mtd: nand: kill the the NAND_MAX_PAGESIZE/NAND_MAX_OOBSIZE for nand_buffers{}

The patch converts the arrays to buffer pointers for nand_buffers{}.

The cafe_nand.c is the only NAND_OWN_BUFFERS user which allocates
nand_buffers{} itself.

This patch disables the DMA for nand_scan_ident, and restores the DMA
status after we finish the nand_scan_ident. This way, we can get page
size and OOB size and use them to allocate cafe->dmabuf.

Since the cafe_nand.c uses the NAND_ECC_HW_SYNDROME ECC mode, we do not
allocate the buffers for @ecccalc and @ecccode.

Signed-off-by: Huang Shijie <b32955@freescale.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

3 files changed, 67 insertions, 32 deletions

diff --git a/drivers/mtd/nand/cafe_nand.c b/drivers/mtd/nand/cafe_nand.c
index f2f64addb5e8..4e66726da9aa 100644
--- a/drivers/mtd/nand/cafe_nand.c
+++ b/drivers/mtd/nand/cafe_nand.c
@@ -627,6 +627,8 @@ static int cafe_nand_probe(struct pci_dev *pdev,
         struct cafe_priv *cafe;
         uint32_t ctrl;
         int err = 0;
+        int old_dma;
+        struct nand_buffers *nbuf;
 
         /* Very old versions shared the same PCI ident for all three
            functions on the chip. Verify the class too... */
@@ -655,13 +657,6 @@ static int cafe_nand_probe(struct pci_dev *pdev,
                 err = -ENOMEM;
                 goto out_free_mtd;
         }
-        cafe->dmabuf = dma_alloc_coherent(&cafe->pdev->dev, 2112 + sizeof(struct nand_buffers),
-                                          &cafe->dmaaddr, GFP_KERNEL);
-        if (!cafe->dmabuf) {
-                err = -ENOMEM;
-                goto out_ior;
-        }
-        cafe->nand.buffers = (void *)cafe->dmabuf + 2112;
 
         cafe->rs = init_rs_non_canonical(12, &cafe_mul, 0, 1, 8);
         if (!cafe->rs) {
@@ -721,7 +716,7 @@ static int cafe_nand_probe(struct pci_dev *pdev,
                           "CAFE NAND", mtd);
         if (err) {
                 dev_warn(&pdev->dev, "Could not register IRQ %d\n", pdev->irq);
-                goto out_free_dma;
+                goto out_ior;
         }
 
         /* Disable master reset, enable NAND clock */
@@ -735,6 +730,32 @@ static int cafe_nand_probe(struct pci_dev *pdev,
         cafe_writel(cafe, 0x7006, GLOBAL_CTRL);
         cafe_writel(cafe, 0x700a, GLOBAL_CTRL);
 
+        /* Enable NAND IRQ in global IRQ mask register */
+        cafe_writel(cafe, 0x80000007, GLOBAL_IRQ_MASK);
+        cafe_dev_dbg(&cafe->pdev->dev, "Control %x, IRQ mask %x\n",
+                cafe_readl(cafe, GLOBAL_CTRL),
+                cafe_readl(cafe, GLOBAL_IRQ_MASK));
+
+        /* Do not use the DMA for the nand_scan_ident() */
+        old_dma = usedma;
+        usedma = 0;
+
+        /* Scan to find existence of the device */
+        if (nand_scan_ident(mtd, 2, NULL)) {
+                err = -ENXIO;
+                goto out_irq;
+        }
+
+        cafe->dmabuf = dma_alloc_coherent(&cafe->pdev->dev,
+                                2112 + sizeof(struct nand_buffers) +
+                                mtd->writesize + mtd->oobsize,
+                                &cafe->dmaaddr, GFP_KERNEL);
+        if (!cafe->dmabuf) {
+                err = -ENOMEM;
+                goto out_irq;
+        }
+        cafe->nand.buffers = nbuf = (void *)cafe->dmabuf + 2112;
+
         /* Set up DMA address */
         cafe_writel(cafe, cafe->dmaaddr & 0xffffffff, NAND_DMA_ADDR0);
         if (sizeof(cafe->dmaaddr) > 4)
@@ -746,16 +767,13 @@ static int cafe_nand_probe(struct pci_dev *pdev,
         cafe_dev_dbg(&cafe->pdev->dev, "Set DMA address to %x (virt %p)\n",
                 cafe_readl(cafe, NAND_DMA_ADDR0), cafe->dmabuf);
 
-        /* Enable NAND IRQ in global IRQ mask register */
-        cafe_writel(cafe, 0x80000007, GLOBAL_IRQ_MASK);
-        cafe_dev_dbg(&cafe->pdev->dev, "Control %x, IRQ mask %x\n",
-                cafe_readl(cafe, GLOBAL_CTRL), cafe_readl(cafe, GLOBAL_IRQ_MASK));
+        /* this driver does not need the @ecccalc and @ecccode */
+        nbuf->ecccalc = NULL;
+        nbuf->ecccode = NULL;
+        nbuf->databuf = (uint8_t *)(nbuf + 1);
 
-        /* Scan to find existence of the device */
-        if (nand_scan_ident(mtd, 2, NULL)) {
-                err = -ENXIO;
-                goto out_irq;
-        }
+        /* Restore the DMA flag */
+        usedma = old_dma;
 
         cafe->ctl2 = 1<<27; /* Reed-Solomon ECC */
         if (mtd->writesize == 2048)
@@ -773,7 +791,7 @@ static int cafe_nand_probe(struct pci_dev *pdev,
         } else {
                 printk(KERN_WARNING "Unexpected NAND flash writesize %d. Aborting\n",
                        mtd->writesize);
-                goto out_irq;
+                goto out_free_dma;
         }
         cafe->nand.ecc.mode = NAND_ECC_HW_SYNDROME;
         cafe->nand.ecc.size = mtd->writesize;
@@ -790,7 +808,7 @@ static int cafe_nand_probe(struct pci_dev *pdev,
 
         err = nand_scan_tail(mtd);
         if (err)
-                goto out_irq;
+                goto out_free_dma;
 
         pci_set_drvdata(pdev, mtd);
 
@@ -799,12 +817,15 @@ static int cafe_nand_probe(struct pci_dev *pdev,
 
         goto out;
 
+ out_free_dma:
+        dma_free_coherent(&cafe->pdev->dev,
+                        2112 + sizeof(struct nand_buffers) +
+                        mtd->writesize + mtd->oobsize,
+                        cafe->dmabuf, cafe->dmaaddr);
  out_irq:
         /* Disable NAND IRQ in global IRQ mask register */
         cafe_writel(cafe, ~1 & cafe_readl(cafe, GLOBAL_IRQ_MASK), GLOBAL_IRQ_MASK);
         free_irq(pdev->irq, mtd);
- out_free_dma:
-        dma_free_coherent(&cafe->pdev->dev, 2112, cafe->dmabuf, cafe->dmaaddr);
  out_ior:
         pci_iounmap(pdev, cafe->mmio);
  out_free_mtd:
@@ -824,7 +845,10 @@ static void cafe_nand_remove(struct pci_dev *pdev)
         nand_release(mtd);
         free_rs(cafe->rs);
         pci_iounmap(pdev, cafe->mmio);
-        dma_free_coherent(&cafe->pdev->dev, 2112, cafe->dmabuf, cafe->dmaaddr);
+        dma_free_coherent(&cafe->pdev->dev,
+                        2112 + sizeof(struct nand_buffers) +
+                        mtd->writesize + mtd->oobsize,
+                        cafe->dmabuf, cafe->dmaaddr);
         kfree(mtd);
 }
 
diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index 9715a7ba164a..deeaa1cc4a85 100644
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -3696,15 +3696,26 @@ int nand_scan_tail(struct mtd_info *mtd)
         int i;
         struct nand_chip *chip = mtd->priv;
         struct nand_ecc_ctrl *ecc = &chip->ecc;
+        struct nand_buffers *nbuf;
 
         /* New bad blocks should be marked in OOB, flash-based BBT, or both */
         BUG_ON((chip->bbt_options & NAND_BBT_NO_OOB_BBM) &&
                         !(chip->bbt_options & NAND_BBT_USE_FLASH));
 
-        if (!(chip->options & NAND_OWN_BUFFERS))
-                chip->buffers = kmalloc(sizeof(*chip->buffers), GFP_KERNEL);
-        if (!chip->buffers)
-                return -ENOMEM;
+        if (!(chip->options & NAND_OWN_BUFFERS)) {
+                nbuf = kzalloc(sizeof(*nbuf) + mtd->writesize
+                                + mtd->oobsize * 3, GFP_KERNEL);
+                if (!nbuf)
+                        return -ENOMEM;
+                nbuf->ecccalc = (uint8_t *)(nbuf + 1);
+                nbuf->ecccode = nbuf->ecccalc + mtd->oobsize;
+                nbuf->databuf = nbuf->ecccode + mtd->oobsize;
+
+                chip->buffers = nbuf;
+        } else {
+                if (!chip->buffers)
+                        return -ENOMEM;
+        }
 
         /* Set the internal oob buffer location, just after the page data */
         chip->oob_poi = chip->buffers->databuf + mtd->writesize;
diff --git a/include/linux/mtd/nand.h b/include/linux/mtd/nand.h
index 32f8612469d8..520ebca11f5d 100644
--- a/include/linux/mtd/nand.h
+++ b/include/linux/mtd/nand.h
@@ -435,17 +435,17 @@ struct nand_ecc_ctrl {
 
 /**
  * struct nand_buffers - buffer structure for read/write
- * @ecccalc:    buffer for calculated ECC
- * @ecccode:    buffer for ECC read from flash
- * @databuf:    buffer for data - dynamically sized
+ * @ecccalc:    buffer pointer for calculated ECC, size is oobsize.
+ * @ecccode:    buffer pointer for ECC read from flash, size is oobsize.
+ * @databuf:    buffer pointer for data, size is (page size + oobsize).
  *
  * Do not change the order of buffers. databuf and oobrbuf must be in
  * consecutive order.
  */
 struct nand_buffers {
-        uint8_t ecccalc[NAND_MAX_OOBSIZE];
-        uint8_t ecccode[NAND_MAX_OOBSIZE];
-        uint8_t databuf[NAND_MAX_PAGESIZE + NAND_MAX_OOBSIZE];
+        uint8_t *ecccalc;
+        uint8_t *ecccode;
+        uint8_t *databuf;
 };
 
 /**