# gizhw:bus the buses a board exposes: a serial port's speed (termios2, any rate through BOTHER), GPIO lines (the character device's chardev v2 interface: a line request, then its values), I2C transfers (I2C_RDWR), SPI transfers (SPI_IOC_MESSAGE), USB control transfers (usbfs), and CAN frames (SocketCAN, raw). The ioctl numbers and the structs are the kernel's (termios.h, gpio.h, i2c-dev.h, spidev.h, usbdevice_fs.h, can.h), checked against those headers. Every ioctl is on a Handle of gizhw:device; the CAN socket and the interface lookup are libc calls through libcCall. ```gizlang import * as Bus from "gizhw:bus"; ``` ## Types ### `I2cMessage` ```gizlang type I2cMessage = { address: i64; read: bool; length: i64; data: bytes; } ``` One I2C message: the 7-bit `address`, `read` (true: `length` bytes come back) or the `data` to write. - `address`: `i64` - `read`: `bool` - `length`: `i64` - `data`: `bytes` ### `CanFrame` ```gizlang type CanFrame = { id: i64; extended: bool; data: bytes; } ``` One CAN frame: its identifier, whether it is an extended (29-bit) one, and its data (up to 8 bytes). - `id`: `i64` - `extended`: `bool` - `data`: `bytes` ## Functions ### `termiosRate` ```gizlang function termiosRate(termios: bytes, baud: i64): bytes ``` The serial port's termios2 with the speed set: both directions at `baud`, through BOTHER. Effects: fail. ### `serialRate` ```gizlang function serialRate(h: Device.Handle, baud: i64): void throws string ``` Sets the serial port behind `h` to `baud`. Effects: fail, io. ### `lineRequest` ```gizlang function lineRequest(offset: i64, flags: i64, consumer: string): bytes ``` The request for GPIO_V2_GET_LINE: one line of the chip (its `offset`), as an input or an output, under `consumer`. Effects: fail. ### `parseLineFd` ```gizlang function parseLineFd(reply: bytes): i64 ``` The line's file descriptor in the reply to GPIO_V2_GET_LINE (at byte 588). Effects: fail. ### `valuesRequest` ```gizlang function valuesRequest(bits: i64, mask: i64): bytes ``` The request for GPIO_V2_LINE_GET/SET_VALUES: the bit values and the mask of the lines it touches (bit 0: the line). Effects: fail. ### `parseLineValue` ```gizlang function parseLineValue(reply: bytes): i64 ``` The value of the one line the reply to GPIO_V2_LINE_GET_VALUES describes: 0 or 1. Effects: fail. ### `gpioRead` ```gizlang function gpioRead(sys: System, chip: Device.Handle, offset: i64): i64 throws string ``` Reads GPIO line `offset` of the chip behind `chip` (its character device, /dev/gpiochipN): a line request, then its value. Effects: fail, io. ### `gpioWrite` ```gizlang function gpioWrite(sys: System, chip: Device.Handle, offset: i64, value: i64): void throws string ``` Sets GPIO line `offset` of the chip behind `chip` to `value` (0 or 1), as an output. Effects: fail, io. ### `i2cMessageBytes` ```gizlang function i2cMessageBytes(address: i64, flags: i64, length: i64, buffer: u64): bytes ``` One I2C message (struct i2c_msg: 16 bytes): address, flags, length, and the buffer's native address. Effects: fail. ### `i2cRdwrBytes` ```gizlang function i2cRdwrBytes(messages: u64, count: i64): bytes ``` The I2C_RDWR argument (struct i2c_rdwr_ioctl_data: 16 bytes): the messages' native address and their count. Effects: fail. ### `i2c` ```gizlang function i2c(h: Device.Handle, messages: Vec): Vec throws string ``` Runs I2C messages on the bus behind `h`, one transaction; gives each read's bytes (empty for a write). Effects: fail, io. ### `spiTransferBytes` ```gizlang function spiTransferBytes(tx: u64, rx: u64, length: i64, speed: i64, bits: i64): bytes ``` The SPI transfer (struct spi_ioc_transfer: 32 bytes): the tx and rx buffers, the length, speed and bits per word. Effects: fail. ### `spi` ```gizlang function spi(h: Device.Handle, tx: bytes, rxLength: i64, speed: i64): bytes throws string ``` One SPI transfer on the device behind `h`: `tx` out, and `rxLength` bytes back; gives those bytes. Effects: fail, io. ### `usbCtrlBytes` ```gizlang function usbCtrlBytes(requestType: i64, request: i64, value: i64, index: i64, length: i64, timeout: i64, data: u64): bytes ``` The usbfs control transfer (struct usbdevfs_ctrltransfer: 24 bytes). Effects: fail. ### `usbControl` ```gizlang function usbControl(h: Device.Handle, requestType: i64, request: i64, value: i64, index: i64, data: bytes, readLength: i64, timeout: i64): bytes throws string ``` A control transfer on the device behind `h`. A device-to-host one (requestType with the IN bit) reads `readLength` bytes back; a host-to-device one sends `data`. Gives the bytes that came back (empty for a send). Effects: fail, io. ### `canFrameBytes` ```gizlang function canFrameBytes(frame: CanFrame): bytes ``` A CAN frame as struct can_frame (16 bytes): the identifier (with the extended bit), the data length, and the data. Effects: fail. ### `parseCanFrame` ```gizlang function parseCanFrame(data: bytes): CanFrame ``` The CAN frame from its 16 bytes. Effects: fail. ### `canOpen` ```gizlang function canOpen(sys: System, name: string): Device.Handle throws string ``` The CAN interface `name` (can0) as a raw SocketCAN handle: the socket is bound to the interface. Effects: fail, io. ### `canSend` ```gizlang function canSend(h: Device.Handle, frame: CanFrame): i64 throws string ``` Sends one frame on the CAN handle; gives the bytes written (16). Effects: fail, io. ### `canReceive` ```gizlang function canReceive(h: Device.Handle): CanFrame throws string ``` Receives one frame from the CAN handle, waiting for it. Effects: fail, io.