soc: qcom: subsystem_notif_virt: Add virtual subsystem notification driver

The guest VM uses this driver to communicate subsystem state related
notifications to a backend driver via the virtual device's registers.

Change-Id: I612fcb641c4d531c1d2c0fd18f44f7ebff040f2c
Signed-off-by: Anant Goel <anantg@codeaurora.org>

3 files changed, 199 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/arm/msm/subsystem_notif_virt.txt b/Documentation/devicetree/bindings/arm/msm/subsystem_notif_virt.txt
new file mode 100644
index 000000000000..50fffbe8284c
--- /dev/null
+++ b/Documentation/devicetree/bindings/arm/msm/subsystem_notif_virt.txt
@@ -0,0 +1,35 @@
+Subsystem Notification Virtual Driver
+
+The guest VM uses this driver to communicate
+subsystem state notifications to a backend driver
+via the virtual device's registers.
+
+[Root level node]
+Required Properties:
+-compatible : Should be "qcom,subsys-notif-virt"
+	for notifications regarding state.
+-reg : The start and size of the virtual device's
+	register set.
+-reg-names :  Should be "vdev_base" for virtual device's
+	base address.
+-subsys-names : The name of the subsystem that the
+	driver is registering to notifications for.
+-offset : The offset from the virtual device's register
+	base where the subsystem state will be written.
+
+Example:
+
+	subsys_notif_virt: qcom,subsys_notif_virt@2D000000 {
+		compatible = "qcom,subsys-notif-virt";
+		reg = <0x2D000000 0x10>;
+		reg-names = "vdev_base";
+		adsp {
+			subsys-name = "adsp";
+			offset = <0>;
+		};
+		mpss {
+			subsys-name = "modem";
+			offset = <8>;
+		};
+	};
+
diff --git a/drivers/soc/qcom/Makefile b/drivers/soc/qcom/Makefile
index ba2ff8326cac..8605b750c11d 100644
--- a/drivers/soc/qcom/Makefile
+++ b/drivers/soc/qcom/Makefile
@@ -47,6 +47,7 @@ ifdef CONFIG_MSM_SUBSYSTEM_RESTART
 	obj-y += subsystem_notif.o
 	obj-y += subsystem_restart.o
 	obj-y += ramdump.o
+	obj-$(CONFIG_MSM_GVM_QUIN) += subsystem_notif_virt.o
 endif
 
 obj-$(CONFIG_QPNP_HAPTIC) += qpnp-haptic.o
diff --git a/drivers/soc/qcom/subsystem_notif_virt.c b/drivers/soc/qcom/subsystem_notif_virt.c
new file mode 100644
index 000000000000..739600f2498d
--- /dev/null
+++ b/drivers/soc/qcom/subsystem_notif_virt.c
@@ -0,0 +1,163 @@
+/* Copyright (c) 2018, The Linux Foundation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/err.h>
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/notifier.h>
+#include <linux/list.h>
+#include <linux/slab.h>
+#include <linux/of.h>
+#include <linux/io.h>
+#include <linux/of_platform.h>
+#include <linux/of_device.h>
+#include <linux/of_address.h>
+#include <linux/platform_device.h>
+#include <soc/qcom/subsystem_notif.h>
+
+static void __iomem *base_reg;
+
+struct state_notifier_block {
+	const char *subsystem;
+	struct notifier_block nb;
+	u32 offset;
+	void *handle;
+	struct list_head notifier_list;
+};
+
+static LIST_HEAD(notifier_block_list);
+
+static int subsys_state_callback(struct notifier_block *this,
+		unsigned long value, void *priv)
+{
+	struct state_notifier_block *notifier =
+		container_of(this, struct state_notifier_block, nb);
+
+	writel_relaxed(value, base_reg + notifier->offset);
+
+	return NOTIFY_OK;
+}
+
+static int subsys_notif_virt_probe(struct platform_device *pdev)
+{
+	struct device_node *node;
+	struct device_node *child = NULL;
+	struct resource *res;
+	struct state_notifier_block *notif_block;
+	int ret = 0;
+
+	if (!pdev) {
+		dev_err(&pdev->dev, "pdev is NULL\n");
+		return -EINVAL;
+	}
+
+	node = pdev->dev.of_node;
+
+	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "vdev_base");
+	base_reg = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR_OR_NULL(base_reg)) {
+		dev_err(&pdev->dev, "Memory mapping failed\n");
+		return -ENOMEM;
+	}
+
+	for_each_child_of_node(node, child) {
+
+		notif_block = devm_kmalloc(&pdev->dev,
+				sizeof(struct state_notifier_block),
+				GFP_KERNEL);
+		if (!notif_block)
+			return -ENOMEM;
+
+		notif_block->subsystem =
+				of_get_property(child, "subsys-name", NULL);
+		if (IS_ERR_OR_NULL(notif_block->subsystem)) {
+			dev_err(&pdev->dev, "Could not find subsystem name\n");
+			ret = -EINVAL;
+			goto err_nb;
+		}
+
+		notif_block->nb.notifier_call = subsys_state_callback;
+
+		notif_block->handle =
+			subsys_notif_register_notifier(notif_block->subsystem,
+				&notif_block->nb);
+		if (IS_ERR_OR_NULL(notif_block->handle)) {
+			dev_err(&pdev->dev, "Could not register SSR notifier cb\n");
+			ret = -EINVAL;
+			goto err_nb;
+		}
+
+		ret = of_property_read_u32(child, "offset",
+				&notif_block->offset);
+		if (ret) {
+			dev_err(&pdev->dev, "offset reading for %s failed\n",
+				notif_block->subsystem);
+			ret = -EINVAL;
+			goto err_offset;
+		}
+
+		list_add_tail(&notif_block->notifier_list,
+			&notifier_block_list);
+
+	}
+	return 0;
+
+err_offset:
+	subsys_notif_unregister_notifier(notif_block->handle,
+		&notif_block->nb);
+err_nb:
+	kfree(notif_block);
+	return ret;
+}
+
+static int subsys_notif_virt_remove(struct platform_device *pdev)
+{
+	struct state_notifier_block *notif_block;
+
+	list_for_each_entry(notif_block, &notifier_block_list,
+			notifier_list) {
+		subsys_notif_unregister_notifier(notif_block->handle,
+			&notif_block->nb);
+		list_del(&notif_block->notifier_list);
+	}
+	return 0;
+}
+
+static const struct of_device_id match_table[] = {
+	{ .compatible = "qcom,subsys-notif-virt" },
+	{},
+};
+
+static struct platform_driver subsys_notif_virt_driver = {
+	.probe = subsys_notif_virt_probe,
+	.remove = subsys_notif_virt_remove,
+	.driver = {
+		.name = "subsys_notif_virt",
+		.owner = "THIS_MODULE",
+		.of_match_table = match_table,
+	},
+};
+
+static int __init subsys_notif_virt_init(void)
+{
+	return platform_driver_register(&subsys_notif_virt_driver);
+}
+module_init(subsys_notif_virt_init);
+
+static void __exit subsys_notif_virt_exit(void)
+{
+	platform_driver_unregister(&subsys_notif_virt_driver);
+}
+module_exit(subsys_notif_virt_exit);
+
+MODULE_DESCRIPTION("Subsystem Notification Virtual Driver");
+MODULE_LICENSE("GPL v2");