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// SPDX-License-Identifier: GPL-2.0/* * MPS2 UART driver * * Copyright (C) 2015 ARM Limited * * Author: Vladimir Murzin <vladimir.murzin@arm.com> * * TODO: support for SysRq */ #define pr_fmt(fmt)	KBUILD_MODNAME ": " fmt #include <linux/bitops.h>#include <linux/clk.h>#include <linux/console.h>#include <linux/io.h>#include <linux/kernel.h>#include <linux/of.h>#include <linux/platform_device.h>#include <linux/serial_core.h>#include <linux/tty_flip.h>#include <linux/types.h>#include <linux/idr.h> #define SERIAL_NAME	"ttyMPS"#define DRIVER_NAME	"mps2-uart"#define MAKE_NAME(x)	(DRIVER_NAME # x) #define UARTn_DATA				0x00 #define UARTn_STATE				0x04#define UARTn_STATE_TX_FULL			BIT(0)#define UARTn_STATE_RX_FULL			BIT(1)#define UARTn_STATE_TX_OVERRUN			BIT(2)#define UARTn_STATE_RX_OVERRUN			BIT(3) #define UARTn_CTRL				0x08#define UARTn_CTRL_TX_ENABLE			BIT(0)#define UARTn_CTRL_RX_ENABLE			BIT(1)#define UARTn_CTRL_TX_INT_ENABLE		BIT(2)#define UARTn_CTRL_RX_INT_ENABLE		BIT(3)#define UARTn_CTRL_TX_OVERRUN_INT_ENABLE	BIT(4)#define UARTn_CTRL_RX_OVERRUN_INT_ENABLE	BIT(5) #define UARTn_INT				0x0c#define UARTn_INT_TX				BIT(0)#define UARTn_INT_RX				BIT(1)#define UARTn_INT_TX_OVERRUN			BIT(2)#define UARTn_INT_RX_OVERRUN			BIT(3) #define UARTn_BAUDDIV				0x10#define UARTn_BAUDDIV_MASK			GENMASK(20, 0) /* * Helpers to make typical enable/disable operations more readable. */#define UARTn_CTRL_TX_GRP	(UARTn_CTRL_TX_ENABLE		 |\				 UARTn_CTRL_TX_INT_ENABLE	 |\				 UARTn_CTRL_TX_OVERRUN_INT_ENABLE) #define UARTn_CTRL_RX_GRP	(UARTn_CTRL_RX_ENABLE		 |\				 UARTn_CTRL_RX_INT_ENABLE	 |\				 UARTn_CTRL_RX_OVERRUN_INT_ENABLE) #define MPS2_MAX_PORTS		3 #define UART_PORT_COMBINED_IRQ	BIT(0) struct mps2_uart_port {	struct uart_port port;	struct clk *clk;	unsigned int tx_irq;	unsigned int rx_irq;	unsigned int flags;}; static inline struct mps2_uart_port *to_mps2_port(struct uart_port *port){	return container_of(port, struct mps2_uart_port, port);} static void mps2_uart_write8(struct uart_port *port, u8 val, unsigned int off){	struct mps2_uart_port *mps_port = to_mps2_port(port); 	writeb(val, mps_port->port.membase + off);} static u8 mps2_uart_read8(struct uart_port *port, unsigned int off){	struct mps2_uart_port *mps_port = to_mps2_port(port); 	return readb(mps_port->port.membase + off);} static void mps2_uart_write32(struct uart_port *port, u32 val, unsigned int off){	struct mps2_uart_port *mps_port = to_mps2_port(port); 	writel_relaxed(val, mps_port->port.membase + off);} static unsigned int mps2_uart_tx_empty(struct uart_port *port){	u8 status = mps2_uart_read8(port, UARTn_STATE); 	return (status & UARTn_STATE_TX_FULL) ? 0 : TIOCSER_TEMT;} static void mps2_uart_set_mctrl(struct uart_port *port, unsigned int mctrl){} static unsigned int mps2_uart_get_mctrl(struct uart_port *port){	return TIOCM_CAR | TIOCM_CTS | TIOCM_DSR;} static void mps2_uart_stop_tx(struct uart_port *port){	u8 control = mps2_uart_read8(port, UARTn_CTRL); 	control &= ~UARTn_CTRL_TX_INT_ENABLE; 	mps2_uart_write8(port, control, UARTn_CTRL);} static void mps2_uart_tx_chars(struct uart_port *port){	u8 ch; 	uart_port_tx(port, ch,		mps2_uart_tx_empty(port),		mps2_uart_write8(port, ch, UARTn_DATA));} static void mps2_uart_start_tx(struct uart_port *port){	u8 control = mps2_uart_read8(port, UARTn_CTRL); 	control |= UARTn_CTRL_TX_INT_ENABLE; 	mps2_uart_write8(port, control, UARTn_CTRL); 	/*	 * We've just unmasked the TX IRQ and now slow-starting via	 * polling; if there is enough data to fill up the internal	 * write buffer in one go, the TX IRQ should assert, at which	 * point we switch to fully interrupt-driven TX.	 */ 	mps2_uart_tx_chars(port);} static void mps2_uart_stop_rx(struct uart_port *port){	u8 control = mps2_uart_read8(port, UARTn_CTRL); 	control &= ~UARTn_CTRL_RX_GRP; 	mps2_uart_write8(port, control, UARTn_CTRL);} static void mps2_uart_break_ctl(struct uart_port *port, int ctl){} static void mps2_uart_rx_chars(struct uart_port *port){	struct tty_port *tport = &port->state->port; 	while (mps2_uart_read8(port, UARTn_STATE) & UARTn_STATE_RX_FULL) {		u8 rxdata = mps2_uart_read8(port, UARTn_DATA); 		port->icount.rx++;		tty_insert_flip_char(&port->state->port, rxdata, TTY_NORMAL);	} 	tty_flip_buffer_push(tport);} static irqreturn_t mps2_uart_rxirq(int irq, void *data){	struct uart_port *port = data;	u8 irqflag = mps2_uart_read8(port, UARTn_INT); 	if (unlikely(!(irqflag & UARTn_INT_RX)))		return IRQ_NONE; 	uart_port_lock(port); 	mps2_uart_write8(port, UARTn_INT_RX, UARTn_INT);	mps2_uart_rx_chars(port); 	uart_port_unlock(port); 	return IRQ_HANDLED;} static irqreturn_t mps2_uart_txirq(int irq, void *data){	struct uart_port *port = data;	u8 irqflag = mps2_uart_read8(port, UARTn_INT); 	if (unlikely(!(irqflag & UARTn_INT_TX)))		return IRQ_NONE; 	uart_port_lock(port); 	mps2_uart_write8(port, UARTn_INT_TX, UARTn_INT);	mps2_uart_tx_chars(port); 	uart_port_unlock(port); 	return IRQ_HANDLED;} static irqreturn_t mps2_uart_oerrirq(int irq, void *data){	irqreturn_t handled = IRQ_NONE;	struct uart_port *port = data;	u8 irqflag = mps2_uart_read8(port, UARTn_INT); 	uart_port_lock(port); 	if (irqflag & UARTn_INT_RX_OVERRUN) {		struct tty_port *tport = &port->state->port; 		mps2_uart_write8(port, UARTn_INT_RX_OVERRUN, UARTn_INT);		port->icount.overrun++;		tty_insert_flip_char(tport, 0, TTY_OVERRUN);		tty_flip_buffer_push(tport);		handled = IRQ_HANDLED;	} 	/*	 * It's never been seen in practice and it never *should* happen since	 * we check if there is enough room in TX buffer before sending data.	 * So we keep this check in case something suspicious has happened.	 */	if (irqflag & UARTn_INT_TX_OVERRUN) {		mps2_uart_write8(port, UARTn_INT_TX_OVERRUN, UARTn_INT);		handled = IRQ_HANDLED;	} 	uart_port_unlock(port); 	return handled;} static irqreturn_t mps2_uart_combinedirq(int irq, void *data){	if (mps2_uart_rxirq(irq, data) == IRQ_HANDLED)		return IRQ_HANDLED; 	if (mps2_uart_txirq(irq, data) == IRQ_HANDLED)		return IRQ_HANDLED; 	if (mps2_uart_oerrirq(irq, data) == IRQ_HANDLED)		return IRQ_HANDLED; 	return IRQ_NONE;} static int mps2_uart_startup(struct uart_port *port){	struct mps2_uart_port *mps_port = to_mps2_port(port);	u8 control = mps2_uart_read8(port, UARTn_CTRL);	int ret; 	control &= ~(UARTn_CTRL_RX_GRP | UARTn_CTRL_TX_GRP); 	mps2_uart_write8(port, control, UARTn_CTRL); 	if (mps_port->flags & UART_PORT_COMBINED_IRQ) {		ret = request_irq(port->irq, mps2_uart_combinedirq, 0,				  MAKE_NAME(-combined), mps_port); 		if (ret) {			dev_err(port->dev, "failed to register combinedirq (%d)\n", ret);			return ret;		}	} else {		ret = request_irq(port->irq, mps2_uart_oerrirq, IRQF_SHARED,				  MAKE_NAME(-overrun), mps_port); 		if (ret) {			dev_err(port->dev, "failed to register oerrirq (%d)\n", ret);			return ret;		} 		ret = request_irq(mps_port->rx_irq, mps2_uart_rxirq, 0,				  MAKE_NAME(-rx), mps_port);		if (ret) {			dev_err(port->dev, "failed to register rxirq (%d)\n", ret);			goto err_free_oerrirq;		} 		ret = request_irq(mps_port->tx_irq, mps2_uart_txirq, 0,				  MAKE_NAME(-tx), mps_port);		if (ret) {			dev_err(port->dev, "failed to register txirq (%d)\n", ret);			goto err_free_rxirq;		} 	} 	control |= UARTn_CTRL_RX_GRP | UARTn_CTRL_TX_GRP; 	mps2_uart_write8(port, control, UARTn_CTRL); 	return 0; err_free_rxirq:	free_irq(mps_port->rx_irq, mps_port);err_free_oerrirq:	free_irq(port->irq, mps_port); 	return ret;} static void mps2_uart_shutdown(struct uart_port *port){	struct mps2_uart_port *mps_port = to_mps2_port(port);	u8 control = mps2_uart_read8(port, UARTn_CTRL); 	control &= ~(UARTn_CTRL_RX_GRP | UARTn_CTRL_TX_GRP); 	mps2_uart_write8(port, control, UARTn_CTRL); 	if (!(mps_port->flags & UART_PORT_COMBINED_IRQ)) {		free_irq(mps_port->rx_irq, mps_port);		free_irq(mps_port->tx_irq, mps_port);	} 	free_irq(port->irq, mps_port);} static voidmps2_uart_set_termios(struct uart_port *port, struct ktermios *termios,		      const struct ktermios *old){	unsigned long flags;	unsigned int baud, bauddiv; 	termios->c_cflag &= ~(CRTSCTS | CMSPAR);	termios->c_cflag &= ~CSIZE;	termios->c_cflag |= CS8;	termios->c_cflag &= ~PARENB;	termios->c_cflag &= ~CSTOPB; 	baud = uart_get_baud_rate(port, termios, old,			DIV_ROUND_CLOSEST(port->uartclk, UARTn_BAUDDIV_MASK),			DIV_ROUND_CLOSEST(port->uartclk, 16)); 	bauddiv = DIV_ROUND_CLOSEST(port->uartclk, baud); 	uart_port_lock_irqsave(port, &flags); 	uart_update_timeout(port, termios->c_cflag, baud);	mps2_uart_write32(port, bauddiv, UARTn_BAUDDIV); 	uart_port_unlock_irqrestore(port, flags); 	if (tty_termios_baud_rate(termios))		tty_termios_encode_baud_rate(termios, baud, baud);} static const char *mps2_uart_type(struct uart_port *port){	return (port->type == PORT_MPS2UART) ? DRIVER_NAME : NULL;} static void mps2_uart_release_port(struct uart_port *port){} static int mps2_uart_request_port(struct uart_port *port){	return 0;} static void mps2_uart_config_port(struct uart_port *port, int type){	if (type & UART_CONFIG_TYPE && !mps2_uart_request_port(port))		port->type = PORT_MPS2UART;} static int mps2_uart_verify_port(struct uart_port *port, struct serial_struct *serinfo){	return -EINVAL;} static const struct uart_ops mps2_uart_pops = {	.tx_empty = mps2_uart_tx_empty,	.set_mctrl = mps2_uart_set_mctrl,	.get_mctrl = mps2_uart_get_mctrl,	.stop_tx = mps2_uart_stop_tx,	.start_tx = mps2_uart_start_tx,	.stop_rx = mps2_uart_stop_rx,	.break_ctl = mps2_uart_break_ctl,	.startup = mps2_uart_startup,	.shutdown = mps2_uart_shutdown,	.set_termios = mps2_uart_set_termios,	.type = mps2_uart_type,	.release_port = mps2_uart_release_port,	.request_port = mps2_uart_request_port,	.config_port = mps2_uart_config_port,	.verify_port = mps2_uart_verify_port,}; static DEFINE_IDR(ports_idr); #ifdef CONFIG_SERIAL_MPS2_UART_CONSOLEstatic void mps2_uart_console_putchar(struct uart_port *port, unsigned char ch){	while (mps2_uart_read8(port, UARTn_STATE) & UARTn_STATE_TX_FULL)		cpu_relax(); 	mps2_uart_write8(port, ch, UARTn_DATA);} static void mps2_uart_console_write(struct console *co, const char *s, unsigned int cnt){	struct mps2_uart_port *mps_port = idr_find(&ports_idr, co->index);	struct uart_port *port = &mps_port->port; 	uart_console_write(port, s, cnt, mps2_uart_console_putchar);} static int mps2_uart_console_setup(struct console *co, char *options){	struct mps2_uart_port *mps_port;	int baud = 9600;	int bits = 8;	int parity = 'n';	int flow = 'n'; 	if (co->index < 0 || co->index >= MPS2_MAX_PORTS)		return -ENODEV; 	mps_port = idr_find(&ports_idr, co->index); 	if (!mps_port)		return -ENODEV; 	if (options)		uart_parse_options(options, &baud, &parity, &bits, &flow); 	return uart_set_options(&mps_port->port, co, baud, parity, bits, flow);} static struct uart_driver mps2_uart_driver; static struct console mps2_uart_console = {	.name = SERIAL_NAME,	.device = uart_console_device,	.write = mps2_uart_console_write,	.setup = mps2_uart_console_setup,	.flags = CON_PRINTBUFFER,	.index = -1,	.data = &mps2_uart_driver,}; #define MPS2_SERIAL_CONSOLE (&mps2_uart_console) static void mps2_early_putchar(struct uart_port *port, unsigned char ch){	while (readb(port->membase + UARTn_STATE) & UARTn_STATE_TX_FULL)		cpu_relax(); 	writeb((unsigned char)ch, port->membase + UARTn_DATA);} static void mps2_early_write(struct console *con, const char *s, unsigned int n){	struct earlycon_device *dev = con->data; 	uart_console_write(&dev->port, s, n, mps2_early_putchar);} static int __init mps2_early_console_setup(struct earlycon_device *device,					   const char *opt){	if (!device->port.membase)		return -ENODEV; 	device->con->write = mps2_early_write; 	return 0;} OF_EARLYCON_DECLARE(mps2, "arm,mps2-uart", mps2_early_console_setup); #else#define MPS2_SERIAL_CONSOLE NULL#endif static struct uart_driver mps2_uart_driver = {

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