Re: [PATCH] hwmon: (ads1015) Make gain and datarate configurable

[Grant Likely <grant.likely@secretlab.ca>]

On Wed, Mar 09, 2011 at 02:52:40PM +0100, Dirk Eibach wrote:
> Signed-off-by: Dirk Eibach <eibach@gdsys.de>

Hi Dirk,

Patches need a description.  Very seldom is the patch title
sufficient, and usually only for trivial stuff.  Tell us some details
about what the patch does and what testing has been performed on it.

> ---
>  .../devicetree/bindings/hwmon/ads1015.txt          |   73 ++++++++++++++
>  Documentation/devicetree/bindings/i2c/ads1015.txt  |   29 ------

Huh?  What tree is this patch committed against?  If this is a
follow-on to a previous patch, then the patch description should
detail that information.

>  Documentation/hwmon/ads1015                        |   48 +++++++---
>  drivers/hwmon/ads1015.c                            |  104 ++++++++++++++++----
>  include/linux/i2c/ads1015.h                        |    8 ++
>  5 files changed, 202 insertions(+), 60 deletions(-)
>  create mode 100644 Documentation/devicetree/bindings/hwmon/ads1015.txt
>  delete mode 100644 Documentation/devicetree/bindings/i2c/ads1015.txt
> 
> diff --git a/Documentation/devicetree/bindings/hwmon/ads1015.txt b/Documentation/devicetree/bindings/hwmon/ads1015.txt
> new file mode 100644
> index 0000000..fb6e139
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/hwmon/ads1015.txt
> @@ -0,0 +1,73 @@
> +ADS1015 (I2C)
> +
> +This device is a 12-bit A-D converter with 4 inputs.
> +
> +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.
> +
> +Each channel can be configured indvidually:
> + - pga ist the programmable gain amplifier
> +    0: FS = +/- 6.144 V
> +    1: FS = +/- 4.096 V
> +    2: FS = +/- 2.048 V (default)
> +    3: FS = +/- 1.024 V
> +    4: FS = +/- 0.512 V
> +    5: FS = +/- 0.256 V
> + - data_rate in samples per second
> +    0: 128
> +    1: 250
> +    2: 490
> +    3: 920
> +    4: 1600
> +    5: 2400
> +    6: 3300
> +
> +1) The /ads1015 node
> +
> +  Required properties:
> +
> +   - compatible : must be "ti,ads1015"
> +   - reg : I2C busaddress 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 datarate
> +
> +  Example ADS1015 node:
> +
> +    channel@4 {
> +	    reg = <4>;
> +	    ti,gain = <3>;
> +	    ti,datarate = <5>;
> +    };

Binding looks good to me.

> diff --git a/Documentation/devicetree/bindings/i2c/ads1015.txt b/Documentation/devicetree/bindings/i2c/ads1015.txt
> deleted file mode 100644
> index 985e24d..0000000
> --- a/Documentation/devicetree/bindings/i2c/ads1015.txt
> +++ /dev/null
> @@ -1,29 +0,0 @@
> -ADS1015 (I2C)
> -
> -This device is a 12-bit A-D converter with 4 inputs.
> -
> -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 accessible by the user.
> -
> -Example:
> -ads1015@49 {
> -	compatible = "ti,ads1015";
> -	reg = <0x49>;
> -	exported-channels = <0x14>;
> -};
> -
> -In this example only channel 2 and 4 would be accessible by the user.
> diff --git a/Documentation/hwmon/ads1015 b/Documentation/hwmon/ads1015
> index 56ee797..30250ca 100644
> --- a/Documentation/hwmon/ads1015
> +++ b/Documentation/hwmon/ads1015
> @@ -38,30 +38,52 @@ Platform Data
>  
>  In linux/i2c/ads1015.h platform data is defined as:
>  
> +struct ads1015_channel_data {
> +	unsigned int pga;
> +	unsigned int data_rate;
> +};
> +
>  struct ads1015_platform_data {
>  	unsigned int exported_channels;
> +	struct ads1015_channel_data channel_data[ADS1015_CONFIG_CHANNELS];
>  };
>  
>  exported_channels is a bitmask that specifies which inputs should be exported.
>  
> +channel_data contains configuration data for the exported inputs:
> +- pga ist the programmable gain amplifier
> +  0: FS = +/- 6.144 V
> +  1: FS = +/- 4.096 V
> +  2: FS = +/- 2.048 V (default)
> +  3: FS = +/- 1.024 V
> +  4: FS = +/- 0.512 V
> +  5: FS = +/- 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)
> +	.exported_channels = (1 << 2) | (1 << 4),
> +	.channel_data = {
> +		{},
> +		{},
> +		{ .pga = 1, .data_rate = 0 },
> +		{},
> +		{ .pga = 4, .data_rate = 5},
> +	}

You can use explicit C99 array initializers here which would be more
concise; something like:

.channel_data = {
	[2] = { .pga = 1, .data_rate = 0 },
	[4] = { .pga = 4, .data_rate = 5 },
}

Also, would it not make sense to encode the exported_channels bit into
this array too.  Maybe something like this?

.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
> diff --git a/drivers/hwmon/ads1015.c b/drivers/hwmon/ads1015.c
> index 8ef2b60..8657863 100644
> --- a/drivers/hwmon/ads1015.c
> +++ b/drivers/hwmon/ads1015.c
> @@ -25,7 +25,7 @@
>  #include <linux/module.h>
>  #include <linux/init.h>
>  #include <linux/slab.h>
> -#include <linux/jiffies.h>
> +#include <linux/delay.h>
>  #include <linux/i2c.h>
>  #include <linux/hwmon.h>
>  #include <linux/hwmon-sysfs.h>
> @@ -45,12 +45,18 @@ enum {
>  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_CONFIG_CHANNELS];
>  };
>  
>  static s32 ads1015_read_reg(struct i2c_client *client, unsigned int reg)
> @@ -71,32 +77,38 @@ static int ads1015_read_value(struct i2c_client *client, unsigned int channel,
>  {
>  	u16 config;
>  	s16 conversion;
> -	unsigned int pga;
> +	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;
>  	unsigned int k;
> -	struct ads1015_data *data = i2c_get_clientdata(client);
>  	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 = 1 + 1000 / data_rate_table[data_rate];
>  
>  	/* set channel and start single conversion */
> -	config &= ~(0x0007 << 12);
> -	config |= (1 << 15) | (1 << 8) | (channel & 0x0007) << 12;
> +	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;
> +
> +	/* wait until conversion finished */
>  	for (k = 0; k < 5; ++k) {
> -		schedule_timeout(msecs_to_jiffies(1));
> +		msleep(k ? 1 : conversion_time_ms);
>  		res = ads1015_read_reg(client, ADS1015_CONFIG);
>  		if (res < 0)
>  			goto err_unlock;
> @@ -168,26 +180,82 @@ static int ads1015_remove(struct i2c_client *client)
>  
>  static unsigned int ads1015_get_exported_channels(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);
>  #ifdef CONFIG_OF
> -	struct device_node *np = client->dev.of_node;
> -	const __be32 *of_channels;
> -	int of_channels_size;
> +	unsigned int of_exported_channels = 0;
> +	struct device_node *node;
>  #endif
>  
>  	/* prefer platform data */
> -	if (pdata)
> +	if (pdata) {
> +		memcpy(data->channel_data, pdata->channel_data,
> +		       sizeof(data->channel_data));
>  		return pdata->exported_channels;
> +	}
>  
>  #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 (!client->dev.of_node
> +	    || !of_get_next_child(client->dev.of_node, NULL))
> +		goto fallback_default;
> +
> +	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, "ads1015: invalid reg on %s\n",
> +				node->full_name);
> +			continue;
> +		}
> +
> +		channel = be32_to_cpup(property);
> +		if (channel > ADS1015_CONFIG_CHANNELS) {
> +			dev_err(&client->dev, "ads1015: invalid addr=%x 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 > 7) {
> +				dev_err(&client->dev,
> +					"ads1015: 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,
> +					"ads1015: invalid data_rate on %s\n",
> +					node->full_name);
> +		}
> +
> +		of_exported_channels |= (1 << channel);
> +		data->channel_data[channel].pga = pga;
> +		data->channel_data[channel].data_rate = data_rate;
> +	}
> +
> +	return of_exported_channels;
>  #endif
>  
>  	/* fallback on default configuration */
> +fallback_default:
> +	for (k = 0; k < ADS1015_CONFIG_CHANNELS; ++k) {
> +		data->channel_data[k].pga = ADS1015_DEFAULT_PGA;
> +		data->channel_data[k].data_rate = ADS1015_DEFAULT_DATA_RATE;
> +	}
> +
>  	return ADS1015_DEFAULT_CHANNELS;
>  }
>  
> diff --git a/include/linux/i2c/ads1015.h b/include/linux/i2c/ads1015.h
> index 8541c6a..8f32040 100644
> --- a/include/linux/i2c/ads1015.h
> +++ b/include/linux/i2c/ads1015.h
> @@ -21,8 +21,16 @@
>  #ifndef LINUX_ADS1015_H
>  #define LINUX_ADS1015_H
>  
> +#define ADS1015_CONFIG_CHANNELS 8
> +
> +struct ads1015_channel_data {
> +	unsigned int pga;
> +	unsigned int data_rate;
> +};
> +
>  struct ads1015_platform_data {
>  	unsigned int exported_channels;
> +	struct ads1015_channel_data channel_data[ADS1015_CONFIG_CHANNELS];
>  };
>  
>  #endif /* LINUX_ADS1015_H */
> -- 
> 1.5.6.5
> 
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