diff options
Diffstat (limited to 'packages/linux/linux-rp-2.6.26/serial-add-support-for-non-standard-xtals-to-16c950-driver.patch')
| -rw-r--r-- | packages/linux/linux-rp-2.6.26/serial-add-support-for-non-standard-xtals-to-16c950-driver.patch | 155 |
1 files changed, 155 insertions, 0 deletions
diff --git a/packages/linux/linux-rp-2.6.26/serial-add-support-for-non-standard-xtals-to-16c950-driver.patch b/packages/linux/linux-rp-2.6.26/serial-add-support-for-non-standard-xtals-to-16c950-driver.patch new file mode 100644 index 0000000000..b513ba1466 --- /dev/null +++ b/packages/linux/linux-rp-2.6.26/serial-add-support-for-non-standard-xtals-to-16c950-driver.patch @@ -0,0 +1,155 @@ + +From: Petr Vandrovec <vandrove@vc.cvut.cz> + +Patch below adds support for using different prescaler than 16 for 16c950 +chips. This is needed for using Fujitsu-Siemens Connect2Air compact-flash +card, which comes (apparently) with 806kHz clocks, and so you have to +program prescaler for division by 7, and DLAB to 1, to get 115200Bd. + +To get card properly running you also have to add lines below to +/etc/pcmcia/serial.opts so kernel knows that base speed is not 115200 but +50400 (50400 * 16 = 806400; 806400 / 7 = 115200). As I've found no code +specifying baud_rate in serial_cs, I assume that specifying it in +serial.opts is right way to do this type of things. + +Patch also fixes problem that for UPF_MAGIC_MULTIPLIER maximum possible +baud rate passed to uart code was uartclk / 16 while correct value for +these devices (and for 16c950) is uartclk / 4. + +Patch also fixes problem that for UPF_MAGIC_MULTIPLIER devices with +baud_rate 19200 or 9600 spd_cust did not work correctly. Not that such +devices exist, but we should not ignore spd_cust, user probably knows why +he asked for spd_cust. + +serial.opts: + +case "$MANFID-$FUNCID-$PRODID_1-$PRODID_2-$PRODID_3-$PRODID_4" in +'0279,950b-2-GPRS Modem---') + SERIAL_OPTS="baud_base 50400" + ;; +esac + +Cc: David Woodhouse <dwmw2@infradead.org> +Signed-off-by: Andrew Morton <akpm@osdl.org> +--- + + drivers/serial/8250.c | 82 +++++++++++++++++++++++++++++++++++++++----------- + 1 file changed, 64 insertions(+), 18 deletions(-) + +Index: linux-2.6.21/drivers/serial/8250.c +=================================================================== +--- linux-2.6.21.orig/drivers/serial/8250.c 2007-07-01 16:59:52.000000000 +0100 ++++ linux-2.6.21/drivers/serial/8250.c 2007-07-01 17:01:21.000000000 +0100 +@@ -1964,24 +1964,58 @@ static void serial8250_shutdown(struct u + serial_unlink_irq_chain(up); + } + +-static unsigned int serial8250_get_divisor(struct uart_port *port, unsigned int baud) ++static unsigned int serial8250_get_divisor(struct uart_port *port, unsigned int baud, ++ unsigned int *prescaler) + { +- unsigned int quot; +- +- /* +- * Handle magic divisors for baud rates above baud_base on +- * SMSC SuperIO chips. ++ /* ++ * Use special handling only if user did not supply its own divider. ++ * spd_cust is defined in terms of baud_base, so always use default ++ * prescaler when spd_cust is requested. + */ +- if ((port->flags & UPF_MAGIC_MULTIPLIER) && +- baud == (port->uartclk/4)) +- quot = 0x8001; +- else if ((port->flags & UPF_MAGIC_MULTIPLIER) && +- baud == (port->uartclk/8)) +- quot = 0x8002; +- else +- quot = uart_get_divisor(port, baud); + +- return quot; ++ *prescaler = 16; ++ if (baud != 38400 || (port->flags & UPF_SPD_MASK) != UPF_SPD_CUST) { ++ unsigned int quot = port->uartclk / baud; ++ ++ /* ++ * Handle magic divisors for baud rates above baud_base on ++ * SMSC SuperIO chips. ++ */ ++ if (port->flags & UPF_MAGIC_MULTIPLIER) { ++ if (quot == 4) { ++ return 0x8001; ++ } else if (quot == 8) { ++ return 0x8002; ++ } ++ } ++ if (port->type == PORT_16C950) { ++ /* ++ * This computes TCR value (4 to 16), not CPR value (which can ++ * be between 1.000 and 31.875) - chip I have uses XTAL of ++ * 806400Hz, and so a division by 7 is required to get 115200Bd. ++ * I'm leaving CPR disabled for now, until someone will ++ * hit even more exotic XTAL (it is needed to get 500kbps ++ * or 1000kbps from 18.432MHz XTAL, but I have no device ++ * which would benefit from doing that). ++ * ++ * If we can use divide by 16, use it. Otherwise look for ++ * better prescaler, from 15 to 4. If quotient cannot ++ * be divided by any integer value between 4 and 15, use 4. ++ */ ++ if (quot & 0x0F) { ++ unsigned int div; ++ ++ for (div = 15; div > 4; div--) { ++ if (quot % div == 0) { ++ break; ++ } ++ } ++ *prescaler = div; ++ return quot / div; ++ } ++ } ++ } ++ return uart_get_divisor(port, baud); + } + + static void +@@ -1991,7 +2025,7 @@ serial8250_set_termios(struct uart_port + struct uart_8250_port *up = (struct uart_8250_port *)port; + unsigned char cval, fcr = 0; + unsigned long flags; +- unsigned int baud, quot; ++ unsigned int baud, quot, prescaler; + + switch (termios->c_cflag & CSIZE) { + case CS5: +@@ -2023,8 +2057,13 @@ serial8250_set_termios(struct uart_port + /* + * Ask the core to calculate the divisor for us. + */ +- baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk/16); +- quot = serial8250_get_divisor(port, baud); ++ if (port->type == PORT_16C950 || (port->flags & UPF_MAGIC_MULTIPLIER)) { ++ baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk/4); ++ } else { ++ baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk/16); ++ } ++ quot = serial8250_get_divisor(port, baud, &prescaler); ++ + + /* + * Oxford Semi 952 rev B workaround +@@ -2139,6 +2178,13 @@ serial8250_set_termios(struct uart_port + serial_dl_write(up, quot); + + /* ++ * Program prescaler for 16C950 chips. ++ */ ++ if (up->port.type == PORT_16C950) { ++ serial_icr_write(up, UART_TCR, prescaler == 16 ? 0 : prescaler); ++ } ++ ++ /* + * LCR DLAB must be set to enable 64-byte FIFO mode. If the FCR + * is written without DLAB set, this mode will be disabled. + */ |