xref: /openbmc/u-boot/drivers/serial/serial_pl01x.c (revision aed2fbef5e9a0ab5a7cd01e742039a962f0b24ef)

/*
 * (C) Copyright 2000
 * Rob Taylor, Flying Pig Systems. robt@flyingpig.com.
 *
 * (C) Copyright 2004
 * ARM Ltd.
 * Philippe Robin, <philippe.robin@arm.com>
 *
 * SPDX-License-Identifier:	GPL-2.0+
 */

/* Simple U-Boot driver for the PrimeCell PL010/PL011 UARTs */

#include <common.h>
#include <errno.h>
#include <watchdog.h>
#include <asm/io.h>
#include <serial.h>
#include <serial_pl01x.h>
#include <linux/compiler.h>
#include "serial_pl01x_internal.h"

static volatile unsigned char *const port[] = CONFIG_PL01x_PORTS;
static enum pl01x_type pl01x_type __attribute__ ((section(".data")));
static struct pl01x_regs *base_regs __attribute__ ((section(".data")));
#define NUM_PORTS (sizeof(port)/sizeof(port[0]))

DECLARE_GLOBAL_DATA_PTR;

static int pl01x_putc(struct pl01x_regs *regs, char c)
{
	/* Wait until there is space in the FIFO */
	if (readl(&regs->fr) & UART_PL01x_FR_TXFF)
		return -EAGAIN;

	/* Send the character */
	writel(c, &regs->dr);

	return 0;
}

static int pl01x_getc(struct pl01x_regs *regs)
{
	unsigned int data;

	/* Wait until there is data in the FIFO */
	if (readl(&regs->fr) & UART_PL01x_FR_RXFE)
		return -EAGAIN;

	data = readl(&regs->dr);

	/* Check for an error flag */
	if (data & 0xFFFFFF00) {
		/* Clear the error */
		writel(0xFFFFFFFF, &regs->ecr);
		return -1;
	}

	return (int) data;
}

static int pl01x_tstc(struct pl01x_regs *regs)
{
	WATCHDOG_RESET();
	return !(readl(&regs->fr) & UART_PL01x_FR_RXFE);
}

static int pl01x_generic_serial_init(struct pl01x_regs *regs,
				     enum pl01x_type type)
{
	unsigned int lcr;

#ifdef CONFIG_PL011_SERIAL_FLUSH_ON_INIT
	if (type == TYPE_PL011) {
		/* Empty RX fifo if necessary */
		if (readl(&regs->pl011_cr) & UART_PL011_CR_UARTEN) {
			while (!(readl(&regs->fr) & UART_PL01x_FR_RXFE))
				readl(&regs->dr);
		}
	}
#endif

	/* First, disable everything */
	writel(0, &regs->pl010_cr);

	/* Set the UART to be 8 bits, 1 stop bit, no parity, fifo enabled */
	lcr = UART_PL011_LCRH_WLEN_8 | UART_PL011_LCRH_FEN;
	writel(lcr, &regs->pl011_lcrh);

	switch (type) {
	case TYPE_PL010:
		break;
	case TYPE_PL011: {
#ifdef CONFIG_PL011_SERIAL_RLCR
		int i;

		/*
		 * Program receive line control register after waiting
		 * 10 bus cycles.  Delay be writing to readonly register
		 * 10 times
		 */
		for (i = 0; i < 10; i++)
			writel(lcr, &regs->fr);

		writel(lcr, &regs->pl011_rlcr);
		/* lcrh needs to be set again for change to be effective */
		writel(lcr, &regs->pl011_lcrh);
#endif
		break;
	}
	default:
		return -EINVAL;
	}

	return 0;
}

static int pl01x_generic_setbrg(struct pl01x_regs *regs, enum pl01x_type type,
				int clock, int baudrate)
{
	switch (type) {
	case TYPE_PL010: {
		unsigned int divisor;

		switch (baudrate) {
		case 9600:
			divisor = UART_PL010_BAUD_9600;
			break;
		case 19200:
			divisor = UART_PL010_BAUD_9600;
			break;
		case 38400:
			divisor = UART_PL010_BAUD_38400;
			break;
		case 57600:
			divisor = UART_PL010_BAUD_57600;
			break;
		case 115200:
			divisor = UART_PL010_BAUD_115200;
			break;
		default:
			divisor = UART_PL010_BAUD_38400;
		}

		writel((divisor & 0xf00) >> 8, &regs->pl010_lcrm);
		writel(divisor & 0xff, &regs->pl010_lcrl);

		/* Finally, enable the UART */
		writel(UART_PL010_CR_UARTEN, &regs->pl010_cr);
		break;
	}
	case TYPE_PL011: {
		unsigned int temp;
		unsigned int divider;
		unsigned int remainder;
		unsigned int fraction;

		/*
		* Set baud rate
		*
		* IBRD = UART_CLK / (16 * BAUD_RATE)
		* FBRD = RND((64 * MOD(UART_CLK,(16 * BAUD_RATE)))
		*		/ (16 * BAUD_RATE))
		*/
		temp = 16 * baudrate;
		divider = clock / temp;
		remainder = clock % temp;
		temp = (8 * remainder) / baudrate;
		fraction = (temp >> 1) + (temp & 1);

		writel(divider, &regs->pl011_ibrd);
		writel(fraction, &regs->pl011_fbrd);

		/* Finally, enable the UART */
		writel(UART_PL011_CR_UARTEN | UART_PL011_CR_TXE |
		       UART_PL011_CR_RXE | UART_PL011_CR_RTS, &regs->pl011_cr);
		break;
	}
	default:
		return -EINVAL;
	}

	return 0;
}

#ifndef CONFIG_DM_SERIAL
static void pl01x_serial_init_baud(int baudrate)
{
	int clock = 0;

#if defined(CONFIG_PL010_SERIAL)
	pl01x_type = TYPE_PL010;
#elif defined(CONFIG_PL011_SERIAL)
	pl01x_type = TYPE_PL011;
	clock = CONFIG_PL011_CLOCK;
#endif
	base_regs = (struct pl01x_regs *)port[CONFIG_CONS_INDEX];

	pl01x_generic_serial_init(base_regs, pl01x_type);
	pl01x_generic_setbrg(base_regs, TYPE_PL010, clock, baudrate);
}

/*
 * Integrator AP has two UARTs, we use the first one, at 38400-8-N-1
 * Integrator CP has two UARTs, use the first one, at 38400-8-N-1
 * Versatile PB has four UARTs.
 */
int pl01x_serial_init(void)
{
	pl01x_serial_init_baud(CONFIG_BAUDRATE);

	return 0;
}

static void pl01x_serial_putc(const char c)
{
	if (c == '\n')
		while (pl01x_putc(base_regs, '\r') == -EAGAIN);

	while (pl01x_putc(base_regs, c) == -EAGAIN);
}

static int pl01x_serial_getc(void)
{
	while (1) {
		int ch = pl01x_getc(base_regs);

		if (ch == -EAGAIN) {
			WATCHDOG_RESET();
			continue;
		}

		return ch;
	}
}

static int pl01x_serial_tstc(void)
{
	return pl01x_tstc(base_regs);
}

static void pl01x_serial_setbrg(void)
{
	/*
	 * Flush FIFO and wait for non-busy before changing baudrate to avoid
	 * crap in console
	 */
	while (!(readl(&base_regs->fr) & UART_PL01x_FR_TXFE))
		WATCHDOG_RESET();
	while (readl(&base_regs->fr) & UART_PL01x_FR_BUSY)
		WATCHDOG_RESET();
	pl01x_serial_init_baud(gd->baudrate);
}

static struct serial_device pl01x_serial_drv = {
	.name	= "pl01x_serial",
	.start	= pl01x_serial_init,
	.stop	= NULL,
	.setbrg	= pl01x_serial_setbrg,
	.putc	= pl01x_serial_putc,
	.puts	= default_serial_puts,
	.getc	= pl01x_serial_getc,
	.tstc	= pl01x_serial_tstc,
};

void pl01x_serial_initialize(void)
{
	serial_register(&pl01x_serial_drv);
}

__weak struct serial_device *default_serial_console(void)
{
	return &pl01x_serial_drv;
}

#endif /* nCONFIG_DM_SERIAL */