diff options
Diffstat (limited to '')
-rw-r--r-- | dependencies/pkg/mod/golang.org/x/exp@v0.0.0-20220613132600-b0d781184e0d/io/i2c/devfs.go | 80 |
1 files changed, 80 insertions, 0 deletions
diff --git a/dependencies/pkg/mod/golang.org/x/exp@v0.0.0-20220613132600-b0d781184e0d/io/i2c/devfs.go b/dependencies/pkg/mod/golang.org/x/exp@v0.0.0-20220613132600-b0d781184e0d/io/i2c/devfs.go new file mode 100644 index 0000000..3c7704f --- /dev/null +++ b/dependencies/pkg/mod/golang.org/x/exp@v0.0.0-20220613132600-b0d781184e0d/io/i2c/devfs.go @@ -0,0 +1,80 @@ +// 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 i2c + +import ( + "fmt" + "io" + "os" + "syscall" + + "golang.org/x/exp/io/i2c/driver" +) + +// Devfs is an I2C driver that works against the devfs. +// You need to load the "i2c-dev" kernel module to use this driver. +type Devfs struct { + // Dev is the I2C bus device, e.g. /dev/i2c-1. Required. + Dev string +} + +const ( + i2c_SLAVE = 0x0703 // TODO(jbd): Allow users to use I2C_SLAVE_FORCE? + i2c_TENBIT = 0x0704 +) + +// TODO(jbd): Support I2C_RETRIES and I2C_TIMEOUT at the driver and implementation level. + +func (d *Devfs) Open(addr int, tenbit bool) (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 tenbit { + if err := conn.ioctl(i2c_TENBIT, uintptr(1)); err != nil { + conn.Close() + return nil, fmt.Errorf("cannot enable the 10-bit address mode on bus %v: %v", d.Dev, err) + } + } + if err := conn.ioctl(i2c_SLAVE, uintptr(addr)); err != nil { + conn.Close() + return nil, fmt.Errorf("error opening the address (%v) on the bus (%v): %v", addr, d.Dev, err) + } + return conn, nil +} + +type devfsConn struct { + f *os.File +} + +func (c *devfsConn) Tx(w, r []byte) error { + if w != nil { + if _, err := c.f.Write(w); err != nil { + return err + } + c.f.Sync() + } + if r != nil { + if _, err := io.ReadFull(c.f, r); err != nil { + return err + } + } + return nil +} + +func (c *devfsConn) Close() error { + return c.f.Close() +} + +func (c *devfsConn) ioctl(arg1, arg2 uintptr) error { + if _, _, errno := syscall.Syscall(syscall.SYS_IOCTL, c.f.Fd(), arg1, arg2); errno != 0 { + return syscall.Errno(errno) + } + return nil +} |