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Diffstat (limited to 'README')
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@@ -623,6 +623,120 @@ The following options need to be configured: exists, unlike the similar options in the Linux kernel. Do not set these options unless they apply! +- Driver Model + Driver model is a new framework for devices in U-Boot + introduced in early 2014. U-Boot is being progressively + moved over to this. It offers a consistent device structure, + supports grouping devices into classes and has built-in + handling of platform data and device tree. + + To enable transition to driver model in a relatively + painful fashion, each subsystem can be independently + switched between the legacy/ad-hoc approach and the new + driver model using the options below. Also, many uclass + interfaces include compatibility features which may be + removed once the conversion of that subsystem is complete. + As a result, the API provided by the subsystem may in fact + not change with driver model. + + See doc/driver-model/README.txt for more information. + + CONFIG_DM + + Enable driver model. This brings in the core support, + including scanning of platform data on start-up. If + CONFIG_OF_CONTROL is enabled, the device tree will be + scanned also when available. + + CONFIG_CMD_DM + + Enable driver model test commands. These allow you to print + out the driver model tree and the uclasses. + + CONFIG_DM_DEMO + + Enable some demo devices and the 'demo' command. These are + really only useful for playing around while trying to + understand driver model in sandbox. + + CONFIG_SPL_DM + + Enable driver model in SPL. You will need to provide a + suitable malloc() implementation. If you are not using the + full malloc() enabled by CONFIG_SYS_SPL_MALLOC_START, + consider using CONFIG_SYS_MALLOC_SIMPLE. In that case you + must provide CONFIG_SYS_MALLOC_F_LEN to set the size. + In most cases driver model will only allocate a few uclasses + and devices in SPL, so 1KB should be enable. See + CONFIG_SYS_MALLOC_F_LEN for more details on how to enable + it. + + CONFIG_DM_SERIAL + + Enable driver model for serial. This replaces + drivers/serial/serial.c with the serial uclass, which + implements serial_putc() etc. The uclass interface is + defined in include/serial.h. + + CONFIG_DM_GPIO + + Enable driver model for GPIO access. The standard GPIO + interface (gpio_get_value(), etc.) is then implemented by + the GPIO uclass. Drivers provide methods to query the + particular GPIOs that they provide. The uclass interface + is defined in include/asm-generic/gpio.h. + + CONFIG_DM_SPI + + Enable driver model for SPI. The SPI slave interface + (spi_setup_slave(), spi_xfer(), etc.) is then implemented by + the SPI uclass. Drivers provide methods to access the SPI + buses that they control. The uclass interface is defined in + include/spi.h. The existing spi_slave structure is attached + as 'parent data' to every slave on each bus. Slaves + typically use driver-private data instead of extending the + spi_slave structure. + + CONFIG_DM_SPI_FLASH + + Enable driver model for SPI flash. This SPI flash interface + (spi_flash_probe(), spi_flash_write(), etc.) is then + implemented by the SPI flash uclass. There is one standard + SPI flash driver which knows how to probe most chips + supported by U-Boot. The uclass interface is defined in + include/spi_flash.h, but is currently fully compatible + with the old interface to avoid confusion and duplication + during the transition parent. SPI and SPI flash must be + enabled together (it is not possible to use driver model + for one and not the other). + + CONFIG_DM_CROS_EC + + Enable driver model for the Chrome OS EC interface. This + allows the cros_ec SPI driver to operate with CONFIG_DM_SPI + but otherwise makes few changes. Since cros_ec also supports + I2C and LPC (which don't support driver model yet), a full + conversion is not yet possible. + + + ** Code size options: The following options are enabled by + default except in SPL. Enable them explicitly to get these + features in SPL. + + CONFIG_DM_WARN + + Enable the dm_warn() function. This can use up quite a bit + of space for its strings. + + CONFIG_DM_STDIO + + Enable registering a serial device with the stdio library. + + CONFIG_DM_DEVICE_REMOVE + + Enable removing of devices. + + - Linux Kernel Interface: CONFIG_CLOCKS_IN_MHZ @@ -3881,6 +3995,11 @@ Configuration Settings: Pre-relocation malloc() is only supported on ARM and sandbox at present but is fairly easy to enable for other archs. +- CONFIG_SYS_MALLOC_SIMPLE + Provides a simple and small malloc() and calloc() for those + boards which do not use the full malloc in SPL (which is + enabled with CONFIG_SYS_SPL_MALLOC_START). + - CONFIG_SYS_BOOTM_LEN: Normally compressed uImages are limited to an uncompressed size of 8 MBytes. If this is not enough, |