1 /* 2 * Copyright (c) 2016-2019 François Tigeot <ftigeot@wolfpond.org> 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice unmodified, this list of conditions, and the following 10 * disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 */ 26 27 #include <linux/i2c.h> 28 #include <linux/i2c-algo-bit.h> 29 30 #include <linux/slab.h> 31 32 static struct lock i2c_lock; 33 LOCK_SYSINIT(i2c_lock, &i2c_lock, "i2cl", LK_CANRECURSE); 34 35 static void i2c_default_lock_bus(struct i2c_adapter *, unsigned int); 36 static int i2c_default_trylock_bus(struct i2c_adapter *, unsigned int); 37 static void i2c_default_unlock_bus(struct i2c_adapter *, unsigned int); 38 39 static const struct i2c_lock_operations i2c_default_lock_ops = { 40 .lock_bus = i2c_default_lock_bus, 41 .trylock_bus = i2c_default_trylock_bus, 42 .unlock_bus = i2c_default_unlock_bus, 43 }; 44 45 int 46 i2c_add_adapter(struct i2c_adapter *adapter) 47 { 48 /* Linux registers a unique bus number here */ 49 50 /* Setup default locking functions */ 51 if (!adapter->lock_ops) 52 adapter->lock_ops = &i2c_default_lock_ops; 53 54 return 0; 55 } 56 57 void 58 i2c_del_adapter(struct i2c_adapter *adapter) 59 { 60 /* Linux deletes a unique bus number here */ 61 } 62 63 /* 64 * i2c_transfer() 65 * The original Linux implementation does: 66 * 1. return -EOPNOTSUPP if adapter->algo->master_xfer is NULL 67 * 2. try to transfer msgs by calling adapter->algo->master_xfer() 68 * 3. if it took more ticks than adapter->timeout, fail 69 * 4. if the transfer failed, retry up to adapter->retries times 70 * 5. return the result of the last call of adapter->algo->master_xfer() 71 */ 72 int 73 i2c_transfer(struct i2c_adapter *adapter, struct i2c_msg *msgs, int num) 74 { 75 uint64_t start_ticks; 76 int ret, tries = 0; 77 78 if (adapter->algo->master_xfer == NULL) 79 return -EOPNOTSUPP; 80 81 adapter->lock_ops->lock_bus(adapter, I2C_LOCK_SEGMENT); 82 start_ticks = ticks; 83 do { 84 ret = adapter->algo->master_xfer(adapter, msgs, num); 85 if (ticks > start_ticks + adapter->timeout) 86 break; 87 if (ret != -EAGAIN) 88 break; 89 tries++; 90 } while (tries < adapter->retries); 91 adapter->lock_ops->unlock_bus(adapter, I2C_LOCK_SEGMENT); 92 93 return ret; 94 } 95 96 static int 97 bit_xfer(struct i2c_adapter *i2c_adap, struct i2c_msg msgs[], int num) 98 { 99 /* XXX Linux really does try to transfer some data here */ 100 return 0; 101 } 102 103 static uint32_t 104 bit_func(struct i2c_adapter *adap) 105 { 106 return (I2C_FUNC_I2C | I2C_FUNC_NOSTART | I2C_FUNC_SMBUS_EMUL | 107 I2C_FUNC_SMBUS_READ_BLOCK_DATA | 108 I2C_FUNC_SMBUS_BLOCK_PROC_CALL | 109 I2C_FUNC_10BIT_ADDR | I2C_FUNC_PROTOCOL_MANGLING); 110 } 111 112 const struct i2c_algorithm i2c_bit_algo = { 113 .master_xfer = bit_xfer, 114 .functionality = bit_func, 115 }; 116 117 int 118 i2c_bit_add_bus(struct i2c_adapter *adapter) 119 { 120 adapter->algo = &i2c_bit_algo; 121 adapter->retries = 2; 122 123 return 0; 124 } 125 126 struct i2c_client * 127 i2c_new_device(struct i2c_adapter *adap, struct i2c_board_info const *info) 128 { 129 struct i2c_client *client; 130 131 client = kzalloc(sizeof(*client), GFP_KERNEL); 132 if (client == NULL) 133 goto done; 134 135 client->adapter = adap; 136 137 strlcpy(client->name, info->type, sizeof(client->name)); 138 client->addr = info->addr; 139 140 done: 141 return client; 142 } 143 144 /* Default locking functions */ 145 146 static void 147 i2c_default_lock_bus(struct i2c_adapter *adapter, unsigned int flags) 148 { 149 lockmgr(&i2c_lock, LK_EXCLUSIVE); 150 } 151 152 static int 153 i2c_default_trylock_bus(struct i2c_adapter *adapter, unsigned int flags) 154 { 155 return mutex_trylock(&i2c_lock); 156 } 157 158 static void 159 i2c_default_unlock_bus(struct i2c_adapter *adapter, unsigned int flags) 160 { 161 lockmgr(&i2c_lock, LK_RELEASE); 162 } 163