[PATCH v5 10/17] nvmem: microchip-otpc: nvmem: add emulation mode and OTP access validation

Add validation of OTP memory accessibility and emulation mode status
during probe.

When the boot packet is not configured, emulation mode allows access to
the other packets. When both are not available an informational message
is logged to help with debugging.

Signed-off-by: Varshini Rajendran <[email protected]>
---
 drivers/nvmem/microchip-otpc.c | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/drivers/nvmem/microchip-otpc.c b/drivers/nvmem/microchip-otpc.c
index a17f82afdc37..6b0184423463 100644
--- a/drivers/nvmem/microchip-otpc.c
+++ b/drivers/nvmem/microchip-otpc.c
@@ -18,6 +18,7 @@
 #define MCHP_OTPC_CR_READ		BIT(6)
 #define MCHP_OTPC_MR			(0x4)
 #define MCHP_OTPC_MR_ADDR		GENMASK(31, 16)
+#define MCHP_OTPC_MR_EMUL		BIT(7)
 #define MCHP_OTPC_AR			(0x8)
 #define MCHP_OTPC_SR			(0xc)
 #define MCHP_OTPC_SR_READ		BIT(6)
@@ -343,7 +344,8 @@ static int mchp_otpc_probe(struct platform_device *pdev)
 {
 	struct nvmem_device *nvmem;
 	struct mchp_otpc *otpc;
-	u32 size;
+	bool emul_enable;
+	u32 size, mr_val;
 	int ret;
 
 	otpc = devm_kzalloc(&pdev->dev, sizeof(*otpc), GFP_KERNEL);
@@ -355,10 +357,22 @@ static int mchp_otpc_probe(struct platform_device *pdev)
 		return PTR_ERR(otpc->base);
 
 	otpc->dev = &pdev->dev;
+
+	mr_val = readl_relaxed(otpc->base + MCHP_OTPC_MR);
+	emul_enable = mr_val & MCHP_OTPC_MR_EMUL;
+	if (emul_enable)
+		dev_info(otpc->dev, "Emulation mode enabled\n");
+
 	ret = mchp_otpc_init_packets_list(otpc, &size);
 	if (ret)
 		return ret;
 
+	if (!size) {
+		dev_warn(otpc->dev, "Cannot access OTP memory\n");
+		if (!emul_enable)
+			dev_info(otpc->dev, "Boot packet not programmed and emulation mode disabled\n");
+	}
+
 	mchp_nvmem_config.dev = otpc->dev;
 	mchp_nvmem_config.add_legacy_fixed_of_cells = true;
 	mchp_nvmem_config.size = size;
-- 
2.34.1