// SPDX-License-Identifier: GPL-2.0
/*
* LiteUART serial controller (LiteX) Driver
*
* Copyright (C) 2019-2020 Antmicro <www.antmicro.com>
*/
#include <linux/bits.h>
#include <linux/console.h>
#include <linux/interrupt.h>
#include <linux/litex.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/serial.h>
#include <linux/serial_core.h>
#include <linux/slab.h>
#include <linux/timer.h>
#include <linux/tty_flip.h>
#include <linux/xarray.h>
/*
* CSRs definitions (base address offsets + width)
*
* The definitions below are true for LiteX SoC configured for 8-bit CSR Bus,
* 32-bit aligned.
*
* Supporting other configurations might require new definitions or a more
* generic way of indexing the LiteX CSRs.
*
* For more details on how CSRs are defined and handled in LiteX, see comments
* in the LiteX SoC Driver: drivers/soc/litex/litex_soc_ctrl.c
*/
#define OFF_RXTX 0x00
#define OFF_TXFULL 0x04
#define OFF_RXEMPTY 0x08
#define OFF_EV_STATUS 0x0c
#define OFF_EV_PENDING 0x10
#define OFF_EV_ENABLE 0x14
/* events */
#define EV_TX BIT(0)
#define EV_RX BIT(1)
struct liteuart_port {
struct uart_port port;
struct timer_list timer;
u8 irq_reg;
};
#define to_liteuart_port(port) container_of(port, struct liteuart_port, port)
static DEFINE_XARRAY_FLAGS(liteuart_array, XA_FLAGS_ALLOC);
#ifdef CONFIG_SERIAL_LITEUART_CONSOLE
static struct console liteuart_console;
#endif
static struct uart_driver liteuart_driver = {
.owner = THIS_MODULE,
.driver_name = KBUILD_MODNAME,
.dev_name = "ttyLXU",
.major = 0,
.minor = 0,
.nr = CONFIG_SERIAL_LITEUART_MAX_PORTS,
#ifdef CONFIG_SERIAL_LITEUART_CONSOLE
.cons = &liteuart_console,
#endif
};
static void liteuart_update_irq_reg(struct uart_port *port, bool set, u8 mask)
{
struct liteuart_port *uart = to_liteuart_port(port);
if (set)
uart->irq_reg |= mask;
else
uart->irq_reg &= ~mask;
if (port->irq)
litex_write8(port->membase + OFF_EV_ENABLE, uart->irq_reg);
}
static void liteuart_stop_tx(struct uart_port *port)
{
liteuart_update_irq_reg(port, false, EV_TX);
}
static void liteuart_start_tx(struct uart_port *port)
{
liteuart_update_irq_reg(port, true, EV_TX);
}
static void liteuart_stop_rx(struct uart_port *port)
{
struct liteuart_port *uart = to_liteuart_port(port);
/* just delete timer */
del_timer(&uart->timer);
}
static void liteuart_rx_chars(struct uart_port *port)
{
unsigned char __iomem *membase = port->membase;
u8 ch;
while (!litex_read8(membase + OFF_RXEMPTY)) {
ch = litex_read8(membase + OFF_RXTX);
port->icount.rx++;
/* necessary for RXEMPTY to refresh its value */
litex_write8(membase + OFF_EV_PENDING, EV_RX);
/* no overflow bits in status */
if (!(uart_handle_sysrq_char(port, ch)))
uart_insert_char(port, 1, 0, ch, TTY_NORMAL);
}
tty_flip_buffer_push(&port->state->port);
}
static void liteuart_tx_chars(struct uart_port *port)
{
u8 ch;
uart_port_tx(port, ch,
!litex_read8(port->membase + OFF_TXFULL),
litex_write8(port->membase + OFF_RXTX, ch));
}
static irqreturn_t liteuart_interrupt(int irq, void *data)
{
struct liteuart_port *uart = data;
struct uart_port *port = &uart->port;
unsigned long flags;
u8 isr;
/*
* if polling, the context would be "in_serving_softirq", so use
* irq[save|restore] spin_lock variants to cover all possibilities
*/
uart_port_lock_irqsave(port, &flags);
isr = litex_read8(port->membase + OFF_EV_PENDING) & uart->irq_reg;
if (isr & EV_RX)
liteuart_rx_chars(port);
if (isr & EV_TX)
liteuart_tx_chars(port);
uart_port_unlock_irqrestore(port, flags);
return IRQ_RETVAL(isr);
}
static void liteuart_timer(struct timer_list *t)
{
struct liteuart_port *uart = from_timer(uart, t, timer);
struct uart_port *port = &uart->port;
liteuart_interrupt(0, port);
mod_timer(&uart->timer, jiffies + uart_poll_timeout(port));
}
static unsigned int liteuart_tx_empty(struct uart_port *port)
{
/* not really tx empty, just checking if tx is not full */
if (!litex_read8(port->membase + OFF_TXFULL))
return TIOCSER_TEMT;
return 0;
}
static void liteuart_set_mctrl(struct uart_port *port, unsigned int mctrl)
{
/* modem control register is not present in LiteUART */
}
static unsigned int liteuart_get_mctrl(struct uart_port *port)
{
return TIOCM_CTS | TIOCM_DSR | TIOCM_CAR;
}
static int liteuart_startup(struct uart_port *port)
{
struct liteuart_port *uart = to_liteuart_port(port);
unsigned long flags;
int ret;
if (port->irq) {
ret = request_irq(port->irq, liteuart_interrupt, 0,
KBUILD_MODNAME, uart);
if (ret) {
dev_warn(port->dev,
"line %d irq %d failed: switch to polling\n",
port->line, port->irq);
port->irq = 0;
}
}
uart_port_lock_irqsave(port, &flags);
/* only enabling rx irqs during startup */
liteuart_update_irq_reg(port, true, EV_RX);
uart_port_unlock_irqrestore(port, flags);
if (!port->irq) {
timer_setup(&uart->timer, liteuart_timer, 0);
mod_timer(&uart->timer, jiffies + uart_poll_timeout(port));
}
return 0;
}
static void liteuart_shutdown(struct uart_port *port)
{
struct liteuart_port *uart = to_liteuart_port(port);
unsigned long flags;
uart_port_lock_irqsave(port, &flags);
liteuart_update_irq_reg(port, false, EV_RX | EV_TX);
uart_port_unlock_irqrestore(port, flags);
if (port->irq)
free_irq(port->irq, port);
else
del_timer_sync(&uart->timer);
}
static void liteuart_set_termios(struct uart_port *port, struct ktermios *new,
const struct ktermios *old)
{
unsigned int baud;
unsigned long flags;
uart_port_lock_irqsave(port, &flags);
/* update baudrate */
baud = uart_get_baud_rate(port, new, old, 0, 460800);
uart_update_timeout(port, new->c_cflag, baud);
uart_port_unlock_irqrestore(port, flags);
}
static const char *liteuart_type(struct uart_port *port)
{
return "liteuart";
}
static void liteuart_config_port(struct uart_port *port, int flags)
{
/*
* Driver core for serial ports forces a non-zero value for port type.
* Write an arbitrary value here to accommodate the serial core driver,
* as ID part of UAPI is redundant.
*/
port->type = 1;
}
static int liteuart_verify_port(struct uart_port *port,
struct serial_struct *ser)
{
if (port->type != PORT_UNKNOWN && ser->type != 1)
return -EINVAL;
return 0;
}
static const struct uart_ops liteuart_ops = {
.tx_empty = liteuart_tx_empty,
.set_mctrl = liteuart_set_mctrl,
.get_mctrl = liteuart_get_mctrl,
.stop_tx = liteuart_stop_tx,
.start_tx = liteuart_start_tx,
.stop_rx = liteuart_stop_rx,
.startup = liteuart_startup,
.shutdown = liteuart_shutdown,
.set_termios = liteuart_set_termios,
.type = liteuart_type,
.config_port = liteuart_config_port,
.verify_port = liteuart_verify_port,
};
static int liteuart_probe(struct platform_device *pdev)
{
struct liteuart_port *uart;
struct uart_port *port;
struct xa_limit limit;
int dev_id, ret;
uart = devm_kzalloc(&pdev->dev, sizeof(struct liteuart_port), GFP_KERNEL);
if (!uart)
return -ENOMEM;
port = &uart->port;
/* get membase */
port->membase = devm_platform_get_and_ioremap_resource(pdev, 0, NULL);
if (IS_ERR(port->membase))
return PTR_ERR(port->membase);
ret = platform_get_irq_optional(pdev, 0);
if (ret < 0 && ret != -ENXIO)
return ret;
if (ret > 0)
port->irq = ret;
/* look for aliases; auto-enumerate for free index if not found */
dev_id = of_alias_get_id(pdev->dev.of_node, "serial");
if (dev_id < 0)
limit = XA_LIMIT(0, CONFIG_SERIAL_LITEUART_MAX_PORTS);
else
limit = XA_LIMIT(dev_id, dev_id);
ret = xa_alloc(&liteuart_array, &dev_id, uart, limit, GFP_KERNEL);
if (ret)
return ret;
/* values not from device tree */
port->dev = &pdev->dev;
port->iotype = UPIO_MEM;
port->flags = UPF_BOOT_AUTOCONF;
port->ops = &liteuart_ops;
port->fifosize = 16;
port->type = PORT_UNKNOWN;
port->line = dev_id;
spin_lock_init(&port->lock);
platform_set_drvdata(pdev, port);
ret = uart_add_one_port(&liteuart_driver, &uart->port);
if (ret)
goto err_erase_id;
return 0;
err_erase_id:
xa_erase(&liteuart_array, dev_id);
return ret;
}
static void liteuart_remove(struct platform_device *pdev)
{
struct uart_port *port = platform_get_drvdata(pdev);
unsigned int line = port->line;
uart_remove_one_port(&liteuart_driver, port);
xa_erase(&liteuart_array, line);
}
static const struct of_device_id liteuart_of_match[] = {
{ .compatible = "litex,liteuart" },
{}
};
MODULE_DEVICE_TABLE(of, liteuart_of_match);
static struct platform_driver liteuart_platform_driver = {
.probe = liteuart_probe,
.remove_new = liteuart_remove,
.driver = {
.name = KBUILD_MODNAME,
.of_match_table = liteuart_of_match,
},
};
#ifdef CONFIG_SERIAL_LITEUART_CONSOLE
static void liteuart_putchar(struct uart_port *port, unsigned char ch)
{
while (litex_read8(port->membase + OFF_TXFULL))
cpu_relax();
litex_write8(port->membase + OFF_RXTX, ch);
}
static void liteuart_console_write(struct console *co, const char *s,
unsigned int count)
{
struct liteuart_port *uart;
struct uart_port *port;
unsigned long flags;
uart = (struct liteuart_port *)xa_load(&liteuart_array, co->index);
port = &uart->port;
uart_port_lock_irqsave(port, &flags);
uart_console_write(port, s, count, liteuart_putchar);
uart_port_unlock_irqrestore(port, flags);
}
static int liteuart_console_setup(struct console *co, char *options)
{
struct liteuart_port *uart;
struct uart_port *port;
int baud = 115200;
int bits = 8;
int parity = 'n';
int flow = 'n';
uart = (struct liteuart_port *)xa_load(&liteuart_array, co->index);
if (!uart)
return -ENODEV;
port = &uart->port;
if (!port->membase)
return -ENODEV;
if (options)
uart_parse_options(options, &baud, &parity, &bits, &flow);
return uart_set_options(port, co, baud, parity, bits, flow);
}
static struct console liteuart_console = {
.name = KBUILD_MODNAME,
.write = liteuart_console_write,
.device = uart_console_device,
.setup = liteuart_console_setup,
.flags = CON_PRINTBUFFER,
.index = -1,
.data = &liteuart_driver,
};
static int __init liteuart_console_init(void)
{
register_console(&liteuart_console);
return 0;
}
console_initcall(liteuart_console_init);
static void early_liteuart_write(struct console *console, const char *s,
unsigned int count)
{
struct earlycon_device *device = console->data;
struct uart_port *port = &device->port;
uart_console_write(port, s, count, liteuart_putchar);
}
static int __init early_liteuart_setup(struct earlycon_device *device,
const char *options)
{
if (!device->port.membase)
return -ENODEV;
device->con->write = early_liteuart_write;
return 0;
}
OF_EARLYCON_DECLARE(liteuart, "litex,liteuart", early_liteuart_setup);
#endif /* CONFIG_SERIAL_LITEUART_CONSOLE */
static int __init liteuart_init(void)
{
int res;
res = uart_register_driver(&liteuart_driver);
if (res)
return res;
res = platform_driver_register(&liteuart_platform_driver);
if (res)
uart_unregister_driver(&liteuart_driver);
return res;
}
static void __exit liteuart_exit(void)
{
platform_driver_unregister(&liteuart_platform_driver);
uart_unregister_driver(&liteuart_driver);
}
module_init(liteuart_init);
module_exit(liteuart_exit);
MODULE_AUTHOR("Antmicro <www.antmicro.com>");
MODULE_DESCRIPTION("LiteUART serial driver");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:liteuart");
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