drivers: power: lt3074: Add README for LT3074

Add README.rst documentation file for LT3074 alongside other
documentation related files.

Signed-off-by: Cedric Encarnacion <[email protected]>

doc/sphinx/source/drivers/lt3074.rst

@@ -0,0 +1 @@
+.. include:: ../../../../drivers/power/lt3074/README.rst

doc/sphinx/source/drivers_doc.rst

@@ -101,6 +101,7 @@ POWER MANAGEMENT
    drivers/ltc4162l
    drivers/ltc4296
    drivers/ltm4686
+   drivers/lt3074
    drivers/lt7170
    drivers/lt7182s
    drivers/lt8491

drivers/power/lt3074/README.rst

@@ -0,0 +1,206 @@
+LT3074 no-OS driver
+====================
+
+Supported Devices
+-----------------
+
+`LT3074 <https://www.analog.com/LT3074>`_
+
+Overview
+--------
+
+The LT3074 is a low voltage, ultralow noise, and ultrafast transient response
+linear regulator with a PMBus serial interface. The device supplies up to 3A
+with a typical dropout voltage of 45mV. 
+
+Applications
+------------
+
+LT3074
+-------
+
+* RF Power Supplies: PLLs, VCOs, Mixers, LNAs, PAs
+* High Speed/High Precision Data Converters
+* Low Noise Instrumentation
+* Post-Regulator for Switching Supplies
+* FPGA and DSP Power Supplies
+* Medical Applications
+
+LT3074 Device Configuration
+----------------------------
+
+Driver Initialization
+---------------------
+
+In order to be able to use the device, you will have to provide the support
+for the communication protocol (I2C) alongside other GPIO pins if needed in the
+specific application (depends on the way the device is used).
+
+The first API to be called is **lt3074_init**. Make sure that it return 0,
+which means that the driver was initialized correctly.
+
+The initialization API uses the device descriptor and an initialization
+parameter. The initialization parameter contains the optional GPIO pin
+parameters for interfacing with ALERT and EN pins, and configurations for packet
+error checking.
+
+Status Bytes
+------------
+
+Assertion in the status bytes/words indicates fault/warning in device input/
+output, temperature, and communication, memory and logic. These statuses can be
+accessed via the **lt3074_read_status** API.
+
+Telemetry
+---------
+
+Measurements for each output channel can be read using the
+**lt3074_read_value** API. Some telemetry values includes input/output voltage,
+input/output current, die temperature, and output power.
+
+Overvalue and Undervalue Limits Configuration
+---------------------------------------------
+
+Overvalue and undervalue limits sets the threshold at which the device voltage,
+current, and temperature must meet. When these measurements cross the limits, a
+status bit may be asserted. These limits can be configured using the
+**lt3074_set_limit** API.
+
+VOUT Margin Configuration
+-------------------------
+
+The LT3074 output voltage margin is programmable from 0% to 30%. These can be
+configured using the **lt3074_vout_margin** API.
+
+LT3074 Driver Initialization Example
+-------------------------------------
+
+.. code-block:: bash
+
+	struct lt3074_dev *lt3074_dev;
+	struct no_os_i2c_init_param lt3074_i2c_ip = {
+		.device_id = I2C_DEVICE_ID,
+		.max_speed_hz = 100000,
+		.platform_ops = I2C_OPS,
+		.slave_address = LT3074_PMBUS_ADDRESS,
+		.extra = I2C_EXTRA,
+        };
+
+	struct no_os_gpio_init_param lt3074_enable_ip = {
+		.port = GPIO_EN_PORT,
+		.number = GPIO_EN_NUMBER,
+		.pull = NO_OS_PULL_UP,
+		.platform_ops = GPIO_OPS,
+		.extra = GPIO_EXTRA,
+	};
+
+	struct lt3074_init_param lt3074_ip = {
+		.i2c_init = &lt3074_i2c_ip,
+		.alert_param = NULL,
+		.pg_param = NULL,
+		.en_param = lt3074_enable_ip,
+		.crc_en = false,
+	};
+
+	ret = lt3074_init(&lt3074_dev, &lt3074_ip);
+	if (ret)
+		goto error;
+
+LT3074 no-OS IIO support
+-------------------------
+
+The LT3074 IIO driver comes on top of the LT3074 driver and offers support
+for interfacing IIO clients through libiio.
+
+LT3074 IIO Device Configuration
+--------------------------------
+
+Channels
+--------
+
+The device has a total of 3 input channels and 2 output channels. The input
+consists of the input voltage, bias voltage, and the die temperature. The
+output consists of the output voltage and current.
+
+* ``vout - output voltage``
+* ``iout - output current``
+* ``vin - input voltage``
+* ``vbias - bias voltage``
+* ``temperature - die temperature``
+
+Channel Attributes
+------------------
+
+EAch channels have 2 channel attributes:
+
+* ``raw - the raw value of the channel``
+* ``scale - the scale value of the channel calculated accordingly to each specific channel using a priv``
+
+Global Attributes
+-----------------
+
+The device has a total of 12 global attributes:
+
+* ``vout_margin_low - VOUT margin low limit``
+* ``vout_margin_high - VOUT margin high limit``
+* ``vout_margin_available - Available state of the vout_margin_low and vout_margin_high``
+* ``vout_ov_warn_limit - Output overvoltage warning limit``
+* ``vout_uv_warn_limit - Output undervoltage warning limit``
+* ``iout_oc_fault_limit - Output overcurrent fault limit``
+* ``ot_warn_limit - Overtemperature warning limit``
+* ``vin_ov_warn_limit - Input overvoltage warning limit``
+* ``vin_uv_warn_limit - Input undervoltage warning limit``
+* ``vbias_ov_warn_limit - Bias overvoltage warning limit``
+* ``vbias_uv_warn_limit - Bias undervoltage warning limit``
+* ``iout_min_warn_limit - Output minimum current warning limit``
+
+Debug Attributes
+----------------
+
+The device has a total of 8 debug attributes:
+
+* ``status_byte - Status byte value``
+* ``status_vout - VOUT status byte value``
+* ``status_iout - IOUT status byte value``
+* ``status_input - INPUT status byte value``
+* ``status_mfr_specific - MFR_SPECIFIC status byte value``
+* ``status_word - Status word value``
+* ``status_temperature - TEMPERATURE status byte value of the device``
+* ``status_cml - CML status byte value of the device``
+
+LT3074 IIO Driver Initialization Example
+-----------------------------------------
+
+.. code-block:: bash
+
+	int ret;
+
+	struct lt3074_iio_desc *lt3074_iio_desc;
+	struct lt3074_iio_desc_init_param lt3074_iio_ip = {
+		.lt3074_init_param = &lt3074_ip,
+	};
+
+	struct iio_app_desc *app;
+	struct iio_app_init_param app_init_param = { 0 };
+
+	ret = lt3074_iio_init(&lt3074_iio_desc, &lt3074_iio_ip);
+	if (ret)
+		return ret;
+
+	struct iio_app_device iio_devices[] = {
+		{
+			.name = "lt3074",
+			.dev = lt3074_iio_desc,
+			.dev_descriptor = lt3074_iio_desc->iio_dev,
+		}
+	};
+
+	app_init_param.devices = iio_devices;
+	app_init_param.nb_devices = NO_OS_ARRAY_SIZE(iio_devices);
+	app_init_param.uart_init_params = lt3074_uart_ip;
+
+	ret = iio_app_init(&app, app_init_param);
+	if (ret)
+		return ret;
+
+	return iio_app_run(app);