// SPDX-License-Identifier: GPL-2.0+
/*
* Serial core port device driver
*
* Copyright (C) 2023 Texas Instruments Incorporated - https://www.ti.com/
* Author: Tony Lindgren <[email protected]>
*/
#include <linux/device.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
#include <linux/pnp.h>
#include <linux/property.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) &&
!kfifo_is_empty(&port->state->port.xmit_fifo);
}
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;
/*
* Nothing to do on pm_runtime_force_suspend(), see
* DEFINE_RUNTIME_DEV_PM_OPS.
*/
if (!pm_runtime_enabled(dev))
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);
/**
* __uart_read_properties - read firmware properties of the given UART port
* @port: corresponding port
* @use_defaults: apply defaults (when %true) or validate the values (when %false)
*
* The following device properties are supported:
* - clock-frequency (optional)
* - fifo-size (optional)
* - no-loopback-test (optional)
* - reg-shift (defaults may apply)
* - reg-offset (value may be validated)
* - reg-io-width (defaults may apply or value may be validated)
* - interrupts (OF only)
* - serial [alias ID] (OF only)
*
* If the port->dev is of struct platform_device type the interrupt line
* will be retrieved via platform_get_irq() call against that device.
* Otherwise it will be assigned by fwnode_irq_get() call. In both cases
* the index 0 of the resource is used.
*
* The caller is responsible to initialize the following fields of the @port
* ->dev (must be valid)
* ->flags
* ->mapbase
* ->mapsize
* ->regshift (if @use_defaults is false)
* before calling this function. Alternatively the above mentioned fields
* may be zeroed, in such case the only ones, that have associated properties
* found, will be set to the respective values.
*
* If no error happened, the ->irq, ->mapbase, ->mapsize will be altered.
* The ->iotype is always altered.
*
* When @use_defaults is true and the respective property is not found
* the following values will be applied:
* ->regshift = 0
* In this case IRQ must be provided, otherwise an error will be returned.
*
* When @use_defaults is false and the respective property is found
* the following values will be validated:
* - reg-io-width (->iotype)
* - reg-offset (->mapsize against ->mapbase)
*
* Returns: 0 on success or negative errno on failure
*/
static int __uart_read_properties(struct uart_port *port, bool use_defaults)
{
struct device *dev = port->dev;
u32 value;
int ret;
/* Read optional UART functional clock frequency */
device_property_read_u32(dev, "clock-frequency", &port->uartclk);
/* Read the registers alignment (default: 8-bit) */
ret = device_property_read_u32(dev, "reg-shift", &value);
if (ret)
port->regshift = use_defaults ? 0 : port->regshift;
else
port->regshift = value;
/* Read the registers I/O access type (default: MMIO 8-bit) */
ret = device_property_read_u32(dev, "reg-io-width", &value);
if (ret) {
port->iotype = UPIO_MEM;
} else {
switch (value) {
case 1:
port->iotype = UPIO_MEM;
break;
case 2:
port->iotype = UPIO_MEM16;
break;
case 4:
port->iotype = device_is_big_endian(dev) ? UPIO_MEM32BE : UPIO_MEM32;
break;
default:
if (!use_defaults) {
dev_err(dev, "Unsupported reg-io-width (%u)\n", value);
return -EINVAL;
}
port->iotype = UPIO_UNKNOWN;
break;
}
}
/* Read the address mapping base offset (default: no offset) */
ret = device_property_read_u32(dev, "reg-offset", &value);
if (ret)
value = 0;
/* Check for shifted address mapping overflow */
if (!use_defaults && port->mapsize < value) {
dev_err(dev, "reg-offset %u exceeds region size %pa\n", value, &port->mapsize);
return -EINVAL;
}
port->mapbase += value;
port->mapsize -= value;
/* Read optional FIFO size */
device_property_read_u32(dev, "fifo-size", &port->fifosize);
if (device_property_read_bool(dev, "no-loopback-test"))
port->flags |= UPF_SKIP_TEST;
/* Get index of serial line, if found in DT aliases */
ret = of_alias_get_id(dev_of_node(dev), "serial");
if (ret >= 0)
port->line = ret;
if (dev_is_platform(dev))
ret = platform_get_irq(to_platform_device(dev), 0);
else if (dev_is_pnp(dev)) {
ret = pnp_irq(to_pnp_dev(dev), 0);
if (ret < 0)
ret = -ENXIO;
} else
ret = fwnode_irq_get(dev_fwnode(dev), 0);
if (ret == -EPROBE_DEFER)
return ret;
if (ret > 0)
port->irq = ret;
else if (use_defaults)
/* By default IRQ support is mandatory */
return ret;
else
port->irq = 0;
port->flags |= UPF_SHARE_IRQ;
return 0;
}
int uart_read_port_properties(struct uart_port *port)
{
return __uart_read_properties(port, true);
}
EXPORT_SYMBOL_GPL(uart_read_port_properties);
int uart_read_and_validate_port_properties(struct uart_port *port)
{
return __uart_read_properties(port, false);
}
EXPORT_SYMBOL_GPL(uart_read_and_validate_port_properties);
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 <[email protected]>");
MODULE_DESCRIPTION("Serial controller port driver");
MODULE_LICENSE("GPL");
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