[MTD] [NAND] Use rslib for CAFÉ ECC

Signed-off-by: Segher Boessenkool <segher@kernel.crashing.org>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>

1 files changed, 98 insertions, 12 deletions

diff --git a/drivers/mtd/nand/cafe.c b/drivers/mtd/nand/cafe.c
index c328a7514510..05f6ec9f5aa7 100644
--- a/drivers/mtd/nand/cafe.c
+++ b/drivers/mtd/nand/cafe.c
@@ -11,6 +11,7 @@
 #undef DEBUG
 #include <linux/mtd/mtd.h>
 #include <linux/mtd/nand.h>
+#include <linux/rslib.h>
 #include <linux/pci.h>
 #include <linux/delay.h>
 #include <linux/interrupt.h>
@@ -46,13 +47,11 @@
 #define CAFE_GLOBAL_IRQ_MASK    0x300c
 #define CAFE_NAND_RESET         0x3034
 
-int cafe_correct_ecc(unsigned char *buf,
-                     unsigned short *chk_syndrome_list);
-
 struct cafe_priv {
         struct nand_chip nand;
         struct pci_dev *pdev;
         void __iomem *mmio;
+        struct rs_control *rs;
         uint32_t ctl1;
         uint32_t ctl2;
         int datalen;
@@ -374,28 +373,66 @@ static int cafe_nand_read_page(struct mtd_info *mtd, struct nand_chip *chip,
         chip->read_buf(mtd, chip->oob_poi, mtd->oobsize);
 
         if (checkecc && cafe_readl(cafe, NAND_ECC_RESULT) & (1<<18)) {
-                unsigned short syn[8];
-                int i;
+                unsigned short syn[8], pat[4];
+                int pos[4];
+                u8 *oob = chip->oob_poi;
+                int i, n;
 
                 for (i=0; i<8; i+=2) {
                         uint32_t tmp = cafe_readl(cafe, NAND_ECC_SYN01 + (i*2));
-                        syn[i] = tmp & 0xfff;
-                        syn[i+1] = (tmp >> 16) & 0xfff;
+                        syn[i] = cafe->rs->index_of[tmp & 0xfff];
+                        syn[i+1] = cafe->rs->index_of[(tmp >> 16) & 0xfff];
+                }
+
+                n = decode_rs16(cafe->rs, NULL, NULL, 1367, syn, 0, pos, 0,
+                                pat);
+
+                for (i = 0; i < n; i++) {
+                        int p = pos[i];
+
+                        /* The 12-bit symbols are mapped to bytes here */
+
+                        if (p > 1374) {
+                                /* out of range */
+                                n = -1374;
+                        } else if (p == 0) {
+                                /* high four bits do not correspond to data */
+                                if (pat[i] > 0xff)
+                                        n = -2048;
+                                else
+                                        buf[0] ^= pat[i];
+                        } else if (p == 1365) {
+                                buf[2047] ^= pat[i] >> 4;
+                                oob[0] ^= pat[i] << 4;
+                        } else if (p > 1365) {
+                                if ((p & 1) == 1) {
+                                        oob[3*p/2 - 2048] ^= pat[i] >> 4;
+                                        oob[3*p/2 - 2047] ^= pat[i] << 4;
+                                } else {
+                                        oob[3*p/2 - 2049] ^= pat[i] >> 8;
+                                        oob[3*p/2 - 2048] ^= pat[i];
+                                }
+                        } else if ((p & 1) == 1) {
+                                buf[3*p/2] ^= pat[i] >> 4;
+                                buf[3*p/2 + 1] ^= pat[i] << 4;
+                        } else {
+                                buf[3*p/2 - 1] ^= pat[i] >> 8;
+                                buf[3*p/2] ^= pat[i];
+                        }
                 }
 
-                if ((i = cafe_correct_ecc(buf, syn)) < 0) {
+                if (n < 0) {
                         dev_dbg(&cafe->pdev->dev, "Failed to correct ECC at %08x\n",
                                 cafe_readl(cafe, NAND_ADDR2) * 2048);
-                        for (i=0; i< 0x5c; i+=4)
+                        for (i = 0; i < 0x5c; i += 4)
                                 printk("Register %x: %08x\n", i, readl(cafe->mmio + i));
                         mtd->ecc_stats.failed++;
                 } else {
-                        dev_dbg(&cafe->pdev->dev, "Corrected %d symbol errors\n", i);
-                        mtd->ecc_stats.corrected += i;
+                        dev_dbg(&cafe->pdev->dev, "Corrected %d symbol errors\n", n);
+                        mtd->ecc_stats.corrected += n;
                 }
         }
 
-
         return 0;
 }
 
@@ -525,6 +562,48 @@ static int cafe_nand_block_bad(struct mtd_info *mtd, loff_t ofs, int getchip)
         return 0;
 }
 
+/* F_2[X]/(X**6+X+1)  */
+static unsigned short __devinit gf64_mul(u8 a, u8 b)
+{
+        u8 c;
+        unsigned int i;
+
+        c = 0;
+        for (i = 0; i < 6; i++) {
+                if (a & 1)
+                        c ^= b;
+                a >>= 1;
+                b <<= 1;
+                if ((b & 0x40) != 0)
+                        b ^= 0x43;
+        }
+
+        return c;
+}
+
+/* F_64[X]/(X**2+X+A**-1) with A the generator of F_64[X]  */
+static u16 __devinit gf4096_mul(u16 a, u16 b)
+{
+        u8 ah, al, bh, bl, ch, cl;
+
+        ah = a >> 6;
+        al = a & 0x3f;
+        bh = b >> 6;
+        bl = b & 0x3f;
+
+        ch = gf64_mul(ah ^ al, bh ^ bl) ^ gf64_mul(al, bl);
+        cl = gf64_mul(gf64_mul(ah, bh), 0x21) ^ gf64_mul(al, bl);
+
+        return (ch << 6) ^ cl;
+}
+
+static int __devinit cafe_mul(int x)
+{
+        if (x == 0)
+                return 1;
+        return gf4096_mul(x, 0xe01);
+}
+
 static int __devinit cafe_nand_probe(struct pci_dev *pdev,
                                      const struct pci_device_id *ent)
 {
@@ -564,6 +643,12 @@ static int __devinit cafe_nand_probe(struct pci_dev *pdev,
         }
         cafe->nand.buffers = (void *)cafe->dmabuf + 2112;
 
+        cafe->rs = init_rs_non_canonical(12, &cafe_mul, 0, 1, 8);
+        if (!cafe->rs) {
+                err = -ENOMEM;
+                goto out_ior;
+        }
+
         cafe->nand.cmdfunc = cafe_nand_cmdfunc;
         cafe->nand.dev_ready = cafe_device_ready;
         cafe->nand.read_byte = cafe_read_byte;
@@ -713,6 +798,7 @@ static void __devexit cafe_nand_remove(struct pci_dev *pdev)
         cafe_writel(cafe, ~1 & cafe_readl(cafe, GLOBAL_IRQ_MASK), GLOBAL_IRQ_MASK);
         free_irq(pdev->irq, mtd);
         nand_release(mtd);
+        free_rs(cafe->rs);
         pci_iounmap(pdev, cafe->mmio);
         dma_free_coherent(&cafe->pdev->dev, 2112, cafe->dmabuf, cafe->dmaaddr);
         kfree(mtd);