ChangeSet 1.811.1.10, 2002/12/12 13:45:00-08:00, [EMAIL PROTECTED] [PATCH] USB: ftdi-sio update
Attached is a patch which updates ftdi sio driver with better (i.e. always correct ;-) fractional divisor code. The previous one was an oversimplification that would not always give the best approximation of the divisor. It also became an internal static function -- exposing it as a (yet another) macro was unnecessary. diff -Nru a/drivers/usb/serial/ftdi_sio.c b/drivers/usb/serial/ftdi_sio.c --- a/drivers/usb/serial/ftdi_sio.c Mon Dec 16 16:34:03 2002 +++ b/drivers/usb/serial/ftdi_sio.c Mon Dec 16 16:34:03 2002 @@ -17,6 +17,14 @@ * See http://ftdi-usb-sio.sourceforge.net for upto date testing info * and extra documentation * + * (07/Jun/2002) Kuba Ober + * Changed FTDI_SIO_BASE_BAUD_TO_DIVISOR macro into ftdi_baud_to_divisor + * function. It was getting too complex. + * Fix the divisor calculation logic which was setting divisor of 0.125 + * instead of 0.5 for fractional parts of divisor equal to 5/8, 6/8, 7/8. + * Also make it bump up the divisor to next integer in case of 7/8 - it's + * a better approximation. + * * (25/Jul/2002) Bill Ryder inserted Dmitri's TIOCMIWAIT patch * Not tested by me but it doesn't break anything I use. * @@ -203,6 +211,10 @@ static void ftdi_set_termios (struct usb_serial_port *port, struct termios * old); static int ftdi_ioctl (struct usb_serial_port *port, struct file * file, unsigned int cmd, unsigned long arg); static void ftdi_break_ctl (struct usb_serial_port *port, int break_state ); +static unsigned short int ftdi_baud_base_to_divisor + (int baud, int base); +static unsigned short int ftdi_baud_to_divisor + (int baud); static struct usb_serial_device_type ftdi_SIO_device = { .owner = THIS_MODULE, @@ -257,6 +269,23 @@ * *************************************************************************** */ +static unsigned short int ftdi_baud_base_to_divisor(int baud, int base) +{ + unsigned short int divisor; + int divisor3 = base / 2 / baud; // divisor shifted 3 bits to the left + if ((divisor3 & 0x7) == 7) divisor3 ++; // round x.7/8 up to x+1 + divisor = divisor3 >> 3; + divisor3 &= 0x7; + if (divisor3 == 1) divisor |= 0xc000; else // 0.125 + if (divisor3 >= 4) divisor |= 0x4000; else // 0.5 + if (divisor3 != 0) divisor |= 0x8000; // 0.25 + return divisor; +} + +static unsigned short int ftdi_baud_to_divisor(int baud) +{ + return(ftdi_baud_base_to_divisor(baud, 48000000)); +} static int set_rts(struct usb_device *dev, unsigned int pipe, @@ -373,7 +402,7 @@ break; case FT8U232AM: /* 8U232AM chip */ if (baud <= 3000000) { - urb_value = FTDI_SIO_BAUD_TO_DIVISOR(baud); + urb_value = ftdi_baud_to_divisor(baud); } else { dbg("%s - Baud rate too high!", __FUNCTION__); } diff -Nru a/drivers/usb/serial/ftdi_sio.h b/drivers/usb/serial/ftdi_sio.h --- a/drivers/usb/serial/ftdi_sio.h Mon Dec 16 16:34:03 2002 +++ b/drivers/usb/serial/ftdi_sio.h Mon Dec 16 16:34:03 2002 @@ -125,17 +125,9 @@ ftdi_sio_b115200 = 9 } FTDI_SIO_baudrate_t ; -#define FTDI_SIO_BASE_BAUD_TO_DIVISOR(base, baud) ( \ -((base/2/baud) >> 3) | \ -(((base/2/baud) & 2) ? 0x8000 : 0) | \ -(((base/2/baud) & 4) ? 0x4000 : 0) | \ -((((base/2/baud) & 0x7) == 1) ? 0xc000 : 0) ) - -#define FTDI_SIO_BAUD_TO_DIVISOR(baud) FTDI_SIO_BASE_BAUD_TO_DIVISOR(48000000, baud) - /* - * The ftdi_8U232AM_xxMHz_byyy constans have been removed. Their values can - * be calculated as follows: FTDI_SIO_BAUD_TO_DIVISOR(xx000000, yyy) + * The ftdi_8U232AM_xxMHz_byyy constants have been removed. The encoded divisor values + * are calculated internally. */ #define FTDI_SIO_SET_DATA_REQUEST FTDI_SIO_SET_DATA ------------------------------------------------------- This sf.net email is sponsored by: With Great Power, Comes Great Responsibility Learn to use your power at OSDN's High Performance Computing Channel http://hpc.devchannel.org/ _______________________________________________ [EMAIL PROTECTED] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
