drivers: soc: qcom: Add snapshot of virtual subsystem notification driver

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"

-reg : The start and size of the virtual device's

	register set.

-reg-names :  Should be "vdev_base" for virtual device's

	base address.

[Child nodes]

-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.

-type : The type of the subsystem.

	"virtual" - When the subsystem is loaded by the host VM

	"native" - When the subsystem is loaded by the guest VM

Required Property for "virtual" subsystem types:

-interrupts : Tuple defining the interrupt which the driver must

		register for to receive subsystem state notifications

		from the backend.

-interrupt-names: Must be "state-irq"

Example:

	subsys_notif_virt: qcom,subsys_notif_virt@2D000000 {

		compatible = "qcom,subsys-notif-virt";

		reg = <0x2D000000 0x400>;

		reg-names = "vdev_base";

		adsp {

			subsys-name = "adsp";

			interrupts = <0 43 0>;

			interrupt-names = "state-irq";

			type = "virtual";

			offset = <0>;

		};

		mpss {

			subsys-name = "modem";

			type = "native";

			offset = <256>;

		};

	};

/* Copyright (c) 2019, 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/of_irq.h>

#include <linux/platform_device.h>

#include <linux/interrupt.h>

#include <linux/workqueue.h>

#include <soc/qcom/subsystem_notif.h>

#define CLIENT_STATE_OFFSET 4

#define SUBSYS_STATE_OFFSET 8

static void __iomem *base_reg;

enum subsystem_type {

	VIRTUAL,

	NATIVE,

};

struct subsystem_descriptor {

	const char *name;

	u32 offset;

	enum subsystem_type type;

	struct notifier_block nb;

	void *handle;

	int ssr_irq;

	struct list_head subsystem_list;

	struct work_struct work;

};

static LIST_HEAD(subsystem_descriptor_list);

static struct workqueue_struct *ssr_wq;

static void subsystem_notif_wq_func(struct work_struct *work)

{

	struct subsystem_descriptor *subsystem =

		container_of(work, struct subsystem_descriptor, work);

	void *subsystem_handle;

	int state, ret;

	state = readl_relaxed(base_reg + subsystem->offset);

	subsystem_handle = subsys_notif_add_subsys(subsystem->name);

	ret = subsys_notif_queue_notification(subsystem_handle, state, NULL);

	writel_relaxed(ret, base_reg + subsystem->offset + CLIENT_STATE_OFFSET);

}

static int subsystem_state_callback(struct notifier_block *this,

		unsigned long value, void *priv)

{

	struct subsystem_descriptor *subsystem =

		container_of(this, struct subsystem_descriptor, nb);

	writel_relaxed(value, base_reg + subsystem->offset +

			SUBSYS_STATE_OFFSET);

	return NOTIFY_OK;

}

static irqreturn_t subsystem_restart_irq_handler(int irq, void *dev_id)

{

	struct subsystem_descriptor *subsystem = dev_id;

	queue_work(ssr_wq, &subsystem->work);

	return IRQ_HANDLED;

}

static int get_resources(struct platform_device *pdev)

{

	struct device_node *node;

	struct device_node *child = NULL;

	const char *ss_type;

	struct resource *res;

	struct subsystem_descriptor *subsystem = NULL;

	int ret = 0;

	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;

	}

	node = pdev->dev.of_node;

	for_each_child_of_node(node, child) {

		subsystem = devm_kmalloc(&pdev->dev,

				sizeof(struct subsystem_descriptor),

				GFP_KERNEL);

		if (!subsystem)

			return -ENOMEM;

		subsystem->name =

			of_get_property(child, "subsys-name", NULL);

		if (IS_ERR_OR_NULL(subsystem->name)) {

			dev_err(&pdev->dev, "Could not find subsystem name\n");

			return -EINVAL;

		}

		ret = of_property_read_u32(child, "offset",

				&subsystem->offset);

		if (ret) {

			dev_err(&pdev->dev, "offset reading for %s failed\n",

					subsystem->name);

			return -EINVAL;

		}

		ret = of_property_read_string(child, "type",

				&ss_type);

		if (ret) {

			dev_err(&pdev->dev, "type reading for %s failed\n",

					subsystem->name);

			return -EINVAL;

		}

		if (!strcmp(ss_type, "virtual"))

			subsystem->type = VIRTUAL;

		if (!strcmp(ss_type, "native"))

			subsystem->type = NATIVE;

		switch (subsystem->type) {

		case NATIVE:

			subsystem->nb.notifier_call =

				subsystem_state_callback;

			subsystem->handle =

				subsys_notif_register_notifier(

					subsystem->name, &subsystem->nb);

			if (IS_ERR_OR_NULL(subsystem->handle)) {

				dev_err(&pdev->dev,

					"Could not register SSR notifier cb\n");

				return -EINVAL;

			}

			list_add_tail(&subsystem->subsystem_list,

					&subsystem_descriptor_list);

			break;

		case VIRTUAL:

			subsystem->ssr_irq =

				of_irq_get_byname(child, "state-irq");

			if (subsystem->ssr_irq < 0) {

				dev_err(&pdev->dev, "Could not find IRQ\n");

				return -EINVAL;

			}

			ret = devm_request_threaded_irq(&pdev->dev,

					subsystem->ssr_irq, NULL,

					subsystem_restart_irq_handler,

					IRQF_ONESHOT | IRQF_TRIGGER_RISING,

					subsystem->name, subsystem);

			INIT_WORK(&subsystem->work, subsystem_notif_wq_func);

			break;

		default:

			dev_err(&pdev->dev, "Unsupported type %d\n",

				subsystem->type);

		}

	}

	return 0;

}

static void release_resources(void)

{

	struct subsystem_descriptor *subsystem, *node;

	list_for_each_entry_safe(subsystem, node, &subsystem_descriptor_list,

			subsystem_list) {

		subsys_notif_unregister_notifier(subsystem->handle,

				&subsystem->nb);

		list_del(&subsystem->subsystem_list);

	}

}

static int subsys_notif_virt_probe(struct platform_device *pdev)

{

	int ret = 0;

	if (!pdev) {

		dev_err(&pdev->dev, "pdev is NULL\n");

		return -EINVAL;

	}

	ssr_wq = create_singlethread_workqueue("ssr_wq");

	if (!ssr_wq) {

		dev_err(&pdev->dev, "Workqueue creation failed\n");

		return -ENOMEM;

	}

	ret = get_resources(pdev);

	if (ret)

		destroy_workqueue(ssr_wq);

	return ret;

}

static int subsys_notif_virt_remove(struct platform_device *pdev)

{

	destroy_workqueue(ssr_wq);

	release_resources();

	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");