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usb: pl2303: move the two baud rate encoding methods to separate functions
Signed-off-by: Frank Schäfer <fschaefer.oss@googlemail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Frank Schäfer
Greg Kroah-Hartman
parent
b9208c721c
commit
e917ba01d6
@ -269,115 +269,128 @@ static int pl2303_set_control_lines(struct usb_serial_port *port, u8 value)
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return retval;
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}
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static int pl2303_baudrate_encode_direct(int baud, enum pl2303_type type,
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u8 buf[4])
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{
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/*
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* NOTE: Only the values defined in baud_sup are supported !
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* => if unsupported values are set, the PL2303 seems to
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* use 9600 baud (at least my PL2303X always does)
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*/
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const int baud_sup[] = { 75, 150, 300, 600, 1200, 1800, 2400, 3600,
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4800, 7200, 9600, 14400, 19200, 28800, 38400,
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57600, 115200, 230400, 460800, 614400, 921600,
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1228800, 2457600, 3000000, 6000000 };
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int i;
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/* Set baudrate to nearest supported value */
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for (i = 0; i < ARRAY_SIZE(baud_sup); ++i) {
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if (baud_sup[i] > baud)
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break;
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}
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if (i == ARRAY_SIZE(baud_sup))
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baud = baud_sup[i - 1];
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else if (i > 0 && (baud_sup[i] - baud) > (baud - baud_sup[i - 1]))
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baud = baud_sup[i - 1];
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else
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baud = baud_sup[i];
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/* type_0, type_1 only support up to 1228800 baud */
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if (type != HX)
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baud = min_t(int, baud, 1228800);
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/* Direct (standard) baud rate encoding method */
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put_unaligned_le32(baud, buf);
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return baud;
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}
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static int pl2303_baudrate_encode_divisor(int baud, enum pl2303_type type,
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u8 buf[4])
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{
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/*
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* Divisor based baud rate encoding method
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*
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* NOTE: it's not clear if the type_0/1 chips support this method
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*
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* divisor = 12MHz * 32 / baudrate = 2^A * B
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*
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* with
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*
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* A = buf[1] & 0x0e
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* B = buf[0] + (buf[1] & 0x01) << 8
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*
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* Special cases:
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* => 8 < B < 16: device seems to work not properly
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* => B <= 8: device uses the max. value B = 512 instead
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*/
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unsigned int A, B;
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/* Respect the specified baud rate limits */
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baud = max_t(int, baud, 75);
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if (type == HX)
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baud = min_t(int, baud, 6000000);
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else
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baud = min_t(int, baud, 1228800);
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/* Determine factors A and B */
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A = 0;
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B = 12000000 * 32 / baud; /* 12MHz */
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B <<= 1; /* Add one bit for rounding */
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while (B > (512 << 1) && A <= 14) {
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A += 2;
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B >>= 2;
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}
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if (A > 14) { /* max. divisor = min. baudrate reached */
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A = 14;
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B = 512;
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/* => ~45.78 baud */
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} else {
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B = (B + 1) >> 1; /* Round the last bit */
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}
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/* Handle special cases */
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if (B == 512)
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B = 0; /* also: 1 to 8 */
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else if (B < 16)
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/*
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* NOTE: With the current algorithm this happens
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* only for A=0 and means that the min. divisor
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* (respectively: the max. baudrate) is reached.
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*/
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B = 16; /* => 24 MBaud */
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/* Encode the baud rate */
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buf[3] = 0x80; /* Select divisor encoding method */
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buf[2] = 0;
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buf[1] = (A & 0x0e); /* A */
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buf[1] |= ((B & 0x100) >> 8); /* MSB of B */
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buf[0] = B & 0xff; /* 8 LSBs of B */
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/* Calculate the actual/resulting baud rate */
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if (B <= 8)
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B = 512;
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baud = 12000000 * 32 / ((1 << A) * B);
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return baud;
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}
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static void pl2303_encode_baudrate(struct tty_struct *tty,
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struct usb_serial_port *port,
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enum pl2303_type type,
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u8 buf[4])
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{
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struct usb_serial *serial = port->serial;
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struct pl2303_serial_private *spriv = usb_get_serial_data(serial);
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int baud;
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baud = tty_get_baud_rate(tty);
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dev_dbg(&port->dev, "baud requested = %d\n", baud);
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if (!baud)
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return;
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if (spriv->type != HX || baud <= 115200) {
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/*
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* NOTE: Only the values defined in baud_sup are supported !
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* => if unsupported values are set, the PL2303 seems to
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* use 9600 baud (at least my PL2303X always does)
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*/
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const int baud_sup[] = { 75, 150, 300, 600, 1200, 1800, 2400,
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3600, 4800, 7200, 9600, 14400, 19200,
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28800, 38400, 57600, 115200, 230400,
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460800, 614400, 921600, 1228800,
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2457600, 3000000, 6000000 };
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int i;
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/* Set baudrate to nearest supported value */
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for (i = 0; i < ARRAY_SIZE(baud_sup); ++i) {
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if (baud_sup[i] > baud)
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break;
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}
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if (i == ARRAY_SIZE(baud_sup))
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baud = baud_sup[i - 1];
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else if (i > 0
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&& (baud_sup[i] - baud) > (baud - baud_sup[i - 1]))
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baud = baud_sup[i - 1];
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else
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baud = baud_sup[i];
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/* type_0, type_1 only support up to 1228800 baud */
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if (spriv->type != HX)
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baud = min_t(int, baud, 1228800);
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/* Direct (standard) baud rate encoding method */
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put_unaligned_le32(baud, buf);
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} else {
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/*
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* Divisor based baud rate encoding method
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*
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* NOTE: it's not clear if the type_0/1 chips
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* support this method
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*
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* divisor = 12MHz * 32 / baudrate = 2^A * B
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*
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* with
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*
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* A = buf[1] & 0x0e
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* B = buf[0] + (buf[1] & 0x01) << 8
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*
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* Special cases:
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* => 8 < B < 16: device seems to work not properly
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* => B <= 8: device uses the max. value B = 512 instead
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*/
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unsigned int A, B;
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/* Respect the specified baud rate limits */
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baud = max_t(int, baud, 75);
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if (spriv->type == HX)
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baud = min_t(int, baud, 6000000);
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else
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baud = min_t(int, baud, 1228800);
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/* Determine factors A and B */
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A = 0;
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B = 12000000 * 32 / baud; /* 12MHz */
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B <<= 1; /* Add one bit for rounding */
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while (B > (512 << 1) && A <= 14) {
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A += 2;
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B >>= 2;
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}
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if (A > 14) { /* max. divisor = min. baudrate reached */
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A = 14;
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B = 512;
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/* => ~45.78 baud */
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} else {
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B = (B + 1) >> 1; /* Round the last bit */
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}
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/* Handle special cases */
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if (B == 512)
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B = 0; /* also: 1 to 8 */
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else if (B < 16)
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/*
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* NOTE: With the current algorithm this happens
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* only for A=0 and means that the min. divisor
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* (respectively: the max. baudrate) is reached.
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*/
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B = 16; /* => 24 MBaud */
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/* Encode the baud rate */
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buf[3] = 0x80; /* Select divisor encoding method */
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buf[2] = 0;
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buf[1] = (A & 0x0e); /* A */
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buf[1] |= ((B & 0x100) >> 8); /* MSB of B */
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buf[0] = B & 0xff; /* 8 LSBs of B */
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/* Calculate the actual/resulting baud rate */
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if (B <= 8)
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B = 512;
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baud = 12000000 * 32 / ((1 << A) * B);
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}
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/*
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* There are two methods for setting/encoding the baud rate
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* 1) Direct method: encodes the baud rate value directly
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* => supported by all chip types
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* 2) Divisor based method: encodes a divisor to a base value (12MHz*32)
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* => supported by HX chips (and likely not by type_0/1 chips)
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*/
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if (type != HX || baud <= 115200)
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baud = pl2303_baudrate_encode_direct(baud, type, buf);
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else
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baud = pl2303_baudrate_encode_divisor(baud, type, buf);
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/* Save resulting baud rate */
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tty_encode_baud_rate(tty, baud, baud);
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dev_dbg(&port->dev, "baud set = %d\n", baud);
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@ -434,8 +447,8 @@ static void pl2303_set_termios(struct tty_struct *tty,
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dev_dbg(&port->dev, "data bits = %d\n", buf[6]);
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}
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/* For reference buf[0]:buf[3] baud rate value */
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pl2303_encode_baudrate(tty, port, &buf[0]);
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/* For reference: buf[0]:buf[3] baud rate value */
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pl2303_encode_baudrate(tty, port, spriv->type, buf);
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/* For reference buf[4]=0 is 1 stop bits */
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/* For reference buf[4]=1 is 1.5 stop bits */
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