The inputs can be used single ended or in certain differential combinations.
For configuration all possible combinations are mapped to 8 channels:
-0: Voltage over AIN0 and AIN1.
-1: Voltage over AIN0 and AIN3.
-2: Voltage over AIN1 and AIN3.
-3: Voltage over AIN2 and AIN3.
-4: Voltage over AIN0 and GND.
-5: Voltage over AIN1 and GND.
-6: Voltage over AIN2 and GND.
-7: Voltage over AIN3 and GND.
-
-Optional properties:
-
- - exported-channels : exported_channels is a bitmask that specifies which
- channels should be accessable by the user.
-
-Example:
-ads1015@49 {
- compatible = "ti,ads1015";
- reg = <0x49>;
- exported-channels = <0x14>;
-};
-
-In this example only channel 2 and 4 would be accessable by the user.
+ 0: Voltage over AIN0 and AIN1.
+ 1: Voltage over AIN0 and AIN3.
+ 2: Voltage over AIN1 and AIN3.
+ 3: Voltage over AIN2 and AIN3.
+ 4: Voltage over AIN0 and GND.
+ 5: Voltage over AIN1 and GND.
+ 6: Voltage over AIN2 and GND.
+ 7: Voltage over AIN3 and GND.
+
+Each channel can be configured individually:
+ - pga is the programmable gain amplifier (values are full scale)
+ 0: +/- 6.144 V
+ 1: +/- 4.096 V
+ 2: +/- 2.048 V (default)
+ 3: +/- 1.024 V
+ 4: +/- 0.512 V
+ 5: +/- 0.256 V
+ - data_rate in samples per second
+ 0: 128
+ 1: 250
+ 2: 490
+ 3: 920
+ 4: 1600 (default)
+ 5: 2400
+ 6: 3300
+
+1) The /ads1015 node
+
+ Required properties:
+
+ - compatible : must be "ti,ads1015"
+ - reg : I2C bus address of the device
+ - #address-cells : must be <1>
+ - #size-cells : must be <0>
+
+ The node contains child nodes for each channel that the platform uses.
+
+ Example ADS1015 node:
+
+ ads1015@49 {
+ compatible = "ti,ads1015";
+ reg = <0x49>;
+ #address-cells = <1>;
+ #size-cells = <0>;
+
+ [ child node definitions... ]
+ }
+
+2) channel nodes
+
+ Required properties:
+
+ - reg : the channel number
+
+ Optional properties:
+
+ - ti,gain : the programmable gain amplifier setting
+ - ti,datarate : the converter data rate
+
+ Example ADS1015 channel node:
+
+ channel@4 {
+ reg = <4>;
+ ti,gain = <3>;
+ ti,datarate = <5>;
+ };
The inputs can be used single ended or in certain differential combinations.
-The inputs can be exported to 8 sysfs input files in0_input - in7_input:
+The inputs can be made available by 8 sysfs input files in0_input - in7_input:
in0: Voltage over AIN0 and AIN1.
in1: Voltage over AIN0 and AIN3.
in2: Voltage over AIN1 and AIN3.
in6: Voltage over AIN2 and GND.
in7: Voltage over AIN3 and GND.
-Which inputs are exported can be configured using platform data or devicetree.
+Which inputs are available can be configured using platform data or devicetree.
By default all inputs are exported.
Platform Data
-------------
-In linux/i2c/ads1015.h platform data is defined as:
-
-struct ads1015_platform_data {
- unsigned int exported_channels;
-};
-
-exported_channels is a bitmask that specifies which inputs should be exported.
+In linux/i2c/ads1015.h platform data is defined, channel_data contains
+configuration data for the used input combinations:
+- pga is the programmable gain amplifier (values are full scale)
+ 0: +/- 6.144 V
+ 1: +/- 4.096 V
+ 2: +/- 2.048 V
+ 3: +/- 1.024 V
+ 4: +/- 0.512 V
+ 5: +/- 0.256 V
+- data_rate in samples per second
+ 0: 128
+ 1: 250
+ 2: 490
+ 3: 920
+ 4: 1600
+ 5: 2400
+ 6: 3300
Example:
struct ads1015_platform_data data = {
- .exported_channels = (1 << 2) | (1 << 4)
+ .channel_data = {
+ [2] = { .enabled = true, .pga = 1, .data_rate = 0 },
+ [4] = { .enabled = true, .pga = 4, .data_rate = 5 },
+ }
};
-In this case only in2_input and in4_input would be created.
+In this case only in2_input (FS +/- 4.096 V, 128 SPS) and in4_input
+(FS +/- 0.512 V, 2400 SPS) would be created.
Devicetree
----------
-The ads1015 node may have an "exported-channels" property.
-exported_channels is a bitmask that specifies which inputs should be exported.
-
-Example:
-ads1015@49 {
- compatible = "ti,ads1015";
- reg = <0x49>;
- exported-channels = < 0x14 >;
-};
-
-In this case only in2_input and in4_input would be created.
+Configuration is also possible via devicetree:
+Documentation/devicetree/bindings/hwmon/ads1015.txt
static const unsigned int fullscale_table[8] = {
6144, 4096, 2048, 1024, 512, 256, 256, 256 };
-#define ADS1015_CONFIG_CHANNELS 8
+/* Data rates in samples per second */
+static const unsigned int data_rate_table[8] = {
+ 128, 250, 490, 920, 1600, 2400, 3300, 3300 };
+
#define ADS1015_DEFAULT_CHANNELS 0xff
+#define ADS1015_DEFAULT_PGA 2
+#define ADS1015_DEFAULT_DATA_RATE 4
struct ads1015_data {
struct device *hwmon_dev;
struct mutex update_lock; /* mutex protect updates */
+ struct ads1015_channel_data channel_data[ADS1015_CHANNELS];
};
static s32 ads1015_read_reg(struct i2c_client *client, unsigned int reg)
{
u16 config;
s16 conversion;
- unsigned int pga;
- int fullscale;
- unsigned int k;
struct ads1015_data *data = i2c_get_clientdata(client);
+ unsigned int pga = data->channel_data[channel].pga;
+ int fullscale;
+ unsigned int data_rate = data->channel_data[channel].data_rate;
+ unsigned int conversion_time_ms;
int res;
mutex_lock(&data->update_lock);
- /* get fullscale voltage */
+ /* get channel parameters */
res = ads1015_read_reg(client, ADS1015_CONFIG);
if (res < 0)
goto err_unlock;
config = res;
- pga = (config >> 9) & 0x0007;
fullscale = fullscale_table[pga];
+ conversion_time_ms = DIV_ROUND_UP(1000, data_rate_table[data_rate]);
- /* set channel and start single conversion */
- config &= ~(0x0007 << 12);
- config |= (1 << 15) | (1 << 8) | (channel & 0x0007) << 12;
+ /* setup and start single conversion */
+ config &= 0x001f;
+ config |= (1 << 15) | (1 << 8);
+ config |= (channel & 0x0007) << 12;
+ config |= (pga & 0x0007) << 9;
+ config |= (data_rate & 0x0007) << 5;
- /* wait until conversion finished */
res = ads1015_write_reg(client, ADS1015_CONFIG, config);
if (res < 0)
goto err_unlock;
- for (k = 0; k < 5; ++k) {
- msleep(1);
- res = ads1015_read_reg(client, ADS1015_CONFIG);
- if (res < 0)
- goto err_unlock;
- config = res;
- if (config & (1 << 15))
- break;
- }
- if (k == 5) {
+
+ /* wait until conversion finished */
+ msleep(conversion_time_ms);
+ res = ads1015_read_reg(client, ADS1015_CONFIG);
+ if (res < 0)
+ goto err_unlock;
+ config = res;
+ if (!(config & (1 << 15))) {
+ /* conversion not finished in time */
res = -EIO;
goto err_unlock;
}
int k;
hwmon_device_unregister(data->hwmon_dev);
- for (k = 0; k < ADS1015_CONFIG_CHANNELS; ++k)
+ for (k = 0; k < ADS1015_CHANNELS; ++k)
device_remove_file(&client->dev, &ads1015_in[k].dev_attr);
kfree(data);
return 0;
}
-static unsigned int ads1015_get_exported_channels(struct i2c_client *client)
-{
- struct ads1015_platform_data *pdata = dev_get_platdata(&client->dev);
#ifdef CONFIG_OF
- struct device_node *np = client->dev.of_node;
- const __be32 *of_channels;
- int of_channels_size;
+static int ads1015_get_channels_config_of(struct i2c_client *client)
+{
+ struct ads1015_data *data = i2c_get_clientdata(client);
+ struct device_node *node;
+
+ if (!client->dev.of_node
+ || !of_get_next_child(client->dev.of_node, NULL))
+ return -EINVAL;
+
+ for_each_child_of_node(client->dev.of_node, node) {
+ const __be32 *property;
+ int len;
+ unsigned int channel;
+ unsigned int pga = ADS1015_DEFAULT_PGA;
+ unsigned int data_rate = ADS1015_DEFAULT_DATA_RATE;
+
+ property = of_get_property(node, "reg", &len);
+ if (!property || len != sizeof(int)) {
+ dev_err(&client->dev, "invalid reg on %s\n",
+ node->full_name);
+ continue;
+ }
+
+ channel = be32_to_cpup(property);
+ if (channel > ADS1015_CHANNELS) {
+ dev_err(&client->dev,
+ "invalid channel index %d on %s\n",
+ channel, node->full_name);
+ continue;
+ }
+
+ property = of_get_property(node, "ti,gain", &len);
+ if (property && len == sizeof(int)) {
+ pga = be32_to_cpup(property);
+ if (pga > 6) {
+ dev_err(&client->dev,
+ "invalid gain on %s\n",
+ node->full_name);
+ }
+ }
+
+ property = of_get_property(node, "ti,datarate", &len);
+ if (property && len == sizeof(int)) {
+ data_rate = be32_to_cpup(property);
+ if (data_rate > 7) {
+ dev_err(&client->dev,
+ "invalid data_rate on %s\n",
+ node->full_name);
+ }
+ }
+
+ data->channel_data[channel].enabled = true;
+ data->channel_data[channel].pga = pga;
+ data->channel_data[channel].data_rate = data_rate;
+ }
+
+ return 0;
+}
#endif
+static void ads1015_get_channels_config(struct i2c_client *client)
+{
+ unsigned int k;
+ struct ads1015_data *data = i2c_get_clientdata(client);
+ struct ads1015_platform_data *pdata = dev_get_platdata(&client->dev);
+
/* prefer platform data */
- if (pdata)
- return pdata->exported_channels;
+ if (pdata) {
+ memcpy(data->channel_data, pdata->channel_data,
+ sizeof(data->channel_data));
+ return;
+ }
#ifdef CONFIG_OF
- /* fallback on OF */
- of_channels = of_get_property(np, "exported-channels",
- &of_channels_size);
- if (of_channels && (of_channels_size == sizeof(*of_channels)))
- return be32_to_cpup(of_channels);
+ if (!ads1015_get_channels_config_of(client))
+ return;
#endif
/* fallback on default configuration */
- return ADS1015_DEFAULT_CHANNELS;
+ for (k = 0; k < ADS1015_CHANNELS; ++k) {
+ data->channel_data[k].enabled = true;
+ data->channel_data[k].pga = ADS1015_DEFAULT_PGA;
+ data->channel_data[k].data_rate = ADS1015_DEFAULT_DATA_RATE;
+ }
}
static int ads1015_probe(struct i2c_client *client,
{
struct ads1015_data *data;
int err;
- unsigned int exported_channels;
unsigned int k;
data = kzalloc(sizeof(struct ads1015_data), GFP_KERNEL);
mutex_init(&data->update_lock);
/* build sysfs attribute group */
- exported_channels = ads1015_get_exported_channels(client);
- for (k = 0; k < ADS1015_CONFIG_CHANNELS; ++k) {
- if (!(exported_channels & (1<<k)))
+ ads1015_get_channels_config(client);
+ for (k = 0; k < ADS1015_CHANNELS; ++k) {
+ if (!data->channel_data[k].enabled)
continue;
err = device_create_file(&client->dev, &ads1015_in[k].dev_attr);
if (err)
return 0;
exit_remove:
- for (k = 0; k < ADS1015_CONFIG_CHANNELS; ++k)
+ for (k = 0; k < ADS1015_CHANNELS; ++k)
device_remove_file(&client->dev, &ads1015_in[k].dev_attr);
exit_free:
kfree(data);
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