mtd: nand: fix drivers abusing mtd->priv

The ->priv field of the mtd_info object attached to a nand_chip device
should point to the nand_chip device. The pxa and cafe drivers are
assigning this field their own private structure, which works fine as long
as the nand_chip field is the first one in the driver private struct but
seems a bit fragile.
Fix that by setting mtd->priv to point the nand_chip field and assigning
chip->priv to the private structure head.
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

drivers/mtd/nand/cafe_nand.c

@@ -101,7 +101,8 @@ static const char *part_probes[] = { "cmdlinepart", "RedBoot", NULL };
 
 static int cafe_device_ready(struct mtd_info *mtd)
 {
-	struct cafe_priv *cafe = mtd->priv;
+	struct nand_chip *chip = mtd->priv;
+	struct cafe_priv *cafe = chip->priv;
 	int result = !!(cafe_readl(cafe, NAND_STATUS) & 0x40000000);
 	uint32_t irqs = cafe_readl(cafe, NAND_IRQ);
 
@@ -117,7 +118,8 @@ static int cafe_device_ready(struct mtd_info *mtd)
 
 static void cafe_write_buf(struct mtd_info *mtd, const uint8_t *buf, int len)
 {
-	struct cafe_priv *cafe = mtd->priv;
+	struct nand_chip *chip = mtd->priv;
+	struct cafe_priv *cafe = chip->priv;
 
 	if (usedma)
 		memcpy(cafe->dmabuf + cafe->datalen, buf, len);
@@ -132,7 +134,8 @@ static void cafe_write_buf(struct mtd_info *mtd, const uint8_t *buf, int len)
 
 static void cafe_read_buf(struct mtd_info *mtd, uint8_t *buf, int len)
 {
-	struct cafe_priv *cafe = mtd->priv;
+	struct nand_chip *chip = mtd->priv;
+	struct cafe_priv *cafe = chip->priv;
 
 	if (usedma)
 		memcpy(buf, cafe->dmabuf + cafe->datalen, len);
@@ -146,7 +149,8 @@ static void cafe_read_buf(struct mtd_info *mtd, uint8_t *buf, int len)
 
 static uint8_t cafe_read_byte(struct mtd_info *mtd)
 {
-	struct cafe_priv *cafe = mtd->priv;
+	struct nand_chip *chip = mtd->priv;
+	struct cafe_priv *cafe = chip->priv;
 	uint8_t d;
 
 	cafe_read_buf(mtd, &d, 1);
@@ -158,7 +162,8 @@ static uint8_t cafe_read_byte(struct mtd_info *mtd)
 static void cafe_nand_cmdfunc(struct mtd_info *mtd, unsigned command,
 			      int column, int page_addr)
 {
-	struct cafe_priv *cafe = mtd->priv;
+	struct nand_chip *chip = mtd->priv;
+	struct cafe_priv *cafe = chip->priv;
 	int adrbytes = 0;
 	uint32_t ctl1;
 	uint32_t doneint = 0x80000000;
@@ -313,7 +318,8 @@ static void cafe_nand_cmdfunc(struct mtd_info *mtd, unsigned command,
 
 static void cafe_select_chip(struct mtd_info *mtd, int chipnr)
 {
-	struct cafe_priv *cafe = mtd->priv;
+	struct nand_chip *chip = mtd->priv;
+	struct cafe_priv *cafe = chip->priv;
 
 	cafe_dev_dbg(&cafe->pdev->dev, "select_chip %d\n", chipnr);
 
@@ -328,7 +334,8 @@ static void cafe_select_chip(struct mtd_info *mtd, int chipnr)
 static irqreturn_t cafe_nand_interrupt(int irq, void *id)
 {
 	struct mtd_info *mtd = id;
-	struct cafe_priv *cafe = mtd->priv;
+	struct nand_chip *chip = mtd->priv;
+	struct cafe_priv *cafe = chip->priv;
 	uint32_t irqs = cafe_readl(cafe, NAND_IRQ);
 	cafe_writel(cafe, irqs & ~0x90000000, NAND_IRQ);
 	if (!irqs)
@@ -377,7 +384,7 @@ static int cafe_nand_read_oob(struct mtd_info *mtd, struct nand_chip *chip,
 static int cafe_nand_read_page(struct mtd_info *mtd, struct nand_chip *chip,
 			       uint8_t *buf, int oob_required, int page)
 {
-	struct cafe_priv *cafe = mtd->priv;
+	struct cafe_priv *cafe = chip->priv;
 	unsigned int max_bitflips = 0;
 
 	cafe_dev_dbg(&cafe->pdev->dev, "ECC result %08x SYN1,2 %08x\n",
@@ -519,7 +526,7 @@ static int cafe_nand_write_page_lowlevel(struct mtd_info *mtd,
 					  const uint8_t *buf, int oob_required,
 					  int page)
 {
-	struct cafe_priv *cafe = mtd->priv;
+	struct cafe_priv *cafe = chip->priv;
 
 	chip->write_buf(mtd, buf, mtd->writesize);
 	chip->write_buf(mtd, chip->oob_poi, mtd->oobsize);
@@ -604,7 +611,8 @@ static int cafe_nand_probe(struct pci_dev *pdev,
 	cafe = (void *)(&mtd[1]);
 
 	mtd->dev.parent = &pdev->dev;
-	mtd->priv = cafe;
+	mtd->priv = &cafe->nand;
+	cafe->nand.priv = cafe;
 
 	cafe->pdev = pdev;
 	cafe->mmio = pci_iomap(pdev, 0, 0);
@@ -792,7 +800,8 @@ static int cafe_nand_probe(struct pci_dev *pdev,
 static void cafe_nand_remove(struct pci_dev *pdev)
 {
 	struct mtd_info *mtd = pci_get_drvdata(pdev);
-	struct cafe_priv *cafe = mtd->priv;
+	struct nand_chip *chip = mtd->priv;
+	struct cafe_priv *cafe = chip->priv;
 
 	/* Disable NAND IRQ in global IRQ mask register */
 	cafe_writel(cafe, ~1 & cafe_readl(cafe, GLOBAL_IRQ_MASK), GLOBAL_IRQ_MASK);
@@ -819,7 +828,8 @@ static int cafe_nand_resume(struct pci_dev *pdev)
 {
 	uint32_t ctrl;
 	struct mtd_info *mtd = pci_get_drvdata(pdev);
-	struct cafe_priv *cafe = mtd->priv;
+	struct nand_chip *chip = mtd->priv;
+	struct cafe_priv *cafe = chip->priv;
 
        /* Start off by resetting the NAND controller completely */
 	cafe_writel(cafe, 1, NAND_RESET);

drivers/mtd/nand/pxa3xx_nand.c

@@ -1113,7 +1113,8 @@ static int prepare_set_command(struct pxa3xx_nand_info *info, int command,
 static void nand_cmdfunc(struct mtd_info *mtd, unsigned command,
 			 int column, int page_addr)
 {
-	struct pxa3xx_nand_host *host = mtd->priv;
+	struct nand_chip *chip = mtd->priv;
+	struct pxa3xx_nand_host *host = chip->priv;
 	struct pxa3xx_nand_info *info = host->info_data;
 	int exec_cmd;
 
@@ -1161,7 +1162,8 @@ static void nand_cmdfunc_extended(struct mtd_info *mtd,
 				  const unsigned command,
 				  int column, int page_addr)
 {
-	struct pxa3xx_nand_host *host = mtd->priv;
+	struct nand_chip *chip = mtd->priv;
+	struct pxa3xx_nand_host *host = chip->priv;
 	struct pxa3xx_nand_info *info = host->info_data;
 	int exec_cmd, ext_cmd_type;
 
@@ -1281,7 +1283,7 @@ static int pxa3xx_nand_read_page_hwecc(struct mtd_info *mtd,
 		struct nand_chip *chip, uint8_t *buf, int oob_required,
 		int page)
 {
-	struct pxa3xx_nand_host *host = mtd->priv;
+	struct pxa3xx_nand_host *host = chip->priv;
 	struct pxa3xx_nand_info *info = host->info_data;
 
 	chip->read_buf(mtd, buf, mtd->writesize);
@@ -1307,7 +1309,8 @@ static int pxa3xx_nand_read_page_hwecc(struct mtd_info *mtd,
 
 static uint8_t pxa3xx_nand_read_byte(struct mtd_info *mtd)
 {
-	struct pxa3xx_nand_host *host = mtd->priv;
+	struct nand_chip *chip = mtd->priv;
+	struct pxa3xx_nand_host *host = chip->priv;
 	struct pxa3xx_nand_info *info = host->info_data;
 	char retval = 0xFF;
 
@@ -1320,7 +1323,8 @@ static uint8_t pxa3xx_nand_read_byte(struct mtd_info *mtd)
 
 static u16 pxa3xx_nand_read_word(struct mtd_info *mtd)
 {
-	struct pxa3xx_nand_host *host = mtd->priv;
+	struct nand_chip *chip = mtd->priv;
+	struct pxa3xx_nand_host *host = chip->priv;
 	struct pxa3xx_nand_info *info = host->info_data;
 	u16 retval = 0xFFFF;
 
@@ -1333,7 +1337,8 @@ static u16 pxa3xx_nand_read_word(struct mtd_info *mtd)
 
 static void pxa3xx_nand_read_buf(struct mtd_info *mtd, uint8_t *buf, int len)
 {
-	struct pxa3xx_nand_host *host = mtd->priv;
+	struct nand_chip *chip = mtd->priv;
+	struct pxa3xx_nand_host *host = chip->priv;
 	struct pxa3xx_nand_info *info = host->info_data;
 	int real_len = min_t(size_t, len, info->buf_count - info->buf_start);
 
@@ -1344,7 +1349,8 @@ static void pxa3xx_nand_read_buf(struct mtd_info *mtd, uint8_t *buf, int len)
 static void pxa3xx_nand_write_buf(struct mtd_info *mtd,
 		const uint8_t *buf, int len)
 {
-	struct pxa3xx_nand_host *host = mtd->priv;
+	struct nand_chip *chip = mtd->priv;
+	struct pxa3xx_nand_host *host = chip->priv;
 	struct pxa3xx_nand_info *info = host->info_data;
 	int real_len = min_t(size_t, len, info->buf_count - info->buf_start);
 
@@ -1359,7 +1365,8 @@ static void pxa3xx_nand_select_chip(struct mtd_info *mtd, int chip)
 
 static int pxa3xx_nand_waitfunc(struct mtd_info *mtd, struct nand_chip *this)
 {
-	struct pxa3xx_nand_host *host = mtd->priv;
+	struct nand_chip *chip = mtd->priv;
+	struct pxa3xx_nand_host *host = chip->priv;
 	struct pxa3xx_nand_info *info = host->info_data;
 
 	if (info->need_wait) {
@@ -1565,11 +1572,11 @@ static int pxa_ecc_init(struct pxa3xx_nand_info *info,
 
 static int pxa3xx_nand_scan(struct mtd_info *mtd)
 {
-	struct pxa3xx_nand_host *host = mtd->priv;
+	struct nand_chip *chip = mtd->priv;
+	struct pxa3xx_nand_host *host = chip->priv;
 	struct pxa3xx_nand_info *info = host->info_data;
 	struct platform_device *pdev = info->pdev;
 	struct pxa3xx_nand_platform_data *pdata = dev_get_platdata(&pdev->dev);
-	struct nand_chip *chip = mtd->priv;
 	int ret;
 	uint16_t ecc_strength, ecc_step;
 
@@ -1701,11 +1708,12 @@ static int alloc_nand_resource(struct platform_device *pdev)
 		host->mtd = mtd;
 		host->cs = cs;
 		host->info_data = info;
-		mtd->priv = host;
+		mtd->priv = chip;
 		mtd->dev.parent = &pdev->dev;
 		/* FIXME: all chips use the same device tree partitions */
 		nand_set_flash_node(chip, np);
 
+		chip->priv = host;
 		chip->ecc.read_page	= pxa3xx_nand_read_page_hwecc;
 		chip->ecc.write_page	= pxa3xx_nand_write_page_hwecc;
 		chip->controller        = &info->controller;