target/linux/s3c24xx/patches-2.6.24/1087-introduce-fiq-hdq.patch.patch

   1 From ab6e925546e3d3361ab59c2b090eccf0cb411c7b Mon Sep 17 00:00:00 2001
   2 From: Andy Green <andy@openmoko.com>
   3 Date: Sun, 13 Apr 2008 07:25:48 +0100
   4 Subject: [PATCH] introduce-fiq-hdq.patch
   5
   6 This adds a platform driver and device which performs HDQ
   7 battery protocol using a single GPIO pin which is set
   8 through platform data.
   9
  10 HDQ has some hard latency requirements which can't
  11 be met if interrupts are enabled, so normally using
  12 a GPIO for this will require blocking out all other
  13 interrupts and processes for several milliseconds
  14 per register being read or written.
  15
  16 This HDQ protocol engine is a FSM implemented inside the
  17 the FIQ ISR and regulated by timer interrupts happening
  18 at 20us intervals.  The path through the FSM on any
  19 "clock" is very short and should be over with in ~
  20 1us.  Because FIQ has guaranteed latencies of <1us,
  21 it means we can service the HDQ protocol without
  22 blocking interrupts or any other process other than
  23 the caller that is waiting for the result. It's pretty
  24 cool performance from 1 GPIO ;-)
  25
  26 Due to it being hard to do locking from the FIQ ISR
  27 the code simply sleeps 10ms or whatever the scheduler
  28 gives it and checks if the transfer took place yet.
  29
  30 This platform driver doesn't have any knowledge about
  31 the device it is talking to, it just knows it is a
  32 HDQ device.  It exports three functions for read, write
  33 and confirming HDQ is initialized.  It also exports two
  34 /sys nodes that are usable by humans, one dumps the whole
  35 127 register HDQ register space
  36
  37 # cat /sys/devices/platform/gta02-hdq.0/hdq/dump
  38 00 44 55 00 00 00 ba 04 a2 0d 50 00 00 00 00 00
  39 00 00 9a 1a 00 00 ff ff ff ff 29 00 00 00 80 2b
  40 00 00 00 00 00 00 ff ff 00 00 00 00 00 32 af 06
  41 a0 d8 37 4e 00 00 00 00 00 00 00 34 2e 03 b4 e7
  42 00 00 06 00 41 00 4c 02 00 00 00 00 00 00 00 00
  43 83 02 00 00 94 09 59 b9 a5 0d 7f 21 00 00 7a ff
  44 df ff 62 ff a7 04 2e 05 00 00 00 01 00 07 00 00
  45 2a 78 36 67 7b b5 1b a9 af 19 38 89 63 57 42 7c
  46 #
  47
  48 and the other allows to set one register
  49
  50 # echo 2 170 > /sys/devices/platform/gta02-hdq.0/hdq/write
  51
  52 writes 0xAA into register 2.
  53
  54 Signed-off-by: Andy Green <andy@openmoko.com>
  55 ---
  56  defconfig-2.6.24      |    1 +
  57  drivers/power/Kconfig |    8 ++++++++
  58  2 files changed, 9 insertions(+), 0 deletions(-)
  59
  60 diff --git a/defconfig-2.6.24 b/defconfig-2.6.24
  61 index 833e15e..6d750a5 100644
  62 --- a/defconfig-2.6.24
  63 +++ b/defconfig-2.6.24
  64 @@ -1825,3 +1825,4 @@ CONFIG_TEXTSEARCH_FSM=m
  65  CONFIG_PLIST=y
  66  CONFIG_HAS_IOMEM=y
  67  CONFIG_HAS_DMA=y
  68 +CONFIG_GTA02_HDQ=y
  69 diff --git a/drivers/power/Kconfig b/drivers/power/Kconfig
  70 index feb8b0a..5ace872 100644
  71 --- a/drivers/power/Kconfig
  72 +++ b/drivers/power/Kconfig
  73 @@ -63,3 +63,11 @@ config GTA02_HDQ
  74           at least BATTERY_BQ27000_HDQ as well
  75
  76  endif # POWER_SUPPLY
  77 +
  78 +config GTA02_HDQ
  79 +       tristate "Neo Freerunner HDQ"
  80 +       depends on MACH_NEO1973_GTA02 && FIQ && S3C2440_C_FIQ
  81 +       help
  82 +         Say Y to enable support for communicating with an HDQ battery
  83 +         on the Neo Freerunner.  You probably want to select
  84 +         at least BATTERY_BQ27000_HDQ as well
  85 --
  86 1.5.6.5
  87