Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame^] | 1 | /* ------------------------------------------------------------------------ * |
| 2 | * i2c-parport.c I2C bus over parallel port * |
| 3 | * ------------------------------------------------------------------------ * |
| 4 | Copyright (C) 2003-2004 Jean Delvare <khali@linux-fr.org> |
| 5 | |
| 6 | Based on older i2c-velleman.c driver |
| 7 | Copyright (C) 1995-2000 Simon G. Vogl |
| 8 | With some changes from: |
| 9 | Frodo Looijaard <frodol@dds.nl> |
| 10 | Kyösti Mälkki <kmalkki@cc.hut.fi> |
| 11 | |
| 12 | This program is free software; you can redistribute it and/or modify |
| 13 | it under the terms of the GNU General Public License as published by |
| 14 | the Free Software Foundation; either version 2 of the License, or |
| 15 | (at your option) any later version. |
| 16 | |
| 17 | This program is distributed in the hope that it will be useful, |
| 18 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 19 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 20 | GNU General Public License for more details. |
| 21 | |
| 22 | You should have received a copy of the GNU General Public License |
| 23 | along with this program; if not, write to the Free Software |
| 24 | Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. |
| 25 | * ------------------------------------------------------------------------ */ |
| 26 | |
| 27 | #include <linux/config.h> |
| 28 | #include <linux/kernel.h> |
| 29 | #include <linux/module.h> |
| 30 | #include <linux/init.h> |
| 31 | #include <linux/ioport.h> |
| 32 | #include <linux/i2c.h> |
| 33 | #include <linux/i2c-algo-bit.h> |
| 34 | #include <asm/io.h> |
| 35 | #include "i2c-parport.h" |
| 36 | |
| 37 | #define DEFAULT_BASE 0x378 |
| 38 | |
| 39 | static u16 base; |
| 40 | module_param(base, ushort, 0); |
| 41 | MODULE_PARM_DESC(base, "Base I/O address"); |
| 42 | |
| 43 | /* ----- Low-level parallel port access ----------------------------------- */ |
| 44 | |
| 45 | static inline void port_write(unsigned char p, unsigned char d) |
| 46 | { |
| 47 | outb(d, base+p); |
| 48 | } |
| 49 | |
| 50 | static inline unsigned char port_read(unsigned char p) |
| 51 | { |
| 52 | return inb(base+p); |
| 53 | } |
| 54 | |
| 55 | /* ----- Unified line operation functions --------------------------------- */ |
| 56 | |
| 57 | static inline void line_set(int state, const struct lineop *op) |
| 58 | { |
| 59 | u8 oldval = port_read(op->port); |
| 60 | |
| 61 | /* Touch only the bit(s) needed */ |
| 62 | if ((op->inverted && !state) || (!op->inverted && state)) |
| 63 | port_write(op->port, oldval | op->val); |
| 64 | else |
| 65 | port_write(op->port, oldval & ~op->val); |
| 66 | } |
| 67 | |
| 68 | static inline int line_get(const struct lineop *op) |
| 69 | { |
| 70 | u8 oldval = port_read(op->port); |
| 71 | |
| 72 | return ((op->inverted && (oldval & op->val) != op->val) |
| 73 | || (!op->inverted && (oldval & op->val) == op->val)); |
| 74 | } |
| 75 | |
| 76 | /* ----- I2C algorithm call-back functions and structures ----------------- */ |
| 77 | |
| 78 | static void parport_setscl(void *data, int state) |
| 79 | { |
| 80 | line_set(state, &adapter_parm[type].setscl); |
| 81 | } |
| 82 | |
| 83 | static void parport_setsda(void *data, int state) |
| 84 | { |
| 85 | line_set(state, &adapter_parm[type].setsda); |
| 86 | } |
| 87 | |
| 88 | static int parport_getscl(void *data) |
| 89 | { |
| 90 | return line_get(&adapter_parm[type].getscl); |
| 91 | } |
| 92 | |
| 93 | static int parport_getsda(void *data) |
| 94 | { |
| 95 | return line_get(&adapter_parm[type].getsda); |
| 96 | } |
| 97 | |
| 98 | /* Encapsulate the functions above in the correct structure |
| 99 | Note that getscl will be set to NULL by the attaching code for adapters |
| 100 | that cannot read SCL back */ |
| 101 | static struct i2c_algo_bit_data parport_algo_data = { |
| 102 | .setsda = parport_setsda, |
| 103 | .setscl = parport_setscl, |
| 104 | .getsda = parport_getsda, |
| 105 | .getscl = parport_getscl, |
| 106 | .udelay = 50, |
| 107 | .mdelay = 50, |
| 108 | .timeout = HZ, |
| 109 | }; |
| 110 | |
| 111 | /* ----- I2c structure ---------------------------------------------------- */ |
| 112 | |
| 113 | static struct i2c_adapter parport_adapter = { |
| 114 | .owner = THIS_MODULE, |
| 115 | .class = I2C_CLASS_HWMON, |
| 116 | .id = I2C_HW_B_LP, |
| 117 | .algo_data = &parport_algo_data, |
| 118 | .name = "Parallel port adapter (light)", |
| 119 | }; |
| 120 | |
| 121 | /* ----- Module loading, unloading and information ------------------------ */ |
| 122 | |
| 123 | static int __init i2c_parport_init(void) |
| 124 | { |
| 125 | int type_count; |
| 126 | |
| 127 | type_count = sizeof(adapter_parm)/sizeof(struct adapter_parm); |
| 128 | if (type < 0 || type >= type_count) { |
| 129 | printk(KERN_WARNING "i2c-parport: invalid type (%d)\n", type); |
| 130 | type = 0; |
| 131 | } |
| 132 | |
| 133 | if (base == 0) { |
| 134 | printk(KERN_INFO "i2c-parport: using default base 0x%x\n", DEFAULT_BASE); |
| 135 | base = DEFAULT_BASE; |
| 136 | } |
| 137 | |
| 138 | if (!request_region(base, 3, "i2c-parport")) |
| 139 | return -ENODEV; |
| 140 | |
| 141 | if (!adapter_parm[type].getscl.val) |
| 142 | parport_algo_data.getscl = NULL; |
| 143 | |
| 144 | /* Reset hardware to a sane state (SCL and SDA high) */ |
| 145 | parport_setsda(NULL, 1); |
| 146 | parport_setscl(NULL, 1); |
| 147 | /* Other init if needed (power on...) */ |
| 148 | if (adapter_parm[type].init.val) |
| 149 | line_set(1, &adapter_parm[type].init); |
| 150 | |
| 151 | if (i2c_bit_add_bus(&parport_adapter) < 0) { |
| 152 | printk(KERN_ERR "i2c-parport: Unable to register with I2C\n"); |
| 153 | release_region(base, 3); |
| 154 | return -ENODEV; |
| 155 | } |
| 156 | |
| 157 | return 0; |
| 158 | } |
| 159 | |
| 160 | static void __exit i2c_parport_exit(void) |
| 161 | { |
| 162 | /* Un-init if needed (power off...) */ |
| 163 | if (adapter_parm[type].init.val) |
| 164 | line_set(0, &adapter_parm[type].init); |
| 165 | |
| 166 | i2c_bit_del_bus(&parport_adapter); |
| 167 | release_region(base, 3); |
| 168 | } |
| 169 | |
| 170 | MODULE_AUTHOR("Jean Delvare <khali@linux-fr.org>"); |
| 171 | MODULE_DESCRIPTION("I2C bus over parallel port (light)"); |
| 172 | MODULE_LICENSE("GPL"); |
| 173 | |
| 174 | module_init(i2c_parport_init); |
| 175 | module_exit(i2c_parport_exit); |