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authorThomas Petazzoni <thomas.petazzoni@free-electrons.com>2017-04-29 11:06:45 +0200
committerBoris Brezillon <boris.brezillon@free-electrons.com>2017-06-01 10:09:23 +0200
commit9748e1d87573c94191442d6bd0307f523e5cd8b8 (patch)
tree4ec53f7f79c586f708b5bad6f3aecbe9292e2fed /include/linux/mtd
parent4a78cc644eed3cf2dae00c3a959910a86c140fd6 (diff)
mtd: nand: add support for Micron on-die ECC
Now that the core NAND subsystem has support for on-die ECC, this commit brings the necessary code to support on-die ECC on Micron NANDs. In micron_nand_init(), we detect if the Micron NAND chip supports on-die ECC mode, by checking a number of conditions: - It must be an ONFI NAND - It must be a SLC NAND - Enabling *and* disabling on-die ECC must work - The on-die ECC must be correcting 4 bits per 512 bytes of data. Some Micron NAND chips have an on-die ECC able to correct 8 bits per 512 bytes of data, but they work slightly differently and therefore we don't support them in this patch. Then, if the on-die ECC cannot be disabled (some Micron NAND have on-die ECC forcefully enabled), we bail out, as we don't support such NANDs. Indeed, the implementation of raw_read()/raw_write() make the assumption that on-die ECC can be disabled. Support for Micron NANDs with on-die ECC forcefully enabled can easily be added, but in the absence of such HW for testing, we preferred to simply bail out. If the on-die ECC is supported, and requested in the Device Tree, then it is indeed enabled, by using custom implementations of the ->read_page(), ->read_page_raw(), ->write_page() and ->write_page_raw() operation to properly handle the on-die ECC. In the non-raw functions, we need to enable the internal ECC engine before issuing the NAND_CMD_READ0 or NAND_CMD_SEQIN commands, which is why we set the NAND_ECC_CUSTOM_PAGE_ACCESS option at initialization time (it asks the NAND core to let the NAND driver issue those commands). Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com> Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Diffstat (limited to 'include/linux/mtd')
-rw-r--r--include/linux/mtd/nand.h2
1 files changed, 2 insertions, 0 deletions
diff --git a/include/linux/mtd/nand.h b/include/linux/mtd/nand.h
index 28f7dd9177e9..893d0ce08030 100644
--- a/include/linux/mtd/nand.h
+++ b/include/linux/mtd/nand.h
@@ -258,6 +258,8 @@ struct nand_chip;
/* Vendor-specific feature address (Micron) */
#define ONFI_FEATURE_ADDR_READ_RETRY 0x89
+#define ONFI_FEATURE_ON_DIE_ECC 0x90
+#define ONFI_FEATURE_ON_DIE_ECC_EN BIT(3)
/* ONFI subfeature parameters length */
#define ONFI_SUBFEATURE_PARAM_LEN 4