Re: [PATCH] mtd: nand: ecc-mtk: add external ecc engine support
From: AngeloGioacchino Del Regno
Date: Tue May 03 2022 - 09:54:27 EST
Il 30/04/22 18:40, Chuanhong Guo ha scritto:
This adds support for using ecc-mtk as an external ECC engine.
The implemented OOB layout follows the convention to put all ECC data
at the end of OOB. As a result, the data layout is incompatible with
MTK NFI piplined ECC mode.
Signed-off-by: Chuanhong Guo <gch981213@xxxxxxxxx>
---
drivers/mtd/nand/ecc-mtk.c | 335 ++++++++++++++++++++++++++++++++++++-
1 file changed, 331 insertions(+), 4 deletions(-)
diff --git a/drivers/mtd/nand/ecc-mtk.c b/drivers/mtd/nand/ecc-mtk.c
index 9f9b201fe706..998276ada671 100644
--- a/drivers/mtd/nand/ecc-mtk.c
+++ b/drivers/mtd/nand/ecc-mtk.c
@@ -15,6 +15,7 @@
#include <linux/of.h>
#include <linux/of_platform.h>
#include <linux/mutex.h>
+#include <linux/mtd/nand.h>
#include <linux/mtd/nand-ecc-mtk.h>
#define ECC_IDLE_MASK BIT(0)
@@ -26,12 +27,14 @@
#define ECC_ENCCON (0x00)
#define ECC_ENCCNFG (0x04)
#define ECC_MS_SHIFT (16)
+#define ECC_MAX_MS (8191)
#define ECC_ENCDIADDR (0x08)
#define ECC_ENCIDLE (0x0C)
#define ECC_DECCON (0x100)
#define ECC_DECCNFG (0x104)
#define DEC_EMPTY_EN BIT(31)
#define DEC_CNFG_CORRECT (0x3 << 12)
+#define ECC_DECDIADDR (0x108)
#define ECC_DECIDLE (0x10C)
#define ECC_DECENUM0 (0x114)
@@ -59,11 +62,23 @@ struct mtk_ecc {
struct completion done;
struct mutex lock;
+ struct nand_ecc_engine ecc_eng;
u32 sectors;
+ u32 refcnt;
Please always use signed values for refcounts.
u8 *eccdata;
};
+struct mtk_ecc_host_ctx {
+ struct mtk_ecc_config cfg;
+ struct nand_ecc_req_tweak_ctx req_ctx;
+ u8 *buf;
+ dma_addr_t buf_dma;
+ u32 free_len;
+ u32 parity_len;
+ u32 steps;
+};
+
/* ecc strength that each IP supports */
static const u8 ecc_strength_mt2701[] = {
4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 28, 32, 36,
@@ -75,6 +90,8 @@ static const u8 ecc_strength_mt2712[] = {
40, 44, 48, 52, 56, 60, 68, 72, 80
};
+static const u8 ecc_strength_mt7621[] = { 4 };
Please remove this one.
+
static const u8 ecc_strength_mt7622[] = {
4, 6, 8, 10, 12
};
@@ -115,6 +132,13 @@ static int mt7622_ecc_regs[] = {
[ECC_DECIRQ_STA] = 0x144,
};
..snip..
@@ -239,8 +268,14 @@ EXPORT_SYMBOL(mtk_ecc_get_stats);
void mtk_ecc_release(struct mtk_ecc *ecc)
{
- clk_disable_unprepare(ecc->clk);
- put_device(ecc->dev);
+ mutex_lock(&ecc->lock);
+
+ ecc->refcnt--;
+ if (!ecc->refcnt) {
For the sake of readability, be explicit here.
if (ecc->refcnt == 0)
...also, for safety (since we're talking about data here) it may be worth to add a
WARN((ecc->refcnt < 0), "sensible warning message here");
+ clk_disable_unprepare(ecc->clk);
+ put_device(ecc->dev);
+ }
+ mutex_unlock(&ecc->lock);
}
EXPORT_SYMBOL(mtk_ecc_release);
+
+static int mtk_ecc_host_init_ctx(struct nand_device *nand)
+{
+ struct mtk_ecc *ecc = nand_to_mtk_ecc(nand);
+ struct nand_ecc_props *conf = &nand->ecc.ctx.conf;
+ struct nand_ecc_props *reqs = &nand->ecc.requirements;
+ struct nand_ecc_props *user = &nand->ecc.user_conf;
+ struct mtd_info *mtd = nanddev_to_mtd(nand);
+ const u8 *ecc_strength = ecc->caps->ecc_strength;
struct mtk_ecc_host_ctx *ctx; belongs here.
+ int step_size = 0, strength = 0;
+ int ret = 0;
+ struct mtk_ecc_host_ctx *ctx;
...not here.
+ int steps, parity_len;
+ int i;
+ u32 parity_bits;
+
..snip..
+
+ dev_info(ecc->dev, "OOB: free: %u bytes, ECC: %u bytes", ctx->free_len,
+ ctx->parity_len * ctx->steps);
+ dev_info(ecc->dev, "ECC strength: %d bits per %d bytes\n", strength,
+ step_size);
I'm not sure that this should really be a dev_info(), or at least not both.. as
I don't think that this is that much informative anyway.
I'd go for dev_dbg() instead.
+ return 0;
+free_buf:
+ dma_free_coherent(ecc->dev, step_size + parity_len, ctx->buf,
+ ctx->buf_dma);
+free_ctx:
+ kfree(ctx);
+ return ret;
+}
+
..snip..
+static int mtk_ecc_host_prepare_io_req(struct nand_device *nand,
+ struct nand_page_io_req *req)
+{
+ struct mtk_ecc *ecc = nand_to_mtk_ecc(nand);
+ struct mtd_info *mtd = nanddev_to_mtd(nand);
+ struct mtk_ecc_host_ctx *ctx = nand_to_ecc_ctx(nand);
+ int ret, step;
+
+ if (req->mode == MTD_OPS_RAW)
+ return 0;
+
+ nand_ecc_tweak_req(&ctx->req_ctx, req);
+
+ if (req->type == NAND_PAGE_READ)
+ return 0;
+
+ ctx->cfg.op = ECC_ENCODE;
+
+ for (step = 0; step < ctx->steps; step++) {
+ ctx->cfg.addr = dma_map_single(
+ ecc->dev, (u8 *)req->databuf.out + step * ctx->cfg.len,
+ ctx->cfg.len, DMA_TO_DEVICE);
+ ret = dma_mapping_error(ecc->dev, ctx->cfg.addr);
+ if (ret) {
+ dev_err(ecc->dev, "DMA mapping failed.\n");
+ return ret;
+ }
+ ret = mtk_ecc_enable(ecc, &ctx->cfg);
+ if (ret) {
+ dma_unmap_single(ecc->dev, ctx->cfg.addr, ctx->cfg.len,
+ DMA_TO_DEVICE);
+ return ret;
+ }
+
+ ret = mtk_ecc_wait_done(ecc, ECC_ENCODE);
+ if (ret) {
+ mtk_ecc_disable(ecc);
+ dma_unmap_single(ecc->dev, ctx->cfg.addr, ctx->cfg.len,
+ DMA_TO_DEVICE);
+ return ret;
+ }
+
+ mtk_ecc_wait_idle(ecc, ECC_ENCODE);
+ dma_unmap_single(ecc->dev, ctx->cfg.addr, ctx->cfg.len,
+ DMA_TO_DEVICE);
+ __ioread32_copy(ecc->eccdata,
+ ecc->regs + ecc->caps->ecc_regs[ECC_ENCPAR00],
+ round_up(ctx->parity_len, 4));
+ mtd_ooblayout_set_eccbytes(mtd, ecc->eccdata,
+ (void *)req->oobbuf.out,
+ ctx->parity_len * step,
+ ctx->parity_len);
+ mtk_ecc_disable(ecc);
+ }
+
+ return ret;
You have addressed all of the error conditions, so return 0 here.
+}
+
+static int mtk_ecc_host_finish_io_req(struct nand_device *nand,
+ struct nand_page_io_req *req)
+{
+ struct mtk_ecc *ecc = nand_to_mtk_ecc(nand);
+ struct mtd_info *mtd = nanddev_to_mtd(nand);
+ struct mtk_ecc_host_ctx *ctx = nand_to_ecc_ctx(nand);
+ u32 bitflips = 0, failed = 0;
+ int ret, step, i;
+ u32 err;
It would be more appropriate to call this variable "val" or "regval".
Also, please reorder the variables, you can do it by name...
struct mtk_ecc_host_ctx *ctx = nand_to_ecc_ctx(nand);
struct mtk_ecc *ecc = nand_to_mtk_ecc(nand);
struct mtd_info *mtd = nanddev_to_mtd(nand);
u32 bitflips = 0, failed = 0, regval;
int ret, step, i;
Please also do the same for the other instances of that.
+
+ /* Nothing to do for a raw operation */
+ if (req->mode == MTD_OPS_RAW)
+ return 0;
+
+ /* This engine does not provide BBM/free OOB bytes protection */
+ if (!req->datalen)
+ return 0;
+
+ /* No more preparation for page write */
+ if (req->type == NAND_PAGE_WRITE) {
+ nand_ecc_restore_req(&ctx->req_ctx, req);
+ return 0;
+ }
+
+ ctx->cfg.op = ECC_DECODE;
+ ctx->cfg.addr = ctx->buf_dma;
+
+ for (step = 0; step < ctx->steps; step++) {
+ memcpy(ctx->buf, req->databuf.in + step * ctx->cfg.len,
+ ctx->cfg.len);
+ mtd_ooblayout_get_eccbytes(mtd, ctx->buf + ctx->cfg.len,
+ req->oobbuf.in,
+ ctx->parity_len * step,
+ ctx->parity_len);
+
+ ret = mtk_ecc_enable(ecc, &ctx->cfg);
+ if (ret)
+ break;
+
+ ret = mtk_ecc_wait_done(ecc, ECC_DECODE);
+ if (ret)
I think that you forgot to revert the enablement here; translation:
you probably forgot to call mtk_ecc_disable(ecc).
Or is there any particular and valid reason to not do that here?
If there is, you should add a comment explaining why.
+ break;
+
+ mtk_ecc_wait_idle(ecc, ECC_DECODE);
+
+ memcpy(req->databuf.in + step * ctx->cfg.len, ctx->buf,
+ ctx->cfg.len);
You can avoid breaking this line, as this results in 87 cols, which is fine.
Same for the other memcpy before that one, and all other instances.
+ mtd_ooblayout_set_eccbytes(mtd, ctx->buf + ctx->cfg.len,
+ req->oobbuf.in,
+ ctx->parity_len * step,
+ ctx->parity_len);
+ err = readl(ecc->regs + ECC_DECENUM0);
+ err &= ecc->caps->err_mask;
+ if (err == ecc->caps->err_mask) {
+ // skip empty page
C-style comments please. /* */
Regards,
Angelo