mtd: nand: provide valid ->data_interface during NAND detection

Right now, the chip->data_interface field is populated in
nand_scan_tail(), so after the whole NAND detection has taken place.
This is fine because these timings are not yet used by the core so
early in the probe process, but the situation is about to change with
the introduction of ->exec_op().

Also, by convention, nand_scan_ident() is not supposed to allocate
resources, only nand_scan_tail() can, so this prevent us from
allocating and initializing the data_interface object in
nand_scan_ident().

In order to solve this problem, directly embed a data_interface object
in nand_chip so that we don't have to allocate it, and initialize it to
ONFI SDR mode 0 at the very beginning of nand_scan_ident().
Signed-off-by: Miquel Raynal <miquel.raynal@free-electrons.com>
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>

drivers/mtd/nand/nand_base.c

@@ -816,8 +816,8 @@ static void nand_ccs_delay(struct nand_chip *chip)
 	 * Wait tCCS_min if it is correctly defined, otherwise wait 500ns
 	 * (which should be safe for all NANDs).
 	 */
-	if (chip->data_interface && chip->data_interface->timings.sdr.tCCS_min)
-		ndelay(chip->data_interface->timings.sdr.tCCS_min / 1000);
+	if (chip->setup_data_interface)
+		ndelay(chip->data_interface.timings.sdr.tCCS_min / 1000);
 	else
 		ndelay(500);
 }
@@ -1112,7 +1112,6 @@ static int nand_wait(struct mtd_info *mtd, struct nand_chip *chip)
 static int nand_reset_data_interface(struct nand_chip *chip, int chipnr)
 {
 	struct mtd_info *mtd = nand_to_mtd(chip);
-	const struct nand_data_interface *conf;
 	int ret;
 
 	if (!chip->setup_data_interface)
@@ -1132,8 +1131,8 @@ static int nand_reset_data_interface(struct nand_chip *chip, int chipnr)
 	 * timings to timing mode 0.
 	 */
 
-	conf = nand_get_default_data_interface();
-	ret = chip->setup_data_interface(mtd, chipnr, conf);
+	onfi_fill_data_interface(chip, NAND_SDR_IFACE, 0);
+	ret = chip->setup_data_interface(mtd, chipnr, &chip->data_interface);
 	if (ret)
 		pr_err("Failed to configure data interface to SDR timing mode 0\n");
 
@@ -1158,7 +1157,7 @@ static int nand_setup_data_interface(struct nand_chip *chip, int chipnr)
 	struct mtd_info *mtd = nand_to_mtd(chip);
 	int ret;
 
-	if (!chip->setup_data_interface || !chip->data_interface)
+	if (!chip->setup_data_interface)
 		return 0;
 
 	/*
@@ -1179,7 +1178,7 @@ static int nand_setup_data_interface(struct nand_chip *chip, int chipnr)
 			goto err;
 	}
 
-	ret = chip->setup_data_interface(mtd, chipnr, chip->data_interface);
+	ret = chip->setup_data_interface(mtd, chipnr, &chip->data_interface);
 err:
 	return ret;
 }
@@ -1219,21 +1218,16 @@ static int nand_init_data_interface(struct nand_chip *chip)
 		modes = GENMASK(chip->onfi_timing_mode_default, 0);
 	}
 
-	chip->data_interface = kzalloc(sizeof(*chip->data_interface),
-				       GFP_KERNEL);
-	if (!chip->data_interface)
-		return -ENOMEM;
 
 	for (mode = fls(modes) - 1; mode >= 0; mode--) {
-		ret = onfi_init_data_interface(chip, chip->data_interface,
-					       NAND_SDR_IFACE, mode);
+		ret = onfi_fill_data_interface(chip, NAND_SDR_IFACE, mode);
 		if (ret)
 			continue;
 
 		/* Pass -1 to only */
 		ret = chip->setup_data_interface(mtd,
 						 NAND_DATA_IFACE_CHECK_ONLY,
-						 chip->data_interface);
+						 &chip->data_interface);
 		if (!ret) {
 			chip->onfi_timing_mode_default = mode;
 			break;
@@ -1243,11 +1237,6 @@ static int nand_init_data_interface(struct nand_chip *chip)
 	return 0;
 }
 
-static void nand_release_data_interface(struct nand_chip *chip)
-{
-	kfree(chip->data_interface);
-}
-
 /**
  * nand_read_page_op - Do a READ PAGE operation
  * @chip: The NAND chip
@@ -1763,11 +1752,16 @@ EXPORT_SYMBOL_GPL(nand_write_data_op);
  * @chip: The NAND chip
  * @chipnr: Internal die id
  *
- * Returns 0 for success or negative error code otherwise
+ * Save the timings data structure, then apply SDR timings mode 0 (see
+ * nand_reset_data_interface for details), do the reset operation, and
+ * apply back the previous timings.
+ *
+ * Returns 0 on success, a negative error code otherwise.
  */
 int nand_reset(struct nand_chip *chip, int chipnr)
 {
 	struct mtd_info *mtd = nand_to_mtd(chip);
+	struct nand_data_interface saved_data_intf = chip->data_interface;
 	int ret;
 
 	ret = nand_reset_data_interface(chip, chipnr);
@@ -1785,6 +1779,7 @@ int nand_reset(struct nand_chip *chip, int chipnr)
 		return ret;
 
 	chip->select_chip(mtd, chipnr);
+	chip->data_interface = saved_data_intf;
 	ret = nand_setup_data_interface(chip, chipnr);
 	chip->select_chip(mtd, -1);
 	if (ret)
@@ -4889,6 +4884,9 @@ int nand_scan_ident(struct mtd_info *mtd, int maxchips,
 	struct nand_chip *chip = mtd_to_nand(mtd);
 	int ret;
 
+	/* Enforce the right timings for reset/detection */
+	onfi_fill_data_interface(chip, NAND_SDR_IFACE, 0);
+
 	ret = nand_dt_init(chip);
 	if (ret)
 		return ret;
@@ -5629,7 +5627,7 @@ int nand_scan_tail(struct mtd_info *mtd)
 		chip->select_chip(mtd, -1);
 
 		if (ret)
-			goto err_nand_data_iface_cleanup;
+			goto err_nand_manuf_cleanup;
 	}
 
 	/* Check, if we should skip the bad block table scan */
@@ -5639,12 +5637,10 @@ int nand_scan_tail(struct mtd_info *mtd)
 	/* Build bad block table */
 	ret = chip->scan_bbt(mtd);
 	if (ret)
-		goto err_nand_data_iface_cleanup;
+		goto err_nand_manuf_cleanup;
 
 	return 0;
 
-err_nand_data_iface_cleanup:
-	nand_release_data_interface(chip);
 
 err_nand_manuf_cleanup:
 	nand_manufacturer_cleanup(chip);
@@ -5703,8 +5699,6 @@ void nand_cleanup(struct nand_chip *chip)
 	    chip->ecc.algo == NAND_ECC_BCH)
 		nand_bch_free((struct nand_bch_control *)chip->ecc.priv);
 
-	nand_release_data_interface(chip);
-
 	/* Free bad block table memory */
 	kfree(chip->bbt);
 	if (!(chip->options & NAND_OWN_BUFFERS) && chip->buffers) {

drivers/mtd/nand/nand_timings.c

@@ -283,16 +283,16 @@ const struct nand_sdr_timings *onfi_async_timing_mode_to_sdr_timings(int mode)
 EXPORT_SYMBOL(onfi_async_timing_mode_to_sdr_timings);
 
 /**
- * onfi_init_data_interface - [NAND Interface] Initialize a data interface from
+ * onfi_fill_data_interface - [NAND Interface] Initialize a data interface from
  * given ONFI mode
- * @iface: The data interface to be initialized
  * @mode: The ONFI timing mode
  */
-int onfi_init_data_interface(struct nand_chip *chip,
-			     struct nand_data_interface *iface,
+int onfi_fill_data_interface(struct nand_chip *chip,
 			     enum nand_data_interface_type type,
 			     int timing_mode)
 {
+	struct nand_data_interface *iface = &chip->data_interface;
+
 	if (type != NAND_SDR_IFACE)
 		return -EINVAL;
 
@@ -321,15 +321,4 @@ int onfi_init_data_interface(struct nand_chip *chip,
 
 	return 0;
 }
-EXPORT_SYMBOL(onfi_init_data_interface);
-
-/**
- * nand_get_default_data_interface - [NAND Interface] Retrieve NAND
- * data interface for mode 0. This is used as default timing after
- * reset.
- */
-const struct nand_data_interface *nand_get_default_data_interface(void)
-{
-	return &onfi_sdr_timings[0];
-}
-EXPORT_SYMBOL(nand_get_default_data_interface);
+EXPORT_SYMBOL(onfi_fill_data_interface);

include/linux/mtd/rawnand.h

@@ -917,7 +917,7 @@ struct nand_chip {
 	u16 max_bb_per_die;
 	u32 blocks_per_die;
 
-	struct nand_data_interface *data_interface;
+	struct nand_data_interface data_interface;
 
 	int read_retries;
 
@@ -1214,8 +1214,7 @@ static inline int onfi_get_sync_timing_mode(struct nand_chip *chip)
 	return le16_to_cpu(chip->onfi_params.src_sync_timing_mode);
 }
 
-int onfi_init_data_interface(struct nand_chip *chip,
-			     struct nand_data_interface *iface,
+int onfi_fill_data_interface(struct nand_chip *chip,
 			     enum nand_data_interface_type type,
 			     int timing_mode);
 
@@ -1258,8 +1257,6 @@ static inline int jedec_feature(struct nand_chip *chip)
 
 /* get timing characteristics from ONFI timing mode. */
 const struct nand_sdr_timings *onfi_async_timing_mode_to_sdr_timings(int mode);
-/* get data interface from ONFI timing mode 0, used after reset. */
-const struct nand_data_interface *nand_get_default_data_interface(void);
 
 int nand_check_erased_ecc_chunk(void *data, int datalen,
 				void *ecc, int ecclen,