linux/drivers/tty/serial/netx-serial.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (c) 2005 Sascha Hauer <s.hauer@pengutronix.de>, Pengutronix
 */

#if defined(CONFIG_SERIAL_NETX_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
#define SUPPORT_SYSRQ
#endif

#include <linux/device.h>
#include <linux/module.h>
#include <linux/ioport.h>
#include <linux/init.h>
#include <linux/console.h>
#include <linux/sysrq.h>
#include <linux/platform_device.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/serial_core.h>
#include <linux/serial.h>

#include <asm/io.h>
#include <asm/irq.h>
#include <mach/hardware.h>
#include <mach/netx-regs.h>

/* We've been assigned a range on the "Low-density serial ports" major */
#define SERIAL_NX_MAJOR	204
#define MINOR_START	170

enum uart_regs {
	UART_DR              = 0x00,
	UART_SR              = 0x04,
	UART_LINE_CR         = 0x08,
	UART_BAUDDIV_MSB     = 0x0c,
	UART_BAUDDIV_LSB     = 0x10,
	UART_CR              = 0x14,
	UART_FR              = 0x18,
	UART_IIR             = 0x1c,
	UART_ILPR            = 0x20,
	UART_RTS_CR          = 0x24,
	UART_RTS_LEAD        = 0x28,
	UART_RTS_TRAIL       = 0x2c,
	UART_DRV_ENABLE      = 0x30,
	UART_BRM_CR          = 0x34,
	UART_RXFIFO_IRQLEVEL = 0x38,
	UART_TXFIFO_IRQLEVEL = 0x3c,
};

#define SR_FE (1<<0)
#define SR_PE (1<<1)
#define SR_BE (1<<2)
#define SR_OE (1<<3)

#define LINE_CR_BRK       (1<<0)
#define LINE_CR_PEN       (1<<1)
#define LINE_CR_EPS       (1<<2)
#define LINE_CR_STP2      (1<<3)
#define LINE_CR_FEN       (1<<4)
#define LINE_CR_5BIT      (0<<5)
#define LINE_CR_6BIT      (1<<5)
#define LINE_CR_7BIT      (2<<5)
#define LINE_CR_8BIT      (3<<5)
#define LINE_CR_BITS_MASK (3<<5)

#define CR_UART_EN (1<<0)
#define CR_SIREN   (1<<1)
#define CR_SIRLP   (1<<2)
#define CR_MSIE    (1<<3)
#define CR_RIE     (1<<4)
#define CR_TIE     (1<<5)
#define CR_RTIE    (1<<6)
#define CR_LBE     (1<<7)

#define FR_CTS  (1<<0)
#define FR_DSR  (1<<1)
#define FR_DCD  (1<<2)
#define FR_BUSY (1<<3)
#define FR_RXFE (1<<4)
#define FR_TXFF (1<<5)
#define FR_RXFF (1<<6)
#define FR_TXFE (1<<7)

#define IIR_MIS (1<<0)
#define IIR_RIS (1<<1)
#define IIR_TIS (1<<2)
#define IIR_RTIS (1<<3)
#define IIR_MASK 0xf

#define RTS_CR_AUTO (1<<0)
#define RTS_CR_RTS  (1<<1)
#define RTS_CR_COUNT (1<<2)
#define RTS_CR_MOD2  (1<<3)
#define RTS_CR_RTS_POL (1<<4)
#define RTS_CR_CTS_CTR (1<<5)
#define RTS_CR_CTS_POL (1<<6)
#define RTS_CR_STICK   (1<<7)

#define UART_PORT_SIZE 0x40
#define DRIVER_NAME "netx-uart"

struct netx_port {
	struct uart_port	port;
};

static void netx_stop_tx(struct uart_port *port)
{
	unsigned int val;
	val = readl(port->membase + UART_CR);
	writel(val & ~CR_TIE,  port->membase + UART_CR);
}

static void netx_stop_rx(struct uart_port *port)
{
	unsigned int val;
	val = readl(port->membase + UART_CR);
	writel(val & ~CR_RIE,  port->membase + UART_CR);
}

static void netx_enable_ms(struct uart_port *port)
{
	unsigned int val;
	val = readl(port->membase + UART_CR);
	writel(val | CR_MSIE, port->membase + UART_CR);
}

static inline void netx_transmit_buffer(struct uart_port *port)
{
	struct circ_buf *xmit = &port->state->xmit;

	if (port->x_char) {
		writel(port->x_char, port->membase + UART_DR);
		port->icount.tx++;
		port->x_char = 0;
		return;
	}

	if (uart_tx_stopped(port) || uart_circ_empty(xmit)) {
		netx_stop_tx(port);
		return;
	}

	do {
		/* send xmit->buf[xmit->tail]
		 * out the port here */
		writel(xmit->buf[xmit->tail], port->membase + UART_DR);
		xmit->tail = (xmit->tail + 1) &
		         (UART_XMIT_SIZE - 1);
		port->icount.tx++;
		if (uart_circ_empty(xmit))
			break;
	} while (!(readl(port->membase + UART_FR) & FR_TXFF));

	if (uart_circ_empty(xmit))
		netx_stop_tx(port);
}

static void netx_start_tx(struct uart_port *port)
{
	writel(
	    readl(port->membase + UART_CR) | CR_TIE, port->membase + UART_CR);

	if (!(readl(port->membase + UART_FR) & FR_TXFF))
		netx_transmit_buffer(port);
}

static unsigned int netx_tx_empty(struct uart_port *port)
{
	return readl(port->membase + UART_FR) & FR_BUSY ? 0 : TIOCSER_TEMT;
}

static void netx_txint(struct uart_port *port)
{
	struct circ_buf *xmit = &port->state->xmit;

	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
		netx_stop_tx(port);
		return;
	}

	netx_transmit_buffer(port);

	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
		uart_write_wakeup(port);
}

static void netx_rxint(struct uart_port *port, unsigned long *flags)
{
	unsigned char rx, flg, status;

	while (!(readl(port->membase + UART_FR) & FR_RXFE)) {
		rx = readl(port->membase + UART_DR);
		flg = TTY_NORMAL;
		port->icount.rx++;
		status = readl(port->membase + UART_SR);
		if (status & SR_BE) {
			writel(0, port->membase + UART_SR);
			if (uart_handle_break(port))
				continue;
		}

		if (unlikely(status & (SR_FE | SR_PE | SR_OE))) {

			if (status & SR_PE)
				port->icount.parity++;
			else if (status & SR_FE)
				port->icount.frame++;
			if (status & SR_OE)
				port->icount.overrun++;

			status &= port->read_status_mask;

			if (status & SR_BE)
				flg = TTY_BREAK;
			else if (status & SR_PE)
				flg = TTY_PARITY;
			else if (status & SR_FE)
				flg = TTY_FRAME;
		}

		if (uart_handle_sysrq_char(port, rx))
			continue;

		uart_insert_char(port, status, SR_OE, rx, flg);
	}

	spin_unlock_irqrestore(&port->lock, *flags);
	tty_flip_buffer_push(&port->state->port);
	spin_lock_irqsave(&port->lock, *flags);
}

static irqreturn_t netx_int(int irq, void *dev_id)
{
	struct uart_port *port = dev_id;
	unsigned long flags;
	unsigned char status;

	spin_lock_irqsave(&port->lock,flags);

	status = readl(port->membase + UART_IIR) & IIR_MASK;
	while (status) {
		if (status & IIR_RIS)
			netx_rxint(port, &flags);
		if (status & IIR_TIS)
			netx_txint(port);
		if (status & IIR_MIS) {
			if (readl(port->membase + UART_FR) & FR_CTS)
				uart_handle_cts_change(port, 1);
			else
				uart_handle_cts_change(port, 0);
		}
		writel(0, port->membase + UART_IIR);
		status = readl(port->membase + UART_IIR) & IIR_MASK;
	}

	spin_unlock_irqrestore(&port->lock,flags);
	return IRQ_HANDLED;
}

static unsigned int netx_get_mctrl(struct uart_port *port)
{
	unsigned int ret = TIOCM_DSR | TIOCM_CAR;

	if (readl(port->membase + UART_FR) & FR_CTS)
		ret |= TIOCM_CTS;

	return ret;
}

static void netx_set_mctrl(struct uart_port *port, unsigned int mctrl)
{
	unsigned int val;

	/* FIXME: Locking needed ? */
	if (mctrl & TIOCM_RTS) {
		val = readl(port->membase + UART_RTS_CR);
		writel(val | RTS_CR_RTS, port->membase + UART_RTS_CR);
	}
}

static void netx_break_ctl(struct uart_port *port, int break_state)
{
	unsigned int line_cr;
	spin_lock_irq(&port->lock);

	line_cr = readl(port->membase + UART_LINE_CR);
	if (break_state != 0)
		line_cr |= LINE_CR_BRK;
	else
		line_cr &= ~LINE_CR_BRK;
	writel(line_cr, port->membase + UART_LINE_CR);

	spin_unlock_irq(&port->lock);
}

static int netx_startup(struct uart_port *port)
{
	int ret;

	ret = request_irq(port->irq, netx_int, 0,
			     DRIVER_NAME, port);
	if (ret) {
		dev_err(port->dev, "unable to grab irq%d\n",port->irq);
		goto exit;
	}

	writel(readl(port->membase + UART_LINE_CR) | LINE_CR_FEN,
		port->membase + UART_LINE_CR);

	writel(CR_MSIE | CR_RIE | CR_TIE | CR_RTIE | CR_UART_EN,
		port->membase + UART_CR);

exit:
	return ret;
}

static void netx_shutdown(struct uart_port *port)
{
	writel(0, port->membase + UART_CR) ;

	free_irq(port->irq, port);
}

static void
netx_set_termios(struct uart_port *port, struct ktermios *termios,
		   struct ktermios *old)
{
	unsigned int baud, quot;
	unsigned char old_cr;
	unsigned char line_cr = LINE_CR_FEN;
	unsigned char rts_cr = 0;

	switch (termios->c_cflag & CSIZE) {
	case CS5:
		line_cr |= LINE_CR_5BIT;
		break;
	case CS6:
		line_cr |= LINE_CR_6BIT;
		break;
	case CS7:
		line_cr |= LINE_CR_7BIT;
		break;
	case CS8:
		line_cr |= LINE_CR_8BIT;
		break;
	}

	if (termios->c_cflag & CSTOPB)
		line_cr |= LINE_CR_STP2;

	if (termios->c_cflag & PARENB) {
		line_cr |= LINE_CR_PEN;
		if (!(termios->c_cflag & PARODD))
			line_cr |= LINE_CR_EPS;
	}

	if (termios->c_cflag & CRTSCTS)
		rts_cr = RTS_CR_AUTO | RTS_CR_CTS_CTR | RTS_CR_RTS_POL;

	baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk/16);
	quot = baud * 4096;
	quot /= 1000;
	quot *= 256;
	quot /= 100000;

	spin_lock_irq(&port->lock);

	uart_update_timeout(port, termios->c_cflag, baud);

	old_cr = readl(port->membase + UART_CR);

	/* disable interrupts */
	writel(old_cr & ~(CR_MSIE | CR_RIE | CR_TIE | CR_RTIE),
		port->membase + UART_CR);

	/* drain transmitter */
	while (readl(port->membase + UART_FR) & FR_BUSY);

	/* disable UART */
	writel(old_cr & ~CR_UART_EN, port->membase + UART_CR);

	/* modem status interrupts */
	old_cr &= ~CR_MSIE;
	if (UART_ENABLE_MS(port, termios->c_cflag))
		old_cr |= CR_MSIE;

	writel((quot>>8) & 0xff, port->membase + UART_BAUDDIV_MSB);
	writel(quot & 0xff, port->membase + UART_BAUDDIV_LSB);
	writel(line_cr, port->membase + UART_LINE_CR);

	writel(rts_cr, port->membase + UART_RTS_CR);

	/*
	 * Characters to ignore
	 */
	port->ignore_status_mask = 0;
	if (termios->c_iflag & IGNPAR)
		port->ignore_status_mask |= SR_PE;
	if (termios->c_iflag & IGNBRK) {
		port->ignore_status_mask |= SR_BE;
		/*
		 * If we're ignoring parity and break indicators,
		 * ignore overruns too (for real raw support).
		 */
		if (termios->c_iflag & IGNPAR)
			port->ignore_status_mask |= SR_PE;
	}

	port->read_status_mask = 0;
	if (termios->c_iflag & (IGNBRK | BRKINT | PARMRK))
		port->read_status_mask |= SR_BE;
	if (termios->c_iflag & INPCK)
		port->read_status_mask |= SR_PE | SR_FE;

	writel(old_cr, port->membase + UART_CR);

	spin_unlock_irq(&port->lock);
}

static const char *netx_type(struct uart_port *port)
{
	return port->type == PORT_NETX ? "NETX" : NULL;
}

static void netx_release_port(struct uart_port *port)
{
	release_mem_region(port->mapbase, UART_PORT_SIZE);
}

static int netx_request_port(struct uart_port *port)
{
	return request_mem_region(port->mapbase, UART_PORT_SIZE,
			DRIVER_NAME) != NULL ? 0 : -EBUSY;
}

static void netx_config_port(struct uart_port *port, int flags)
{
	if (flags & UART_CONFIG_TYPE && netx_request_port(port) == 0)
		port->type = PORT_NETX;
}

static int
netx_verify_port(struct uart_port *port, struct serial_struct *ser)
{
	int ret = 0;

	if (ser->type != PORT_UNKNOWN && ser->type != PORT_NETX)
		ret = -EINVAL;

	return ret;
}

static struct uart_ops netx_pops = {
	.tx_empty	= netx_tx_empty,
	.set_mctrl	= netx_set_mctrl,
	.get_mctrl	= netx_get_mctrl,
	.stop_tx	= netx_stop_tx,
	.start_tx	= netx_start_tx,
	.stop_rx	= netx_stop_rx,
	.enable_ms	= netx_enable_ms,
	.break_ctl	= netx_break_ctl,
	.startup	= netx_startup,
	.shutdown	= netx_shutdown,
	.set_termios	= netx_set_termios,
	.type		= netx_type,
	.release_port	= netx_release_port,
	.request_port	= netx_request_port,
	.config_port	= netx_config_port,
	.verify_port	= netx_verify_port,
};

static struct netx_port netx_ports[] = {
	{
	.port = {
		.type = PORT_NETX,
		.iotype = UPIO_MEM,
		.membase = (char __iomem *)io_p2v(NETX_PA_UART0),
		.mapbase = NETX_PA_UART0,
		.irq = NETX_IRQ_UART0,
		.uartclk = 100000000,
		.fifosize = 16,
		.flags = UPF_BOOT_AUTOCONF,
		.ops = &netx_pops,
		.line = 0,
	},
	}, {
	.port = {
		.type = PORT_NETX,
		.iotype = UPIO_MEM,
		.membase = (char __iomem *)io_p2v(NETX_PA_UART1),
		.mapbase = NETX_PA_UART1,
		.irq = NETX_IRQ_UART1,
		.uartclk = 100000000,
		.fifosize = 16,
		.flags = UPF_BOOT_AUTOCONF,
		.ops = &netx_pops,
		.line = 1,
	},
	}, {
	.port = {
		.type = PORT_NETX,
		.iotype = UPIO_MEM,
		.membase = (char __iomem *)io_p2v(NETX_PA_UART2),
		.mapbase = NETX_PA_UART2,
		.irq = NETX_IRQ_UART2,
		.uartclk = 100000000,
		.fifosize = 16,
		.flags = UPF_BOOT_AUTOCONF,
		.ops = &netx_pops,
		.line = 2,
	},
	}
};

#ifdef CONFIG_SERIAL_NETX_CONSOLE

static void netx_console_putchar(struct uart_port *port, int ch)
{
	while (readl(port->membase + UART_FR) & FR_BUSY);
	writel(ch, port->membase + UART_DR);
}

static void
netx_console_write(struct console *co, const char *s, unsigned int count)
{
	struct uart_port *port = &netx_ports[co->index].port;
	unsigned char cr_save;

	cr_save = readl(port->membase + UART_CR);
	writel(cr_save | CR_UART_EN, port->membase + UART_CR);

	uart_console_write(port, s, count, netx_console_putchar);

	while (readl(port->membase + UART_FR) & FR_BUSY);
	writel(cr_save, port->membase + UART_CR);
}

static void __init
netx_console_get_options(struct uart_port *port, int *baud,
			int *parity, int *bits, int *flow)
{
	unsigned char line_cr;

	*baud = (readl(port->membase + UART_BAUDDIV_MSB) << 8) |
		readl(port->membase + UART_BAUDDIV_LSB);
	*baud *= 1000;
	*baud /= 4096;
	*baud *= 1000;
	*baud /= 256;
	*baud *= 100;

	line_cr = readl(port->membase + UART_LINE_CR);
	*parity = 'n';
	if (line_cr & LINE_CR_PEN) {
		if (line_cr & LINE_CR_EPS)
			*parity = 'e';
		else
			*parity = 'o';
	}

	switch (line_cr & LINE_CR_BITS_MASK) {
	case LINE_CR_8BIT:
		*bits = 8;
		break;
	case LINE_CR_7BIT:
		*bits = 7;
		break;
	case LINE_CR_6BIT:
		*bits = 6;
		break;
	case LINE_CR_5BIT:
		*bits = 5;
		break;
	}

	if (readl(port->membase + UART_RTS_CR) & RTS_CR_AUTO)
		*flow = 'r';
}

static int __init
netx_console_setup(struct console *co, char *options)
{
	struct netx_port *sport;
	int baud = 9600;
	int bits = 8;
	int parity = 'n';
	int flow = 'n';

	/*
	 * Check whether an invalid uart number has been specified, and
	 * if so, search for the first available port that does have
	 * console support.
	 */
	if (co->index == -1 || co->index >= ARRAY_SIZE(netx_ports))
		co->index = 0;
	sport = &netx_ports[co->index];

	if (options) {
		uart_parse_options(options, &baud, &parity, &bits, &flow);
	} else {
		/* if the UART is enabled, assume it has been correctly setup
		 * by the bootloader and get the options
		 */
		if (readl(sport->port.membase + UART_CR) & CR_UART_EN) {
			netx_console_get_options(&sport->port, &baud,
			&parity, &bits, &flow);
		}

	}

	return uart_set_options(&sport->port, co, baud, parity, bits, flow);
}

static struct uart_driver netx_reg;
static struct console netx_console = {
	.name		= "ttyNX",
	.write		= netx_console_write,
	.device		= uart_console_device,
	.setup		= netx_console_setup,
	.flags		= CON_PRINTBUFFER,
	.index		= -1,
	.data		= &netx_reg,
};

static int __init netx_console_init(void)
{
	register_console(&netx_console);
	return 0;
}
console_initcall(netx_console_init);

#define NETX_CONSOLE	&netx_console
#else
#define NETX_CONSOLE	NULL
#endif

static struct uart_driver netx_reg = {
	.owner          = THIS_MODULE,
	.driver_name    = DRIVER_NAME,
	.dev_name       = "ttyNX",
	.major          = SERIAL_NX_MAJOR,
	.minor          = MINOR_START,
	.nr             = ARRAY_SIZE(netx_ports),
	.cons           = NETX_CONSOLE,
};

static int serial_netx_suspend(struct platform_device *pdev, pm_message_t state)
{
	struct netx_port *sport = platform_get_drvdata(pdev);

	if (sport)
		uart_suspend_port(&netx_reg, &sport->port);

	return 0;
}

static int serial_netx_resume(struct platform_device *pdev)
{
	struct netx_port *sport = platform_get_drvdata(pdev);

	if (sport)
		uart_resume_port(&netx_reg, &sport->port);

	return 0;
}

static int serial_netx_probe(struct platform_device *pdev)
{
	struct uart_port *port = &netx_ports[pdev->id].port;

	dev_info(&pdev->dev, "initialising\n");

	port->dev = &pdev->dev;

	writel(1, port->membase + UART_RXFIFO_IRQLEVEL);
	uart_add_one_port(&netx_reg, &netx_ports[pdev->id].port);
	platform_set_drvdata(pdev, &netx_ports[pdev->id]);

	return 0;
}

static int serial_netx_remove(struct platform_device *pdev)
{
	struct netx_port *sport = platform_get_drvdata(pdev);

	if (sport)
		uart_remove_one_port(&netx_reg, &sport->port);

	return 0;
}

static struct platform_driver serial_netx_driver = {
	.probe          = serial_netx_probe,
	.remove         = serial_netx_remove,

	.suspend	= serial_netx_suspend,
	.resume		= serial_netx_resume,

	.driver		= {
		.name   = DRIVER_NAME,
	},
};

static int __init netx_serial_init(void)
{
	int ret;

	printk(KERN_INFO "Serial: NetX driver\n");

	ret = uart_register_driver(&netx_reg);
	if (ret)
		return ret;

	ret = platform_driver_register(&serial_netx_driver);
	if (ret != 0)
		uart_unregister_driver(&netx_reg);

	return 0;
}

static void __exit netx_serial_exit(void)
{
	platform_driver_unregister(&serial_netx_driver);
	uart_unregister_driver(&netx_reg);
}

module_init(netx_serial_init);
module_exit(netx_serial_exit);

MODULE_AUTHOR("Sascha Hauer");
MODULE_DESCRIPTION("NetX serial port driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:" DRIVER_NAME);