[RFC 2/2] nvmem: zynqmp: Added zynqmp nvmem firmware driver

[chinnikishore369 at gmail.com]

From: Nava kishore Manne <navam at xilinx.com>

This patch adds zynqmp nvmem firmware driver to access the
SoC revision information from the hardware register.

Signed-off-by: Nava kishore Manne <navam at xilinx.com>
---
 drivers/nvmem/Kconfig        |  9 +++++
 drivers/nvmem/Makefile       |  2 ++
 drivers/nvmem/zynqmp_nvmem.c | 85 ++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 96 insertions(+)
 create mode 100644 drivers/nvmem/zynqmp_nvmem.c

diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig
index ff505af064ba..a9349281d05a 100644
--- a/drivers/nvmem/Kconfig
+++ b/drivers/nvmem/Kconfig
@@ -175,4 +175,13 @@ config NVMEM_SNVS_LPGPR
 	  This driver can also be built as a module. If so, the module
 	  will be called nvmem-snvs-lpgpr.
 
+config NVMEM_ZYNQMP
+        bool "Xilinx ZYNQMP SoC nvmem firmware support"
+        depends on ARCH_ZYNQMP
+        help
+          This is a driver to access hardware related data like soc revision,
+          IDCODE... etc.
+
+          If sure, say yes. If unsure, say no.
+
 endif
diff --git a/drivers/nvmem/Makefile b/drivers/nvmem/Makefile
index e54dcfa6565a..932b4cebcb6c 100644
--- a/drivers/nvmem/Makefile
+++ b/drivers/nvmem/Makefile
@@ -37,3 +37,5 @@ obj-$(CONFIG_MESON_MX_EFUSE)	+= nvmem_meson_mx_efuse.o
 nvmem_meson_mx_efuse-y		:= meson-mx-efuse.o
 obj-$(CONFIG_NVMEM_SNVS_LPGPR)	+= nvmem_snvs_lpgpr.o
 nvmem_snvs_lpgpr-y		:= snvs_lpgpr.o
+obj-$(CONFIG_NVMEM_ZYNQMP)	+= nvmem_zynqmp_nvmem.o
+nvmem_zynqmp_nvmem-y		:= zynqmp_nvmem.o
diff --git a/drivers/nvmem/zynqmp_nvmem.c b/drivers/nvmem/zynqmp_nvmem.c
new file mode 100644
index 000000000000..206ec9bd775d
--- /dev/null
+++ b/drivers/nvmem/zynqmp_nvmem.c
@@ -0,0 +1,85 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2018 Xilinx, Inc.
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/nvmem-provider.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/firmware/xilinx/zynqmp/firmware.h>
+
+#define SILICON_REVISION_MASK 0xF
+
+static int zynqmp_nvmem_read(void *context, unsigned int offset,
+					void *val, size_t bytes)
+{
+	int ret;
+	int idcode, version;
+	const struct zynqmp_eemi_ops *eemi_ops = zynqmp_pm_get_eemi_ops();
+
+	if (!eemi_ops || !eemi_ops->get_chipid)
+		return -ENXIO;
+
+	ret = eemi_ops->get_chipid(&idcode, &version);
+	if (ret < 0)
+		return ret;
+
+	pr_debug("Read chipid val %x %x\n", idcode, version);
+	*(int *)val = version & SILICON_REVISION_MASK;
+
+	return 0;
+}
+
+static struct nvmem_config econfig = {
+	.name = "zynqmp-nvmem",
+	.owner = THIS_MODULE,
+	.word_size = 1,
+	.size = 1,
+	.read_only = true,
+};
+
+static const struct of_device_id zynqmp_nvmem_match[] = {
+	{ .compatible = "xlnx,zynqmp-nvmem-fw", },
+	{ /* sentinel */ },
+};
+MODULE_DEVICE_TABLE(of, zynqmp_nvmem_match);
+
+static int zynqmp_nvmem_probe(struct platform_device *pdev)
+{
+	struct nvmem_device *nvmem;
+
+	econfig.dev = &pdev->dev;
+	econfig.reg_read = zynqmp_nvmem_read;
+
+	nvmem = nvmem_register(&econfig);
+	if (IS_ERR(nvmem))
+		return PTR_ERR(nvmem);
+
+	platform_set_drvdata(pdev, nvmem);
+
+	return 0;
+}
+
+static int zynqmp_nvmem_remove(struct platform_device *pdev)
+{
+	struct nvmem_device *nvmem = platform_get_drvdata(pdev);
+
+	return nvmem_unregister(nvmem);
+}
+
+static struct platform_driver zynqmp_nvmem_driver = {
+	.probe = zynqmp_nvmem_probe,
+	.remove = zynqmp_nvmem_remove,
+	.driver = {
+		.name = "zynqmp-nvmem",
+		.of_match_table = zynqmp_nvmem_match,
+	},
+};
+
+module_platform_driver(zynqmp_nvmem_driver);
+
+MODULE_AUTHOR("Michal Simek <michal.simek at xilinx.com>, Nava kishore Manne <navam at xilinx.com>");
+MODULE_DESCRIPTION("ZynqMP NVMEM driver");
+MODULE_LICENSE("GPL");
-- 
2.16.1