diff options
author | Linus Torvalds <torvalds@linux-foundation.org> | 2009-01-07 12:00:25 -0800 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-01-07 12:00:25 -0800 |
commit | 5bb47b9ff3d16d40f8d45380b373497a545fa280 (patch) | |
tree | e13dd34395473342dc75eff5cbaf5b1ea753631c /Documentation | |
parent | 2f2408a88cf8fa43febfd7fb5783e61b2937b0f9 (diff) | |
parent | 06af15e086e39a5a2a2413973a64af8e10122f28 (diff) |
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/cooloney/blackfin-2.6
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/cooloney/blackfin-2.6: (171 commits)
Blackfin arch: fix bug - BF527 0.2 silicon has different CPUID (DSPID) value
Blackfin arch: Enlarge flash partition for kenel for bf533/bf537 boards
Blackfin arch: fix bug: kernel crash when enable SDIO host driver
Blackfin arch: Print FP at level KERN_NOTICE
Blackfin arch: drop ad73311 test code
Blackfin arch: update board default configs
Blackfin arch: Set PB4 as the default irq for bf548 board v1.4+.
Blackfin arch: fix typo in early printk bit size processing
Blackfin arch: enable reprogram cclk and sclk for bf518f-ezbrd
Blackfin arch: add SDIO host driver platform data
Blackfin arch: fix bug - kernel stops at initial console
Blackfin arch: fix bug - kernel crash after config IP for ethernet port
Blackfin arch: add sdh support for bf518f-ezbrd
Blackfin arch: fix bug - kernel detects BF532 incorrectly
Blackfin arch: add () to avoid warnings from gcc
Blackfin arch: change HWTRACE Kconfig and set it on default
Blackfin arch: Clean oprofile build path for blackfin
Blackfin arch: remove hardware PM code, oprofile not use it
Blackfin arch: rewrite get_sclk()/get_vco()
Blackfin arch: cleanup and unify the ins functions
...
Diffstat (limited to 'Documentation')
-rw-r--r-- | Documentation/blackfin/00-INDEX | 3 | ||||
-rw-r--r-- | Documentation/blackfin/bfin-gpio-notes.txt | 71 |
2 files changed, 74 insertions, 0 deletions
diff --git a/Documentation/blackfin/00-INDEX b/Documentation/blackfin/00-INDEX index 7cb3b356b24..d6840a91e1e 100644 --- a/Documentation/blackfin/00-INDEX +++ b/Documentation/blackfin/00-INDEX @@ -9,3 +9,6 @@ cachefeatures.txt Filesystems - Requirements for mounting the root file system. + +bfin-gpio-note.txt + - Notes in developing/using bfin-gpio driver. diff --git a/Documentation/blackfin/bfin-gpio-notes.txt b/Documentation/blackfin/bfin-gpio-notes.txt new file mode 100644 index 00000000000..9898c7ded7d --- /dev/null +++ b/Documentation/blackfin/bfin-gpio-notes.txt @@ -0,0 +1,71 @@ +/* + * File: Documentation/blackfin/bfin-gpio-note.txt + * Based on: + * Author: + * + * Created: $Id: bfin-gpio-note.txt 2008-11-24 16:42 grafyang $ + * Description: This file contains the notes in developing/using bfin-gpio. + * + * + * Rev: + * + * Modified: + * Copyright 2004-2008 Analog Devices Inc. + * + * Bugs: Enter bugs at http://blackfin.uclinux.org/ + * + */ + + +1. Blackfin GPIO introduction + + There are many GPIO pins on Blackfin. Most of these pins are muxed to + multi-functions. They can be configured as peripheral, or just as GPIO, + configured to input with interrupt enabled, or output. + + For detailed information, please see "arch/blackfin/kernel/bfin_gpio.c", + or the relevant HRM. + + +2. Avoiding resource conflict + + Followed function groups are used to avoiding resource conflict, + - Use the pin as peripheral, + int peripheral_request(unsigned short per, const char *label); + int peripheral_request_list(const unsigned short per[], const char *label); + void peripheral_free(unsigned short per); + void peripheral_free_list(const unsigned short per[]); + - Use the pin as GPIO, + int bfin_gpio_request(unsigned gpio, const char *label); + void bfin_gpio_free(unsigned gpio); + - Use the pin as GPIO interrupt, + int bfin_gpio_irq_request(unsigned gpio, const char *label); + void bfin_gpio_irq_free(unsigned gpio); + + The request functions will record the function state for a certain pin, + the free functions will clear it's function state. + Once a pin is requested, it can't be requested again before it is freed by + previous caller, otherwise kernel will dump stacks, and the request + function fail. + These functions are wrapped by other functions, most of the users need not + care. + + +3. But there are some exceptions + - Kernel permit the identical GPIO be requested both as GPIO and GPIO + interrut. + Some drivers, like gpio-keys, need this behavior. Kernel only print out + warning messages like, + bfin-gpio: GPIO 24 is already reserved by gpio-keys: BTN0, and you are +configuring it as IRQ! + + Note: Consider the case that, if there are two drivers need the + identical GPIO, one of them use it as GPIO, the other use it as + GPIO interrupt. This will really cause resource conflict. So if + there is any abnormal driver behavior, please check the bfin-gpio + warning messages. + + - Kernel permit the identical GPIO be requested from the same driver twice. + + + |