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authorLinus Torvalds <torvalds@linux-foundation.org>2009-01-07 15:00:25 -0500
committerLinus Torvalds <torvalds@linux-foundation.org>2009-01-07 15:00:25 -0500
commit5bb47b9ff3d16d40f8d45380b373497a545fa280 (patch)
treee13dd34395473342dc75eff5cbaf5b1ea753631c /Documentation
parent2f2408a88cf8fa43febfd7fb5783e61b2937b0f9 (diff)
parent06af15e086e39a5a2a2413973a64af8e10122f28 (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-INDEX3
-rw-r--r--Documentation/blackfin/bfin-gpio-notes.txt71
2 files changed, 74 insertions, 0 deletions
diff --git a/Documentation/blackfin/00-INDEX b/Documentation/blackfin/00-INDEX
index 7cb3b356b249..d6840a91e1e1 100644
--- a/Documentation/blackfin/00-INDEX
+++ b/Documentation/blackfin/00-INDEX
@@ -9,3 +9,6 @@ cachefeatures.txt
9 9
10Filesystems 10Filesystems
11 - Requirements for mounting the root file system. 11 - Requirements for mounting the root file system.
12
13bfin-gpio-note.txt
14 - 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 000000000000..9898c7ded7d3
--- /dev/null
+++ b/Documentation/blackfin/bfin-gpio-notes.txt
@@ -0,0 +1,71 @@
1/*
2 * File: Documentation/blackfin/bfin-gpio-note.txt
3 * Based on:
4 * Author:
5 *
6 * Created: $Id: bfin-gpio-note.txt 2008-11-24 16:42 grafyang $
7 * Description: This file contains the notes in developing/using bfin-gpio.
8 *
9 *
10 * Rev:
11 *
12 * Modified:
13 * Copyright 2004-2008 Analog Devices Inc.
14 *
15 * Bugs: Enter bugs at http://blackfin.uclinux.org/
16 *
17 */
18
19
201. Blackfin GPIO introduction
21
22 There are many GPIO pins on Blackfin. Most of these pins are muxed to
23 multi-functions. They can be configured as peripheral, or just as GPIO,
24 configured to input with interrupt enabled, or output.
25
26 For detailed information, please see "arch/blackfin/kernel/bfin_gpio.c",
27 or the relevant HRM.
28
29
302. Avoiding resource conflict
31
32 Followed function groups are used to avoiding resource conflict,
33 - Use the pin as peripheral,
34 int peripheral_request(unsigned short per, const char *label);
35 int peripheral_request_list(const unsigned short per[], const char *label);
36 void peripheral_free(unsigned short per);
37 void peripheral_free_list(const unsigned short per[]);
38 - Use the pin as GPIO,
39 int bfin_gpio_request(unsigned gpio, const char *label);
40 void bfin_gpio_free(unsigned gpio);
41 - Use the pin as GPIO interrupt,
42 int bfin_gpio_irq_request(unsigned gpio, const char *label);
43 void bfin_gpio_irq_free(unsigned gpio);
44
45 The request functions will record the function state for a certain pin,
46 the free functions will clear it's function state.
47 Once a pin is requested, it can't be requested again before it is freed by
48 previous caller, otherwise kernel will dump stacks, and the request
49 function fail.
50 These functions are wrapped by other functions, most of the users need not
51 care.
52
53
543. But there are some exceptions
55 - Kernel permit the identical GPIO be requested both as GPIO and GPIO
56 interrut.
57 Some drivers, like gpio-keys, need this behavior. Kernel only print out
58 warning messages like,
59 bfin-gpio: GPIO 24 is already reserved by gpio-keys: BTN0, and you are
60configuring it as IRQ!
61
62 Note: Consider the case that, if there are two drivers need the
63 identical GPIO, one of them use it as GPIO, the other use it as
64 GPIO interrupt. This will really cause resource conflict. So if
65 there is any abnormal driver behavior, please check the bfin-gpio
66 warning messages.
67
68 - Kernel permit the identical GPIO be requested from the same driver twice.
69
70
71