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Subject[PATCH 13/18] mtd: nand: mxic-ecc: Support SPI pipelined mode
Date
Introduce the support for another possible configuration: the ECC
engine may work as DMA master (pipelined) and move itself the data
to/from the NAND chip into the buffer, applying the necessary
corrections/computations on the fly.

This driver offers an ECC engine implementation that must be
instatiated from a SPI controller driver.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
drivers/mtd/nand/ecc-mxic.c | 148 +++++++++++++++++++++++++++++-
include/linux/mtd/nand-ecc-mxic.h | 36 ++++++++
2 files changed, 181 insertions(+), 3 deletions(-)
create mode 100644 include/linux/mtd/nand-ecc-mxic.h

diff --git a/drivers/mtd/nand/ecc-mxic.c b/drivers/mtd/nand/ecc-mxic.c
index d9b251ab9201..555ba7f19027 100644
--- a/drivers/mtd/nand/ecc-mxic.c
+++ b/drivers/mtd/nand/ecc-mxic.c
@@ -39,7 +39,9 @@
#define INTRPT_SIG_EN 0x0C
/* Host Controller Configuration */
#define HC_CONFIG 0x10
+#define DEV2MEM 0 /* TRANS_TYP_DMA in the spec */
#define MEM2MEM BIT(4) /* TRANS_TYP_IO in the spec */
+#define MAPPING BIT(5) /* TRANS_TYP_MAPPING in the spec */
#define ECC_PACKED 0 /* LAYOUT_TYP_INTEGRATED in the spec */
#define ECC_INTERLEAVED BIT(2) /* LAYOUT_TYP_DISTRIBUTED in the spec */
#define BURST_TYP_FIXED 0
@@ -101,6 +103,7 @@ struct mxic_ecc_engine {
u8 *oobwithstat;
struct scatterlist sg[2];
struct nand_page_io_req *req;
+ unsigned int pageoffs;
};

static int mxic_ecc_ooblayout_ecc(struct mtd_info *mtd, int section,
@@ -188,6 +191,31 @@ static irqreturn_t mxic_ecc_isr(int irq, void *dev_id)
return IRQ_HANDLED;
}

+static struct device *mxic_ecc_get_engine_dev(struct device *dev)
+{
+ struct platform_device *eccpdev;
+ struct device_node *np;
+
+ /*
+ * If the device node contains this property, it means the device does
+ * not represent the actual ECC engine.
+ */
+ np = of_parse_phandle(dev->of_node, "nand-ecc-engine", 0);
+ if (!np)
+ return dev;
+
+ eccpdev = of_find_device_by_node(np);
+ if (!eccpdev) {
+ of_node_put(np);
+ return NULL;
+ }
+
+ platform_device_put(eccpdev);
+ of_node_put(np);
+
+ return &eccpdev->dev;
+}
+
static int mxic_ecc_init_ctx(struct nand_device *nand, struct device *dev)
{
struct platform_device *pdev = to_platform_device(dev);
@@ -379,6 +407,41 @@ static int mxic_ecc_init_ctx_external(struct nand_device *nand)
return 0;
}

+static int mxic_ecc_init_ctx_pipelined(struct nand_device *nand)
+{
+ struct mxic_ecc_engine *eng;
+ struct device *dev;
+ int ret;
+
+ /*
+ * In the case of a pipelined engine, the device registering the ECC
+ * engine is not the actual ECC engine device but the host controller.
+ */
+ dev = mxic_ecc_get_engine_dev(nand->ecc.engine->dev);
+ if (!dev)
+ return -EINVAL;
+
+ dev_info(dev, "Macronix ECC engine in pipelined/mapping mode\n");
+
+ ret = mxic_ecc_init_ctx(nand, dev);
+ if (ret)
+ return ret;
+
+ eng = nand->ecc.ctx.priv;
+
+ /* All steps should be handled in one go directly by the internal DMA */
+ writel(eng->steps, eng->regs + CHUNK_CNT);
+
+ /*
+ * Interleaved ECC scheme cannot be used otherwise factory bad block
+ * markers would be lost. A packed layout is mandatory.
+ */
+ writel(BURST_TYP_INCREASING | ECC_PACKED | MAPPING,
+ eng->regs + HC_CONFIG);
+
+ return 0;
+}
+
static void mxic_ecc_cleanup_ctx(struct nand_device *nand)
{
struct mxic_ecc_engine *eng = nand->ecc.ctx.priv;
@@ -414,18 +477,22 @@ static int mxic_ecc_data_xfer_wait_for_completion(struct mxic_ecc_engine *eng)
return 0;
}

-static int mxic_ecc_process_data(struct mxic_ecc_engine *eng)
+int mxic_ecc_process_data(struct mxic_ecc_engine *eng, dma_addr_t dirmap)
{
/* Retrieve the direction */
unsigned int dir = (eng->req->type == NAND_PAGE_READ) ?
READ_NAND : WRITE_NAND;

+ if (dirmap)
+ writel(dirmap, eng->regs + HC_SLV_ADDR);
+
/* Trigger processing */
writel(SDMA_STRT | dir, eng->regs + SDMA_CTRL);

/* Wait for completion */
return mxic_ecc_data_xfer_wait_for_completion(eng);
}
+EXPORT_SYMBOL_GPL(mxic_ecc_process_data);

static void mxic_ecc_extract_status_bytes(struct mxic_ecc_engine *eng, u8 *buf)
{
@@ -528,7 +595,7 @@ static int mxic_ecc_prepare_io_req_external(struct nand_device *nand,
eng->regs + SDMA_MAIN_ADDR);
writel(sg_dma_address(&eng->sg[1]) + (step * (eng->oob_step_sz + STAT_BYTES)),
eng->regs + SDMA_SPARE_ADDR);
- ret = mxic_ecc_process_data(eng);
+ ret = mxic_ecc_process_data(eng, 0);
if (ret)
break;
}
@@ -582,7 +649,7 @@ static int mxic_ecc_finish_io_req_external(struct nand_device *nand,
eng->regs + SDMA_MAIN_ADDR);
writel(sg_dma_address(&eng->sg[1]) + (step * (eng->oob_step_sz + STAT_BYTES)),
eng->regs + SDMA_SPARE_ADDR);
- ret = mxic_ecc_process_data(eng);
+ ret = mxic_ecc_process_data(eng, 0);
if (ret)
break;
}
@@ -600,6 +667,64 @@ static int mxic_ecc_finish_io_req_external(struct nand_device *nand,
return mxic_ecc_count_biterrs(eng, mtd);
}

+/* Pipelined ECC engine helpers */
+static int mxic_ecc_prepare_io_req_pipelined(struct nand_device *nand,
+ struct nand_page_io_req *req)
+{
+ struct mxic_ecc_engine *eng = nand->ecc.ctx.priv;
+ int nents;
+
+ if (req->mode == MTD_OPS_RAW)
+ return 0;
+
+ nand_ecc_tweak_req(&eng->req_ctx, req);
+ eng->req = req;
+
+ /* Copy the OOB buffer and add room for the ECC engine status bytes */
+ mxic_ecc_add_room_in_oobbuf(eng, eng->oobwithstat, eng->req->oobbuf.in);
+
+ sg_set_buf(&eng->sg[0], req->databuf.in, req->datalen);
+ sg_set_buf(&eng->sg[1], eng->oobwithstat,
+ req->ooblen + (eng->steps * STAT_BYTES));
+
+ nents = dma_map_sg(eng->dev, eng->sg, 2, DMA_BIDIRECTIONAL);
+ if (!nents)
+ return -EINVAL;
+
+ writel(sg_dma_address(&eng->sg[0]), eng->regs + SDMA_MAIN_ADDR);
+ writel(sg_dma_address(&eng->sg[1]), eng->regs + SDMA_SPARE_ADDR);
+
+ mxic_ecc_enable_engine(eng);
+
+ return 0;
+}
+
+static int mxic_ecc_finish_io_req_pipelined(struct nand_device *nand,
+ struct nand_page_io_req *req)
+{
+ struct mxic_ecc_engine *eng = nand->ecc.ctx.priv;
+ struct mtd_info *mtd = nanddev_to_mtd(nand);
+ int ret = 0;
+
+ if (req->mode == MTD_OPS_RAW)
+ return 0;
+
+ mxic_ecc_disable_engine(eng);
+
+ dma_unmap_sg(eng->dev, eng->sg, 2, DMA_BIDIRECTIONAL);
+
+ if (req->type == NAND_PAGE_READ) {
+ mxic_ecc_extract_status_bytes(eng, eng->oobwithstat);
+ mxic_ecc_reconstruct_oobbuf(eng, eng->req->oobbuf.in,
+ eng->oobwithstat);
+ ret = mxic_ecc_count_biterrs(eng, mtd);
+ }
+
+ nand_ecc_restore_req(&eng->req_ctx, req);
+
+ return ret;
+}
+
static struct nand_ecc_engine_ops mxic_ecc_engine_external_ops = {
.init_ctx = mxic_ecc_init_ctx_external,
.cleanup_ctx = mxic_ecc_cleanup_ctx,
@@ -607,6 +732,23 @@ static struct nand_ecc_engine_ops mxic_ecc_engine_external_ops = {
.finish_io_req = mxic_ecc_finish_io_req_external,
};

+static struct nand_ecc_engine_ops mxic_ecc_engine_pipelined_ops = {
+ .init_ctx = mxic_ecc_init_ctx_pipelined,
+ .cleanup_ctx = mxic_ecc_cleanup_ctx,
+ .prepare_io_req = mxic_ecc_prepare_io_req_pipelined,
+ .finish_io_req = mxic_ecc_finish_io_req_pipelined,
+};
+
+struct nand_ecc_engine_ops *mxic_ecc_get_pipelined_ops(void)
+{
+ return &mxic_ecc_engine_pipelined_ops;
+}
+EXPORT_SYMBOL_GPL(mxic_ecc_get_pipelined_ops);
+
+/*
+ * Only the external ECC engine is exported as the pipelined is SoC specific, so
+ * it is registered directly by the drivers that wrap it.
+ */
static int mxic_ecc_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
diff --git a/include/linux/mtd/nand-ecc-mxic.h b/include/linux/mtd/nand-ecc-mxic.h
new file mode 100644
index 000000000000..d48b7fe05644
--- /dev/null
+++ b/include/linux/mtd/nand-ecc-mxic.h
@@ -0,0 +1,36 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright © 2019 Macronix
+ * Author: Miquèl Raynal <miquel.raynal@bootlin.com>
+ *
+ * Header for the Macronix external ECC engine.
+ */
+
+#ifndef __MTD_NAND_ECC_MXIC_H__
+#define __MTD_NAND_ECC_MXIC_H__
+
+#include <linux/device.h>
+
+struct mxic_ecc_engine;
+
+#if IS_ENABLED(CONFIG_MTD_NAND_ECC_MXIC)
+
+struct nand_ecc_engine_ops *mxic_ecc_get_pipelined_ops(void);
+int mxic_ecc_process_data(struct mxic_ecc_engine *eng, dma_addr_t dirmap);
+
+#else /* !CONFIG_MTD_NAND_ECC_MXIC */
+
+struct nand_ecc_engine_ops *mxic_ecc_get_pipelined_ops(void)
+{
+ return NULL;
+}
+
+static inline
+int mxic_ecc_process_data(struct mxic_ecc_engine *eng, dma_addr_t dirmap)
+{
+ return -ENOTSUPP;
+}
+
+#endif /* CONFIG_MTD_NAND_ECC_MXIC */
+
+#endif /* __MTD_NAND_ECC_MXIC_H__ */
--
2.27.0
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