[RFC PATCH nand/next 1/4] mtd: nand: Create param.c to do CRC check and bitwise majority for Parameter & CASN page

[Sky Huang <SkyLake.Huang@mediatek.com>]

From: "Sky.Huang" <skylake.huang@mediatek.com>

Create drivers/mtd/nand/param.c so ONFI parameter page & CASN page
can both use nanddev_crc16() and nanddev_bit_wise_majority() directly
like this:
* For ONFI Parameter page:
onfi_crc16() -> nanddev_crc16()
* For CASN page: nanddev_crc16()

nanddev_bit_wise_majority() is same as nand_bit_wise_majority().
nanddev_crc16() is same as onfi_crc16(). But there are lots of
onfi_crc16() call, so keep onfi_crc16() there and hook it to
nanddev_crc16().

Signed-off-by: Sky Huang <skylake.huang@mediatek.com>
---
 drivers/mtd/nand/Makefile        |  2 +-
 drivers/mtd/nand/param.c         | 52 ++++++++++++++++++++++++++++++++
 drivers/mtd/nand/raw/nand_onfi.c | 43 ++------------------------
 include/linux/mtd/param.h        | 20 ++++++++++++
 4 files changed, 76 insertions(+), 41 deletions(-)
 create mode 100644 drivers/mtd/nand/param.c
 create mode 100644 include/linux/mtd/param.h

diff --git a/drivers/mtd/nand/Makefile b/drivers/mtd/nand/Makefile
index 19e1291ac4d5..790bde0148d1 100644
--- a/drivers/mtd/nand/Makefile
+++ b/drivers/mtd/nand/Makefile
@@ -1,6 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0
 
-nandcore-objs := core.o bbt.o
+nandcore-objs := core.o bbt.o param.o
 obj-$(CONFIG_MTD_NAND_CORE) += nandcore.o
 obj-$(CONFIG_MTD_NAND_ECC_MEDIATEK) += ecc-mtk.o
 
diff --git a/drivers/mtd/nand/param.c b/drivers/mtd/nand/param.c
new file mode 100644
index 000000000000..f67b9fe633d9
--- /dev/null
+++ b/drivers/mtd/nand/param.c
@@ -0,0 +1,52 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2023 - Mediatek
+ *
+ * Author: Sky Huang <SkyLake.Huang@mediatek.com>
+ */
+
+#include <linux/mtd/param.h>
+
+u16 nanddev_crc16(u16 crc, u8 const *p, size_t len)
+{
+	int i;
+
+	while (len--) {
+		crc ^= *p++ << 8;
+		for (i = 0; i < 8; i++)
+			crc = (crc << 1) ^ ((crc & 0x8000) ? 0x8005 : 0);
+	}
+
+	return crc;
+}
+
+/*
+ * Recover data with bit-wise majority
+ */
+void nanddev_bit_wise_majority(const void **srcbufs,
+				   unsigned int nsrcbufs,
+				   void *dstbuf,
+				   unsigned int bufsize)
+{
+	int i, j, k;
+
+	for (i = 0; i < bufsize; i++) {
+		u8 val = 0;
+
+		for (j = 0; j < 8; j++) {
+			unsigned int cnt = 0;
+
+			for (k = 0; k < nsrcbufs; k++) {
+				const u8 *srcbuf = srcbufs[k];
+
+				if (srcbuf[i] & BIT(j))
+					cnt++;
+			}
+
+			if (cnt > nsrcbufs / 2)
+				val |= BIT(j);
+		}
+
+		((u8 *)dstbuf)[i] = val;
+	}
+}
diff --git a/drivers/mtd/nand/raw/nand_onfi.c b/drivers/mtd/nand/raw/nand_onfi.c
index 861975e44b55..5d330dd53e8f 100644
--- a/drivers/mtd/nand/raw/nand_onfi.c
+++ b/drivers/mtd/nand/raw/nand_onfi.c
@@ -12,6 +12,7 @@
  * This file contains all ONFI helpers.
  */
 
+#include <linux/mtd/param.h>
 #include <linux/slab.h>
 
 #include "internals.h"
@@ -20,14 +21,7 @@
 
 u16 onfi_crc16(u16 crc, u8 const *p, size_t len)
 {
-	int i;
-	while (len--) {
-		crc ^= *p++ << 8;
-		for (i = 0; i < 8; i++)
-			crc = (crc << 1) ^ ((crc & 0x8000) ? 0x8005 : 0);
-	}
-
-	return crc;
+	return nanddev_crc16(crc, p, len);
 }
 
 /* Parse the Extended Parameter Page. */
@@ -107,37 +101,6 @@ static int nand_flash_detect_ext_param_page(struct nand_chip *chip,
 	return ret;
 }
 
-/*
- * Recover data with bit-wise majority
- */
-static void nand_bit_wise_majority(const void **srcbufs,
-				   unsigned int nsrcbufs,
-				   void *dstbuf,
-				   unsigned int bufsize)
-{
-	int i, j, k;
-
-	for (i = 0; i < bufsize; i++) {
-		u8 val = 0;
-
-		for (j = 0; j < 8; j++) {
-			unsigned int cnt = 0;
-
-			for (k = 0; k < nsrcbufs; k++) {
-				const u8 *srcbuf = srcbufs[k];
-
-				if (srcbuf[i] & BIT(j))
-					cnt++;
-			}
-
-			if (cnt > nsrcbufs / 2)
-				val |= BIT(j);
-		}
-
-		((u8 *)dstbuf)[i] = val;
-	}
-}
-
 /*
  * Check if the NAND chip is ONFI compliant, returns 1 if it is, 0 otherwise.
  */
@@ -200,7 +163,7 @@ int nand_onfi_detect(struct nand_chip *chip)
 			srcbufs[j] = pbuf + j;
 
 		pr_warn("Could not find a valid ONFI parameter page, trying bit-wise majority to recover it\n");
-		nand_bit_wise_majority(srcbufs, ONFI_PARAM_PAGES, pbuf,
+		nanddev_bit_wise_majority(srcbufs, ONFI_PARAM_PAGES, pbuf,
 				       sizeof(*pbuf));
 
 		crc = onfi_crc16(ONFI_CRC_BASE, (u8 *)pbuf, 254);
diff --git a/include/linux/mtd/param.h b/include/linux/mtd/param.h
new file mode 100644
index 000000000000..39636f66f1b4
--- /dev/null
+++ b/include/linux/mtd/param.h
@@ -0,0 +1,20 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) 2023 - Mediatek
+ *
+ * Author: Sky Huang <SkyLake.Huang@mediatek.com>
+ */
+
+#ifndef __LINUX_NAND_PARAM
+#define __LINUX_NAND_PARAM
+
+#include <linux/io.h>
+
+u16 nanddev_crc16(u16 crc, u8 const *p, size_t len);
+void nanddev_bit_wise_majority(const void **srcbufs,
+				   unsigned int nsrcbufs,
+				   void *dstbuf,
+				   unsigned int bufsize);
+
+#endif /* __LINUX_NAND_PARAM */
+
-- 
2.45.2