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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_platdata {
- 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_platdata *platdata = dev_get_platdata(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;
- }
- }
- platdata->clock = clock;
- _sifive_serial_setbrg(platdata->regs, platdata->clock, baudrate);
- return 0;
- }
- static int sifive_serial_probe(struct udevice *dev)
- {
- struct sifive_uart_platdata *platdata = dev_get_platdata(dev);
- /* No need to reinitialize the UART after relocation */
- if (gd->flags & GD_FLG_RELOC)
- return 0;
- _sifive_serial_init(platdata->regs);
- return 0;
- }
- static int sifive_serial_getc(struct udevice *dev)
- {
- int c;
- struct sifive_uart_platdata *platdata = dev_get_platdata(dev);
- struct uart_sifive *regs = platdata->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_platdata *platdata = dev_get_platdata(dev);
- while ((rc = _sifive_serial_putc(platdata->regs, ch)) == -EAGAIN) ;
- return rc;
- }
- static int sifive_serial_pending(struct udevice *dev, bool input)
- {
- struct sifive_uart_platdata *platdata = dev_get_platdata(dev);
- struct uart_sifive *regs = platdata->regs;
- if (input)
- return (readl(®s->ip) & UART_IP_RXWM);
- else
- return !!(readl(®s->txfifo) & UART_TXFIFO_FULL);
- }
- static int sifive_serial_ofdata_to_platdata(struct udevice *dev)
- {
- struct sifive_uart_platdata *platdata = dev_get_platdata(dev);
- platdata->regs = (struct uart_sifive *)dev_read_addr(dev);
- if (IS_ERR(platdata->regs))
- return PTR_ERR(platdata->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,
- .ofdata_to_platdata = sifive_serial_ofdata_to_platdata,
- .platdata_auto_alloc_size = sizeof(struct sifive_uart_platdata),
- .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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