nvmem: zynqmp: Added zynqmp nvmem firmware driver

This patch adds zynqmp nvmem firmware driver to access the
SoC revision information from the hardware register.
Signed-off-by: Nava kishore Manne <nava.manne@xilinx.com>
Acked-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>

drivers/nvmem/Kconfig

@@ -192,4 +192,14 @@ config SC27XX_EFUSE
 	  This driver can also be built as a module. If so, the module
 	  will be called nvmem-sc27xx-efuse.
 
+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 by using the firmware
+	  interface.
+
+	  If sure, say yes. If unsure, say no.
+
 endif

drivers/nvmem/Makefile

@@ -41,3 +41,5 @@ obj-$(CONFIG_RAVE_SP_EEPROM)	+= nvmem-rave-sp-eeprom.o
 nvmem-rave-sp-eeprom-y		:= rave-sp-eeprom.o
 obj-$(CONFIG_SC27XX_EFUSE)	+= nvmem-sc27xx-efuse.o
 nvmem-sc27xx-efuse-y		:= sc27xx-efuse.o
+obj-$(CONFIG_NVMEM_ZYNQMP)	+= nvmem_zynqmp_nvmem.o
+nvmem_zynqmp_nvmem-y		:= zynqmp_nvmem.o

drivers/nvmem/zynqmp_nvmem.c

+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2019 Xilinx, Inc.
+ */
+
+#include <linux/module.h>
+#include <linux/nvmem-provider.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/firmware/xlnx-zynqmp.h>
+
+#define SILICON_REVISION_MASK 0xF
+
+struct zynqmp_nvmem_data {
+	struct device *dev;
+	struct nvmem_device *nvmem;
+};
+
+static int zynqmp_nvmem_read(void *context, unsigned int offset,
+			     void *val, size_t bytes)
+{
+	int ret;
+	int idcode, version;
+	struct zynqmp_nvmem_data *priv = context;
+
+	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;
+
+	dev_dbg(priv->dev, "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 device *dev = &pdev->dev;
+	struct zynqmp_nvmem_data *priv;
+
+	priv = devm_kzalloc(dev, sizeof(struct zynqmp_nvmem_data), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->dev = dev;
+	econfig.dev = dev;
+	econfig.reg_read = zynqmp_nvmem_read;
+	econfig.priv = priv;
+
+	priv->nvmem = devm_nvmem_register(dev, &econfig);
+
+	return PTR_ERR_OR_ZERO(priv->nvmem);
+}
+
+static struct platform_driver zynqmp_nvmem_driver = {
+	.probe = zynqmp_nvmem_probe,
+	.driver = {
+		.name = "zynqmp-nvmem",
+		.of_match_table = zynqmp_nvmem_match,
+	},
+};
+
+module_platform_driver(zynqmp_nvmem_driver);
+
+MODULE_AUTHOR("Michal Simek <michal.simek@xilinx.com>, Nava kishore Manne <navam@xilinx.com>");
+MODULE_DESCRIPTION("ZynqMP NVMEM driver");
+MODULE_LICENSE("GPL");