diff options
Diffstat (limited to 'drivers/mtd/nand/ecc.c')
| -rw-r--r-- | drivers/mtd/nand/ecc.c | 484 |
1 files changed, 484 insertions, 0 deletions
diff --git a/drivers/mtd/nand/ecc.c b/drivers/mtd/nand/ecc.c new file mode 100644 index 000000000000..4a56e6c0da67 --- /dev/null +++ b/drivers/mtd/nand/ecc.c @@ -0,0 +1,484 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * Generic Error-Correcting Code (ECC) engine + * + * Copyright (C) 2019 Macronix + * Author: + * Miquèl RAYNAL <miquel.raynal@bootlin.com> + * + * + * This file describes the abstraction of any NAND ECC engine. It has been + * designed to fit most cases, including parallel NANDs and SPI-NANDs. + * + * There are three main situations where instantiating this ECC engine makes + * sense: + * - external: The ECC engine is outside the NAND pipeline, typically this + * is a software ECC engine, or an hardware engine that is + * outside the NAND controller pipeline. + * - pipelined: The ECC engine is inside the NAND pipeline, ie. on the + * controller's side. This is the case of most of the raw NAND + * controllers. In the pipeline case, the ECC bytes are + * generated/data corrected on the fly when a page is + * written/read. + * - ondie: The ECC engine is inside the NAND pipeline, on the chip's side. + * Some NAND chips can correct themselves the data. + * + * Besides the initial setup and final cleanups, the interfaces are rather + * simple: + * - prepare: Prepare an I/O request. Enable/disable the ECC engine based on + * the I/O request type. In case of software correction or external + * engine, this step may involve to derive the ECC bytes and place + * them in the OOB area before a write. + * - finish: Finish an I/O request. Correct the data in case of a read + * request and report the number of corrected bits/uncorrectable + * errors. Most likely empty for write operations, unless you have + * hardware specific stuff to do, like shutting down the engine to + * save power. + * + * The I/O request should be enclosed in a prepare()/finish() pair of calls + * and will behave differently depending on the requested I/O type: + * - raw: Correction disabled + * - ecc: Correction enabled + * + * The request direction is impacting the logic as well: + * - read: Load data from the NAND chip + * - write: Store data in the NAND chip + * + * Mixing all this combinations together gives the following behavior. + * Those are just examples, drivers are free to add custom steps in their + * prepare/finish hook. + * + * [external ECC engine] + * - external + prepare + raw + read: do nothing + * - external + finish + raw + read: do nothing + * - external + prepare + raw + write: do nothing + * - external + finish + raw + write: do nothing + * - external + prepare + ecc + read: do nothing + * - external + finish + ecc + read: calculate expected ECC bytes, extract + * ECC bytes from OOB buffer, correct + * and report any bitflip/error + * - external + prepare + ecc + write: calculate ECC bytes and store them at + * the right place in the OOB buffer based + * on the OOB layout + * - external + finish + ecc + write: do nothing + * + * [pipelined ECC engine] + * - pipelined + prepare + raw + read: disable the controller's ECC engine if + * activated + * - pipelined + finish + raw + read: do nothing + * - pipelined + prepare + raw + write: disable the controller's ECC engine if + * activated + * - pipelined + finish + raw + write: do nothing + * - pipelined + prepare + ecc + read: enable the controller's ECC engine if + * deactivated + * - pipelined + finish + ecc + read: check the status, report any + * error/bitflip + * - pipelined + prepare + ecc + write: enable the controller's ECC engine if + * deactivated + * - pipelined + finish + ecc + write: do nothing + * + * [ondie ECC engine] + * - ondie + prepare + raw + read: send commands to disable the on-chip ECC + * engine if activated + * - ondie + finish + raw + read: do nothing + * - ondie + prepare + raw + write: send commands to disable the on-chip ECC + * engine if activated + * - ondie + finish + raw + write: do nothing + * - ondie + prepare + ecc + read: send commands to enable the on-chip ECC + * engine if deactivated + * - ondie + finish + ecc + read: send commands to check the status, report + * any error/bitflip + * - ondie + prepare + ecc + write: send commands to enable the on-chip ECC + * engine if deactivated + * - ondie + finish + ecc + write: do nothing + */ + +#include <linux/module.h> +#include <linux/mtd/nand.h> + +/** + * nand_ecc_init_ctx - Init the ECC engine context + * @nand: the NAND device + * + * On success, the caller is responsible of calling @nand_ecc_cleanup_ctx(). + */ +int nand_ecc_init_ctx(struct nand_device *nand) +{ + if (!nand->ecc.engine->ops->init_ctx) + return 0; + + return nand->ecc.engine->ops->init_ctx(nand); +} +EXPORT_SYMBOL(nand_ecc_init_ctx); + +/** + * nand_ecc_cleanup_ctx - Cleanup the ECC engine context + * @nand: the NAND device + */ +void nand_ecc_cleanup_ctx(struct nand_device *nand) +{ + if (nand->ecc.engine->ops->cleanup_ctx) + nand->ecc.engine->ops->cleanup_ctx(nand); +} +EXPORT_SYMBOL(nand_ecc_cleanup_ctx); + +/** + * nand_ecc_prepare_io_req - Prepare an I/O request + * @nand: the NAND device + * @req: the I/O request + */ +int nand_ecc_prepare_io_req(struct nand_device *nand, + struct nand_page_io_req *req) +{ + if (!nand->ecc.engine->ops->prepare_io_req) + return 0; + + return nand->ecc.engine->ops->prepare_io_req(nand, req); +} +EXPORT_SYMBOL(nand_ecc_prepare_io_req); + +/** + * nand_ecc_finish_io_req - Finish an I/O request + * @nand: the NAND device + * @req: the I/O request + */ +int nand_ecc_finish_io_req(struct nand_device *nand, + struct nand_page_io_req *req) +{ + if (!nand->ecc.engine->ops->finish_io_req) + return 0; + + return nand->ecc.engine->ops->finish_io_req(nand, req); +} +EXPORT_SYMBOL(nand_ecc_finish_io_req); + +/* Define default OOB placement schemes for large and small page devices */ +static int nand_ooblayout_ecc_sp(struct mtd_info *mtd, int section, + struct mtd_oob_region *oobregion) +{ + struct nand_device *nand = mtd_to_nanddev(mtd); + unsigned int total_ecc_bytes = nand->ecc.ctx.total; + + if (section > 1) + return -ERANGE; + + if (!section) { + oobregion->offset = 0; + if (mtd->oobsize == 16) + oobregion->length = 4; + else + oobregion->length = 3; + } else { + if (mtd->oobsize == 8) + return -ERANGE; + + oobregion->offset = 6; + oobregion->length = total_ecc_bytes - 4; + } + + return 0; +} + +static int nand_ooblayout_free_sp(struct mtd_info *mtd, int section, + struct mtd_oob_region *oobregion) +{ + if (section > 1) + return -ERANGE; + + if (mtd->oobsize == 16) { + if (section) + return -ERANGE; + + oobregion->length = 8; + oobregion->offset = 8; + } else { + oobregion->length = 2; + if (!section) + oobregion->offset = 3; + else + oobregion->offset = 6; + } + + return 0; +} + +static const struct mtd_ooblayout_ops nand_ooblayout_sp_ops = { + .ecc = nand_ooblayout_ecc_sp, + .free = nand_ooblayout_free_sp, +}; + +const struct mtd_ooblayout_ops *nand_get_small_page_ooblayout(void) +{ + return &nand_ooblayout_sp_ops; +} +EXPORT_SYMBOL_GPL(nand_get_small_page_ooblayout); + +static int nand_ooblayout_ecc_lp(struct mtd_info *mtd, int section, + struct mtd_oob_region *oobregion) +{ + struct nand_device *nand = mtd_to_nanddev(mtd); + unsigned int total_ecc_bytes = nand->ecc.ctx.total; + + if (section || !total_ecc_bytes) + return -ERANGE; + + oobregion->length = total_ecc_bytes; + oobregion->offset = mtd->oobsize - oobregion->length; + + return 0; +} + +static int nand_ooblayout_free_lp(struct mtd_info *mtd, int section, + struct mtd_oob_region *oobregion) +{ + struct nand_device *nand = mtd_to_nanddev(mtd); + unsigned int total_ecc_bytes = nand->ecc.ctx.total; + + if (section) + return -ERANGE; + + oobregion->length = mtd->oobsize - total_ecc_bytes - 2; + oobregion->offset = 2; + + return 0; +} + +static const struct mtd_ooblayout_ops nand_ooblayout_lp_ops = { + .ecc = nand_ooblayout_ecc_lp, + .free = nand_ooblayout_free_lp, +}; + +const struct mtd_ooblayout_ops *nand_get_large_page_ooblayout(void) +{ + return &nand_ooblayout_lp_ops; +} +EXPORT_SYMBOL_GPL(nand_get_large_page_ooblayout); + +/* + * Support the old "large page" layout used for 1-bit Hamming ECC where ECC + * are placed at a fixed offset. + */ +static int nand_ooblayout_ecc_lp_hamming(struct mtd_info *mtd, int section, + struct mtd_oob_region *oobregion) +{ + struct nand_device *nand = mtd_to_nanddev(mtd); + unsigned int total_ecc_bytes = nand->ecc.ctx.total; + + if (section) + return -ERANGE; + + switch (mtd->oobsize) { + case 64: + oobregion->offset = 40; + break; + case 128: + oobregion->offset = 80; + break; + default: + return -EINVAL; + } + + oobregion->length = total_ecc_bytes; + if (oobregion->offset + oobregion->length > mtd->oobsize) + return -ERANGE; + + return 0; +} + +static int nand_ooblayout_free_lp_hamming(struct mtd_info *mtd, int section, + struct mtd_oob_region *oobregion) +{ + struct nand_device *nand = mtd_to_nanddev(mtd); + unsigned int total_ecc_bytes = nand->ecc.ctx.total; + int ecc_offset = 0; + + if (section < 0 || section > 1) + return -ERANGE; + + switch (mtd->oobsize) { + case 64: + ecc_offset = 40; + break; + case 128: + ecc_offset = 80; + break; + default: + return -EINVAL; + } + + if (section == 0) { + oobregion->offset = 2; + oobregion->length = ecc_offset - 2; + } else { + oobregion->offset = ecc_offset + total_ecc_bytes; + oobregion->length = mtd->oobsize - oobregion->offset; + } + + return 0; +} + +static const struct mtd_ooblayout_ops nand_ooblayout_lp_hamming_ops = { + .ecc = nand_ooblayout_ecc_lp_hamming, + .free = nand_ooblayout_free_lp_hamming, +}; + +const struct mtd_ooblayout_ops *nand_get_large_page_hamming_ooblayout(void) +{ + return &nand_ooblayout_lp_hamming_ops; +} +EXPORT_SYMBOL_GPL(nand_get_large_page_hamming_ooblayout); + +static enum nand_ecc_engine_type +of_get_nand_ecc_engine_type(struct device_node *np) +{ + struct device_node *eng_np; + + if (of_property_read_bool(np, "nand-no-ecc-engine")) + return NAND_ECC_ENGINE_TYPE_NONE; + + if (of_property_read_bool(np, "nand-use-soft-ecc-engine")) + return NAND_ECC_ENGINE_TYPE_SOFT; + + eng_np = of_parse_phandle(np, "nand-ecc-engine", 0); + of_node_put(eng_np); + + if (eng_np) { + if (eng_np == np) + return NAND_ECC_ENGINE_TYPE_ON_DIE; + else + return NAND_ECC_ENGINE_TYPE_ON_HOST; + } + + return NAND_ECC_ENGINE_TYPE_INVALID; +} + +static const char * const nand_ecc_placement[] = { + [NAND_ECC_PLACEMENT_OOB] = "oob", + [NAND_ECC_PLACEMENT_INTERLEAVED] = "interleaved", +}; + +static enum nand_ecc_placement of_get_nand_ecc_placement(struct device_node *np) +{ + enum nand_ecc_placement placement; + const char *pm; + int err; + + err = of_property_read_string(np, "nand-ecc-placement", &pm); + if (!err) { + for (placement = NAND_ECC_PLACEMENT_OOB; + placement < ARRAY_SIZE(nand_ecc_placement); placement++) { + if (!strcasecmp(pm, nand_ecc_placement[placement])) + return placement; + } + } + + return NAND_ECC_PLACEMENT_UNKNOWN; +} + +static const char * const nand_ecc_algos[] = { + [NAND_ECC_ALGO_HAMMING] = "hamming", + [NAND_ECC_ALGO_BCH] = "bch", + [NAND_ECC_ALGO_RS] = "rs", +}; + +static enum nand_ecc_algo of_get_nand_ecc_algo(struct device_node *np) +{ + enum nand_ecc_algo ecc_algo; + const char *pm; + int err; + + err = of_property_read_string(np, "nand-ecc-algo", &pm); + if (!err) { + for (ecc_algo = NAND_ECC_ALGO_HAMMING; + ecc_algo < ARRAY_SIZE(nand_ecc_algos); + ecc_algo++) { + if (!strcasecmp(pm, nand_ecc_algos[ecc_algo])) + return ecc_algo; + } + } + + return NAND_ECC_ALGO_UNKNOWN; +} + +static int of_get_nand_ecc_step_size(struct device_node *np) +{ + int ret; + u32 val; + + ret = of_property_read_u32(np, "nand-ecc-step-size", &val); + return ret ? ret : val; +} + +static int of_get_nand_ecc_strength(struct device_node *np) +{ + int ret; + u32 val; + + ret = of_property_read_u32(np, "nand-ecc-strength", &val); + return ret ? ret : val; +} + +void of_get_nand_ecc_user_config(struct nand_device *nand) +{ + struct device_node *dn = nanddev_get_of_node(nand); + int strength, size; + + nand->ecc.user_conf.engine_type = of_get_nand_ecc_engine_type(dn); + nand->ecc.user_conf.algo = of_get_nand_ecc_algo(dn); + nand->ecc.user_conf.placement = of_get_nand_ecc_placement(dn); + + strength = of_get_nand_ecc_strength(dn); + if (strength >= 0) + nand->ecc.user_conf.strength = strength; + + size = of_get_nand_ecc_step_size(dn); + if (size >= 0) + nand->ecc.user_conf.step_size = size; + + if (of_property_read_bool(dn, "nand-ecc-maximize")) + nand->ecc.user_conf.flags |= NAND_ECC_MAXIMIZE_STRENGTH; +} +EXPORT_SYMBOL(of_get_nand_ecc_user_config); + +/** + * nand_ecc_is_strong_enough - Check if the chip configuration meets the + * datasheet requirements. + * + * @nand: Device to check + * + * If our configuration corrects A bits per B bytes and the minimum + * required correction level is X bits per Y bytes, then we must ensure + * both of the following are true: + * + * (1) A / B >= X / Y + * (2) A >= X + * + * Requirement (1) ensures we can correct for the required bitflip density. + * Requirement (2) ensures we can correct even when all bitflips are clumped + * in the same sector. + */ +bool nand_ecc_is_strong_enough(struct nand_device *nand) +{ + const struct nand_ecc_props *reqs = nanddev_get_ecc_requirements(nand); + const struct nand_ecc_props *conf = nanddev_get_ecc_conf(nand); + struct mtd_info *mtd = nanddev_to_mtd(nand); + int corr, ds_corr; + + if (conf->step_size == 0 || reqs->step_size == 0) + /* Not enough information */ + return true; + + /* + * We get the number of corrected bits per page to compare + * the correction density. + */ + corr = (mtd->writesize * conf->strength) / conf->step_size; + ds_corr = (mtd->writesize * reqs->strength) / reqs->step_size; + + return corr >= ds_corr && conf->strength >= reqs->strength; +} +EXPORT_SYMBOL(nand_ecc_is_strong_enough); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Miquel Raynal <miquel.raynal@bootlin.com>"); +MODULE_DESCRIPTION("Generic ECC engine"); |