[u-boot.git] / doc / README.imx31

U-Boot for Freescale i.MX31

This file contains information for the port of U-Boot to the Freescale
i.MX31 SoC.

1. CONFIGURATION OPTIONS/SETTINGS
---------------------------------

1.1 Configuration of MC13783 SPI bus
------------------------------------
	The power management companion chip MC13783 is connected to the
	i.MX31 via an SPI bus. Use the following configuration options
	to setup the bus and chip select used for a particular board.

	CONFIG_MC13783_SPI_BUS	-- defines the SPI bus the MC13783 is connected to.
			   Note that 0 is CSPI1, 1 is CSPI2 and 2 is CSPI3.
	CONFIG_MC13783_SPI_CS	-- define the chip select the MC13783 s connected to.

1.2 Timer precision
-------------------
	CONFIG_MX31_TIMER_HIGH_PRECISION

	Enable higher precision timer. The low-precision timer
	(default) provides approximately 4% error, whereas the
	high-precision timer is about 0.4% accurate. The extra
	accuracy is achieved at the cost of higher computational
	overhead, which, in places where time is measured, should
	not be critical, so, it should be safe to enable this
	option.
Commit	Line	Data
77a0355f JCPV	1	U-Boot for Freescale i.MX31
	2
	3	This file contains information for the port of U-Boot to the Freescale
	4	i.MX31 SoC.
	5
	6	1. CONFIGURATION OPTIONS/SETTINGS
	7	---------------------------------
	8
	9	1.1 Configuration of MC13783 SPI bus
	10	------------------------------------
	11	The power management companion chip MC13783 is connected to the
	12	i.MX31 via an SPI bus. Use the following configuration options
	13	to setup the bus and chip select used for a particular board.
	14
	15	CONFIG_MC13783_SPI_BUS -- defines the SPI bus the MC13783 is connected to.
	16	Note that 0 is CSPI1, 1 is CSPI2 and 2 is CSPI3.
	17	CONFIG_MC13783_SPI_CS -- define the chip select the MC13783 s connected to.
	18
	19	1.2 Timer precision
	20	-------------------
	21	CONFIG_MX31_TIMER_HIGH_PRECISION
	22
	23	Enable higher precision timer. The low-precision timer
	24	(default) provides approximately 4% error, whereas the
	25	high-precision timer is about 0.4% accurate. The extra
	26	accuracy is achieved at the cost of higher computational
	27	overhead, which, in places where time is measured, should
	28	not be critical, so, it should be safe to enable this
	29	option.