1 /* Copyright (c) 2010, Code Aurora Forum. All rights reserved. 2 * 3 * This program is free software; you can redistribute it and/or modify 4 * it under the terms of the GNU General Public License version 2 and 5 * only version 2 as published by the Free Software Foundation. 6 * 7 * This program is distributed in the hope that it will be useful, 8 * but WITHOUT ANY WARRANTY; without even the implied warranty of 9 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 10 * GNU General Public License for more details. 11 * 12 * You should have received a copy of the GNU General Public License 13 * along with this program; if not, write to the Free Software 14 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 15 * 02110-1301, USA. 16 */ 17 18 #include <linux/console.h> 19 #include <linux/delay.h> 20 #include <linux/err.h> 21 #include <linux/init.h> 22 #include <linux/moduleparam.h> 23 #include <linux/types.h> 24 25 #include <asm/processor.h> 26 27 #include "hvc_console.h" 28 29 /* DCC Status Bits */ 30 #define DCC_STATUS_RX (1 << 30) 31 #define DCC_STATUS_TX (1 << 29) 32 33 static inline u32 __dcc_getstatus(void) 34 { 35 u32 __ret; 36 asm volatile("mrc p14, 0, %0, c0, c1, 0 @ read comms ctrl reg" 37 : "=r" (__ret) : : "cc"); 38 39 return __ret; 40 } 41 42 43 static inline char __dcc_getchar(void) 44 { 45 char __c; 46 47 asm volatile("mrc p14, 0, %0, c0, c5, 0 @ read comms data reg" 48 : "=r" (__c)); 49 50 return __c; 51 } 52 53 static inline void __dcc_putchar(char c) 54 { 55 asm volatile("mcr p14, 0, %0, c0, c5, 0 @ write a char" 56 : /* no output register */ 57 : "r" (c)); 58 } 59 60 static int hvc_dcc_put_chars(uint32_t vt, const char *buf, int count) 61 { 62 int i; 63 64 for (i = 0; i < count; i++) { 65 while (__dcc_getstatus() & DCC_STATUS_TX) 66 cpu_relax(); 67 68 __dcc_putchar(buf[i]); 69 } 70 71 return count; 72 } 73 74 static int hvc_dcc_get_chars(uint32_t vt, char *buf, int count) 75 { 76 int i; 77 78 for (i = 0; i < count; ++i) 79 if (__dcc_getstatus() & DCC_STATUS_RX) 80 buf[i] = __dcc_getchar(); 81 else 82 break; 83 84 return i; 85 } 86 87 static const struct hv_ops hvc_dcc_get_put_ops = { 88 .get_chars = hvc_dcc_get_chars, 89 .put_chars = hvc_dcc_put_chars, 90 }; 91 92 static int __init hvc_dcc_console_init(void) 93 { 94 hvc_instantiate(0, 0, &hvc_dcc_get_put_ops); 95 return 0; 96 } 97 console_initcall(hvc_dcc_console_init); 98 99 static int __init hvc_dcc_init(void) 100 { 101 hvc_alloc(0, 0, &hvc_dcc_get_put_ops, 128); 102 return 0; 103 } 104 device_initcall(hvc_dcc_init); 105