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u-boot/drivers/serial/serial_mtk.c
Weijie Gao 0b9f1ae586 serial: mtk: rewrite the setbrg function 
Currently the setbrg logic of serial-mtk is messy, and should be rewritten.
Also an option is added to make it possible to use highspeed-3 mode for all
bauds.

The new logic is:
1. If baud clock > 12MHz
   a) If baud <= 115200, highspeed-0 mode will be used (ns16550 compatible)
   b) If baud <= 576000, highspeed-2 mode will be used
   c) any bauds > 576000, highspeed-3 mode will be used
2. If baud clock <= 12MHz
   Forced highspeed-3 mode
   a) If baud <= 115200, calculates the divisor using DIV_ROUND_CLOSEST
   b) any bauds > 115200, the same as 1. c)

Signed-off-by: Weijie Gao <weijie.gao@mediatek.com>
2021-03-20 16:24:27 -04:00

453 lines
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// SPDX-License-Identifier: GPL-2.0
/*
* MediaTek High-speed UART driver
*
* Copyright (C) 2018 MediaTek Inc.
* Author: Weijie Gao <weijie.gao@mediatek.com>
*/
#include <clk.h>
#include <common.h>
#include <div64.h>
#include <dm.h>
#include <errno.h>
#include <log.h>
#include <serial.h>
#include <watchdog.h>
#include <asm/global_data.h>
#include <asm/io.h>
#include <asm/types.h>
#include <linux/err.h>
struct mtk_serial_regs {
u32 rbr;
u32 ier;
u32 fcr;
u32 lcr;
u32 mcr;
u32 lsr;
u32 msr;
u32 spr;
u32 mdr1;
u32 highspeed;
u32 sample_count;
u32 sample_point;
u32 fracdiv_l;
u32 fracdiv_m;
u32 escape_en;
u32 guard;
u32 rx_sel;
};
#define thr rbr
#define iir fcr
#define dll rbr
#define dlm ier
#define UART_LCR_WLS_8 0x03 /* 8 bit character length */
#define UART_LCR_DLAB 0x80 /* Divisor latch access bit */
#define UART_LSR_DR 0x01 /* Data ready */
#define UART_LSR_THRE 0x20 /* Xmit holding register empty */
#define UART_LSR_TEMT 0x40 /* Xmitter empty */
#define UART_MCR_DTR 0x01 /* DTR */
#define UART_MCR_RTS 0x02 /* RTS */
#define UART_FCR_FIFO_EN 0x01 /* Fifo enable */
#define UART_FCR_RXSR 0x02 /* Receiver soft reset */
#define UART_FCR_TXSR 0x04 /* Transmitter soft reset */
#define UART_MCRVAL (UART_MCR_DTR | \
UART_MCR_RTS)
/* Clear & enable FIFOs */
#define UART_FCRVAL (UART_FCR_FIFO_EN | \
UART_FCR_RXSR | \
UART_FCR_TXSR)
/* the data is correct if the real baud is within 3%. */
#define BAUD_ALLOW_MAX(baud) ((baud) + (baud) * 3 / 100)
#define BAUD_ALLOW_MIX(baud) ((baud) - (baud) * 3 / 100)
struct mtk_serial_priv {
struct mtk_serial_regs __iomem *regs;
u32 clock;
bool force_highspeed;
};
static void _mtk_serial_setbrg(struct mtk_serial_priv *priv, int baud)
{
u32 quot, realbaud, samplecount = 1;
/* Special case for low baud clock */
if (baud <= 115200 && priv->clock <= 12000000) {
writel(3, &priv->regs->highspeed);
quot = DIV_ROUND_CLOSEST(priv->clock, 256 * baud);
if (quot == 0)
quot = 1;
samplecount = DIV_ROUND_CLOSEST(priv->clock, quot * baud);
realbaud = priv->clock / samplecount / quot;
if (realbaud > BAUD_ALLOW_MAX(baud) ||
realbaud < BAUD_ALLOW_MIX(baud)) {
pr_info("baud %d can't be handled\n", baud);
}
goto set_baud;
}
if (priv->force_highspeed)
goto use_hs3;
if (baud <= 115200) {
writel(0, &priv->regs->highspeed);
quot = DIV_ROUND_CLOSEST(priv->clock, 16 * baud);
} else if (baud <= 576000) {
writel(2, &priv->regs->highspeed);
/* Set to next lower baudrate supported */
if ((baud == 500000) || (baud == 576000))
baud = 460800;
quot = DIV_ROUND_UP(priv->clock, 4 * baud);
} else {
use_hs3:
writel(3, &priv->regs->highspeed);
quot = DIV_ROUND_UP(priv->clock, 256 * baud);
samplecount = DIV_ROUND_CLOSEST(priv->clock, quot * baud);
}
set_baud:
/* set divisor */
writel(UART_LCR_WLS_8 | UART_LCR_DLAB, &priv->regs->lcr);
writel(quot & 0xff, &priv->regs->dll);
writel((quot >> 8) & 0xff, &priv->regs->dlm);
writel(UART_LCR_WLS_8, &priv->regs->lcr);
/* set highspeed mode sample count & point */
writel(samplecount - 1, &priv->regs->sample_count);
writel((samplecount - 2) >> 1, &priv->regs->sample_point);
}
static int _mtk_serial_putc(struct mtk_serial_priv *priv, const char ch)
{
if (!(readl(&priv->regs->lsr) & UART_LSR_THRE))
return -EAGAIN;
writel(ch, &priv->regs->thr);
if (ch == '\n')
WATCHDOG_RESET();
return 0;
}
static int _mtk_serial_getc(struct mtk_serial_priv *priv)
{
if (!(readl(&priv->regs->lsr) & UART_LSR_DR))
return -EAGAIN;
return readl(&priv->regs->rbr);
}
static int _mtk_serial_pending(struct mtk_serial_priv *priv, bool input)
{
if (input)
return (readl(&priv->regs->lsr) & UART_LSR_DR) ? 1 : 0;
else
return (readl(&priv->regs->lsr) & UART_LSR_THRE) ? 0 : 1;
}
#if defined(CONFIG_DM_SERIAL) && \
(!defined(CONFIG_SPL_BUILD) || defined(CONFIG_SPL_DM))
static int mtk_serial_setbrg(struct udevice *dev, int baudrate)
{
struct mtk_serial_priv *priv = dev_get_priv(dev);
_mtk_serial_setbrg(priv, baudrate);
return 0;
}
static int mtk_serial_putc(struct udevice *dev, const char ch)
{
struct mtk_serial_priv *priv = dev_get_priv(dev);
return _mtk_serial_putc(priv, ch);
}
static int mtk_serial_getc(struct udevice *dev)
{
struct mtk_serial_priv *priv = dev_get_priv(dev);
return _mtk_serial_getc(priv);
}
static int mtk_serial_pending(struct udevice *dev, bool input)
{
struct mtk_serial_priv *priv = dev_get_priv(dev);
return _mtk_serial_pending(priv, input);
}
static int mtk_serial_probe(struct udevice *dev)
{
struct mtk_serial_priv *priv = dev_get_priv(dev);
/* Disable interrupt */
writel(0, &priv->regs->ier);
writel(UART_MCRVAL, &priv->regs->mcr);
writel(UART_FCRVAL, &priv->regs->fcr);
return 0;
}
static int mtk_serial_of_to_plat(struct udevice *dev)
{
struct mtk_serial_priv *priv = dev_get_priv(dev);
fdt_addr_t addr;
struct clk clk;
int err;
addr = dev_read_addr(dev);
if (addr == FDT_ADDR_T_NONE)
return -EINVAL;
priv->regs = map_physmem(addr, 0, MAP_NOCACHE);
err = clk_get_by_index(dev, 0, &clk);
if (!err) {
err = clk_get_rate(&clk);
if (!IS_ERR_VALUE(err))
priv->clock = err;
} else if (err != -ENOENT && err != -ENODEV && err != -ENOSYS) {
debug("mtk_serial: failed to get clock\n");
return err;
}
if (!priv->clock)
priv->clock = dev_read_u32_default(dev, "clock-frequency", 0);
if (!priv->clock) {
debug("mtk_serial: clock not defined\n");
return -EINVAL;
}
priv->force_highspeed = dev_read_bool(dev, "mediatek,force-highspeed");
return 0;
}
static const struct dm_serial_ops mtk_serial_ops = {
.putc = mtk_serial_putc,
.pending = mtk_serial_pending,
.getc = mtk_serial_getc,
.setbrg = mtk_serial_setbrg,
};
static const struct udevice_id mtk_serial_ids[] = {
{ .compatible = "mediatek,hsuart" },
{ .compatible = "mediatek,mt6577-uart" },
{ }
};
U_BOOT_DRIVER(serial_mtk) = {
.name = "serial_mtk",
.id = UCLASS_SERIAL,
.of_match = mtk_serial_ids,
.of_to_plat = mtk_serial_of_to_plat,
.priv_auto = sizeof(struct mtk_serial_priv),
.probe = mtk_serial_probe,
.ops = &mtk_serial_ops,
.flags = DM_FLAG_PRE_RELOC,
};
#else
DECLARE_GLOBAL_DATA_PTR;
#define DECLARE_HSUART_PRIV(port) \
static struct mtk_serial_priv mtk_hsuart##port = { \
.regs = (struct mtk_serial_regs *)CONFIG_SYS_NS16550_COM##port, \
.clock = CONFIG_SYS_NS16550_CLK \
};
#define DECLARE_HSUART_FUNCTIONS(port) \
static int mtk_serial##port##_init(void) \
{ \
writel(0, &mtk_hsuart##port.regs->ier); \
writel(UART_MCRVAL, &mtk_hsuart##port.regs->mcr); \
writel(UART_FCRVAL, &mtk_hsuart##port.regs->fcr); \
_mtk_serial_setbrg(&mtk_hsuart##port, gd->baudrate); \
return 0 ; \
} \
static void mtk_serial##port##_setbrg(void) \
{ \
_mtk_serial_setbrg(&mtk_hsuart##port, gd->baudrate); \
} \
static int mtk_serial##port##_getc(void) \
{ \
int err; \
do { \
err = _mtk_serial_getc(&mtk_hsuart##port); \
if (err == -EAGAIN) \
WATCHDOG_RESET(); \
} while (err == -EAGAIN); \
return err >= 0 ? err : 0; \
} \
static int mtk_serial##port##_tstc(void) \
{ \
return _mtk_serial_pending(&mtk_hsuart##port, true); \
} \
static void mtk_serial##port##_putc(const char c) \
{ \
int err; \
if (c == '\n') \
mtk_serial##port##_putc('\r'); \
do { \
err = _mtk_serial_putc(&mtk_hsuart##port, c); \
} while (err == -EAGAIN); \
} \
static void mtk_serial##port##_puts(const char *s) \
{ \
while (*s) { \
mtk_serial##port##_putc(*s++); \
} \
}
/* Serial device descriptor */
#define INIT_HSUART_STRUCTURE(port, __name) { \
.name = __name, \
.start = mtk_serial##port##_init, \
.stop = NULL, \
.setbrg = mtk_serial##port##_setbrg, \
.getc = mtk_serial##port##_getc, \
.tstc = mtk_serial##port##_tstc, \
.putc = mtk_serial##port##_putc, \
.puts = mtk_serial##port##_puts, \
}
#define DECLARE_HSUART(port, __name) \
DECLARE_HSUART_PRIV(port); \
DECLARE_HSUART_FUNCTIONS(port); \
struct serial_device mtk_hsuart##port##_device = \
INIT_HSUART_STRUCTURE(port, __name);
#if !defined(CONFIG_CONS_INDEX)
#elif (CONFIG_CONS_INDEX < 1) || (CONFIG_CONS_INDEX > 6)
#error "Invalid console index value."
#endif
#if CONFIG_CONS_INDEX == 1 && !defined(CONFIG_SYS_NS16550_COM1)
#error "Console port 1 defined but not configured."
#elif CONFIG_CONS_INDEX == 2 && !defined(CONFIG_SYS_NS16550_COM2)
#error "Console port 2 defined but not configured."
#elif CONFIG_CONS_INDEX == 3 && !defined(CONFIG_SYS_NS16550_COM3)
#error "Console port 3 defined but not configured."
#elif CONFIG_CONS_INDEX == 4 && !defined(CONFIG_SYS_NS16550_COM4)
#error "Console port 4 defined but not configured."
#elif CONFIG_CONS_INDEX == 5 && !defined(CONFIG_SYS_NS16550_COM5)
#error "Console port 5 defined but not configured."
#elif CONFIG_CONS_INDEX == 6 && !defined(CONFIG_SYS_NS16550_COM6)
#error "Console port 6 defined but not configured."
#endif
#if defined(CONFIG_SYS_NS16550_COM1)
DECLARE_HSUART(1, "mtk-hsuart0");
#endif
#if defined(CONFIG_SYS_NS16550_COM2)
DECLARE_HSUART(2, "mtk-hsuart1");
#endif
#if defined(CONFIG_SYS_NS16550_COM3)
DECLARE_HSUART(3, "mtk-hsuart2");
#endif
#if defined(CONFIG_SYS_NS16550_COM4)
DECLARE_HSUART(4, "mtk-hsuart3");
#endif
#if defined(CONFIG_SYS_NS16550_COM5)
DECLARE_HSUART(5, "mtk-hsuart4");
#endif
#if defined(CONFIG_SYS_NS16550_COM6)
DECLARE_HSUART(6, "mtk-hsuart5");
#endif
__weak struct serial_device *default_serial_console(void)
{
#if CONFIG_CONS_INDEX == 1
return &mtk_hsuart1_device;
#elif CONFIG_CONS_INDEX == 2
return &mtk_hsuart2_device;
#elif CONFIG_CONS_INDEX == 3
return &mtk_hsuart3_device;
#elif CONFIG_CONS_INDEX == 4
return &mtk_hsuart4_device;
#elif CONFIG_CONS_INDEX == 5
return &mtk_hsuart5_device;
#elif CONFIG_CONS_INDEX == 6
return &mtk_hsuart6_device;
#else
#error "Bad CONFIG_CONS_INDEX."
#endif
}
void mtk_serial_initialize(void)
{
#if defined(CONFIG_SYS_NS16550_COM1)
serial_register(&mtk_hsuart1_device);
#endif
#if defined(CONFIG_SYS_NS16550_COM2)
serial_register(&mtk_hsuart2_device);
#endif
#if defined(CONFIG_SYS_NS16550_COM3)
serial_register(&mtk_hsuart3_device);
#endif
#if defined(CONFIG_SYS_NS16550_COM4)
serial_register(&mtk_hsuart4_device);
#endif
#if defined(CONFIG_SYS_NS16550_COM5)
serial_register(&mtk_hsuart5_device);
#endif
#if defined(CONFIG_SYS_NS16550_COM6)
serial_register(&mtk_hsuart6_device);
#endif
}
#endif
#ifdef CONFIG_DEBUG_UART_MTK
#include <debug_uart.h>
static inline void _debug_uart_init(void)
{
struct mtk_serial_priv priv;
priv.regs = (void *) CONFIG_DEBUG_UART_BASE;
priv.clock = CONFIG_DEBUG_UART_CLOCK;
writel(0, &priv.regs->ier);
writel(UART_MCRVAL, &priv.regs->mcr);
writel(UART_FCRVAL, &priv.regs->fcr);
_mtk_serial_setbrg(&priv, CONFIG_BAUDRATE);
}
static inline void _debug_uart_putc(int ch)
{
struct mtk_serial_regs __iomem *regs =
(void *) CONFIG_DEBUG_UART_BASE;
while (!(readl(&regs->lsr) & UART_LSR_THRE))
;
writel(ch, &regs->thr);
}
DEBUG_UART_FUNCS
#endif
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