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// SPDX-License-Identifier: GPL-2.0+
/*
* Copyright (C) 2018 Anup Patel <anup@brainfault.org>
*/
#include <common.h>
#include <clk.h>
#include <debug_uart.h>
#include <dm.h>
#include <errno.h>
#include <fdtdec.h>
#include <log.h>
#include <watchdog.h>
#include <asm/io.h>
#include <linux/compiler.h>
#include <serial.h>
#include <linux/err.h>
DECLARE_GLOBAL_DATA_PTR;
#define UART_TXFIFO_FULL 0x80000000
#define UART_RXFIFO_EMPTY 0x80000000
#define UART_RXFIFO_DATA 0x000000ff
#define UART_TXCTRL_TXEN 0x1
#define UART_RXCTRL_RXEN 0x1
/* IP register */
#define UART_IP_RXWM 0x2
struct uart_sifive {
u32 txfifo;
u32 rxfifo;
u32 txctrl;
u32 rxctrl;
u32 ie;
u32 ip;
u32 div;
};
struct sifive_uart_plat {
unsigned long clock;
struct uart_sifive *regs;
};
/**
* Find minimum divisor divides in_freq to max_target_hz;
* Based on uart driver n SiFive FSBL.
*
* f_baud = f_in / (div + 1) => div = (f_in / f_baud) - 1
* The nearest integer solution requires rounding up as to not exceed
* max_target_hz.
* div = ceil(f_in / f_baud) - 1
* = floor((f_in - 1 + f_baud) / f_baud) - 1
* This should not overflow as long as (f_in - 1 + f_baud) does not exceed
* 2^32 - 1, which is unlikely since we represent frequencies in kHz.
*/
static inline unsigned int uart_min_clk_divisor(unsigned long in_freq,
unsigned long max_target_hz)
{
unsigned long quotient =
(in_freq + max_target_hz - 1) / (max_target_hz);
/* Avoid underflow */
if (quotient == 0)
return 0;
else
return quotient - 1;
}
/* Set up the baud rate in gd struct */
static void _sifive_serial_setbrg(struct uart_sifive *regs,
unsigned long clock, unsigned long baud)
{
writel((uart_min_clk_divisor(clock, baud)), ®s->div);
}
static void _sifive_serial_init(struct uart_sifive *regs)
{
writel(UART_TXCTRL_TXEN, ®s->txctrl);
writel(UART_RXCTRL_RXEN, ®s->rxctrl);
writel(0, ®s->ie);
}
static int _sifive_serial_putc(struct uart_sifive *regs, const char c)
{
if (readl(®s->txfifo) & UART_TXFIFO_FULL)
return -EAGAIN;
writel(c, ®s->txfifo);
return 0;
}
static int _sifive_serial_getc(struct uart_sifive *regs)
{
int ch = readl(®s->rxfifo);
if (ch & UART_RXFIFO_EMPTY)
return -EAGAIN;
ch &= UART_RXFIFO_DATA;
return ch;
}
static int sifive_serial_setbrg(struct udevice *dev, int baudrate)
{
int ret;
struct clk clk;
struct sifive_uart_plat *plat = dev_get_plat(dev);
u32 clock = 0;
ret = clk_get_by_index(dev, 0, &clk);
if (IS_ERR_VALUE(ret)) {
debug("SiFive UART failed to get clock\n");
ret = dev_read_u32(dev, "clock-frequency", &clock);
if (IS_ERR_VALUE(ret)) {
debug("SiFive UART clock not defined\n");
return 0;
}
} else {
clock = clk_get_rate(&clk);
if (IS_ERR_VALUE(clock)) {
debug("SiFive UART clock get rate failed\n");
return 0;
}
}
plat->clock = clock;
_sifive_serial_setbrg(plat->regs, plat->clock, baudrate);
return 0;
}
static int sifive_serial_probe(struct udevice *dev)
{
struct sifive_uart_plat *plat = dev_get_plat(dev);
/* No need to reinitialize the UART after relocation */
if (gd->flags & GD_FLG_RELOC)
return 0;
_sifive_serial_init(plat->regs);
return 0;
}
static int sifive_serial_getc(struct udevice *dev)
{
int c;
struct sifive_uart_plat *plat = dev_get_plat(dev);
struct uart_sifive *regs = plat->regs;
while ((c = _sifive_serial_getc(regs)) == -EAGAIN) ;
return c;
}
static int sifive_serial_putc(struct udevice *dev, const char ch)
{
int rc;
struct sifive_uart_plat *plat = dev_get_plat(dev);
while ((rc = _sifive_serial_putc(plat->regs, ch)) == -EAGAIN) ;
return rc;
}
static int sifive_serial_pending(struct udevice *dev, bool input)
{
struct sifive_uart_plat *plat = dev_get_plat(dev);
struct uart_sifive *regs = plat->regs;
if (input)
return (readl(®s->ip) & UART_IP_RXWM);
else
return !!(readl(®s->txfifo) & UART_TXFIFO_FULL);
}
static int sifive_serial_of_to_plat(struct udevice *dev)
{
struct sifive_uart_plat *plat = dev_get_plat(dev);
plat->regs = (struct uart_sifive *)dev_read_addr(dev);
if (IS_ERR(plat->regs))
return PTR_ERR(plat->regs);
return 0;
}
static const struct dm_serial_ops sifive_serial_ops = {
.putc = sifive_serial_putc,
.getc = sifive_serial_getc,
.pending = sifive_serial_pending,
.setbrg = sifive_serial_setbrg,
};
static const struct udevice_id sifive_serial_ids[] = {
{ .compatible = "sifive,uart0" },
{ }
};
U_BOOT_DRIVER(serial_sifive) = {
.name = "serial_sifive",
.id = UCLASS_SERIAL,
.of_match = sifive_serial_ids,
.of_to_plat = sifive_serial_of_to_plat,
.plat_auto = sizeof(struct sifive_uart_plat),
.probe = sifive_serial_probe,
.ops = &sifive_serial_ops,
};
#ifdef CONFIG_DEBUG_UART_SIFIVE
static inline void _debug_uart_init(void)
{
struct uart_sifive *regs =
(struct uart_sifive *)CONFIG_DEBUG_UART_BASE;
_sifive_serial_setbrg(regs, CONFIG_DEBUG_UART_CLOCK,
CONFIG_BAUDRATE);
_sifive_serial_init(regs);
}
static inline void _debug_uart_putc(int ch)
{
struct uart_sifive *regs =
(struct uart_sifive *)CONFIG_DEBUG_UART_BASE;
while (_sifive_serial_putc(regs, ch) == -EAGAIN)
WATCHDOG_RESET();
}
DEBUG_UART_FUNCS
#endif
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