Index: mx25l.c
===================================================================
--- mx25l.c	(revision 210265)
+++ mx25l.c	(working copy)
@@ -70,6 +70,10 @@
 	struct proc	*sc_p;
 	struct bio_queue_head sc_bio_queue;
 	unsigned int	sc_flags;
+	struct {
+		unsigned int	size;
+		uint8_t		cmd;
+	} sc_erase;
 };
 
 #define M25PXX_LOCK(_sc)		mtx_lock(&(_sc)->sc_mtx)
@@ -208,6 +212,9 @@
 	err = SPIBUS_TRANSFER(device_get_parent(dev), dev, &cmd);
 }
 
+/*
+ * Implement "replace" write - ie, erase/write
+ */
 static int
 mx25l_write(device_t dev, off_t offset, caddr_t data, off_t count)
 {
@@ -228,26 +235,14 @@
 	bytes_writen = 0;
 	write_offset = offset;
 
-	/*
-	 * Sanity checks
-	 */
-	KASSERT(count % sc->sc_sectorsize == 0,
-	    ("count for BIO_WRITE is not sector size (%d bytes) aligned",
-		sc->sc_sectorsize));
+	/* Minimum write size is (currently) minimum erase size */
+	if ((count % sc->sc_erase.size != 0) || (offset % sc->sc_erase.size != 0))
+		return EIO;
+	/* IO size for now must also be complete FLASH_PAGE_SIZE'd chunks too */
+	if ((count % FLASH_PAGE_SIZE != 0) || (offset % FLASH_PAGE_SIZE != 0))
+		return EIO;
 
-	KASSERT(offset % sc->sc_sectorsize == 0,
-	    ("offset for BIO_WRITE is not sector size (%d bytes) aligned",
-		sc->sc_sectorsize));
-
 	/*
-	 * Assume here that we write per-sector only 
-	 * and sector size should be 256 bytes aligned
-	 */
-	KASSERT(write_offset % FLASH_PAGE_SIZE == 0,
-	    ("offset for BIO_WRITE is not page size (%d bytes) aligned",
-		FLASH_PAGE_SIZE));
-
-	/*
 	 * Maximum write size for CMD_PAGE_PROGRAM is 
 	 * FLASH_PAGE_SIZE, so split data to chunks 
 	 * FLASH_PAGE_SIZE bytes eash and write them
@@ -258,7 +253,7 @@
 		 * If we crossed sector boundary - erase next sector
 		 */
 		if (((offset + bytes_writen) % sc->sc_sectorsize) == 0)
-			mx25l_erase_cmd(dev, offset + bytes_writen, CMD_SECTOR_ERASE);
+			mx25l_erase_cmd(dev, offset + bytes_writen, sc->sc_erase.cmd);
 
 		txBuf[0] = CMD_PAGE_PROGRAM;
 		txBuf[1] = ((write_offset >> 16) & 0xff);
@@ -305,17 +300,6 @@
 	pdev = device_get_parent(dev);
 	sc = device_get_softc(dev);
 
-	/*
-	 * Sanity checks
-	 */
-	KASSERT(count % sc->sc_sectorsize == 0,
-	    ("count for BIO_READ is not sector size (%d bytes) aligned",
-		sc->sc_sectorsize));
-
-	KASSERT(offset % sc->sc_sectorsize == 0,
-	    ("offset for BIO_READ is not sector size (%d bytes) aligned",
-		sc->sc_sectorsize));
-
 	txBuf[0] = CMD_FAST_READ;
 	cmd.tx_cmd_sz = 5;
 	cmd.rx_cmd_sz = 5;
@@ -377,6 +361,18 @@
 	sc->sc_sectorsize =  ident->sectorsize;
 	sc->sc_flags = ident->flags;
 
+	/* Support 4k/32k erases if possible */
+	if (ident->flags & FL_ERASE_4K) {
+		sc->sc_erase.size = 4096;
+		sc->sc_erase.cmd = CMD_BLOCK_4K_ERASE;
+	} else if (ident->flags & FL_ERASE_32K) {
+		sc->sc_erase.size = 32768;
+		sc->sc_erase.cmd = CMD_BLOCK_32K_ERASE;
+	} else {
+		sc->sc_erase.size = ident->sectorsize;
+		sc->sc_erase.cmd = CMD_SECTOR_ERASE;
+	}
+
         /* NB: use stripesize to hold the erase/region size for RedBoot */
 	sc->sc_disk->d_stripesize = ident->sectorsize;