[PATCH v1] nvmem: bsec.c: add optional permanent write support

[Oleksij Rempel]

To be able to fuze MAC address we need to be able to use BSEC_SMC_PROG_OTP
instead of BSEC_SMC_WRITE_SHADOW.

Signed-off-by: Oleksij Rempel <o.rempel at pengutronix.de>
---
 drivers/nvmem/Kconfig | 11 +++++++++++
 drivers/nvmem/bsec.c  | 22 +++++++++++++++++++---
 2 files changed, 30 insertions(+), 3 deletions(-)

diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig
index d809fb6eab..1bb477a997 100644
--- a/drivers/nvmem/Kconfig
+++ b/drivers/nvmem/Kconfig
@@ -66,6 +66,17 @@ config STM32_BSEC
 	  This adds support for the STM32 OTP controller. Reads and writes
 	  to will go to the shadow RAM, not the OTP fuses themselvers.
 
+config STM32_BSEC_WRITE
+	bool
+	prompt "Enable write support of STM32 CPUs OTP fuses"
+	depends on STM32_BSEC
+	help
+	  This adds write support to STM32 On-Chip OTP registers. Example of set
+	  MAC to 12:34:56:78:9A:BC:
+	    bsec0.permanent_write_enable=1
+	    mw -l -d /dev/stm32-bsec 0x000000e4+4 0x78563412
+	    mw -l -d /dev/stm32-bsec 0x000000e8+4 0x0000bc9a
+
 config STARFIVE_OTP
 	tristate "Starfive OTP Supprot"
 	depends on SOC_STARFIVE
diff --git a/drivers/nvmem/bsec.c b/drivers/nvmem/bsec.c
index 2d35d12df3..86b943a45d 100644
--- a/drivers/nvmem/bsec.c
+++ b/drivers/nvmem/bsec.c
@@ -21,8 +21,10 @@
 #define BSEC_OTP_SERIAL	13
 
 struct bsec_priv {
+	struct device_d dev;
 	u32 svc_id;
 	struct regmap_config map_config;
+	int permanent_write_enable;
 };
 
 struct stm32_bsec_data {
@@ -59,13 +61,18 @@ static int stm32_bsec_read_shadow(void *ctx, unsigned reg, unsigned *val)
 	return bsec_smc(ctx, BSEC_SMC_READ_SHADOW, reg, 0, val);
 }
 
-static int stm32_bsec_reg_write_shadow(void *ctx, unsigned reg, unsigned val)
+static int stm32_bsec_reg_write(void *ctx, unsigned reg, unsigned val)
 {
-	return bsec_smc(ctx, BSEC_SMC_WRITE_SHADOW, reg, val, NULL);
+	struct bsec_priv *priv = ctx;
+
+	if (priv->permanent_write_enable)
+		return bsec_smc(ctx, BSEC_SMC_PROG_OTP, reg, val, NULL);
+	else
+		return bsec_smc(ctx, BSEC_SMC_WRITE_SHADOW, reg, val, NULL);
 }
 
 static struct regmap_bus stm32_bsec_regmap_bus = {
-	.reg_write = stm32_bsec_reg_write_shadow,
+	.reg_write = stm32_bsec_reg_write,
 	.reg_read = stm32_bsec_read_shadow,
 };
 
@@ -150,6 +157,10 @@ static int stm32_bsec_probe(struct device_d *dev)
 
 	priv->svc_id = data->svc_id;
 
+	dev_set_name(&priv->dev, "bsec");
+	priv->dev.parent = dev;
+	register_device(&priv->dev);
+
 	priv->map_config.reg_bits = 32;
 	priv->map_config.val_bits = 32;
 	priv->map_config.reg_stride = 4;
@@ -159,6 +170,11 @@ static int stm32_bsec_probe(struct device_d *dev)
 	if (IS_ERR(map))
 		return PTR_ERR(map);
 
+	if (IS_ENABLED(CONFIG_STM32_BSEC_WRITE)) {
+		dev_add_param_bool(&priv->dev, "permanent_write_enable",
+				NULL, NULL, &priv->permanent_write_enable, NULL);
+	}
+
 	nvmem = nvmem_regmap_register(map, "stm32-bsec");
 	if (IS_ERR(nvmem))
 		return PTR_ERR(nvmem);
-- 
2.30.2