diff options
Diffstat (limited to 'drivers/serial/serial_sifive.c')
| -rw-r--r-- | drivers/serial/serial_sifive.c | 215 |
1 files changed, 215 insertions, 0 deletions
diff --git a/drivers/serial/serial_sifive.c b/drivers/serial/serial_sifive.c new file mode 100644 index 0000000000..341728a690 --- /dev/null +++ b/drivers/serial/serial_sifive.c @@ -0,0 +1,215 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * Copyright (C) 2018 Anup Patel <anup@brainfault.org> + */ + +#include <clk.h> +#include <common.h> +#include <debug_uart.h> +#include <dm.h> +#include <errno.h> +#include <fdtdec.h> +#include <watchdog.h> +#include <asm/io.h> +#include <linux/compiler.h> +#include <serial.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 + +struct uart_sifive { + u32 txfifo; + u32 rxfifo; + u32 txctrl; + u32 rxctrl; + u32 ie; + u32 ip; + u32 div; +}; + +struct sifive_uart_platdata { + unsigned int clock; + int saved_input_char; + struct uart_sifive *regs; +}; + +/* Set up the baud rate in gd struct */ +static void _sifive_serial_setbrg(struct uart_sifive *regs, + unsigned long clock, unsigned long baud) +{ + writel((u32)((clock / baud) - 1), ®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) ? -EAGAIN : ch; +} + +static int sifive_serial_setbrg(struct udevice *dev, int baudrate) +{ + int err; + struct clk clk; + struct sifive_uart_platdata *platdata = dev_get_platdata(dev); + + err = clk_get_by_index(dev, 0, &clk); + if (!err) { + err = clk_get_rate(&clk); + if (!IS_ERR_VALUE(err)) + platdata->clock = err; + } else if (err != -ENOENT && err != -ENODEV && err != -ENOSYS) { + debug("SiFive UART failed to get clock\n"); + return err; + } + + if (!platdata->clock) + platdata->clock = dev_read_u32_default(dev, "clock-frequency", 0); + if (!platdata->clock) { + debug("SiFive UART clock not defined\n"); + return -EINVAL; + } + + _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; + + platdata->saved_input_char = 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; + + if (platdata->saved_input_char > 0) { + c = platdata->saved_input_char; + platdata->saved_input_char = 0; + return c; + } + + 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) { + if (platdata->saved_input_char > 0) + return 1; + platdata->saved_input_char = _sifive_serial_getc(regs); + return (platdata->saved_input_char > 0) ? 1 : 0; + } 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 |