whatcanGOwrong

go/pkg/mod/golang.org/x/exp@v0.0.0-20230224173230-c95f2b4c22f2/io/spi/devfs.go

@@ -0,0 +1,177 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build linux
+// +build linux
+
+package spi
+
+import (
+	"fmt"
+	"os"
+	"syscall"
+	"unsafe"
+
+	"golang.org/x/exp/io/spi/driver"
+)
+
+const (
+	devfs_MAGIC = 107
+
+	devfs_NRBITS   = 8
+	devfs_TYPEBITS = 8
+	devfs_SIZEBITS = 13
+	devfs_DIRBITS  = 3
+
+	devfs_NRSHIFT   = 0
+	devfs_TYPESHIFT = devfs_NRSHIFT + devfs_NRBITS
+	devfs_SIZESHIFT = devfs_TYPESHIFT + devfs_TYPEBITS
+	devfs_DIRSHIFT  = devfs_SIZESHIFT + devfs_SIZEBITS
+
+	devfs_READ  = 2
+	devfs_WRITE = 4
+)
+
+type payload struct {
+	tx       uint64
+	rx       uint64
+	length   uint32
+	speed    uint32
+	delay    uint16
+	bits     uint8
+	csChange uint8
+	txNBits  uint8
+	rxNBits  uint8
+	pad      uint16
+}
+
+// Devfs is an SPI driver that works against the devfs.
+// You need to have loaded the "spidev" Linux module to use this driver.
+type Devfs struct {
+	// Dev is the device to be opened.
+	// Device name is usually in the /dev/spidev<bus>.<chip> format.
+	// Required.
+	Dev string
+
+	// Mode is the SPI mode. SPI mode is a combination of polarity and phases.
+	// CPOL is the high order bit, CPHA is the low order. Pre-computed mode
+	// values are Mode0, Mode1, Mode2 and Mode3. The value of the mode argument
+	// can be overridden by the device's driver.
+	// Required.
+	Mode Mode
+
+	// MaxSpeed is the max clock speed (Hz) and can be overridden by the device's driver.
+	// Required.
+	MaxSpeed int64
+}
+
+// Open opens the provided device with the specified options
+// and returns a connection.
+func (d *Devfs) Open() (driver.Conn, error) {
+	f, err := os.OpenFile(d.Dev, os.O_RDWR, os.ModeDevice)
+	if err != nil {
+		return nil, err
+	}
+	conn := &devfsConn{f: f}
+	if err := conn.Configure(driver.Mode, int(d.Mode)); err != nil {
+		conn.Close()
+		return nil, err
+	}
+	if err := conn.Configure(driver.MaxSpeed, int(d.MaxSpeed)); err != nil {
+		conn.Close()
+		return nil, err
+	}
+	return conn, nil
+}
+
+type devfsConn struct {
+	f        *os.File
+	mode     uint8
+	speed    uint32
+	bits     uint8
+	delay    uint16
+	csChange uint8
+}
+
+func (c *devfsConn) Configure(k, v int) error {
+	switch k {
+	case driver.Mode:
+		m := uint8(v)
+		if err := c.ioctl(requestCode(devfs_WRITE, devfs_MAGIC, 1, 1), uintptr(unsafe.Pointer(&m))); err != nil {
+			return fmt.Errorf("error setting mode to %v: %v", m, err)
+		}
+		c.mode = m
+	case driver.Bits:
+		b := uint8(v)
+		if err := c.ioctl(requestCode(devfs_WRITE, devfs_MAGIC, 3, 1), uintptr(unsafe.Pointer(&b))); err != nil {
+			return fmt.Errorf("error setting bits per word to %v: %v", b, err)
+		}
+		c.bits = b
+	case driver.MaxSpeed:
+		s := uint32(v)
+		if err := c.ioctl(requestCode(devfs_WRITE, devfs_MAGIC, 4, 4), uintptr(unsafe.Pointer(&s))); err != nil {
+			return fmt.Errorf("error setting speed to %v: %v", s, err)
+		}
+		c.speed = s
+	case driver.Order:
+		o := uint8(v)
+		if err := c.ioctl(requestCode(devfs_WRITE, devfs_MAGIC, 2, 1), uintptr(unsafe.Pointer(&o))); err != nil {
+			return fmt.Errorf("error setting bit order to %v: %v", o, err)
+		}
+	case driver.Delay:
+		c.delay = uint16(v)
+	case driver.CSChange:
+		c.csChange = uint8(v)
+	default:
+		return fmt.Errorf("unknown key: %v", k)
+	}
+	return nil
+}
+
+func (c *devfsConn) Tx(w, r []byte) error {
+	if r == nil {
+		r = make([]byte, len(w))
+	}
+	// TODO(jbd): len(w) == len(r)?
+	// TODO(jbd): Allow nil w.
+	p := payload{
+		tx:       uint64(uintptr(unsafe.Pointer(&w[0]))),
+		rx:       uint64(uintptr(unsafe.Pointer(&r[0]))),
+		length:   uint32(len(w)),
+		speed:    c.speed,
+		delay:    c.delay,
+		bits:     c.bits,
+		csChange: c.csChange,
+	}
+	// TODO(jbd): Read from the device and fill rx.
+	return c.ioctl(msgRequestCode(1), uintptr(unsafe.Pointer(&p)))
+}
+
+func (c *devfsConn) Close() error {
+	return c.f.Close()
+}
+
+// requestCode returns the device specific request code for the specified direction,
+// type, number and size to be used in the ioctl call.
+func requestCode(dir, typ, nr, size uintptr) uintptr {
+	return (dir << devfs_DIRSHIFT) | (typ << devfs_TYPESHIFT) | (nr << devfs_NRSHIFT) | (size << devfs_SIZESHIFT)
+}
+
+// msgRequestCode returns the device specific value for the SPI
+// message payload to be used in the ioctl call.
+// n represents the number of messages.
+func msgRequestCode(n uint32) uintptr {
+	return uintptr(0x40006B00 + (n * 0x200000))
+}
+
+// ioctl makes an IOCTL on the open device file descriptor.
+func (c *devfsConn) ioctl(a1, a2 uintptr) error {
+	_, _, errno := syscall.Syscall(
+		syscall.SYS_IOCTL, c.f.Fd(), a1, a2,
+	)
+	if errno != 0 {
+		return syscall.Errno(errno)
+	}
+	return nil
+}

go/pkg/mod/golang.org/x/exp@v0.0.0-20230224173230-c95f2b4c22f2/io/spi/devfs_nonlinux.go

@@ -0,0 +1,40 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build !linux
+// +build !linux
+
+package spi
+
+import (
+	"errors"
+
+	"golang.org/x/exp/io/spi/driver"
+)
+
+// Devfs is a no-implementation of an SPI driver that works against the devfs.
+// You need to have loaded the Linux "spidev" module to use this driver.
+type Devfs struct {
+	// Dev is the device to be opened.
+	// Device name is usually in the /dev/spidev<bus>.<chip> format.
+	// Required.
+	Dev string
+
+	// Mode is the SPI mode. SPI mode is a combination of polarity and phases.
+	// CPOL is the high order bit, CPHA is the low order. Pre-computed mode
+	// values are Mode0, Mode1, Mode2 and Mode3. The value of the mode argument
+	// can be overridden by the device's driver.
+	// Required.
+	Mode Mode
+
+	// MaxSpeed is the max clock speed (Hz) and can be overridden by the device's driver.
+	// Required.
+	MaxSpeed int64
+}
+
+// Open opens the provided device with the speicifed options
+// and returns a connection.
+func (d *Devfs) Open() (driver.Conn, error) {
+	return nil, errors.New("not implemented on this platform")
+}

go/pkg/mod/golang.org/x/exp@v0.0.0-20230224173230-c95f2b4c22f2/io/spi/driver/driver.go

@@ -0,0 +1,50 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package driver contains interfaces to be implemented by various SPI implementations.
+package driver // import "golang.org/x/exp/io/spi/driver"
+
+const (
+	Mode = iota
+	Bits
+	MaxSpeed
+	Order
+	Delay
+	CSChange
+)
+
+// Opener is an interface to be implemented by the SPI driver to open
+// a connection to an SPI device.
+type Opener interface {
+	Open() (Conn, error)
+}
+
+// Conn is a connection to an SPI device.
+// TODO(jbd): Extend the interface to query configuration values.
+type Conn interface {
+	// Configure configures the SPI device.
+	//
+	// Available configuration keys are:
+	//  - Mode, the SPI mode (valid values are 0, 1, 2 and 3).
+	//  - Bits, bits per word (default is 8-bit per word).
+	//  - Speed, the max clock speed (in Hz).
+	//  - Order, bit order to be used in transfers. Zero value represents
+	//    the MSB-first, non-zero values represent LSB-first encoding.
+	//  - Delay, the pause time between frames (in usecs).
+	//    Some SPI devices require a minimum amount of wait time after
+	//    each frame write. If set, Delay amount of usecs are inserted after
+	//    each write.
+	//  - CSChange, whether to leave the device's chipselect active after a Tx.
+	//
+	// SPI devices can override these values.
+	Configure(k, v int) error
+
+	// Tx performs a SPI transaction: w is written if not nil, the result is
+	// put into r if not nil. len(w) must be equal to len(r), otherwise the
+	// driver should return an error.
+	Tx(w, r []byte) error
+
+	// Close frees the underlying resources and closes the connection.
+	Close() error
+}

go/pkg/mod/golang.org/x/exp@v0.0.0-20230224173230-c95f2b4c22f2/io/spi/example_test.go

@@ -0,0 +1,38 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package spi_test
+
+import "golang.org/x/exp/io/spi"
+
+// Example illustrates a program that drives an APA-102 LED strip.
+func Example() {
+	dev, err := spi.Open(&spi.Devfs{
+		Dev:      "/dev/spidev0.1",
+		Mode:     spi.Mode3,
+		MaxSpeed: 500000,
+	})
+	if err != nil {
+		panic(err)
+	}
+	defer dev.Close()
+
+	if err := dev.Tx([]byte{
+		0, 0, 0, 0,
+		0xff, 200, 0, 200,
+		0xff, 200, 0, 200,
+		0xe0, 200, 0, 200,
+		0xff, 200, 0, 200,
+		0xff, 8, 50, 0,
+		0xff, 200, 0, 0,
+		0xff, 0, 0, 0,
+		0xff, 200, 0, 200,
+		0xff, 0xff, 0xff, 0xff,
+		0xff, 0xff, 0xff, 0xff,
+		0xff, 0xff, 0xff, 0xff,
+		0xff, 0xff, 0xff, 0xff,
+	}, nil); err != nil {
+		panic(err)
+	}
+}

go/pkg/mod/golang.org/x/exp@v0.0.0-20230224173230-c95f2b4c22f2/io/spi/spi.go

@@ -0,0 +1,107 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package spi allows users to read from and write to an SPI device.
+//
+// # Deprecated
+//
+// This package is not maintained anymore. An actively supported cross-platform
+// alternative is https://periph.io/.
+package spi // import "golang.org/x/exp/io/spi"
+
+import (
+	"time"
+
+	"golang.org/x/exp/io/spi/driver"
+)
+
+// Mode represents the SPI mode number where clock parity (CPOL)
+// is the high order and clock edge (CPHA) is the low order bit.
+type Mode int
+
+const (
+	Mode0 = Mode(0)
+	Mode1 = Mode(1)
+	Mode2 = Mode(2)
+	Mode3 = Mode(3)
+)
+
+// Order is the bit justification to be used while transferring
+// words to the SPI device. MSB-first encoding is more popular
+// than LSB-first.
+type Order int
+
+const (
+	MSBFirst = Order(0)
+	LSBFirst = Order(1)
+)
+
+type Device struct {
+	conn driver.Conn
+}
+
+// SetMode sets the SPI mode. SPI mode is a combination of polarity and phases.
+// CPOL is the high order bit, CPHA is the low order. Pre-computed mode
+// values are Mode0, Mode1, Mode2 and Mode3.
+// The value can be changed by SPI device's driver.
+func (d *Device) SetMode(mode Mode) error {
+	return d.conn.Configure(driver.Mode, int(mode))
+}
+
+// SetMaxSpeed sets the maximum clock speed in Hz.
+// The value can be overridden by SPI device's driver.
+func (d *Device) SetMaxSpeed(speed int) error {
+	return d.conn.Configure(driver.MaxSpeed, speed)
+}
+
+// SetBitsPerWord sets how many bits it takes to represent a word, e.g. 8 represents 8-bit words.
+// The default is 8 bits per word.
+func (d *Device) SetBitsPerWord(bits int) error {
+	return d.conn.Configure(driver.Bits, bits)
+}
+
+// SetBitOrder sets the bit justification used to transfer SPI words.
+// Valid values are MSBFirst and LSBFirst.
+func (d *Device) SetBitOrder(o Order) error {
+	return d.conn.Configure(driver.Order, int(o))
+}
+
+// SetDelay sets the amount of pause will be added after each frame write.
+func (d *Device) SetDelay(t time.Duration) error {
+	return d.conn.Configure(driver.Delay, int(t.Nanoseconds()/1000))
+}
+
+// SetCSChange sets whether to leave the chipselect enabled after a Tx.
+func (d *Device) SetCSChange(leaveEnabled bool) error {
+	v := 0
+	if leaveEnabled {
+		v = 1
+	}
+	return d.conn.Configure(driver.CSChange, v)
+}
+
+// Tx performs a duplex transmission to write w to the SPI device
+// and read len(r) bytes to r.
+// User should not mutate the w and r until this call returns.
+func (d *Device) Tx(w, r []byte) error {
+	// TODO(jbd): Allow nil w.
+	return d.conn.Tx(w, r)
+}
+
+// Open opens a device with the specified bus and chip select
+// by using the given driver. If a nil driver is provided,
+// the default driver (devfs) is used.
+
+func Open(o driver.Opener) (*Device, error) {
+	conn, err := o.Open()
+	if err != nil {
+		return nil, err
+	}
+	return &Device{conn: conn}, nil
+}
+
+// Close closes the SPI device and releases the related resources.
+func (d *Device) Close() error {
+	return d.conn.Close()
+}