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https://github.com/AsahiLinux/u-boot
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fb84517d52
ARM semihosting provides no provisions for determining if there is pending input. The only way to determine if there is console input is to do a read (and block until the user types something). For this reason, we always return true for tstc (since you will always get input if you try). However, this behavior can cause problems for code which expects tstc to eventually be empty. In query_console_serial, there is the following construct: /* empty input buffer */ while (tstc()) getchar(); with the current implementation, this effectively turns into an infinite loop. To avoid this, fake tstc by returning false half of the time. This is generally OK because the other common construct looks like do { if (tstc()) process(getchar()); } while (!timeout()); so it's fine if we only read a new character every other loop. This will break things like CYGACC_COMM_IF_GETC_TIMEOUT, but that could be reworked to test on the timeout instead of calling tstc again (and ymodem over semihosted serial is not that useful in the first place). Signed-off-by: Sean Anderson <sean.anderson@seco.com>
203 lines
3.6 KiB
C
203 lines
3.6 KiB
C
// SPDX-License-Identifier: GPL-2.0+
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/*
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* Copyright (C) 2022 Sean Anderson <sean.anderson@seco.com>
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*/
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#include <common.h>
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#include <dm.h>
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#include <malloc.h>
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#include <serial.h>
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#include <semihosting.h>
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/**
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* struct smh_serial_priv - Semihosting serial private data
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* @infd: stdin file descriptor (or error)
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* @outfd: stdout file descriptor (or error)
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* @counter: Counter used to fake pending every other call
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*/
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struct smh_serial_priv {
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int infd;
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int outfd;
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unsigned counter;
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};
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#if CONFIG_IS_ENABLED(DM_SERIAL)
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static int smh_serial_getc(struct udevice *dev)
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{
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char ch = 0;
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struct smh_serial_priv *priv = dev_get_priv(dev);
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if (priv->infd < 0)
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return smh_getc();
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smh_read(priv->infd, &ch, sizeof(ch));
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return ch;
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}
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static int smh_serial_putc(struct udevice *dev, const char ch)
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{
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smh_putc(ch);
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return 0;
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}
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static ssize_t smh_serial_puts(struct udevice *dev, const char *s, size_t len)
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{
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int ret;
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struct smh_serial_priv *priv = dev_get_priv(dev);
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unsigned long written;
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if (priv->outfd < 0) {
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char *buf;
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/* Try and avoid a copy if we can */
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if (!s[len + 1]) {
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smh_puts(s);
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return len;
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}
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buf = strndup(s, len);
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if (!buf)
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return -ENOMEM;
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smh_puts(buf);
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free(buf);
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return len;
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}
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ret = smh_write(priv->outfd, s, len, &written);
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if (written)
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return written;
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return ret;
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}
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static int smh_serial_pending(struct udevice *dev, bool input)
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{
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struct smh_serial_priv *priv = dev_get_priv(dev);
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if (input)
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return priv->counter++ & 1;
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return false;
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}
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static const struct dm_serial_ops smh_serial_ops = {
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.putc = smh_serial_putc,
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.puts = smh_serial_puts,
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.getc = smh_serial_getc,
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.pending = smh_serial_pending,
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};
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static int smh_serial_bind(struct udevice *dev)
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{
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if (semihosting_enabled())
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return 0;
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return -ENOENT;
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}
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static int smh_serial_probe(struct udevice *dev)
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{
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struct smh_serial_priv *priv = dev_get_priv(dev);
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priv->infd = smh_open(":tt", MODE_READ);
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priv->outfd = smh_open(":tt", MODE_WRITE);
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return 0;
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}
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U_BOOT_DRIVER(smh_serial) = {
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.name = "serial_semihosting",
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.id = UCLASS_SERIAL,
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.bind = smh_serial_bind,
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.probe = smh_serial_probe,
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.priv_auto = sizeof(struct smh_serial_priv),
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.ops = &smh_serial_ops,
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.flags = DM_FLAG_PRE_RELOC,
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};
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U_BOOT_DRVINFO(smh_serial) = {
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.name = "serial_semihosting",
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};
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#else /* DM_SERIAL */
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static int infd = -ENODEV;
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static int outfd = -ENODEV;
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static unsigned counter = 1;
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static int smh_serial_start(void)
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{
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infd = smh_open(":tt", MODE_READ);
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outfd = smh_open(":tt", MODE_WRITE);
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return 0;
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}
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static int smh_serial_stop(void)
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{
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if (outfd >= 0)
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smh_close(outfd);
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return 0;
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}
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static void smh_serial_setbrg(void)
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{
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}
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static int smh_serial_getc(void)
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{
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char ch = 0;
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if (infd < 0)
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return smh_getc();
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smh_read(infd, &ch, sizeof(ch));
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return ch;
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}
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static int smh_serial_tstc(void)
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{
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return counter++ & 1;
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}
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static void smh_serial_puts(const char *s)
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{
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ulong unused;
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if (outfd < 0)
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smh_puts(s);
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else
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smh_write(outfd, s, strlen(s), &unused);
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}
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struct serial_device serial_smh_device = {
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.name = "serial_smh",
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.start = smh_serial_start,
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.stop = smh_serial_stop,
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.setbrg = smh_serial_setbrg,
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.getc = smh_serial_getc,
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.tstc = smh_serial_tstc,
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.putc = smh_putc,
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.puts = smh_serial_puts,
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};
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void smh_serial_initialize(void)
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{
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if (semihosting_enabled())
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serial_register(&serial_smh_device);
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}
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__weak struct serial_device *default_serial_console(void)
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{
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return &serial_smh_device;
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}
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#endif
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#ifdef CONFIG_DEBUG_UART_SEMIHOSTING
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#include <debug_uart.h>
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static inline void _debug_uart_init(void)
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{
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}
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static inline void _debug_uart_putc(int c)
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{
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smh_putc(c);
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}
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DEBUG_UART_FUNCS
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#endif
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