[RFC 23/47] mtd: nand: stm_nand_bch: read and write page (BCH)

Lee Jones
2014-03-25T08:21:30Z

Use DMA to read and/or write a single page of data.

Signed-off-by: Lee Jones <lee.jones@linaro.org>
---
drivers/mtd/nand/stm_nand_bch.c | 119 ++++++++++++++++++++++++++++++++++++++++
1 file changed, 119 insertions(+)

diff --git a/drivers/mtd/nand/stm_nand_bch.c b/drivers/mtd/nand/stm_nand_bch.c
index 7874d85..6323590 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>
@@ -345,6 +346,124 @@ 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((unsigned long)buf & (NANDI_BCH_DMA_ALIGNMENT - 1));
+ 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 'sectors_per_page' bits at zero.
+ */
+ ret = check_erased_page(buf, page_size,
+ nandi->sectors_per_page);
+ 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;
+}
+
+/* Returns the status of the NAND device following the write operation */
+static uint8_t bch_write_page(struct nandi_controller *nandi,
+ loff_t offs, const uint8_t *buf)
+{
+ struct bch_prog *prog = &bch_prog_write_page;
+ uint32_t page_size = nandi->info.mtd.writesize;
+ uint8_t *p = (uint8_t *)buf;
+ unsigned long list_phys;
+ unsigned long buf_phys;
+ uint8_t status;
+
+ dev_dbg(nandi->dev, "%s: offs = 0x%012llx\n", __func__, offs);
+
+ BUG_ON((unsigned int)buf & (NANDI_BCH_DMA_ALIGNMENT - 1));
+ BUG_ON(offs & (page_size - 1));
+
+ emiss_nandi_select(STM_NANDI_BCH);
+
+ nandi_enable_interrupts(nandi, NANDBCH_INT_SEQNODESOVER);
+ reinit_completion(&nandi->seq_completed);
+
+ prog->addr = (uint32_t)((offs >> (nandi->page_shift - 8)) & 0xffffff00);
+
+ buf_phys = dma_map_single(NULL, p, page_size, DMA_TO_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);
+
+ status = (uint8_t)(readl(nandi->base +
+ NANDBCH_CHECK_STATUS_REG_A) & 0xff);
+
+ return status;
+}
+
/*
* Initialisation
*/
--
1.8.3.2