path: root/drivers/tty/serial/cpm_uart.c

// SPDX-License-Identifier: GPL-2.0+
/*
 *  Driver for CPM (SCC/SMC) serial ports; core driver
 *
 *  Based on arch/ppc/cpm2_io/uart.c by Dan Malek
 *  Based on ppc8xx.c by Thomas Gleixner
 *  Based on drivers/serial/amba.c by Russell King
 *
 *  Maintainer: Kumar Gala (galak@kernel.crashing.org) (CPM2)
 *              Pantelis Antoniou (panto@intracom.gr) (CPM1)
 *
 *  Copyright (C) 2004, 2007 Freescale Semiconductor, Inc.
 *            (C) 2004 Intracom, S.A.
 *            (C) 2005-2006 MontaVista Software, Inc.
 *		Vitaly Bordug <vbordug@ru.mvista.com>
 */

#include <linux/module.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/ioport.h>
#include <linux/init.h>
#include <linux/serial.h>
#include <linux/console.h>
#include <linux/sysrq.h>
#include <linux/device.h>
#include <linux/memblock.h>
#include <linux/dma-mapping.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/of_platform.h>
#include <linux/gpio/consumer.h>
#include <linux/clk.h>

#include <sysdev/fsl_soc.h>

#include <asm/io.h>
#include <asm/irq.h>
#include <asm/delay.h>
#include <asm/udbg.h>

#include <linux/serial_core.h>
#include <linux/kernel.h>

#include "cpm_uart.h"


/**************************************************************/

static int  cpm_uart_tx_pump(struct uart_port *port);
static void cpm_uart_initbd(struct uart_cpm_port *pinfo);

/**************************************************************/

#define HW_BUF_SPD_THRESHOLD    2400

static void cpm_line_cr_cmd(struct uart_cpm_port *port, int cmd)
{
	cpm_command(port->command, cmd);
}

/*
 * Check, if transmit buffers are processed
*/
static unsigned int cpm_uart_tx_empty(struct uart_port *port)
{
	struct uart_cpm_port *pinfo =
		container_of(port, struct uart_cpm_port, port);
	cbd_t __iomem *bdp = pinfo->tx_bd_base;
	int ret = 0;

	while (1) {
		if (in_be16(&bdp->cbd_sc) & BD_SC_READY)
			break;

		if (in_be16(&bdp->cbd_sc) & BD_SC_WRAP) {
			ret = TIOCSER_TEMT;
			break;
		}
		bdp++;
	}

	pr_debug("CPM uart[%d]:tx_empty: %d\n", port->line, ret);

	return ret;
}

static void cpm_uart_set_mctrl(struct uart_port *port, unsigned int mctrl)
{
	struct uart_cpm_port *pinfo =
		container_of(port, struct uart_cpm_port, port);

	if (pinfo->gpios[GPIO_RTS])
		gpiod_set_value(pinfo->gpios[GPIO_RTS], !(mctrl & TIOCM_RTS));

	if (pinfo->gpios[GPIO_DTR])
		gpiod_set_value(pinfo->gpios[GPIO_DTR], !(mctrl & TIOCM_DTR));
}

static unsigned int cpm_uart_get_mctrl(struct uart_port *port)
{
	struct uart_cpm_port *pinfo =
		container_of(port, struct uart_cpm_port, port);
	unsigned int mctrl = TIOCM_CTS | TIOCM_DSR | TIOCM_CAR;

	if (pinfo->gpios[GPIO_CTS]) {
		if (gpiod_get_value(pinfo->gpios[GPIO_CTS]))
			mctrl &= ~TIOCM_CTS;
	}

	if (pinfo->gpios[GPIO_DSR]) {
		if (gpiod_get_value(pinfo->gpios[GPIO_DSR]))
			mctrl &= ~TIOCM_DSR;
	}

	if (pinfo->gpios[GPIO_DCD]) {
		if (gpiod_get_value(pinfo->gpios[GPIO_DCD]))
			mctrl &= ~TIOCM_CAR;
	}

	if (pinfo->gpios[GPIO_RI]) {
		if (!gpiod_get_value(pinfo->gpios[GPIO_RI]))
			mctrl |= TIOCM_RNG;
	}

	return mctrl;
}

/*
 * Stop transmitter
 */
static void cpm_uart_stop_tx(struct uart_port *port)
{
	struct uart_cpm_port *pinfo =
		container_of(port, struct uart_cpm_port, port);
	smc_t __iomem *smcp = pinfo->smcp;
	scc_t __iomem *sccp = pinfo->sccp;

	pr_debug("CPM uart[%d]:stop tx\n", port->line);

	if (IS_SMC(pinfo))
		clrbits8(&smcp->smc_smcm, SMCM_TX);
	else
		clrbits16(&sccp->scc_sccm, UART_SCCM_TX);
}

/*
 * Start transmitter
 */
static void cpm_uart_start_tx(struct uart_port *port)
{
	struct uart_cpm_port *pinfo =
		container_of(port, struct uart_cpm_port, port);
	smc_t __iomem *smcp = pinfo->smcp;
	scc_t __iomem *sccp = pinfo->sccp;

	pr_debug("CPM uart[%d]:start tx\n", port->line);

	if (IS_SMC(pinfo)) {
		if (in_8(&smcp->smc_smcm) & SMCM_TX)
			return;
	} else {
		if (in_be16(&sccp->scc_sccm) & UART_SCCM_TX)
			return;
	}

	if (cpm_uart_tx_pump(port) != 0) {
		if (IS_SMC(pinfo)) {
			setbits8(&smcp->smc_smcm, SMCM_TX);
		} else {
			setbits16(&sccp->scc_sccm, UART_SCCM_TX);
		}
	}
}

/*
 * Stop receiver
 */
static void cpm_uart_stop_rx(struct uart_port *port)
{
	struct uart_cpm_port *pinfo =
		container_of(port, struct uart_cpm_port, port);
	smc_t __iomem *smcp = pinfo->smcp;
	scc_t __iomem *sccp = pinfo->sccp;

	pr_debug("CPM uart[%d]:stop rx\n", port->line);

	if (IS_SMC(pinfo))
		clrbits8(&smcp->smc_smcm, SMCM_RX);
	else
		clrbits16(&sccp->scc_sccm, UART_SCCM_RX);
}

/*
 * Generate a break.
 */
static void cpm_uart_break_ctl(struct uart_port *port, int break_state)
{
	struct uart_cpm_port *pinfo =
		container_of(port, struct uart_cpm_port, port);

	pr_debug("CPM uart[%d]:break ctrl, break_state: %d\n", port->line,
		break_state);

	if (break_state)
		cpm_line_cr_cmd(pinfo, CPM_CR_STOP_TX);
	else
		cpm_line_cr_cmd(pinfo, CPM_CR_RESTART_TX);
}

/*
 * Transmit characters, refill buffer descriptor, if possible
 */
static void cpm_uart_i