SPI(4)

💖 SPI(4) — the Kernel Interfaces Manual page 💖

okay so this is spi(4) from the Kernel Interfaces Manual — literally the intro to machine-independent SPI bus support and drivers, bestie. 💅

🌸 NAME 🌸

spi — introduction to machine-independent SPI bus support and drivers. Yes, that's the whole vibe: the SPI bus framework plus its driver besties. 🫶

✨ SYNOPSIS ✨

spi* at mainbus?

Other attachments are machine-dependent and will depend on the bus topology of your system. See intro(4) for your system for more information. 🦋

🔥 DESCRIPTION 🔥

NetBSD includes a machine dependent SPI (Serial Peripheral Interface) bus subsystem, and several different machine-independent SPI device drivers. 👑

Your system may support additional machine-dependent SPI devices. Consult your system's intro(4) for additional information. ✨

SPI is a 4-wire synchronous full-duplex serial bus. Some systems provide support for Microwire, which is Philips' name for a strict subset of SPI, with more rigidly defined signaling. Therefore, Microwire devices are also supported by the SPI framework. 🧚

Note that when referencing SPI devices in a config(1) file, the slave must be provided, as SPI lacks any way to automatically probe devices. 💀

🎀 IOCTLS 🎀

The following ioctl(2) calls apply to SPI devices. They are defined in the header file <dev/spi/spi_io.h>:

• SPI_IOCTL_CONFIGURE (spi_ioctl_configure_t) — used to choose the operational mode and clock. The sic_mode defines polarity and phase of the clock. sic_speed is the clock speed in Hz, a value of 0 means to keep the default speed of the device. ⏰

typedef struct spi_ioctl_configure {
        int sic_addr;
        int sic_mode;
        int sic_speed;
} spi_ioctl_configure_t;

• SPI_IOCTL_TRANSFER (spi_ioctl_transfer_t) — used to handle an I/O transaction. 🫶

typedef struct spi_ioctl_transfer {
        int sit_addr;
        const void *sit_send;
        size_t sit_sendlen;
        void *sit_recv;
        size_t sit_recvlen;
} spi_ioctl_transfer_t;

🌈 HARDWARE 🌈

NetBSD includes the following machine-independent SPI drivers:

• bmx280thp(4) — Bosch BMP280 / BME280 sensor. 🫶
• m25p(4) — STMicroelectronics M25P family of NOR flash devices.
• mcp23s17gpio(4) — Microchip MCP23S17 16-bit GPIO chip.
• mcp3kadc(4) — Microchip MCP3x0x SAR analog to digital converter.
• mcp48x1dac(4) — Microchip MCP4801/MCP4811/MCP4821 digital to analog converter.
• tm121temp(4) — Texas Instruments TMP121 temperature sensor.
• scmdspi(4) — SPI frontend for the Sparkfun Serial Controlled Motor Driver.
• ssdfb(4) — OLED/PLED framebuffer modules. ✨

💜 FILES 💜

• /dev/spiu — SPI device unit u file.

⭐ SEE ALSO ⭐

• spi(9) — go read this too, bestie. iykyk. 💫

🦋 HISTORY 🦋

The machine-independent SPI framework was written by Garrett D'Amore for the Champaign-Urbana Community Wireless Network Project (CUWiN), and appeared in NetBSD 4.0. The ioctl(2) interface allowing configuration from userspace appeared in NetBSD 9.0. 👑

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okay that's the whole page, bestie — footer tea: this one's from Debian, dated February 27, 2021, and it's the SPI(4) page. bye, slay! 💖✨