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Commit 38687ae67664d0f7ee907a2053d4a0663744b7b4

Authored by Simon Glass
1 parent f8fff9dac9
Exists in v2017.01-smarct4x and in 37 other branches 8qm-imx_v2020.04_5.4.70_2.3.0, emb_lf_v2022.04, imx_v2015.04_4.1.15_1.0.0_ga, pitx_8mp_lf_v2020.04, smarc-8m-android-10.0.0_2.6.0, smarc-8m-android-11.0.0_2.0.0, smarc-8mp-android-11.0.0_2.0.0, smarc-imx6_v2018.03_4.14.98_2.0.0_ga, smarc-imx7_v2017.03_4.9.11_1.0.0_ga, smarc-imx7_v2018.03_4.14.98_2.0.0_ga, smarc-imx_v2015.04_4.1.15_1.0.0_ga, smarc-imx_v2017.03_4.9.11_1.0.0_ga, smarc-imx_v2017.03_4.9.88_2.0.0_ga, smarc-imx_v2017.03_o8.1.0_1.3.0_8m, smarc-imx_v2018.03_4.14.78_1.0.0_ga, smarc-m6.0.1_2.1.0-ga, smarc-n7.1.2_2.0.0-ga, smarc-rel_imx_4.1.15_2.0.0_ga, smarc_8m-imx_v2018.03_4.14.98_2.0.0_ga, smarc_8m-imx_v2019.04_4.19.35_1.1.0, smarc_8m_00d0-imx_v2018.03_4.14.98_2.0.0_ga, smarc_8mm-imx_v2018.03_4.14.98_2.0.0_ga, smarc_8mm-imx_v2019.04_4.19.35_1.1.0, smarc_8mm-imx_v2020.04_5.4.24_2.1.0, smarc_8mp_lf_v2020.04, smarc_8mq-imx_v2020.04_5.4.24_2.1.0, smarc_8mq_lf_v2020.04, ti-u-boot-2015.07, v2015.07-smarct33, v2015.07-smarct33-emmc, v2015.07-smarct4x, v2016.05-dlt, v2016.05-smarct3x, v2016.05-smarct3x-emmc, v2016.05-smarct4x, v2017.01-smarct3x, v2017.01-smarct3x-emmc

dm: Update documentation to include CONFIG_DM... options 

Add documentation for the various driver model options that are now
available.

Signed-off-by: Simon Glass <sjg@chromium.org>

Showing 2 changed files with 153 additions and 10 deletions Side-by-side Diff

... ... @@ -623,6 +623,120 @@
623 623 exists, unlike the similar options in the Linux kernel. Do not
624 624 set these options unless they apply!
625 625  
  626 +- Driver Model
  627 + Driver model is a new framework for devices in U-Boot
  628 + introduced in early 2014. U-Boot is being progressively
  629 + moved over to this. It offers a consistent device structure,
  630 + supports grouping devices into classes and has built-in
  631 + handling of platform data and device tree.
  632 +
  633 + To enable transition to driver model in a relatively
  634 + painful fashion, each subsystem can be independently
  635 + switched between the legacy/ad-hoc approach and the new
  636 + driver model using the options below. Also, many uclass
  637 + interfaces include compatibility features which may be
  638 + removed once the conversion of that subsystem is complete.
  639 + As a result, the API provided by the subsystem may in fact
  640 + not change with driver model.
  641 +
  642 + See doc/driver-model/README.txt for more information.
  643 +
  644 + CONFIG_DM
  645 +
  646 + Enable driver model. This brings in the core support,
  647 + including scanning of platform data on start-up. If
  648 + CONFIG_OF_CONTROL is enabled, the device tree will be
  649 + scanned also when available.
  650 +
  651 + CONFIG_CMD_DM
  652 +
  653 + Enable driver model test commands. These allow you to print
  654 + out the driver model tree and the uclasses.
  655 +
  656 + CONFIG_DM_DEMO
  657 +
  658 + Enable some demo devices and the 'demo' command. These are
  659 + really only useful for playing around while trying to
  660 + understand driver model in sandbox.
  661 +
  662 + CONFIG_SPL_DM
  663 +
  664 + Enable driver model in SPL. You will need to provide a
  665 + suitable malloc() implementation. If you are not using the
  666 + full malloc() enabled by CONFIG_SYS_SPL_MALLOC_START,
  667 + consider using CONFIG_SYS_MALLOC_SIMPLE. In that case you
  668 + must provide CONFIG_SYS_MALLOC_F_LEN to set the size.
  669 + In most cases driver model will only allocate a few uclasses
  670 + and devices in SPL, so 1KB should be enable. See
  671 + CONFIG_SYS_MALLOC_F_LEN for more details on how to enable
  672 + it.
  673 +
  674 + CONFIG_DM_SERIAL
  675 +
  676 + Enable driver model for serial. This replaces
  677 + drivers/serial/serial.c with the serial uclass, which
  678 + implements serial_putc() etc. The uclass interface is
  679 + defined in include/serial.h.
  680 +
  681 + CONFIG_DM_GPIO
  682 +
  683 + Enable driver model for GPIO access. The standard GPIO
  684 + interface (gpio_get_value(), etc.) is then implemented by
  685 + the GPIO uclass. Drivers provide methods to query the
  686 + particular GPIOs that they provide. The uclass interface
  687 + is defined in include/asm-generic/gpio.h.
  688 +
  689 + CONFIG_DM_SPI
  690 +
  691 + Enable driver model for SPI. The SPI slave interface
  692 + (spi_setup_slave(), spi_xfer(), etc.) is then implemented by
  693 + the SPI uclass. Drivers provide methods to access the SPI
  694 + buses that they control. The uclass interface is defined in
  695 + include/spi.h. The existing spi_slave structure is attached
  696 + as 'parent data' to every slave on each bus. Slaves
  697 + typically use driver-private data instead of extending the
  698 + spi_slave structure.
  699 +
  700 + CONFIG_DM_SPI_FLASH
  701 +
  702 + Enable driver model for SPI flash. This SPI flash interface
  703 + (spi_flash_probe(), spi_flash_write(), etc.) is then
  704 + implemented by the SPI flash uclass. There is one standard
  705 + SPI flash driver which knows how to probe most chips
  706 + supported by U-Boot. The uclass interface is defined in
  707 + include/spi_flash.h, but is currently fully compatible
  708 + with the old interface to avoid confusion and duplication
  709 + during the transition parent. SPI and SPI flash must be
  710 + enabled together (it is not possible to use driver model
  711 + for one and not the other).
  712 +
  713 + CONFIG_DM_CROS_EC
  714 +
  715 + Enable driver model for the Chrome OS EC interface. This
  716 + allows the cros_ec SPI driver to operate with CONFIG_DM_SPI
  717 + but otherwise makes few changes. Since cros_ec also supports
  718 + I2C and LPC (which don't support driver model yet), a full
  719 + conversion is not yet possible.
  720 +
  721 +
  722 + ** Code size options: The following options are enabled by
  723 + default except in SPL. Enable them explicitly to get these
  724 + features in SPL.
  725 +
  726 + CONFIG_DM_WARN
  727 +
  728 + Enable the dm_warn() function. This can use up quite a bit
  729 + of space for its strings.
  730 +
  731 + CONFIG_DM_STDIO
  732 +
  733 + Enable registering a serial device with the stdio library.
  734 +
  735 + CONFIG_DM_DEVICE_REMOVE
  736 +
  737 + Enable removing of devices.
  738 +
  739 +
626 740 - Linux Kernel Interface:
627 741 CONFIG_CLOCKS_IN_MHZ
628 742  
... ... @@ -3880,6 +3994,11 @@
3880 3994  
3881 3995 Pre-relocation malloc() is only supported on ARM and sandbox
3882 3996 at present but is fairly easy to enable for other archs.
  3997 +
  3998 +- CONFIG_SYS_MALLOC_SIMPLE
  3999 + Provides a simple and small malloc() and calloc() for those
  4000 + boards which do not use the full malloc in SPL (which is
  4001 + enabled with CONFIG_SYS_SPL_MALLOC_START).
3883 4002  
3884 4003 - CONFIG_SYS_BOOTM_LEN:
3885 4004 Normally compressed uImages are limited to an
doc/driver-model/README.txt
Diff comments   View file @ 38687ae
... ... @@ -750,19 +750,43 @@
750 750 pointer is saved but not made available through the driver model API).
751 751  
752 752  
753   -Things to punt for later
754   -------------------------
  753 +SPL Support
  754 +-----------
755 755  
756   -- SPL support - this will have to be present before many drivers can be
757   -converted, but it seems like we can add it once we are happy with the
758   -core implementation.
  756 +Driver model can operate in SPL. Its efficient implementation and small code
  757 +size provide for a small overhead which is acceptable for all but the most
  758 +constrained systems.
759 759  
760   -That is not to say that no thinking has gone into this - in fact there
761   -is quite a lot there. However, getting these right is non-trivial and
762   -there is a high cost associated with going down the wrong path.
  760 +To enable driver model in SPL, define CONFIG_SPL_DM. You might want to
  761 +consider the following option also. See the main README for more details.
763 762  
764   -For SPL, it may be possible to fit in a simplified driver model with only
765   -bind and probe methods, to reduce size.
  763 + - CONFIG_SYS_MALLOC_SIMPLE
  764 + - CONFIG_DM_WARN
  765 + - CONFIG_DM_DEVICE_REMOVE
  766 + - CONFIG_DM_STDIO
  767 +
  768 +
  769 +Enabling Driver Model
  770 +---------------------
  771 +
  772 +Driver model is being brought into U-Boot gradually. As each subsystems gets
  773 +support, a uclass is created and a CONFIG to enable use of driver model for
  774 +that subsystem.
  775 +
  776 +For example CONFIG_DM_SERIAL enables driver model for serial. With that
  777 +defined, the old serial support is not enabled, and your serial driver must
  778 +conform to driver model. With that undefined, the old serial support is
  779 +enabled and driver model is not available for serial. This means that when
  780 +you convert a driver, you must either convert all its boards, or provide for
  781 +the driver to be compiled both with and without driver model (generally this
  782 +is not very hard).
  783 +
  784 +See the main README for full details of the available driver model CONFIG
  785 +options.
  786 +
  787 +
  788 +Things to punt for later
  789 +------------------------
766 790  
767 791 Uclasses are statically numbered at compile time. It would be possible to
768 792 change this to dynamic numbering, but then we would require some sort of