1 files changed, 322 insertions, 0 deletions
diff --git a/drivers/platform/surface/surface_aggregator_cdev.c b/drivers/platform/surface/surface_aggregator_cdev.c
new file mode 100644
index 000000000000..79e28fab7e40
--- /dev/null
+++ b/drivers/platform/surface/surface_aggregator_cdev.c
@@ -0,0 +1,322 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Provides user-space access to the SSAM EC via the /dev/surface/aggregator
+ * misc device. Intended for debugging and development.
+ *
+ * Copyright (C) 2020 Maximilian Luz <luzmaximilian@gmail.com>
+ */
+
+#include <linux/fs.h>
+#include <linux/kernel.h>
+#include <linux/kref.h>
+#include <linux/miscdevice.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/rwsem.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+
+#include <linux/surface_aggregator/cdev.h>
+#include <linux/surface_aggregator/controller.h>
+
+#define SSAM_CDEV_DEVICE_NAME	"surface_aggregator_cdev"
+
+struct ssam_cdev {
+	struct kref kref;
+	struct rw_semaphore lock;
+	struct ssam_controller *ctrl;
+	struct miscdevice mdev;
+};
+
+static void __ssam_cdev_release(struct kref *kref)
+{
+	kfree(container_of(kref, struct ssam_cdev, kref));
+}
+
+static struct ssam_cdev *ssam_cdev_get(struct ssam_cdev *cdev)
+{
+	if (cdev)
+		kref_get(&cdev->kref);
+
+	return cdev;
+}
+
+static void ssam_cdev_put(struct ssam_cdev *cdev)
+{
+	if (cdev)
+		kref_put(&cdev->kref, __ssam_cdev_release);
+}
+
+static int ssam_cdev_device_open(struct inode *inode, struct file *filp)
+{
+	struct miscdevice *mdev = filp->private_data;
+	struct ssam_cdev *cdev = container_of(mdev, struct ssam_cdev, mdev);
+
+	filp->private_data = ssam_cdev_get(cdev);
+	return stream_open(inode, filp);
+}
+
+static int ssam_cdev_device_release(struct inode *inode, struct file *filp)
+{
+	ssam_cdev_put(filp->private_data);
+	return 0;
+}
+
+static long ssam_cdev_request(struct ssam_cdev *cdev, unsigned long arg)
+{
+	struct ssam_cdev_request __user *r;
+	struct ssam_cdev_request rqst;
+	struct ssam_request spec = {};
+	struct ssam_response rsp = {};
+	const void __user *plddata;
+	void __user *rspdata;
+	int status = 0, ret = 0, tmp;
+
+	r = (struct ssam_cdev_request __user *)arg;
+	ret = copy_struct_from_user(&rqst, sizeof(rqst), r, sizeof(*r));
+	if (ret)
+		goto out;
+
+	plddata = u64_to_user_ptr(rqst.payload.data);
+	rspdata = u64_to_user_ptr(rqst.response.data);
+
+	/* Setup basic request fields. */
+	spec.target_category = rqst.target_category;
+	spec.target_id = rqst.target_id;
+	spec.command_id = rqst.command_id;
+	spec.instance_id = rqst.instance_id;
+	spec.flags = 0;
+	spec.length = rqst.payload.length;
+	spec.payload = NULL;
+
+	if (rqst.flags & SSAM_CDEV_REQUEST_HAS_RESPONSE)
+		spec.flags |= SSAM_REQUEST_HAS_RESPONSE;
+
+	if (rqst.flags & SSAM_CDEV_REQUEST_UNSEQUENCED)
+		spec.flags |= SSAM_REQUEST_UNSEQUENCED;
+
+	rsp.capacity = rqst.response.length;
+	rsp.length = 0;
+	rsp.pointer = NULL;
+
+	/* Get request payload from user-space. */
+	if (spec.length) {
+		if (!plddata) {
+			ret = -EINVAL;
+			goto out;
+		}
+
+		/*
+		 * Note: spec.length is limited to U16_MAX bytes via struct
+		 * ssam_cdev_request. This is slightly larger than the
+		 * theoretical maximum (SSH_COMMAND_MAX_PAYLOAD_SIZE) of the
+		 * underlying protocol (note that nothing remotely this size
+		 * should ever be allocated in any normal case). This size is
+		 * validated later in ssam_request_sync(), for allocation the
+		 * bound imposed by u16 should be enough.
+		 */
+		spec.payload = kzalloc(spec.length, GFP_KERNEL);
+		if (!spec.payload) {
+			ret = -ENOMEM;
+			goto out;
+		}
+
+		if (copy_from_user((void *)spec.payload, plddata, spec.length)) {
+			ret = -EFAULT;
+			goto out;
+		}
+	}
+
+	/* Allocate response buffer. */
+	if (rsp.capacity) {
+		if (!rspdata) {
+			ret = -EINVAL;
+			goto out;
+		}
+
+		/*
+		 * Note: rsp.capacity is limited to U16_MAX bytes via struct
+		 * ssam_cdev_request. This is slightly larger than the
+		 * theoretical maximum (SSH_COMMAND_MAX_PAYLOAD_SIZE) of the
+		 * underlying protocol (note that nothing remotely this size
+		 * should ever be allocated in any normal case). In later use,
+		 * this capacity does not have to be strictly bounded, as it
+		 * is only used as an output buffer to be written to. For
+		 * allocation the bound imposed by u16 should be enough.
+		 */
+		rsp.pointer = kzalloc(rsp.capacity, GFP_KERNEL);
+		if (!rsp.pointer) {
+			ret = -ENOMEM;
+			goto out;
+		}
+	}
+
+	/* Perform request. */
+	status = ssam_request_sync(cdev->ctrl, &spec, &rsp);
+	if (status)
+		goto out;
+
+	/* Copy response to user-space. */
+	if (rsp.length && copy_to_user(rspdata, rsp.pointer, rsp.length))
+		ret = -EFAULT;
+
+out:
+	/* Always try to set response-length and status. */
+	tmp = put_user(rsp.length, &r->response.length);
+	if (tmp)
+		ret = tmp;
+
+	tmp = put_user(status, &r->status);
+	if (tmp)
+		ret = tmp;
+
+	/* Cleanup. */
+	kfree(spec.payload);
+	kfree(rsp.pointer);
+
+	return ret;
+}
+
+static long __ssam_cdev_device_ioctl(struct ssam_cdev *cdev, unsigned int cmd,
+				     unsigned long arg)
+{
+	switch (cmd) {
+	case SSAM_CDEV_REQUEST:
+		return ssam_cdev_request(cdev, arg);
+
+	default:
+		return -ENOTTY;
+	}
+}
+
+static long ssam_cdev_device_ioctl(struct file *file, unsigned int cmd,
+				   unsigned long arg)
+{
+	struct ssam_cdev *cdev = file->private_data;
+	long status;
+
+	/* Ensure that controller is valid for as long as we need it. */
+	if (down_read_killable(&cdev->lock))
+		return -ERESTARTSYS;
+
+	if (!cdev->ctrl) {
+		up_read(&cdev->lock);
+		return -ENODEV;
+	}
+
+	status = __ssam_cdev_device_ioctl(cdev, cmd, arg);
+
+	up_read(&cdev->lock);
+	return status;
+}
+
+static const struct file_operations ssam_controller_fops = {
+	.owner          = THIS_MODULE,
+	.open           = ssam_cdev_device_open,
+	.release        = ssam_cdev_device_release,
+	.unlocked_ioctl = ssam_cdev_device_ioctl,
+	.compat_ioctl   = ssam_cdev_device_ioctl,
+	.llseek         = noop_llseek,
+};
+
+static int ssam_dbg_device_probe(struct platform_device *pdev)
+{
+	struct ssam_controller *ctrl;
+	struct ssam_cdev *cdev;
+	int status;
+
+	ctrl = ssam_client_bind(&pdev->dev);
+	if (IS_ERR(ctrl))
+		return PTR_ERR(ctrl) == -ENODEV ? -EPROBE_DEFER : PTR_ERR(ctrl);
+
+	cdev = kzalloc(sizeof(*cdev), GFP_KERNEL);
+	if (!cdev)
+		return -ENOMEM;
+
+	kref_init(&cdev->kref);
+	init_rwsem(&cdev->lock);
+	cdev->ctrl = ctrl;
+
+	cdev->mdev.parent   = &pdev->dev;
+	cdev->mdev.minor    = MISC_DYNAMIC_MINOR;
+	cdev->mdev.name     = "surface_aggregator";
+	cdev->mdev.nodename = "surface/aggregator";
+	cdev->mdev.fops     = &ssam_controller_fops;
+
+	status = misc_register(&cdev->mdev);
+	if (status) {
+		kfree(cdev);
+		return status;
+	}
+
+	platform_set_drvdata(pdev, cdev);
+	return 0;
+}
+
+static int ssam_dbg_device_remove(struct platform_device *pdev)
+{
+	struct ssam_cdev *cdev = platform_get_drvdata(pdev);
+
+	misc_deregister(&cdev->mdev);
+
+	/*
+	 * The controller is only guaranteed to be valid for as long as the
+	 * driver is bound. Remove controller so that any lingering open files
+	 * cannot access it any more after we're gone.
+	 */
+	down_write(&cdev->lock);
+	cdev->ctrl = NULL;
+	up_write(&cdev->lock);
+
+	ssam_cdev_put(cdev);
+	return 0;
+}
+
+static struct platform_device *ssam_cdev_device;
+
+static struct platform_driver ssam_cdev_driver = {
+	.probe = ssam_dbg_device_probe,
+	.remove = ssam_dbg_device_remove,
+	.driver = {
+		.name = SSAM_CDEV_DEVICE_NAME,
+		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
+	},
+};
+
+static int __init ssam_debug_init(void)
+{
+	int status;
+
+	ssam_cdev_device = platform_device_alloc(SSAM_CDEV_DEVICE_NAME,
+						 PLATFORM_DEVID_NONE);
+	if (!ssam_cdev_device)
+		return -ENOMEM;
+
+	status = platform_device_add(ssam_cdev_device);
+	if (status)
+		goto err_device;
+
+	status = platform_driver_register(&ssam_cdev_driver);
+	if (status)
+		goto err_driver;
+
+	return 0;
+
+err_driver:
+	platform_device_del(ssam_cdev_device);
+err_device:
+	platform_device_put(ssam_cdev_device);
+	return status;
+}
+module_init(ssam_debug_init);
+
+static void __exit ssam_debug_exit(void)
+{
+	platform_driver_unregister(&ssam_cdev_driver);
+	platform_device_unregister(ssam_cdev_device);
+}
+module_exit(ssam_debug_exit);
+
+MODULE_AUTHOR("Maximilian Luz <luzmaximilian@gmail.com>");
+MODULE_DESCRIPTION("User-space interface for Surface System Aggregator Module");
+MODULE_LICENSE("GPL");