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Doug Anderson 178624403c watchdog: s3c2410_wdt: Handle rounding a little better for timeout 
The existing watchdog timeout worked OK but didn't deal with
rounding in an ideal way when dividing out all of its clocks.

Specifically if you had a timeout of 32 seconds and an input clock of
66666666, you'd end up setting a timeout of 31.9998 seconds and
reporting a timeout of 31 seconds.

Specifically DBG printouts showed:
  s3c2410wdt_set_heartbeat: count=16666656, timeout=32, freq=520833
  s3c2410wdt_set_heartbeat: timeout=32, divisor=255, count=16666656 (0000ff4f)
and the final timeout reported to the user was:
  ((count / divisor) * divisor) / freq
  (0xff4f * 255) / 520833 = 31 (truncated from 31.9998)
the technically "correct" value is:
  (0xff4f * 255) / (66666666.0 / 128) = 31.9998

By using "DIV_ROUND_UP" we can be a little more correct.
  s3c2410wdt_set_heartbeat: count=16666688, timeout=32, freq=520834
  s3c2410wdt_set_heartbeat: timeout=32, divisor=255, count=16666688 (0000ff50)
and the final timeout reported to the user:
  (0xff50 * 255) / 520834 = 32
the technically "correct" value is:
  (0xff50 * 255) / (66666666.0 / 128) = 32.0003

We'll use a DIV_ROUND_UP to solve this, generally erroring on the side
of reporting shorter values to the user and setting the watchdog to
slightly longer than requested:
* Round input frequency up to assume watchdog is counting faster.
* Round divisions by divisor up to give us extra time.

At the same time we can avoid a for loop by just doing the right math.

Signed-off-by: Doug Anderson <dianders@chromium.org>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
 		2014-01-28 21:23:20 +01:00
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accessibility
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acpi ACPI and power management updates for 3.14-rc1 2014-01-24 15:51:02 -08:00
amba
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ata ACPI and power management updates for 3.14-rc1 2014-01-24 15:51:02 -08:00
atm
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auxdisplay
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base regmap: Updates for v3.14 2014-01-25 13:18:00 -08:00
bcma Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/linville/wireless-next into for-davem 2014-01-10 10:59:40 -05:00
block drivers/block/Kconfig: update RAM block device module name 2014-01-23 16:36:53 -08:00
bluetooth Merge branch 'for-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth-next 2014-01-08 13:44:29 -05:00
bus
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cdrom
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char Merge branch 'ipmi' (ipmi patches from Corey Minyard) 2014-01-25 15:33:41 -08:00
clk The first half of the clk framework pull request is made up almost 2014-01-23 18:56:08 -08:00
clocksource ARM: SoC DT updates for 3.14 2014-01-23 18:45:38 -08:00
connector
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cpufreq Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/rzhang/linux 2014-01-24 17:13:49 -08:00
cpuidle
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crypto ARM: driver updates for 3.14 2014-01-23 18:49:36 -08:00
dca
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devfreq ARM: SoC cleanups for 3.14 2014-01-23 18:36:55 -08:00
dio
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dma ARM: SoC DT updates for 3.14 2014-01-23 18:45:38 -08:00
edac Merge branch 'x86-ras-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-01-20 12:10:27 -08:00
eisa Revert "EISA: Initialize device before its resources" 2014-01-17 14:57:29 -07:00
extcon extcon: gpio: Add power resume support 2014-01-09 09:53:30 +09:00
firewire firewire: Enable remote DMA above 4 GB 2014-01-20 01:11:13 +01:00
firmware firmware/google: drop 'select EFI' to avoid recursive dependency 2014-01-27 21:02:40 -08:00
fmc
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gpio ARM: driver updates for 3.14 2014-01-23 18:49:36 -08:00
gpu ACPI and power management updates for 3.14-rc1 2014-01-24 15:51:02 -08:00
hid ACPI and power management updates for 3.14-rc1 2014-01-24 15:51:02 -08:00
hsi
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hv ACPI and power management updates for 3.14-rc1 2014-01-24 15:51:02 -08:00
hwmon Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/rzhang/linux 2014-01-24 17:13:49 -08:00
hwspinlock
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i2c ACPI and power management updates for 3.14-rc1 2014-01-24 15:51:02 -08:00
ide ACPI and power management updates for 3.14-rc1 2014-01-24 15:51:02 -08:00
idle ACPI and power management updates for 3.14-rc1 2014-01-24 15:51:02 -08:00
iio Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2014-01-22 21:21:55 -08:00
infiniband Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2014-01-25 11:17:34 -08:00
input Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input 2014-01-24 17:17:30 -08:00
iommu ACPI and power management updates for 3.14-rc1 2014-01-24 15:51:02 -08:00
ipack
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irqchip Xtensa patchset for 3.14-rc1 2014-01-25 10:49:30 -08:00
isdn Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2014-01-25 11:17:34 -08:00
leds Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2014-01-22 21:21:55 -08:00
lguest
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macintosh Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc 2014-01-27 21:11:26 -08:00
mailbox drivers/mailbox/omap: make mbox->irq signed for error handling 2014-01-23 16:36:53 -08:00
md md updates for 3.14 2014-01-24 17:41:50 -08:00
media Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2014-01-25 11:17:34 -08:00
memory
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memstick drivers/memstick/host/rtsx_pci_ms.c: fix ms card data transfer bug 2014-01-23 16:37:04 -08:00
message MPT / PCI: Use pci_stop_and_remove_bus_device_locked() 2014-01-14 12:14:25 -07:00
mfd regulator: Updates for v3.14 2014-01-25 13:19:10 -08:00
misc Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2014-01-22 21:21:55 -08:00
mmc MMC highlights for 3.14: 2014-01-26 11:00:41 -08:00
mtd Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2014-01-22 21:21:55 -08:00
net Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc 2014-01-27 21:11:26 -08:00
nfc NFC: nfcmrvl: Fix possible memory leak issue 2014-01-09 01:27:20 +01:00
ntb
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nubus
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of Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2014-01-25 11:17:34 -08:00
oprofile
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parisc
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parport TTY/Serial driver patches for 3.14-rc1 2014-01-20 16:05:23 -08:00
pci ACPI and power management updates for 3.14-rc1 2014-01-24 15:51:02 -08:00
pcmcia PCI changes for the v3.14 merge window: 2014-01-22 16:39:28 -08:00
phy Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2014-01-25 11:17:34 -08:00
pinctrl ARM: SoC DT updates for 3.14 2014-01-23 18:45:38 -08:00
platform ACPI and power management updates for 3.14-rc1 2014-01-24 15:51:02 -08:00
pnp Merge branch 'pnp' 2014-01-12 23:48:18 +01:00
power Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2014-01-25 11:17:34 -08:00
powercap
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pps
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ps3
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ptp ptp_pch: Add dependency on HAS_IOMEM 2014-01-15 14:51:22 -08:00
pwm pwm: Changes for v3.14-rc1 2014-01-27 08:15:51 -08:00
rapidio
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regulator regulator: Updates for v3.14 2014-01-25 13:19:10 -08:00
remoteproc
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reset
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rpmsg
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rtc Merge branch 'akpm' (incoming from Andrew) 2014-01-23 19:11:50 -08:00
s390 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux 2014-01-28 09:02:24 -08:00
sbus
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scsi Main batch of InfiniBand/RDMA changes for 3.14: 2014-01-24 17:18:32 -08:00
sfi
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sh
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sn
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spi spi: Updates for v3.14 2014-01-25 13:20:36 -08:00
ssb
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staging Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2014-01-25 11:17:34 -08:00
target
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tc
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thermal Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/rzhang/linux 2014-01-24 17:13:49 -08:00
tty Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux 2014-01-28 09:02:24 -08:00
uio
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usb ACPI and power management updates for 3.14-rc1 2014-01-24 15:51:02 -08:00
uwb
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vfio Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc 2014-01-27 21:11:26 -08:00
vhost
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video pwm: Changes for v3.14-rc1 2014-01-27 08:15:51 -08:00
virt
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virtio A few simple fixes. Quiet cycle. 2014-01-22 22:24:35 -08:00
vlynq drivers/vlynq/vlynq.c: fix another resource size off by 1 error 2014-01-23 16:36:55 -08:00
vme
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w1 drivers/w1/masters/w1-gpio.c: add strong pullup emulation 2014-01-23 16:37:04 -08:00
watchdog watchdog: s3c2410_wdt: Handle rounding a little better for timeout 2014-01-28 21:23:20 +01:00
xen ACPI and power management updates for 3.14-rc1 2014-01-24 15:51:02 -08:00
zorro
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Kconfig
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Makefile
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