diff options
| author | Thomas Petazzoni <thomas.petazzoni@free-electrons.com> | 2017-04-29 11:06:45 +0200 |
|---|---|---|
| committer | Boris Brezillon <boris.brezillon@free-electrons.com> | 2017-06-01 10:09:23 +0200 |
| commit | 9748e1d87573c94191442d6bd0307f523e5cd8b8 (patch) | |
| tree | 4ec53f7f79c586f708b5bad6f3aecbe9292e2fed /include/linux/mtd | |
| parent | 4a78cc644eed3cf2dae00c3a959910a86c140fd6 (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.h | 2 |
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 |