drivers/serial/ns16550.c - filogic/uboot - Gitiles

 /*
  * COM1 NS16550 support
  * originally from linux source (arch/powerpc/boot/ns16550.c)
  * modified to use CONFIG_SYS_ISA_MEM and new defines
  */

 #include <common.h>
 #include <clk.h>
 #include <dm.h>
 #include <errno.h>
 #include <fdtdec.h>
 #include <ns16550.h>
 #include <serial.h>
 #include <watchdog.h>
 #include <linux/types.h>
 #include <asm/io.h>

 DECLARE_GLOBAL_DATA_PTR;

 #define UART_LCRVAL UART_LCR_8N1		/* 8 data, 1 stop, no parity */
 #define UART_MCRVAL (UART_MCR_DTR | \
 		     UART_MCR_RTS)		/* RTS/DTR */
 #define UART_FCRVAL (UART_FCR_FIFO_EN |	\
 		     UART_FCR_RXSR |	\
 		     UART_FCR_TXSR)		/* Clear & enable FIFOs */

 #ifndef CONFIG_DM_SERIAL
 #ifdef CONFIG_SYS_NS16550_PORT_MAPPED
 #define serial_out(x, y)	outb(x, (ulong)y)
 #define serial_in(y)		inb((ulong)y)
 #elif defined(CONFIG_SYS_NS16550_MEM32) && (CONFIG_SYS_NS16550_REG_SIZE > 0)
 #define serial_out(x, y)	out_be32(y, x)
 #define serial_in(y)		in_be32(y)
 #elif defined(CONFIG_SYS_NS16550_MEM32) && (CONFIG_SYS_NS16550_REG_SIZE < 0)
 #define serial_out(x, y)	out_le32(y, x)
 #define serial_in(y)		in_le32(y)
 #else
 #define serial_out(x, y)	writeb(x, y)
 #define serial_in(y)		readb(y)
 #endif
 #endif /* !CONFIG_DM_SERIAL */

 #if defined(CONFIG_SOC_KEYSTONE)
 #define UART_REG_VAL_PWREMU_MGMT_UART_DISABLE   0
 #define UART_REG_VAL_PWREMU_MGMT_UART_ENABLE ((1 << 14) | (1 << 13) | (1 << 0))
 #undef UART_MCRVAL
 #ifdef CONFIG_SERIAL_HW_FLOW_CONTROL
 #define UART_MCRVAL             (UART_MCR_RTS | UART_MCR_AFE)
 #else
 #define UART_MCRVAL             (UART_MCR_RTS)
 #endif
 #endif

 #ifndef CONFIG_SYS_NS16550_IER
 #define CONFIG_SYS_NS16550_IER  0x00
 #endif /* CONFIG_SYS_NS16550_IER */

 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_BIG_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_BIG_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
 }

 #ifdef CONFIG_DM_SERIAL

 #ifndef CONFIG_SYS_NS16550_CLK
 #define CONFIG_SYS_NS16550_CLK  0
 #endif

 static void ns16550_writeb(NS16550_t port, int offset, int value)
 {
 	struct ns16550_platdata *plat = port->plat;
 	unsigned char *addr;

 	offset *= 1 << plat->reg_shift;
 	addr = (unsigned char *)plat->base + offset;

 	/*
 	 * As far as we know it doesn't make sense to support selection of
 	 * these options at run-time, so use the existing CONFIG options.
 	 */
 	serial_out_shift(addr + plat->reg_offset, plat->reg_shift, value);
 }

 static int ns16550_readb(NS16550_t port, int offset)
 {
 	struct ns16550_platdata *plat = port->plat;
 	unsigned char *addr;

 	offset *= 1 << plat->reg_shift;
 	addr = (unsigned char *)plat->base + offset;

 	return serial_in_shift(addr + plat->reg_offset, plat->reg_shift);
 }

 /* We can clean these up once everything is moved to driver model */
 #define serial_out(value, addr)	\
 	ns16550_writeb(com_port, \
 		(unsigned char *)addr - (unsigned char *)com_port, value)
 #define serial_in(addr) \
 	ns16550_readb(com_port, \
 		(unsigned char *)addr - (unsigned char *)com_port)
 #endif

 int ns16550_calc_divisor(NS16550_t port, int clock, int baudrate)
 {
 	const unsigned int mode_x_div = 16;

 	return DIV_ROUND_CLOSEST(clock, mode_x_div * baudrate);
 }

 static void NS16550_setbrg(NS16550_t com_port, int baud_divisor)
 {
 	serial_out(UART_LCR_BKSE | UART_LCRVAL, &com_port->lcr);
 	serial_out(baud_divisor & 0xff, &com_port->dll);
 	serial_out((baud_divisor >> 8) & 0xff, &com_port->dlm);
 	serial_out(UART_LCRVAL, &com_port->lcr);
 }

 void NS16550_init(NS16550_t com_port, int baud_divisor)
 {
 #if (defined(CONFIG_SPL_BUILD) && \
 		(defined(CONFIG_OMAP34XX) || defined(CONFIG_OMAP44XX)))
 	/*
 	 * On some OMAP3/OMAP4 devices when UART3 is configured for boot mode
 	 * before SPL starts only THRE bit is set. We have to empty the
 	 * transmitter before initialization starts.
 	 */
 	if ((serial_in(&com_port->lsr) & (UART_LSR_TEMT | UART_LSR_THRE))
 	     == UART_LSR_THRE) {
 		if (baud_divisor != -1)
 			NS16550_setbrg(com_port, baud_divisor);
 		serial_out(0, &com_port->mdr1);
 	}
 #endif

 	while (!(serial_in(&com_port->lsr) & UART_LSR_TEMT))
 		;

 	serial_out(CONFIG_SYS_NS16550_IER, &com_port->ier);
 #if defined(CONFIG_OMAP) || defined(CONFIG_AM33XX) || \
 			defined(CONFIG_TI81XX) || defined(CONFIG_AM43XX)
 	serial_out(0x7, &com_port->mdr1);	/* mode select reset TL16C750*/
 #endif
 	serial_out(UART_MCRVAL, &com_port->mcr);
 	serial_out(UART_FCRVAL, &com_port->fcr);
 	if (baud_divisor != -1)
 		NS16550_setbrg(com_port, baud_divisor);
 #if defined(CONFIG_OMAP) || \
 	defined(CONFIG_AM33XX) || defined(CONFIG_SOC_DA8XX) || \
 	defined(CONFIG_TI81XX) || defined(CONFIG_AM43XX)

 	/* /16 is proper to hit 115200 with 48MHz */
 	serial_out(0, &com_port->mdr1);
 #endif /* CONFIG_OMAP */
 #if defined(CONFIG_SOC_KEYSTONE)
 	serial_out(UART_REG_VAL_PWREMU_MGMT_UART_ENABLE, &com_port->regC);
 #endif
 }

 #ifndef CONFIG_NS16550_MIN_FUNCTIONS
 void NS16550_reinit(NS16550_t com_port, int baud_divisor)
 {
 	serial_out(CONFIG_SYS_NS16550_IER, &com_port->ier);
 	NS16550_setbrg(com_port, 0);
 	serial_out(UART_MCRVAL, &com_port->mcr);
 	serial_out(UART_FCRVAL, &com_port->fcr);
 	NS16550_setbrg(com_port, baud_divisor);
 }
 #endif /* CONFIG_NS16550_MIN_FUNCTIONS */

 void NS16550_putc(NS16550_t com_port, char c)
 {
 	while ((serial_in(&com_port->lsr) & UART_LSR_THRE) == 0)
 		;
 	serial_out(c, &com_port->thr);

 	/*
 	 * Call watchdog_reset() upon newline. This is done here in putc
 	 * since the environment code uses a single puts() to print the complete
 	 * environment upon "printenv". So we can't put this watchdog call
 	 * in puts().
 	 */
 	if (c == '\n')
 		WATCHDOG_RESET();
 }

 #ifndef CONFIG_NS16550_MIN_FUNCTIONS
 char NS16550_getc(NS16550_t com_port)
 {
 	while ((serial_in(&com_port->lsr) & UART_LSR_DR) == 0) {
 #if !defined(CONFIG_SPL_BUILD) && defined(CONFIG_USB_TTY)
 		extern void usbtty_poll(void);
 		usbtty_poll();
 #endif
 		WATCHDOG_RESET();
 	}
 	return serial_in(&com_port->rbr);
 }

 int NS16550_tstc(NS16550_t com_port)
 {
 	return (serial_in(&com_port->lsr) & UART_LSR_DR) != 0;
 }

 #endif /* CONFIG_NS16550_MIN_FUNCTIONS */

 #ifdef CONFIG_DEBUG_UART_NS16550

 #include <debug_uart.h>

 #define serial_dout(reg, value)	\
 	serial_out_shift((char *)com_port + \
 		((char *)reg - (char *)com_port) * \
 			(1 << CONFIG_DEBUG_UART_SHIFT), \
 		CONFIG_DEBUG_UART_SHIFT, value)
 #define serial_din(reg) \
 	serial_in_shift((char *)com_port + \
 		((char *)reg - (char *)com_port) * \
 			(1 << CONFIG_DEBUG_UART_SHIFT), \
 		CONFIG_DEBUG_UART_SHIFT)

 static inline void _debug_uart_init(void)
 {
 	struct NS16550 *com_port = (struct NS16550 *)CONFIG_DEBUG_UART_BASE;
 	int baud_divisor;

 	/*
 	 * We copy the code from above because it is already horribly messy.
 	 * Trying to refactor to nicely remove the duplication doesn't seem
 	 * feasible. The better fix is to move all users of this driver to
 	 * driver model.
 	 */
 	baud_divisor = ns16550_calc_divisor(com_port, CONFIG_DEBUG_UART_CLOCK,
 					    CONFIG_BAUDRATE);
 	serial_dout(&com_port->ier, CONFIG_SYS_NS16550_IER);
 	serial_dout(&com_port->mcr, UART_MCRVAL);
 	serial_dout(&com_port->fcr, UART_FCRVAL);

 	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);
 }

 static inline void _debug_uart_putc(int ch)
 {
 	struct NS16550 *com_port = (struct NS16550 *)CONFIG_DEBUG_UART_BASE;

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

 DEBUG_UART_FUNCS

 #endif

 #ifdef CONFIG_DM_SERIAL
 static int ns16550_serial_putc(struct udevice *dev, const char ch)
 {
 	struct NS16550 *const com_port = dev_get_priv(dev);

 	if (!(serial_in(&com_port->lsr) & UART_LSR_THRE))
 		return -EAGAIN;
 	serial_out(ch, &com_port->thr);

 	/*
 	 * Call watchdog_reset() upon newline. This is done here in putc
 	 * since the environment code uses a single puts() to print the complete
 	 * environment upon "printenv". So we can't put this watchdog call
 	 * in puts().
 	 */
 	if (ch == '\n')
 		WATCHDOG_RESET();

 	return 0;
 }

 static int ns16550_serial_pending(struct udevice *dev, bool input)
 {
 	struct NS16550 *const com_port = dev_get_priv(dev);

 	if (input)
 		return serial_in(&com_port->lsr) & UART_LSR_DR ? 1 : 0;
 	else
 		return serial_in(&com_port->lsr) & UART_LSR_THRE ? 0 : 1;
 }

 static int ns16550_serial_getc(struct udevice *dev)
 {
 	struct NS16550 *const com_port = dev_get_priv(dev);

 	if (!(serial_in(&com_port->lsr) & UART_LSR_DR))
 		return -EAGAIN;

 	return serial_in(&com_port->rbr);
 }

 static int ns16550_serial_setbrg(struct udevice *dev, int baudrate)
 {
 	struct NS16550 *const com_port = dev_get_priv(dev);
 	struct ns16550_platdata *plat = com_port->plat;
 	int clock_divisor;

 	clock_divisor = ns16550_calc_divisor(com_port, plat->clock, baudrate);

 	NS16550_setbrg(com_port, clock_divisor);

 	return 0;
 }

 int ns16550_serial_probe(struct udevice *dev)
 {
 	struct NS16550 *const com_port = dev_get_priv(dev);

 	com_port->plat = dev_get_platdata(dev);
 	NS16550_init(com_port, -1);

 	return 0;
 }

 #if CONFIG_IS_ENABLED(OF_CONTROL) && !CONFIG_IS_ENABLED(OF_PLATDATA)
 int ns16550_serial_ofdata_to_platdata(struct udevice *dev)
 {
 	struct ns16550_platdata *plat = dev->platdata;
 	fdt_addr_t addr;
 	struct clk clk;
 	int err;

 	/* try Processor Local Bus device first */
 	addr = dev_get_addr(dev);
 #if defined(CONFIG_PCI) && defined(CONFIG_DM_PCI)
 	if (addr == FDT_ADDR_T_NONE) {
 		/* then try pci device */
 		struct fdt_pci_addr pci_addr;
 		u32 bar;
 		int ret;

 		/* we prefer to use a memory-mapped register */
 		ret = fdtdec_get_pci_addr(gd->fdt_blob, dev->of_offset,
 					  FDT_PCI_SPACE_MEM32, "reg",
 					  &pci_addr);
 		if (ret) {
 			/* try if there is any i/o-mapped register */
 			ret = fdtdec_get_pci_addr(gd->fdt_blob,
 						  dev->of_offset,
 						  FDT_PCI_SPACE_IO,
 						  "reg", &pci_addr);
 			if (ret)
 				return ret;
 		}

 		ret = fdtdec_get_pci_bar32(dev, &pci_addr, &bar);
 		if (ret)
 			return ret;

 		addr = bar;
 	}
 #endif

 	if (addr == FDT_ADDR_T_NONE)
 		return -EINVAL;

 #ifdef CONFIG_SYS_NS16550_PORT_MAPPED
 	plat->base = addr;
 #else
 	plat->base = (unsigned long)map_physmem(addr, 0, MAP_NOCACHE);
 #endif

 	plat->reg_offset = fdtdec_get_int(gd->fdt_blob, dev->of_offset,
 				     "reg-offset", 0);
 	plat->reg_shift = fdtdec_get_int(gd->fdt_blob, dev->of_offset,
 					 "reg-shift", 0);

 	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 != -ENODEV && err != -ENOSYS) {
 		debug("ns16550 failed to get clock\n");
 		return err;
 	}

 	if (!plat->clock)
 		plat->clock = fdtdec_get_int(gd->fdt_blob, dev->of_offset,
 					     "clock-frequency",
 					     CONFIG_SYS_NS16550_CLK);
 	if (!plat->clock) {
 		debug("ns16550 clock not defined\n");
 		return -EINVAL;
 	}

 	return 0;
 }
 #endif

 const struct dm_serial_ops ns16550_serial_ops = {
 	.putc = ns16550_serial_putc,
 	.pending = ns16550_serial_pending,
 	.getc = ns16550_serial_getc,
 	.setbrg = ns16550_serial_setbrg,
 };

 #if !CONFIG_IS_ENABLED(OF_PLATDATA)
 #if CONFIG_IS_ENABLED(OF_CONTROL)
 /*
  * Please consider existing compatible strings before adding a new
  * one to keep this table compact. Or you may add a generic "ns16550"
  * compatible string to your dts.
  */
 static const struct udevice_id ns16550_serial_ids[] = {
 	{ .compatible = "ns16550" },
 	{ .compatible = "ns16550a" },
 	{ .compatible = "nvidia,tegra20-uart" },
 	{ .compatible = "snps,dw-apb-uart" },
 	{ .compatible = "ti,omap2-uart" },
 	{ .compatible = "ti,omap3-uart" },
 	{ .compatible = "ti,omap4-uart" },
 	{ .compatible = "ti,am3352-uart" },
 	{ .compatible = "ti,am4372-uart" },
 	{ .compatible = "ti,dra742-uart" },
 	{}
 };
 #endif

 #if CONFIG_IS_ENABLED(SERIAL_PRESENT)
 U_BOOT_DRIVER(ns16550_serial) = {
 	.name	= "ns16550_serial",
 	.id	= UCLASS_SERIAL,
 #if CONFIG_IS_ENABLED(OF_CONTROL)
 	.of_match = ns16550_serial_ids,
 	.ofdata_to_platdata = ns16550_serial_ofdata_to_platdata,
 	.platdata_auto_alloc_size = sizeof(struct ns16550_platdata),
 #endif
 	.priv_auto_alloc_size = sizeof(struct NS16550),
 	.probe = ns16550_serial_probe,
 	.ops	= &ns16550_serial_ops,
 	.flags	= DM_FLAG_PRE_RELOC,
 };
 #endif
 #endif /* !OF_PLATDATA */
 #endif /* CONFIG_DM_SERIAL */
	/*
	* COM1 NS16550 support
	* originally from linux source (arch/powerpc/boot/ns16550.c)
	* modified to use CONFIG_SYS_ISA_MEM and new defines
	*/

	#include <common.h>
	#include <clk.h>
	#include <dm.h>
	#include <errno.h>
	#include <fdtdec.h>
	#include <ns16550.h>
	#include <serial.h>
	#include <watchdog.h>
	#include <linux/types.h>
	#include <asm/io.h>

	DECLARE_GLOBAL_DATA_PTR;

	#define UART_LCRVAL UART_LCR_8N1 /* 8 data, 1 stop, no parity */
	#define UART_MCRVAL (UART_MCR_DTR \| \
	UART_MCR_RTS) /* RTS/DTR */
	#define UART_FCRVAL (UART_FCR_FIFO_EN \| \
	UART_FCR_RXSR \| \
	UART_FCR_TXSR) /* Clear & enable FIFOs */

	#ifndef CONFIG_DM_SERIAL
	#ifdef CONFIG_SYS_NS16550_PORT_MAPPED
	#define serial_out(x, y) outb(x, (ulong)y)
	#define serial_in(y) inb((ulong)y)
	#elif defined(CONFIG_SYS_NS16550_MEM32) && (CONFIG_SYS_NS16550_REG_SIZE > 0)
	#define serial_out(x, y) out_be32(y, x)
	#define serial_in(y) in_be32(y)
	#elif defined(CONFIG_SYS_NS16550_MEM32) && (CONFIG_SYS_NS16550_REG_SIZE < 0)
	#define serial_out(x, y) out_le32(y, x)
	#define serial_in(y) in_le32(y)
	#else
	#define serial_out(x, y) writeb(x, y)
	#define serial_in(y) readb(y)
	#endif
	#endif /* !CONFIG_DM_SERIAL */

	#if defined(CONFIG_SOC_KEYSTONE)
	#define UART_REG_VAL_PWREMU_MGMT_UART_DISABLE 0
	#define UART_REG_VAL_PWREMU_MGMT_UART_ENABLE ((1 << 14) \| (1 << 13) \| (1 << 0))
	#undef UART_MCRVAL
	#ifdef CONFIG_SERIAL_HW_FLOW_CONTROL
	#define UART_MCRVAL (UART_MCR_RTS \| UART_MCR_AFE)
	#else
	#define UART_MCRVAL (UART_MCR_RTS)
	#endif
	#endif

	#ifndef CONFIG_SYS_NS16550_IER
	#define CONFIG_SYS_NS16550_IER 0x00
	#endif /* CONFIG_SYS_NS16550_IER */

	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_BIG_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_BIG_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
	}

	#ifdef CONFIG_DM_SERIAL

	#ifndef CONFIG_SYS_NS16550_CLK
	#define CONFIG_SYS_NS16550_CLK 0
	#endif

	static void ns16550_writeb(NS16550_t port, int offset, int value)
	{
	struct ns16550_platdata *plat = port->plat;
	unsigned char *addr;

	offset *= 1 << plat->reg_shift;
	addr = (unsigned char *)plat->base + offset;

	/*
	* As far as we know it doesn't make sense to support selection of
	* these options at run-time, so use the existing CONFIG options.
	*/
	serial_out_shift(addr + plat->reg_offset, plat->reg_shift, value);
	}

	static int ns16550_readb(NS16550_t port, int offset)
	{
	struct ns16550_platdata *plat = port->plat;
	unsigned char *addr;

	offset *= 1 << plat->reg_shift;
	addr = (unsigned char *)plat->base + offset;

	return serial_in_shift(addr + plat->reg_offset, plat->reg_shift);
	}

	/* We can clean these up once everything is moved to driver model */
	#define serial_out(value, addr) \
	ns16550_writeb(com_port, \
	(unsigned char )addr - (unsigned char )com_port, value)
	#define serial_in(addr) \
	ns16550_readb(com_port, \
	(unsigned char )addr - (unsigned char )com_port)
	#endif

	int ns16550_calc_divisor(NS16550_t port, int clock, int baudrate)
	{
	const unsigned int mode_x_div = 16;

	return DIV_ROUND_CLOSEST(clock, mode_x_div * baudrate);
	}

	static void NS16550_setbrg(NS16550_t com_port, int baud_divisor)
	{
	serial_out(UART_LCR_BKSE \| UART_LCRVAL, &com_port->lcr);
	serial_out(baud_divisor & 0xff, &com_port->dll);
	serial_out((baud_divisor >> 8) & 0xff, &com_port->dlm);
	serial_out(UART_LCRVAL, &com_port->lcr);
	}

	void NS16550_init(NS16550_t com_port, int baud_divisor)
	{
	#if (defined(CONFIG_SPL_BUILD) && \
	(defined(CONFIG_OMAP34XX) \|\| defined(CONFIG_OMAP44XX)))
	/*
	* On some OMAP3/OMAP4 devices when UART3 is configured for boot mode
	* before SPL starts only THRE bit is set. We have to empty the
	* transmitter before initialization starts.
	*/
	if ((serial_in(&com_port->lsr) & (UART_LSR_TEMT \| UART_LSR_THRE))
	== UART_LSR_THRE) {
	if (baud_divisor != -1)
	NS16550_setbrg(com_port, baud_divisor);
	serial_out(0, &com_port->mdr1);
	}
	#endif

	while (!(serial_in(&com_port->lsr) & UART_LSR_TEMT))
	;

	serial_out(CONFIG_SYS_NS16550_IER, &com_port->ier);
	#if defined(CONFIG_OMAP) \|\| defined(CONFIG_AM33XX) \|\| \
	defined(CONFIG_TI81XX) \|\| defined(CONFIG_AM43XX)
	serial_out(0x7, &com_port->mdr1); /* mode select reset TL16C750*/
	#endif
	serial_out(UART_MCRVAL, &com_port->mcr);
	serial_out(UART_FCRVAL, &com_port->fcr);
	if (baud_divisor != -1)
	NS16550_setbrg(com_port, baud_divisor);
	#if defined(CONFIG_OMAP) \|\| \
	defined(CONFIG_AM33XX) \|\| defined(CONFIG_SOC_DA8XX) \|\| \
	defined(CONFIG_TI81XX) \|\| defined(CONFIG_AM43XX)

	/* /16 is proper to hit 115200 with 48MHz */
	serial_out(0, &com_port->mdr1);
	#endif /* CONFIG_OMAP */
	#if defined(CONFIG_SOC_KEYSTONE)
	serial_out(UART_REG_VAL_PWREMU_MGMT_UART_ENABLE, &com_port->regC);
	#endif
	}

	#ifndef CONFIG_NS16550_MIN_FUNCTIONS
	void NS16550_reinit(NS16550_t com_port, int baud_divisor)
	{
	serial_out(CONFIG_SYS_NS16550_IER, &com_port->ier);
	NS16550_setbrg(com_port, 0);
	serial_out(UART_MCRVAL, &com_port->mcr);
	serial_out(UART_FCRVAL, &com_port->fcr);
	NS16550_setbrg(com_port, baud_divisor);
	}
	#endif /* CONFIG_NS16550_MIN_FUNCTIONS */

	void NS16550_putc(NS16550_t com_port, char c)
	{
	while ((serial_in(&com_port->lsr) & UART_LSR_THRE) == 0)
	;
	serial_out(c, &com_port->thr);

	/*
	* Call watchdog_reset() upon newline. This is done here in putc
	* since the environment code uses a single puts() to print the complete
	* environment upon "printenv". So we can't put this watchdog call
	* in puts().
	*/
	if (c == '\n')
	WATCHDOG_RESET();
	}

	#ifndef CONFIG_NS16550_MIN_FUNCTIONS
	char NS16550_getc(NS16550_t com_port)
	{
	while ((serial_in(&com_port->lsr) & UART_LSR_DR) == 0) {
	#if !defined(CONFIG_SPL_BUILD) && defined(CONFIG_USB_TTY)
	extern void usbtty_poll(void);
	usbtty_poll();
	#endif
	WATCHDOG_RESET();
	}
	return serial_in(&com_port->rbr);
	}

	int NS16550_tstc(NS16550_t com_port)
	{
	return (serial_in(&com_port->lsr) & UART_LSR_DR) != 0;
	}

	#endif /* CONFIG_NS16550_MIN_FUNCTIONS */

	#ifdef CONFIG_DEBUG_UART_NS16550

	#include <debug_uart.h>

	#define serial_dout(reg, value) \
	serial_out_shift((char *)com_port + \
	((char )reg - (char )com_port) * \
	(1 << CONFIG_DEBUG_UART_SHIFT), \
	CONFIG_DEBUG_UART_SHIFT, value)
	#define serial_din(reg) \
	serial_in_shift((char *)com_port + \
	((char )reg - (char )com_port) * \
	(1 << CONFIG_DEBUG_UART_SHIFT), \
	CONFIG_DEBUG_UART_SHIFT)

	static inline void _debug_uart_init(void)
	{
	struct NS16550 com_port = (struct NS16550 )CONFIG_DEBUG_UART_BASE;
	int baud_divisor;

	/*
	* We copy the code from above because it is already horribly messy.
	* Trying to refactor to nicely remove the duplication doesn't seem
	* feasible. The better fix is to move all users of this driver to
	* driver model.
	*/
	baud_divisor = ns16550_calc_divisor(com_port, CONFIG_DEBUG_UART_CLOCK,
	CONFIG_BAUDRATE);
	serial_dout(&com_port->ier, CONFIG_SYS_NS16550_IER);
	serial_dout(&com_port->mcr, UART_MCRVAL);
	serial_dout(&com_port->fcr, UART_FCRVAL);

	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);
	}

	static inline void _debug_uart_putc(int ch)
	{
	struct NS16550 com_port = (struct NS16550 )CONFIG_DEBUG_UART_BASE;

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

	DEBUG_UART_FUNCS

	#endif

	#ifdef CONFIG_DM_SERIAL
	static int ns16550_serial_putc(struct udevice *dev, const char ch)
	{
	struct NS16550 *const com_port = dev_get_priv(dev);

	if (!(serial_in(&com_port->lsr) & UART_LSR_THRE))
	return -EAGAIN;
	serial_out(ch, &com_port->thr);

	/*
	* Call watchdog_reset() upon newline. This is done here in putc
	* since the environment code uses a single puts() to print the complete
	* environment upon "printenv". So we can't put this watchdog call
	* in puts().
	*/
	if (ch == '\n')
	WATCHDOG_RESET();

	return 0;
	}

	static int ns16550_serial_pending(struct udevice *dev, bool input)
	{
	struct NS16550 *const com_port = dev_get_priv(dev);

	if (input)
	return serial_in(&com_port->lsr) & UART_LSR_DR ? 1 : 0;
	else
	return serial_in(&com_port->lsr) & UART_LSR_THRE ? 0 : 1;
	}

	static int ns16550_serial_getc(struct udevice *dev)
	{
	struct NS16550 *const com_port = dev_get_priv(dev);

	if (!(serial_in(&com_port->lsr) & UART_LSR_DR))
	return -EAGAIN;

	return serial_in(&com_port->rbr);
	}

	static int ns16550_serial_setbrg(struct udevice *dev, int baudrate)
	{
	struct NS16550 *const com_port = dev_get_priv(dev);
	struct ns16550_platdata *plat = com_port->plat;
	int clock_divisor;

	clock_divisor = ns16550_calc_divisor(com_port, plat->clock, baudrate);

	NS16550_setbrg(com_port, clock_divisor);

	return 0;
	}

	int ns16550_serial_probe(struct udevice *dev)
	{
	struct NS16550 *const com_port = dev_get_priv(dev);

	com_port->plat = dev_get_platdata(dev);
	NS16550_init(com_port, -1);

	return 0;
	}

	#if CONFIG_IS_ENABLED(OF_CONTROL) && !CONFIG_IS_ENABLED(OF_PLATDATA)
	int ns16550_serial_ofdata_to_platdata(struct udevice *dev)
	{
	struct ns16550_platdata *plat = dev->platdata;
	fdt_addr_t addr;
	struct clk clk;
	int err;

	/* try Processor Local Bus device first */
	addr = dev_get_addr(dev);
	#if defined(CONFIG_PCI) && defined(CONFIG_DM_PCI)
	if (addr == FDT_ADDR_T_NONE) {
	/* then try pci device */
	struct fdt_pci_addr pci_addr;
	u32 bar;
	int ret;

	/* we prefer to use a memory-mapped register */
	ret = fdtdec_get_pci_addr(gd->fdt_blob, dev->of_offset,
	FDT_PCI_SPACE_MEM32, "reg",
	&pci_addr);
	if (ret) {
	/* try if there is any i/o-mapped register */
	ret = fdtdec_get_pci_addr(gd->fdt_blob,
	dev->of_offset,
	FDT_PCI_SPACE_IO,
	"reg", &pci_addr);
	if (ret)
	return ret;
	}

	ret = fdtdec_get_pci_bar32(dev, &pci_addr, &bar);
	if (ret)
	return ret;

	addr = bar;
	}
	#endif

	if (addr == FDT_ADDR_T_NONE)
	return -EINVAL;

	#ifdef CONFIG_SYS_NS16550_PORT_MAPPED
	plat->base = addr;
	#else
	plat->base = (unsigned long)map_physmem(addr, 0, MAP_NOCACHE);
	#endif

	plat->reg_offset = fdtdec_get_int(gd->fdt_blob, dev->of_offset,
	"reg-offset", 0);
	plat->reg_shift = fdtdec_get_int(gd->fdt_blob, dev->of_offset,
	"reg-shift", 0);

	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 != -ENODEV && err != -ENOSYS) {
	debug("ns16550 failed to get clock\n");
	return err;
	}

	if (!plat->clock)
	plat->clock = fdtdec_get_int(gd->fdt_blob, dev->of_offset,
	"clock-frequency",
	CONFIG_SYS_NS16550_CLK);
	if (!plat->clock) {
	debug("ns16550 clock not defined\n");
	return -EINVAL;
	}

	return 0;
	}
	#endif

	const struct dm_serial_ops ns16550_serial_ops = {
	.putc = ns16550_serial_putc,
	.pending = ns16550_serial_pending,
	.getc = ns16550_serial_getc,
	.setbrg = ns16550_serial_setbrg,
	};

	#if !CONFIG_IS_ENABLED(OF_PLATDATA)
	#if CONFIG_IS_ENABLED(OF_CONTROL)
	/*
	* Please consider existing compatible strings before adding a new
	* one to keep this table compact. Or you may add a generic "ns16550"
	* compatible string to your dts.
	*/
	static const struct udevice_id ns16550_serial_ids[] = {
	{ .compatible = "ns16550" },
	{ .compatible = "ns16550a" },
	{ .compatible = "nvidia,tegra20-uart" },
	{ .compatible = "snps,dw-apb-uart" },
	{ .compatible = "ti,omap2-uart" },
	{ .compatible = "ti,omap3-uart" },
	{ .compatible = "ti,omap4-uart" },
	{ .compatible = "ti,am3352-uart" },
	{ .compatible = "ti,am4372-uart" },
	{ .compatible = "ti,dra742-uart" },
	{}
	};
	#endif

	#if CONFIG_IS_ENABLED(SERIAL_PRESENT)
	U_BOOT_DRIVER(ns16550_serial) = {
	.name = "ns16550_serial",
	.id = UCLASS_SERIAL,
	#if CONFIG_IS_ENABLED(OF_CONTROL)
	.of_match = ns16550_serial_ids,
	.ofdata_to_platdata = ns16550_serial_ofdata_to_platdata,
	.platdata_auto_alloc_size = sizeof(struct ns16550_platdata),
	#endif
	.priv_auto_alloc_size = sizeof(struct NS16550),
	.probe = ns16550_serial_probe,
	.ops = &ns16550_serial_ops,
	.flags = DM_FLAG_PRE_RELOC,
	};
	#endif
	#endif /* !OF_PLATDATA */
	#endif /* CONFIG_DM_SERIAL */