[MTD] OneNAND: add subpage write support

OneNAND supports up to 4 writes at one NAND page. Add support of this feature.

Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>

2 files changed, 44 insertions, 14 deletions

diff --git a/drivers/mtd/onenand/onenand_base.c b/drivers/mtd/onenand/onenand_base.c
index 3fab4d1b68bd..51fb84055ba3 100644
--- a/drivers/mtd/onenand/onenand_base.c
+++ b/drivers/mtd/onenand/onenand_base.c
@@ -192,8 +192,6 @@ static int onenand_command(struct mtd_info *mtd, int cmd, loff_t addr, size_t le
         struct onenand_chip *this = mtd->priv;
         int value, readcmd = 0, block_cmd = 0;
         int block, page;
-        /* Now we use page size operation */
-        int sectors = 4, count = 4;
 
         /* Address translation */
         switch (cmd) {
@@ -245,6 +243,8 @@ static int onenand_command(struct mtd_info *mtd, int cmd, loff_t addr, size_t le
         }
 
         if (page != -1) {
+                /* Now we use page size operation */
+                int sectors = 4, count = 4;
                 int dataram;
 
                 switch (cmd) {
@@ -914,6 +914,10 @@ static int onenand_verify_page(struct mtd_info *mtd, u_char *buf, loff_t addr)
         void __iomem *dataram0, *dataram1;
         int ret = 0;
 
+        /* In partial page write, just skip it */
+        if ((addr & (mtd->writesize - 1)) != 0)
+                return 0;
+
         this->command(mtd, ONENAND_CMD_READ, addr, mtd->writesize);
 
         ret = this->wait(mtd, FL_READING);
@@ -936,7 +940,7 @@ static int onenand_verify_page(struct mtd_info *mtd, u_char *buf, loff_t addr)
 #define onenand_verify_oob(...)         (0)
 #endif
 
-#define NOTALIGNED(x)   ((x & (mtd->writesize - 1)) != 0)
+#define NOTALIGNED(x)   ((x & (this->subpagesize - 1)) != 0)
 
 /**
  * onenand_write - [MTD Interface] write buffer to FLASH
@@ -954,6 +958,7 @@ static int onenand_write(struct mtd_info *mtd, loff_t to, size_t len,
         struct onenand_chip *this = mtd->priv;
         int written = 0;
         int ret = 0;
+        int column, subpage;
 
         DEBUG(MTD_DEBUG_LEVEL3, "onenand_write: to = 0x%08x, len = %i\n", (unsigned int) to, (int) len);
 
@@ -972,45 +977,61 @@ static int onenand_write(struct mtd_info *mtd, loff_t to, size_t len,
                 return -EINVAL;
         }
 
+        column = to & (mtd->writesize - 1);
+        subpage = column || (len & (mtd->writesize - 1));
+
         /* Grab the lock and see if the device is available */
         onenand_get_device(mtd, FL_WRITING);
 
         /* Loop until all data write */
         while (written < len) {
-                int thislen = min_t(int, mtd->writesize, len - written);
-
-                this->command(mtd, ONENAND_CMD_BUFFERRAM, to, mtd->writesize);
+                int bytes = mtd->writesize;
+                int thislen = min_t(int, bytes, len - written);
+                u_char *wbuf = (u_char *) buf;
+
+                this->command(mtd, ONENAND_CMD_BUFFERRAM, to, bytes);
+
+                /* Partial page write */
+                if (subpage) {
+                        bytes = min_t(int, bytes - column, (int) len);
+                        memset(this->page_buf, 0xff, mtd->writesize);
+                        memcpy(this->page_buf + column, buf, bytes);
+                        wbuf = this->page_buf;
+                        /* Even though partial write, we need page size */
+                        thislen = mtd->writesize;
+                }
 
-                this->write_bufferram(mtd, ONENAND_DATARAM, buf, 0, thislen);
+                this->write_bufferram(mtd, ONENAND_DATARAM, wbuf, 0, thislen);
                 this->write_bufferram(mtd, ONENAND_SPARERAM, ffchars, 0, mtd->oobsize);
 
                 this->command(mtd, ONENAND_CMD_PROG, to, mtd->writesize);
 
-                onenand_update_bufferram(mtd, to, 1);
+                /* In partial page write we don't update bufferram */
+                onenand_update_bufferram(mtd, to, !subpage);
 
                 ret = this->wait(mtd, FL_WRITING);
                 if (ret) {
                         DEBUG(MTD_DEBUG_LEVEL0, "onenand_write: write filaed %d\n", ret);
-                        goto out;
+                        break;
                 }
 
-                written += thislen;
-
                 /* Only check verify write turn on */
-                ret = onenand_verify_page(mtd, (u_char *) buf, to);
+                ret = onenand_verify_page(mtd, (u_char *) wbuf, to);
                 if (ret) {
                         DEBUG(MTD_DEBUG_LEVEL0, "onenand_write: verify failed %d\n", ret);
-                        goto out;
+                        break;
                 }
 
+                written += thislen;
+
                 if (written == len)
                         break;
 
+                column = 0;
                 to += thislen;
                 buf += thislen;
         }
 
-out:
         /* Deselect and wake up anyone waiting on the device */
         onenand_release_device(mtd);
 
@@ -2021,23 +2042,30 @@ int onenand_scan(struct mtd_info *mtd, int maxchips)
         init_waitqueue_head(&this->wq);
         spin_lock_init(&this->chip_lock);
 
+        /*
+         * Allow subpage writes up to oobsize.
+         */
         switch (mtd->oobsize) {
         case 64:
                 this->ecclayout = &onenand_oob_64;
+                mtd->subpage_sft = 2;
                 break;
 
         case 32:
                 this->ecclayout = &onenand_oob_32;
+                mtd->subpage_sft = 1;
                 break;
 
         default:
                 printk(KERN_WARNING "No OOB scheme defined for oobsize %d\n",
                         mtd->oobsize);
+                mtd->subpage_sft = 0;
                 /* To prevent kernel oops */
                 this->ecclayout = &onenand_oob_32;
                 break;
         }
 
+        this->subpagesize = mtd->writesize >> mtd->subpage_sft;
         mtd->ecclayout = this->ecclayout;
 
         /* Fill in remaining MTD driver data */
diff --git a/include/linux/mtd/onenand.h b/include/linux/mtd/onenand.h
index 62ca0f429822..fe3500d7d4bb 100644
--- a/include/linux/mtd/onenand.h
+++ b/include/linux/mtd/onenand.h
@@ -88,6 +88,7 @@ struct onenand_bufferram {
  *                      operation is in progress
  * @state:              [INTERN] the current state of the OneNAND device
  * @page_buf:           data buffer
+ * @subpagesize:        [INTERN] holds the subpagesize
  * @ecclayout:          [REPLACEABLE] the default ecc placement scheme
  * @bbm:                [REPLACEABLE] pointer to Bad Block Management
  * @priv:               [OPTIONAL] pointer to private chip date
@@ -128,6 +129,7 @@ struct onenand_chip {
         onenand_state_t         state;
         unsigned char           *page_buf;
 
+        int                     subpagesize;
         struct nand_ecclayout   *ecclayout;
 
         void                    *bbm;