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    Subject[PATCH v5 13/13] tty: gunyah: Add tty console driver for RM Console Services
    Date
    Gunyah provides a console for each VM using the VM console resource
    manager APIs. This driver allows console data from other
    VMs to be accessed via a TTY device and exports a console device to dump
    Linux's own logs to our console.

    Signed-off-by: Elliot Berman <quic_eberman@quicinc.com>
    ---
    MAINTAINERS | 1 +
    drivers/tty/Kconfig | 8 +
    drivers/tty/Makefile | 1 +
    drivers/tty/gunyah_console.c | 439 +++++++++++++++++++++++++++++++++++
    4 files changed, 449 insertions(+)
    create mode 100644 drivers/tty/gunyah_console.c

    diff --git a/MAINTAINERS b/MAINTAINERS
    index 8a3d79b56698..e85140fa0dfe 100644
    --- a/MAINTAINERS
    +++ b/MAINTAINERS
    @@ -8889,6 +8889,7 @@ F: Documentation/devicetree/bindings/firmware/gunyah-hypervisor.yaml
    F: Documentation/virt/gunyah/
    F: arch/arm64/gunyah/
    F: drivers/mailbox/gunyah-msgq.c
    +F: drivers/tty/gunyah_tty.c
    F: drivers/virt/gunyah/
    F: include/asm-generic/gunyah.h
    F: include/linux/gunyah*.h
    diff --git a/drivers/tty/Kconfig b/drivers/tty/Kconfig
    index cc30ff93e2e4..ff86e977f9ac 100644
    --- a/drivers/tty/Kconfig
    +++ b/drivers/tty/Kconfig
    @@ -380,6 +380,14 @@ config RPMSG_TTY
    To compile this driver as a module, choose M here: the module will be
    called rpmsg_tty.

    +config GUNYAH_CONSOLE
    + tristate "Gunyah Consoles"
    + depends on GUNYAH
    + help
    + This enables support for console output using Gunyah's Resource Manager RPC.
    + This is normally used when a secondary VM which does not have exclusive access
    + to a real or virtualized serial device and virtio-console is unavailable.
    +
    endif # TTY

    source "drivers/tty/serdev/Kconfig"
    diff --git a/drivers/tty/Makefile b/drivers/tty/Makefile
    index 07aca5184a55..134b7321c630 100644
    --- a/drivers/tty/Makefile
    +++ b/drivers/tty/Makefile
    @@ -27,5 +27,6 @@ obj-$(CONFIG_GOLDFISH_TTY) += goldfish.o
    obj-$(CONFIG_MIPS_EJTAG_FDC_TTY) += mips_ejtag_fdc.o
    obj-$(CONFIG_VCC) += vcc.o
    obj-$(CONFIG_RPMSG_TTY) += rpmsg_tty.o
    +obj-$(CONFIG_GUNYAH_CONSOLE) += gunyah_console.o

    obj-y += ipwireless/
    diff --git a/drivers/tty/gunyah_console.c b/drivers/tty/gunyah_console.c
    new file mode 100644
    index 000000000000..71d9f22c2a43
    --- /dev/null
    +++ b/drivers/tty/gunyah_console.c
    @@ -0,0 +1,439 @@
    +// SPDX-License-Identifier: GPL-2.0-only
    +/*
    + * Copyright (c) 2022 Qualcomm Innovation Center, Inc. All rights reserved.
    + */
    +
    +#include <linux/console.h>
    +#include <linux/kfifo.h>
    +#include <linux/kref.h>
    +#include <linux/gunyah_rsc_mgr.h>
    +#include <linux/module.h>
    +#include <linux/slab.h>
    +#include <linux/spinlock.h>
    +#include <linux/tty.h>
    +#include <linux/tty_flip.h>
    +#include <linux/workqueue.h>
    +
    +/*
    + * The Linux TTY code requires us to know ahead of time how many ports we might
    + * need. Each port here corresponds to a VM. 16 seems like a reasonable number
    + * of ports for systems that are running Gunyah and using the console interface.
    + */
    +#define RM_CONS_TTY_ADAPATERS (16)
    +
    +struct rm_cons_port {
    + struct tty_port port;
    + u16 vmid;
    + unsigned int index;
    +};
    +
    +struct rm_cons_drv_data {
    + struct tty_driver *tty_driver;
    + struct device *dev;
    +
    + spinlock_t ports_lock;
    + struct rm_cons_port *ports[RM_CONS_TTY_ADAPATERS];
    +
    + struct notifier_block rm_cons_notif;
    + struct console console;
    +
    + /* below are for printk console.
    + * gh_rm_console_* calls will sleep and console_write can be called from
    + * atomic ctx. Two xmit buffers are used. The active buffer is tracked with
    + * co_xmit_idx. Writes go into the co_xmit_buf[co_xmit_idx] buffer.
    + * A work is scheduled to flush the bytes. The work will swap the active buffer
    + * and write out the other buffer.
    + */
    + char *co_xmit_buf[2];
    + int co_xmit_idx;
    + unsigned int co_xmit_count;
    + spinlock_t co_xmit_lock;
    + struct work_struct co_flush_work;
    +};
    +
    +static int rm_cons_notif_handler(struct notifier_block *nb, unsigned long cmd, void *data)
    +{
    + int count, i;
    + struct rm_cons_port *rm_port = NULL;
    + struct tty_port *tty_port = NULL;
    + struct rm_cons_drv_data *cons_data =
    + container_of(nb, struct rm_cons_drv_data, rm_cons_notif);
    + const struct gh_rm_notification *notif = data;
    + struct gh_rm_notif_vm_console_chars const * const msg = notif->buff;
    +
    + if (cmd != GH_RM_NOTIF_VM_CONSOLE_CHARS ||
    + notif->size < sizeof(*msg))
    + return NOTIFY_DONE;
    +
    + spin_lock(&cons_data->ports_lock);
    + for (i = 0; i < RM_CONS_TTY_ADAPATERS; i++) {
    + if (!cons_data->ports[i])
    + continue;
    + if (cons_data->ports[i]->vmid == msg->vmid) {
    + rm_port = cons_data->ports[i];
    + break;
    + }
    + }
    + if (rm_port)
    + tty_port = tty_port_get(&rm_port->port);
    + spin_unlock(&cons_data->ports_lock);
    +
    + if (!rm_port)
    + dev_warn(cons_data->dev, "Received unexpected console characters for VMID %u\n",
    + msg->vmid);
    + if (!tty_port)
    + return NOTIFY_DONE;
    +
    + count = tty_buffer_request_room(tty_port, msg->num_bytes);
    + tty_insert_flip_string(tty_port, msg->bytes, count);
    + tty_flip_buffer_push(tty_port);
    +
    + tty_port_put(tty_port);
    + return NOTIFY_OK;
    +}
    +
    +static int rm_cons_tty_open(struct tty_struct *tty, struct file *filp)
    +{
    + struct rm_cons_port *rm_port = dev_get_drvdata(tty->dev);
    +
    + return tty_port_open(&rm_port->port, tty, filp);
    +}
    +
    +static void rm_cons_tty_close(struct tty_struct *tty, struct file *filp)
    +{
    + struct rm_cons_port *rm_port = dev_get_drvdata(tty->dev);
    +
    + tty_port_close(&rm_port->port, tty, filp);
    +}
    +
    +static int rm_cons_tty_write(struct tty_struct *tty, const unsigned char *buf, int count)
    +{
    + struct rm_cons_port *rm_port = dev_get_drvdata(tty->dev);
    + int ret;
    +
    + if (!count)
    + return 0;
    +
    + ret = gh_rm_console_write(rm_port->vmid, buf, count);
    + if (ret)
    + return -EAGAIN;
    + return count;
    +}
    +
    +static void rm_cons_tty_flush_chars(struct tty_struct *tty)
    +{
    + struct rm_cons_port *rm_port = dev_get_drvdata(tty->dev);
    +
    + gh_rm_console_flush(rm_port->vmid);
    +}
    +
    +static unsigned int rm_cons_mgr_tty_write_room(struct tty_struct *tty)
    +{
    + return GH_RM_CONSOLE_WRITE_CHARS;
    +}
    +
    +static const struct tty_operations rm_cons_tty_ops = {
    + .open = rm_cons_tty_open,
    + .close = rm_cons_tty_close,
    + .write = rm_cons_tty_write,
    + .flush_chars = rm_cons_tty_flush_chars,
    + .write_room = rm_cons_mgr_tty_write_room,
    +};
    +
    +static int rm_cons_port_activate(struct tty_port *port, struct tty_struct *tty)
    +{
    + struct rm_cons_port *rm_port = container_of(port, struct rm_cons_port, port);
    +
    + return gh_rm_console_open(rm_port->vmid);
    +}
    +
    +static void rm_cons_port_shutdown(struct tty_port *port)
    +{
    + struct rm_cons_port *rm_port = container_of(port, struct rm_cons_port, port);
    + int ret;
    +
    + ret = gh_rm_console_close(rm_port->vmid);
    + if (ret)
    + dev_err(port->tty->dev, "Failed to close ttyGH%d: %d\n", rm_port->index, ret);
    +}
    +
    +static void rm_cons_port_destruct(struct tty_port *port)
    +{
    + struct rm_cons_port *rm_port = container_of(port, struct rm_cons_port, port);
    + struct rm_cons_drv_data *cons_data = dev_get_drvdata(port->tty->dev);
    +
    + spin_lock(&cons_data->ports_lock);
    + cons_data->ports[rm_port->index] = NULL;
    + spin_unlock(&cons_data->ports_lock);
    + kfree(rm_port);
    +}
    +
    +static const struct tty_port_operations rm_cons_port_ops = {
    + .activate = rm_cons_port_activate,
    + .shutdown = rm_cons_port_shutdown,
    + .destruct = rm_cons_port_destruct,
    +};
    +
    +static void rm_cons_console_flush_work(struct work_struct *ws)
    +{
    + struct rm_cons_drv_data *cons_data =
    + container_of(ws, struct rm_cons_drv_data, co_flush_work);
    + struct console *co = &cons_data->console;
    + struct rm_cons_port *rm_port = co->data;
    + unsigned long flags;
    + size_t size;
    + int ret, old_buf = cons_data->co_xmit_idx;
    +
    + spin_lock_irqsave(&cons_data->co_xmit_lock, flags);
    + cons_data->co_xmit_idx = 1 - old_buf;
    + size = cons_data->co_xmit_count;
    + cons_data->co_xmit_count = 0;
    + spin_unlock_irqrestore(&cons_data->co_xmit_lock, flags);
    +
    + do {
    + ret = gh_rm_console_write(rm_port->vmid, cons_data->co_xmit_buf[old_buf], size);
    + } while (ret && ret != -ENOMEM);
    +
    + gh_rm_console_flush(rm_port->vmid);
    +}
    +
    +static void rm_cons_console_write(struct console *co, const char *buf, unsigned count)
    +{
    + struct rm_cons_drv_data *cons_data = container_of(co, struct rm_cons_drv_data, console);
    + unsigned long flags;
    +
    + spin_lock_irqsave(&cons_data->co_xmit_lock, flags);
    + count = min(count, (unsigned)(PAGE_SIZE - cons_data->co_xmit_count));
    + memcpy(&cons_data->co_xmit_buf[cons_data->co_xmit_idx][cons_data->co_xmit_count], buf,
    + count);
    + cons_data->co_xmit_count += count;
    + spin_unlock_irqrestore(&cons_data->co_xmit_lock, flags);
    +
    + schedule_work(&cons_data->co_flush_work);
    +}
    +
    +static struct tty_driver *rm_cons_console_device(struct console *co, int *index)
    +{
    + struct rm_cons_drv_data *cons_data = container_of(co, struct rm_cons_drv_data, console);
    + struct rm_cons_port *rm_port = co->data;
    +
    + *index = rm_port->index;
    + return cons_data->tty_driver;
    +}
    +
    +static int rm_cons_console_setup(struct console *co, char *unused)
    +{
    + struct rm_cons_drv_data *cons_data = container_of(co, struct rm_cons_drv_data, console);
    + struct rm_cons_port *rm_port = co->data;
    + int ret;
    +
    + if (!tty_port_get(&rm_port->port))
    + return -ENODEV;
    +
    + cons_data->co_xmit_buf[0] = (unsigned char *)get_zeroed_page(GFP_KERNEL);
    + if (!cons_data->co_xmit_buf[0])
    + goto err;
    + cons_data->co_xmit_buf[1] = (unsigned char *)get_zeroed_page(GFP_KERNEL);
    + if (!cons_data->co_xmit_buf[1])
    + goto err;
    +
    + mutex_lock(&rm_port->port.mutex);
    + if (!tty_port_initialized(&rm_port->port)) {
    + ret = gh_rm_console_open(rm_port->vmid);
    + if (ret) {
    + dev_err(rm_port->port.tty->dev, "Failed to open %s%d: %d\n",
    + co->name, rm_port->index, ret);
    + goto err;
    + }
    + tty_port_set_initialized(&rm_port->port, true);
    + }
    + rm_port->port.console = true;
    + mutex_unlock(&rm_port->port.mutex);
    +
    + return 0;
    +err:
    + if (cons_data->co_xmit_buf[1])
    + free_page((unsigned long)cons_data->co_xmit_buf[1]);
    + if (cons_data->co_xmit_buf[0])
    + free_page((unsigned long)cons_data->co_xmit_buf[0]);
    + mutex_unlock(&rm_port->port.mutex);
    + tty_port_put(&rm_port->port);
    + return ret;
    +}
    +
    +static int rm_cons_console_exit(struct console *co)
    +{
    + struct rm_cons_port *rm_port = co->data;
    + int ret;
    +
    + mutex_lock(&rm_port->port.mutex);
    + rm_port->port.console = false;
    +
    + if (!tty_port_active(&rm_port->port)) {
    + ret = gh_rm_console_close(rm_port->vmid);
    + if (ret)
    + dev_err(rm_port->port.tty->dev, "Failed to close %s%d: %d\n",
    + co->name, rm_port->index, ret);
    + tty_port_set_initialized(&rm_port->port, false);
    + }
    +
    + mutex_unlock(&rm_port->port.mutex);
    + tty_port_put(&rm_port->port);
    +
    + return 0;
    +}
    +
    +static struct rm_cons_port *rm_cons_port_create(struct rm_cons_drv_data *cons_data, u16 vmid)
    +{
    + struct rm_cons_port *rm_port;
    + struct device *ttydev;
    + unsigned int index;
    + int ret;
    +
    + rm_port = kzalloc(sizeof(*rm_port), GFP_KERNEL);
    + if (!rm_port)
    + return ERR_PTR(-ENOMEM);
    + rm_port->vmid = vmid;
    + tty_port_init(&rm_port->port);
    + rm_port->port.ops = &rm_cons_port_ops;
    +
    + spin_lock(&cons_data->ports_lock);
    + for (index = 0; index < RM_CONS_TTY_ADAPATERS; index++) {
    + if (!cons_data->ports[index]) {
    + cons_data->ports[index] = rm_port;
    + rm_port->index = index;
    + break;
    + }
    + }
    + spin_unlock(&cons_data->ports_lock);
    + if (index >= RM_CONS_TTY_ADAPATERS) {
    + ret = -ENOSPC;
    + goto err_put_port;
    + }
    +
    + ttydev = tty_port_register_device_attr(&rm_port->port, cons_data->tty_driver, index,
    + cons_data->dev, rm_port, NULL);
    + if (IS_ERR(ttydev)) {
    + ret = PTR_ERR(ttydev);
    + goto err_put_port;
    + }
    +
    + return rm_port;
    +err_put_port:
    + tty_port_put(&rm_port->port);
    + return ERR_PTR(ret);
    +}
    +
    +static int rm_cons_console_probe(struct device *dev)
    +{
    + struct rm_cons_drv_data *cons_data;
    + struct rm_cons_port *rm_port;
    + int ret;
    + u16 vmid;
    +
    + cons_data = devm_kzalloc(dev, sizeof(*cons_data), GFP_KERNEL);
    + if (!cons_data)
    + return -ENOMEM;
    + dev_set_drvdata(dev, cons_data);
    + cons_data->dev = dev;
    +
    + cons_data->tty_driver = tty_alloc_driver(RM_CONS_TTY_ADAPATERS,
    + TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV |
    + TTY_DRIVER_RESET_TERMIOS);
    + if (IS_ERR(cons_data->tty_driver))
    + return PTR_ERR(cons_data->tty_driver);
    +
    + cons_data->tty_driver->driver_name = KBUILD_MODNAME;
    + cons_data->tty_driver->name = "ttyGH";
    + cons_data->tty_driver->type = TTY_DRIVER_TYPE_SYSTEM;
    + cons_data->tty_driver->subtype = SYSTEM_TYPE_TTY;
    + cons_data->tty_driver->init_termios = tty_std_termios;
    + tty_set_operations(cons_data->tty_driver, &rm_cons_tty_ops);
    +
    + ret = tty_register_driver(cons_data->tty_driver);
    + if (ret) {
    + dev_err(dev, "Could not register tty driver: %d\n", ret);
    + goto err_put_tty;
    + }
    +
    + spin_lock_init(&cons_data->ports_lock);
    +
    + cons_data->rm_cons_notif.notifier_call = rm_cons_notif_handler;
    + ret = gh_rm_register_notifier(&cons_data->rm_cons_notif);
    + if (ret) {
    + dev_err(dev, "Could not register for resource manager notifications: %d\n", ret);
    + goto err_put_tty;
    + }
    +
    + spin_lock_init(&cons_data->co_xmit_lock);
    + INIT_WORK(&cons_data->co_flush_work, rm_cons_console_flush_work);
    +
    + rm_port = rm_cons_port_create(cons_data, GH_VMID_SELF);
    + if (IS_ERR(rm_port)) {
    + ret = PTR_ERR(rm_port);
    + dev_err(dev, "Could not create own console: %d\n", ret);
    + goto err_unreg_notif;
    + }
    +
    + rm_port->port.console = 1;
    + strncpy(cons_data->console.name, "ttyGH", sizeof(cons_data->console.name));
    + cons_data->console.write = rm_cons_console_write;
    + cons_data->console.device = rm_cons_console_device;
    + cons_data->console.setup = rm_cons_console_setup;
    + cons_data->console.exit = rm_cons_console_exit;
    + cons_data->console.index = rm_port->index;
    + cons_data->console.data = rm_port;
    + register_console(&cons_data->console);
    +
    + ret = gh_rm_get_vmid(&vmid);
    + if (!ret) {
    + rm_port = rm_cons_port_create(cons_data, vmid);
    + if (IS_ERR(rm_port))
    + dev_warn(dev, "Could not create loopback console: %ld\n", PTR_ERR(rm_port));
    + } else {
    + dev_warn(dev, "Failed to get this VM's VMID: %d. Not creating loop-back console\n",
    + ret);
    + }
    +
    + return 0;
    +err_unreg_notif:
    + gh_rm_unregister_notifier(&cons_data->rm_cons_notif);
    +err_put_tty:
    + tty_driver_kref_put(cons_data->tty_driver);
    + return ret;
    +}
    +
    +static int rm_cons_console_remove(struct device *dev)
    +{
    + struct rm_cons_drv_data *cons_data = dev_get_drvdata(dev);
    +
    + unregister_console(&cons_data->console);
    + if (cons_data->co_xmit_buf[1])
    + free_page((unsigned long)cons_data->co_xmit_buf[1]);
    + if (cons_data->co_xmit_buf[0])
    + free_page((unsigned long)cons_data->co_xmit_buf[0]);
    + gh_rm_unregister_notifier(&cons_data->rm_cons_notif);
    + tty_unregister_driver(cons_data->tty_driver);
    + tty_driver_kref_put(cons_data->tty_driver);
    +
    + return 0;
    +}
    +
    +static struct gunyah_rm_cons_device_id rm_cons_console_ids[] = {
    + { .name = GH_RM_DEVICE_CONSOLE },
    + {}
    +};
    +MODULE_DEVICE_TABLE(gunyah_rsc_mgr, rm_cons_console_ids);
    +
    +static struct gh_rm_driver rm_cons_console_drv = {
    + .drv = {
    + .name = KBUILD_MODNAME,
    + .probe = rm_cons_console_probe,
    + .remove = rm_cons_console_remove,
    + },
    + .id_table = rm_cons_console_ids,
    +};
    +module_gh_rm_driver(rm_cons_console_drv);
    +
    +MODULE_LICENSE("GPL");
    +MODULE_DESCRIPTION("Gunyah Console");
    --
    2.25.1
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      Last update: 2022-10-11 02:12    [W:2.500 / U:0.056 seconds]
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