drivers/serial/serial_lpuart.c - uboot-imx - Git at Google

 /*
  * Copyright 2013 Freescale Semiconductor, Inc.
  *
  * SPDX-License-Identifier:	GPL-2.0+
  */

 #include <common.h>
 #include <dm.h>
 #include <fsl_lpuart.h>
 #include <watchdog.h>
 #include <asm/io.h>
 #include <serial.h>
 #include <linux/compiler.h>
 #include <asm/arch/imx-regs.h>
 #include <asm/arch/clock.h>

 #define US1_TDRE	(1 << 7)
 #define US1_RDRF	(1 << 5)
 #define US1_OR		(1 << 3)
 #define UC2_TE		(1 << 3)
 #define UC2_RE		(1 << 2)
 #define CFIFO_TXFLUSH	(1 << 7)
 #define CFIFO_RXFLUSH	(1 << 6)
 #define SFIFO_RXOF	(1 << 2)
 #define SFIFO_RXUF	(1 << 0)

 #define STAT_LBKDIF	(1 << 31)
 #define STAT_RXEDGIF	(1 << 30)
 #define STAT_TDRE	(1 << 23)
 #define STAT_RDRF	(1 << 21)
 #define STAT_IDLE	(1 << 20)
 #define STAT_OR		(1 << 19)
 #define STAT_NF		(1 << 18)
 #define STAT_FE		(1 << 17)
 #define STAT_PF		(1 << 16)
 #define STAT_MA1F	(1 << 15)
 #define STAT_MA2F	(1 << 14)
 #define STAT_FLAGS	(STAT_LBKDIF | STAT_RXEDGIF | STAT_IDLE | STAT_OR | \
 			 STAT_NF | STAT_FE | STAT_PF | STAT_MA1F | STAT_MA2F)

 #define CTRL_TE		(1 << 19)
 #define CTRL_RE		(1 << 18)

 #define FIFO_RXFLUSH		(1 << 14)
 #define FIFO_TXFLUSH		(1 << 15)
 #define FIFO_TXSIZE_MASK 	0x70
 #define FIFO_TXSIZE_OFF 	4
 #define FIFO_RXSIZE_MASK 	0x7
 #define FIFO_RXSIZE_OFF 	0
 #define FIFO_TXFE		0x80
 #define FIFO_RXFE		0x08

 #define WATER_TXWATER_OFF	0
 #define WATER_RXWATER_OFF	16

 DECLARE_GLOBAL_DATA_PTR;

 #define LPUART_FLAG_REGMAP_32BIT_REG	BIT(0)
 #define LPUART_FLAG_REGMAP_ENDIAN_BIG	BIT(1)

 enum lpuart_devtype {
 	DEV_VF610 = 1,
 	DEV_LS1021A,
 	DEV_MX7ULP,
 	DEV_IMX8
 };

 struct lpuart_serial_platdata {
 	void *reg;
 	enum lpuart_devtype devtype;
 	ulong flags;
 };

 static void lpuart_read32(u32 flags, u32 *addr, u32 *val)
 {
 	if (flags & LPUART_FLAG_REGMAP_32BIT_REG) {
 		if (flags & LPUART_FLAG_REGMAP_ENDIAN_BIG)
 			*(u32 *)val = in_be32(addr);
 		else
 			*(u32 *)val = in_le32(addr);
 	}
 }

 static void lpuart_write32(u32 flags, u32 *addr, u32 val)
 {
 	if (flags & LPUART_FLAG_REGMAP_32BIT_REG) {
 		if (flags & LPUART_FLAG_REGMAP_ENDIAN_BIG)
 			out_be32(addr, val);
 		else
 			out_le32(addr, val);
 	}
 }


 #ifndef CONFIG_SYS_CLK_FREQ
 #define CONFIG_SYS_CLK_FREQ	0
 #endif

 u32 __weak get_lpuart_clk(void)
 {
 	return CONFIG_SYS_CLK_FREQ;
 }

 static bool is_lpuart32(struct udevice *dev)
 {
 	struct lpuart_serial_platdata *plat = dev->platdata;

 	return plat->flags & LPUART_FLAG_REGMAP_32BIT_REG;
 }

 static void _lpuart_serial_setbrg(struct lpuart_serial_platdata *plat,
 				  int baudrate)
 {
 	struct lpuart_fsl *base = plat->reg;
 	u32 clk = get_lpuart_clk();
 	u16 sbr;

 	sbr = (u16)(clk / (16 * baudrate));

 	/* place adjustment later - n/32 BRFA */
 	__raw_writeb(sbr >> 8, &base->ubdh);
 	__raw_writeb(sbr & 0xff, &base->ubdl);
 }

 static int _lpuart_serial_getc(struct lpuart_serial_platdata *plat)
 {
 	struct lpuart_fsl *base = plat->reg;
 	while (!(__raw_readb(&base->us1) & (US1_RDRF | US1_OR)))
 		WATCHDOG_RESET();

 	barrier();

 	return __raw_readb(&base->ud);
 }

 static void _lpuart_serial_putc(struct lpuart_serial_platdata *plat,
 				const char c)
 {
 	struct lpuart_fsl *base = plat->reg;

 	while (!(__raw_readb(&base->us1) & US1_TDRE))
 		WATCHDOG_RESET();

 	__raw_writeb(c, &base->ud);
 }

 /* Test whether a character is in the RX buffer */
 static int _lpuart_serial_tstc(struct lpuart_serial_platdata *plat)
 {
 	struct lpuart_fsl *base = plat->reg;

 	if (__raw_readb(&base->urcfifo) == 0)
 		return 0;

 	return 1;
 }

 /*
  * Initialise the serial port with the given baudrate. The settings
  * are always 8 data bits, no parity, 1 stop bit, no start bits.
  */
 static int _lpuart_serial_init(struct lpuart_serial_platdata *plat)
 {
 	struct lpuart_fsl *base = (struct lpuart_fsl *)plat->reg;
 	u8 ctrl;

 	ctrl = __raw_readb(&base->uc2);
 	ctrl &= ~UC2_RE;
 	ctrl &= ~UC2_TE;
 	__raw_writeb(ctrl, &base->uc2);

 	__raw_writeb(0, &base->umodem);
 	__raw_writeb(0, &base->uc1);

 	/* Disable FIFO and flush buffer */
 	__raw_writeb(0x0, &base->upfifo);
 	__raw_writeb(0x0, &base->utwfifo);
 	__raw_writeb(0x1, &base->urwfifo);
 	__raw_writeb(CFIFO_TXFLUSH | CFIFO_RXFLUSH, &base->ucfifo);

 	/* provide data bits, parity, stop bit, etc */
 	_lpuart_serial_setbrg(plat, gd->baudrate);

 	__raw_writeb(UC2_RE | UC2_TE, &base->uc2);

 	return 0;
 }

 static void _lpuart32_serial_setbrg_7ulp(struct lpuart_serial_platdata *plat,
 					 int baudrate)
 {
 	struct lpuart_fsl_reg32 *base = plat->reg;
 	u32 sbr, osr, baud_diff, tmp_osr, tmp_sbr, tmp_diff, tmp;
 	u32 clk = get_lpuart_clk();

 	baud_diff = baudrate;
 	osr = 0;
 	sbr = 0;

 	for (tmp_osr = 4; tmp_osr <= 32; tmp_osr++) {
 		tmp_sbr = (clk / (baudrate * tmp_osr));

 		if (tmp_sbr == 0)
 			tmp_sbr = 1;

 		/*calculate difference in actual buad w/ current values */
 		tmp_diff = (clk / (tmp_osr * tmp_sbr));
 		tmp_diff = tmp_diff - baudrate;

 		/* select best values between sbr and sbr+1 */
 		if (tmp_diff > (baudrate - (clk / (tmp_osr * (tmp_sbr + 1))))) {
 			tmp_diff = baudrate - (clk / (tmp_osr * (tmp_sbr + 1)));
 			tmp_sbr++;
 		}

 		if (tmp_diff <= baud_diff) {
 			baud_diff = tmp_diff;
 			osr = tmp_osr;
 			sbr = tmp_sbr;
 		}
 	}

 	/*
 	 * TODO: handle buadrate outside acceptable rate
 	 * if (baudDiff > ((config->baudRate_Bps / 100) * 3))
 	 * {
 	 *   Unacceptable baud rate difference of more than 3%
 	 *   return kStatus_LPUART_BaudrateNotSupport;
 	 * }
 	 */
 	tmp = in_le32(&base->baud);

 	if ((osr > 3) && (osr < 8))
 		tmp |= LPUART_BAUD_BOTHEDGE_MASK;

 	tmp &= ~LPUART_BAUD_OSR_MASK;
 	tmp |= LPUART_BAUD_OSR(osr-1);

 	tmp &= ~LPUART_BAUD_SBR_MASK;
 	tmp |= LPUART_BAUD_SBR(sbr);

 	/* explicitly disable 10 bit mode & set 1 stop bit */
 	tmp &= ~(LPUART_BAUD_M10_MASK | LPUART_BAUD_SBNS_MASK);

 	out_le32(&base->baud, tmp);
 }

 static void _lpuart32_serial_setbrg(struct lpuart_serial_platdata *plat,
 				    int baudrate)
 {
 	struct lpuart_fsl_reg32 *base = plat->reg;
 	u32 clk = get_lpuart_clk();
 	u32 sbr;

 	sbr = (clk / (16 * baudrate));

 	/* place adjustment later - n/32 BRFA */
 	lpuart_write32(plat->flags, &base->baud, sbr);
 }

 static int _lpuart32_serial_getc(struct lpuart_serial_platdata *plat)
 {
 	struct lpuart_fsl_reg32 *base = plat->reg;
 	u32 stat, val;

 	lpuart_read32(plat->flags, &base->stat, &stat);
 	while ((stat & STAT_RDRF) == 0) {
 		lpuart_write32(plat->flags, &base->stat, STAT_FLAGS);
 		WATCHDOG_RESET();
 		lpuart_read32(plat->flags, &base->stat, &stat);
 	}

 	lpuart_read32(plat->flags, &base->data, &val);

 	if (plat->devtype == DEV_MX7ULP || plat->devtype == DEV_IMX8) {
 		lpuart_read32(plat->flags, &base->stat, &stat);
 		if (stat & STAT_OR)
 			lpuart_write32(plat->flags, &base->stat, STAT_OR);
 	}

 	return val & 0x3ff;
 }

 static void _lpuart32_serial_putc(struct lpuart_serial_platdata *plat,
 				  const char c)
 {
 	struct lpuart_fsl_reg32 *base = plat->reg;
 	u32 stat;

 	if (plat->devtype == DEV_MX7ULP || plat->devtype == DEV_IMX8) {
 		if (c == '\n')
 			serial_putc('\r');
 	}

 	while (true) {
 		lpuart_read32(plat->flags, &base->stat, &stat);

 		if ((stat & STAT_TDRE))
 			break;

 		WATCHDOG_RESET();
 	}

 	lpuart_write32(plat->flags, &base->data, c);
 }

 /* Test whether a character is in the RX buffer */
 static int _lpuart32_serial_tstc(struct lpuart_serial_platdata *plat)
 {
 	struct lpuart_fsl_reg32 *base = plat->reg;
 	u32 water;

 	lpuart_read32(plat->flags, &base->water, &water);

 	if ((water >> 24) == 0)
 		return 0;

 	return 1;
 }

 /*
  * Initialise the serial port with the given baudrate. The settings
  * are always 8 data bits, no parity, 1 stop bit, no start bits.
  */
 static int _lpuart32_serial_init(struct lpuart_serial_platdata *plat)
 {
 	struct lpuart_fsl_reg32 *base = (struct lpuart_fsl_reg32 *)plat->reg;
 	u32 val, tx_fifo_size;

 	lpuart_read32(plat->flags, &base->ctrl, &val);
 	val &= ~CTRL_RE;
 	val &= ~CTRL_TE;
 	lpuart_write32(plat->flags, &base->ctrl, val);

 	lpuart_write32(plat->flags, &base->modir, 0);

 	lpuart_read32(plat->flags, &base->fifo, &val);
 	tx_fifo_size = (val & FIFO_TXSIZE_MASK) >> FIFO_TXSIZE_OFF;
 	if (tx_fifo_size > 1)
 		tx_fifo_size = tx_fifo_size >> 1; /* Set the TX water to half of FIFO size */

 	/* Set RX water to 0, to be triggered by any receive data */
 	lpuart_write32(plat->flags, &base->water, (tx_fifo_size << WATER_TXWATER_OFF));

 	val |= (FIFO_TXFE | FIFO_RXFE | FIFO_TXFLUSH | FIFO_RXFLUSH); /* Enable TX and RX FIFO */
 	lpuart_write32(plat->flags, &base->fifo, val);

 	lpuart_write32(plat->flags, &base->match, 0);

 	if (plat->devtype == DEV_MX7ULP || plat->devtype == DEV_IMX8) {
 		_lpuart32_serial_setbrg_7ulp(plat, gd->baudrate);
 	} else {
 		/* provide data bits, parity, stop bit, etc */
 		_lpuart32_serial_setbrg(plat, gd->baudrate);
 	}

 	lpuart_write32(plat->flags, &base->ctrl, CTRL_RE | CTRL_TE);

 	return 0;
 }

 static int lpuart_serial_setbrg(struct udevice *dev, int baudrate)
 {
 	struct lpuart_serial_platdata *plat = dev->platdata;

 	if (is_lpuart32(dev)) {
 		if (plat->devtype == DEV_MX7ULP || plat->devtype == DEV_IMX8)
 			_lpuart32_serial_setbrg_7ulp(plat, baudrate);
 		else
 			_lpuart32_serial_setbrg(plat, baudrate);
 	} else {
 		_lpuart_serial_setbrg(plat, baudrate);
 	}

 	return 0;
 }

 static int lpuart_serial_getc(struct udevice *dev)
 {
 	struct lpuart_serial_platdata *plat = dev->platdata;

 	if (is_lpuart32(dev))
 		return _lpuart32_serial_getc(plat);

 	return _lpuart_serial_getc(plat);
 }

 static int lpuart_serial_putc(struct udevice *dev, const char c)
 {
 	struct lpuart_serial_platdata *plat = dev->platdata;

 	if (is_lpuart32(dev))
 		_lpuart32_serial_putc(plat, c);
 	else
 		_lpuart_serial_putc(plat, c);

 	return 0;
 }

 static int lpuart_serial_pending(struct udevice *dev, bool input)
 {
 	struct lpuart_serial_platdata *plat = dev->platdata;
 	struct lpuart_fsl *reg = plat->reg;
 	struct lpuart_fsl_reg32 *reg32 = plat->reg;
 	u32 stat;

 	if (is_lpuart32(dev)) {
 		if (input) {
 			return _lpuart32_serial_tstc(plat);
 		} else {
 			lpuart_read32(plat->flags, &reg32->stat, &stat);
 			return stat & STAT_TDRE ? 0 : 1;
 		}
 	}

 	if (input)
 		return _lpuart_serial_tstc(plat);
 	else
 		return __raw_readb(&reg->us1) & US1_TDRE ? 0 : 1;
 }

 static int lpuart_serial_probe(struct udevice *dev)
 {
 	struct lpuart_serial_platdata *plat = dev->platdata;

 	if (is_lpuart32(dev))
 		return _lpuart32_serial_init(plat);
 	else
 		return _lpuart_serial_init(plat);
 }

 static int lpuart_serial_ofdata_to_platdata(struct udevice *dev)
 {
 	struct lpuart_serial_platdata *plat = dev->platdata;
 	const void *blob = gd->fdt_blob;
 	int node = dev->of_offset;
 	fdt_addr_t addr;

 	addr = dev_get_addr(dev);
 	if (addr == FDT_ADDR_T_NONE)
 		return -EINVAL;

 	plat->reg = (void *)addr;
 	plat->flags = dev_get_driver_data(dev);

 	if (!fdt_node_check_compatible(blob, node, "fsl,ls1021a-lpuart"))
 		plat->devtype = DEV_LS1021A;
 	else if (!fdt_node_check_compatible(blob, node, "fsl,imx7ulp-lpuart"))
 		plat->devtype = DEV_MX7ULP;
 	else if (!fdt_node_check_compatible(blob, node, "fsl,vf610-lpuart"))
 		plat->devtype = DEV_VF610;
 	else if (!fdt_node_check_compatible(blob, node, "fsl,imx8qm-lpuart"))
 		plat->devtype = DEV_IMX8;

 	return 0;
 }

 static const struct dm_serial_ops lpuart_serial_ops = {
 	.putc = lpuart_serial_putc,
 	.pending = lpuart_serial_pending,
 	.getc = lpuart_serial_getc,
 	.setbrg = lpuart_serial_setbrg,
 };

 static const struct udevice_id lpuart_serial_ids[] = {
 	{ .compatible = "fsl,ls1021a-lpuart", .data =
 		LPUART_FLAG_REGMAP_32BIT_REG | LPUART_FLAG_REGMAP_ENDIAN_BIG },
 	{ .compatible = "fsl,imx7ulp-lpuart",
 		.data = LPUART_FLAG_REGMAP_32BIT_REG },
 	{ .compatible = "fsl,vf610-lpuart"},
 	{ .compatible = "fsl,imx8qm-lpuart",
 		.data = LPUART_FLAG_REGMAP_32BIT_REG },
 	{ }
 };

 U_BOOT_DRIVER(serial_lpuart) = {
 	.name	= "serial_lpuart",
 	.id	= UCLASS_SERIAL,
 	.of_match = lpuart_serial_ids,
 	.ofdata_to_platdata = lpuart_serial_ofdata_to_platdata,
 	.platdata_auto_alloc_size = sizeof(struct lpuart_serial_platdata),
 	.probe = lpuart_serial_probe,
 	.ops	= &lpuart_serial_ops,
 	.flags = DM_FLAG_PRE_RELOC,
 };
	/*
	* Copyright 2013 Freescale Semiconductor, Inc.
	*
	* SPDX-License-Identifier: GPL-2.0+
	*/

	#include <common.h>
	#include <dm.h>
	#include <fsl_lpuart.h>
	#include <watchdog.h>
	#include <asm/io.h>
	#include <serial.h>
	#include <linux/compiler.h>
	#include <asm/arch/imx-regs.h>
	#include <asm/arch/clock.h>

	#define US1_TDRE (1 << 7)
	#define US1_RDRF (1 << 5)
	#define US1_OR (1 << 3)
	#define UC2_TE (1 << 3)
	#define UC2_RE (1 << 2)
	#define CFIFO_TXFLUSH (1 << 7)
	#define CFIFO_RXFLUSH (1 << 6)
	#define SFIFO_RXOF (1 << 2)
	#define SFIFO_RXUF (1 << 0)

	#define STAT_LBKDIF (1 << 31)
	#define STAT_RXEDGIF (1 << 30)
	#define STAT_TDRE (1 << 23)
	#define STAT_RDRF (1 << 21)
	#define STAT_IDLE (1 << 20)
	#define STAT_OR (1 << 19)
	#define STAT_NF (1 << 18)
	#define STAT_FE (1 << 17)
	#define STAT_PF (1 << 16)
	#define STAT_MA1F (1 << 15)
	#define STAT_MA2F (1 << 14)
	#define STAT_FLAGS (STAT_LBKDIF \| STAT_RXEDGIF \| STAT_IDLE \| STAT_OR \| \
	STAT_NF \| STAT_FE \| STAT_PF \| STAT_MA1F \| STAT_MA2F)

	#define CTRL_TE (1 << 19)
	#define CTRL_RE (1 << 18)

	#define FIFO_RXFLUSH (1 << 14)
	#define FIFO_TXFLUSH (1 << 15)
	#define FIFO_TXSIZE_MASK 0x70
	#define FIFO_TXSIZE_OFF 4
	#define FIFO_RXSIZE_MASK 0x7
	#define FIFO_RXSIZE_OFF 0
	#define FIFO_TXFE 0x80
	#define FIFO_RXFE 0x08

	#define WATER_TXWATER_OFF 0
	#define WATER_RXWATER_OFF 16

	DECLARE_GLOBAL_DATA_PTR;

	#define LPUART_FLAG_REGMAP_32BIT_REG BIT(0)
	#define LPUART_FLAG_REGMAP_ENDIAN_BIG BIT(1)

	enum lpuart_devtype {
	DEV_VF610 = 1,
	DEV_LS1021A,
	DEV_MX7ULP,
	DEV_IMX8
	};

	struct lpuart_serial_platdata {
	void *reg;
	enum lpuart_devtype devtype;
	ulong flags;
	};

	static void lpuart_read32(u32 flags, u32 addr, u32 val)
	{
	if (flags & LPUART_FLAG_REGMAP_32BIT_REG) {
	if (flags & LPUART_FLAG_REGMAP_ENDIAN_BIG)
	(u32 )val = in_be32(addr);
	else
	(u32 )val = in_le32(addr);
	}
	}

	static void lpuart_write32(u32 flags, u32 *addr, u32 val)
	{
	if (flags & LPUART_FLAG_REGMAP_32BIT_REG) {
	if (flags & LPUART_FLAG_REGMAP_ENDIAN_BIG)
	out_be32(addr, val);
	else
	out_le32(addr, val);
	}
	}


	#ifndef CONFIG_SYS_CLK_FREQ
	#define CONFIG_SYS_CLK_FREQ 0
	#endif

	u32 __weak get_lpuart_clk(void)
	{
	return CONFIG_SYS_CLK_FREQ;
	}

	static bool is_lpuart32(struct udevice *dev)
	{
	struct lpuart_serial_platdata *plat = dev->platdata;

	return plat->flags & LPUART_FLAG_REGMAP_32BIT_REG;
	}

	static void _lpuart_serial_setbrg(struct lpuart_serial_platdata *plat,
	int baudrate)
	{
	struct lpuart_fsl *base = plat->reg;
	u32 clk = get_lpuart_clk();
	u16 sbr;

	sbr = (u16)(clk / (16 * baudrate));

	/* place adjustment later - n/32 BRFA */
	__raw_writeb(sbr >> 8, &base->ubdh);
	__raw_writeb(sbr & 0xff, &base->ubdl);
	}

	static int _lpuart_serial_getc(struct lpuart_serial_platdata *plat)
	{
	struct lpuart_fsl *base = plat->reg;
	while (!(__raw_readb(&base->us1) & (US1_RDRF \| US1_OR)))
	WATCHDOG_RESET();

	barrier();

	return __raw_readb(&base->ud);
	}

	static void _lpuart_serial_putc(struct lpuart_serial_platdata *plat,
	const char c)
	{
	struct lpuart_fsl *base = plat->reg;

	while (!(__raw_readb(&base->us1) & US1_TDRE))
	WATCHDOG_RESET();

	__raw_writeb(c, &base->ud);
	}

	/* Test whether a character is in the RX buffer */
	static int _lpuart_serial_tstc(struct lpuart_serial_platdata *plat)
	{
	struct lpuart_fsl *base = plat->reg;

	if (__raw_readb(&base->urcfifo) == 0)
	return 0;

	return 1;
	}

	/*
	* Initialise the serial port with the given baudrate. The settings
	* are always 8 data bits, no parity, 1 stop bit, no start bits.
	*/
	static int _lpuart_serial_init(struct lpuart_serial_platdata *plat)
	{
	struct lpuart_fsl base = (struct lpuart_fsl )plat->reg;
	u8 ctrl;

	ctrl = __raw_readb(&base->uc2);
	ctrl &= ~UC2_RE;
	ctrl &= ~UC2_TE;
	__raw_writeb(ctrl, &base->uc2);

	__raw_writeb(0, &base->umodem);
	__raw_writeb(0, &base->uc1);

	/* Disable FIFO and flush buffer */
	__raw_writeb(0x0, &base->upfifo);
	__raw_writeb(0x0, &base->utwfifo);
	__raw_writeb(0x1, &base->urwfifo);
	__raw_writeb(CFIFO_TXFLUSH \| CFIFO_RXFLUSH, &base->ucfifo);

	/* provide data bits, parity, stop bit, etc */
	_lpuart_serial_setbrg(plat, gd->baudrate);

	__raw_writeb(UC2_RE \| UC2_TE, &base->uc2);

	return 0;
	}

	static void _lpuart32_serial_setbrg_7ulp(struct lpuart_serial_platdata *plat,
	int baudrate)
	{
	struct lpuart_fsl_reg32 *base = plat->reg;
	u32 sbr, osr, baud_diff, tmp_osr, tmp_sbr, tmp_diff, tmp;
	u32 clk = get_lpuart_clk();

	baud_diff = baudrate;
	osr = 0;
	sbr = 0;

	for (tmp_osr = 4; tmp_osr <= 32; tmp_osr++) {
	tmp_sbr = (clk / (baudrate * tmp_osr));

	if (tmp_sbr == 0)
	tmp_sbr = 1;

	/calculate difference in actual buad w/ current values /
	tmp_diff = (clk / (tmp_osr * tmp_sbr));
	tmp_diff = tmp_diff - baudrate;

	/* select best values between sbr and sbr+1 */
	if (tmp_diff > (baudrate - (clk / (tmp_osr * (tmp_sbr + 1))))) {
	tmp_diff = baudrate - (clk / (tmp_osr * (tmp_sbr + 1)));
	tmp_sbr++;
	}

	if (tmp_diff <= baud_diff) {
	baud_diff = tmp_diff;
	osr = tmp_osr;
	sbr = tmp_sbr;
	}
	}

	/*
	* TODO: handle buadrate outside acceptable rate
	* if (baudDiff > ((config->baudRate_Bps / 100) * 3))
	* {
	* Unacceptable baud rate difference of more than 3%
	* return kStatus_LPUART_BaudrateNotSupport;
	* }
	*/
	tmp = in_le32(&base->baud);

	if ((osr > 3) && (osr < 8))
	tmp \|= LPUART_BAUD_BOTHEDGE_MASK;

	tmp &= ~LPUART_BAUD_OSR_MASK;
	tmp \|= LPUART_BAUD_OSR(osr-1);

	tmp &= ~LPUART_BAUD_SBR_MASK;
	tmp \|= LPUART_BAUD_SBR(sbr);

	/* explicitly disable 10 bit mode & set 1 stop bit */
	tmp &= ~(LPUART_BAUD_M10_MASK \| LPUART_BAUD_SBNS_MASK);

	out_le32(&base->baud, tmp);
	}

	static void _lpuart32_serial_setbrg(struct lpuart_serial_platdata *plat,
	int baudrate)
	{
	struct lpuart_fsl_reg32 *base = plat->reg;
	u32 clk = get_lpuart_clk();
	u32 sbr;

	sbr = (clk / (16 * baudrate));

	/* place adjustment later - n/32 BRFA */
	lpuart_write32(plat->flags, &base->baud, sbr);
	}

	static int _lpuart32_serial_getc(struct lpuart_serial_platdata *plat)
	{
	struct lpuart_fsl_reg32 *base = plat->reg;
	u32 stat, val;

	lpuart_read32(plat->flags, &base->stat, &stat);
	while ((stat & STAT_RDRF) == 0) {
	lpuart_write32(plat->flags, &base->stat, STAT_FLAGS);
	WATCHDOG_RESET();
	lpuart_read32(plat->flags, &base->stat, &stat);
	}

	lpuart_read32(plat->flags, &base->data, &val);

	if (plat->devtype == DEV_MX7ULP \|\| plat->devtype == DEV_IMX8) {
	lpuart_read32(plat->flags, &base->stat, &stat);
	if (stat & STAT_OR)
	lpuart_write32(plat->flags, &base->stat, STAT_OR);
	}

	return val & 0x3ff;
	}

	static void _lpuart32_serial_putc(struct lpuart_serial_platdata *plat,
	const char c)
	{
	struct lpuart_fsl_reg32 *base = plat->reg;
	u32 stat;

	if (plat->devtype == DEV_MX7ULP \|\| plat->devtype == DEV_IMX8) {
	if (c == '\n')
	serial_putc('\r');
	}

	while (true) {
	lpuart_read32(plat->flags, &base->stat, &stat);

	if ((stat & STAT_TDRE))
	break;

	WATCHDOG_RESET();
	}

	lpuart_write32(plat->flags, &base->data, c);
	}

	/* Test whether a character is in the RX buffer */
	static int _lpuart32_serial_tstc(struct lpuart_serial_platdata *plat)
	{
	struct lpuart_fsl_reg32 *base = plat->reg;
	u32 water;

	lpuart_read32(plat->flags, &base->water, &water);

	if ((water >> 24) == 0)
	return 0;

	return 1;
	}

	/*
	* Initialise the serial port with the given baudrate. The settings
	* are always 8 data bits, no parity, 1 stop bit, no start bits.
	*/
	static int _lpuart32_serial_init(struct lpuart_serial_platdata *plat)
	{
	struct lpuart_fsl_reg32 base = (struct lpuart_fsl_reg32 )plat->reg;
	u32 val, tx_fifo_size;

	lpuart_read32(plat->flags, &base->ctrl, &val);
	val &= ~CTRL_RE;
	val &= ~CTRL_TE;
	lpuart_write32(plat->flags, &base->ctrl, val);

	lpuart_write32(plat->flags, &base->modir, 0);

	lpuart_read32(plat->flags, &base->fifo, &val);
	tx_fifo_size = (val & FIFO_TXSIZE_MASK) >> FIFO_TXSIZE_OFF;
	if (tx_fifo_size > 1)
	tx_fifo_size = tx_fifo_size >> 1; /* Set the TX water to half of FIFO size */

	/* Set RX water to 0, to be triggered by any receive data */
	lpuart_write32(plat->flags, &base->water, (tx_fifo_size << WATER_TXWATER_OFF));

	val \|= (FIFO_TXFE \| FIFO_RXFE \| FIFO_TXFLUSH \| FIFO_RXFLUSH); /* Enable TX and RX FIFO */
	lpuart_write32(plat->flags, &base->fifo, val);

	lpuart_write32(plat->flags, &base->match, 0);

	if (plat->devtype == DEV_MX7ULP \|\| plat->devtype == DEV_IMX8) {
	_lpuart32_serial_setbrg_7ulp(plat, gd->baudrate);
	} else {
	/* provide data bits, parity, stop bit, etc */
	_lpuart32_serial_setbrg(plat, gd->baudrate);
	}

	lpuart_write32(plat->flags, &base->ctrl, CTRL_RE \| CTRL_TE);

	return 0;
	}

	static int lpuart_serial_setbrg(struct udevice *dev, int baudrate)
	{
	struct lpuart_serial_platdata *plat = dev->platdata;

	if (is_lpuart32(dev)) {
	if (plat->devtype == DEV_MX7ULP \|\| plat->devtype == DEV_IMX8)
	_lpuart32_serial_setbrg_7ulp(plat, baudrate);
	else
	_lpuart32_serial_setbrg(plat, baudrate);
	} else {
	_lpuart_serial_setbrg(plat, baudrate);
	}

	return 0;
	}

	static int lpuart_serial_getc(struct udevice *dev)
	{
	struct lpuart_serial_platdata *plat = dev->platdata;

	if (is_lpuart32(dev))
	return _lpuart32_serial_getc(plat);

	return _lpuart_serial_getc(plat);
	}

	static int lpuart_serial_putc(struct udevice *dev, const char c)
	{
	struct lpuart_serial_platdata *plat = dev->platdata;

	if (is_lpuart32(dev))
	_lpuart32_serial_putc(plat, c);
	else
	_lpuart_serial_putc(plat, c);

	return 0;
	}

	static int lpuart_serial_pending(struct udevice *dev, bool input)
	{
	struct lpuart_serial_platdata *plat = dev->platdata;
	struct lpuart_fsl *reg = plat->reg;
	struct lpuart_fsl_reg32 *reg32 = plat->reg;
	u32 stat;

	if (is_lpuart32(dev)) {
	if (input) {
	return _lpuart32_serial_tstc(plat);
	} else {
	lpuart_read32(plat->flags, &reg32->stat, &stat);
	return stat & STAT_TDRE ? 0 : 1;
	}
	}

	if (input)
	return _lpuart_serial_tstc(plat);
	else
	return __raw_readb(&reg->us1) & US1_TDRE ? 0 : 1;
	}

	static int lpuart_serial_probe(struct udevice *dev)
	{
	struct lpuart_serial_platdata *plat = dev->platdata;

	if (is_lpuart32(dev))
	return _lpuart32_serial_init(plat);
	else
	return _lpuart_serial_init(plat);
	}

	static int lpuart_serial_ofdata_to_platdata(struct udevice *dev)
	{
	struct lpuart_serial_platdata *plat = dev->platdata;
	const void *blob = gd->fdt_blob;
	int node = dev->of_offset;
	fdt_addr_t addr;

	addr = dev_get_addr(dev);
	if (addr == FDT_ADDR_T_NONE)
	return -EINVAL;

	plat->reg = (void *)addr;
	plat->flags = dev_get_driver_data(dev);

	if (!fdt_node_check_compatible(blob, node, "fsl,ls1021a-lpuart"))
	plat->devtype = DEV_LS1021A;
	else if (!fdt_node_check_compatible(blob, node, "fsl,imx7ulp-lpuart"))
	plat->devtype = DEV_MX7ULP;
	else if (!fdt_node_check_compatible(blob, node, "fsl,vf610-lpuart"))
	plat->devtype = DEV_VF610;
	else if (!fdt_node_check_compatible(blob, node, "fsl,imx8qm-lpuart"))
	plat->devtype = DEV_IMX8;

	return 0;
	}

	static const struct dm_serial_ops lpuart_serial_ops = {
	.putc = lpuart_serial_putc,
	.pending = lpuart_serial_pending,
	.getc = lpuart_serial_getc,
	.setbrg = lpuart_serial_setbrg,
	};

	static const struct udevice_id lpuart_serial_ids[] = {
	{ .compatible = "fsl,ls1021a-lpuart", .data =
	LPUART_FLAG_REGMAP_32BIT_REG \| LPUART_FLAG_REGMAP_ENDIAN_BIG },
	{ .compatible = "fsl,imx7ulp-lpuart",
	.data = LPUART_FLAG_REGMAP_32BIT_REG },
	{ .compatible = "fsl,vf610-lpuart"},
	{ .compatible = "fsl,imx8qm-lpuart",
	.data = LPUART_FLAG_REGMAP_32BIT_REG },
	{ }
	};

	U_BOOT_DRIVER(serial_lpuart) = {
	.name = "serial_lpuart",
	.id = UCLASS_SERIAL,
	.of_match = lpuart_serial_ids,
	.ofdata_to_platdata = lpuart_serial_ofdata_to_platdata,
	.platdata_auto_alloc_size = sizeof(struct lpuart_serial_platdata),
	.probe = lpuart_serial_probe,
	.ops = &lpuart_serial_ops,
	.flags = DM_FLAG_PRE_RELOC,
	};