[PATCH 3/3] mtd: rawnand: denali: Do not reset the block on SoCFPGA

[Marek Vasut]

Legacy kernel versions for SoCFPGA may not implement proper reset
handling. Apply the same approach as SoCFPGA reset driver, check
environment variable "socfpga_legacy_reset_compat", and if it is
set, do not reset the IP before booting Linux. This way, even the
older kernel versions can be booted by up to date U-Boot.

Signed-off-by: Marek Vasut <marex at denx.de>
Cc: Masahiro Yamada <yamada.masahiro at socionext.com>
---
 drivers/mtd/nand/raw/denali_dt.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/mtd/nand/raw/denali_dt.c b/drivers/mtd/nand/raw/denali_dt.c
index 2c9e249ab6..d35f2a3543 100644
--- a/drivers/mtd/nand/raw/denali_dt.c
+++ b/drivers/mtd/nand/raw/denali_dt.c
@@ -148,6 +148,18 @@ static int denali_dt_remove(struct udevice *dev)
 {
 	struct denali_nand_info *denali = dev_get_priv(dev);
 
+#if CONFIG_IS_ENABLED(ARCH_SOCFPGA)
+	/*
+	 * Legacy kernel versions do not implement proper reset handling on
+	 * SoCFPGA. To let those older kernel versions work, reuse the same
+	 * approach as the SoCFPGA reset driver does -- check environment
+	 * variable socfpga_legacy_reset_compat and avoid resetting the IP
+	 * before booting the kernel if it is set to 1.
+	 */
+	if (env_get_ulong("socfpga_legacy_reset_compat", 10, 0))
+		return 0;
+#endif
+
 	return reset_release_bulk(&denali->resets);
 }
 
-- 
2.24.1