upstream u-boot with additional patches for our devices/boards:
https://lists.denx.de/pipermail/u-boot/2017-March/282789.html (AXP crashes) ;
Gbit ethernet patch for some LIME2 revisions ;
with SPI flash support
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
278 lines
9.8 KiB
278 lines
9.8 KiB
The U-Boot Driver Model Project
|
|
===============================
|
|
Block device subsystem analysis
|
|
===============================
|
|
|
|
Pavel Herrmann <morpheus.ibis@gmail.com>
|
|
2012-03-08
|
|
|
|
I) Overview
|
|
-----------
|
|
|
|
U-Boot currently implements several distinct APIs for block devices - some
|
|
drivers use the SATA API, some drivers use the IDE API, sym53c8xx and
|
|
AHCI use the SCSI API, mg_disk has a separate API, and systemace also has a
|
|
separate API. There are also MMC and USB APIs used outside of drivers/block,
|
|
those will be detailed in their specific documents.
|
|
|
|
Block devices are described by block_dev_desc structure, that holds, among
|
|
other things, the read/write/erase callbacks. Block device structures are
|
|
stored in any way depending on the API, but can be accessed by
|
|
|
|
block_dev_desc_t * $api_get_dev(int dev)
|
|
|
|
function, as seen in disk/part.c.
|
|
|
|
1) SATA interface
|
|
-----------------
|
|
|
|
The SATA interface drivers implement the following functions:
|
|
|
|
int init_sata(int dev)
|
|
int scan_sata(int dev)
|
|
ulong sata_read(int dev, ulong blknr, ulong blkcnt, void *buffer)
|
|
ulong sata_write(int dev, ulong blknr, ulong blkcnt, const void *buffer)
|
|
|
|
Block devices are kept in sata_dev_desc[], which is prefilled with values
|
|
common to all SATA devices in cmd_sata.c, and then modified in init_sata
|
|
function in the drivers. Callbacks of the block device use SATA API
|
|
directly. The sata_get_dev function is defined in cmd_sata.c.
|
|
|
|
2) SCSI interface
|
|
-----------------
|
|
|
|
The SCSI interface drivers implement the following functions:
|
|
|
|
void scsi_print_error(ccb *pccb)
|
|
int scsi_exec(ccb *pccb)
|
|
void scsi_bus_reset(void)
|
|
void scsi_low_level_init(int busdevfunc)
|
|
|
|
The SCSI API works through the scsi_exec function, the actual operation
|
|
requested is found in the ccb structure.
|
|
|
|
Block devices are kept in scsi_dev_desc[], which lives only in cmd_scsi.c.
|
|
Callbacks of the block device use functions from cmd_scsi.c, which in turn
|
|
call scsi_exec of the controller. The scsi_get_dev function is also defined
|
|
in cmd_scsi.c.
|
|
|
|
3) mg_disk interface
|
|
--------------------
|
|
|
|
The mg_disk interface drivers implement the following functions:
|
|
|
|
struct mg_drv_data* mg_get_drv_data (void)
|
|
uint mg_disk_init (void)
|
|
uint mg_disk_read (u32 addr, u8 *buff, u32 len)
|
|
uint mg_disk_write(u32 addr, u8 *buff, u32 len)
|
|
uint mg_disk_write_sects(void *buff, u32 sect_num, u32 sect_cnt)
|
|
uint mg_disk_read_sects(void *buff, u32 sect_num, u32 sect_cnt)
|
|
|
|
The mg_get_drv_data function is to be overridden per-board, but there are no
|
|
board in-tree that do this.
|
|
|
|
Only one driver for this API exists, and it only supports one block device.
|
|
Callbacks for this device are implemented in mg_disk.c and call the mg_disk
|
|
API. The mg_disk_get_dev function is defined in mg_disk.c and ignores the
|
|
device number, always returning the same device.
|
|
|
|
4) systemace interface
|
|
----------------------
|
|
|
|
The systemace interface does not define any driver API, and has no command
|
|
itself. The single defined function is systemace_get_devs() from
|
|
systemace.c, which returns a single static structure for the only supported
|
|
block device. Callbacks for this device are also implemented in systemace.c.
|
|
|
|
5) IDE interface
|
|
----------------
|
|
|
|
The IDE interface drivers implement the following functions, but only if
|
|
CONFIG_IDE_AHB is set:
|
|
|
|
uchar ide_read_register(int dev, unsigned int port);
|
|
void ide_write_register(int dev, unsigned int port, unsigned char val);
|
|
void ide_read_data(int dev, ulong *sect_buf, int words);
|
|
void ide_write_data(int dev, const ulong *sect_buf, int words);
|
|
|
|
The first two functions are called from ide_inb()/ide_outb(), and will
|
|
default to direct memory access if CONFIG_IDE_AHB is not set, or
|
|
ide_inb()/ide_outb() functions will get overridden by the board altogether.
|
|
|
|
The second two functions are called from input_data()/output_data()
|
|
functions, and also default to direct memory access, but cannot be
|
|
overridden by the board.
|
|
|
|
One function shared by IDE drivers (but not defined in ide.h) is
|
|
int ide_preinit(void)
|
|
This function gets called from ide_init in cmd_ide.c if CONFIG_IDE_PREINIT
|
|
is defined, and will do the driver-specific initialization of the device.
|
|
|
|
Block devices are kept in ide_dev_desc[], which is filled in cmd_ide.c.
|
|
Callbacks of the block device are defined in cmd_ide.c, and use the
|
|
ide_inb()/ide_outb()/input_data()/output_data() functions mentioned above.
|
|
The ide_get_dev function is defined in cmd_ide.c.
|
|
|
|
II) Approach
|
|
------------
|
|
|
|
A new block controller core and an associated API will be created to mimic the
|
|
current SATA API, its drivers will have the following ops:
|
|
|
|
struct block_ctrl_ops {
|
|
int scan(instance *i);
|
|
int reset(instance *i, int port);
|
|
lbaint_t read(instance *i, int port, lbaint_t start, lbatin_t length,
|
|
void *buffer);
|
|
lbaint_t write(instance *i, int port, lbaint_t start, lbatin_t length,
|
|
void*buffer);
|
|
}
|
|
|
|
The current sata_init() function will be changed into the driver probe()
|
|
function. The read() and write() functions should never be called directly,
|
|
instead they should be called by block device driver for disks.
|
|
|
|
Other block APIs would either be transformed into this API, or be kept as
|
|
legacy for old drivers, or be dropped altogether.
|
|
|
|
Legacy driver APIs will each have its own driver core that will contain the
|
|
shared logic, which is currently located mostly in cmd_* files. Callbacks for
|
|
block device drivers will then probably be implemented as a part of the core
|
|
logic, and will use the driver ops (which will copy current state of
|
|
respective APIs) to do the work.
|
|
|
|
All drivers will be cleaned up, most ifdefs should be converted into
|
|
platform_data, to enable support for multiple devices with different settings.
|
|
|
|
A new block device core will also be created, and will keep track of all
|
|
block devices on all interfaces.
|
|
|
|
Current block_dev_desc structure will be changed to fit the driver model, all
|
|
identification and configuration will be placed in private data, and
|
|
a single accessor and modifier will be defined, to accommodate the need for
|
|
different sets of options for different interfaces, while keeping the
|
|
structure small. The new block device drivers will have the following ops
|
|
structure (lbaint_t is either 32bit or 64bit unsigned, depending on
|
|
CONFIG_LBA48):
|
|
|
|
struct blockdev_ops {
|
|
lbaint_t (*block_read)(struct instance *i, lbaint_t start, lbaint_t blkcnt,
|
|
void *buffer);
|
|
lbaint_t (*block_write)(struct instance *i, lbaint_t start, lbaint_t blkcnt,
|
|
void *buffer);
|
|
lbaint_t (*block_erase)(struct instance *i, lbaint_t start, lbaint_t blkcnt
|
|
);
|
|
int (*get_option)(struct instance *i, enum blockdev_option_code op,
|
|
struct option *res);
|
|
int (*set_option)(struct instance *i, enum blockdev_option_code op,
|
|
struct option *val);
|
|
}
|
|
|
|
struct option {
|
|
uint32_t flags
|
|
union data {
|
|
uint64_t data_u;
|
|
char* data_s;
|
|
void* data_p;
|
|
}
|
|
}
|
|
|
|
enum blockdev_option_code {
|
|
BLKD_OPT_IFTYPE=0,
|
|
BLKD_OPT_TYPE,
|
|
BLKD_OPT_BLOCKSIZE,
|
|
BLKD_OPT_BLOCKCOUNT,
|
|
BLKD_OPT_REMOVABLE,
|
|
BLKD_OPT_LBA48,
|
|
BLKD_OPT_VENDOR,
|
|
BLKD_OPT_PRODICT,
|
|
BLKD_OPT_REVISION,
|
|
BLKD_OPT_SCSILUN,
|
|
BLKD_OPT_SCSITARGET,
|
|
BLKD_OPT_OFFSET
|
|
}
|
|
|
|
Flags in option above will contain the type of returned data (which should be
|
|
checked against what is expected, even though the option requested should
|
|
specify it), and a flag to indicate whether the returned pointer needs to be
|
|
free()'d.
|
|
|
|
The block device core will contain the logic now located in disk/part.c and
|
|
related files, and will be used to forward requests to block devices. The API
|
|
for the block device core will copy the ops of a block device (with a string
|
|
identifier instead of instance pointer). This means that partitions will also
|
|
be handled by the block device core, and exported as block devices, making
|
|
them transparent to the rest of the code.
|
|
|
|
Sadly, this will change how file systems can access the devices, and thus will
|
|
affect a lot of places. However, these changes should be localized and easy to
|
|
implement.
|
|
|
|
AHCI driver will be rewritten to fit the new unified block controller API,
|
|
making SCSI API easy to merge with sym53c8xx, or remove it once the device
|
|
driver has died.
|
|
|
|
Optionally, IDE core may be changed into one driver with unified block
|
|
controller API, as most of it is already in one place and device drivers are
|
|
just sets of hooks. Additionally, mg_disk driver is unused and may be removed
|
|
in near future.
|
|
|
|
|
|
III) Analysis of in-tree drivers
|
|
--------------------------------
|
|
|
|
1) ahci.c
|
|
---------
|
|
SCSI API, will be rewritten for a different API.
|
|
|
|
2) ata_piix.c
|
|
-------------
|
|
SATA API, easy to port.
|
|
|
|
3) fsl_sata.c
|
|
-------------
|
|
SATA API, few CONFIG macros, easy to port.
|
|
|
|
4) ftide020.c
|
|
-------------
|
|
IDE API, defines CONFIG_IDE_AHB and ide_preinit hook functions.
|
|
|
|
5) mg_disk.c
|
|
------------
|
|
Single driver with mg_disk API, not much to change, easy to port.
|
|
|
|
6) mvsata_ide.c
|
|
---------------
|
|
IDE API, only defines ide_preinit hook function.
|
|
|
|
7) mxc_ata.c
|
|
------------
|
|
IDE API, only defines ide_preinit hook function.
|
|
|
|
8) pata_bfin.c
|
|
--------------
|
|
SATA API, easy to port.
|
|
|
|
9) sata_dwc.c
|
|
-------------
|
|
SATA API, easy to port.
|
|
|
|
10) sata_sil3114.c
|
|
------------------
|
|
SATA API, easy to port.
|
|
|
|
11) sata_sil.c
|
|
--------------
|
|
SATA API, easy to port.
|
|
|
|
12) sil680.c
|
|
------------
|
|
IDE API, only defines ide_preinit hook function.
|
|
|
|
13) sym53c8xx.c
|
|
---------------
|
|
SCSI API, may be merged with code from cmd_scsi.
|
|
|
|
14) systemace.c
|
|
---------------
|
|
Single driver with systemace API, not much to change, easy to port.
|
|
|