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ADF4350 IIO宽带合成器Linux驱动程序

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资料介绍

This version (11 Feb 2016 20:59) was approved by Lars-Peter Clausen.The Previously approved version (20 Nov 2015 15:09) is available.

ADF4350 IIO Wideband Synthesizer Linux Driver
Source Code
- Status
- Files
Example platform device initialization
- Declaring SPI slave devices
Devicetree bindings
Adding Linux driver support
Hardware configuration
Driver testing
More Information

ADF4350 IIO Wideband Synthesizer Linux Driver

Supported Devices

Reference Circuits

Evaluation Boards

Description

This is a Linux industrial I/O (IIO) subsystem driver, targeting serial interface PLL Synthesizers. The industrial I/O subsystem provides a unified framework for drivers for many different types of converters and sensors using a number of different physical interfaces (i2c, spi, etc). See IIO for more information.

Source Code

Status

Source	Mainlined?
git	Yes

Files

Function	File
driver	drivers/iio/frequency/adf4350.c
include	include/linux/iio/frequency/adf4350.h
Documentation	Documentation/ABI/testing/sysfs-bus-iio-frequency-adf4350
Documentation	Documentation/devicetree/bindings/iio/frequency/adf4350.txt

Example platform device initialization

For compile time configuration, it’s common Linux practice to keep board- and application-specific configuration out of the main driver file, instead putting it into the board support file.

For devices on custom boards, as typical of embedded and SoC-(system-on-chip) based hardware, Linux uses platform_data to point to board-specific structures describing devices and how they are connected to the SoC. This can include available ports, chip variants, preferred modes, default initialization, additional pin roles, and so on. This shrinks the board-support packages (BSPs) and minimizes board and application specific #ifdefs in drivers.

21 Oct 2010 16:10

The reference frequency and GPIO numbers may vary between boards. The platform_data for the device's “struct device” holds this information.

/**
 * struct adf4350_platform_data - platform specific information
 * @clkin:		REFin frequency in Hz.
 * @channel_spacing:	Channel spacing in Hz (influences MODULUS).
 * @power_up_frequency:	Optional, If set in Hz the PLL tunes to the desired
 *			frequency on probe.
 * @ref_div_factor:	Optional, if set the driver skips dynamic calculation
 *			and uses this default value instead.
 * @ref_doubler_en:	Enables reference doubler.
 * @ref_div2_en:	Enables reference divider.
 * @r2_user_settings:	User defined settings for ADF4350/1 REGISTER_2.
 * @r3_user_settings:	User defined settings for ADF4350/1 REGISTER_3.
 * @r4_user_settings:	User defined settings for ADF4350/1 REGISTER_4.
 * @gpio_lock_detect:	Optional, if set with a valid GPIO number,
 *			a PLL_LOCKED device attribute is created.
 *			If not used - set to -1.
 */
 
struct adf4350_platform_data {
	unsigned long		clkin;
	unsigned long		channel_spacing;
	unsigned long long	power_up_frequency;
 
	unsigned short		ref_div_factor; /* 10-bit R counter */
	bool			ref_doubler_en;
	bool			ref_div2_en;
 
	unsigned		r2_user_settings;
	unsigned		r3_user_settings;
	unsigned		r4_user_settings;
	int			gpio_lock_detect;
};

static struct adf4350_platform_data adf4351_pdata = {
	.clkin = 10000000,
	.channel_spacing = 10000,
	.r2_user_settings = ADF4350_REG2_PD_POLARITY_POS,
			    ADF4350_REG2_CHARGE_PUMP_CURR_uA(2500),
	.r3_user_settings = ADF4350_REG3_12BIT_CLKDIV_MODE(0),
	.r4_user_settings = ADF4350_REG4_OUTPUT_PWR(0) |
			    ADF4350_REG4_MUTE_TILL_LOCK_EN,
	.gpio_lock_detect = -1,
};

Declaring SPI slave devices

Unlike PCI or USB devices, SPI devices are not enumerated at the hardware level. Instead, the software must know which devices are connected on each SPI bus segment, and what slave selects these devices are using. For this reason, the kernel code must instantiate SPI devices explicitly. The most common method is to declare the SPI devices by bus number.

This method is appropriate when the SPI bus is a system bus, as in many embedded systems, wherein each SPI bus has a number which is known in advance. It is thus possible to pre-declare the SPI devices that inhabit this bus. This is done with an array of struct spi_board_info, which is registered by calling spi_register_board_info().

For more information see: Documentation/spi/spi-summary

21 Oct 2010 16:10

Depending on the DDS IC used, you may need to set the modalias accordingly, matching your part name. It may also required to adjust max_speed_hz. Please consult the datasheet, for maximum spi clock supported by the device in question.

static struct spi_board_info board_spi_board_info[] __initdata = {
#if defined(CONFIG_ADF4350) || defined(CONFIG_ADF4350_MODULE)
	{
		.modalias = "adf4350",
		.max_speed_hz = 1000000,     /* max spi clock (SCK) speed in HZ */
		.bus_num = 0,
		.chip_select = GPIO_PF10 + MAX_CTRL_CS,	/* GPIO controlled SSEL */
		.platform_data = NULL, /* No spi_driver specific config */
		.mode = SPI_MODE_0,
	},
#endif
};

static int __init board_init(void)
{
	[--snip--]
 
	spi_register_board_info(board_spi_board_info, ARRAY_SIZE(board_spi_board_info));
 
	[--snip--]
 
	return 0;
}
arch_initcall(board_init);

Devicetree bindings

Required properties:
	- compatible: Should be one of
		* "adi,adf4350": When using the ADF4350 device
		* "adi,adf4351": When using the ADF4351 device
	- reg: SPI chip select numbert for the device
	- spi-max-frequency: Max SPI frequency to use (< 20000000)
	- clocks: From common clock binding. Clock is phandle to clock for
		ADF435x Reference Clock (CLKIN).

Optional properties:
	- gpios:	 GPIO Lock detect - If set with a valid phandle and GPIO number,
			pll lock state is tested upon read.
	- adi,channel-spacing: Channel spacing in Hz (influences MODULUS).
	- adi,power-up-frequency:	If set in Hz the PLL tunes to
			the desired frequency on probe.
	- adi,reference-div-factor: If set the driver skips dynamic calculation
			and uses this default value instead.
	- adi,reference-doubler-enable: Enables reference doubler.
	- adi,reference-div2-enable: Enables reference divider.
	- adi,phase-detector-polarity-positive-enable: Enables positive phase
			detector polarity. Default = negative.
	- adi,lock-detect-precision-6ns-enable: Enables 6ns lock detect precision.
			Default = 10ns.
	- adi,lock-detect-function-integer-n-enable: Enables lock detect
			for integer-N mode. Default = factional-N mode.
	- adi,charge-pump-current: Charge pump current in mA.
			Default = 2500mA.
	- adi,muxout-select: On chip multiplexer output selection.
			Valid values for the multiplexer output are:
			0: Three-State Output (default)
			1: DVDD
			2: DGND
			3: R-Counter output
			4: N-Divider output
			5: Analog lock detect
			6: Digital lock detect
	- adi,low-spur-mode-enable: Enables low spur mode.
			Default = Low noise mode.
	- adi,cycle-slip-reduction-enable: Enables cycle slip reduction.
	- adi,charge-cancellation-enable: Enabled charge pump
			charge cancellation for integer-N modes.
	- adi,anti-backlash-3ns-enable: Enables 3ns antibacklash pulse width
			 for integer-N modes.
	- adi,band-select-clock-mode-high-enable: Enables faster band
			selection logic.
	- adi,12bit-clk-divider: Clock divider value used when
			adi,12bit-clkdiv-mode != 0
	- adi,clk-divider-mode:
			Valid values for the clkdiv mode are:
			0: Clock divider off (default)
			1: Fast lock enable
			2: Phase resync enable
	- adi,aux-output-enable: Enables auxiliary RF output.
	- adi,aux-output-fundamental-enable: Selects fundamental VCO output on
			the auxiliary RF output. Default = Output of RF dividers.
	- adi,mute-till-lock-enable: Enables Mute-Till-Lock-Detect function.
	- adi,output-power: Output power selection.
			Valid values for the power mode are:
			0: -4dBm (default)
			1: -1dBm
			2: +2dBm
			3: +5dBm
	- adi,aux-output-power: Auxiliary output power selection.
			Valid values for the power mode are:
			0: -4dBm (default)
			1: -1dBm
			2: +2dBm
			3: +5dBm

Example:
		lo_pll0_rx_adf4351: adf4351-rx-lpc@4 {
			compatible = "adi,adf4351";
			reg = <4>;
			spi-max-frequency = <10000000>;
			clocks = <&clk0_ad9523 9>;
			clock-names = "clkin";
			adi,channel-spacing = <10000>;
			adi,power-up-frequency = <2400000000>;
			adi,phase-detector-polarity-positive-enable;
			adi,charge-pump-current = <2500>;
			adi,output-power = <3>;
			adi,mute-till-lock-enable;
		};

Adding Linux driver support

Configure kernel with “make menuconfig” (alternatively use “make xconfig” or “make qconfig”)

The ADF4350 Driver depends on CONFIG_SPI

Linux Kernel Configuration
	Device Drivers  --->
		<*>     Industrial I/O support --->
		    --- Industrial I/O support
		    -*-   Enable ring buffer support within IIO
		    -*-     Industrial I/O lock free software ring
		    -*-   Enable triggered sampling support

			          *** Phase-Locked Loop (PLL) frequency synthesizers ***

		    [--snip--]
			    <*>   Analog Devices ADF4350/ADF4351 Wideband Synthesizers
		    [--snip--]

Hardware configuration

Driver testing

Each and every IIO device, typically a hardware chip, has a device folder under /sys/bus/iio/devices/iio:deviceX. Where X is the IIO index of the device. Under every of these directory folders reside a set of files, depending on the characteristics and features of the hardware device in question. These files are consistently generalized and documented in the IIO ABI documentation. In order to determine which IIO deviceX corresponds to which hardware device, the user can read the name file /sys/bus/iio/devices/iio:deviceX/name. In case the sequence in which the iio device drivers are loaded/registered is constant, the numbering is constant and may be known in advance.

02 Mar 2011 15:16