In addition to the /32 prescaler, the MPC5200B supports a second
baudrate prescaler /4 to reach higher baudrates.
The current calculation (introduced with commit 0d1f22e4) in the kernel
preferes this low prescaler as often as possible, but with some
imprecise counterparts the communication on low baudrates fails.
According a support-mail from freescale the low prescaler (/4) allows
just 1% tolerance in bittiming in contrast to 4% of the high prescaler
(/32). The prescaler not only affects the baudrate-calculation, but
also the sampling of the bits on the wire.
With this patch, we use the slightly less precise, but higher tolerant
prescaler calculation on low baudrates up to (and including) 115200 baud
and the more precise calculation above.
Tested on a custom MPC5200B board with "fsl,mpc5200b-psc-uart".
Calculation Examples with prescaler (PS) 4 and 32 and divisor (DIV) on
various baudrates. Real stands for the real baudrate generated and Diff
for the differences between:
50 Baud PS 32 DIV 0xa122 Real 50 Diff 0.00%
75 Baud PS 32 DIV 0x6b6c Real 75 Diff 0.00%
110 Baud PS 32 DIV 0x493e Real 110 Diff 0.00%
134 Baud PS 32 DIV 0x3c20 Real 133 Diff 0.75%
150 Baud PS 32 DIV 0x35b6 Real 150 Diff 0.00%
200 Baud PS 32 DIV 0x2849 Real 199 Diff 0.50%
300 Baud PS 4 DIV 0xd6d8 Real 300 Diff 0.00%
PS 32 DIV 0x1adb Real 300 Diff 0.00%
600 Baud PS 4 DIV 0x6b6c Real 600 Diff 0.00%
PS 32 DIV 0x0d6e Real 599 Diff 0.17%
1200 Baud PS 4 DIV 0x35b6 Real 1200 Diff 0.00%
PS 32 DIV 0x06b7 Real 1199 Diff 0.08%
1800 Baud PS 4 DIV 0x23cf Real 1799 Diff 0.06%
PS 32 DIV 0x047a Real 1799 Diff 0.06%
2400 Baud PS 4 DIV 0x1adb Real 2400 Diff 0.00%
PS 32 DIV 0x035b Real 2401 Diff - 0.04%
4800 Baud PS 4 DIV 0x0d6e Real 4799 Diff 0.02%
PS 32 DIV 0x01ae Real 4796 Diff 0.08%
9600 Baud PS 4 DIV 0x06b7 Real 9598 Diff 0.02%
PS 32 DIV 0x00d7 Real 9593 Diff 0.07%
19200 Baud PS 4 DIV 0x035b Real 19208 Diff - 0.04%
PS 32 DIV 0x006b Real 19275 Diff - 0.39%
38400 Baud PS 4 DIV 0x01ae Real 38372 Diff 0.07%
PS 32 DIV 0x0036 Real 38194 Diff 0.54%
57600 Baud PS 4 DIV 0x011e Real 57692 Diff - 0.16%
PS 32 DIV 0x0024 Real 57291 Diff 0.54%
76800 Baud PS 4 DIV 0x00d7 Real 76744 Diff 0.07%
PS 32 DIV 0x001b Real 76388 Diff 0.54%
115200 Baud PS 4 DIV 0x008f Real 115384 Diff - 0.16%
PS 32 DIV 0x0012 Real 114583 Diff 0.54%
153600 Baud PS 4 DIV 0x006b Real 154205 Diff - 0.39%
PS 32 DIV 0x000d Real 158653 Diff - 3.29%
230400 Baud PS 4 DIV 0x0048 Real 229166 Diff 0.54%
PS 32 DIV 0x0009 Real 229166 Diff 0.54%
307200 Baud PS 4 DIV 0x0036 Real 305555 Diff 0.54%
PS 32 DIV 0x0007 Real 294642 Diff 4.09%
460800 Baud PS 4 DIV 0x0024 Real 458333 Diff 0.54%
PS 32 DIV 0x0005 Real 412500 Diff 10.48%
500000 Baud PS 4 DIV 0x0021 Real 500000 Diff 0.00%
PS 32 DIV 0x0004 Real 515625 Diff - 3.13%
576000 Baud PS 4 DIV 0x001d Real 568965 Diff 1.22%
PS 32 DIV 0x0004 Real 515625 Diff 10.48%
614400 Baud PS 4 DIV 0x001b Real 611111 Diff 0.54%
PS 32 DIV 0x0003 Real 687500 Diff -11.90%
921600 Baud PS 4 DIV 0x0012 Real 916666 Diff 0.54%
PS 32 DIV 0x0002 Real 1031250 Diff -11.90%
1000000 Baud PS 4 DIV 0x0011 Real 970588 Diff 2.94%
PS 32 DIV 0x0002 Real 1031250 Diff - 3.13%
1152000 Baud PS 4 DIV 0x000e Real 1178571 Diff - 2.31%
PS 32 DIV 0x0002 Real 1031250 Diff 10.48%
1500000 Baud PS 4 DIV 0x000b Real 1500000 Diff 0.00%
PS 32 DIV 0x0001 Real 2062500 Diff -37.50%
2000000 Baud PS 4 DIV 0x0008 Real 2062500 Diff - 3.13%
PS 32 DIV 0x0001 Real 2062500 Diff - 3.13%
2500000 Baud PS 4 DIV 0x0007 Real 2357142 Diff 5.71%
PS 32 DIV 0x0001 Real 2062500 Diff 17.50%
3000000 Baud PS 4 DIV 0x0006 Real 2750000 Diff 8.33%
PS 32 DIV 0x0001 Real 2062500 Diff 31.25%
3500000 Baud PS 4 DIV 0x0005 Real 3300000 Diff 5.71%
PS 32 DIV 0x0001 Real 2062500 Diff 41.07%
4000000 Baud PS 4 DIV 0x0004 Real 4125000 Diff - 3.13%
PS 32 DIV 0x0001 Real 2062500 Diff 48.44%
Signed-off-by: Frank Benkert <frank.benkert@avat.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
We transform the offenders into a test of irq <= 0 which will be ok while
the ARM people get their platform sorted. Once that is done (or in a while
if they don't do it anyway) then we will change them all to !irq checks.
For arch specific drivers that are already using NO_IRQ = 0 we just test
against zero so we don't need to re-review them later.
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Since commit [e58aa3d2: genirq: Run irq handlers with interrupts disabled],
We run all interrupt handlers with interrupts disabled
and we even check and yell when an interrupt handler
returns with interrupts enabled (see commit [b738a50a:
genirq: Warn when handler enables interrupts]).
So now this flag is a NOOP and can be removed.
Signed-off-by: Yong Zhang <yong.zhang0@gmail.com>
Acked-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
linux/tty_flip.h is included in linux/serial_core.h. But this may (and
will) change in the future. Then we would get build errors such as:
.../tty/serial/max3107.c: In function ‘put_data_to_circ_buf’:
.../tty/serial/max3107.c:149:2: error: implicit declaration of function ‘tty_insert_flip_string’
So fix all the drviers which call tty flip buffer helpers to really
include linux/tty_flip.h. And also make sure that those include
linux/tty.h when operating with struct tty_struct.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Get rid of users of of_platform_driver in drivers/serial. The
of_platform_{,un}register_driver functions are going away, so the
users need to be converted to using the platform_bus_type directly.
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
The serial drivers are really just tty drivers, so move them to
drivers/tty/ to make things a bit neater overall.
This is part of the tty/serial driver movement proceedure as proposed by
Arnd Bergmann and approved by everyone involved a number of months ago.
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Rogier Wolff <R.E.Wolff@bitwizard.nl>
Cc: Michael H. Warfield <mhw@wittsend.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2011-01-13 12:10:18 -08:00
Renamed from drivers/serial/mpc52xx_uart.c (Browse further)
