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 37 asm("mrc p14, 0, %0, c0, c1, 0 @ read comms ctrl reg" 38 : "=r" (__ret) : : "cc"); 39 40 return __ret; 41 } 42 43 44 #if defined(CONFIG_CPU_V7) 45 static inline char __dcc_getchar(void) 46 { 47 char __c; 48 49 asm("get_wait: mrc p14, 0, pc, c0, c1, 0 \n\ 50 bne get_wait \n\ 51 mrc p14, 0, %0, c0, c5, 0 @ read comms data reg" 52 : "=r" (__c) : : "cc"); 53 54 return __c; 55 } 56 #else 57 static inline char __dcc_getchar(void) 58 { 59 char __c; 60 61 asm("mrc p14, 0, %0, c0, c5, 0 @ read comms data reg" 62 : "=r" (__c)); 63 64 return __c; 65 } 66 #endif 67 68 #if defined(CONFIG_CPU_V7) 69 static inline void __dcc_putchar(char c) 70 { 71 asm("put_wait: mrc p14, 0, pc, c0, c1, 0 \n\ 72 bcs put_wait \n\ 73 mcr p14, 0, %0, c0, c5, 0 " 74 : : "r" (c) : "cc"); 75 } 76 #else 77 static inline void __dcc_putchar(char c) 78 { 79 asm("mcr p14, 0, %0, c0, c5, 0 @ write a char" 80 : /* no output register */ 81 : "r" (c)); 82 } 83 #endif 84 85 static int hvc_dcc_put_chars(uint32_t vt, const char *buf, int count) 86 { 87 int i; 88 89 for (i = 0; i < count; i++) { 90 while (__dcc_getstatus() & DCC_STATUS_TX) 91 cpu_relax(); 92 93 __dcc_putchar((char)(buf[i] & 0xFF)); 94 } 95 96 return count; 97 } 98 99 static int hvc_dcc_get_chars(uint32_t vt, char *buf, int count) 100 { 101 int i; 102 103 for (i = 0; i < count; ++i) { 104 int c = -1; 105 106 if (__dcc_getstatus() & DCC_STATUS_RX) 107 c = __dcc_getchar(); 108 if (c < 0) 109 break; 110 buf[i] = c; 111 } 112 113 return i; 114 } 115 116 static const struct hv_ops hvc_dcc_get_put_ops = { 117 .get_chars = hvc_dcc_get_chars, 118 .put_chars = hvc_dcc_put_chars, 119 }; 120 121 static int __init hvc_dcc_console_init(void) 122 { 123 hvc_instantiate(0, 0, &hvc_dcc_get_put_ops); 124 return 0; 125 } 126 console_initcall(hvc_dcc_console_init); 127 128 static int __init hvc_dcc_init(void) 129 { 130 hvc_alloc(0, 0, &hvc_dcc_get_put_ops, 128); 131 return 0; 132 } 133 device_initcall(hvc_dcc_init); 134