diff options
Diffstat (limited to 'drivers/tty/hvc/hvc_dcc.c')
| -rw-r--r-- | drivers/tty/hvc/hvc_dcc.c | 63 |
1 files changed, 23 insertions, 40 deletions
diff --git a/drivers/tty/hvc/hvc_dcc.c b/drivers/tty/hvc/hvc_dcc.c index 44fbebab507..809920d80a6 100644 --- a/drivers/tty/hvc/hvc_dcc.c +++ b/drivers/tty/hvc/hvc_dcc.c @@ -1,4 +1,4 @@ -/* Copyright (c) 2010, Code Aurora Forum. All rights reserved. +/* Copyright (c) 2010, 2014 The Linux Foundation. All rights reserved. * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 and @@ -8,20 +8,11 @@ * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. - * - * You should have received a copy of the GNU General Public License - * along with this program; if not, write to the Free Software - * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA - * 02110-1301, USA. */ -#include <linux/console.h> -#include <linux/delay.h> -#include <linux/err.h> #include <linux/init.h> -#include <linux/moduleparam.h> -#include <linux/types.h> +#include <asm/dcc.h> #include <asm/processor.h> #include "hvc_console.h" @@ -30,35 +21,6 @@ #define DCC_STATUS_RX (1 << 30) #define DCC_STATUS_TX (1 << 29) -static inline u32 __dcc_getstatus(void) -{ - u32 __ret; - asm volatile("mrc p14, 0, %0, c0, c1, 0 @ read comms ctrl reg" - : "=r" (__ret) : : "cc"); - - return __ret; -} - - -static inline char __dcc_getchar(void) -{ - char __c; - - asm volatile("mrc p14, 0, %0, c0, c5, 0 @ read comms data reg" - : "=r" (__c)); - isb(); - - return __c; -} - -static inline void __dcc_putchar(char c) -{ - asm volatile("mcr p14, 0, %0, c0, c5, 0 @ write a char" - : /* no output register */ - : "r" (c)); - isb(); -} - static int hvc_dcc_put_chars(uint32_t vt, const char *buf, int count) { int i; @@ -86,6 +48,21 @@ static int hvc_dcc_get_chars(uint32_t vt, char *buf, int count) return i; } +static bool hvc_dcc_check(void) +{ + unsigned long time = jiffies + (HZ / 10); + + /* Write a test character to check if it is handled */ + __dcc_putchar('\n'); + + while (time_is_after_jiffies(time)) { + if (!(__dcc_getstatus() & DCC_STATUS_TX)) + return true; + } + + return false; +} + static const struct hv_ops hvc_dcc_get_put_ops = { .get_chars = hvc_dcc_get_chars, .put_chars = hvc_dcc_put_chars, @@ -93,6 +70,9 @@ static const struct hv_ops hvc_dcc_get_put_ops = { static int __init hvc_dcc_console_init(void) { + if (!hvc_dcc_check()) + return -ENODEV; + hvc_instantiate(0, 0, &hvc_dcc_get_put_ops); return 0; } @@ -100,6 +80,9 @@ console_initcall(hvc_dcc_console_init); static int __init hvc_dcc_init(void) { + if (!hvc_dcc_check()) + return -ENODEV; + hvc_alloc(0, 0, &hvc_dcc_get_put_ops, 128); return 0; } |