[v4] hwmon: ads7828 optional parameters from the device tree

Submitted by Sam Povilus on March 19, 2017, 7:38 p.m.

Details

Message ID 20170319193858.24981-1-kernel.development@povil.us
State Not Applicable
Headers show

Commit Message

Sam Povilus March 19, 2017, 7:38 p.m.
Adding the ability for the ads7828 and ads7830 to use the device tree to
get their optional parameters, instead of using platform devices. This
allows people using custom boards to also use the ads7828 in a non-default
manner.

Because we have made it easy for the user to specify an improper reference
voltage, adding a note to the user if they misconfigure the device's
external reference.

v2: conforming to coding style
v3: changing from "_" to "-" for device tree entries
v4: using regulator subsystem for voltage source, renaming differential input
    property

Signed-off-by: Sam Povilus <kernel.development@povil.us>
---
 .../devicetree/bindings/hwmon/ads7828.txt          | 27 ++++++++++++++++++++++
 .../devicetree/bindings/i2c/trivial-devices.txt    |  2 --
 drivers/hwmon/ads7828.c                            | 23 ++++++++++++++++++
 3 files changed, 50 insertions(+), 2 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/hwmon/ads7828.txt

Comments

Guenter Roeck March 19, 2017, 11:54 p.m.
On 03/19/2017 12:38 PM, Sam Povilus wrote:
> Adding the ability for the ads7828 and ads7830 to use the device tree to
> get their optional parameters, instead of using platform devices. This
> allows people using custom boards to also use the ads7828 in a non-default
> manner.
>
> Because we have made it easy for the user to specify an improper reference
> voltage, adding a note to the user if they misconfigure the device's
> external reference.
>
> v2: conforming to coding style
> v3: changing from "_" to "-" for device tree entries
> v4: using regulator subsystem for voltage source, renaming differential input
>     property
>
> Signed-off-by: Sam Povilus <kernel.development@povil.us>
> ---
>  .../devicetree/bindings/hwmon/ads7828.txt          | 27 ++++++++++++++++++++++
>  .../devicetree/bindings/i2c/trivial-devices.txt    |  2 --
>  drivers/hwmon/ads7828.c                            | 23 ++++++++++++++++++
>  3 files changed, 50 insertions(+), 2 deletions(-)
>  create mode 100644 Documentation/devicetree/bindings/hwmon/ads7828.txt
>
> diff --git a/Documentation/devicetree/bindings/hwmon/ads7828.txt b/Documentation/devicetree/bindings/hwmon/ads7828.txt
> new file mode 100644
> index 000000000000..c71b4005e045
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/hwmon/ads7828.txt
> @@ -0,0 +1,27 @@
> +ads7828 properties
> +
> +Required properties:
> +- compatible:

compatible

> +	Should be one of
> +	       ti,ads7828
> +	       ti,ads7830
> +- reg: I2C address
> +
> +Optional properties:
> +
> +- ti,differential-input
> +  Set to use the device in differential mode.
> +- vref
> +  The external reference on the device is set to this regulators output. If it
> +  does not exists the internal reference will be used and output by the ads78xx
> +  on the "external vref" pin.
> +
> +  Example ADS7828 node:
> +
> +  ads7828: ads@48 {
> +  	   comatible = "ti,ads7828";
> +	   reg = <0x48>;
> +	   vref = <&vref>;

Shouldn't this be vref-supply ?

> +	   ti,differential-input;
> +  };
> +
> diff --git a/Documentation/devicetree/bindings/i2c/trivial-devices.txt b/Documentation/devicetree/bindings/i2c/trivial-devices.txt
> index cdd7b48826c3..87648909f6ce 100644
> --- a/Documentation/devicetree/bindings/i2c/trivial-devices.txt
> +++ b/Documentation/devicetree/bindings/i2c/trivial-devices.txt
> @@ -163,8 +163,6 @@ st,m41t00		Serial real-time clock (RTC)
>  st,m41t62		Serial real-time clock (RTC) with alarm
>  st,m41t80		M41T80 - SERIAL ACCESS RTC WITH ALARMS
>  taos,tsl2550		Ambient Light Sensor with SMBUS/Two Wire Serial Interface
> -ti,ads7828		8-Channels, 12-bit ADC
> -ti,ads7830		8-Channels, 8-bit ADC
>  ti,tsc2003		I2C Touch-Screen Controller
>  ti,tmp102		Low Power Digital Temperature Sensor with SMBUS/Two Wire Serial Interface
>  ti,tmp103		Low Power Digital Temperature Sensor with SMBUS/Two Wire Serial Interface
> diff --git a/drivers/hwmon/ads7828.c b/drivers/hwmon/ads7828.c
> index ee396ff167d9..4f64141b2997 100644
> --- a/drivers/hwmon/ads7828.c
> +++ b/drivers/hwmon/ads7828.c
> @@ -34,6 +34,7 @@
>  #include <linux/platform_data/ads7828.h>
>  #include <linux/regmap.h>
>  #include <linux/slab.h>
> +#include <linux/regulator/consumer.h>
>
>  /* The ADS7828 registers */
>  #define ADS7828_CMD_SD_SE	0x80	/* Single ended inputs */
> @@ -118,9 +119,13 @@ static int ads7828_probe(struct i2c_client *client,
>  	struct ads7828_data *data;
>  	struct device *hwmon_dev;
>  	unsigned int vref_mv = ADS7828_INT_VREF_MV;
> +	unsigned int vref_mv_tmp;
> +	unsigned int vref_uv = -1;

unsigned and -1 doesn't fit well together. Either case, the initialization is unnecessary.

>  	bool diff_input = false;
>  	bool ext_vref = false;
>  	unsigned int regval;
> +	struct regulator *reg;
> +
>
>  	data = devm_kzalloc(dev, sizeof(struct ads7828_data), GFP_KERNEL);
>  	if (!data)
> @@ -131,11 +136,29 @@ static int ads7828_probe(struct i2c_client *client,
>  		ext_vref = pdata->ext_vref;
>  		if (ext_vref && pdata->vref_mv)
>  			vref_mv = pdata->vref_mv;
> +	} else if (dev->of_node) {
> +		if (of_get_property(dev->of_node, "ti,differential-input",
> +				    NULL))
> +			diff_input = true;
> +		reg = devm_regulator_get_optional(dev, "vref");
> +		if (!IS_ERR(reg)) {
> +			vref_uv = regulator_get_voltage(reg);
> +			if (vref_uv >= 0) {

This is always >= 0 since vref_uv is defined as unsigned int.

> +				vref_mv = DIV_ROUND_CLOSEST(vref_uv, 1000);
> +				ext_vref = true;
> +			}
> +		}
>  	}
>
>  	/* Bound Vref with min/max values */
> +	vref_mv_tmp = vref_mv;
>  	vref_mv = clamp_val(vref_mv, ADS7828_EXT_VREF_MV_MIN,
>  			    ADS7828_EXT_VREF_MV_MAX);
> +	if (vref_mv_tmp != vref_mv) {
> +		pr_info("You used and invalid external reference voltage, it has"
> +			" been clamped to %u mV",

I would prefer if the devicetree code above would check the range
and return -EINVAL if it is bad. Clamping doesn't really make any sense here,
since the result is wrong. If you want an error message with that, please
use dev_err and shorten the message ("Invalid external reference voltage").

> +			vref_mv);
> +	}
>
>  	/* ADS7828 uses 12-bit samples, while ADS7830 is 8-bit */
>  	if (id->driver_data == ads7828) {
>

--
To unsubscribe from this list: send the line "unsubscribe linux-i2c" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Patch hide | download patch | download mbox

diff --git a/Documentation/devicetree/bindings/hwmon/ads7828.txt b/Documentation/devicetree/bindings/hwmon/ads7828.txt
new file mode 100644
index 000000000000..c71b4005e045
--- /dev/null
+++ b/Documentation/devicetree/bindings/hwmon/ads7828.txt
@@ -0,0 +1,27 @@ 
+ads7828 properties
+
+Required properties:
+- compatible:
+	Should be one of
+	       ti,ads7828
+	       ti,ads7830
+- reg: I2C address
+
+Optional properties:
+
+- ti,differential-input
+  Set to use the device in differential mode.
+- vref
+  The external reference on the device is set to this regulators output. If it
+  does not exists the internal reference will be used and output by the ads78xx
+  on the "external vref" pin.
+
+  Example ADS7828 node:
+
+  ads7828: ads@48 {
+  	   comatible = "ti,ads7828";
+	   reg = <0x48>;
+	   vref = <&vref>;
+	   ti,differential-input;
+  };
+
diff --git a/Documentation/devicetree/bindings/i2c/trivial-devices.txt b/Documentation/devicetree/bindings/i2c/trivial-devices.txt
index cdd7b48826c3..87648909f6ce 100644
--- a/Documentation/devicetree/bindings/i2c/trivial-devices.txt
+++ b/Documentation/devicetree/bindings/i2c/trivial-devices.txt
@@ -163,8 +163,6 @@  st,m41t00		Serial real-time clock (RTC)
 st,m41t62		Serial real-time clock (RTC) with alarm
 st,m41t80		M41T80 - SERIAL ACCESS RTC WITH ALARMS
 taos,tsl2550		Ambient Light Sensor with SMBUS/Two Wire Serial Interface
-ti,ads7828		8-Channels, 12-bit ADC
-ti,ads7830		8-Channels, 8-bit ADC
 ti,tsc2003		I2C Touch-Screen Controller
 ti,tmp102		Low Power Digital Temperature Sensor with SMBUS/Two Wire Serial Interface
 ti,tmp103		Low Power Digital Temperature Sensor with SMBUS/Two Wire Serial Interface
diff --git a/drivers/hwmon/ads7828.c b/drivers/hwmon/ads7828.c
index ee396ff167d9..4f64141b2997 100644
--- a/drivers/hwmon/ads7828.c
+++ b/drivers/hwmon/ads7828.c
@@ -34,6 +34,7 @@ 
 #include <linux/platform_data/ads7828.h>
 #include <linux/regmap.h>
 #include <linux/slab.h>
+#include <linux/regulator/consumer.h>
 
 /* The ADS7828 registers */
 #define ADS7828_CMD_SD_SE	0x80	/* Single ended inputs */
@@ -118,9 +119,13 @@  static int ads7828_probe(struct i2c_client *client,
 	struct ads7828_data *data;
 	struct device *hwmon_dev;
 	unsigned int vref_mv = ADS7828_INT_VREF_MV;
+	unsigned int vref_mv_tmp;
+	unsigned int vref_uv = -1;
 	bool diff_input = false;
 	bool ext_vref = false;
 	unsigned int regval;
+	struct regulator *reg;
+
 
 	data = devm_kzalloc(dev, sizeof(struct ads7828_data), GFP_KERNEL);
 	if (!data)
@@ -131,11 +136,29 @@  static int ads7828_probe(struct i2c_client *client,
 		ext_vref = pdata->ext_vref;
 		if (ext_vref && pdata->vref_mv)
 			vref_mv = pdata->vref_mv;
+	} else if (dev->of_node) {
+		if (of_get_property(dev->of_node, "ti,differential-input",
+				    NULL))
+			diff_input = true;
+		reg = devm_regulator_get_optional(dev, "vref");
+		if (!IS_ERR(reg)) {
+			vref_uv = regulator_get_voltage(reg);
+			if (vref_uv >= 0) {
+				vref_mv = DIV_ROUND_CLOSEST(vref_uv, 1000);
+				ext_vref = true;
+			}
+		}
 	}
 
 	/* Bound Vref with min/max values */
+	vref_mv_tmp = vref_mv;
 	vref_mv = clamp_val(vref_mv, ADS7828_EXT_VREF_MV_MIN,
 			    ADS7828_EXT_VREF_MV_MAX);
+	if (vref_mv_tmp != vref_mv) {
+		pr_info("You used and invalid external reference voltage, it has"
+			" been clamped to %u mV",
+			vref_mv);
+	}
 
 	/* ADS7828 uses 12-bit samples, while ADS7830 is 8-bit */
 	if (id->driver_data == ads7828) {