[PATCH v2 3/6] soc: actions: Add Actions Semi Owl socinfo driver

[Cristian Ciocaltea <cristian.ciocaltea@gmail.com>]

The driver provides information about the Action Semi Owl family of
SoCs (S500, S700 and S900) to user space via sysfs: machine, family,
soc_id, serial_number.

Note the serial number is currently provided only for the S500 SoC
variant.

Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@gmail.com>
---
 drivers/soc/actions/Kconfig                   |   8 +
 drivers/soc/actions/Makefile                  |   1 +
 drivers/soc/actions/owl-socinfo.c             | 152 ++++++++++++++++++
 include/linux/soc/actions/owl-serial-number.h |  20 +++
 4 files changed, 181 insertions(+)
 create mode 100644 drivers/soc/actions/owl-socinfo.c
 create mode 100644 include/linux/soc/actions/owl-serial-number.h

diff --git a/drivers/soc/actions/Kconfig b/drivers/soc/actions/Kconfig
index 1aca2058a40c..15faade9282d 100644
--- a/drivers/soc/actions/Kconfig
+++ b/drivers/soc/actions/Kconfig
@@ -14,4 +14,12 @@ config OWL_PM_DOMAINS
 	  power-gating on Actions Semiconductor S500, S700 and S900 SoCs.
 	  If unsure, say 'n'.
 
+config OWL_SOCINFO
+	bool "Actions Semi Owl SoC info driver"
+	default ARCH_ACTIONS
+	select SOC_BUS
+	help
+	  Say 'y' here to support the Action Semiconductor Owl socinfo
+	  driver, providing information about the SoC to user space.
+
 endif
diff --git a/drivers/soc/actions/Makefile b/drivers/soc/actions/Makefile
index 4db9e7b050e5..4b2591d3089f 100644
--- a/drivers/soc/actions/Makefile
+++ b/drivers/soc/actions/Makefile
@@ -2,3 +2,4 @@
 
 obj-$(CONFIG_OWL_PM_DOMAINS_HELPER) += owl-sps-helper.o
 obj-$(CONFIG_OWL_PM_DOMAINS) += owl-sps.o
+obj-$(CONFIG_OWL_SOCINFO) += owl-socinfo.o
diff --git a/drivers/soc/actions/owl-socinfo.c b/drivers/soc/actions/owl-socinfo.c
new file mode 100644
index 000000000000..f28eafac3792
--- /dev/null
+++ b/drivers/soc/actions/owl-socinfo.c
@@ -0,0 +1,152 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Actions Semi Owl SoC information driver
+ *
+ * Copyright (c) 2021 Cristian Ciocaltea <cristian.ciocaltea@gmail.com>
+ */
+
+#include <linux/of_address.h>
+#include <linux/of_platform.h>
+#include <linux/of_reserved_mem.h>
+#include <linux/platform_device.h>
+#include <linux/random.h>
+#include <linux/soc/actions/owl-serial-number.h>
+#include <linux/sys_soc.h>
+
+struct owl_soc_serial_rmem {
+	u32 low;
+	u32 high;
+};
+
+static struct owl_soc_serial_rmem *owl_socinfo_serial;
+
+u32 owl_get_soc_serial_low(void)
+{
+	return owl_socinfo_serial ? owl_socinfo_serial->low : 0;
+}
+EXPORT_SYMBOL_GPL(owl_get_soc_serial_low);
+
+u32 owl_get_soc_serial_high(void)
+{
+	return owl_socinfo_serial ? owl_socinfo_serial->high : 0;
+}
+EXPORT_SYMBOL_GPL(owl_get_soc_serial_high);
+
+struct owl_soc_info {
+	char *name;
+	int (*read_soc_serial)(struct device *dev);
+};
+
+/*
+ * Access SoC's serial number stored by the bootloader in DDR memory.
+ */
+static int owl_socinfo_read_serial_rmem(struct device *dev)
+{
+	struct reserved_mem *rmem;
+	struct device_node *np;
+	int ret = 0;
+
+	np = of_find_compatible_node(NULL, NULL, "actions,owl-soc-serial");
+	if (!np)
+		return -ENXIO;
+
+	rmem = of_reserved_mem_lookup(np);
+	if (!rmem) {
+		dev_err(dev, "failed to acquire reserved memory region\n");
+		ret = -EINVAL;
+		goto out_put;
+	}
+
+	owl_socinfo_serial = memremap(rmem->base, rmem->size, MEMREMAP_WB);
+	if (!owl_socinfo_serial)
+		ret = -ENOMEM;
+
+out_put:
+	of_node_put(np);
+	return ret;
+}
+
+static int owl_socinfo_probe(struct platform_device *pdev)
+{
+	const struct owl_soc_info *soc_info;
+	struct soc_device_attribute *soc_dev_attr;
+	struct soc_device *soc_dev;
+	const char *sn;
+	int ret;
+
+	soc_info = of_device_get_match_data(&pdev->dev);
+	if (!soc_info)
+		return -ENODEV;
+
+	soc_dev_attr = devm_kzalloc(&pdev->dev, sizeof(*soc_dev_attr),
+				    GFP_KERNEL);
+	if (!soc_dev_attr)
+		return -ENOMEM;
+
+	ret = of_property_read_string(of_root, "model", &soc_dev_attr->machine);
+	if (ret)
+		return ret;
+
+	soc_dev_attr->family = "Actions Semi Owl";
+	soc_dev_attr->soc_id = soc_info->name;
+
+	if (soc_info->read_soc_serial) {
+		ret = soc_info->read_soc_serial(&pdev->dev);
+
+		if (!ret) {
+			sn = devm_kasprintf(&pdev->dev, GFP_KERNEL, "%08x%08x",
+					    owl_get_soc_serial_high(),
+					    owl_get_soc_serial_low());
+			soc_dev_attr->serial_number = sn;
+			/* Feed the SoC unique data into entropy pool. */
+			add_device_randomness(sn, 16);
+		}
+	}
+
+	soc_dev = soc_device_register(soc_dev_attr);
+	if (IS_ERR(soc_dev))
+		return dev_err_probe(&pdev->dev, PTR_ERR(soc_dev),
+				     "failed to register soc device");
+
+	dev_info(soc_device_to_device(soc_dev),
+		 "SoC: %s %s\n",
+		 soc_dev_attr->family, soc_dev_attr->soc_id);
+
+	return 0;
+}
+
+static const struct owl_soc_info s500_soc_info = {
+	.name = "S500",
+	.read_soc_serial = owl_socinfo_read_serial_rmem,
+};
+
+static const struct owl_soc_info s700_soc_info = {
+	.name = "S700",
+	/* FIXME: provide read_soc_serial */
+};
+
+static const struct owl_soc_info s900_soc_info = {
+	.name = "S900",
+	/* FIXME: provide read_soc_serial */
+};
+
+static const struct of_device_id owl_socinfo_of_match[] = {
+	{ .compatible = "actions,s500-soc", .data = &s500_soc_info, },
+	{ .compatible = "actions,s700-soc", .data = &s700_soc_info, },
+	{ .compatible = "actions,s900-soc", .data = &s900_soc_info, },
+	{ }
+};
+
+static struct platform_driver owl_socinfo_platform_driver = {
+	.probe = owl_socinfo_probe,
+	.driver = {
+		.name = "owl-socinfo",
+		.of_match_table = owl_socinfo_of_match,
+	},
+};
+
+static int __init owl_socinfo_init(void)
+{
+	return platform_driver_register(&owl_socinfo_platform_driver);
+}
+subsys_initcall(owl_socinfo_init);
diff --git a/include/linux/soc/actions/owl-serial-number.h b/include/linux/soc/actions/owl-serial-number.h
new file mode 100644
index 000000000000..f8595417668f
--- /dev/null
+++ b/include/linux/soc/actions/owl-serial-number.h
@@ -0,0 +1,20 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Copyright (c) 2021 Cristian Ciocaltea <cristian.ciocaltea@gmail.com>
+ */
+
+#ifndef __SOC_ACTIONS_OWL_SERIAL_NUMBER_H__
+#define __SOC_ACTIONS_OWL_SERIAL_NUMBER_H__
+
+#if IS_ENABLED(CONFIG_OWL_SOCINFO)
+u32 owl_get_soc_serial_low(void);
+u32 owl_get_soc_serial_high(void);
+#else
+static inline u32 owl_get_soc_serial_low(void)
+{ return 0; }
+
+static inline u32 owl_get_soc_serial_high(void)
+{ return 0; }
+#endif /* CONFIG_OWL_SOCINFO */
+
+#endif /* __SOC_ACTIONS_OWL_SERIAL_NUMBER_H__ */
-- 
2.31.1