[PATCH v5 06/16] mtd: nand: qcom: erased codeword detection configuration

[Abhishek Sahu]

The NAND controller returns ECC failure during read of completely
erased codeword. The NAND controller has hardware functionality
to detect erased codeword in case of BCH ECC algorithm. The
NAND_ERASED_CW_DETECT_CFG register controls the erased
codeword/page detection controller. This register should be reset
before every page read by setting and clearing bit 0 of
NAND_ERASED_CW_DETECT_CFG.

Reviewed-by: Archit Taneja <arch...@codeaurora.org>
Signed-off-by: Abhishek Sahu <abs...@codeaurora.org>
---

* Changes from v4: None

 drivers/mtd/nand/qcom_nandc.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/drivers/mtd/nand/qcom_nandc.c b/drivers/mtd/nand/qcom_nandc.c
index 9d55e8e..81cfce7 100644
--- a/drivers/mtd/nand/qcom_nandc.c
+++ b/drivers/mtd/nand/qcom_nandc.c
@@ -203,6 +203,11 @@
 #define NAND_BAM_NWD                   BIT(1)
 /* Finish writing in the current BAM sgl and start writing in another BAM sgl 
*/
 #define NAND_BAM_NEXT_SGL              BIT(2)
+/*
+ * Erased codeword status is being used two times in single transfer so this
+ * flag will determine the current value of erased codeword status register
+ */
+#define NAND_ERASED_CW_SET             BIT(4)
 
 /*
  * This data type corresponds to the BAM transaction which will be used for all
@@ -281,6 +286,8 @@ struct nandc_regs {
        __le32 read_location2;
        __le32 read_location3;
 
+       __le32 erased_cw_detect_cfg_clr;
+       __le32 erased_cw_detect_cfg_set;
 };
 
 /*
@@ -810,6 +817,13 @@ static int write_reg_dma(struct qcom_nand_controller 
*nandc, int first,
        if (first == NAND_FLASH_CMD)
                flow_control = true;
 
+       if (first == NAND_ERASED_CW_DETECT_CFG) {
+               if (flags & NAND_ERASED_CW_SET)
+                       vaddr = &regs->erased_cw_detect_cfg_set;
+               else
+                       vaddr = &regs->erased_cw_detect_cfg_clr;
+       }
+
        if (first == NAND_EXEC_CMD)
                flags |= NAND_BAM_NWD;
 
@@ -864,6 +878,9 @@ static void config_nand_page_read(struct 
qcom_nand_controller *nandc)
        write_reg_dma(nandc, NAND_ADDR0, 2, 0);
        write_reg_dma(nandc, NAND_DEV0_CFG0, 3, 0);
        write_reg_dma(nandc, NAND_EBI2_ECC_BUF_CFG, 1, 0);
+       write_reg_dma(nandc, NAND_ERASED_CW_DETECT_CFG, 1, 0);
+       write_reg_dma(nandc, NAND_ERASED_CW_DETECT_CFG, 1,
+                     NAND_ERASED_CW_SET | NAND_BAM_NEXT_SGL);
 }
 
 /*
@@ -2264,6 +2281,10 @@ static int qcom_nand_host_setup(struct qcom_nand_host 
*host)
 
        host->clrflashstatus = FS_READY_BSY_N;
        host->clrreadstatus = 0xc0;
+       nandc->regs->erased_cw_detect_cfg_clr =
+               cpu_to_le32(CLR_ERASED_PAGE_DET);
+       nandc->regs->erased_cw_detect_cfg_set =
+               cpu_to_le32(SET_ERASED_PAGE_DET);
 
        dev_dbg(nandc->dev,
                "cfg0 %x cfg1 %x ecc_buf_cfg %x ecc_bch cfg %x cw_size %d 
cw_data %d strength %d parity_bytes %d steps %d\n",
-- 
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