nvmem: add new NXP QorIQ eFuse driver

Add SFP (Security Fuse Processor) read support for NXP (Freescale)
QorIQ series SOC's.

This patch adds support for the T1023 SOC using the SFP offset from
the existing T1023 device tree. In theory this should also work for
T1024, T1014 and T1013 which uses the same SFP base offset.

Signed-off-by: Richard Alpe <richard@bit42.se>
Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20230823132744.350618-13-srinivas.kandagatla@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/nvmem/Kconfig

@@ -392,4 +392,16 @@ config NVMEM_ZYNQMP
 
 	  If sure, say yes. If unsure, say no.
 
+config NVMEM_QORIQ_EFUSE
+	tristate "NXP QorIQ eFuse support"
+	depends on PPC_85xx || COMPILE_TEST
+	depends on HAS_IOMEM
+	help
+	  This driver provides read support for the eFuses (SFP) on NXP QorIQ
+	  series SoC's. This includes secure boot settings, the globally unique
+	  NXP ID 'FUIDR' and the OEM unique ID 'OUIDR'.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called nvmem_qoriq_efuse.
+
 endif

drivers/nvmem/Makefile

@@ -77,3 +77,5 @@ obj-$(CONFIG_NVMEM_VF610_OCOTP)		+= nvmem-vf610-ocotp.o
 nvmem-vf610-ocotp-y			:= vf610-ocotp.o
 obj-$(CONFIG_NVMEM_ZYNQMP)		+= nvmem_zynqmp_nvmem.o
 nvmem_zynqmp_nvmem-y			:= zynqmp_nvmem.o
+obj-$(CONFIG_NVMEM_QORIQ_EFUSE)		+= nvmem-qoriq-efuse.o
+nvmem-qoriq-efuse-y			:= qoriq-efuse.o

drivers/nvmem/qoriq-efuse.c

@@ -0,0 +1,78 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  Copyright (C) 2023  Westermo Network Technologies AB
+ */
+
+#include <linux/device.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/mod_devicetable.h>
+#include <linux/nvmem-provider.h>
+#include <linux/platform_device.h>
+
+struct qoriq_efuse_priv {
+	void __iomem *base;
+};
+
+static int qoriq_efuse_read(void *context, unsigned int offset, void *val,
+			    size_t bytes)
+{
+	struct qoriq_efuse_priv *priv = context;
+
+	/* .stride = 4 so offset is guaranteed to be aligned */
+	__ioread32_copy(val, priv->base + offset, bytes / 4);
+
+	/* Ignore trailing bytes (there shouldn't be any) */
+
+	return 0;
+}
+
+static int qoriq_efuse_probe(struct platform_device *pdev)
+{
+	struct nvmem_config config = {
+		.dev = &pdev->dev,
+		.read_only = true,
+		.reg_read = qoriq_efuse_read,
+		.stride = sizeof(u32),
+		.word_size = sizeof(u32),
+		.name = "qoriq_efuse_read",
+		.id = NVMEM_DEVID_AUTO,
+		.root_only = true,
+	};
+	struct qoriq_efuse_priv *priv;
+	struct nvmem_device *nvmem;
+	struct resource *res;
+
+	priv = devm_kzalloc(config.dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->base = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
+	if (IS_ERR(priv->base))
+		return PTR_ERR(priv->base);
+
+	config.size = resource_size(res);
+	config.priv = priv;
+	nvmem = devm_nvmem_register(config.dev, &config);
+
+	return PTR_ERR_OR_ZERO(nvmem);
+}
+
+static const struct of_device_id qoriq_efuse_of_match[] = {
+	{ .compatible = "fsl,t1023-sfp", },
+	{/* sentinel */},
+};
+MODULE_DEVICE_TABLE(of, qoriq_efuse_of_match);
+
+static struct platform_driver qoriq_efuse_driver = {
+	.probe = qoriq_efuse_probe,
+	.driver = {
+		.name = "qoriq-efuse",
+		.of_match_table = qoriq_efuse_of_match,
+	},
+};
+module_platform_driver(qoriq_efuse_driver);
+
+MODULE_AUTHOR("Richard Alpe <richard.alpe@bit42.se>");
+MODULE_DESCRIPTION("NXP QorIQ Security Fuse Processor (SFP) Reader");
+MODULE_LICENSE("GPL");