mtd: nand: refactor erase_cmd() to return chip status

The nand_chip::erase_cmd callback previously served a dual purpose; for
one, it allowed a per-flash-chip override, so that AG-AND devices could
use a different erase command than other NAND. These AND devices were
dropped in commit 14c6578683367b1e7af0c3c09e872b45a45183a7 (mtd: nand:
remove AG-AND support). On the other hand, some drivers (denali and
doc-g4) need to use this sort of callback to implement
controller-specific erase operations.

To make the latter operation easier for some drivers (e.g., ST's new BCH
NAND driver), it helps if the command dispatch and wait functions can be
lumped together, rather than called separately.

This patch does two things:
1. Pull the call to chip->waitfunc() into chip->erase_cmd(), and return
the status from this callback
2. Rename erase_cmd() to just erase(), since this callback does a
little more than just send a command

Signed-off-by: Brian Norris <[e-mail]>
Tested-by: Lee Jones <[e-mail]>

drivers/mtd/nand/denali.c

···
 	return status;
 }
 
-static void denali_erase(struct mtd_info *mtd, int page)
+static int denali_erase(struct mtd_info *mtd, int page)
 {
 	struct denali_nand_info *denali = mtd_to_denali(mtd);
 
···
 	irq_status = wait_for_irq(denali, INTR_STATUS__ERASE_COMP |
 					INTR_STATUS__ERASE_FAIL);
 
-	denali->status = (irq_status & INTR_STATUS__ERASE_FAIL) ?
-						NAND_STATUS_FAIL : PASS;
+	return (irq_status & INTR_STATUS__ERASE_FAIL) ? NAND_STATUS_FAIL : PASS;
 }
 
 static void denali_cmdfunc(struct mtd_info *mtd, unsigned int cmd, int col,
···
 	denali->nand.ecc.write_page_raw = denali_write_page_raw;
 	denali->nand.ecc.read_oob = denali_read_oob;
 	denali->nand.ecc.write_oob = denali_write_oob;
-	denali->nand.erase_cmd = denali_erase;
+	denali->nand.erase = denali_erase;
 
 	if (nand_scan_tail(&denali->mtd)) {
 		ret = -ENXIO;

drivers/mtd/nand/docg4.c

···
 	return 0;
 }
 
-static void docg4_erase_block(struct mtd_info *mtd, int page)
+static int docg4_erase_block(struct mtd_info *mtd, int page)
 {
 	struct nand_chip *nand = mtd->priv;
 	struct docg4_priv *doc = nand->priv;
···
 	write_nop(docptr);
 	poll_status(doc);
 	write_nop(docptr);
+
+	return nand->waitfunc(mtd, nand);
 }
 
 static int write_page(struct mtd_info *mtd, struct nand_chip *nand,
···
 	nand->block_markbad = docg4_block_markbad;
 	nand->read_buf = docg4_read_buf;
 	nand->write_buf = docg4_write_buf16;
-	nand->erase_cmd = docg4_erase_block;
+	nand->erase = docg4_erase_block;
 	nand->ecc.read_page = docg4_read_page;
 	nand->ecc.write_page = docg4_write_page;
 	nand->ecc.read_page_raw = docg4_read_page_raw;

drivers/mtd/nand/nand_base.c

···
 }
 
 /**
- * single_erase_cmd - [GENERIC] NAND standard block erase command function
+ * single_erase - [GENERIC] NAND standard block erase command function
  * @mtd: MTD device structure
  * @page: the page address of the block which will be erased
  *
- * Standard erase command for NAND chips.
+ * Standard erase command for NAND chips. Returns NAND status.
  */
-static void single_erase_cmd(struct mtd_info *mtd, int page)
+static int single_erase(struct mtd_info *mtd, int page)
 {
 	struct nand_chip *chip = mtd->priv;
 	/* Send commands to erase a block */
 	chip->cmdfunc(mtd, NAND_CMD_ERASE1, -1, page);
 	chip->cmdfunc(mtd, NAND_CMD_ERASE2, -1, -1);
+
+	return chip->waitfunc(mtd, chip);
 }
 
 /**
···
 		    (page + pages_per_block))
 			chip->pagebuf = -1;
 
-		chip->erase_cmd(mtd, page & chip->pagemask);
-
-		status = chip->waitfunc(mtd, chip);
+		status = chip->erase(mtd, page & chip->pagemask);
 
 		/*
 		 * See if operation failed and additional status checks are
···
 	}
 
 	chip->badblockbits = 8;
-	chip->erase_cmd = single_erase_cmd;
+	chip->erase = single_erase;
 
 	/* Do not replace user supplied command function! */
 	if (mtd->writesize > 512 && chip->cmdfunc == nand_command)

include/linux/mtd/nand.h

···
  * @ecc:		[BOARDSPECIFIC] ECC control structure
  * @buffers:		buffer structure for read/write
  * @hwcontrol:		platform-specific hardware control structure
- * @erase_cmd:		[INTERN] erase command write function, selectable due
- *			to AND support.
+ * @erase:		[REPLACEABLE] erase function
  * @scan_bbt:		[REPLACEABLE] function to scan bad block table
  * @chip_delay:		[BOARDSPECIFIC] chip dependent delay for transferring
  *			data from array to read regs (tR).
···
 	void (*cmdfunc)(struct mtd_info *mtd, unsigned command, int column,
 			int page_addr);
 	int(*waitfunc)(struct mtd_info *mtd, struct nand_chip *this);
-	void (*erase_cmd)(struct mtd_info *mtd, int page);
+	int (*erase)(struct mtd_info *mtd, int page);
 	int (*scan_bbt)(struct mtd_info *mtd);
 	int (*errstat)(struct mtd_info *mtd, struct nand_chip *this, int state,
 			int status, int page);