[PATCH 1/1] : hwmon - new chip driver for TI ADS7828 A-D

[PATCH 1/1] : hwmon - new chip driver for TI ADS7828 A-D

[Steve Hardy]

Hi,

Here is a patch against 2.6.23.9 which adds support for the 
Burr-Brown/Texas-Instruments
ADS7828 12-bit 8-channel A-D converter.

The chip is used for voltage monitoring on the COTS processor card I am
currently working with.

The driver simply outputs the current input voltages (in mv as specified
in the lm-sensors sysfs interface documentation).  Any scaling required for
a specific board is handled by user-space.  Hopefully this makes the driver
generic enough to be generally useful.

The driver is basically a simple rehash of existing code - I used lm75 as
the starting point, with some inspiration from other existing drivers.

Please let me know if there are any problems with the patch.

Regards,
Steve


Developer's Certificate of Origin 1.1

By making a contribution to this project, I certify that:

(a) The contribution was created in whole or in part by me and I
    have the right to submit it under the open source license
    indicated in the file; or

(b) The contribution is based upon previous work that, to the best
    of my knowledge, is covered under an appropriate open source
    license and I have the right under that license to submit that
    work with modifications, whether created in whole or in part
    by me, under the same open source license (unless I am
    permitted to submit under a different license), as indicated
    in the file; or

(c) The contribution was provided directly to me by some other
    person who certified (a), (b) or (c) and I have not modified
    it.

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    are public and that a record of the contribution (including all
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    maintained indefinitely and may be redistributed consistent with
    this project or the open source license(s) involved.

Signed-off-by: Steve Hardy <steve@linuxrealtime.co.uk>

---

diff -uprN -X linux-2.6.23.9/Documentation/dontdiff 
linux-2.6.23.9/drivers/hwmon/Kconfig 
linux-2.6.23.9-ads7828/drivers/hwmon/Kconfig
--- linux-2.6.23.9/drivers/hwmon/Kconfig    2007-11-26 
17:51:43.000000000 +0000
+++ linux-2.6.23.9-ads7828/drivers/hwmon/Kconfig    2007-11-28 
10:02:02.000000000 +0000
@@ -530,6 +530,16 @@ config SENSORS_THMC50
       This driver can also be built as a module.  If so, the module
       will be called thmc50.
 
+config SENSORS_ADS7828
+    tristate "Texas Instruments ADS7828"
+    depends on I2C && EXPERIMENTAL
+    help
+      If you say yes here you get support for Texas Instruments ADS7828
+      12-bit 8-channel ADC device
+
+      This driver can also be built as a module.  If so, the module
+      will be called ads7828
+
 config SENSORS_VIA686A
     tristate "VIA686A"
     depends on PCI
diff -uprN -X linux-2.6.23.9/Documentation/dontdiff 
linux-2.6.23.9/drivers/hwmon/Makefile 
linux-2.6.23.9-ads7828/drivers/hwmon/Makefile
--- linux-2.6.23.9/drivers/hwmon/Makefile    2007-11-26 
17:51:43.000000000 +0000
+++ linux-2.6.23.9-ads7828/drivers/hwmon/Makefile    2007-11-28 
10:02:02.000000000 +0000
@@ -22,6 +22,7 @@ obj-$(CONFIG_SENSORS_ADM1026)    += adm1026
 obj-$(CONFIG_SENSORS_ADM1029)    += adm1029.o
 obj-$(CONFIG_SENSORS_ADM1031)    += adm1031.o
 obj-$(CONFIG_SENSORS_ADM9240)    += adm9240.o
+obj-$(CONFIG_SENSORS_ADS7828)    += ads7828.o
 obj-$(CONFIG_SENSORS_APPLESMC)    += applesmc.o
 obj-$(CONFIG_SENSORS_AMS)    += ams/
 obj-$(CONFIG_SENSORS_ATXP1)    += atxp1.o
diff -uprN -X linux-2.6.23.9/Documentation/dontdiff 
linux-2.6.23.9/drivers/hwmon/ads7828.c 
linux-2.6.23.9-ads7828/drivers/hwmon/ads7828.c
--- linux-2.6.23.9/drivers/hwmon/ads7828.c    1970-01-01 
01:00:00.000000000 +0100
+++ linux-2.6.23.9-ads7828/drivers/hwmon/ads7828.c    2007-11-28 
10:02:02.000000000 +0000
@@ -0,0 +1,304 @@
+/*
+    ads7828.c - lm_sensors driver for ads7828 12bit 8ch ADC
+    (C) 2007 EADS Astrium
+
+    This driver is based on the lm75 and other lm_sensors/hwmon drivers
+
+    Written by Steve Hardy <steve@linuxrealtime.co.uk>
+
+    Datasheet available at : http://focus.ti.com/lit/ds/symlink/ads7828.pdf
+
+    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/jiffies.h>
+#include <linux/i2c.h>
+#include <linux/hwmon.h>
+#include <linux/hwmon-sysfs.h>
+#include <linux/err.h>
+#include <linux/mutex.h>
+
+/* Addresses to scan */
+static unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b,
+    I2C_CLIENT_END };
+
+/* Insmod parameters */
+I2C_CLIENT_INSMOD_1(ads7828);
+
+/* The ADS7828 registers */
+#define ADS7828_NCH 8 /* 8 channels of 12bit 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 2500 /* Internal vref is 2.5v, 2500mV */
+
+/* module parameters */
+static int ads7828_se_input = 1; /* Default is SE, 0 == diff */
+static int ads7828_int_vref = 1; /* Default is internal ref ON */
+static int ads7828_vref = ADS7828_INT_VREF; /* set if vref != 2.5v */
+module_param(ads7828_se_input, bool, S_IRUGO);
+module_param(ads7828_int_vref, bool, S_IRUGO);
+module_param(ads7828_vref, int, S_IRUGO);
+
+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 {
+    struct i2c_client client;
+    struct class_device *class_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 12bit samples */
+};
+
+static int ads7828_attach_adapter(struct i2c_adapter *adapter);
+static int ads7828_detect(struct i2c_adapter *adapter, int address, int 
kind);
+static void ads7828_init_client(struct i2c_client *client);
+static int ads7828_detach_client(struct i2c_client *client);
+static struct ads7828_data *ads7828_update_device(struct device *dev);
+static u16 ads7828_read_value(struct i2c_client *client, u8 reg);
+
+/* This is the driver that will be inserted */
+static struct i2c_driver ads7828_driver = {
+    .driver = {
+        .name = "ads7828",
+    },
+    .id = I2C_DRIVERID_ADS7828,
+    .attach_adapter = ads7828_attach_adapter,
+    .detach_client = ads7828_detach_client,
+};
+
+static ssize_t 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 sysctl-interface 
documentation) */
+    return sprintf(buf, "%d\n", (data->adc_input[attr->index] *
+        ads7828_lsb_resol)/1000);
+}
+
+#define in_reg(offset)\
+static SENSOR_DEVICE_ATTR(in##offset##_input, S_IRUGO, show_in,\
+    NULL, offset);
+
+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 int ads7828_attach_adapter(struct i2c_adapter *adapter)
+{
+    if (!(adapter->class & I2C_CLASS_HWMON))
+        return 0;
+    return i2c_probe(adapter, &addr_data, ads7828_detect);
+}
+
+static struct attribute *ads7828_attributes[] = {
+    &sensor_dev_attr_in0_input.dev_attr.attr,
+    &sensor_dev_attr_in1_input.dev_attr.attr,
+    &sensor_dev_attr_in2_input.dev_attr.attr,
+    &sensor_dev_attr_in3_input.dev_attr.attr,
+    &sensor_dev_attr_in4_input.dev_attr.attr,
+    &sensor_dev_attr_in5_input.dev_attr.attr,
+    &sensor_dev_attr_in6_input.dev_attr.attr,
+    &sensor_dev_attr_in7_input.dev_attr.attr,
+    NULL
+};
+
+static const struct attribute_group ads7828_group = {
+    .attrs = ads7828_attributes,
+};
+
+/* This function is called by i2c_detect */
+static int ads7828_detect(struct i2c_adapter *adapter, int address, int 
kind)
+{
+    struct i2c_client *new_client;
+    struct ads7828_data *data;
+    int err = 0, ch = 0;
+    const char *name = "";
+    u8 cmd;
+    u16 in_data;
+
+    /* Check we have a valid client */
+    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 ads7828_read_value. */
+    data = kmalloc(sizeof(struct ads7828_data), GFP_KERNEL);
+    if (!data)
+        err = -ENOMEM;
+        goto exit;
+    }
+    memset(data, 0, sizeof(struct ads7828_data));
+
+    new_client = &data->client;
+    i2c_set_clientdata(new_client, data);
+    new_client->addr = address;
+    new_client->adapter = adapter;
+    new_client->driver = &ads7828_driver;
+    new_client->flags = 0;
+
+    /* Perform local initialisation */
+    ads7828_init_client(new_client);
+
+    /* 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)
+    */
+    if (kind < 0) {
+        for (ch = 0; ch < ADS7828_NCH; ch++) {
+            /* cmd byte C2,C1,C0 - see datasheet */
+            cmd = (((ch>>1) | (ch&0x01)<<2)<<4);
+            cmd |= ads7828_cmd_byte;
+            in_data = ads7828_read_value(new_client, cmd);
+            if (in_data & 0xF000) {
+                printk(KERN_DEBUG
+                "%s : Doesn't look like an ads7828 device\n",
+                __FUNCTION__);
+                goto exit_free;
+            }
+        }
+    }
+
+    /* Determine the chip type - only one kind supported! */
+    if (kind <= 0)
+        kind = ads7828;
+
+    if (kind == ads7828)
+        name = "ads7828";
+
+    /* Fill in the remaining client fields, put it into the global list */
+    strlcpy(new_client->name, name, I2C_NAME_SIZE);
+    data->valid = 0;
+    mutex_init(&data->update_lock);
+
+    /* Tell the I2C layer a new client has arrived */
+    err = i2c_attach_client(new_client);
+    if (err)
+        goto exit_free;
+
+    /* Register sysfs hooks */
+    err = sysfs_create_group(&new_client->dev.kobj, &ads7828_group);
+    if (err)
+        goto exit_detach;
+
+    data->class_dev = hwmon_device_register(&new_client->dev);
+    if (IS_ERR(data->class_dev)) {
+        err = PTR_ERR(data->class_dev);
+        goto exit_remove;
+    }
+
+    return 0;
+
+exit_remove:
+    sysfs_remove_group(&new_client->dev.kobj, &ads7828_group);
+exit_detach:
+    i2c_detach_client(new_client);
+exit_free:
+    kfree(data);
+exit:
+    return err;
+}
+
+static int ads7828_detach_client(struct i2c_client *client)
+{
+    struct ads7828_data *data = i2c_get_clientdata(client);
+    hwmon_device_unregister(data->class_dev);
+    sysfs_remove_group(&client->dev.kobj, &ads7828_group);
+    i2c_detach_client(client);
+    kfree(i2c_get_clientdata(client));
+    return 0;
+}
+
+/* The ADS7828 returns the 12bit sample in two bytes,
+    these are read as a word then byte-swapped */
+static u16 ads7828_read_value(struct i2c_client *client, u8 reg)
+{
+    u16 buffer = i2c_smbus_read_word_data(client, reg);
+    return ((buffer&0xFF)<<8) | ((buffer&0xFF00)>>8);
+}
+
+static void ads7828_init_client(struct i2c_client *client)
+{
+    /* Initialise the command byte according to module parameters */
+    ads7828_cmd_byte = ads7828_se_input ?
+        ADS7828_CMD_SD_SE : ADS7828_CMD_SD_DIFF;
+    ads7828_cmd_byte |= ads7828_int_vref ?
+        ADS7828_CMD_PD3 : ADS7828_CMD_PD1;
+
+    /* Calculate the LSB resolution */
+    ads7828_lsb_resol = (ads7828_vref*1000)/4096;
+}
+
+static struct ads7828_data *ads7828_update_device(struct device *dev)
+{
+    struct i2c_client *client = to_i2c_client(dev);
+    struct ads7828_data *data = i2c_get_clientdata(client);
+    unsigned int cmd, ch;
+
+    mutex_lock(&data->update_lock); /* LOCK */
+
+    if (time_after(jiffies, data->last_updated + HZ + HZ / 2)
+            || !data->valid) {
+        dev_dbg(&client->dev, "Starting ads7828 update\n");
+
+        for (ch = 0; ch < ADS7828_NCH; ch++) {
+            /* cmd byte C2,C1,C0 - see datasheet */
+            cmd = (((ch>>1) | (ch&0x01)<<2)<<4);
+            cmd |= ads7828_cmd_byte;
+            data->adc_input[ch] = ads7828_read_value(client, cmd);
+        }
+        data->last_updated = jiffies;
+        data->valid = 1;
+    }
+
+    mutex_unlock(&data->update_lock); /* UNLOCK */
+
+    return data;
+}
+
+static int __init sensors_ads7828_init(void)
+{
+    return i2c_add_driver(&ads7828_driver);
+}
+
+static void __exit sensors_ads7828_exit(void)
+{
+    i2c_del_driver(&ads7828_driver);
+}
+
+MODULE_AUTHOR("Steve Hardy <steve@linuxrealtime.co.uk");
+MODULE_DESCRIPTION("ADS7828 driver");
+MODULE_LICENSE("GPL");
+
+module_init(sensors_ads7828_init);
+module_exit(sensors_ads7828_exit);
diff -uprN -X linux-2.6.23.9/Documentation/dontdiff 
linux-2.6.23.9/include/linux/i2c-id.h 
linux-2.6.23.9-ads7828/include/linux/i2c-id.h
--- linux-2.6.23.9/include/linux/i2c-id.h    2007-11-26 
17:51:43.000000000 +0000
+++ linux-2.6.23.9-ads7828/include/linux/i2c-id.h    2007-11-28 
10:02:02.000000000 +0000
@@ -161,6 +161,7 @@
 #define I2C_DRIVERID_FSCHER 1046
 #define I2C_DRIVERID_W83L785TS 1047
 #define I2C_DRIVERID_OV7670 1048    /* Omnivision 7670 camera */
+#define I2C_DRIVERID_ADS7828 1049
 
 /*
  * ---- Adapter types ----------------------------------------------------

Re: [PATCH 1/1] : hwmon - new chip driver for TI ADS7828 A-D

[Andrew Morton]

On Mon, 03 Dec 2007 17:59:59 +0000 Steve Hardy <steve@linuxrealtime.co.uk> wrote:

> Hi,
> 
> Here is a patch against 2.6.23.9 which adds support for the 
> Burr-Brown/Texas-Instruments
> ADS7828 12-bit 8-channel A-D converter.
> 
> The chip is used for voltage monitoring on the COTS processor card I am
> currently working with.
> 
> The driver simply outputs the current input voltages (in mv as specified
> in the lm-sensors sysfs interface documentation).  Any scaling required for
> a specific board is handled by user-space.  Hopefully this makes the driver
> generic enough to be generally useful.
> 
> The driver is basically a simple rehash of existing code - I used lm75 as
> the starting point, with some inspiration from other existing drivers.
> 
> ...
>
> diff -uprN -X linux-2.6.23.9/Documentation/dontdiff 
> linux-2.6.23.9/drivers/hwmon/Kconfig 
> linux-2.6.23.9-ads7828/drivers/hwmon/Kconfig
> --- linux-2.6.23.9/drivers/hwmon/Kconfig    2007-11-26 
> 17:51:43.000000000 +0000
> +++ linux-2.6.23.9-ads7828/drivers/hwmon/Kconfig    2007-11-28 

Your email client is wordwrapping the text and it replaces tabs with
spaces.  It will need a resend, please.

> @@ -530,6 +530,16 @@ config SENSORS_THMC50
>        This driver can also be built as a module.  If so, the module
>        will be called thmc50.
>  
> +config SENSORS_ADS7828
> +    tristate "Texas Instruments ADS7828"
> +    depends on I2C && EXPERIMENTAL

I wouldn't bother with EXPERIMENTAL personally.  It seems a farily
pointless thing.

> linux-2.6.23.9-ads7828/drivers/hwmon/ads7828.c

Please prepare and test patches against the latest Linus tree, from git or
from ftp://ftp.kernel.org/pub/linux/kernel/v2.6/snapshots

Usually it's OK to develop a new driver against the latest stable release,
but we regularly change interfaces and if we did, this driver won't even
compile.

> +static int ads7828_attach_adapter(struct i2c_adapter *adapter);
> +static int ads7828_detect(struct i2c_adapter *adapter, int address, int 
> kind);
> +static void ads7828_init_client(struct i2c_client *client);
> +static int ads7828_detach_client(struct i2c_client *client);
> +static struct ads7828_data *ads7828_update_device(struct device *dev);
> +static u16 ads7828_read_value(struct i2c_client *client, u8 reg);

I do dislike all these forward declarations, but they're all needed here
give the order of the functions.  Maybe from my Pascal-on-pdp11 days..

> +/* This is the driver that will be inserted */
> +static struct i2c_driver ads7828_driver = {
> +    .driver = {
> +        .name = "ads7828",
> +    },
> +    .id = I2C_DRIVERID_ADS7828,
> +    .attach_adapter = ads7828_attach_adapter,
> +    .detach_client = ads7828_detach_client,
> +};
> +
> +static ssize_t 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 sysctl-interface 
> documentation) */
> +    return sprintf(buf, "%d\n", (data->adc_input[attr->index] *
> +        ads7828_lsb_resol)/1000);
> +}
> +
> +#define in_reg(offset)\
> +static SENSOR_DEVICE_ATTR(in##offset##_input, S_IRUGO, show_in,\
> +    NULL, offset);
> +
> +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 int ads7828_attach_adapter(struct i2c_adapter *adapter)
> +{
> +    if (!(adapter->class & I2C_CLASS_HWMON))
> +        return 0;

Can this happen?

> +    return i2c_probe(adapter, &addr_data, ads7828_detect);
> +}
> +
> +static struct attribute *ads7828_attributes[] = {
> +    &sensor_dev_attr_in0_input.dev_attr.attr,
> +    &sensor_dev_attr_in1_input.dev_attr.attr,
> +    &sensor_dev_attr_in2_input.dev_attr.attr,
> +    &sensor_dev_attr_in3_input.dev_attr.attr,
> +    &sensor_dev_attr_in4_input.dev_attr.attr,
> +    &sensor_dev_attr_in5_input.dev_attr.attr,
> +    &sensor_dev_attr_in6_input.dev_attr.attr,
> +    &sensor_dev_attr_in7_input.dev_attr.attr,
> +    NULL
> +};
> +
> +static const struct attribute_group ads7828_group = {
> +    .attrs = ads7828_attributes,
> +};
> +
> +/* This function is called by i2c_detect */
> +static int ads7828_detect(struct i2c_adapter *adapter, int address, int 
> kind)
> +{
> +    struct i2c_client *new_client;
> +    struct ads7828_data *data;
> +    int err = 0, ch = 0;
> +    const char *name = "";
> +    u8 cmd;
> +    u16 in_data;
> +
> +    /* Check we have a valid client */
> +    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 ads7828_read_value. */
> +    data = kmalloc(sizeof(struct ads7828_data), GFP_KERNEL);
> +    if (!data)
> +        err = -ENOMEM;
> +        goto exit;
> +    }
> +    memset(data, 0, sizeof(struct ads7828_data));

Use kzalloc() above, remove the memset.

> +    new_client = &data->client;
> +    i2c_set_clientdata(new_client, data);
> +    new_client->addr = address;
> +    new_client->adapter = adapter;
> +    new_client->driver = &ads7828_driver;
> +    new_client->flags = 0;
> +
> +    /* Perform local initialisation */
> +    ads7828_init_client(new_client);
> +
> +    /* 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)
> +    */
> +    if (kind < 0) {
> +        for (ch = 0; ch < ADS7828_NCH; ch++) {
> +            /* cmd byte C2,C1,C0 - see datasheet */
> +            cmd = (((ch>>1) | (ch&0x01)<<2)<<4);
> +            cmd |= ads7828_cmd_byte;
> +            in_data = ads7828_read_value(new_client, cmd);
> +            if (in_data & 0xF000) {
> +                printk(KERN_DEBUG
> +                "%s : Doesn't look like an ads7828 device\n",
> +                __FUNCTION__);
> +                goto exit_free;
> +            }
> +        }
> +    }
> +
> +    /* Determine the chip type - only one kind supported! */
> +    if (kind <= 0)
> +        kind = ads7828;
> +
> +    if (kind == ads7828)
> +        name = "ads7828";
> +
> +    /* Fill in the remaining client fields, put it into the global list */
> +    strlcpy(new_client->name, name, I2C_NAME_SIZE);
> +    data->valid = 0;
> +    mutex_init(&data->update_lock);
> +
> +    /* Tell the I2C layer a new client has arrived */
> +    err = i2c_attach_client(new_client);
> +    if (err)
> +        goto exit_free;
> +
> +    /* Register sysfs hooks */
> +    err = sysfs_create_group(&new_client->dev.kobj, &ads7828_group);
> +    if (err)
> +        goto exit_detach;
> +
> +    data->class_dev = hwmon_device_register(&new_client->dev);
> +    if (IS_ERR(data->class_dev)) {
> +        err = PTR_ERR(data->class_dev);
> +        goto exit_remove;
> +    }
> +
> +    return 0;
> +
> +exit_remove:
> +    sysfs_remove_group(&new_client->dev.kobj, &ads7828_group);
> +exit_detach:
> +    i2c_detach_client(new_client);
> +exit_free:
> +    kfree(data);
> +exit:
> +    return err;
> +}
>
> ...
>
> +static struct ads7828_data *ads7828_update_device(struct device *dev)
> +{
> +    struct i2c_client *client = to_i2c_client(dev);
> +    struct ads7828_data *data = i2c_get_clientdata(client);
> +    unsigned int cmd, ch;
> +
> +    mutex_lock(&data->update_lock); /* LOCK */

I don't think that comment adds a lot of value ;)

> +    if (time_after(jiffies, data->last_updated + HZ + HZ / 2)
> +            || !data->valid) {
> +        dev_dbg(&client->dev, "Starting ads7828 update\n");
> +
> +        for (ch = 0; ch < ADS7828_NCH; ch++) {
> +            /* cmd byte C2,C1,C0 - see datasheet */
> +            cmd = (((ch>>1) | (ch&0x01)<<2)<<4);
> +            cmd |= ads7828_cmd_byte;
> +            data->adc_input[ch] = ads7828_read_value(client, cmd);
> +        }
> +        data->last_updated = jiffies;
> +        data->valid = 1;
> +    }
> +
> +    mutex_unlock(&data->update_lock); /* UNLOCK */

But that one's great!

> +    return data;
> +}
> +
> +static int __init sensors_ads7828_init(void)
> +{
> +    return i2c_add_driver(&ads7828_driver);
> +}
> +
> +static void __exit sensors_ads7828_exit(void)
> +{
> +    i2c_del_driver(&ads7828_driver);
> +}
> +
> +MODULE_AUTHOR("Steve Hardy <steve@linuxrealtime.co.uk");
> +MODULE_DESCRIPTION("ADS7828 driver");
> +MODULE_LICENSE("GPL");
> +
> +module_init(sensors_ads7828_init);
> +module_exit(sensors_ads7828_exit);
> diff -uprN -X linux-2.6.23.9/Documentation/dontdiff 
> linux-2.6.23.9/include/linux/i2c-id.h 
> linux-2.6.23.9-ads7828/include/linux/i2c-id.h
> --- linux-2.6.23.9/include/linux/i2c-id.h    2007-11-26 
> 17:51:43.000000000 +0000
> +++ linux-2.6.23.9-ads7828/include/linux/i2c-id.h    2007-11-28 
> 10:02:02.000000000 +0000
> @@ -161,6 +161,7 @@
>  #define I2C_DRIVERID_FSCHER 1046
>  #define I2C_DRIVERID_W83L785TS 1047
>  #define I2C_DRIVERID_OV7670 1048    /* Omnivision 7670 camera */
> +#define I2C_DRIVERID_ADS7828 1049

It all looks reasonable.  I'd have applied it if it weren't for the
mailer-mangling.

Re: [PATCH 1/1] : hwmon - new chip driver for TI ADS7828 A-D

[Steve Hardy]

Andrew,

Thanks your your comments, I'm currently preparing/testing a revised patch based on your suggestions, which I will post later this week.

A couple of comments inline.

Steve

> I wouldn't bother with EXPERIMENTAL personally.  It seems a farily
> pointless thing.
> 

OK, I copied one of the other hwmon drivers, many of which are marked experimental.

>> +static int ads7828_attach_adapter(struct i2c_adapter *adapter);
>> +static int ads7828_detect(struct i2c_adapter *adapter, int address, int 
>> kind);
>> +static void ads7828_init_client(struct i2c_client *client);
>> +static int ads7828_detach_client(struct i2c_client *client);
>> +static struct ads7828_data *ads7828_update_device(struct device *dev);
>> +static u16 ads7828_read_value(struct i2c_client *client, u8 reg);
> 
> I do dislike all these forward declarations, but they're all needed here
> give the order of the functions.  Maybe from my Pascal-on-pdp11 days..
> 

OK, this is due to re-using the driver structure/style of other hwmon drivers, will try to improve.

>> +static int ads7828_attach_adapter(struct i2c_adapter *adapter)
>> +{
>> +    if (!(adapter->class & I2C_CLASS_HWMON))
>> +        return 0;
> 
> Can this happen?

Hmmm, this code exists in pretty much all of the other hwmon drivers, so I will leave it in.

I think it relates to I2C vs ISA connected devices, to avoid detecting something with the correct ID on the wrong bus?

Re: [PATCH 1/1] : hwmon - new chip driver for TI ADS7828 A-D

[Jean Delvare]

Hi Steve, Andrew,

Thanks for the review Andrew. I have some more comments, I'll reply to
the original post.

On Tue, 18 Dec 2007 20:56:44 +0000, Steve Hardy wrote:
> >> +static int ads7828_attach_adapter(struct i2c_adapter *adapter)
> >> +{
> >> +    if (!(adapter->class & I2C_CLASS_HWMON))
> >> +        return 0;
> > 
> > Can this happen?
> 
> Hmmm, this code exists in pretty much all of the other hwmon
> drivers, so I will leave it in.
> 
> I think it relates to I2C vs ISA connected devices, to avoid
> detecting something with the correct ID on the wrong bus?

Not at all ;) It relates to I2C buses being used in various devices
such as TV adapters, which do not have hardware monitoring chips and do
not like being randomly probed for I2C devices as most hardware
monitoring drivers do when you load them.

-- 
Jean Delvare

Re: [PATCH 1/1] : hwmon - new chip driver for TI ADS7828 A-D

[Jean Delvare]

Hi Steve,

On Mon, 03 Dec 2007 17:59:59 +0000, Steve Hardy wrote:
> Here is a patch against 2.6.23.9 which adds support for the 
> Burr-Brown/Texas-Instruments
> ADS7828 12-bit 8-channel A-D converter.
> 
> The chip is used for voltage monitoring on the COTS processor card I am
> currently working with.
> 
> The driver simply outputs the current input voltages (in mv as specified
> in the lm-sensors sysfs interface documentation).  Any scaling required for
> a specific board is handled by user-space.  Hopefully this makes the driver
> generic enough to be generally useful.
> 
> The driver is basically a simple rehash of existing code - I used lm75 as
> the starting point, with some inspiration from other existing drivers.
> 
> Please let me know if there are any problems with the patch.

Preliminary note: if the chip is on an embedded platform where you can
declare the devices as platform data, writing a new-style I2C driver
would probably be easier. This would save you the detection step (which
I am not sure is very reliable) and device configuration would also be
much easier.

I have some random comments on top of what Andrew already wrote:

> diff -uprN -X linux-2.6.23.9/Documentation/dontdiff 
> linux-2.6.23.9/drivers/hwmon/Kconfig 
> linux-2.6.23.9-ads7828/drivers/hwmon/Kconfig
> --- linux-2.6.23.9/drivers/hwmon/Kconfig    2007-11-26 
> 17:51:43.000000000 +0000
> +++ linux-2.6.23.9-ads7828/drivers/hwmon/Kconfig    2007-11-28 
> 10:02:02.000000000 +0000
> @@ -530,6 +530,16 @@ config SENSORS_THMC50
>        This driver can also be built as a module.  If so, the module
>        will be called thmc50.
>  
> +config SENSORS_ADS7828
> +    tristate "Texas Instruments ADS7828"
> +    depends on I2C && EXPERIMENTAL
> +    help
> +      If you say yes here you get support for Texas Instruments ADS7828
> +      12-bit 8-channel ADC device

Missing final dot.

> +
> +      This driver can also be built as a module.  If so, the module
> +      will be called ads7828

Ditto.

> +
>  config SENSORS_VIA686A
>      tristate "VIA686A"
>      depends on PCI

> diff -uprN -X linux-2.6.23.9/Documentation/dontdiff 
> linux-2.6.23.9/drivers/hwmon/ads7828.c 
> linux-2.6.23.9-ads7828/drivers/hwmon/ads7828.c
> --- linux-2.6.23.9/drivers/hwmon/ads7828.c    1970-01-01 
> 01:00:00.000000000 +0100
> +++ linux-2.6.23.9-ads7828/drivers/hwmon/ads7828.c    2007-11-28 
> 10:02:02.000000000 +0000
> @@ -0,0 +1,304 @@
> +/*
> +    ads7828.c - lm_sensors driver for ads7828 12bit 8ch ADC
> +    (C) 2007 EADS Astrium
> +
> +    This driver is based on the lm75 and other lm_sensors/hwmon drivers
> +
> +    Written by Steve Hardy <steve@linuxrealtime.co.uk>
> +
> +    Datasheet available at : http://focus.ti.com/lit/ds/symlink/ads7828.pdf
> +
> +    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/jiffies.h>
> +#include <linux/i2c.h>
> +#include <linux/hwmon.h>
> +#include <linux/hwmon-sysfs.h>
> +#include <linux/err.h>
> +#include <linux/mutex.h>
> +
> +/* Addresses to scan */
> +static unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b,
> +    I2C_CLIENT_END };
> +
> +/* Insmod parameters */
> +I2C_CLIENT_INSMOD_1(ads7828);
> +
> +/* The ADS7828 registers */
> +#define ADS7828_NCH 8 /* 8 channels of 12bit 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 2500 /* Internal vref is 2.5v, 2500mV */
> +
> +/* module parameters */
> +static int ads7828_se_input = 1; /* Default is SE, 0 == diff */
> +static int ads7828_int_vref = 1; /* Default is internal ref ON */
> +static int ads7828_vref = ADS7828_INT_VREF; /* set if vref != 2.5v */
> +module_param(ads7828_se_input, bool, S_IRUGO);
> +module_param(ads7828_int_vref, bool, S_IRUGO);
> +module_param(ads7828_vref, int, S_IRUGO);
> +
> +static u8 ads7828_cmd_byte; /* cmd byte without channel bits */
> +static unsigned int ads7828_lsb_resol; /* resolution of the ADC sample lsb */

What's the unit of ads7828_lsb_resol?

All these parameters deserve some documentation in
Documentation/hwmon/ads7828. See the other files in this directory for
the expected format. Note that it is usual to not include the driver
name in the parameter names.

> +
> +/* Each client has this additional data */
> +struct ads7828_data {
> +    struct i2c_client client;
> +    struct class_device *class_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 12bit samples */
> +};
> +
> +static int ads7828_attach_adapter(struct i2c_adapter *adapter);
> +static int ads7828_detect(struct i2c_adapter *adapter, int address, int 
> kind);
> +static void ads7828_init_client(struct i2c_client *client);
> +static int ads7828_detach_client(struct i2c_client *client);
> +static struct ads7828_data *ads7828_update_device(struct device *dev);
> +static u16 ads7828_read_value(struct i2c_client *client, u8 reg);
> +
> +/* This is the driver that will be inserted */
> +static struct i2c_driver ads7828_driver = {
> +    .driver = {
> +        .name = "ads7828",
> +    },
> +    .id = I2C_DRIVERID_ADS7828,

What do you need this ID for? The I2C driver ID is optional and in most
cases hardware monitoring-drivers don't need any, so you can just omit it.

> +    .attach_adapter = ads7828_attach_adapter,
> +    .detach_client = ads7828_detach_client,
> +};
> +
> +static ssize_t 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 sysctl-interface documentation) */

sysfs, not sysctl.

> +    return sprintf(buf, "%d\n", (data->adc_input[attr->index] *
> +        ads7828_lsb_resol)/1000);
> +}
> +
> +#define in_reg(offset)\
> +static SENSOR_DEVICE_ATTR(in##offset##_input, S_IRUGO, show_in,\
> +    NULL, offset);
> +
> +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 int ads7828_attach_adapter(struct i2c_adapter *adapter)
> +{
> +    if (!(adapter->class & I2C_CLASS_HWMON))
> +        return 0;
> +    return i2c_probe(adapter, &addr_data, ads7828_detect);
> +}
> +
> +static struct attribute *ads7828_attributes[] = {
> +    &sensor_dev_attr_in0_input.dev_attr.attr,
> +    &sensor_dev_attr_in1_input.dev_attr.attr,
> +    &sensor_dev_attr_in2_input.dev_attr.attr,
> +    &sensor_dev_attr_in3_input.dev_attr.attr,
> +    &sensor_dev_attr_in4_input.dev_attr.attr,
> +    &sensor_dev_attr_in5_input.dev_attr.attr,
> +    &sensor_dev_attr_in6_input.dev_attr.attr,
> +    &sensor_dev_attr_in7_input.dev_attr.attr,
> +    NULL
> +};
> +
> +static const struct attribute_group ads7828_group = {
> +    .attrs = ads7828_attributes,
> +};
> +
> +/* This function is called by i2c_detect */
> +static int ads7828_detect(struct i2c_adapter *adapter, int address, int 
> kind)
> +{
> +    struct i2c_client *new_client;

Please rename this to just "client".

> +    struct ads7828_data *data;
> +    int err = 0, ch = 0;

ch doesn't need to be initialized here. (In fact it doesn't even need
to be declared here - same for cmd and in_data below.)

> +    const char *name = "";
> +    u8 cmd;
> +    u16 in_data;
> +
> +    /* Check we have a valid client */
> +    if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA |
> +                         I2C_FUNC_SMBUS_WORD_DATA))

You're not using byte-size transactions, and you're never writing to
the device, so I2C_FUNC_SMBUS_READ_WORD_DATA is enough.

> +        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 ads7828_read_value. */
> +    data = kmalloc(sizeof(struct ads7828_data), GFP_KERNEL);
> +    if (!data)
> +        err = -ENOMEM;
> +        goto exit;
> +    }
> +    memset(data, 0, sizeof(struct ads7828_data));
> +
> +    new_client = &data->client;
> +    i2c_set_clientdata(new_client, data);
> +    new_client->addr = address;
> +    new_client->adapter = adapter;
> +    new_client->driver = &ads7828_driver;
> +    new_client->flags = 0;

This is redundant with the above memset (or kzalloc).

> +
> +    /* Perform local initialisation */
> +    ads7828_init_client(new_client);
> +
> +    /* 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)
> +    */
> +    if (kind < 0) {
> +        for (ch = 0; ch < ADS7828_NCH; ch++) {
> +            /* cmd byte C2,C1,C0 - see datasheet */
> +            cmd = (((ch>>1) | (ch&0x01)<<2)<<4);

You're using this formula several times in the driver, it would
probably be worth having a macro or even better, an inline function for
it.

> +            cmd |= ads7828_cmd_byte;
> +            in_data = ads7828_read_value(new_client, cmd);
> +            if (in_data & 0xF000) {
> +                printk(KERN_DEBUG
> +                "%s : Doesn't look like an ads7828 device\n",
> +                __FUNCTION__);

Please use dev_dbg(&adapter->dev, ...) instead, that way the user knows
what I2C bus was being probed. It might also be a good idea to include
the chip address in the log message. The function name OTOH doesn't
seem particularly useful to me.

> +                goto exit_free;
> +            }
> +        }
> +    }
> +
> +    /* Determine the chip type - only one kind supported! */
> +    if (kind <= 0)
> +        kind = ads7828;
> +
> +    if (kind == ads7828)
> +        name = "ads7828";
> +
> +    /* Fill in the remaining client fields, put it into the global list */
> +    strlcpy(new_client->name, name, I2C_NAME_SIZE);
> +    data->valid = 0;

Redundant.

> +    mutex_init(&data->update_lock);
> +
> +    /* Tell the I2C layer a new client has arrived */
> +    err = i2c_attach_client(new_client);
> +    if (err)
> +        goto exit_free;
> +
> +    /* Register sysfs hooks */
> +    err = sysfs_create_group(&new_client->dev.kobj, &ads7828_group);
> +    if (err)
> +        goto exit_detach;
> +
> +    data->class_dev = hwmon_device_register(&new_client->dev);
> +    if (IS_ERR(data->class_dev)) {
> +        err = PTR_ERR(data->class_dev);
> +        goto exit_remove;
> +    }
> +
> +    return 0;
> +
> +exit_remove:
> +    sysfs_remove_group(&new_client->dev.kobj, &ads7828_group);
> +exit_detach:
> +    i2c_detach_client(new_client);
> +exit_free:
> +    kfree(data);
> +exit:
> +    return err;
> +}
> +
> +static int ads7828_detach_client(struct i2c_client *client)
> +{
> +    struct ads7828_data *data = i2c_get_clientdata(client);
> +    hwmon_device_unregister(data->class_dev);
> +    sysfs_remove_group(&client->dev.kobj, &ads7828_group);
> +    i2c_detach_client(client);
> +    kfree(i2c_get_clientdata(client));
> +    return 0;
> +}
> +
> +/* The ADS7828 returns the 12bit sample in two bytes,
> +    these are read as a word then byte-swapped */
> +static u16 ads7828_read_value(struct i2c_client *client, u8 reg)
> +{
> +    u16 buffer = i2c_smbus_read_word_data(client, reg);
> +    return ((buffer&0xFF)<<8) | ((buffer&0xFF00)>>8);

Please use swab16(), as the lm75 driver and many others do.

> +}
> +
> +static void ads7828_init_client(struct i2c_client *client)
> +{
> +    /* Initialise the command byte according to module parameters */
> +    ads7828_cmd_byte = ads7828_se_input ?
> +        ADS7828_CMD_SD_SE : ADS7828_CMD_SD_DIFF;
> +    ads7828_cmd_byte |= ads7828_int_vref ?
> +        ADS7828_CMD_PD3 : ADS7828_CMD_PD1;
> +
> +    /* Calculate the LSB resolution */
> +    ads7828_lsb_resol = (ads7828_vref*1000)/4096;

It doesn't make sense to initialize these values as part of the device
initialization, given that these are global variables that are shared
by all devices. Either make these per-device values, or initialize them
on driver load (in sensors_ads7828_init.)

> +}
> +
> +static struct ads7828_data *ads7828_update_device(struct device *dev)
> +{
> +    struct i2c_client *client = to_i2c_client(dev);
> +    struct ads7828_data *data = i2c_get_clientdata(client);
> +    unsigned int cmd, ch;
> +
> +    mutex_lock(&data->update_lock); /* LOCK */
> +
> +    if (time_after(jiffies, data->last_updated + HZ + HZ / 2)
> +            || !data->valid) {
> +        dev_dbg(&client->dev, "Starting ads7828 update\n");
> +
> +        for (ch = 0; ch < ADS7828_NCH; ch++) {
> +            /* cmd byte C2,C1,C0 - see datasheet */
> +            cmd = (((ch>>1) | (ch&0x01)<<2)<<4);
> +            cmd |= ads7828_cmd_byte;
> +            data->adc_input[ch] = ads7828_read_value(client, cmd);
> +        }
> +        data->last_updated = jiffies;
> +        data->valid = 1;
> +    }
> +
> +    mutex_unlock(&data->update_lock); /* UNLOCK */
> +
> +    return data;
> +}
> +
> +static int __init sensors_ads7828_init(void)
> +{
> +    return i2c_add_driver(&ads7828_driver);
> +}
> +
> +static void __exit sensors_ads7828_exit(void)
> +{
> +    i2c_del_driver(&ads7828_driver);
> +}
> +
> +MODULE_AUTHOR("Steve Hardy <steve@linuxrealtime.co.uk");

Missing ">".

> +MODULE_DESCRIPTION("ADS7828 driver");
> +MODULE_LICENSE("GPL");
> +
> +module_init(sensors_ads7828_init);
> +module_exit(sensors_ads7828_exit);


-- 
Jean Delvare

Re: [PATCH 1/1] : hwmon - new chip driver for TI ADS7828 A-D

[Steve Hardy]

Andrew/Jean,

Sorry for the delay - christmas & getting mutt working delayed my
revised patch.  Here is an updated patch against 2.6.24-rc6, which
hopefully addresses all comments made so far.

Jean - you mentioned declaring the devices as platform data & writing
a new-style I2C driver - are there any examples of this approach I can
refer to?  I simply copied what is/was currently in-tree for this
driver, which seems to work well with the hardware I'm working with (a
COTS CPCI carrier)

Since I've dropped Thunderbird I hope the patch mangling will be
fixed.

Any problem, please let me know.

Regards,
Steve

Signed-Off by Steve Hardy <steve@linuxrealtime.co.uk>

---


diff -uprN -X linux-2.6.24-rc6/Documentation/dontdiff linux-2.6.24-rc6/Documentation/hwmon/ads7828 linux-2.6.24-rc6-ads7828/Documentation/hwmon/ads7828
--- linux-2.6.24-rc6/Documentation/hwmon/ads7828	1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.24-rc6-ads7828/Documentation/hwmon/ads7828	2008-01-02 16:30:39.000000000 +0000
@@ -0,0 +1,38 @@
+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 :
+               http://focus.ti.com/lit/ds/symlink/ads7828.pdf
+
+Authors:
+        Steve Hardy <steve@linuxrealtime.co.uk>
+
+Module Parameters
+-----------------
+
+* 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
+
+Description
+-----------
+
+This driver implements support for the Texas Instruments ADS7828.
+
+This device is a 12bit 8ch A-D converter.
+
+It can operate in single ended mode (8 +ve inputs) or in differential mode,
+when 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.
+
+
diff -uprN -X linux-2.6.24-rc6/Documentation/dontdiff linux-2.6.24-rc6/drivers/hwmon/Kconfig linux-2.6.24-rc6-ads7828/drivers/hwmon/Kconfig
--- linux-2.6.24-rc6/drivers/hwmon/Kconfig	2008-01-02 16:37:43.000000000 +0000
+++ linux-2.6.24-rc6-ads7828/drivers/hwmon/Kconfig	2008-01-02 16:49:42.000000000 +0000
@@ -588,6 +588,16 @@ config SENSORS_SMSC47B397
 	  This driver can also be built as a module.  If so, the module
 	  will be called smsc47b397.
 
+config SENSORS_ADS7828
+	tristate "Texas Instruments ADS7828"
+	depends on I2C
+	help
+	If you say yes here you get support for Texas Instruments ADS7828
+	12-bit 8-channel ADC device.
+
+	This driver can also be built as a module.  If so, the module
+	will be called ads7828.
+
 config SENSORS_THMC50
 	tristate "Texas Instruments THMC50 / Analog Devices ADM1022"
 	depends on I2C && EXPERIMENTAL
diff -uprN -X linux-2.6.24-rc6/Documentation/dontdiff linux-2.6.24-rc6/drivers/hwmon/Makefile linux-2.6.24-rc6-ads7828/drivers/hwmon/Makefile
--- linux-2.6.24-rc6/drivers/hwmon/Makefile	2008-01-02 16:37:43.000000000 +0000
+++ linux-2.6.24-rc6-ads7828/drivers/hwmon/Makefile	2008-01-02 16:35:27.000000000 +0000
@@ -22,6 +22,7 @@ obj-$(CONFIG_SENSORS_ADM1026)	+= adm1026
 obj-$(CONFIG_SENSORS_ADM1029)	+= adm1029.o
 obj-$(CONFIG_SENSORS_ADM1031)	+= adm1031.o
 obj-$(CONFIG_SENSORS_ADM9240)	+= adm9240.o
+obj-$(CONFIG_SENSORS_ADS7828)	+= ads7828.o
 obj-$(CONFIG_SENSORS_ADT7470)	+= adt7470.o
 obj-$(CONFIG_SENSORS_APPLESMC)	+= applesmc.o
 obj-$(CONFIG_SENSORS_AMS)	+= ams/
diff -uprN -X linux-2.6.24-rc6/Documentation/dontdiff linux-2.6.24-rc6/drivers/hwmon/ads7828.c linux-2.6.24-rc6-ads7828/drivers/hwmon/ads7828.c
--- linux-2.6.24-rc6/drivers/hwmon/ads7828.c	1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.24-rc6-ads7828/drivers/hwmon/ads7828.c	2008-01-02 16:35:27.000000000 +0000
@@ -0,0 +1,296 @@
+/*
+	ads7828.c - lm_sensors driver for ads7828 12bit 8ch ADC
+	(C) 2007 EADS Astrium
+
+	This driver is based on the lm75 and other lm_sensors/hwmon drivers
+
+	Written by Steve Hardy <steve@linuxrealtime.co.uk>
+
+	Datasheet available at : http://focus.ti.com/lit/ds/symlink/ads7828.pdf
+
+	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/jiffies.h>
+#include <linux/i2c.h>
+#include <linux/hwmon.h>
+#include <linux/hwmon-sysfs.h>
+#include <linux/err.h>
+#include <linux/mutex.h>
+
+/* The ADS7828 registers */
+#define ADS7828_NCH 8 /* 8 channels of 12bit 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 unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b,
+	I2C_CLIENT_END };
+
+/* Insmod parameters */
+I2C_CLIENT_INSMOD_1(ads7828);
+
+/* Other module parameters */
+static int se_input = 1; /* Default is SE, 0 == diff */
+static int 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 */
+struct ads7828_data {
+	struct i2c_client client;
+	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 12bit samples */
+};
+
+/* Function declaration - neccesary due to function dependencies */
+static int ads7828_detect(struct i2c_adapter *adapter, int address, int kind);
+
+/* The ADS7828 returns the 12bit sample in two bytes,
+	these are read as a word then byte-swapped */
+static u16 ads7828_read_value(struct i2c_client *client, u8 reg)
+{
+	return swab16(i2c_smbus_read_word_data(client, reg));
+}
+
+static inline u8 channel_cmd_byte(int ch)
+{
+	/* cmd byte C2,C1,C0 - see datasheet */
+	u8 cmd = (((ch>>1) | (ch&0x01)<<2)<<4);
+	cmd |= ads7828_cmd_byte;
+	return cmd;
+}
+
+/* Update data for the device (all 8 channels) */
+static struct ads7828_data *ads7828_update_device(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct ads7828_data *data = i2c_get_clientdata(client);
+
+	mutex_lock(&data->update_lock);
+
+	if (time_after(jiffies, data->last_updated + HZ + HZ / 2)
+			|| !data->valid) {
+		unsigned int ch;
+		dev_dbg(&client->dev, "Starting ads7828 update\n");
+
+		for (ch = 0; ch < ADS7828_NCH; ch++) {
+			u8 cmd = channel_cmd_byte(ch);
+			data->adc_input[ch] = ads7828_read_value(client, cmd);
+		}
+		data->last_updated = jiffies;
+		data->valid = 1;
+	}
+
+	mutex_unlock(&data->update_lock);
+
+	return data;
+}
+
+/* sysfs callback function */
+static ssize_t 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);
+}
+
+#define in_reg(offset)\
+static SENSOR_DEVICE_ATTR(in##offset##_input, S_IRUGO, show_in,\
+	NULL, offset);
+
+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 struct attribute *ads7828_attributes[] = {
+	&sensor_dev_attr_in0_input.dev_attr.attr,
+	&sensor_dev_attr_in1_input.dev_attr.attr,
+	&sensor_dev_attr_in2_input.dev_attr.attr,
+	&sensor_dev_attr_in3_input.dev_attr.attr,
+	&sensor_dev_attr_in4_input.dev_attr.attr,
+	&sensor_dev_attr_in5_input.dev_attr.attr,
+	&sensor_dev_attr_in6_input.dev_attr.attr,
+	&sensor_dev_attr_in7_input.dev_attr.attr,
+	NULL
+};
+
+static const struct attribute_group ads7828_group = {
+	.attrs = ads7828_attributes,
+};
+
+static int ads7828_attach_adapter(struct i2c_adapter *adapter)
+{
+	if (!(adapter->class & I2C_CLASS_HWMON))
+		return 0;
+	return i2c_probe(adapter, &addr_data, ads7828_detect);
+}
+
+static int ads7828_detach_client(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);
+	i2c_detach_client(client);
+	kfree(i2c_get_clientdata(client));
+	return 0;
+}
+
+/* This is the driver that will be inserted */
+static struct i2c_driver ads7828_driver = {
+	.driver = {
+		.name = "ads7828",
+	},
+	.attach_adapter = ads7828_attach_adapter,
+	.detach_client = ads7828_detach_client,
+};
+
+/* This function is called by i2c_detect */
+static int ads7828_detect(struct i2c_adapter *adapter, int address, int kind)
+{
+	struct i2c_client *client;
+	struct ads7828_data *data;
+	int err=0;
+	const char *name = "";
+
+	/* Check we have a valid client */
+	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_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 ads7828_read_value. */
+	data = kzalloc(sizeof(struct ads7828_data), GFP_KERNEL);
+	if (!data) {
+		err = -ENOMEM;
+		goto exit;
+	}
+
+	client = &data->client;
+	i2c_set_clientdata(client, data);
+	client->addr = address;
+	client->adapter = adapter;
+	client->driver = &ads7828_driver;
+
+	/* 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)
+	*/
+	if (kind < 0) {
+		int ch;
+		for (ch = 0; ch < ADS7828_NCH; ch++) {
+			u16 in_data;
+			u8 cmd = channel_cmd_byte(ch);
+			in_data = ads7828_read_value(client, cmd);
+			if (in_data & 0xF000) {
+				printk(KERN_DEBUG 
+				"%s : Doesn't look like an ads7828 device\n",
+				__FUNCTION__);
+				goto exit_free;
+			}
+		}
+	}
+
+	/* Determine the chip type - only one kind supported! */
+	if (kind <= 0)
+		kind = ads7828;
+
+	if (kind == ads7828)
+		name = "ads7828";
+
+	/* Fill in the remaining client fields, put it into the global list */
+	strlcpy(client->name, name, I2C_NAME_SIZE);
+
+	mutex_init(&data->update_lock);
+
+	/* Tell the I2C layer a new client has arrived */
+	err = i2c_attach_client(client);
+	if (err)
+		goto exit_free;
+
+	/* Register sysfs hooks */
+	err = sysfs_create_group(&client->dev.kobj, &ads7828_group);
+	if (err)
+		goto exit_detach;
+
+	data->hwmon_dev = hwmon_device_register(&client->dev);
+	if (IS_ERR(data->hwmon_dev)) {
+		err = PTR_ERR(data->hwmon_dev);
+		goto exit_remove;
+	}
+
+	return 0;
+
+exit_remove:
+	sysfs_remove_group(&client->dev.kobj, &ads7828_group);
+exit_detach:
+	i2c_detach_client(client);
+exit_free:
+	kfree(data);
+exit:
+	return err;
+}
+
+static int __init sensors_ads7828_init(void)
+{
+	/* Initialise 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;
+
+	/* Calculate the LSB resolution */
+	ads7828_lsb_resol = (vref_mv*1000)/4096;
+
+	return i2c_add_driver(&ads7828_driver);
+}
+
+static void __exit sensors_ads7828_exit(void)
+{
+	i2c_del_driver(&ads7828_driver);
+}
+
+MODULE_AUTHOR("Steve Hardy <steve@linuxrealtime.co.uk>");
+MODULE_DESCRIPTION("ADS7828 driver");
+MODULE_LICENSE("GPL");
+
+module_init(sensors_ads7828_init);
+module_exit(sensors_ads7828_exit);

Re: [PATCH 1/1] : hwmon - new chip driver for TI ADS7828 A-D

[Andrew Morton]

On Fri, 4 Jan 2008 07:34:39 +0000
Steve Hardy <steve@linuxrealtime.co.uk> wrote:

> Andrew/Jean,
> 
> Sorry for the delay - christmas & getting mutt working delayed my
> revised patch.  Here is an updated patch against 2.6.24-rc6, which
> hopefully addresses all comments made so far.
> 
> Jean - you mentioned declaring the devices as platform data & writing
> a new-style I2C driver - are there any examples of this approach I can
> refer to?  I simply copied what is/was currently in-tree for this
> driver, which seems to work well with the hardware I'm working with (a
> COTS CPCI carrier)
> 
> Since I've dropped Thunderbird I hope the patch mangling will be
> fixed.
> 
> Any problem, please let me know.
>

The above doesn't constitute a usable changelog.  I guess we don't really
need anything in this patch but please do remember that the changelog text
should be included in each new rev of a patch.

> 
> Signed-Off by Steve Hardy <steve@linuxrealtime.co.uk>

"Signed-off-by:", please.

 Documentation/hwmon/ads7828 |   38 ++++
 drivers/hwmon/Kconfig       |   10 +
 drivers/hwmon/Makefile      |    1 
 drivers/hwmon/ads7828.c     |  296 ++++++++++++++++++++++++++++++++++
 4 files changed, 345 insertions(+)

I assumed that this is to be merged via Mark's git-hwmon tree.

Re: [PATCH 1/1] : hwmon - new chip driver for TI ADS7828 A-D

[Jean Delvare]

Hi Steve,

On Fri, 4 Jan 2008 07:34:39 +0000, Steve Hardy wrote:
> Jean - you mentioned declaring the devices as platform data & writing
> a new-style I2C driver - are there any examples of this approach I can
> refer to?  I simply copied what is/was currently in-tree for this
> driver, which seems to work well with the hardware I'm working with (a
> COTS CPCI carrier)

In Linus' tree you can find the following new-style drivers:
drivers/rtc/rtc-ds1307.c
drivers/rtc/rtc-ds1374.c
drivers/rtc/rtc-m41t80.c
drivers/rtc/rtc-rs5c372.c

You may also take a look at one that was submitted for merge:
http://marc.info/?l=linux-kernel&m=119956436514432&w=2

This doesn't have to be done now though, if you prefer to submit your
driver as-is for now and convert it later, that's fine with me.

> Since I've dropped Thunderbird I hope the patch mangling will be
> fixed.

Yes formatting looks OK this time.

Overall your driver looks good, I only have minor remarks:

> diff -uprN -X linux-2.6.24-rc6/Documentation/dontdiff linux-2.6.24-rc6/Documentation/hwmon/ads7828 linux-2.6.24-rc6-ads7828/Documentation/hwmon/ads7828
> --- linux-2.6.24-rc6/Documentation/hwmon/ads7828	1970-01-01 01:00:00.000000000 +0100
> +++ linux-2.6.24-rc6-ads7828/Documentation/hwmon/ads7828	2008-01-02 16:30:39.000000000 +0000
> @@ -0,0 +1,38 @@
> +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 :

No space before colon.

> +               http://focus.ti.com/lit/ds/symlink/ads7828.pdf
> +
> +Authors:
> +        Steve Hardy <steve@linuxrealtime.co.uk>
> +
> +Module Parameters
> +-----------------
> +
> +* 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

2.5V

As far as I know boolean parameters take values 0 and 1, not N and Y.

> +* vref_mv: int (default 2500)
> +  If using an external reference, set this to the reference voltage in mv

Correct unit spelling is "mV".

> +
> +Description
> +-----------
> +
> +This driver implements support for the Texas Instruments ADS7828.
> +
> +This device is a 12bit 8ch A-D converter.

12-bit 8-channel

> +
> +It can operate in single ended mode (8 +ve inputs) or in differential mode,
> +when 4 differential pairs can be measured.

s/when/where/?

If there are only 4 measurement channels in differential mode, then
ideally your driver should only create 4 sysfs files in this mode, and
it should only read 4 values from the chip rather than 8 in the update
function. I2C transactions aren't cheap.

> +
> +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

5V

> +the datasheet for more details.
> +
> +

You can drop these extra blank lines.

> diff -uprN -X linux-2.6.24-rc6/Documentation/dontdiff linux-2.6.24-rc6/drivers/hwmon/Kconfig linux-2.6.24-rc6-ads7828/drivers/hwmon/Kconfig
> --- linux-2.6.24-rc6/drivers/hwmon/Kconfig	2008-01-02 16:37:43.000000000 +0000
> +++ linux-2.6.24-rc6-ads7828/drivers/hwmon/Kconfig	2008-01-02 16:49:42.000000000 +0000
> @@ -588,6 +588,16 @@ config SENSORS_SMSC47B397
>  	  This driver can also be built as a module.  If so, the module
>  	  will be called smsc47b397.
>  
> +config SENSORS_ADS7828
> +	tristate "Texas Instruments ADS7828"
> +	depends on I2C
> +	help
> +	If you say yes here you get support for Texas Instruments ADS7828
> +	12-bit 8-channel ADC device.
> +
> +	This driver can also be built as a module.  If so, the module
> +	will be called ads7828.

The help block is traditionally indented with two extra spaces.

> +
>  config SENSORS_THMC50
>  	tristate "Texas Instruments THMC50 / Analog Devices ADM1022"
>  	depends on I2C && EXPERIMENTAL
> diff -uprN -X linux-2.6.24-rc6/Documentation/dontdiff linux-2.6.24-rc6/drivers/hwmon/Makefile linux-2.6.24-rc6-ads7828/drivers/hwmon/Makefile
> --- linux-2.6.24-rc6/drivers/hwmon/Makefile	2008-01-02 16:37:43.000000000 +0000
> +++ linux-2.6.24-rc6-ads7828/drivers/hwmon/Makefile	2008-01-02 16:35:27.000000000 +0000
> @@ -22,6 +22,7 @@ obj-$(CONFIG_SENSORS_ADM1026)	+= adm1026
>  obj-$(CONFIG_SENSORS_ADM1029)	+= adm1029.o
>  obj-$(CONFIG_SENSORS_ADM1031)	+= adm1031.o
>  obj-$(CONFIG_SENSORS_ADM9240)	+= adm9240.o
> +obj-$(CONFIG_SENSORS_ADS7828)	+= ads7828.o
>  obj-$(CONFIG_SENSORS_ADT7470)	+= adt7470.o
>  obj-$(CONFIG_SENSORS_APPLESMC)	+= applesmc.o
>  obj-$(CONFIG_SENSORS_AMS)	+= ams/
> diff -uprN -X linux-2.6.24-rc6/Documentation/dontdiff linux-2.6.24-rc6/drivers/hwmon/ads7828.c linux-2.6.24-rc6-ads7828/drivers/hwmon/ads7828.c
> --- linux-2.6.24-rc6/drivers/hwmon/ads7828.c	1970-01-01 01:00:00.000000000 +0100
> +++ linux-2.6.24-rc6-ads7828/drivers/hwmon/ads7828.c	2008-01-02 16:35:27.000000000 +0000
> @@ -0,0 +1,296 @@
> +/*
> +	ads7828.c - lm_sensors driver for ads7828 12bit 8ch ADC
> +	(C) 2007 EADS Astrium
> +
> +	This driver is based on the lm75 and other lm_sensors/hwmon drivers
> +
> +	Written by Steve Hardy <steve@linuxrealtime.co.uk>
> +
> +	Datasheet available at : http://focus.ti.com/lit/ds/symlink/ads7828.pdf

No space before colon.

> +
> +	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/jiffies.h>
> +#include <linux/i2c.h>
> +#include <linux/hwmon.h>
> +#include <linux/hwmon-sysfs.h>
> +#include <linux/err.h>
> +#include <linux/mutex.h>
> +
> +/* The ADS7828 registers */
> +#define ADS7828_NCH 8 /* 8 channels of 12bit 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 */

2.5V

> +
> +/* Addresses to scan */
> +static unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b,
> +	I2C_CLIENT_END };
> +
> +/* Insmod parameters */
> +I2C_CLIENT_INSMOD_1(ads7828);
> +
> +/* Other module parameters */
> +static int se_input = 1; /* Default is SE, 0 == diff */
> +static int int_vref = 1; /* Default is internal ref ON */
> +static int vref_mv = ADS7828_INT_VREF_MV; /* set if vref != 2.5v */

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 */
> +struct ads7828_data {
> +	struct i2c_client client;
> +	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 12bit samples */

12-bit

> +};
> +
> +/* Function declaration - neccesary due to function dependencies */

Spelling: necessary.

> +static int ads7828_detect(struct i2c_adapter *adapter, int address, int kind);
> +
> +/* The ADS7828 returns the 12bit sample in two bytes,
> +	these are read as a word then byte-swapped */
> +static u16 ads7828_read_value(struct i2c_client *client, u8 reg)
> +{
> +	return swab16(i2c_smbus_read_word_data(client, reg));
> +}
> +
> +static inline u8 channel_cmd_byte(int ch)
> +{
> +	/* cmd byte C2,C1,C0 - see datasheet */
> +	u8 cmd = (((ch>>1) | (ch&0x01)<<2)<<4);
> +	cmd |= ads7828_cmd_byte;
> +	return cmd;
> +}
> +
> +/* Update data for the device (all 8 channels) */
> +static struct ads7828_data *ads7828_update_device(struct device *dev)
> +{
> +	struct i2c_client *client = to_i2c_client(dev);
> +	struct ads7828_data *data = i2c_get_clientdata(client);
> +
> +	mutex_lock(&data->update_lock);
> +
> +	if (time_after(jiffies, data->last_updated + HZ + HZ / 2)
> +			|| !data->valid) {

Note: depending on your application, this caching behavior may or may
not be desirable. It's convenient for PC drivers to prevent users from
saturating the SMBus, but for embedded designs it might cause trouble.
You might want to lower the cache lifetime or even disable the caching
behavior to always get real-time measurements.

> +		unsigned int ch;
> +		dev_dbg(&client->dev, "Starting ads7828 update\n");
> +
> +		for (ch = 0; ch < ADS7828_NCH; ch++) {
> +			u8 cmd = channel_cmd_byte(ch);
> +			data->adc_input[ch] = ads7828_read_value(client, cmd);
> +		}
> +		data->last_updated = jiffies;
> +		data->valid = 1;
> +	}
> +
> +	mutex_unlock(&data->update_lock);
> +
> +	return data;
> +}
> +
> +/* sysfs callback function */
> +static ssize_t 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) */

mV

> +	return sprintf(buf, "%d\n", (data->adc_input[attr->index] *
> +		ads7828_lsb_resol)/1000);
> +}
> +
> +#define in_reg(offset)\
> +static SENSOR_DEVICE_ATTR(in##offset##_input, S_IRUGO, show_in,\
> +	NULL, offset);

Trailing semi-colon is not needed.

> +
> +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 struct attribute *ads7828_attributes[] = {
> +	&sensor_dev_attr_in0_input.dev_attr.attr,
> +	&sensor_dev_attr_in1_input.dev_attr.attr,
> +	&sensor_dev_attr_in2_input.dev_attr.attr,
> +	&sensor_dev_attr_in3_input.dev_attr.attr,
> +	&sensor_dev_attr_in4_input.dev_attr.attr,
> +	&sensor_dev_attr_in5_input.dev_attr.attr,
> +	&sensor_dev_attr_in6_input.dev_attr.attr,
> +	&sensor_dev_attr_in7_input.dev_attr.attr,
> +	NULL
> +};
> +
> +static const struct attribute_group ads7828_group = {
> +	.attrs = ads7828_attributes,
> +};
> +
> +static int ads7828_attach_adapter(struct i2c_adapter *adapter)
> +{
> +	if (!(adapter->class & I2C_CLASS_HWMON))
> +		return 0;
> +	return i2c_probe(adapter, &addr_data, ads7828_detect);
> +}
> +
> +static int ads7828_detach_client(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);
> +	i2c_detach_client(client);
> +	kfree(i2c_get_clientdata(client));
> +	return 0;
> +}
> +
> +/* This is the driver that will be inserted */
> +static struct i2c_driver ads7828_driver = {
> +	.driver = {
> +		.name = "ads7828",
> +	},
> +	.attach_adapter = ads7828_attach_adapter,
> +	.detach_client = ads7828_detach_client,
> +};
> +
> +/* This function is called by i2c_detect */

Actually not, it's called by i2c_probe.

> +static int ads7828_detect(struct i2c_adapter *adapter, int address, int kind)
> +{
> +	struct i2c_client *client;
> +	struct ads7828_data *data;
> +	int err=0;
> +	const char *name = "";
> +
> +	/* Check we have a valid client */
> +	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_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 ads7828_read_value. */

Strange indentation...

> +	data = kzalloc(sizeof(struct ads7828_data), GFP_KERNEL);
> +	if (!data) {
> +		err = -ENOMEM;
> +		goto exit;
> +	}
> +
> +	client = &data->client;
> +	i2c_set_clientdata(client, data);
> +	client->addr = address;
> +	client->adapter = adapter;
> +	client->driver = &ads7828_driver;
> +
> +	/* 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)
> +	*/
> +	if (kind < 0) {
> +		int ch;
> +		for (ch = 0; ch < ADS7828_NCH; ch++) {
> +			u16 in_data;
> +			u8 cmd = channel_cmd_byte(ch);
> +			in_data = ads7828_read_value(client, cmd);
> +			if (in_data & 0xF000) {
> +				printk(KERN_DEBUG 
> +				"%s : Doesn't look like an ads7828 device\n",
> +				__FUNCTION__);
> +				goto exit_free;
> +			}
> +		}
> +	}
> +
> +	/* Determine the chip type - only one kind supported! */
> +	if (kind <= 0)
> +		kind = ads7828;
> +
> +	if (kind == ads7828)
> +		name = "ads7828";
> +
> +	/* Fill in the remaining client fields, put it into the global list */
> +	strlcpy(client->name, name, I2C_NAME_SIZE);
> +
> +	mutex_init(&data->update_lock);
> +
> +	/* Tell the I2C layer a new client has arrived */
> +	err = i2c_attach_client(client);
> +	if (err)
> +		goto exit_free;
> +
> +	/* Register sysfs hooks */
> +	err = sysfs_create_group(&client->dev.kobj, &ads7828_group);
> +	if (err)
> +		goto exit_detach;
> +
> +	data->hwmon_dev = hwmon_device_register(&client->dev);
> +	if (IS_ERR(data->hwmon_dev)) {
> +		err = PTR_ERR(data->hwmon_dev);
> +		goto exit_remove;
> +	}
> +
> +	return 0;
> +
> +exit_remove:
> +	sysfs_remove_group(&client->dev.kobj, &ads7828_group);
> +exit_detach:
> +	i2c_detach_client(client);
> +exit_free:
> +	kfree(data);
> +exit:
> +	return err;
> +}
> +
> +static int __init sensors_ads7828_init(void)
> +{
> +	/* Initialise the command byte according to module parameters */

Spelling: Initialize.

> +	ads7828_cmd_byte = se_input ?
> +		ADS7828_CMD_SD_SE : ADS7828_CMD_SD_DIFF;
> +	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);
> +}
> +
> +static void __exit sensors_ads7828_exit(void)
> +{
> +	i2c_del_driver(&ads7828_driver);
> +}
> +
> +MODULE_AUTHOR("Steve Hardy <steve@linuxrealtime.co.uk>");
> +MODULE_DESCRIPTION("ADS7828 driver");
> +MODULE_LICENSE("GPL");
> +
> +module_init(sensors_ads7828_init);
> +module_exit(sensors_ads7828_exit);

The rest looks OK to me. I suggest that you give a try to lm-sensors
3.0.0 with this driver, that's the best way to ensure that your sysfs
interface is properly implemented.

-- 
Jean Delvare

Re: [PATCH 1/1] : hwmon - new chip driver for TI ADS7828 A-D

[Steve Hardy]

> As far as I know boolean parameters take values 0 and 1, not N and Y.

Not on the systems I am testing on (2.6.24-rc6) - the sysfs interface
displays boolean parameters as Y/N, and will accept boot parameters as
either Y/N or 0/1.  Below is a snippet from a test proving this point :

test@shtest:~$ cat /sys/module/ads7828/parameters/se_input
Y
test@shtest:~$ cat /sys/module/ads7828/parameters/int_vref
Y

after appending the ads7828.int_vref=N parameter to the kernel
command-line :

Linux 2.6.24-rc6 (shtest) (16:53 on Saturday, 05 January 2002)

login: test
test@shtest:~$ cat /sys/module/ads7828/parameters/int_vref
N

Is it more "correct" to refer to 1/0 in the documentation?
I just naturally used the same syntax provided by the sysfs nodes

Re: [PATCH 1/1] : hwmon - new chip driver for TI ADS7828 A-D

[Jean Delvare]

Hi Steve,

On Mon, 14 Jan 2008 22:28:51 +0000, Steve Hardy wrote:
> > As far as I know boolean parameters take values 0 and 1, not N and Y.
> 
> Not on the systems I am testing on (2.6.24-rc6) - the sysfs interface
> displays boolean parameters as Y/N, and will accept boot parameters as
> either Y/N or 0/1.  Below is a snippet from a test proving this point :
> 
> test@shtest:~$ cat /sys/module/ads7828/parameters/se_input
> Y
> test@shtest:~$ cat /sys/module/ads7828/parameters/int_vref
> Y
> 
> after appending the ads7828.int_vref=N parameter to the kernel
> command-line :
> 
> Linux 2.6.24-rc6 (shtest) (16:53 on Saturday, 05 January 2002)
> 
> login: test
> test@shtest:~$ cat /sys/module/ads7828/parameters/int_vref
> N

Oh. This is news to me, thanks for the information.

> Is it more "correct" to refer to 1/0 in the documentation?
> I just naturally used the same syntax provided by the sysfs nodes

Nah, just scratch this comment of mine, I just didn't know that Y/N was
working for booleans. If you prefer that to document that form that's
alright with me.

(I do believe that it was a mistake to allow two different ways to do
the same thing, but that's a different issue.)

-- 
Jean Delvare