From: Guillaume Roguez <guillaume.roguez@savoirfairelinux.com>

The ADS7830 is almost the same chip, except that it does 8-bit sampling.
This patch extends the ads7828 driver to support this device.

Signed-off-by: Guillaume Roguez <guillaume.roguez@savoirfairelinux.com>

Also clean the driver a bit by removing unused macros, and moving
the driver declaration to avoid some function prototypes.

Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
---
 Documentation/hwmon/ads7828 |  12 +++-
 drivers/hwmon/Kconfig       |   7 ++-
 drivers/hwmon/ads7828.c     | 137 +++++++++++++++++++++++++-------------------
 3 files changed, 93 insertions(+), 63 deletions(-)

diff --git a/Documentation/hwmon/ads7828 b/Documentation/hwmon/ads7828
index 2bbebe6..4366a87 100644
--- a/Documentation/hwmon/ads7828
+++ b/Documentation/hwmon/ads7828
@@ -8,8 +8,15 @@ Supported chips:
     Datasheet: Publicly available at the Texas Instruments website :
                http://focus.ti.com/lit/ds/symlink/ads7828.pdf
 
+  * Texas Instruments ADS7830
+    Prefix: 'ads7830'
+    Addresses scanned: I2C 0x48, 0x49, 0x4a, 0x4b
+    Datasheet: Publicly available at the Texas Instruments website:
+               http://focus.ti.com/lit/ds/symlink/ads7830.pdf
+
 Authors:
         Steve Hardy <shardy@redhat.com>
+        Guillaume Roguez <guillaume.roguez@savoirfairelinux.com>
 
 Module Parameters
 -----------------
@@ -24,9 +31,10 @@ Module Parameters
 Description
 -----------
 
-This driver implements support for the Texas Instruments ADS7828.
+This driver implements support for the Texas Instruments ADS7828, and ADS7830.
 
-This device is a 12-bit 8-channel A-D converter.
+The ADS7828 device is a 12-bit 8-channel A/D converter, while the ADS7830 does
+8-bit sampling.
 
 It can operate in single ended mode (8 +ve inputs) or in differential mode,
 where 4 differential pairs can be measured.
diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index 83e3e9d..960c8c5 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -1060,11 +1060,12 @@ config SENSORS_ADS1015
 	  will be called ads1015.
 
 config SENSORS_ADS7828
-	tristate "Texas Instruments ADS7828"
+	tristate "Texas Instruments ADS7828 and compatibles"
 	depends on I2C
 	help
-	  If you say yes here you get support for Texas Instruments ADS7828
-	  12-bit 8-channel ADC device.
+	  If you say yes here you get support for Texas Instruments ADS7828 and
+	  ADS7830 8-channel A/D converters. ADS7828 resolution is 12-bit, while
+	  it is 8-bit on ADS7830.
 
 	  This driver can also be built as a module.  If so, the module
 	  will be called ads7828.
diff --git a/drivers/hwmon/ads7828.c b/drivers/hwmon/ads7828.c
index bf3fdf4..58f28ea 100644
--- a/drivers/hwmon/ads7828.c
+++ b/drivers/hwmon/ads7828.c
@@ -1,12 +1,12 @@
 /*
- * ads7828.c - lm_sensors driver for ads7828 12-bit 8-channel ADC
- * (C) 2007 EADS Astrium
+ * ads7828.c - driver for TI ADS7828 8-channel A/D converter and compatibles
  *
- * This driver is based on the lm75 and other lm_sensors/hwmon drivers
+ * Copyright (C) 2007 EADS Astrium
+ * Copyright (C) Steve Hardy <shardy@redhat.com>
+ * Copyright (C) 2012 Savoir-faire Linux Inc.
+ *	Guillaume Roguez <guillaume.roguez@savoirfairelinux.com>
  *
- * 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
@@ -34,14 +34,15 @@
 #include <linux/mutex.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 */
+#define ADS7828_NCH		8	/* 8 channels supported */
+#define ADS7828_CMD_SD_SE	0x80	/* Single ended inputs */
+#define ADS7828_CMD_SD_DIFF	0x00	/* Differential inputs */
+#define ADS7828_CMD_PD1		0x04	/* Internal ref OFF && A/D ON */
+#define ADS7828_CMD_PD3		0x0C	/* Internal ref ON && A/D ON */
+#define ADS7828_INT_VREF_MV	2500	/* Internal vref is 2.5V, 2500mV */
+
+/* List of supported devices */
+enum ads7828_chips { ads7828, ads7830 };
 
 /* Addresses to scan */
 static const unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b,
@@ -57,23 +58,27 @@ 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 */
+/**
+ * struct ads7828_data - client specific data
+ * @hwmon_dev:		The hwmon device.
+ * @update_lock:	Mutex protecting updates.
+ * @valid:		Validity flag.
+ * @last_updated:	Last updated time (in jiffies).
+ * @adc_input:		ADS7828_NCH samples.
+ * @lsb_resol:		Resolution of the A/D converter sample LSB.
+ * @read_channel:	Function used to read a channel.
+ */
 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;
+	char valid;
+	unsigned long last_updated;
+	u16 adc_input[ADS7828_NCH];
+	unsigned int lsb_resol;
+	s32 (*read_channel)(const struct i2c_client *client, u8 command);
 };
 
-/* 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)
 {
 	/* cmd byte C2,C1,C0 - see datasheet */
@@ -97,8 +102,7 @@ static struct ads7828_data *ads7828_update_device(struct device *dev)
 
 		for (ch = 0; ch < ADS7828_NCH; ch++) {
 			u8 cmd = channel_cmd_byte(ch);
-			data->adc_input[ch] -				i2c_smbus_read_word_swapped(client, cmd);
+			data->adc_input[ch] = data->read_channel(client, cmd);
 		}
 		data->last_updated = jiffies;
 		data->valid = 1;
@@ -116,8 +120,8 @@ static ssize_t show_in(struct device *dev, struct device_attribute *da,
 	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);
+	return sprintf(buf, "%d\n",
+		       (data->adc_input[attr->index] * data->lsb_resol) / 1000);
 }
 
 #define in_reg(offset)\
@@ -158,31 +162,13 @@ static int ads7828_remove(struct i2c_client *client)
 	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;
+	bool is_8bit = false;
 
 	/* Check we have a valid client */
 	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_WORD_DATA))
@@ -193,20 +179,30 @@ static int ads7828_detect(struct i2c_client *client,
 	 * 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)
+	 * - Check the top 4 bits of each result:
+	 *   - They should not be set in case of 12-bit samples
+	 *   - The two bytes should be equal in case of 8-bit samples
 	 */
 	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;
+			if ((in_data >> 8) = (in_data & 0xFF)) {
+				/* Seems to be an ADS7830 (8-bit sample) */
+				is_8bit = true;
+			} else {
+				dev_dbg(&client->dev, "doesn't look like an "
+					"ADS7828 compatible device\n");
+				return -ENODEV;
+			}
 		}
 	}
 
-	strlcpy(info->type, "ads7828", I2C_NAME_SIZE);
+	if (is_8bit)
+		strlcpy(info->type, "ads7830", I2C_NAME_SIZE);
+	else
+		strlcpy(info->type, "ads7828", I2C_NAME_SIZE);
 
 	return 0;
 }
@@ -223,6 +219,15 @@ static int ads7828_probe(struct i2c_client *client,
 		goto exit;
 	}
 
+	/* ADS7828 uses 12-bit samples, while ADS7830 is 8-bit */
+	if (id->driver_data = ads7828) {
+		data->read_channel = i2c_smbus_read_word_swapped;
+		data->lsb_resol = (vref_mv * 1000) / 4096;
+	} else {
+		data->read_channel = i2c_smbus_read_byte_data;
+		data->lsb_resol = (vref_mv * 1000) / 256;
+	}
+
 	i2c_set_clientdata(client, data);
 	mutex_init(&data->update_lock);
 
@@ -247,6 +252,25 @@ exit:
 	return err;
 }
 
+static const struct i2c_device_id ads7828_ids[] = {
+	{ "ads7828", ads7828 },
+	{ "ads7830", ads7830 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, ads7828_ids);
+
+static struct i2c_driver ads7828_driver = {
+	.class = I2C_CLASS_HWMON,
+	.driver = {
+		.name = "ads7828",
+	},
+	.probe = ads7828_probe,
+	.remove = ads7828_remove,
+	.id_table = ads7828_ids,
+	.detect = ads7828_detect,
+	.address_list = normal_i2c,
+};
+
 static int __init sensors_ads7828_init(void)
 {
 	/* Initialize the command byte according to module parameters */
@@ -255,9 +279,6 @@ static int __init sensors_ads7828_init(void)
 	ads7828_cmd_byte |= int_vref ?
 		ADS7828_CMD_PD3 : ADS7828_CMD_PD1;
 
-	/* Calculate the LSB resolution */
-	ads7828_lsb_resol = (vref_mv*1000)/4096;
-
 	return i2c_add_driver(&ads7828_driver);
 }
 
@@ -267,7 +288,7 @@ static void __exit sensors_ads7828_exit(void)
 }
 
 MODULE_AUTHOR("Steve Hardy <shardy@redhat.com>");
-MODULE_DESCRIPTION("ADS7828 driver");
+MODULE_DESCRIPTION("Driver for TI ADS7828 A/D converter and compatibles");
 MODULE_LICENSE("GPL");
 
 module_init(sensors_ads7828_init);
-- 
1.7.11.4


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