[MTD] NAND: CAFÉ NAND driver cleanup, fix ECC on reading empty flash

Signed-off-by: David Woodhouse <dwmw2@infradead.org>

1 files changed, 104 insertions, 45 deletions

diff --git a/drivers/mtd/nand/cafe.c b/drivers/mtd/nand/cafe.c
index 1fe110836cc1..10132efd0588 100644
--- a/drivers/mtd/nand/cafe.c
+++ b/drivers/mtd/nand/cafe.c
@@ -1,5 +1,5 @@
 /* 
- * cafe_nand.c
+ * Driver for One Laptop Per Child ‘CAFÉ’ controller, aka Marvell 88ALP01
  *
  * Copyright © 2006 Red Hat, Inc.
  * Copyright © 2006 David Woodhouse <dwmw2@infradead.org>
@@ -30,13 +30,13 @@
 #define CAFE_NAND_TIMING3       0x2c
 #define CAFE_NAND_NONMEM        0x30
 #define CAFE_NAND_ECC_RESULT    0x3C
+#define CAFE_NAND_DMA_CTRL      0x40
+#define CAFE_NAND_DMA_ADDR0     0x44
+#define CAFE_NAND_DMA_ADDR1     0x48
 #define CAFE_NAND_ECC_SYN01     0x50
 #define CAFE_NAND_ECC_SYN23     0x54
 #define CAFE_NAND_ECC_SYN45     0x58
 #define CAFE_NAND_ECC_SYN67     0x5c
-#define CAFE_NAND_DMA_CTRL      0x40
-#define CAFE_NAND_DMA_ADDR0     0x44
-#define CAFE_NAND_DMA_ADDR1     0x48
 #define CAFE_NAND_READ_DATA     0x1000
 #define CAFE_NAND_WRITE_DATA    0x2000
 
@@ -75,12 +75,14 @@ static int cafe_device_ready(struct mtd_info *mtd)
 {
         struct cafe_priv *cafe = mtd->priv;
         int result = !!(readl(cafe->mmio + CAFE_NAND_STATUS) | 0x40000000);
-
         uint32_t irqs = readl(cafe->mmio + CAFE_NAND_IRQ);
+
         writel(irqs, cafe->mmio+CAFE_NAND_IRQ);
+
         cafe_dev_dbg(&cafe->pdev->dev, "NAND device is%s ready, IRQ %x (%x) (%x,%x)\n",
                 result?"":" not", irqs, readl(cafe->mmio + CAFE_NAND_IRQ),
                 readl(cafe->mmio + 0x3008), readl(cafe->mmio + 0x300c));
+
         return result;
 }
 
@@ -93,6 +95,7 @@ static void cafe_write_buf(struct mtd_info *mtd, const uint8_t *buf, int len)
                 memcpy(cafe->dmabuf + cafe->datalen, buf, len);
         else
                 memcpy_toio(cafe->mmio + CAFE_NAND_WRITE_DATA + cafe->datalen, buf, len);
+
         cafe->datalen += len;
 
         cafe_dev_dbg(&cafe->pdev->dev, "Copy 0x%x bytes to write buffer. datalen 0x%x\n",
@@ -131,14 +134,13 @@ static void cafe_nand_cmdfunc(struct mtd_info *mtd, unsigned command,
         int adrbytes = 0;
         uint32_t ctl1;
         uint32_t doneint = 0x80000000;
-        int i;
 
         cafe_dev_dbg(&cafe->pdev->dev, "cmdfunc %02x, 0x%x, 0x%x\n",
                 command, column, page_addr);
 
         if (command == NAND_CMD_ERASE2 || command == NAND_CMD_PAGEPROG) {
                 /* Second half of a command we already calculated */
-                writel(cafe->ctl2 | 0x100 | command, cafe->mmio + 0x04);
+                writel(cafe->ctl2 | 0x100 | command, cafe->mmio + CAFE_NAND_CTRL2);
                 ctl1 = cafe->ctl1;
                 cafe_dev_dbg(&cafe->pdev->dev, "Continue command, ctl1 %08x, #data %d\n",
                           cafe->ctl1, cafe->nr_data);
@@ -158,12 +160,12 @@ static void cafe_nand_cmdfunc(struct mtd_info *mtd, unsigned command,
            for small-page chips, to position the buffer correctly? */
 
         if (column != -1) {
-                writel(column, cafe->mmio + 0x1c);
+                writel(column, cafe->mmio + CAFE_NAND_ADDR1);
                 adrbytes = 2;
                 if (page_addr != -1)
                         goto write_adr2;
         } else if (page_addr != -1) {
-                writel(page_addr & 0xffff, cafe->mmio + 0x1c);
+                writel(page_addr & 0xffff, cafe->mmio + CAFE_NAND_ADDR1);
                 page_addr >>= 16;
         write_adr2:
                 writel(page_addr, cafe->mmio+0x20);
@@ -212,13 +214,15 @@ static void cafe_nand_cmdfunc(struct mtd_info *mtd, unsigned command,
                 writel(cafe->ctl2 | 0x100 | NAND_CMD_READSTART, cafe->mmio + CAFE_NAND_CTRL2);
 
  do_command:
-#if 0
-        // ECC on read only works if we ...
+#if 1
+        /* http://dev.laptop.org/ticket/200
+           ECC on read only works if we read precisely 0x80e bytes */
         if (cafe->datalen == 2112)
                 cafe->datalen = 2062;
 #endif
         cafe_dev_dbg(&cafe->pdev->dev, "dlen %x, ctl1 %x, ctl2 %x\n", 
                 cafe->datalen, ctl1, readl(cafe->mmio+CAFE_NAND_CTRL2));
+
         /* NB: The datasheet lies -- we really should be subtracting 1 here */
         writel(cafe->datalen, cafe->mmio + CAFE_NAND_DATA_LEN);
         writel(0x90000000, cafe->mmio + CAFE_NAND_IRQ);
@@ -232,18 +236,16 @@ static void cafe_nand_cmdfunc(struct mtd_info *mtd, unsigned command,
                            the command. */
                         doneint = 0x10000000;
                 }
-                writel(dmactl, cafe->mmio + 0x40);
+                writel(dmactl, cafe->mmio + CAFE_NAND_DMA_CTRL);
         }
-#if 0
-        printk("DMA setup is %x, status %x, ctl1 %x\n", readl(cafe->mmio + 0x40), readl(cafe->mmio + 0x0c), readl(cafe->mmio));
-        printk("DMA setup is %x, status %x, ctl1 %x\n", readl(cafe->mmio + 0x40), readl(cafe->mmio + 0x0c), readl(cafe->mmio));
-#endif
         cafe->datalen = 0;
 
 #if 0
+        { int i;
         printk("About to write command %08x\n", ctl1);
         for (i=0; i< 0x5c; i+=4)
                 printk("Register %x: %08x\n", i, readl(cafe->mmio + i));
+        }
 #endif
         writel(ctl1, cafe->mmio + CAFE_NAND_CTRL1);
         /* Apply this short delay always to ensure that we do wait tWB in
@@ -299,6 +301,7 @@ static void cafe_select_chip(struct mtd_info *mtd, int chipnr)
         //struct cafe_priv *cafe = mtd->priv;
         //      cafe_dev_dbg(&cafe->pdev->dev, "select_chip %d\n", chipnr);
 }
+
 static int cafe_nand_interrupt(int irq, void *id, struct pt_regs *regs)
 {
         struct mtd_info *mtd = id;
@@ -347,14 +350,34 @@ static int cafe_nand_read_oob(struct mtd_info *mtd, struct nand_chip *chip,
  * The hw generator calculates the error syndrome automatically. Therefor
  * we need a special oob layout and handling.
  */
+
+static unsigned short cafe_empty_syndromes[8] = { 4095, 748, 2629, 2920, 875, 1454, 51, 1456 };
+
+static int is_all_ff(unsigned char *buf, int len)
+{
+        unsigned long *lbuf = (void *)buf;
+        int i;
+
+        for (i=0; i < (len/sizeof(long)); i++) {
+                if (lbuf[i] != ~0UL)
+                        return 0;
+        }
+        i *= sizeof(long);
+        for (; i< len; i++) {
+                if (buf[i] != 0xff)
+                        return 0;
+        }
+        return 1;
+}
+
 static int cafe_nand_read_page(struct mtd_info *mtd, struct nand_chip *chip,
                                uint8_t *buf)
 {
         struct cafe_priv *cafe = mtd->priv;
 
-        dev_dbg(&cafe->pdev->dev, "ECC result %08x SYN1,2 %08x\n",
-                readl(cafe->mmio + CAFE_NAND_ECC_RESULT),
-                readl(cafe->mmio + CAFE_NAND_ECC_SYN01));
+        cafe_dev_dbg(&cafe->pdev->dev, "ECC result %08x SYN1,2 %08x\n",
+                     readl(cafe->mmio + CAFE_NAND_ECC_RESULT),
+                     readl(cafe->mmio + CAFE_NAND_ECC_SYN01));
 
         chip->read_buf(mtd, buf, mtd->writesize);
         chip->read_buf(mtd, chip->oob_poi, mtd->oobsize);
@@ -369,7 +392,13 @@ static int cafe_nand_read_page(struct mtd_info *mtd, struct nand_chip *chip,
                         syn[i+1] = (tmp >> 16) & 0xfff;
                 } 
 
-                if ((i = cafe_correct_ecc(buf, syn)) < 0) {
+                /* FIXME: http://dev.laptop.org/ticket/215 */
+                if (!memcmp(syn, cafe_empty_syndromes, sizeof(syn))
+                    && is_all_ff(chip->oob_poi, 14)
+                    && is_all_ff(buf, mtd->writesize)) {
+                        dev_dbg(&cafe->pdev->dev, "ECC error reported on empty block\n");
+                        /* It was an empty block. Nothing to fix here except the hardware */
+                } else if ((i = cafe_correct_ecc(buf, syn)) < 0) {
                         dev_dbg(&cafe->pdev->dev, "Failed to correct ECC\n");
                         mtd->ecc_stats.failed++;
                 } else {
@@ -389,9 +418,13 @@ static struct nand_ecclayout cafe_oobinfo_2048 = {
 };
 
 /* Ick. The BBT code really ought to be able to work this bit out 
-   for itself from the above */
-static uint8_t cafe_bbt_pattern[] = {'B', 'b', 't', '0' };
-static uint8_t cafe_mirror_pattern[] = {'1', 't', 'b', 'B' };
+   for itself from the above, at least for the 2KiB case */
+static uint8_t cafe_bbt_pattern_2048[] = { 'B', 'b', 't', '0' };
+static uint8_t cafe_mirror_pattern_2048[] = { '1', 't', 'b', 'B' };
+
+static uint8_t cafe_bbt_pattern_512[] = { 0xBB };
+static uint8_t cafe_mirror_pattern_512[] = { 0xBC };
+
 
 static struct nand_bbt_descr cafe_bbt_main_descr_2048 = {
         .options = NAND_BBT_LASTBLOCK | NAND_BBT_CREATE | NAND_BBT_WRITE
@@ -400,7 +433,7 @@ static struct nand_bbt_descr cafe_bbt_main_descr_2048 = {
         .len = 4,
         .veroffs = 18,
         .maxblocks = 4,
-        .pattern = cafe_bbt_pattern
+        .pattern = cafe_bbt_pattern_2048
 };
 
 static struct nand_bbt_descr cafe_bbt_mirror_descr_2048 = {
@@ -410,7 +443,7 @@ static struct nand_bbt_descr cafe_bbt_mirror_descr_2048 = {
         .len = 4,
         .veroffs = 18,
         .maxblocks = 4,
-        .pattern = cafe_mirror_pattern
+        .pattern = cafe_mirror_pattern_2048
 };
 
 static struct nand_ecclayout cafe_oobinfo_512 = {
@@ -419,6 +452,27 @@ static struct nand_ecclayout cafe_oobinfo_512 = {
         .oobfree = {{14, 2}}
 };
 
+static struct nand_bbt_descr cafe_bbt_main_descr_512 = {
+        .options = NAND_BBT_LASTBLOCK | NAND_BBT_CREATE | NAND_BBT_WRITE
+                | NAND_BBT_2BIT | NAND_BBT_VERSION | NAND_BBT_PERCHIP,
+        .offs = 14,
+        .len = 1,
+        .veroffs = 15,
+        .maxblocks = 4,
+        .pattern = cafe_bbt_pattern_512
+};
+
+static struct nand_bbt_descr cafe_bbt_mirror_descr_512 = {
+        .options = NAND_BBT_LASTBLOCK | NAND_BBT_CREATE | NAND_BBT_WRITE
+                | NAND_BBT_2BIT | NAND_BBT_VERSION | NAND_BBT_PERCHIP,
+        .offs = 14,
+        .len = 1,
+        .veroffs = 15,
+        .maxblocks = 4,
+        .pattern = cafe_mirror_pattern_512
+};
+
+
 static void cafe_nand_write_page_lowlevel(struct mtd_info *mtd,
                                           struct nand_chip *chip, const uint8_t *buf)
 {
@@ -566,19 +620,21 @@ static int __devinit cafe_nand_probe(struct pci_dev *pdev,
         ctrl |= 0x00007000;
         writel(ctrl | 0x05, cafe->mmio + 0x3004);
         writel(ctrl | 0x0a, cafe->mmio + 0x3004);
-        writel(0, cafe->mmio + 0x40);
+        writel(0, cafe->mmio + CAFE_NAND_DMA_CTRL);
 
         writel(0x7006, cafe->mmio + 0x3004);
         writel(0x700a, cafe->mmio + 0x3004);
 
         /* Set up DMA address */
-        writel(cafe->dmaaddr & 0xffffffff, cafe->mmio + 0x44);
+        writel(cafe->dmaaddr & 0xffffffff, cafe->mmio + CAFE_NAND_DMA_ADDR0);
         if (sizeof(cafe->dmaaddr) > 4)
-                writel((cafe->dmaaddr >> 16) >> 16, cafe->mmio + 0x48);
+                /* Shift in two parts to shut the compiler up */
+                writel((cafe->dmaaddr >> 16) >> 16, cafe->mmio + CAFE_NAND_DMA_ADDR1);
         else
-                writel(0, cafe->mmio + 0x48);
+                writel(0, cafe->mmio + CAFE_NAND_DMA_ADDR1);
+
         cafe_dev_dbg(&cafe->pdev->dev, "Set DMA address to %x (virt %p)\n",
-                readl(cafe->mmio+0x44), cafe->dmabuf);
+                readl(cafe->mmio + CAFE_NAND_DMA_ADDR0), cafe->dmabuf);
 
         /* Enable NAND IRQ in global IRQ mask register */
         writel(0x80000007, cafe->mmio + 0x300c);
@@ -620,27 +676,30 @@ static int __devinit cafe_nand_probe(struct pci_dev *pdev,
                 cafe->ctl2 |= 1<<29; /* 2KiB page size */
 
         /* Set up ECC according to the type of chip we found */
-        if (mtd->writesize == 512 || mtd->writesize == 2048) {
-                cafe->nand.ecc.mode = NAND_ECC_HW_SYNDROME;
-                cafe->nand.ecc.size = mtd->writesize;
-                cafe->nand.ecc.bytes = 14;
+        if (mtd->writesize == 2048) {
                 cafe->nand.ecc.layout = &cafe_oobinfo_2048;
                 cafe->nand.bbt_td = &cafe_bbt_main_descr_2048;
                 cafe->nand.bbt_md = &cafe_bbt_mirror_descr_2048;
-                cafe->nand.ecc.hwctl  = (void *)cafe_nand_bug;
-                cafe->nand.ecc.calculate = (void *)cafe_nand_bug;
-                cafe->nand.ecc.correct  = (void *)cafe_nand_bug;
-                cafe->nand.write_page = cafe_nand_write_page;
-                cafe->nand.ecc.write_page = cafe_nand_write_page_lowlevel;
-                cafe->nand.ecc.write_oob = cafe_nand_write_oob;
-                cafe->nand.ecc.read_page = cafe_nand_read_page;
-                cafe->nand.ecc.read_oob = cafe_nand_read_oob;
-
+        } else if (mtd->writesize == 512) {
+                cafe->nand.ecc.layout = &cafe_oobinfo_512;
+                cafe->nand.bbt_td = &cafe_bbt_main_descr_512;
+                cafe->nand.bbt_md = &cafe_bbt_mirror_descr_512;
         } else {
-                printk(KERN_WARNING "Unexpected NAND flash writesize %d. Using software ECC\n",
+                printk(KERN_WARNING "Unexpected NAND flash writesize %d. Aborting\n",
                        mtd->writesize);
-                cafe->nand.ecc.mode = NAND_ECC_NONE;
+                goto out_irq;
         }
+        cafe->nand.ecc.mode = NAND_ECC_HW_SYNDROME;
+        cafe->nand.ecc.size = mtd->writesize;
+        cafe->nand.ecc.bytes = 14;
+        cafe->nand.ecc.hwctl  = (void *)cafe_nand_bug;
+        cafe->nand.ecc.calculate = (void *)cafe_nand_bug;
+        cafe->nand.ecc.correct  = (void *)cafe_nand_bug;
+        cafe->nand.write_page = cafe_nand_write_page;
+        cafe->nand.ecc.write_page = cafe_nand_write_page_lowlevel;
+        cafe->nand.ecc.write_oob = cafe_nand_write_oob;
+        cafe->nand.ecc.read_page = cafe_nand_read_page;
+        cafe->nand.ecc.read_oob = cafe_nand_read_oob;
 
         err = nand_scan_tail(mtd);
         if (err)