diff options
Diffstat (limited to 'drivers/mtd/nand/ecc-realtek.c')
| -rw-r--r-- | drivers/mtd/nand/ecc-realtek.c | 464 |
1 files changed, 464 insertions, 0 deletions
diff --git a/drivers/mtd/nand/ecc-realtek.c b/drivers/mtd/nand/ecc-realtek.c new file mode 100644 index 000000000000..7d718934c909 --- /dev/null +++ b/drivers/mtd/nand/ecc-realtek.c @@ -0,0 +1,464 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Support for Realtek hardware ECC engine in RTL93xx SoCs + */ + +#include <linux/bitfield.h> +#include <linux/dma-mapping.h> +#include <linux/mtd/nand.h> +#include <linux/mutex.h> +#include <linux/platform_device.h> +#include <linux/regmap.h> + +/* + * The Realtek ECC engine has two operation modes. + * + * - BCH6 : Generate 10 ECC bytes from 512 data bytes plus 6 free bytes + * - BCH12 : Generate 20 ECC bytes from 512 data bytes plus 6 free bytes + * + * It can run for arbitrary NAND flash chips with different block and OOB sizes. Currently there + * are only two known devices in the wild that have NAND flash and make use of this ECC engine + * (Linksys LGS328C & LGS352C). To keep compatibility with vendor firmware, new modes can only + * be added when new data layouts have been analyzed. For now allow BCH6 on flash with 2048 byte + * blocks and 64 bytes oob. + * + * This driver aligns with kernel ECC naming conventions. Neverthless a short notice on the + * Realtek naming conventions for the different structures in the OOB area. + * + * - BBI : Bad block indicator. The first two bytes of OOB. Protected by ECC! + * - tag : 6 User/free bytes. First tag "contains" 2 bytes BBI. Protected by ECC! + * - syndrome : ECC/parity bytes + * + * Altogether this gives currently the following block layout. + * + * +------+------+------+------+-----+------+------+------+------+-----+-----+-----+-----+ + * | 512 | 512 | 512 | 512 | 2 | 4 | 6 | 6 | 6 | 10 | 10 | 10 | 10 | + * +------+------+------+------+-----+------+------+------+------+-----+-----+-----+-----+ + * | data | data | data | data | BBI | free | free | free | free | ECC | ECC | ECC | ECC | + * +------+------+------+------+-----+------+------+------+------+-----+-----+-----+-----+ + */ + +#define RTL_ECC_ALLOWED_PAGE_SIZE 2048 +#define RTL_ECC_ALLOWED_OOB_SIZE 64 +#define RTL_ECC_ALLOWED_STRENGTH 6 + +#define RTL_ECC_BLOCK_SIZE 512 +#define RTL_ECC_FREE_SIZE 6 +#define RTL_ECC_PARITY_SIZE_BCH6 10 +#define RTL_ECC_PARITY_SIZE_BCH12 20 + +/* + * The engine is fed with two DMA regions. One for data (always 512 bytes) and one for free bytes + * and parity (either 16 bytes for BCH6 or 26 bytes for BCH12). Start and length of each must be + * aligned to a multiple of 4. + */ + +#define RTL_ECC_DMA_FREE_PARITY_SIZE ALIGN(RTL_ECC_FREE_SIZE + RTL_ECC_PARITY_SIZE_BCH12, 4) +#define RTL_ECC_DMA_SIZE (RTL_ECC_BLOCK_SIZE + RTL_ECC_DMA_FREE_PARITY_SIZE) + +#define RTL_ECC_CFG 0x00 +#define RTL_ECC_BCH6 0 +#define RTL_ECC_BCH12 BIT(28) +#define RTL_ECC_DMA_PRECISE BIT(12) +#define RTL_ECC_BURST_128 GENMASK(1, 0) +#define RTL_ECC_DMA_TRIGGER 0x08 +#define RTL_ECC_OP_DECODE 0 +#define RTL_ECC_OP_ENCODE BIT(0) +#define RTL_ECC_DMA_START 0x0c +#define RTL_ECC_DMA_TAG 0x10 +#define RTL_ECC_STATUS 0x14 +#define RTL_ECC_CORR_COUNT GENMASK(19, 12) +#define RTL_ECC_RESULT BIT(8) +#define RTL_ECC_ALL_ONE BIT(4) +#define RTL_ECC_OP_STATUS BIT(0) + +struct rtl_ecc_engine { + struct device *dev; + struct nand_ecc_engine engine; + struct mutex lock; + char *buf; + dma_addr_t buf_dma; + struct regmap *regmap; +}; + +struct rtl_ecc_ctx { + struct rtl_ecc_engine * rtlc; + struct nand_ecc_req_tweak_ctx req_ctx; + int steps; + int bch_mode; + int strength; + int parity_size; +}; + +static const struct regmap_config rtl_ecc_regmap_config = { + .reg_bits = 32, + .val_bits = 32, + .reg_stride = 4, +}; + +static inline void *nand_to_ctx(struct nand_device *nand) +{ + return nand->ecc.ctx.priv; +} + +static inline struct rtl_ecc_engine *nand_to_rtlc(struct nand_device *nand) +{ + struct nand_ecc_engine *eng = nand->ecc.engine; + + return container_of(eng, struct rtl_ecc_engine, engine); +} + +static int rtl_ecc_ooblayout_ecc(struct mtd_info *mtd, int section, + struct mtd_oob_region *oobregion) +{ + struct nand_device *nand = mtd_to_nanddev(mtd); + struct rtl_ecc_ctx *ctx = nand_to_ctx(nand); + + if (section < 0 || section >= ctx->steps) + return -ERANGE; + + oobregion->offset = ctx->steps * RTL_ECC_FREE_SIZE + section * ctx->parity_size; + oobregion->length = ctx->parity_size; + + return 0; +} + +static int rtl_ecc_ooblayout_free(struct mtd_info *mtd, int section, + struct mtd_oob_region *oobregion) +{ + struct nand_device *nand = mtd_to_nanddev(mtd); + struct rtl_ecc_ctx *ctx = nand_to_ctx(nand); + int bbm; + + if (section < 0 || section >= ctx->steps) + return -ERANGE; + + /* reserve 2 BBM bytes in first block */ + bbm = section ? 0 : 2; + oobregion->offset = section * RTL_ECC_FREE_SIZE + bbm; + oobregion->length = RTL_ECC_FREE_SIZE - bbm; + + return 0; +} + +static const struct mtd_ooblayout_ops rtl_ecc_ooblayout_ops = { + .ecc = rtl_ecc_ooblayout_ecc, + .free = rtl_ecc_ooblayout_free, +}; + +static void rtl_ecc_kick_engine(struct rtl_ecc_ctx *ctx, int operation) +{ + struct rtl_ecc_engine *rtlc = ctx->rtlc; + + regmap_write(rtlc->regmap, RTL_ECC_CFG, + ctx->bch_mode | RTL_ECC_BURST_128 | RTL_ECC_DMA_PRECISE); + + regmap_write(rtlc->regmap, RTL_ECC_DMA_START, rtlc->buf_dma); + regmap_write(rtlc->regmap, RTL_ECC_DMA_TAG, rtlc->buf_dma + RTL_ECC_BLOCK_SIZE); + regmap_write(rtlc->regmap, RTL_ECC_DMA_TRIGGER, operation); +} + +static int rtl_ecc_wait_for_engine(struct rtl_ecc_ctx *ctx) +{ + struct rtl_ecc_engine *rtlc = ctx->rtlc; + int ret, status, bitflips; + bool all_one; + + /* + * The ECC engine needs 6-8 us to encode/decode a BCH6 syndrome for 512 bytes of data + * and 6 free bytes. In case the NAND area has been erased and all data and oob is + * set to 0xff, decoding takes 30us (reason unknown). Although the engine can trigger + * interrupts when finished, use active polling for now. 12 us maximum wait time has + * proven to be a good tradeoff between performance and overhead. + */ + + ret = regmap_read_poll_timeout(rtlc->regmap, RTL_ECC_STATUS, status, + !(status & RTL_ECC_OP_STATUS), 12, 1000000); + if (ret) + return ret; + + ret = FIELD_GET(RTL_ECC_RESULT, status); + all_one = FIELD_GET(RTL_ECC_ALL_ONE, status); + bitflips = FIELD_GET(RTL_ECC_CORR_COUNT, status); + + /* For erased blocks (all bits one) error status can be ignored */ + if (all_one) + ret = 0; + + return ret ? -EBADMSG : bitflips; +} + +static int rtl_ecc_run_engine(struct rtl_ecc_ctx *ctx, char *data, char *free, + char *parity, int operation) +{ + struct rtl_ecc_engine *rtlc = ctx->rtlc; + char *buf_parity = rtlc->buf + RTL_ECC_BLOCK_SIZE + RTL_ECC_FREE_SIZE; + char *buf_free = rtlc->buf + RTL_ECC_BLOCK_SIZE; + char *buf_data = rtlc->buf; + int ret; + + mutex_lock(&rtlc->lock); + + memcpy(buf_data, data, RTL_ECC_BLOCK_SIZE); + memcpy(buf_free, free, RTL_ECC_FREE_SIZE); + memcpy(buf_parity, parity, ctx->parity_size); + + dma_sync_single_for_device(rtlc->dev, rtlc->buf_dma, RTL_ECC_DMA_SIZE, DMA_TO_DEVICE); + rtl_ecc_kick_engine(ctx, operation); + ret = rtl_ecc_wait_for_engine(ctx); + dma_sync_single_for_cpu(rtlc->dev, rtlc->buf_dma, RTL_ECC_DMA_SIZE, DMA_FROM_DEVICE); + + if (ret >= 0) { + memcpy(data, buf_data, RTL_ECC_BLOCK_SIZE); + memcpy(free, buf_free, RTL_ECC_FREE_SIZE); + memcpy(parity, buf_parity, ctx->parity_size); + } + + mutex_unlock(&rtlc->lock); + + return ret; +} + +static int rtl_ecc_prepare_io_req(struct nand_device *nand, struct nand_page_io_req *req) +{ + struct rtl_ecc_engine *rtlc = nand_to_rtlc(nand); + struct rtl_ecc_ctx *ctx = nand_to_ctx(nand); + char *data, *free, *parity; + int ret = 0; + + if (req->mode == MTD_OPS_RAW) + return 0; + + nand_ecc_tweak_req(&ctx->req_ctx, req); + + if (req->type == NAND_PAGE_READ) + return 0; + + free = req->oobbuf.in; + data = req->databuf.in; + parity = req->oobbuf.in + ctx->steps * RTL_ECC_FREE_SIZE; + + for (int i = 0; i < ctx->steps; i++) { + ret |= rtl_ecc_run_engine(ctx, data, free, parity, RTL_ECC_OP_ENCODE); + + free += RTL_ECC_FREE_SIZE; + data += RTL_ECC_BLOCK_SIZE; + parity += ctx->parity_size; + } + + if (unlikely(ret)) + dev_dbg(rtlc->dev, "ECC calculation failed\n"); + + return ret ? -EBADMSG : 0; +} + +static int rtl_ecc_finish_io_req(struct nand_device *nand, struct nand_page_io_req *req) +{ + struct rtl_ecc_engine *rtlc = nand_to_rtlc(nand); + struct rtl_ecc_ctx *ctx = nand_to_ctx(nand); + struct mtd_info *mtd = nanddev_to_mtd(nand); + char *data, *free, *parity; + bool failure = false; + int bitflips = 0; + + if (req->mode == MTD_OPS_RAW) + return 0; + + if (req->type == NAND_PAGE_WRITE) { + nand_ecc_restore_req(&ctx->req_ctx, req); + return 0; + } + + free = req->oobbuf.in; + data = req->databuf.in; + parity = req->oobbuf.in + ctx->steps * RTL_ECC_FREE_SIZE; + + for (int i = 0 ; i < ctx->steps; i++) { + int ret = rtl_ecc_run_engine(ctx, data, free, parity, RTL_ECC_OP_DECODE); + + if (unlikely(ret < 0)) + /* ECC totally fails for bitflips in erased blocks */ + ret = nand_check_erased_ecc_chunk(data, RTL_ECC_BLOCK_SIZE, + parity, ctx->parity_size, + free, RTL_ECC_FREE_SIZE, + ctx->strength); + if (unlikely(ret < 0)) { + failure = true; + mtd->ecc_stats.failed++; + } else { + mtd->ecc_stats.corrected += ret; + bitflips = max_t(unsigned int, bitflips, ret); + } + + free += RTL_ECC_FREE_SIZE; + data += RTL_ECC_BLOCK_SIZE; + parity += ctx->parity_size; + } + + nand_ecc_restore_req(&ctx->req_ctx, req); + + if (unlikely(failure)) + dev_dbg(rtlc->dev, "ECC correction failed\n"); + else if (unlikely(bitflips > 2)) + dev_dbg(rtlc->dev, "%d bitflips detected\n", bitflips); + + return failure ? -EBADMSG : bitflips; +} + +static int rtl_ecc_check_support(struct nand_device *nand) +{ + struct mtd_info *mtd = nanddev_to_mtd(nand); + struct device *dev = nand->ecc.engine->dev; + + if (mtd->oobsize != RTL_ECC_ALLOWED_OOB_SIZE || + mtd->writesize != RTL_ECC_ALLOWED_PAGE_SIZE) { + dev_err(dev, "only flash geometry data=%d, oob=%d supported\n", + RTL_ECC_ALLOWED_PAGE_SIZE, RTL_ECC_ALLOWED_OOB_SIZE); + return -EINVAL; + } + + if (nand->ecc.user_conf.algo != NAND_ECC_ALGO_BCH || + nand->ecc.user_conf.strength != RTL_ECC_ALLOWED_STRENGTH || + nand->ecc.user_conf.placement != NAND_ECC_PLACEMENT_OOB || + nand->ecc.user_conf.step_size != RTL_ECC_BLOCK_SIZE) { + dev_err(dev, "only algo=bch, strength=%d, placement=oob, step=%d supported\n", + RTL_ECC_ALLOWED_STRENGTH, RTL_ECC_BLOCK_SIZE); + return -EINVAL; + } + + return 0; +} + +static int rtl_ecc_init_ctx(struct nand_device *nand) +{ + struct nand_ecc_props *conf = &nand->ecc.ctx.conf; + struct rtl_ecc_engine *rtlc = nand_to_rtlc(nand); + struct mtd_info *mtd = nanddev_to_mtd(nand); + int strength = nand->ecc.user_conf.strength; + struct device *dev = nand->ecc.engine->dev; + struct rtl_ecc_ctx *ctx; + int ret; + + ret = rtl_ecc_check_support(nand); + if (ret) + return ret; + + ctx = devm_kzalloc(dev, sizeof(*ctx), GFP_KERNEL); + if (!ctx) + return -ENOMEM; + + nand->ecc.ctx.priv = ctx; + mtd_set_ooblayout(mtd, &rtl_ecc_ooblayout_ops); + + conf->algo = NAND_ECC_ALGO_BCH; + conf->strength = strength; + conf->step_size = RTL_ECC_BLOCK_SIZE; + conf->engine_type = NAND_ECC_ENGINE_TYPE_ON_HOST; + + ctx->rtlc = rtlc; + ctx->steps = mtd->writesize / RTL_ECC_BLOCK_SIZE; + ctx->strength = strength; + ctx->bch_mode = strength == 6 ? RTL_ECC_BCH6 : RTL_ECC_BCH12; + ctx->parity_size = strength == 6 ? RTL_ECC_PARITY_SIZE_BCH6 : RTL_ECC_PARITY_SIZE_BCH12; + + ret = nand_ecc_init_req_tweaking(&ctx->req_ctx, nand); + if (ret) + return ret; + + dev_dbg(dev, "using bch%d with geometry data=%dx%d, free=%dx6, parity=%dx%d", + conf->strength, ctx->steps, conf->step_size, + ctx->steps, ctx->steps, ctx->parity_size); + + return 0; +} + +static void rtl_ecc_cleanup_ctx(struct nand_device *nand) +{ + struct rtl_ecc_ctx *ctx = nand_to_ctx(nand); + + if (ctx) + nand_ecc_cleanup_req_tweaking(&ctx->req_ctx); +} + +static struct nand_ecc_engine_ops rtl_ecc_engine_ops = { + .init_ctx = rtl_ecc_init_ctx, + .cleanup_ctx = rtl_ecc_cleanup_ctx, + .prepare_io_req = rtl_ecc_prepare_io_req, + .finish_io_req = rtl_ecc_finish_io_req, +}; + +static int rtl_ecc_probe(struct platform_device *pdev) +{ + struct device *dev = &pdev->dev; + struct rtl_ecc_engine *rtlc; + void __iomem *base; + int ret; + + rtlc = devm_kzalloc(dev, sizeof(*rtlc), GFP_KERNEL); + if (!rtlc) + return -ENOMEM; + + base = devm_platform_ioremap_resource(pdev, 0); + if (IS_ERR(base)) + return PTR_ERR(base); + + ret = devm_mutex_init(dev, &rtlc->lock); + if (ret) + return ret; + + rtlc->regmap = devm_regmap_init_mmio(dev, base, &rtl_ecc_regmap_config); + if (IS_ERR(rtlc->regmap)) + return PTR_ERR(rtlc->regmap); + + /* + * Focus on simplicity and use a preallocated DMA buffer for data exchange with the + * engine. For now make it a noncoherent memory model as invalidating/flushing caches + * is faster than reading/writing uncached memory on the known architectures. + */ + + rtlc->buf = dma_alloc_noncoherent(dev, RTL_ECC_DMA_SIZE, &rtlc->buf_dma, + DMA_BIDIRECTIONAL, GFP_KERNEL); + if (IS_ERR(rtlc->buf)) + return PTR_ERR(rtlc->buf); + + rtlc->dev = dev; + rtlc->engine.dev = dev; + rtlc->engine.ops = &rtl_ecc_engine_ops; + rtlc->engine.integration = NAND_ECC_ENGINE_INTEGRATION_EXTERNAL; + + nand_ecc_register_on_host_hw_engine(&rtlc->engine); + + platform_set_drvdata(pdev, rtlc); + + return 0; +} + +static void rtl_ecc_remove(struct platform_device *pdev) +{ + struct rtl_ecc_engine *rtlc = platform_get_drvdata(pdev); + + nand_ecc_unregister_on_host_hw_engine(&rtlc->engine); + dma_free_noncoherent(rtlc->dev, RTL_ECC_DMA_SIZE, rtlc->buf, rtlc->buf_dma, + DMA_BIDIRECTIONAL); +} + +static const struct of_device_id rtl_ecc_of_ids[] = { + { + .compatible = "realtek,rtl9301-ecc", + }, + { /* sentinel */ }, +}; + +static struct platform_driver rtl_ecc_driver = { + .driver = { + .name = "rtl-nand-ecc-engine", + .of_match_table = rtl_ecc_of_ids, + }, + .probe = rtl_ecc_probe, + .remove = rtl_ecc_remove, +}; +module_platform_driver(rtl_ecc_driver); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Markus Stockhausen <markus.stockhausen@gmx.de>"); +MODULE_DESCRIPTION("Realtek NAND hardware ECC controller"); |