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path: root/drivers/serial/serial_sifive.c
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Diffstat (limited to 'drivers/serial/serial_sifive.c')
-rw-r--r--drivers/serial/serial_sifive.c215
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), &regs->div);
+}
+
+static void _sifive_serial_init(struct uart_sifive *regs)
+{
+ writel(UART_TXCTRL_TXEN, &regs->txctrl);
+ writel(UART_RXCTRL_RXEN, &regs->rxctrl);
+ writel(0, &regs->ie);
+}
+
+static int _sifive_serial_putc(struct uart_sifive *regs, const char c)
+{
+ if (readl(&regs->txfifo) & UART_TXFIFO_FULL)
+ return -EAGAIN;
+
+ writel(c, &regs->txfifo);
+
+ return 0;
+}
+
+static int _sifive_serial_getc(struct uart_sifive *regs)
+{
+ int ch = readl(&regs->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(&regs->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