u-boot/drivers/serial/serial_mxc.c
Loic Poulain ad725073d1 serial: mxc: Speed-up character transmission
Instead of waiting for empty FIFO condition before writing a
character, wait for non-full FIFO condition.

This helps in saving several tens of milliseconds during boot
(depending verbosity).

Signed-off-by: Loic Poulain <loic.poulain@linaro.org>
Tested-by: Lothar Waßmann <LW@KARO-electronics.de>
Acked-by: Pali Rohár <pali@kernel.org>
Reviewed-by: Fabio Estevam <festevam@denx.de>
Tested-by: Fabio Estevam <festevam@denx.de>
2023-01-30 23:23:02 +01:00

431 lines
12 KiB
C

// SPDX-License-Identifier: GPL-2.0+
/*
* (c) 2007 Sascha Hauer <s.hauer@pengutronix.de>
*/
#include <common.h>
#include <dm.h>
#include <errno.h>
#include <watchdog.h>
#include <asm/arch/imx-regs.h>
#include <asm/arch/clock.h>
#include <asm/global_data.h>
#include <dm/platform_data/serial_mxc.h>
#include <serial.h>
#include <linux/compiler.h>
#include <linux/delay.h>
/* UART Control Register Bit Fields.*/
#define URXD_CHARRDY (1<<15)
#define URXD_ERR (1<<14)
#define URXD_OVRRUN (1<<13)
#define URXD_FRMERR (1<<12)
#define URXD_BRK (1<<11)
#define URXD_PRERR (1<<10)
#define URXD_RX_DATA (0xFF)
#define UCR1_ADEN (1<<15) /* Auto dectect interrupt */
#define UCR1_ADBR (1<<14) /* Auto detect baud rate */
#define UCR1_TRDYEN (1<<13) /* Transmitter ready interrupt enable */
#define UCR1_IDEN (1<<12) /* Idle condition interrupt */
#define UCR1_RRDYEN (1<<9) /* Recv ready interrupt enable */
#define UCR1_RDMAEN (1<<8) /* Recv ready DMA enable */
#define UCR1_IREN (1<<7) /* Infrared interface enable */
#define UCR1_TXMPTYEN (1<<6) /* Transimitter empty interrupt enable */
#define UCR1_RTSDEN (1<<5) /* RTS delta interrupt enable */
#define UCR1_SNDBRK (1<<4) /* Send break */
#define UCR1_TDMAEN (1<<3) /* Transmitter ready DMA enable */
#define UCR1_UARTCLKEN (1<<2) /* UART clock enabled */
#define UCR1_DOZE (1<<1) /* Doze */
#define UCR1_UARTEN (1<<0) /* UART enabled */
#define UCR2_ESCI (1<<15) /* Escape seq interrupt enable */
#define UCR2_IRTS (1<<14) /* Ignore RTS pin */
#define UCR2_CTSC (1<<13) /* CTS pin control */
#define UCR2_CTS (1<<12) /* Clear to send */
#define UCR2_ESCEN (1<<11) /* Escape enable */
#define UCR2_PREN (1<<8) /* Parity enable */
#define UCR2_PROE (1<<7) /* Parity odd/even */
#define UCR2_STPB (1<<6) /* Stop */
#define UCR2_WS (1<<5) /* Word size */
#define UCR2_RTSEN (1<<4) /* Request to send interrupt enable */
#define UCR2_TXEN (1<<2) /* Transmitter enabled */
#define UCR2_RXEN (1<<1) /* Receiver enabled */
#define UCR2_SRST (1<<0) /* SW reset */
#define UCR3_DTREN (1<<13) /* DTR interrupt enable */
#define UCR3_PARERREN (1<<12) /* Parity enable */
#define UCR3_FRAERREN (1<<11) /* Frame error interrupt enable */
#define UCR3_DSR (1<<10) /* Data set ready */
#define UCR3_DCD (1<<9) /* Data carrier detect */
#define UCR3_RI (1<<8) /* Ring indicator */
#define UCR3_ADNIMP (1<<7) /* Autobaud Detection Not Improved */
#define UCR3_RXDSEN (1<<6) /* Receive status interrupt enable */
#define UCR3_AIRINTEN (1<<5) /* Async IR wake interrupt enable */
#define UCR3_AWAKEN (1<<4) /* Async wake interrupt enable */
#define UCR3_REF25 (1<<3) /* Ref freq 25 MHz */
#define UCR3_REF30 (1<<2) /* Ref Freq 30 MHz */
/* imx8 names these bitsfields instead: */
#define UCR3_DTRDEN BIT(3) /* bit not used in this chip */
#define UCR3_RXDMUXSEL BIT(2) /* RXD muxed input selected; 'should always be set' */
#define UCR3_INVT (1<<1) /* Inverted Infrared transmission */
#define UCR3_BPEN (1<<0) /* Preset registers enable */
#define UCR4_CTSTL_32 (32<<10) /* CTS trigger level (32 chars) */
#define UCR4_INVR (1<<9) /* Inverted infrared reception */
#define UCR4_ENIRI (1<<8) /* Serial infrared interrupt enable */
#define UCR4_WKEN (1<<7) /* Wake interrupt enable */
#define UCR4_REF16 (1<<6) /* Ref freq 16 MHz */
#define UCR4_IRSC (1<<5) /* IR special case */
#define UCR4_TCEN (1<<3) /* Transmit complete interrupt enable */
#define UCR4_BKEN (1<<2) /* Break condition interrupt enable */
#define UCR4_OREN (1<<1) /* Receiver overrun interrupt enable */
#define UCR4_DREN (1<<0) /* Recv data ready interrupt enable */
#define UFCR_RXTL_SHF 0 /* Receiver trigger level shift */
#define UFCR_RFDIV (7<<7) /* Reference freq divider mask */
#define UFCR_RFDIV_SHF 7 /* Reference freq divider shift */
#define RFDIV 4 /* divide input clock by 2 */
#define UFCR_DCEDTE (1<<6) /* DTE mode select */
#define UFCR_TXTL_SHF 10 /* Transmitter trigger level shift */
#define USR1_PARITYERR (1<<15) /* Parity error interrupt flag */
#define USR1_RTSS (1<<14) /* RTS pin status */
#define USR1_TRDY (1<<13) /* Transmitter ready interrupt/dma flag */
#define USR1_RTSD (1<<12) /* RTS delta */
#define USR1_ESCF (1<<11) /* Escape seq interrupt flag */
#define USR1_FRAMERR (1<<10) /* Frame error interrupt flag */
#define USR1_RRDY (1<<9) /* Receiver ready interrupt/dma flag */
#define USR1_TIMEOUT (1<<7) /* Receive timeout interrupt status */
#define USR1_RXDS (1<<6) /* Receiver idle interrupt flag */
#define USR1_AIRINT (1<<5) /* Async IR wake interrupt flag */
#define USR1_AWAKE (1<<4) /* Aysnc wake interrupt flag */
#define USR2_ADET (1<<15) /* Auto baud rate detect complete */
#define USR2_TXFE (1<<14) /* Transmit buffer FIFO empty */
#define USR2_DTRF (1<<13) /* DTR edge interrupt flag */
#define USR2_IDLE (1<<12) /* Idle condition */
#define USR2_IRINT (1<<8) /* Serial infrared interrupt flag */
#define USR2_WAKE (1<<7) /* Wake */
#define USR2_RTSF (1<<4) /* RTS edge interrupt flag */
#define USR2_TXDC (1<<3) /* Transmitter complete */
#define USR2_BRCD (1<<2) /* Break condition */
#define USR2_ORE (1<<1) /* Overrun error */
#define USR2_RDR (1<<0) /* Recv data ready */
#define UTS_FRCPERR (1<<13) /* Force parity error */
#define UTS_LOOP (1<<12) /* Loop tx and rx */
#define UTS_TXEMPTY (1<<6) /* TxFIFO empty */
#define UTS_RXEMPTY (1<<5) /* RxFIFO empty */
#define UTS_TXFULL (1<<4) /* TxFIFO full */
#define UTS_RXFULL (1<<3) /* RxFIFO full */
#define UTS_SOFTRS (1<<0) /* Software reset */
#define TXTL 2 /* reset default */
#define RXTL 1 /* reset default */
DECLARE_GLOBAL_DATA_PTR;
struct mxc_uart {
u32 rxd;
u32 spare0[15];
u32 txd;
u32 spare1[15];
u32 cr1;
u32 cr2;
u32 cr3;
u32 cr4;
u32 fcr;
u32 sr1;
u32 sr2;
u32 esc;
u32 tim;
u32 bir;
u32 bmr;
u32 brc;
u32 onems;
u32 ts;
};
static void _mxc_serial_flush(struct mxc_uart *base)
{
unsigned int timeout = 4000;
if (!(readl(&base->cr1) & UCR1_UARTEN) ||
!(readl(&base->cr2) & UCR2_TXEN))
return;
while (!(readl(&base->sr2) & USR2_TXDC) && --timeout)
udelay(1);
}
static void _mxc_serial_init(struct mxc_uart *base, int use_dte)
{
_mxc_serial_flush(base);
writel(0, &base->cr1);
writel(0, &base->cr2);
while (!(readl(&base->cr2) & UCR2_SRST));
if (use_dte)
writel(0x404 | UCR3_ADNIMP, &base->cr3);
else
writel(0x704 | UCR3_ADNIMP, &base->cr3);
writel(0x704 | UCR3_ADNIMP, &base->cr3);
writel(0x8000, &base->cr4);
writel(0x2b, &base->esc);
writel(0, &base->tim);
writel(0, &base->ts);
}
static void _mxc_serial_setbrg(struct mxc_uart *base, unsigned long clk,
unsigned long baudrate, bool use_dte)
{
u32 tmp;
_mxc_serial_flush(base);
tmp = RFDIV << UFCR_RFDIV_SHF;
if (use_dte)
tmp |= UFCR_DCEDTE;
else
tmp |= (TXTL << UFCR_TXTL_SHF) | (RXTL << UFCR_RXTL_SHF);
writel(tmp, &base->fcr);
writel(0xf, &base->bir);
writel(clk / (2 * baudrate), &base->bmr);
writel(UCR2_WS | UCR2_IRTS | UCR2_RXEN | UCR2_TXEN | UCR2_SRST,
&base->cr2);
/*
* setting the baudrate triggers a reset, returning cr3 to its
* reset value but UCR3_RXDMUXSEL "should always be set."
* according to the imx8 reference-manual
*/
writel(readl(&base->cr3) | UCR3_RXDMUXSEL, &base->cr3);
writel(UCR1_UARTEN, &base->cr1);
}
#if !CONFIG_IS_ENABLED(DM_SERIAL)
#ifndef CFG_MXC_UART_BASE
#error "define CFG_MXC_UART_BASE to use the MXC UART driver"
#endif
#define mxc_base ((struct mxc_uart *)CFG_MXC_UART_BASE)
static void mxc_serial_setbrg(void)
{
u32 clk = imx_get_uartclk();
if (!gd->baudrate)
gd->baudrate = CONFIG_BAUDRATE;
_mxc_serial_setbrg(mxc_base, clk, gd->baudrate, false);
}
static int mxc_serial_getc(void)
{
while (readl(&mxc_base->ts) & UTS_RXEMPTY)
schedule();
return (readl(&mxc_base->rxd) & URXD_RX_DATA); /* mask out status from upper word */
}
static void mxc_serial_putc(const char c)
{
/* If \n, also do \r */
if (c == '\n')
serial_putc('\r');
/* wait for transmitter to be ready */
while (readl(&mxc_base->ts) & UTS_TXFULL)
schedule();
writel(c, &mxc_base->txd);
}
/* Test whether a character is in the RX buffer */
static int mxc_serial_tstc(void)
{
/* If receive fifo is empty, return false */
if (readl(&mxc_base->ts) & UTS_RXEMPTY)
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 mxc_serial_init(void)
{
_mxc_serial_init(mxc_base, false);
serial_setbrg();
return 0;
}
static int mxc_serial_stop(void)
{
_mxc_serial_flush(mxc_base);
return 0;
}
static struct serial_device mxc_serial_drv = {
.name = "mxc_serial",
.start = mxc_serial_init,
.stop = mxc_serial_stop,
.setbrg = mxc_serial_setbrg,
.putc = mxc_serial_putc,
.puts = default_serial_puts,
.getc = mxc_serial_getc,
.tstc = mxc_serial_tstc,
};
void mxc_serial_initialize(void)
{
serial_register(&mxc_serial_drv);
}
__weak struct serial_device *default_serial_console(void)
{
return &mxc_serial_drv;
}
#endif
#if CONFIG_IS_ENABLED(DM_SERIAL)
int mxc_serial_setbrg(struct udevice *dev, int baudrate)
{
struct mxc_serial_plat *plat = dev_get_plat(dev);
u32 clk = imx_get_uartclk();
_mxc_serial_setbrg(plat->reg, clk, baudrate, plat->use_dte);
return 0;
}
static int mxc_serial_probe(struct udevice *dev)
{
struct mxc_serial_plat *plat = dev_get_plat(dev);
_mxc_serial_init(plat->reg, plat->use_dte);
return 0;
}
static int mxc_serial_getc(struct udevice *dev)
{
struct mxc_serial_plat *plat = dev_get_plat(dev);
struct mxc_uart *const uart = plat->reg;
if (readl(&uart->ts) & UTS_RXEMPTY)
return -EAGAIN;
return readl(&uart->rxd) & URXD_RX_DATA;
}
static int mxc_serial_putc(struct udevice *dev, const char ch)
{
struct mxc_serial_plat *plat = dev_get_plat(dev);
struct mxc_uart *const uart = plat->reg;
if (readl(&uart->ts) & UTS_TXFULL)
return -EAGAIN;
writel(ch, &uart->txd);
return 0;
}
static int mxc_serial_pending(struct udevice *dev, bool input)
{
struct mxc_serial_plat *plat = dev_get_plat(dev);
struct mxc_uart *const uart = plat->reg;
uint32_t sr2 = readl(&uart->sr2);
if (input)
return sr2 & USR2_RDR ? 1 : 0;
else
return sr2 & USR2_TXDC ? 0 : 1;
}
static const struct dm_serial_ops mxc_serial_ops = {
.putc = mxc_serial_putc,
.pending = mxc_serial_pending,
.getc = mxc_serial_getc,
.setbrg = mxc_serial_setbrg,
};
#if CONFIG_IS_ENABLED(OF_CONTROL)
static int mxc_serial_of_to_plat(struct udevice *dev)
{
struct mxc_serial_plat *plat = dev_get_plat(dev);
fdt_addr_t addr;
addr = dev_read_addr(dev);
if (addr == FDT_ADDR_T_NONE)
return -EINVAL;
plat->reg = (struct mxc_uart *)addr;
plat->use_dte = fdtdec_get_bool(gd->fdt_blob, dev_of_offset(dev),
"fsl,dte-mode");
return 0;
}
static const struct udevice_id mxc_serial_ids[] = {
{ .compatible = "fsl,imx21-uart" },
{ .compatible = "fsl,imx53-uart" },
{ .compatible = "fsl,imx6sx-uart" },
{ .compatible = "fsl,imx6ul-uart" },
{ .compatible = "fsl,imx7d-uart" },
{ .compatible = "fsl,imx6q-uart" },
{ }
};
#endif
U_BOOT_DRIVER(serial_mxc) = {
.name = "serial_mxc",
.id = UCLASS_SERIAL,
#if CONFIG_IS_ENABLED(OF_CONTROL)
.of_match = mxc_serial_ids,
.of_to_plat = mxc_serial_of_to_plat,
.plat_auto = sizeof(struct mxc_serial_plat),
#endif
.probe = mxc_serial_probe,
.ops = &mxc_serial_ops,
.flags = DM_FLAG_PRE_RELOC,
};
#endif
#ifdef CONFIG_DEBUG_UART_MXC
#include <debug_uart.h>
static inline void _debug_uart_init(void)
{
struct mxc_uart *base = (struct mxc_uart *)CONFIG_VAL(DEBUG_UART_BASE);
_mxc_serial_init(base, false);
_mxc_serial_setbrg(base, CONFIG_DEBUG_UART_CLOCK,
CONFIG_BAUDRATE, false);
}
static inline void _debug_uart_putc(int ch)
{
struct mxc_uart *base = (struct mxc_uart *)CONFIG_VAL(DEBUG_UART_BASE);
while (!(readl(&base->ts) & UTS_TXEMPTY))
schedule();
writel(ch, &base->txd);
}
DEBUG_UART_FUNCS
#endif