mtd: rawnand: Allocate the interface configurations dynamically

Instead of manipulating the statically allocated structure and copy
timings around, allocate one at identification time and save it in the
nand_chip structure once it has been initialized.

All NAND chips using the same interface configuration during reset and
startup, we define a helper to retrieve a single reset interface
configuration object, shared across all NAND chips.

We use a second pointer to always have a reference on the currently
applied interface configuration, which may either point to the "best
interface configuration" or to the "default reset interface
configuration".

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Link: https://lore.kernel.org/linux-mtd/20200529111322.7184-29-miquel.raynal@bootlin.com

drivers/mtd/nand/raw/internals.h

@@ -93,6 +93,7 @@ onfi_find_closest_sdr_mode(const struct nand_sdr_timings *spec_timings);
 int nand_choose_best_sdr_timings(struct nand_chip *chip,
 				 struct nand_interface_config *iface,
 				 struct nand_sdr_timings *spec_timings);
+const struct nand_interface_config *nand_get_reset_interface_config(void);
 int nand_get_features(struct nand_chip *chip, int addr, u8 *subfeature_param);
 int nand_set_features(struct nand_chip *chip, int addr, u8 *subfeature_param);
 int nand_read_page_raw_notsupp(struct nand_chip *chip, u8 *buf,

drivers/mtd/nand/raw/nand_base.c

@@ -928,9 +928,9 @@ static int nand_reset_interface(struct nand_chip *chip, int chipnr)
 	 * timings to timing mode 0.
 	 */
 
-	onfi_fill_interface_config(chip, &chip->interface_config,
-				   NAND_SDR_IFACE, 0);
-	ret = ops->setup_interface(chip, chipnr, &chip->interface_config);
+	chip->current_interface_config = nand_get_reset_interface_config();
+	ret = ops->setup_interface(chip, chipnr,
+				   chip->current_interface_config);
 	if (ret)
 		pr_err("Failed to configure data interface to SDR timing mode 0\n");
 
@@ -949,13 +949,25 @@ static int nand_reset_interface(struct nand_chip *chip, int chipnr)
  */
 static int nand_setup_interface(struct nand_chip *chip, int chipnr)
 {
-	u8 mode = chip->interface_config.timings.mode;
-	u8 tmode_param[ONFI_SUBFEATURE_PARAM_LEN] = { mode, };
+	const struct nand_controller_ops *ops = chip->controller->ops;
+	u8 tmode_param[ONFI_SUBFEATURE_PARAM_LEN] = { };
 	int ret;
 
 	if (!nand_controller_can_setup_interface(chip))
 		return 0;
 
+	/*
+	 * A nand_reset_interface() put both the NAND chip and the NAND
+	 * controller in timings mode 0. If the default mode for this chip is
+	 * also 0, no need to proceed to the change again. Plus, at probe time,
+	 * nand_setup_interface() uses ->set/get_features() which would
+	 * fail anyway as the parameter page is not available yet.
+	 */
+	if (!chip->best_interface_config)
+		return 0;
+
+	tmode_param[0] = chip->best_interface_config->timings.mode;
+
 	/* Change the mode on the chip side (if supported by the NAND chip) */
 	if (nand_supports_set_features(chip, ONFI_FEATURE_ADDR_TIMING_MODE)) {
 		nand_select_target(chip, chipnr);
@@ -967,14 +979,13 @@ static int nand_setup_interface(struct nand_chip *chip, int chipnr)
 	}
 
 	/* Change the mode on the controller side */
-	ret = chip->controller->ops->setup_interface(chip, chipnr,
-						     &chip->interface_config);
+	ret = ops->setup_interface(chip, chipnr, chip->best_interface_config);
 	if (ret)
 		return ret;
 
 	/* Check the mode has been accepted by the chip, if supported */
 	if (!nand_supports_get_features(chip, ONFI_FEATURE_ADDR_TIMING_MODE))
-		return 0;
+		goto update_interface_config;
 
 	memset(tmode_param, 0, ONFI_SUBFEATURE_PARAM_LEN);
 	nand_select_target(chip, chipnr);
@@ -984,12 +995,15 @@ static int nand_setup_interface(struct nand_chip *chip, int chipnr)
 	if (ret)
 		goto err_reset_chip;
 
-	if (tmode_param[0] != mode) {
+	if (tmode_param[0] != chip->best_interface_config->timings.mode) {
 		pr_warn("timing mode %d not acknowledged by the NAND chip\n",
-			mode);
+			chip->best_interface_config->timings.mode);
 		goto err_reset_chip;
 	}
 
+update_interface_config:
+	chip->current_interface_config = chip->best_interface_config;
+
 	return 0;
 
 err_reset_chip:
@@ -1031,8 +1045,10 @@ int nand_choose_best_sdr_timings(struct nand_chip *chip,
 		/* Verify the controller supports the requested interface */
 		ret = ops->setup_interface(chip, NAND_DATA_IFACE_CHECK_ONLY,
 					   iface);
-		if (!ret)
+		if (!ret) {
+			chip->best_interface_config = iface;
 			return ret;
+		}
 
 		/* Fallback to slower modes */
 		best_mode = iface->timings.mode;
@@ -1046,9 +1062,11 @@ int nand_choose_best_sdr_timings(struct nand_chip *chip,
 		ret = ops->setup_interface(chip, NAND_DATA_IFACE_CHECK_ONLY,
 					   iface);
 		if (!ret)
-			return 0;
+			break;
 	}
 
+	chip->best_interface_config = iface;
+
 	return 0;
 }
 
@@ -1067,15 +1085,25 @@ int nand_choose_best_sdr_timings(struct nand_chip *chip,
  */
 static int nand_choose_interface_config(struct nand_chip *chip)
 {
+	struct nand_interface_config *iface;
+	int ret;
+
 	if (!nand_controller_can_setup_interface(chip))
 		return 0;
 
-	if (chip->ops.choose_interface_config)
-		return chip->ops.choose_interface_config(chip,
-							 &chip->interface_config);
+	iface = kzalloc(sizeof(*iface), GFP_KERNEL);
+	if (!iface)
+		return -ENOMEM;
 
-	return nand_choose_best_sdr_timings(chip, &chip->interface_config,
-					    NULL);
+	if (chip->ops.choose_interface_config)
+		ret = chip->ops.choose_interface_config(chip, iface);
+	else
+		ret = nand_choose_best_sdr_timings(chip, iface, NULL);
+
+	if (ret)
+		kfree(iface);
+
+	return ret;
 }
 
 /**
@@ -2501,7 +2529,6 @@ EXPORT_SYMBOL_GPL(nand_subop_get_data_len);
  */
 int nand_reset(struct nand_chip *chip, int chipnr)
 {
-	struct nand_interface_config saved_intf_config = chip->interface_config;
 	int ret;
 
 	ret = nand_reset_interface(chip, chipnr);
@@ -2519,18 +2546,6 @@ int nand_reset(struct nand_chip *chip, int chipnr)
 	if (ret)
 		return ret;
 
-	/*
-	 * A nand_reset_interface() put both the NAND chip and the NAND
-	 * controller in timings mode 0. If the default mode for this chip is
-	 * also 0, no need to proceed to the change again. Plus, at probe time,
-	 * nand_setup_interface() uses ->set/get_features() which would
-	 * fail anyway as the parameter page is not available yet.
-	 */
-	if (!memcmp(&chip->interface_config, &saved_intf_config,
-		    sizeof(saved_intf_config)))
-		return 0;
-
-	chip->interface_config = saved_intf_config;
 	ret = nand_setup_interface(chip, chipnr);
 	if (ret)
 		return ret;
@@ -5198,7 +5213,7 @@ static int nand_scan_ident(struct nand_chip *chip, unsigned int maxchips,
 	mutex_init(&chip->lock);
 
 	/* Enforce the right timings for reset/detection */
-	onfi_fill_interface_config(chip, &chip->interface_config, NAND_SDR_IFACE, 0);
+	chip->current_interface_config = nand_get_reset_interface_config();
 
 	ret = nand_dt_init(chip);
 	if (ret)
@@ -5994,7 +6009,7 @@ static int nand_scan_tail(struct nand_chip *chip)
 	for (i = 0; i < nanddev_ntargets(&chip->base); i++) {
 		ret = nand_setup_interface(chip, i);
 		if (ret)
-			goto err_nanddev_cleanup;
+			goto err_free_interface_config;
 	}
 
 	/* Check, if we should skip the bad block table scan */
@@ -6004,10 +6019,12 @@ static int nand_scan_tail(struct nand_chip *chip)
 	/* Build bad block table */
 	ret = nand_create_bbt(chip);
 	if (ret)
-		goto err_nanddev_cleanup;
+		goto err_free_interface_config;
 
 	return 0;
 
+err_free_interface_config:
+	kfree(chip->best_interface_config);
 
 err_nanddev_cleanup:
 	nanddev_cleanup(&chip->base);
@@ -6101,6 +6118,9 @@ void nand_cleanup(struct nand_chip *chip)
 			& NAND_BBT_DYNAMICSTRUCT)
 		kfree(chip->badblock_pattern);
 
+	/* Free the data interface */
+	kfree(chip->best_interface_config);
+
 	/* Free manufacturer priv data. */
 	nand_manufacturer_cleanup(chip);
 

drivers/mtd/nand/raw/nand_timings.c

@@ -292,6 +292,12 @@ static const struct nand_interface_config onfi_sdr_timings[] = {
 	},
 };
 
+/* All NAND chips share the same reset data interface: SDR mode 0 */
+const struct nand_interface_config *nand_get_reset_interface_config(void)
+{
+	return &onfi_sdr_timings[0];
+}
+
 /**
  * onfi_find_closest_sdr_mode - Derive the closest ONFI SDR timing mode given a
  *                              set of timings

include/linux/mtd/rawnand.h

@@ -1069,7 +1069,11 @@ struct nand_manufacturer {
  * @options: Various chip options. They can partly be set to inform nand_scan
  *           about special functionality. See the defines for further
  *           explanation.
- * @interface_config: NAND interface timing information
+ * @current_interface_config: The currently used NAND interface configuration
+ * @best_interface_config: The best NAND interface configuration which fits both
+ *                         the NAND chip and NAND controller constraints. If
+ *                         unset, the default reset interface configuration must
+ *                         be used.
  * @bbt_erase_shift: Number of address bits in a bbt entry
  * @bbt_options: Bad block table specific options. All options used here must
  *               come from bbm.h. By default, these options will be copied to
@@ -1116,7 +1120,8 @@ struct nand_chip {
 	unsigned int options;
 
 	/* Data interface */
-	struct nand_interface_config interface_config;
+	const struct nand_interface_config *current_interface_config;
+	struct nand_interface_config *best_interface_config;
 
 	/* Bad block information */
 	unsigned int bbt_erase_shift;
@@ -1209,7 +1214,7 @@ static inline struct device_node *nand_get_flash_node(struct nand_chip *chip)
 static inline const struct nand_interface_config *
 nand_get_interface_config(struct nand_chip *chip)
 {
-	return &chip->interface_config;
+	return chip->current_interface_config;
 }
 
 /*