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// SPDX-License-Identifier: GPL-2.0+
/*
* Serial core port device driver
*
* Copyright (C) 2023 Texas Instruments Incorporated - https://www.ti.com/
* Author: Tony Lindgren <tony@atomide.com>
*/
#include <linux/device.h>
#include <linux/module.h>
#include <linux/pm_runtime.h>
#include <linux/serial_core.h>
#include <linux/spinlock.h>
#include "serial_base.h"
#define SERIAL_PORT_AUTOSUSPEND_DELAY_MS 500
/* Only considers pending TX for now. Caller must take care of locking */
static int __serial_port_busy(struct uart_port *port)
{
return !uart_tx_stopped(port) &&
uart_circ_chars_pending(&port->state->xmit);
}
static int serial_port_runtime_resume(struct device *dev)
{
struct serial_port_device *port_dev = to_serial_base_port_device(dev);
struct uart_port *port;
unsigned long flags;
port = port_dev->port;
if (port->flags & UPF_DEAD)
goto out;
/* Flush any pending TX for the port */
uart_port_lock_irqsave(port, &flags);
if (!port_dev->tx_enabled)
goto unlock;
if (__serial_port_busy(port))
port->ops->start_tx(port);
unlock:
uart_port_unlock_irqrestore(port, flags);
out:
pm_runtime_mark_last_busy(dev);
return 0;
}
static int serial_port_runtime_suspend(struct device *dev)
{
struct serial_port_device *port_dev = to_serial_base_port_device(dev);
struct uart_port *port = port_dev->port;
unsigned long flags;
bool busy;
if (port->flags & UPF_DEAD)
return 0;
uart_port_lock_irqsave(port, &flags);
if (!port_dev->tx_enabled) {
uart_port_unlock_irqrestore(port, flags);
return 0;
}
busy = __serial_port_busy(port);
if (busy)
port->ops->start_tx(port);
uart_port_unlock_irqrestore(port, flags);
if (busy)
pm_runtime_mark_last_busy(dev);
return busy ? -EBUSY : 0;
}
static void serial_base_port_set_tx(struct uart_port *port,
struct serial_port_device *port_dev,
bool enabled)
{
unsigned long flags;
uart_port_lock_irqsave(port, &flags);
port_dev->tx_enabled = enabled;
uart_port_unlock_irqrestore(port, flags);
}
void serial_base_port_startup(struct uart_port *port)
{
struct serial_port_device *port_dev = port->port_dev;
serial_base_port_set_tx(port, port_dev, true);
}
void serial_base_port_shutdown(struct uart_port *port)
{
struct serial_port_device *port_dev = port->port_dev;
serial_base_port_set_tx(port, port_dev, false);
}
static DEFINE_RUNTIME_DEV_PM_OPS(serial_port_pm,
serial_port_runtime_suspend,
serial_port_runtime_resume, NULL);
static int serial_port_probe(struct device *dev)
{
pm_runtime_enable(dev);
pm_runtime_set_autosuspend_delay(dev, SERIAL_PORT_AUTOSUSPEND_DELAY_MS);
pm_runtime_use_autosuspend(dev);
return 0;
}
static int serial_port_remove(struct device *dev)
{
pm_runtime_dont_use_autosuspend(dev);
pm_runtime_disable(dev);
return 0;
}
/*
* Serial core port device init functions. Note that the physical serial
* port device driver may not have completed probe at this point.
*/
int uart_add_one_port(struct uart_driver *drv, struct uart_port *port)
{
return serial_ctrl_register_port(drv, port);
}
EXPORT_SYMBOL(uart_add_one_port);
void uart_remove_one_port(struct uart_driver *drv, struct uart_port *port)
{
serial_ctrl_unregister_port(drv, port);
}
EXPORT_SYMBOL(uart_remove_one_port);
static struct device_driver serial_port_driver = {
.name = "port",
.suppress_bind_attrs = true,
.probe = serial_port_probe,
.remove = serial_port_remove,
.pm = pm_ptr(&serial_port_pm),
};
int serial_base_port_init(void)
{
return serial_base_driver_register(&serial_port_driver);
}
void serial_base_port_exit(void)
{
serial_base_driver_unregister(&serial_port_driver);
}
MODULE_AUTHOR("Tony Lindgren <tony@atomide.com>");
MODULE_DESCRIPTION("Serial controller port driver");
MODULE_LICENSE("GPL");
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