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https://github.com/AsahiLinux/u-boot
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3f719069c8
This patch adds new CONFIG_NAND_OMAP_ECCSCHEME, replacing other distributed
CONFIG_xx used for selecting NAND ecc-schemes.
This patch aims at solving following issues.
1) Currently ecc-scheme is tied to SoC platform, which prevents user to select
other ecc-schemes also supported in hardware. like;
- most of OMAP3 SoC platforms use only 1-bit Hamming ecc-scheme, inspite
the fact that they can use higher ecc-schemes like 8-bit ecc-schemes with
software based error detection (OMAP_ECC_BCH4_CODE_HW_DETECTION_SW).
- most of AM33xx SoC plaforms use 8-bit BCH ecc-scheme for now, but hardware
supports BCH16 ecc-scheme also.
2) Different platforms use different CONFIG_xx to select ecc-schemes, which
adds confusion for user while migrating platforms.
- *CONFIG_NAND_OMAP_ELM* which enables ELM hardware engine, selects only
8-bit BCH ecc-scheme with h/w based error-correction (OMAP_ECC_BCH8_CODE_HW)
whereas ELM hardware engine supports other ecc-schemes also like; BCH4,
and BCH16 (in future).
- *CONFIG_NAND_OMAP_BCH8* selects 8-bit BCH ecc-scheme with s/w based error
correction (OMAP_ECC_BCH8_CODE_HW_DETECTION_SW).
- *CONFIG_SPL_NAND_SOFTECC* selects 1-bit Hamming ecc-scheme using s/w library
Thus adding new *CONFIG_NAND_OMAP_ECCSCHEME* de-couples ecc-scheme dependency
on SoC platform and NAND driver. And user can select ecc-scheme independently
foreach board.
However, selection some hardware based ecc-schemes (OMAP_ECC_BCHx_CODE_HW) still
depends on presence of ELM hardware engine on SoC. (Refer doc/README.nand)
Signed-off-by: Pekon Gupta <pekon@ti.com>
220 lines
4.6 KiB
Text
220 lines
4.6 KiB
Text
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Summary
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=======
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This README is about U-Boot support for TI's ARM Cortex-A8 based OMAP3 [1]
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family of SoCs. TI's OMAP3 SoC family contains an ARM Cortex-A8. Additionally,
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some family members contain a TMS320C64x+ DSP and/or an Imagination SGX 2D/3D
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graphics processor and various other standard peripherals.
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Currently the following boards are supported:
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* OMAP3530 BeagleBoard [2]
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* Gumstix Overo [3]
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* TI EVM [4]
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* OpenPandora Ltd. Pandora [5]
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* TI/Logic PD Zoom MDK [6]
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* TI/Logic PD Zoom 2 [7]
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* CompuLab Ltd. CM-T35 [8]
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Toolchain
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=========
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While ARM Cortex-A8 support ARM v7 instruction set (-march=armv7a) we compile
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with -march=armv5 to allow more compilers to work. For U-Boot code this has
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no performance impact.
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Build
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=====
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* BeagleBoard:
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make omap3_beagle_config
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make
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* Gumstix Overo:
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make omap3_overo_config
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make
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* TI EVM:
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make omap3_evm_config
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make
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* Pandora:
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make omap3_pandora_config
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make
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* Zoom MDK:
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make omap3_zoom1_config
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make
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* Zoom 2:
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make omap3_zoom2_config
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make
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* CM-T35:
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make cm_t35_config
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make
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* BlueLYNX-X:
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make omap3_mvblx_config
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make
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Custom commands
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===============
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To make U-Boot for OMAP3 support NAND device SW or HW ECC calculation, U-Boot
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for OMAP3 supports custom user command
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nandecc hw/sw
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To be compatible with NAND drivers using SW ECC (e.g. kernel code)
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nandecc sw
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enables SW ECC calculation. HW ECC enabled with
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nandecc hw
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is typically used to write 2nd stage bootloader (known as 'x-loader') which is
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executed by OMAP3's boot rom and therefore has to be written with HW ECC.
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For all other commands see
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help
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Interfaces
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==========
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gpio
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----
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To set a bit :
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if (!gpio_request(N, "")) {
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gpio_direction_output(N, 0);
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gpio_set_value(N, 1);
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}
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To clear a bit :
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if (!gpio_request(N, "")) {
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gpio_direction_output(N, 0);
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gpio_set_value(N, 0);
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}
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To read a bit :
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if (!gpio_request(N, "")) {
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gpio_direction_input(N);
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val = gpio_get_value(N);
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gpio_free(N);
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}
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if (val)
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printf("GPIO N is set\n");
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else
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printf("GPIO N is clear\n");
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dma
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---
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void omap3_dma_init(void)
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Init the DMA module
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int omap3_dma_get_conf_chan(uint32_t chan, struct dma4_chan *config);
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Read config of the channel
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int omap3_dma_conf_chan(uint32_t chan, struct dma4_chan *config);
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Write config to the channel
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int omap3_dma_conf_transfer(uint32_t chan, uint32_t *src, uint32_t *dst,
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uint32_t sze)
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Config source, destination and size of a transfer
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int omap3_dma_wait_for_transfer(uint32_t chan)
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Wait for a transfer to end - this hast to be called before a channel
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or the data the channel transferd are used.
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int omap3_dma_get_revision(uint32_t *minor, uint32_t *major)
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Read silicon Revision of the DMA module
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NAND
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====
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There are some OMAP3 devices out there with NAND attached. Due to the fact that
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OMAP3 ROM code can only handle 1-bit hamming ECC for accessing first page
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(place where SPL lives) we require this setup for u-boot at least when reading
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the second progam within SPL. A lot of newer NAND chips however require more
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than 1-bit ECC for the pages, some can live with 1-bit for the first page. To
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handle this we can switch to another ECC algorithm after reading the payload
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within SPL.
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BCH8
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----
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To enable hardware assisted BCH8 (8-bit BCH [Bose, Chaudhuri, Hocquenghem]) on
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OMAP3 devices we can use the BCH library in lib/bch.c. To do so add CONFIG_BCH
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and set CONFIG_NAND_OMAP_ECCSCHEME=5 (refer README.nand) for selecting BCH8_SW.
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The NAND OOB layout is the same as in linux kernel, if the linux kernel BCH8
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implementation for OMAP3 works for you so the u-boot version should also.
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When you require the SPL to read with BCH8 there are two more configs to
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change:
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* CONFIG_SYS_NAND_ECCPOS (must be the same as .eccpos in
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GPMC_NAND_HW_BCH8_ECC_LAYOUT defined in
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arch/arm/include/asm/arch-omap3/omap_gpmc.h)
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* CONFIG_SYS_NAND_ECCSIZE must be 512
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* CONFIG_SYS_NAND_ECCBYTES must be 13 for this BCH8 setup
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Acknowledgements
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================
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OMAP3 U-Boot is based on U-Boot tar ball [9] for BeagleBoard and EVM done by
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several TI employees.
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Links
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=====
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[1] OMAP3:
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http://www.ti.com/omap3 (high volume) and
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http://www.ti.com/omap35x (broad market)
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[2] OMAP3530 BeagleBoard:
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http://beagleboard.org/
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[3] Gumstix Overo:
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http://www.gumstix.net/Overo/
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[4] TI EVM:
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http://focus.ti.com/docs/toolsw/folders/print/tmdxevm3503.html
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[5] OpenPandora Ltd. Pandora:
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http://openpandora.org/
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[6] TI/Logic PD Zoom MDK:
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http://www.logicpd.com/products/devkit/ti/zoom_mobile_development_kit
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[7] TI/Logic PD Zoom 2
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http://www.logicpd.com/sites/default/files/1012659A_Zoom_OMAP34x-II_MDP_Brief.pdf
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[8] CompuLab Ltd. CM-T35:
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http://www.compulab.co.il/t3530/html/t3530-cm-datasheet.htm
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[9] TI OMAP3 U-Boot:
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http://beagleboard.googlecode.com/files/u-boot_beagle_revb.tar.gz
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