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@socionext.com>
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>

diff --git a/drivers/mtd/nand/denali.c b/drivers/mtd/nand/denali.c
index 417a8950cf49c4e029589b9e00d63aa0f9c7e9e8..16634df2e39a77ae1e34f68a7b4af0c642232b1e 100644 (file)
--- 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)
@@ -1319,6 +1314,14 @@ static void denali_cmdfunc(struct mtd_info *mtd, unsigned int cmd, int col,
 /* Initialization code to bring the device up to a known good state */
 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

diff --git a/drivers/mtd/nand/denali.h b/drivers/mtd/nand/denali.h
index 1f413d05a0107ceadd3606636fc0b7237897ec04..ec004850652a7a67df8be4c984d70db6faf86954 100644 (file)
--- 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 ada38636122c5b10f0bd8e03de7fba9f5413d0ed..df9ef36cc2ce3323da883e722152bf0b5a1d2f8b 100644 (file)
--- 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;