From 46f0b99a7b0e52e8dee4cdfe2e3599814f0388ed Mon Sep 17 00:00:00 2001 From: Andy Green Date: Fri, 25 Jul 2008 23:06:00 +0100 Subject: [PATCH] introduce-fiq-hdq.patch This adds a platform driver and device which performs HDQ battery protocol using a single GPIO pin which is set through platform data. HDQ has some hard latency requirements which can't be met if interrupts are enabled, so normally using a GPIO for this will require blocking out all other interrupts and processes for several milliseconds per register being read or written. This HDQ protocol engine is a FSM implemented inside the the FIQ ISR and regulated by timer interrupts happening at 20us intervals. The path through the FSM on any "clock" is very short and should be over with in ~ 1us. Because FIQ has guaranteed latencies of <1us, it means we can service the HDQ protocol without blocking interrupts or any other process other than the caller that is waiting for the result. It's pretty cool performance from 1 GPIO ;-) Due to it being hard to do locking from the FIQ ISR the code simply sleeps 10ms or whatever the scheduler gives it and checks if the transfer took place yet. This platform driver doesn't have any knowledge about the device it is talking to, it just knows it is a HDQ device. It exports three functions for read, write and confirming HDQ is initialized. It also exports two /sys nodes that are usable by humans, one dumps the whole 127 register HDQ register space # cat /sys/devices/platform/gta02-hdq.0/hdq/dump 00 44 55 00 00 00 ba 04 a2 0d 50 00 00 00 00 00 00 00 9a 1a 00 00 ff ff ff ff 29 00 00 00 80 2b 00 00 00 00 00 00 ff ff 00 00 00 00 00 32 af 06 a0 d8 37 4e 00 00 00 00 00 00 00 34 2e 03 b4 e7 00 00 06 00 41 00 4c 02 00 00 00 00 00 00 00 00 83 02 00 00 94 09 59 b9 a5 0d 7f 21 00 00 7a ff df ff 62 ff a7 04 2e 05 00 00 00 01 00 07 00 00 2a 78 36 67 7b b5 1b a9 af 19 38 89 63 57 42 7c # and the other allows to set one register # echo 2 170 > /sys/devices/platform/gta02-hdq.0/hdq/write writes 0xAA into register 2. Signed-off-by: Andy Green --- defconfig-2.6.24 | 1 + drivers/power/Kconfig | 8 ++++++++ 2 files changed, 9 insertions(+), 0 deletions(-) diff --git a/defconfig-2.6.24 b/defconfig-2.6.24 index 833e15e..6d750a5 100644 --- a/defconfig-2.6.24 +++ b/defconfig-2.6.24 @@ -1825,3 +1825,4 @@ CONFIG_TEXTSEARCH_FSM=m CONFIG_PLIST=y CONFIG_HAS_IOMEM=y CONFIG_HAS_DMA=y +CONFIG_GTA02_HDQ=y diff --git a/drivers/power/Kconfig b/drivers/power/Kconfig index feb8b0a..5ace872 100644 --- a/drivers/power/Kconfig +++ b/drivers/power/Kconfig @@ -63,3 +63,11 @@ config GTA02_HDQ at least BATTERY_BQ27000_HDQ as well endif # POWER_SUPPLY + +config GTA02_HDQ + tristate "Neo Freerunner HDQ" + depends on MACH_NEO1973_GTA02 && FIQ && S3C2440_C_FIQ + help + Say Y to enable support for communicating with an HDQ battery + on the Neo Freerunner. You probably want to select + at least BATTERY_BQ27000_HDQ as well -- 1.5.6.3