[U-Boot] [PATCH 12/14] dm: Add pcmcia design document

Marek Vasut
2012-08-08T11:42:28Z

From: Viktor Krivak <viktor.krivak@gmail.com>

Signed-off-by: Viktor Krivak <viktor.krivak@gmail.com>
---
doc/driver-model/UDM-pcmcia.txt | 79 +++++++++++++++++++++++++++++++++++++++
1 file changed, 79 insertions(+)
create mode 100644 doc/driver-model/UDM-pcmcia.txt

diff --git a/doc/driver-model/UDM-pcmcia.txt b/doc/driver-model/UDM-pcmcia.txt
new file mode 100644
index 0000000..6ee0168
--- /dev/null
+++ b/doc/driver-model/UDM-pcmcia.txt
@@ -0,0 +1,79 @@
+The U-Boot Driver Model Project
+===============================
+PCMCIA analysis
+===============
+Viktor Krivak <viktor.krivak@gmail.com>
+2012-03-17
+
+I) Overview
+-----------
+
+ U-boot implements only 2 methods to interoperate with pcmcia. One to turn
+ device on and other to turn device off. Names of these methods are usually
+ pcmcia_on() and pcmcia_off() without any parameters. Some files in driver
+ directory implements only internal API. These methods aren't used outside
+ driver directory and they are not converted to new driver model.
+
+II) Approach
+-----------
+
+ 1) New API
+ ----------
+
+ Current API is preserved and all internal methods are hiden.
+
+ struct ops {
+ void (*pcmcia_on)(struct instance *i);
+ void (*pcmcia_off)(struct instance *i);
+ }
+
+ 2) Conversion
+ -------------
+
+ In header file pcmcia.h are some other variables which are used for
+ additional configuration. But all have to be moved to platform data or to
+ specific driver implementation.
+
+ 3) Platform data
+ ----------------
+
+ Many boards have custom implementation of internal API. Pointers to these
+ methods are stored in platform_data. But the most implementations for Intel
+ 82365 and compatible PC Card controllers and Yenta-compatible
+ PCI-to-CardBus controllers implement whole API per board. In these cases
+ pcmcia_on() and pcmcia_off() behave only as wrappers and call specific
+ board methods.
+
+III) Analysis of in-tree drivers
+--------------------------------
+
+ 1) i82365.c
+ -----------
+ Driver methods have different name i82365_init() and i82365_exit but
+ all functionality is the same. Board files board/atc/ti113x.c and
+ board/cpc45/pd67290.c use their own implementation of these method.
+ In this case all methods in driver behave only as wrappers.
+
+ 2) marubun_pcmcia.c
+ -------------------
+ Meets standard API behaviour. Simple conversion.
+
+ 3) mpc8xx_pcmcia.c
+ ------------------
+ Meets standard API behaviour. Simple conversion.
+
+ 4) rpx_pcmcia.c
+ ---------------
+ Implements only internal API used in other drivers. Non of methods
+ implemented here are used outside driver model.
+
+ 5) ti_pci1410a.c
+ ----------------
+ Has different API but methods in this file are never called. Probably
+ dead code.
+
+ 6)tqm8xx_pcmcia.c
+ -----------------
+ Implements only internal API used in other drivers. Non of methods
+ implemented here are used outside driver model.
+
--
1.7.10.4