[PATCH 2/4] soc: actions: Add Actions Semi Owl socinfo driver

[Cristian Ciocaltea]

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@xxxxxxxxx>
---
 drivers/soc/actions/Kconfig       |   8 ++
 drivers/soc/actions/Makefile      |   1 +
 drivers/soc/actions/owl-socinfo.c | 133 ++++++++++++++++++++++++++++++
 3 files changed, 142 insertions(+)
 create mode 100644 drivers/soc/actions/owl-socinfo.c

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..2786c4fd261c
--- /dev/null
+++ b/drivers/soc/actions/owl-socinfo.c
@@ -0,0 +1,133 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Actions Semi Owl SoC information driver
+ *
+ * Copyright (c) 2021 Cristian Ciocaltea <cristian.ciocaltea@xxxxxxxxx>
+ */
+
+#include <linux/highmem.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/random.h>
+#include <linux/sys_soc.h>
+
+#include <asm/system_info.h>
+
+struct owl_soc_info {
+	char *name;
+	int (*get_system_serial)(struct device *dev);
+};
+
+static int __init owl_read_sn_from_mem(struct device *dev)
+{
+	int paddrs[2] = {0};
+	char *vaddr;
+	int ret;
+
+	ret = device_property_read_u32_array(dev,
+					     "actions,serial-number-addrs",
+					     paddrs, 2);
+	if (ret) {
+		dev_err(dev, "failed to read SoC S/N addresses: %d\n", ret);
+		return ret;
+	}
+
+	if (PHYS_PFN(paddrs[0]) != PHYS_PFN(paddrs[1])) {
+		dev_err(dev, "invalid SoC S/N addresses\n");
+		return -EINVAL;
+	}
+
+	vaddr = kmap_local_pfn(PHYS_PFN(paddrs[0]));
+
+	memcpy(&system_serial_low, vaddr + (paddrs[0] & (PAGE_SIZE - 1)),
+	       sizeof(system_serial_low));
+	memcpy(&system_serial_high, vaddr + (paddrs[1] & (PAGE_SIZE - 1)),
+	       sizeof(system_serial_high));
+
+	kunmap_local(vaddr);
+
+	return 0;
+}
+
+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;
+	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->get_system_serial) {
+		ret = soc_info->get_system_serial(&pdev->dev);
+		if (!ret) {
+			soc_dev_attr->serial_number = devm_kasprintf(&pdev->dev,
+						GFP_KERNEL, "%08x%08x",
+						system_serial_high,
+						system_serial_low);
+			/* Feed the SoC unique data into entropy pool. */
+			add_device_randomness(soc_dev_attr->serial_number, 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",
+	.get_system_serial = owl_read_sn_from_mem,
+};
+
+static const struct owl_soc_info s700_soc_info = {
+	.name = "S700",
+	/* FIXME: provide get_system_serial */
+};
+
+static const struct owl_soc_info s900_soc_info = {
+	.name = "S900",
+	/* FIXME: provide get_system_serial */
+};
+
+static const struct of_device_id owl_soc_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_soc_of_match,
+	},
+};
+
+static int __init owl_socinfo_init(void)
+{
+	return platform_driver_register(&owl_socinfo_platform_driver);
+}
+subsys_initcall(owl_socinfo_init);
-- 
2.31.0