mtd: nand: ecc-hamming: Let the software Hamming ECC engine be unselected

There is no reason to always embed the software Hamming ECC engine
implementation. By default it is (with raw NAND), but we can let the
user decide.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20200929230124.31491-19-miquel.raynal@bootlin.com

diff --git a/drivers/mtd/nand/Kconfig b/drivers/mtd/nand/Kconfig
index 306c33ca3448ca24a6d96ae2db5811fdbb8651b1..15ffe1a1b86313527a7b9744339777605bf568e0 100644 (file)
--- a/drivers/mtd/nand/Kconfig
+++ b/drivers/mtd/nand/Kconfig
@@ -16,7 +16,16 @@ config MTD_NAND_ECC
        depends on MTD_NAND_CORE
 
 config MTD_NAND_ECC_SW_HAMMING
-       bool
+       bool "Software Hamming ECC engine"
+       default y if MTD_RAW_NAND
+       select MTD_NAND_ECC
+       help
+         This enables support for software Hamming error
+         correction. This correction can correct up to 1 bit error
+         per chunk and detect up to 2 bit errors. While it used to be
+         widely used with old parts, newer NAND chips usually require
+         more strength correction and in this case BCH or RS will be
+         preferred.
 
 config MTD_NAND_ECC_SW_HAMMING_SMC
        bool "NAND ECC Smart Media byte order"

diff --git a/drivers/mtd/nand/raw/Kconfig b/drivers/mtd/nand/raw/Kconfig
index 6149096e32cb64c34823b16ad93b58e24aa0364f..cc86d6e4e04221c09c11f88a725d97cae8b54c52 100644 (file)
--- a/drivers/mtd/nand/raw/Kconfig
+++ b/drivers/mtd/nand/raw/Kconfig
@@ -3,7 +3,6 @@ menuconfig MTD_RAW_NAND
        tristate "Raw/Parallel NAND Device Support"
        select MTD_NAND_CORE
        select MTD_NAND_ECC
-       select MTD_NAND_ECC_SW_HAMMING
        help
          This enables support for accessing all type of raw/parallel
          NAND flash devices. For further information see
@@ -72,6 +71,7 @@ config MTD_NAND_AU1550
 config MTD_NAND_NDFC
        tristate "IBM/MCC 4xx NAND controller"
        depends on 4xx
+       select MTD_NAND_ECC_SW_HAMMING
        select MTD_NAND_ECC_SW_HAMMING_SMC
        help
          NDFC Nand Flash Controllers are integrated in IBM/AMCC's 4xx SoCs

diff --git a/include/linux/mtd/nand-ecc-sw-hamming.h b/include/linux/mtd/nand-ecc-sw-hamming.h
index 9d4b4d623741d9fe319ae561e5fa2ef89827d33b..5a39e96c3546e068decfcd9a00556c371eb9e7a3 100644 (file)
--- a/include/linux/mtd/nand-ecc-sw-hamming.h
+++ b/include/linux/mtd/nand-ecc-sw-hamming.h
@@ -32,6 +32,8 @@ struct nand_ecc_sw_hamming_conf {
        unsigned int sm_order;
 };
 
+#if IS_ENABLED(CONFIG_MTD_NAND_ECC_SW_HAMMING)
+
 int ecc_sw_hamming_calculate(const unsigned char *buf, unsigned int step_size,
                             unsigned char *code, bool sm_order);
 int nand_ecc_sw_hamming_calculate(struct nand_device *nand,
@@ -44,4 +46,38 @@ int nand_ecc_sw_hamming_correct(struct nand_device *nand, unsigned char *buf,
                                unsigned char *read_ecc,
                                unsigned char *calc_ecc);
 
+#else /* !CONFIG_MTD_NAND_ECC_SW_HAMMING */
+
+static inline int ecc_sw_hamming_calculate(const unsigned char *buf,
+                                          unsigned int step_size,
+                                          unsigned char *code, bool sm_order)
+{
+       return -ENOTSUPP;
+}
+
+static inline int nand_ecc_sw_hamming_calculate(struct nand_device *nand,
+                                               const unsigned char *buf,
+                                               unsigned char *code)
+{
+       return -ENOTSUPP;
+}
+
+static inline int ecc_sw_hamming_correct(unsigned char *buf,
+                                        unsigned char *read_ecc,
+                                        unsigned char *calc_ecc,
+                                        unsigned int step_size, bool sm_order)
+{
+       return -ENOTSUPP;
+}
+
+static inline int nand_ecc_sw_hamming_correct(struct nand_device *nand,
+                                             unsigned char *buf,
+                                             unsigned char *read_ecc,
+                                             unsigned char *calc_ecc)
+{
+       return -ENOTSUPP;
+}
+
+#endif /* CONFIG_MTD_NAND_ECC_SW_HAMMING */
+
 #endif /* __MTD_NAND_ECC_SW_HAMMING_H__ */