* Copyright (C) 2017 Oracle. All rights reserved.
*/
+#include <linux/delay.h>
+#include <linux/interrupt.h>
#include <linux/module.h>
+#include <linux/slab.h>
#include <linux/tty.h>
+#include <asm/vio.h>
+#include <asm/ldc.h>
#define DRV_MODULE_NAME "vcc"
#define DRV_MODULE_VERSION "1.1"
MODULE_LICENSE("GPL");
MODULE_VERSION(DRV_MODULE_VERSION);
+struct vcc_port {
+ struct vio_driver_state vio;
+
+ spinlock_t lock;
+ char *domain;
+ struct tty_struct *tty; /* only populated while dev is open */
+ unsigned long index; /* index into the vcc_table */
+
+ u64 refcnt;
+ bool excl_locked;
+
+ bool removed;
+
+ /* This buffer is required to support the tty write_room interface
+ * and guarantee that any characters that the driver accepts will
+ * be eventually sent, either immediately or later.
+ */
+ int chars_in_buffer;
+ struct vio_vcc buffer;
+
+ struct timer_list rx_timer;
+ struct timer_list tx_timer;
+};
+
+/* Microseconds that thread will delay waiting for a vcc port ref */
+#define VCC_REF_DELAY 100
+
#define VCC_MAX_PORTS 1024
#define VCC_MINOR_START 0 /* must be zero */
static const char vcc_device_node[] = "vcc";
static struct tty_driver *vcc_tty_driver;
+static struct vcc_port *vcc_table[VCC_MAX_PORTS];
+static DEFINE_SPINLOCK(vcc_table_lock);
+
int vcc_dbg;
int vcc_dbg_ldc;
int vcc_dbg_vio;
.c_ospeed = 38400
};
+/**
+ * vcc_table_add() - Add VCC port to the VCC table
+ * @port: pointer to the VCC port
+ *
+ * Return: index of the port in the VCC table on success,
+ * -1 on failure
+ */
+static int vcc_table_add(struct vcc_port *port)
+{
+ unsigned long flags;
+ int i;
+
+ spin_lock_irqsave(&vcc_table_lock, flags);
+ for (i = VCC_MINOR_START; i < VCC_MAX_PORTS; i++) {
+ if (!vcc_table[i]) {
+ vcc_table[i] = port;
+ break;
+ }
+ }
+ spin_unlock_irqrestore(&vcc_table_lock, flags);
+
+ if (i < VCC_MAX_PORTS)
+ return i;
+ else
+ return -1;
+}
+
+/**
+ * vcc_table_remove() - Removes a VCC port from the VCC table
+ * @index: Index into the VCC table
+ */
+static void vcc_table_remove(unsigned long index)
+{
+ unsigned long flags;
+
+ if (WARN_ON(index >= VCC_MAX_PORTS))
+ return;
+
+ spin_lock_irqsave(&vcc_table_lock, flags);
+ vcc_table[index] = NULL;
+ spin_unlock_irqrestore(&vcc_table_lock, flags);
+}
+
+/**
+ * vcc_get() - Gets a reference to VCC port
+ * @index: Index into the VCC table
+ * @excl: Indicates if an exclusive access is requested
+ *
+ * Return: reference to the VCC port, if found
+ * NULL, if port not found
+ */
+static struct vcc_port *vcc_get(unsigned long index, bool excl)
+{
+ struct vcc_port *port;
+ unsigned long flags;
+
+try_again:
+ spin_lock_irqsave(&vcc_table_lock, flags);
+
+ port = vcc_table[index];
+ if (!port) {
+ spin_unlock_irqrestore(&vcc_table_lock, flags);
+ return NULL;
+ }
+
+ if (!excl) {
+ if (port->excl_locked) {
+ spin_unlock_irqrestore(&vcc_table_lock, flags);
+ udelay(VCC_REF_DELAY);
+ goto try_again;
+ }
+ port->refcnt++;
+ spin_unlock_irqrestore(&vcc_table_lock, flags);
+ return port;
+ }
+
+ if (port->refcnt) {
+ spin_unlock_irqrestore(&vcc_table_lock, flags);
+ /* Threads wanting exclusive access will wait half the time,
+ * probably giving them higher priority in the case of
+ * multiple waiters.
+ */
+ udelay(VCC_REF_DELAY/2);
+ goto try_again;
+ }
+
+ port->refcnt++;
+ port->excl_locked = true;
+ spin_unlock_irqrestore(&vcc_table_lock, flags);
+
+ return port;
+}
+
+/**
+ * vcc_put() - Returns a reference to VCC port
+ * @port: pointer to VCC port
+ * @excl: Indicates if the returned reference is an exclusive reference
+ *
+ * Note: It's the caller's responsibility to ensure the correct value
+ * for the excl flag
+ */
+static void vcc_put(struct vcc_port *port, bool excl)
+{
+ unsigned long flags;
+
+ if (!port)
+ return;
+
+ spin_lock_irqsave(&vcc_table_lock, flags);
+
+ /* check if caller attempted to put with the wrong flags */
+ if (WARN_ON((excl && !port->excl_locked) ||
+ (!excl && port->excl_locked)))
+ goto done;
+
+ port->refcnt--;
+
+ if (excl)
+ port->excl_locked = false;
+
+done:
+ spin_unlock_irqrestore(&vcc_table_lock, flags);
+}
+
+/**
+ * vcc_get_ne() - Get a non-exclusive reference to VCC port
+ * @index: Index into the VCC table
+ *
+ * Gets a non-exclusive reference to VCC port, if it's not removed
+ *
+ * Return: pointer to the VCC port, if found
+ * NULL, if port not found
+ */
+static struct vcc_port *vcc_get_ne(unsigned long index)
+{
+ struct vcc_port *port;
+
+ port = vcc_get(index, false);
+
+ if (port && port->removed) {
+ vcc_put(port, false);
+ return NULL;
+ }
+
+ return port;
+}
+
+static void vcc_event(void *arg, int event)
+{
+}
+
+static struct ldc_channel_config vcc_ldc_cfg = {
+ .event = vcc_event,
+ .mtu = VIO_VCC_MTU_SIZE,
+ .mode = LDC_MODE_RAW,
+ .debug = 0,
+};
+
+/* Ordered from largest major to lowest */
+static struct vio_version vcc_versions[] = {
+ { .major = 1, .minor = 0 },
+};
+
+/**
+ * vcc_probe() - Initialize VCC port
+ * @vdev: Pointer to VIO device of the new VCC port
+ * @id: VIO device ID
+ *
+ * Initializes a VCC port to receive serial console data from
+ * the guest domain. Sets up a TTY end point on the control
+ * domain. Sets up VIO/LDC link between the guest & control
+ * domain endpoints.
+ *
+ * Return: status of the probe
+ */
+static int vcc_probe(struct vio_dev *vdev, const struct vio_device_id *id)
+{
+ struct mdesc_handle *hp;
+ struct vcc_port *port;
+ struct device *dev;
+ const char *domain;
+ char *name;
+ u64 node;
+ int rv;
+
+ vccdbg("VCC: name=%s\n", dev_name(&vdev->dev));
+
+ if (!vcc_tty_driver) {
+ pr_err("VCC: TTY driver not registered\n");
+ return -ENODEV;
+ }
+
+ port = kzalloc(sizeof(struct vcc_port), GFP_KERNEL);
+ if (!port)
+ return -ENOMEM;
+
+ name = kstrdup(dev_name(&vdev->dev), GFP_KERNEL);
+
+ rv = vio_driver_init(&port->vio, vdev, VDEV_CONSOLE_CON, vcc_versions,
+ ARRAY_SIZE(vcc_versions), NULL, name);
+ if (rv)
+ goto free_port;
+
+ port->vio.debug = vcc_dbg_vio;
+ vcc_ldc_cfg.debug = vcc_dbg_ldc;
+
+ rv = vio_ldc_alloc(&port->vio, &vcc_ldc_cfg, port);
+ if (rv)
+ goto free_port;
+
+ spin_lock_init(&port->lock);
+
+ port->index = vcc_table_add(port);
+ if (port->index == -1) {
+ pr_err("VCC: no more TTY indices left for allocation\n");
+ goto free_ldc;
+ }
+
+ /* Register the device using VCC table index as TTY index */
+ dev = tty_register_device(vcc_tty_driver, port->index, &vdev->dev);
+ if (IS_ERR(dev)) {
+ rv = PTR_ERR(dev);
+ goto free_table;
+ }
+
+ hp = mdesc_grab();
+
+ node = vio_vdev_node(hp, vdev);
+ if (node == MDESC_NODE_NULL) {
+ rv = -ENXIO;
+ mdesc_release(hp);
+ goto unreg_tty;
+ }
+
+ domain = mdesc_get_property(hp, node, "vcc-domain-name", NULL);
+ if (!domain) {
+ rv = -ENXIO;
+ mdesc_release(hp);
+ goto unreg_tty;
+ }
+ port->domain = kstrdup(domain, GFP_KERNEL);
+
+ mdesc_release(hp);
+
+ dev_set_drvdata(&vdev->dev, port);
+
+ /* It's possible to receive IRQs in the middle of vio_port_up. Disable
+ * IRQs until the port is up.
+ */
+ disable_irq_nosync(vdev->rx_irq);
+ vio_port_up(&port->vio);
+ enable_irq(vdev->rx_irq);
+
+ return 0;
+
+unreg_tty:
+ tty_unregister_device(vcc_tty_driver, port->index);
+free_table:
+ vcc_table_remove(port->index);
+free_ldc:
+ vio_ldc_free(&port->vio);
+free_port:
+ kfree(name);
+ kfree(port);
+
+ return rv;
+}
+
+/**
+ * vcc_remove() - Terminate a VCC port
+ * @vdev: Pointer to VIO device of the VCC port
+ *
+ * Terminates a VCC port. Sets up the teardown of TTY and
+ * VIO/LDC link between guest and primary domains.
+ *
+ * Return: status of removal
+ */
+static int vcc_remove(struct vio_dev *vdev)
+{
+ struct vcc_port *port = dev_get_drvdata(&vdev->dev);
+
+ if (!port)
+ return -ENODEV;
+
+ /* If there's a process with the device open, do a synchronous
+ * hangup of the TTY. This *may* cause the process to call close
+ * asynchronously, but it's not guaranteed.
+ */
+ if (port->tty)
+ tty_vhangup(port->tty);
+
+ /* Get exclusive reference to VCC, ensures that there are no other
+ * clients to this port
+ */
+ port = vcc_get(port->index, true);
+
+ if (WARN_ON(!port))
+ return -ENODEV;
+
+ tty_unregister_device(vcc_tty_driver, port->index);
+
+ del_timer_sync(&port->vio.timer);
+ vio_ldc_free(&port->vio);
+ dev_set_drvdata(&vdev->dev, NULL);
+
+ if (port->tty) {
+ port->removed = true;
+ vcc_put(port, true);
+ } else {
+ vcc_table_remove(port->index);
+
+ kfree(port->vio.name);
+ kfree(port->domain);
+ kfree(port);
+ }
+
+ return 0;
+}
+
+static const struct vio_device_id vcc_match[] = {
+ {
+ .type = "vcc-port",
+ },
+ {},
+};
+MODULE_DEVICE_TABLE(vio, vcc_match);
+
+static struct vio_driver vcc_driver = {
+ .id_table = vcc_match,
+ .probe = vcc_probe,
+ .remove = vcc_remove,
+ .name = "vcc",
+};
+
static const struct tty_operations vcc_ops;
#define VCC_TTY_FLAGS (TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_REAL_RAW)
return rv;
}
+ rv = vio_register_driver(&vcc_driver);
+ if (rv) {
+ pr_err("VCC: VIO driver registration failed\n");
+ vcc_tty_exit();
+ } else {
+ vccdbg("VCC: VIO driver registered successfully\n");
+ }
+
return rv;
}
static void __exit vcc_exit(void)
{
+ vio_unregister_driver(&vcc_driver);
+ vccdbg("VCC: VIO driver unregistered\n");
vcc_tty_exit();
vccdbg("VCC: TTY driver unregistered\n");
}
projects / platform / kernel / linux-exynos.git / commitdiff