x1000: add support for simple on-die ECC with NAND flash

Many SPI NAND flash chips have on-die ECC engines that report
ECC status via the status feature register. This code handles
the common case where ECC status is reported with 2 bits: one
bit to indicate if flips were detected & corrected, and another
bit to indicate an uncorrectable error.

Change-Id: I5d587cd960ca9d090d2629e890724a6bc411e70c

2 files changed, 23 insertions, 0 deletions

diff --git a/firmware/target/mips/ingenic_x1000/nand-x1000.c b/firmware/target/mips/ingenic_x1000/nand-x1000.c
index 2b62e8fb42..286dc3c64b 100644
--- a/firmware/target/mips/ingenic_x1000/nand-x1000.c
+++ b/firmware/target/mips/ingenic_x1000/nand-x1000.c
@@ -22,6 +22,7 @@
 #include "nand-x1000.h"
 #include "sfc-x1000.h"
 #include "system.h"
+#include "logf.h"
 #include <string.h>
 
 const struct nand_chip supported_nand_chips[] = {
@@ -151,6 +152,11 @@ static void setup_chip_registers(struct nand_drv* drv)
                      en ? FREG_CFG_QUAD_ENABLE : 0);
     }
 
+    if(drv->chip->flags & NAND_CHIPFLAG_ON_DIE_ECC) {
+        /* Enable on-die ECC */
+        nand_upd_reg(drv, FREG_CFG, FREG_CFG_ECC_ENABLE, FREG_CFG_ECC_ENABLE);
+    }
+
     /* Clear OTP bit to access the main data array */
     nand_upd_reg(drv, FREG_CFG, FREG_CFG_OTP_ENABLE, 0);
 
@@ -249,6 +255,20 @@ int nand_page_read(struct nand_drv* drv, nand_page_t page, void* buffer)
     sfc_exec(drv->cmd_page_read, page, NULL, 0);
     nand_wait_busy(drv);
     sfc_exec(drv->cmd_read_cache, 0, buffer, drv->fpage_size|SFC_READ);
+
+    if(drv->chip->flags & NAND_CHIPFLAG_ON_DIE_ECC) {
+        uint8_t status = nand_get_reg(drv, FREG_STATUS);
+
+        if(status & FREG_STATUS_ECC_UNCOR_ERR) {
+            logf("ecc uncorrectable error on page %08lx", (unsigned long)page);
+            return NAND_ERR_ECC_FAIL;
+        }
+
+        if(status & FREG_STATUS_ECC_HAS_FLIPS) {
+            logf("ecc corrected bitflips on page %08lx", (unsigned long)page);
+        }
+    }
+
     return NAND_SUCCESS;
 }
 
diff --git a/firmware/target/mips/ingenic_x1000/nand-x1000.h b/firmware/target/mips/ingenic_x1000/nand-x1000.h
index 0a22a4ff3c..61e0bbebc9 100644
--- a/firmware/target/mips/ingenic_x1000/nand-x1000.h
+++ b/firmware/target/mips/ingenic_x1000/nand-x1000.h
@@ -32,6 +32,7 @@
 #define NAND_ERR_PROGRAM_FAIL   (-2)
 #define NAND_ERR_ERASE_FAIL     (-3)
 #define NAND_ERR_UNALIGNED      (-4)
+#define NAND_ERR_ECC_FAIL       (-5)
 
 /* keep max page size in sync with the NAND chip table in the .c file */
 #define NAND_DRV_SCRATCHSIZE 32
@@ -43,6 +44,8 @@
 #define NAND_CHIPFLAG_HAS_QE_BIT    0x0002
 /* Chip has 2nd device ID byte */
 #define NAND_CHIPFLAG_HAS_DEVID2    0x0004
+/* True if the chip has on-die ECC */
+#define NAND_CHIPFLAG_ON_DIE_ECC    0x0008
 
 /*                                          cmd   mode             a  d  phase format         has data */
 #define NANDCMD_RESET               SFC_CMD(0xff, SFC_TMODE_1_1_1, 0, 0, SFC_PFMT_ADDR_FIRST, 0)