u-boot/drivers/serial/serial_omap.c

// SPDX-License-Identifier: GPL-2.0+
/*
 * Texas Instruments' OMAP serial driver
 *
 * Copyright (C) 2018 Texas Instruments Incorporated - https://www.ti.com/
 *	Lokesh Vutla <lokeshvutla@ti.com>
 */

#include <config.h>
#include <dm.h>
#include <dt-structs.h>
#include <log.h>
#include <ns16550.h>
#include <serial.h>
#include <clk.h>
#include <linux/err.h>

/*
 * These are the definitions for the MDR1 register
 */
#define UART_OMAP_MDR1_16X_MODE		0x00	/* UART 16x mode */
#define UART_OMAP_MDR1_13X_MODE		0x03	/* UART 13x mode */

#ifndef CFG_SYS_NS16550_CLK
#define CFG_SYS_NS16550_CLK  0
#endif

#ifdef CONFIG_DEBUG_UART_OMAP

#ifndef CFG_SYS_NS16550_IER
#define CFG_SYS_NS16550_IER  0x00
#endif

#define UART_MCRVAL 0x00
#define UART_LCRVAL UART_LCR_8N1

static inline void serial_out_shift(void *addr, int shift, int value)
{
#ifdef CONFIG_SYS_NS16550_PORT_MAPPED
	outb(value, (ulong)addr);
#elif defined(CONFIG_SYS_NS16550_MEM32) && defined(CONFIG_SYS_LITTLE_ENDIAN)
	out_le32(addr, value);
#elif defined(CONFIG_SYS_NS16550_MEM32) && defined(CONFIG_SYS_BIG_ENDIAN)
	out_be32(addr, value);
#elif defined(CONFIG_SYS_NS16550_MEM32)
	writel(value, addr);
#elif defined(CONFIG_SYS_BIG_ENDIAN)
	writeb(value, addr + (1 << shift) - 1);
#else
	writeb(value, addr);
#endif
}

static inline int serial_in_shift(void *addr, int shift)
{
#ifdef CONFIG_SYS_NS16550_PORT_MAPPED
	return inb((ulong)addr);
#elif defined(CONFIG_SYS_NS16550_MEM32) && defined(CONFIG_SYS_LITTLE_ENDIAN)
	return in_le32(addr);
#elif defined(CONFIG_SYS_NS16550_MEM32) && defined(CONFIG_SYS_BIG_ENDIAN)
	return in_be32(addr);
#elif defined(CONFIG_SYS_NS16550_MEM32)
	return readl(addr);
#elif defined(CONFIG_SYS_BIG_ENDIAN)
	return readb(addr + (1 << shift) - 1);
#else
	return readb(addr);
#endif
}

#include <debug_uart.h>

static inline void _debug_uart_init(void)
{
	struct ns16550 *com_port = (struct ns16550 *)CONFIG_VAL(DEBUG_UART_BASE);
	int baud_divisor;

	baud_divisor = ns16550_calc_divisor(com_port, CONFIG_DEBUG_UART_CLOCK,
					    CONFIG_BAUDRATE);
	serial_dout(&com_port->ier, CFG_SYS_NS16550_IER);
	serial_dout(&com_port->mdr1, 0x7);
	serial_dout(&com_port->mcr, UART_MCRVAL);
	serial_dout(&com_port->fcr, UART_FCR_DEFVAL);

	serial_dout(&com_port->lcr, UART_LCR_BKSE | UART_LCRVAL);
	serial_dout(&com_port->dll, baud_divisor & 0xff);
	serial_dout(&com_port->dlm, (baud_divisor >> 8) & 0xff);
	serial_dout(&com_port->lcr, UART_LCRVAL);
	serial_dout(&com_port->mdr1, 0x0);
}

static inline void _debug_uart_putc(int ch)
{
	struct ns16550 *com_port = (struct ns16550 *)CONFIG_VAL(DEBUG_UART_BASE);

	while (!(serial_din(&com_port->lsr) & UART_LSR_THRE))
		;
	serial_dout(&com_port->thr, ch);
}

DEBUG_UART_FUNCS

#endif

#if CONFIG_IS_ENABLED(DM_SERIAL)

#if CONFIG_IS_ENABLED(OF_REAL) && CONFIG_IS_ENABLED(SERIAL_PRESENT)
static int omap_serial_of_to_plat(struct udevice *dev)
{
	struct ns16550_plat *plat = dev_get_plat(dev);
	fdt_addr_t addr;
	struct clk clk;
	int err;

	/* try Processor Local Bus device first */
	addr = dev_read_addr(dev);
	if (addr == FDT_ADDR_T_NONE)
		return -EINVAL;

	plat->base = (unsigned long)map_physmem(addr, 0, MAP_NOCACHE);

	plat->reg_offset = dev_read_u32_default(dev, "reg-offset", 0);
	plat->reg_shift = 2;

	err = clk_get_by_index(dev, 0, &clk);
	if (!err) {
		err = clk_get_rate(&clk);
		if (!IS_ERR_VALUE(err))
			plat->clock = err;
	} else if (err != -ENOENT && err != -ENODEV && err != -ENOSYS) {
		debug("omap serial failed to get clock\n");
		return err;
	}

	if (!plat->clock)
		plat->clock = dev_read_u32_default(dev, "clock-frequency",
						   CFG_SYS_NS16550_CLK);
	if (!plat->clock) {
		debug("omap serial clock not defined\n");
		return -EINVAL;
	}

	plat->fcr = UART_FCR_DEFVAL;

	return 0;
}

static const struct udevice_id omap_serial_ids[] = {
	{ .compatible = "ti,omap2-uart", },
	{ .compatible = "ti,omap3-uart", },
	{ .compatible = "ti,omap4-uart", },
	{ .compatible = "ti,am3352-uart", },
	{ .compatible = "ti,am4372-uart", },
	{ .compatible = "ti,dra742-uart", },
	{ .compatible = "ti,am654-uart", },
	{}
};
#endif /* OF_REAL */

static int omap_serial_calc_divisor(struct ns16550 *com_port, int clock, int baudrate)
{
	unsigned int div_13, div_16;
	unsigned int abs_d13, abs_d16;
	/*
	 * The below logic sets the MDR1 register based on clock and baudrate.
	 */
	div_13 = DIV_ROUND_CLOSEST(clock, 13 * baudrate);
	div_16 = DIV_ROUND_CLOSEST(clock, 16 * baudrate);

	if (!div_13)
		div_13 = 1;
	if (!div_16)
		div_16 = 1;

	abs_d13 = abs(baudrate - clock / 13 / div_13);
	abs_d16 = abs(baudrate - clock / 16 / div_16);

	if (abs_d13 >= abs_d16)
		serial_out(UART_OMAP_MDR1_16X_MODE, &com_port->mdr1);
	else
		serial_out(UART_OMAP_MDR1_13X_MODE, &com_port->mdr1);

	return abs_d13 >= abs_d16 ? div_16 : div_13;
}

static int omap_serial_setbrg(struct udevice *dev, int baudrate)
{
	struct ns16550 *const com_port = dev_get_priv(dev);
	struct ns16550_plat *plat = com_port->plat;
	int clock_divisor;

	clock_divisor = omap_serial_calc_divisor(com_port, plat->clock, baudrate);

	ns16550_setbrg(com_port, clock_divisor);

	return 0;
}

const struct dm_serial_ops omap_serial_ops = {
	.putc = ns16550_serial_putc,
	.pending = ns16550_serial_pending,
	.getc = ns16550_serial_getc,
	.setbrg = omap_serial_setbrg,
	.setconfig = ns16550_serial_setconfig,
	.getinfo = ns16550_serial_getinfo,
};

#if CONFIG_IS_ENABLED(SERIAL_PRESENT)
U_BOOT_DRIVER(omap_serial) = {
	.name	= "omap_serial",
	.id	= UCLASS_SERIAL,
#if CONFIG_IS_ENABLED(OF_REAL)
	.of_match = omap_serial_ids,
	.of_to_plat = omap_serial_of_to_plat,
	.plat_auto	= sizeof(struct ns16550_plat),
#endif
	.priv_auto	= sizeof(struct ns16550),
	.probe = ns16550_serial_probe,
	.ops	= &omap_serial_ops,
#if !CONFIG_IS_ENABLED(OF_CONTROL)
	.flags	= DM_FLAG_PRE_RELOC,
#endif
};
#endif
#endif /* DM_SERIAL */