Commit d016dc42 authored by pekon gupta's avatar pekon gupta Committed by Scott Wood

mtd: nand: omap: enable BCH ECC scheme using ELM for generic platform

BCH8_ECC scheme implemented in omap_gpmc.c driver has following favours
+-----------------------------------+-----------------+-----------------+
|ECC Scheme                         | ECC Calculation | Error Detection |
+-----------------------------------+-----------------+-----------------+
|OMAP_ECC_BCH8_CODE_HW              |GPMC             |ELM H/W engine   |
|OMAP_ECC_BCH8_CODE_HW_DETECTION_SW |GPMC             |S/W BCH library  |
+-----------------------------------+-----------------+-----------------+

Current implementation limits the BCH8_CODE_HW only for AM33xx device family.
(using CONFIG_AM33XX). However, other SoC families (like TI81xx) also have
ELM hardware module, and can support ECC error detection using ELM.

This patch
- removes CONFIG_AM33xx
	Thus this driver can be reused by all devices having ELM h/w engine.
- adds omap_select_ecc_scheme()
	A common function to handle ecc-scheme related configurations. This
	can be used both during device-probe and via user-space u-boot commads
	to change ecc-scheme. During device probe ecc-scheme is selected based
	on CONFIG_NAND_OMAP_ELM or CONFIG_NAND_OMAP_BCH8
- enables CONFIG_BCH
	S/W library (lib/bch.c) required by OMAP_ECC_BCHx_CODE_HW_DETECTION_SW
  	is enabled by CONFIG_BCH.
- enables CONFIG_SYS_NAND_ONFI_DETECTION
	for auto-detection of ONFI compliant NAND devices
- updates following README doc
	doc/README.nand
	board/ti/am335x/README
	doc/README.omap3
Signed-off-by: default avatarPekon Gupta <pekon@ti.com>
[scottwood@freescale.com: fixed unused variable warning]
Signed-off-by: default avatarScott Wood <scottwood@freescale.com>
parent beba5f04
......@@ -68,4 +68,20 @@
}
#endif
enum omap_ecc {
/* 1-bit ECC calculation by Software, Error detection by Software */
OMAP_ECC_HAM1_CODE_SW = 1, /* avoid un-initialized int can be 0x0 */
/* 1-bit ECC calculation by GPMC, Error detection by Software */
/* ECC layout compatible to legacy ROMCODE. */
OMAP_ECC_HAM1_CODE_HW,
/* 4-bit ECC calculation by GPMC, Error detection by Software */
OMAP_ECC_BCH4_CODE_HW_DETECTION_SW,
/* 4-bit ECC calculation by GPMC, Error detection by ELM */
OMAP_ECC_BCH4_CODE_HW,
/* 8-bit ECC calculation by GPMC, Error detection by Software */
OMAP_ECC_BCH8_CODE_HW_DETECTION_SW,
/* 8-bit ECC calculation by GPMC, Error detection by ELM */
OMAP_ECC_BCH8_CODE_HW,
};
#endif /* __ASM_OMAP_GPMC_H */
......@@ -180,6 +180,17 @@ Configuration Options:
flexibility, so that one day we can eliminate the old mechanism.
CONFIG_SYS_NAND_ONFI_DETECTION
Enables detection of ONFI compliant devices during probe.
And fetching device parameters flashed on device, by parsing
ONFI parameter page.
CONFIG_BCH
Enables software based BCH ECC algorithm present in lib/bch.c
This is used by SoC platforms which do not have built-in ELM
hardware engine required for BCH ECC correction.
Platform specific options
=========================
CONFIG_NAND_OMAP_GPMC
......
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