diff options
| author |   Michal Simek <michal.simek@xilinx.com> | 2019-10-08 16:12:06 +0200 |
|---|---|---|
| committer |   Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-10-11 08:38:07 +0200 |
| commit | d1a1af2cdf19770d69947769f5d5a16c39de93e6 (patch) | |
| tree | 41247e92d89415d42eb60ad1670ac7bc5fd91c2d /drivers/tty/hvc | |
| parent | serdev: Add ACPI devices by ResourceSource field (diff) | |
| download | linux-dev-d1a1af2cdf19770d69947769f5d5a16c39de93e6.tar.xz linux-dev-d1a1af2cdf19770d69947769f5d5a16c39de93e6.zip | |
hvc: dcc: Add earlycon support
Add DCC earlycon support for early printks. The patch is useful for SoC
bringup where HW serial console is broken.
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Link: https://lore.kernel.org/r/41e2920a6348e65b2e986b0e65b66531e87cd756.1570543923.git.michal.simek@xilinx.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty/hvc')
| -rw-r--r-- | drivers/tty/hvc/hvc_dcc.c | 28 |
1 files changed, 28 insertions, 0 deletions
diff --git a/drivers/tty/hvc/hvc_dcc.c b/drivers/tty/hvc/hvc_dcc.c index 02629a1f193d..8e0edb7d93fd 100644 --- a/drivers/tty/hvc/hvc_dcc.c +++ b/drivers/tty/hvc/hvc_dcc.c @@ -1,7 +1,10 @@ // SPDX-License-Identifier: GPL-2.0 /* Copyright (c) 2010, 2014 The Linux Foundation. All rights reserved. */ +#include <linux/console.h> #include <linux/init.h> +#include <linux/serial.h> +#include <linux/serial_core.h> #include <asm/dcc.h> #include <asm/processor.h> @@ -12,6 +15,31 @@ #define DCC_STATUS_RX (1 << 30) #define DCC_STATUS_TX (1 << 29) +static void dcc_uart_console_putchar(struct uart_port *port, int ch) +{ + while (__dcc_getstatus() & DCC_STATUS_TX) + cpu_relax(); + + __dcc_putchar(ch); +} + +static void dcc_early_write(struct console *con, const char *s, unsigned n) +{ + struct earlycon_device *dev = con->data; + + uart_console_write(&dev->port, s, n, dcc_uart_console_putchar); +} + +static int __init dcc_early_console_setup(struct earlycon_device *device, + const char *opt) +{ + device->con->write = dcc_early_write; + + return 0; +} + +EARLYCON_DECLARE(dcc, dcc_early_console_setup); + static int hvc_dcc_put_chars(uint32_t vt, const char *buf, int count) { int i; |