mtd: bcm47xxsflash: writing support

Tested with BCM4706.

Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

1 files changed, 126 insertions, 4 deletions

diff --git a/drivers/mtd/devices/bcm47xxsflash.c b/drivers/mtd/devices/bcm47xxsflash.c
index 534cb741b107..77de29bc02ba 100644
--- a/drivers/mtd/devices/bcm47xxsflash.c
+++ b/drivers/mtd/devices/bcm47xxsflash.c
@@ -116,6 +116,127 @@ static int bcm47xxsflash_read(struct mtd_info *mtd, loff_t from, size_t len,
         return len;
 }
 
+static int bcm47xxsflash_write_st(struct mtd_info *mtd, u32 offset, size_t len,
+                                  const u_char *buf)
+{
+        struct bcm47xxsflash *b47s = mtd->priv;
+        int written = 0;
+
+        /* Enable writes */
+        bcm47xxsflash_cmd(b47s, OPCODE_ST_WREN);
+
+        /* Write first byte */
+        b47s->cc_write(b47s, BCMA_CC_FLASHADDR, offset);
+        b47s->cc_write(b47s, BCMA_CC_FLASHDATA, *buf++);
+
+        /* Program page */
+        if (b47s->bcma_cc->core->id.rev < 20) {
+                bcm47xxsflash_cmd(b47s, OPCODE_ST_PP);
+                return 1; /* 1B written */
+        }
+
+        /* Program page and set CSA (on newer chips we can continue writing) */
+        bcm47xxsflash_cmd(b47s, OPCODE_ST_CSA | OPCODE_ST_PP);
+        offset++;
+        len--;
+        written++;
+
+        while (len > 0) {
+                /* Page boundary, another function call is needed */
+                if ((offset & 0xFF) == 0)
+                        break;
+
+                bcm47xxsflash_cmd(b47s, OPCODE_ST_CSA | *buf++);
+                offset++;
+                len--;
+                written++;
+        }
+
+        /* All done, drop CSA & poll */
+        b47s->cc_write(b47s, BCMA_CC_FLASHCTL, 0);
+        udelay(1);
+        if (bcm47xxsflash_poll(b47s, HZ / 10))
+                pr_err("Flash rejected dropping CSA\n");
+
+        return written;
+}
+
+static int bcm47xxsflash_write_at(struct mtd_info *mtd, u32 offset, size_t len,
+                                  const u_char *buf)
+{
+        struct bcm47xxsflash *b47s = mtd->priv;
+        u32 mask = b47s->blocksize - 1;
+        u32 page = (offset & ~mask) << 1;
+        u32 byte = offset & mask;
+        int written = 0;
+
+        /* If we don't overwrite whole page, read it to the buffer first */
+        if (byte || (len < b47s->blocksize)) {
+                int err;
+
+                b47s->cc_write(b47s, BCMA_CC_FLASHADDR, page);
+                bcm47xxsflash_cmd(b47s, OPCODE_AT_BUF1_LOAD);
+                /* 250 us for AT45DB321B */
+                err = bcm47xxsflash_poll(b47s, HZ / 1000);
+                if (err) {
+                        pr_err("Timeout reading page 0x%X info buffer\n", page);
+                        return err;
+                }
+        }
+
+        /* Change buffer content with our data */
+        while (len > 0) {
+                /* Page boundary, another function call is needed */
+                if (byte == b47s->blocksize)
+                        break;
+
+                b47s->cc_write(b47s, BCMA_CC_FLASHADDR, byte++);
+                b47s->cc_write(b47s, BCMA_CC_FLASHDATA, *buf++);
+                bcm47xxsflash_cmd(b47s, OPCODE_AT_BUF1_WRITE);
+                len--;
+                written++;
+        }
+
+        /* Program page with the buffer content */
+        b47s->cc_write(b47s, BCMA_CC_FLASHADDR, page);
+        bcm47xxsflash_cmd(b47s, OPCODE_AT_BUF1_PROGRAM);
+
+        return written;
+}
+
+static int bcm47xxsflash_write(struct mtd_info *mtd, loff_t to, size_t len,
+                               size_t *retlen, const u_char *buf)
+{
+        struct bcm47xxsflash *b47s = mtd->priv;
+        int written;
+
+        /* Writing functions can return without writing all passed data, for
+         * example when the hardware is too old or when we git page boundary.
+         */
+        while (len > 0) {
+                switch (b47s->type) {
+                case BCM47XXSFLASH_TYPE_ST:
+                        written = bcm47xxsflash_write_st(mtd, to, len, buf);
+                        break;
+                case BCM47XXSFLASH_TYPE_ATMEL:
+                        written = bcm47xxsflash_write_at(mtd, to, len, buf);
+                        break;
+                default:
+                        BUG_ON(1);
+                }
+                if (written < 0) {
+                        pr_err("Error writing at offset 0x%llX\n", to);
+                        return written;
+                }
+                to += (loff_t)written;
+                len -= written;
+                *retlen += written;
+                buf += written;
+        }
+
+        return 0;
+}
+
 static void bcm47xxsflash_fill_mtd(struct bcm47xxsflash *b47s)
 {
         struct mtd_info *mtd = &b47s->mtd;
@@ -123,16 +244,17 @@ static void bcm47xxsflash_fill_mtd(struct bcm47xxsflash *b47s)
         mtd->priv = b47s;
         mtd->name = "bcm47xxsflash";
         mtd->owner = THIS_MODULE;
-        mtd->type = MTD_ROM;
 
-        /* TODO: implement writing support and verify/change following code */
-        mtd->flags = MTD_CAP_ROM;
+        mtd->type = MTD_NORFLASH;
+        mtd->flags = MTD_CAP_NORFLASH;
         mtd->size = b47s->size;
         mtd->erasesize = b47s->blocksize;
-        mtd->writebufsize = mtd->writesize = 1;
+        mtd->writesize = 1;
+        mtd->writebufsize = 1;
 
         mtd->_erase = bcm47xxsflash_erase;
         mtd->_read = bcm47xxsflash_read;
+        mtd->_write = bcm47xxsflash_write;
 }
 
 /**************************************************