[PATCH v2 2/3] ARM: stm32mp: bbu: add NOR flash FIP update handler

[Sohaib Mohamed <sohaib.amhmd@gmail.com>]

Add a barebox update handler for STM32MP NOR flash to support firmware
updates in different scenarios. The STM32MP NOR flash layout uses offset 0
for FSBL and offset 512K for FIP, while eMMC boot partitions have FSBL at
offset 0 and FIP at offset 256K. The handler detects the image type and
flashes accordingly: standalone FIP images go to 512K, standalone FSBL
images to offset 0, and combined eMMC boot partition images (detected by
finding FIP at 256K offset) get split with FSBL flashed to offset 0 and
FIP to 512K. Images that exceed available space will fail with -ENOSPC
when pwrite_full() cannot write all bytes.

Signed-off-by: Sohaib Mohamed <sohaib.amhmd@gmail.com>
---
 arch/arm/mach-stm32mp/bbu.c | 77 +++++++++++++++++++++++++++++++++++++++++++++
 include/mach/stm32mp/bbu.h  | 10 ++++++
 2 files changed, 87 insertions(+)

diff --git a/arch/arm/mach-stm32mp/bbu.c b/arch/arm/mach-stm32mp/bbu.c
index 07b5111341..e8d0138cc7 100644
--- a/arch/arm/mach-stm32mp/bbu.c
+++ b/arch/arm/mach-stm32mp/bbu.c
@@ -193,3 +193,80 @@ int stm32mp_bbu_mmc_fip_register(const char *name,
 
 	return ret;
 }
+
+static int stm32mp_bbu_nor_fip_handler(struct bbu_handler *handler,
+			 struct bbu_data *data)
+{
+	struct bbu_data *fsbl_data, *fip_data;
+	enum filetype filetype;
+	int ret;
+
+	filetype = file_detect_type(data->image, data->len);
+	if (filetype == filetype_fip) {
+		pr_debug("Flashing FIP at offset 512K\n");
+		return bbu_flash(data, SZ_512K);
+	}
+
+	if (filetype != filetype_stm32_image_fsbl_v1) {
+		if (!bbu_force(data, "incorrect image type. Expected: %s, got %s",
+				file_type_to_string(filetype_stm32_image_fsbl_v1),
+				file_type_to_string(filetype)))
+			return -EINVAL;
+
+		/* Force: Let's assume it's an FSBL and flash anyway */
+	}
+
+	if (data->len > SZ_256K)
+		filetype = file_detect_type(data->image + SZ_256K,
+					    data->len - SZ_256K);
+	else
+		filetype = filetype_unknown;
+
+	/* Not an eMMC image, just flash 1:1 */
+	if (filetype != filetype_fip) {
+		pr_debug("Flashing FSBL at offset 0\n");
+		return bbu_flash(data, 0);
+	}
+
+	/* On SPI-NOR, offset 256K is FSBL2. If we get a FIP image there
+	 * instead, let's assume that's an eMMC boot partition image
+	 * and flash the FSBL to offset 0 and the remainder to offset 512K
+	 */
+
+	pr_debug("Flashing FSBL at offset 0\n");
+	fsbl_data = data;
+	fsbl_data->image = data->image;
+	fsbl_data->len = SZ_256K;
+
+	ret = bbu_flash(fsbl_data, 0);
+	if (ret < 0)
+		return ret;
+
+	pr_debug("Flashing FIP from file offset 256K at offset 512K\n");
+	fip_data = data;
+	fip_data->image = data->image + SZ_256K;
+	fip_data->len = data->len - SZ_256K;
+
+	return bbu_flash(fip_data, SZ_512K);
+}
+
+int stm32mp_bbu_nor_fip_register(const char *name,
+				 const char *devicefile,
+				 unsigned long flags)
+{
+	struct stm32mp_bbu_handler *priv;
+	int ret;
+
+	priv = xzalloc(sizeof(*priv));
+
+	priv->handler.flags = flags;
+	priv->handler.devicefile = devicefile;
+	priv->handler.name = name;
+	priv->handler.handler = stm32mp_bbu_nor_fip_handler;
+
+	ret = bbu_register_handler(&priv->handler);
+	if (ret)
+		free(priv);
+
+	return ret;
+}
diff --git a/include/mach/stm32mp/bbu.h b/include/mach/stm32mp/bbu.h
index 233bcf6478..87b29f1527 100644
--- a/include/mach/stm32mp/bbu.h
+++ b/include/mach/stm32mp/bbu.h
@@ -10,6 +10,9 @@
 int stm32mp_bbu_mmc_fip_register(const char *name, const char *devicefile,
 				 unsigned long flags);
 
+int stm32mp_bbu_nor_fip_register(const char *name, const char *devicefile,
+				 unsigned long flags);
+
 #else
 
 static inline int stm32mp_bbu_mmc_fip_register(const char *name,
@@ -19,6 +22,13 @@ static inline int stm32mp_bbu_mmc_fip_register(const char *name,
 	return -ENOSYS;
 }
 
+static inline int stm32mp_bbu_nor_fip_register(const char *name,
+					       const char *devicefile,
+					       unsigned long flags)
+{
+	return -ENOSYS;
+}
+
 #endif
 
 #endif /* MACH_STM32MP_BBU_H_ */

-- 
2.43.0