Higher baud rates for macOS

[tkornack]

Arbitrary baud rates—in particular 460800—are available on macOS using a special IOKit call. Kindly consider a special case ioctl call for them. Here is what pyserial does:

    IOSSIOSPEED = 0x80045402 
    class PlatformSpecific(PlatformSpecificBase):
        osx_version = os.uname()[2].split('.')
        # Tiger or above can support arbitrary serial speeds
        if int(osx_version[0]) >= 8:
            def _set_special_baudrate(self, baudrate):
                # use IOKit-specific call to set up high speeds
                buf = array.array('i', [baudrate])
                fcntl.ioctl(self.fd, IOSSIOSPEED, buf, 1)

[dcuddeback]

@tkornack Not just Mac, but Linux supports this too with a different ioctl.

[luojia65]

Any further works? :)