mtd: nand: denali: allow to override revision number

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Gitweb:     http://git.infradead.org/?p=mtd-2.6.git;a=commit;h=e7beeeec854c40c28caa53bd84fdf26e9e459f06
Commit:     e7beeeec854c40c28caa53bd84fdf26e9e459f06
Parent:     3f5c35819fc37d5f35680a55327c940b6e8fad41
Author:     Masahiro Yamada <yamada.masahiro at socionext.com>
AuthorDate: Thu Mar 30 15:45:57 2017 +0900
Committer:  Boris Brezillon <boris.brezillon at free-electrons.com>
CommitDate: Tue Apr 25 14:18:37 2017 +0200

    mtd: nand: denali: allow to override revision number
    
    Commit 271707b1d817 ("mtd: nand: denali: max_banks calculation
    changed in revision 5.1") added a revision check to support the
    new max_banks encoding.  Its git-log states "The encoding of
    max_banks changed in Denali revision 5.1".
    
    There are exceptional cases, for example, the revision register on
    some UniPhier SoCs says the IP is 5.0 but the max_banks is encoded
    in the new format.
    
    This IP updates the resister specification from time to time (often
    breaking the backward compatibility), but the revision number is not
    incremented correctly.
    
    The max_banks is not only the case that needs revision checking.
    Let's allow to override an incorrect revision number.
    
    Signed-off-by: Masahiro Yamada <yamada.masahiro at socionext.com>
    Signed-off-by: Boris Brezillon <boris.brezillon at free-electrons.com>
---
 drivers/mtd/nand/denali.c    | 23 +++++++++++++----------
 drivers/mtd/nand/denali.h    |  3 +--
 drivers/mtd/nand/denali_dt.c |  5 ++++-
 3 files changed, 18 insertions(+), 13 deletions(-)

diff --git a/drivers/mtd/nand/denali.c b/drivers/mtd/nand/denali.c
index 417a895..16634df 100644
--- a/drivers/mtd/nand/denali.c
+++ b/drivers/mtd/nand/denali.c
@@ -419,17 +419,12 @@ static void find_valid_banks(struct denali_nand_info *denali)
 static void detect_max_banks(struct denali_nand_info *denali)
 {
 	uint32_t features = ioread32(denali->flash_reg + FEATURES);
-	/*
-	 * Read the revision register, so we can calculate the max_banks
-	 * properly: the encoding changed from rev 5.0 to 5.1
-	 */
-	u32 revision = MAKE_COMPARABLE_REVISION(
-				ioread32(denali->flash_reg + REVISION));
 
-	if (revision < REVISION_5_1)
-		denali->max_banks = 2 << (features & FEATURES__N_BANKS);
-	else
-		denali->max_banks = 1 << (features & FEATURES__N_BANKS);
+	denali->max_banks = 1 << (features & FEATURES__N_BANKS);
+
+	/* the encoding changed from rev 5.0 to 5.1 */
+	if (denali->revision < 0x0501)
+		denali->max_banks <<= 1;
 }
 
 static uint16_t denali_nand_timing_set(struct denali_nand_info *denali)
@@ -1320,6 +1315,14 @@ static void denali_cmdfunc(struct mtd_info *mtd, unsigned int cmd, int col,
 static void denali_hw_init(struct denali_nand_info *denali)
 {
 	/*
+	 * The REVISION register may not be reliable.  Platforms are allowed to
+	 * override it.
+	 */
+	if (!denali->revision)
+		denali->revision =
+				swab16(ioread32(denali->flash_reg + REVISION));
+
+	/*
 	 * tell driver how many bit controller will skip before
 	 * writing ECC code in OOB, this register may be already
 	 * set by firmware. So we read this value out.
diff --git a/drivers/mtd/nand/denali.h b/drivers/mtd/nand/denali.h
index 1f413d0..ec00485 100644
--- a/drivers/mtd/nand/denali.h
+++ b/drivers/mtd/nand/denali.h
@@ -179,8 +179,6 @@
 
 #define REVISION				0x370
 #define     REVISION__VALUE				0xffff
-#define MAKE_COMPARABLE_REVISION(x)		swab16((x) & REVISION__VALUE)
-#define REVISION_5_1				0x00000501
 
 #define ONFI_DEVICE_FEATURES			0x380
 #define     ONFI_DEVICE_FEATURES__VALUE			0x003f
@@ -343,6 +341,7 @@ struct denali_nand_info {
 	int devnum;	/* represent how many nands connected */
 	int bbtskipbytes;
 	int max_banks;
+	unsigned int revision;
 	unsigned int caps;
 };
 
diff --git a/drivers/mtd/nand/denali_dt.c b/drivers/mtd/nand/denali_dt.c
index ada3863..df9ef36 100644
--- a/drivers/mtd/nand/denali_dt.c
+++ b/drivers/mtd/nand/denali_dt.c
@@ -30,6 +30,7 @@ struct denali_dt {
 };
 
 struct denali_dt_data {
+	unsigned int revision;
 	unsigned int caps;
 };
 
@@ -60,8 +61,10 @@ static int denali_dt_probe(struct platform_device *pdev)
 	denali = &dt->denali;
 
 	data = of_device_get_match_data(&pdev->dev);
-	if (data)
+	if (data) {
+		denali->revision = data->revision;
 		denali->caps = data->caps;
+	}
 
 	denali->platform = DT;
 	denali->dev = &pdev->dev;