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Date: Thu, 1 May 2014 10:56:32 +0100
From: Lee Jones <lee.jones@...aro.org>
To: linux-kernel@...r.kernel.org
Cc: computersforpeace@...il.com, linux-mtd@...ts.infradead.org,
kernel@...inux.com, Lee Jones <lee.jones@...aro.org>
Subject: [PATCH 25/47] mtd: nand: stm_nand_bch: provide read functionality (BCH)
Use DMA to read a single page of data.
Signed-off-by: Lee Jones <lee.jones@...aro.org>
---
drivers/mtd/nand/stm_nand_bch.c | 96 +++++++++++++++++++++++++++++++++++++++++
1 file changed, 96 insertions(+)
diff --git a/drivers/mtd/nand/stm_nand_bch.c b/drivers/mtd/nand/stm_nand_bch.c
index 2ff72c9..72c9734 100644
--- a/drivers/mtd/nand/stm_nand_bch.c
+++ b/drivers/mtd/nand/stm_nand_bch.c
@@ -21,6 +21,7 @@
#include <linux/interrupt.h>
#include <linux/device.h>
#include <linux/platform_device.h>
+#include <linux/dma-mapping.h>
#include <linux/completion.h>
#include <linux/mtd/nand.h>
#include <linux/mtd/stm_nand.h>
@@ -512,6 +513,99 @@ static int check_erased_page(uint8_t *data, uint32_t page_size, int max_zeros)
return zeros;
}
+/* Returns the number of ECC errors, or '-1' for uncorrectable error */
+static int bch_read_page(struct nandi_controller *nandi,
+ loff_t offs,
+ uint8_t *buf)
+{
+ struct bch_prog *prog = &bch_prog_read_page;
+ uint32_t page_size = nandi->info.mtd.writesize;
+ unsigned long list_phys;
+ unsigned long buf_phys;
+ uint32_t ecc_err;
+ int ret = 0;
+
+ dev_dbg(nandi->dev, "%s: offs = 0x%012llx\n", __func__, offs);
+
+ BUG_ON(offs & (NANDI_BCH_DMA_ALIGNMENT - 1));
+
+ emiss_nandi_select(STM_NANDI_BCH);
+
+ nandi_enable_interrupts(nandi, NANDBCH_INT_SEQNODESOVER);
+ reinit_completion(&nandi->seq_completed);
+
+ /* Reset ECC stats */
+ writel(CFG_RESET_ECC_ALL | CFG_ENABLE_AFM,
+ nandi->base + NANDBCH_CONTROLLER_CFG);
+ writel(CFG_ENABLE_AFM, nandi->base + NANDBCH_CONTROLLER_CFG);
+
+ prog->addr = (uint32_t)((offs >> (nandi->page_shift - 8)) & 0xffffff00);
+
+ buf_phys = dma_map_single(NULL, buf, page_size, DMA_FROM_DEVICE);
+
+ memset(nandi->buf_list, 0x00, NANDI_BCH_BUF_LIST_SIZE);
+ nandi->buf_list[0] = buf_phys | (nandi->sectors_per_page - 1);
+
+ list_phys = dma_map_single(NULL, nandi->buf_list,
+ NANDI_BCH_BUF_LIST_SIZE, DMA_TO_DEVICE);
+
+ writel(list_phys, nandi->base + NANDBCH_BUFFER_LIST_PTR);
+
+ bch_load_prog_cpu(nandi, prog);
+
+ bch_wait_seq(nandi);
+
+ nandi_disable_interrupts(nandi, NANDBCH_INT_SEQNODESOVER);
+
+ dma_unmap_single(NULL, list_phys, NANDI_BCH_BUF_LIST_SIZE,
+ DMA_TO_DEVICE);
+ dma_unmap_single(NULL, buf_phys, page_size, DMA_FROM_DEVICE);
+
+ /* Use the maximum per-sector ECC count! */
+ ecc_err = readl(nandi->base + NANDBCH_ECC_SCORE_REG_A) & 0xff;
+ if (ecc_err == 0xff) {
+ /*
+ * Downgrade uncorrectable ECC error for an erased page,
+ * tolerating 'bitflip_threshold' bits at zero.
+ */
+ ret = check_erased_page(buf, page_size,
+ nandi->bitflip_threshold);
+ if (ret >= 0)
+ dev_dbg(nandi->dev,
+ "%s: erased page detected: \n"
+ " downgrading uncorrectable ECC error.\n",
+ __func__);
+ } else {
+ ret = (int)ecc_err;
+ }
+
+ return ret;
+}
+
+static int bch_read(struct mtd_info *mtd, struct nand_chip *chip,
+ uint8_t *buf, int oob_required, int page)
+{
+ struct nandi_controller *nandi = chip->priv;
+ uint32_t page_size = mtd->writesize;
+ loff_t offs = page * page_size;
+ bool bounce = false;
+ uint8_t *p;
+ int ret;
+
+ if (((unsigned int)buf & (NANDI_BCH_DMA_ALIGNMENT - 1)) ||
+ (!virt_addr_valid(buf))) /* vmalloc'd buffer! */
+ bounce = true;
+
+ p = bounce ? nandi->page_buf : buf;
+
+ ret = bch_read_page(nandi, offs, p);
+
+ if (bounce)
+ memcpy(buf, p, page_size);
+
+ return ret;
+}
+
/*
* Initialisation
*/
@@ -590,6 +684,8 @@ static void nandi_set_mtd_defaults(struct nandi_controller *nandi,
mtd->flags = MTD_CAP_NANDFLASH;
mtd->ecclayout = &info->ecclayout;
mtd->subpage_sft = 0;
+
+ chip->ecc.read_page = bch_read;
}
/*
--
1.8.3.2
--
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