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