[PATCH v2] mtd: rawnand: gpmi: add debugfs entry for BCH geometry

[han.xu@oss.nxp.com]

From: Han Xu <han.xu@nxp.com>

Export the BCH geometry parameters via debugfs to aid debugging and
provide the necessary information for legacy kobs-ng tool. The debugfs
directory "gpmi-nand" is created under the root debugfs tree, exposing:

bch_geometry  - blob containing the struct bch_geometry fields
raw_mode      - flag indicating raw mode status

The implementation is guarded with #ifdef CONFIG_DEBUG_FS to avoid
build failures when debugfs is disabled.

Signed-off-by: Han Xu <han.xu@nxp.com>
---
Changes in v2:
- Move dbg_root and dbg_bch_geo into struct gpmi_nand_data to fix
  use-after-free on device unbind.
- Replace debugfs_create_file_full() with debugfs_create_bool() to
  expose the raw_mode flag.
- Register a devm cleanup action to call debugfs_remove_recursive() on
  driver removal.

To: Han Xu <han.xu@nxp.com>
To: Miquel Raynal <miquel.raynal@bootlin.com>
To: Richard Weinberger <richard@nod.at>
To: Vignesh Raghavendra <vigneshr@ti.com>
Cc: imx@lists.linux.dev
Cc: linux-mtd@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
---
 drivers/mtd/nand/raw/gpmi-nand/gpmi-nand.c | 29 +++++++++++++++++++++++++++++
 drivers/mtd/nand/raw/gpmi-nand/gpmi-nand.h |  6 ++++++
 2 files changed, 35 insertions(+)

diff --git a/drivers/mtd/nand/raw/gpmi-nand/gpmi-nand.c b/drivers/mtd/nand/raw/gpmi-nand/gpmi-nand.c
index c1f766cb225aa..527165ccc839d 100644
--- a/drivers/mtd/nand/raw/gpmi-nand/gpmi-nand.c
+++ b/drivers/mtd/nand/raw/gpmi-nand/gpmi-nand.c
@@ -7,6 +7,7 @@
  */
 #include <linux/cleanup.h>
 #include <linux/clk.h>
+#include <linux/debugfs.h>
 #include <linux/delay.h>
 #include <linux/slab.h>
 #include <linux/sched/task_stack.h>
@@ -732,6 +733,31 @@ static int common_nfc_set_geometry(struct gpmi_nand_data *this)
 	return err;
 }
 
+#ifdef CONFIG_DEBUG_FS
+static void bch_remove_debugfs(void *data)
+{
+	struct gpmi_nand_data *this = data;
+
+	debugfs_remove_recursive(this->dbg_root);
+	this->dbg_root = NULL;
+}
+
+static void bch_create_debugfs(struct gpmi_nand_data *this)
+{
+	struct bch_geometry *bch_geo = &this->bch_geometry;
+
+	this->dbg_root = debugfs_create_dir("gpmi-nand", NULL);
+	this->dbg_bch_geo.data = (void *)bch_geo;
+	this->dbg_bch_geo.size = sizeof(struct bch_geometry);
+	this->raw_mode = true;
+	debugfs_create_blob("bch_geometry", 0444, this->dbg_root, &this->dbg_bch_geo);
+	debugfs_create_bool("raw_mode", 0444, this->dbg_root, &this->raw_mode);
+	devm_add_action_or_reset(this->dev, bch_remove_debugfs, this);
+}
+#else
+static void bch_create_debugfs(struct gpmi_nand_data *this) {}
+#endif /* CONFIG_DEBUG_FS */
+
 /* Configures the geometry for BCH.  */
 static int bch_set_geometry(struct gpmi_nand_data *this)
 {
@@ -2282,6 +2308,9 @@ static int gpmi_init_last(struct gpmi_nand_data *this)
 	if (ret)
 		return ret;
 
+	/* save BCH geometry to debugfs if CONFIG_DEBUG_FS is enabled */
+	bch_create_debugfs(this);
+
 	/* Init the nand_ecc_ctrl{} */
 	ecc->read_page	= gpmi_ecc_read_page;
 	ecc->write_page	= gpmi_ecc_write_page;
diff --git a/drivers/mtd/nand/raw/gpmi-nand/gpmi-nand.h b/drivers/mtd/nand/raw/gpmi-nand/gpmi-nand.h
index 3e9bc985e44a3..80c32efbaef86 100644
--- a/drivers/mtd/nand/raw/gpmi-nand/gpmi-nand.h
+++ b/drivers/mtd/nand/raw/gpmi-nand/gpmi-nand.h
@@ -161,6 +161,12 @@ struct gpmi_nand_data {
 #define DMA_CHANS		8
 	struct dma_chan		*dma_chans[DMA_CHANS];
 	struct completion	dma_done;
+
+#ifdef CONFIG_DEBUG_FS
+	struct			dentry *dbg_root;
+	struct			debugfs_blob_wrapper dbg_bch_geo;
+	bool			raw_mode;
+#endif
 };
 
 /* BCH : Status Block Completion Codes */

---
base-commit: f97bdc8ec1dc7b33781a702eeba55326c206be56
change-id: 20260727-nand_debugfs-74d6d6ba52df

Best regards,
--  
Han Xu <han.xu@nxp.com>