mirror of
https://github.com/AsahiLinux/u-boot
synced 2024-11-10 23:24:38 +00:00
dm: add PCI design document
Signed-off-by: Pavel Herrmann <morpheus.ibis@gmail.com>
This commit is contained in:
parent
f07563a7a5
commit
a09c649972
1 changed files with 265 additions and 0 deletions
265
doc/driver-model/UDM-pci.txt
Normal file
265
doc/driver-model/UDM-pci.txt
Normal file
|
@ -0,0 +1,265 @@
|
|||
The U-Boot Driver Model Project
|
||||
===============================
|
||||
PCI subsystem analysis
|
||||
======================
|
||||
|
||||
Pavel Herrmann <morpheus.ibis@gmail.com>
|
||||
2012-03-17
|
||||
|
||||
I) Overview
|
||||
-----------
|
||||
|
||||
U-Boot already supports multiple PCI busses, stored in a linked-list of
|
||||
pci_controller structures. This structure contains generic driver data, bus
|
||||
interface operations and private data for the driver.
|
||||
|
||||
Bus interface operations for PCI are (names are self-explanatory):
|
||||
|
||||
read_byte()
|
||||
read_word()
|
||||
read_dword()
|
||||
write_byte()
|
||||
write_word()
|
||||
write_dword()
|
||||
|
||||
Each driver has to implement dword operations, and either implement word and
|
||||
byte operations, or use shared $operation_config_$type_via_dword (eg.
|
||||
read_config_byte_via_dword and similar) function. These functions are used
|
||||
for config space I/O (read_config_dword and similar functions of the PCI
|
||||
subsystem), which is used to configure the connected devices for standard MMIO
|
||||
operations. All data transfers by respective device drivers are then done by
|
||||
MMIO
|
||||
|
||||
Each driver also defines a separate init function, which has unique symbol
|
||||
name, and thus more drivers can be compiled in without colliding. This init
|
||||
function is typically called from pci_init_board(), different for each
|
||||
particular board.
|
||||
|
||||
Some boards also define a function called fixup_irq, which gets called after
|
||||
scanning the PCI bus for devices, and should dismiss any interrupts.
|
||||
|
||||
Several drivers are also located in arch/ and should be moved to drivers/pci.
|
||||
|
||||
II) Approach
|
||||
------------
|
||||
|
||||
The pci_controller structure needs to be broken down to fit the new driver
|
||||
model. Due to a large number of members, this will be done through three
|
||||
distinct accessors, one for memory regions, one for config table and one for
|
||||
everything else. That will make the pci_ops structure look like this:
|
||||
|
||||
struct pci_ops {
|
||||
int (*read_byte)(struct instance *bus, pci_dev_t *dev, int addr,
|
||||
u8 *buf);
|
||||
int (*read_word)(struct instance *bus, pci_dev_t *dev, int addr,
|
||||
u16 *buf);
|
||||
int (*read_dword)(struct instance *bus, pci_dev_t *dev, int addr,
|
||||
u32 *buf);
|
||||
int (*write_byte)(struct instance *bus, pci_dev_t *dev, int addr,
|
||||
u8 val);
|
||||
int (*write_byte)(struct instance *bus, pci_dev_t *dev, int addr,
|
||||
u8 val);
|
||||
int (*write_dword)(struct instance *bus, pci_dev_t *dev, int addr,
|
||||
u32 val);
|
||||
void (*fixup_irq)(struct instance *bus, pci_dev_t *dev);
|
||||
struct pci_region* (*get_region)(struct instance *, uint num);
|
||||
struct pci_config_table* (*get_cfg_table)(struct instance *bus);
|
||||
uint (*get_option)(struct instance * bus, enum pci_option_code op);
|
||||
}
|
||||
|
||||
enum pci_option_code {
|
||||
PCI_OPT_BUS_NUMBER=0,
|
||||
PCI_OPT_REGION_COUNT,
|
||||
PCI_OPT_INDIRECT_TYPE,
|
||||
PCI_OPT_AUTO_MEM,
|
||||
PCI_OPT_AUTO_IO,
|
||||
PCI_OPT_AUTO_PREFETCH,
|
||||
PCI_OPT_AUTO_FB,
|
||||
PCI_OPT_CURRENT_BUS,
|
||||
PCI_OPT_CFG_ADDR,
|
||||
}
|
||||
|
||||
The return value for get_option will be an unsigned integer value for any
|
||||
option code. If the option currently is a pointer to pci_region, it will
|
||||
return an index for get_region function. Special case has to be made for
|
||||
PCI_OPT_CFG_ADDR, which should be interpreted as a pointer, but it is only
|
||||
used for equality in find_hose_by_cfg_addr, and thus can be returned as an
|
||||
uint. Other function using cfg_addr value are read/write functions for
|
||||
specific drivers (especially ops for indirect bridges), and thus have access
|
||||
to private_data of the driver instance.
|
||||
|
||||
The config table accessor will return a pointer to a NULL-terminated array of
|
||||
pci_config_table, which is supplied by the board in platform_data, or NULL if
|
||||
the board didn't specify one. This table is used to override PnP
|
||||
auto-initialization, or to specific initialization functions for non-PNP
|
||||
devices.
|
||||
|
||||
Transparent PCI-PCI bridges will get their own driver, and will forward all
|
||||
operations to operations of their parent bus. This however makes it
|
||||
impossible to use instances to identify devices, as not all devices will be
|
||||
directly visible to the respective bus driver.
|
||||
|
||||
Init functions of controller drivers will be moved to their respective
|
||||
probe() functions, in accordance to the driver model.
|
||||
|
||||
The PCI core will handle all mapping functions currently found in pci.c, as
|
||||
well as proxy functions for read/write operations of the drivers. The PCI
|
||||
core will also handle bus scanning and device configuration.
|
||||
|
||||
The PnP helper functions currently in pci_auto.c will also be a part of PCI
|
||||
core, but they will be exposed only to PCI controller drivers, not to other
|
||||
device drivers.
|
||||
|
||||
The PCI API for device drivers will remain largely unchanged, most drivers
|
||||
will require no changes at all, and all modifications will be limited to
|
||||
changing the pci_controlle into instance*.
|
||||
|
||||
III) Analysis of in-tree drivers
|
||||
--------------------------------
|
||||
|
||||
A) drivers in drivers/pci/
|
||||
--------------------------
|
||||
|
||||
1) pci_indirect.c
|
||||
-----------------
|
||||
Shared driver for indirect PCI bridges, several CONFIG macros - will
|
||||
require significant cleanup.
|
||||
|
||||
2) pci_ixp.c
|
||||
------------
|
||||
Standard driver, specifies all read/write functions separately.
|
||||
|
||||
3) pci_sh4.c
|
||||
------------
|
||||
Shared init function for SH4 drivers, uses dword for read/write ops.
|
||||
|
||||
4) pci_sh7751.c
|
||||
---------------
|
||||
Standard driver, uses SH4 shared init.
|
||||
|
||||
5) pci_sh7780.c
|
||||
---------------
|
||||
Standard driver, uses SH4 shared init.
|
||||
|
||||
6) tsi108_pci.c
|
||||
---------------
|
||||
Standard driver, uses dword for read/write ops.
|
||||
|
||||
7) fsl_pci_init.c
|
||||
-----------------
|
||||
Driver for PCI and PCI-e, uses indirect functions.
|
||||
|
||||
8) pci_ftpci100.c
|
||||
-----------------
|
||||
Standard driver, uses indirect functions, has separate scan/setup
|
||||
functions.
|
||||
|
||||
B) driver in arch/
|
||||
------------------
|
||||
|
||||
1) x86/lib/pci_type1.c
|
||||
----------------------
|
||||
Standard driver, specifies all read/write functions separately.
|
||||
|
||||
2) m68k/cpu/mcf5445x/pci.c
|
||||
--------------------------
|
||||
Standard driver, specifies all read/write functions separately.
|
||||
|
||||
3) m68k/cpu/mcf547x_8x/pci.c
|
||||
----------------------------
|
||||
Standard driver, specifies all read/write functions separately.
|
||||
|
||||
4) powerpc/cpu/mpc824x/pci.c
|
||||
----------------------------
|
||||
Standard driver, uses indirect functions, does not setup HW.
|
||||
|
||||
5) powerpc/cpu/mpc8260/pci.c
|
||||
----------------------------
|
||||
Standard driver, uses indirect functions.
|
||||
|
||||
6) powerpc/cpu/ppc4xx/4xx_pci.c
|
||||
-------------------------------
|
||||
Standard driver, uses indirect functions.
|
||||
|
||||
7) powerpc/cpu/ppc4xx/4xx_pcie.c
|
||||
--------------------------------
|
||||
PCI-e driver, specifies all read/write functions separately.
|
||||
|
||||
8) powerpc/cpu/mpc83xx/pci.c
|
||||
----------------------------
|
||||
Standard driver, uses indirect functions.
|
||||
|
||||
9) powerpc/cpu/mpc83xx/pcie.c
|
||||
-----------------------------
|
||||
PCI-e driver, specifies all read/write functions separately.
|
||||
|
||||
10) powerpc/cpu/mpc5xxx/pci_mpc5200.c
|
||||
-------------------------------------
|
||||
Standard driver, uses dword for read/write ops.
|
||||
|
||||
11) powerpc/cpu/mpc512x/pci.c
|
||||
-----------------------------
|
||||
Standard driver, uses indirect functions.
|
||||
|
||||
12) powerpc/cpu/mpc8220/pci.c
|
||||
-----------------------------
|
||||
Standard driver, specifies all read/write functions separately.
|
||||
|
||||
13) powerpc/cpu/mpc85xx/pci.c
|
||||
-----------------------------
|
||||
Standard driver, uses indirect functions, has two busses.
|
||||
|
||||
C) drivers in board/
|
||||
--------------------
|
||||
|
||||
1) eltec/elppc/pci.c
|
||||
--------------------
|
||||
Standard driver, uses indirect functions.
|
||||
|
||||
2) amirix/ap1000/pci.c
|
||||
----------------------
|
||||
Standard driver, specifies all read/write functions separately.
|
||||
|
||||
3) prodrive/p3mx/pci.c
|
||||
----------------------
|
||||
Standard driver, uses dword for read/write ops, has two busses.
|
||||
|
||||
4) esd/cpci750/pci.c
|
||||
--------------------
|
||||
Standard driver, uses dword for read/write ops, has two busses.
|
||||
|
||||
5) esd/common/pci.c
|
||||
-------------------
|
||||
Standard driver, uses dword for read/write ops.
|
||||
|
||||
6) dave/common/pci.c
|
||||
--------------------
|
||||
Standard driver, uses dword for read/write ops.
|
||||
|
||||
7) ppmc7xx/pci.c
|
||||
----------------
|
||||
Standard driver, uses indirect functions.
|
||||
|
||||
8) pcippc2/cpc710_pci.c
|
||||
-----------------------
|
||||
Standard driver, uses indirect functions, has two busses.
|
||||
|
||||
9) Marvell/db64360/pci.c
|
||||
------------------------
|
||||
Standard driver, uses dword for read/write ops, has two busses.
|
||||
|
||||
10) Marvell/db64460/pci.c
|
||||
-------------------------
|
||||
Standard driver, uses dword for read/write ops, has two busses.
|
||||
|
||||
11) evb64260/pci.c
|
||||
------------------
|
||||
Standard driver, uses dword for read/write ops, has two busses.
|
||||
|
||||
12) armltd/integrator/pci.c
|
||||
---------------------------
|
||||
Standard driver, specifies all read/write functions separately.
|
||||
|
||||
All drivers will be moved to drivers/pci. Several drivers seem
|
||||
similar/identical, especially those located under board, and may be merged
|
||||
into one.
|
Loading…
Reference in a new issue