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 int 36 i2c_add_adapter(struct i2c_adapter *adapter) 37 { 38 /* Linux registers a unique bus number here */ 39 return 0; 40 } 41 42 void 43 i2c_del_adapter(struct i2c_adapter *adapter) 44 { 45 /* Linux deletes a unique bus number here */ 46 } 47 48 /* 49 * i2c_transfer() 50 * The original Linux implementation does: 51 * 1. return -EOPNOTSUPP if adapter->algo->master_xfer is NULL 52 * 2. try to transfer msgs by calling adapter->algo->master_xfer() 53 * 3. if it took more ticks than adapter->timeout, fail 54 * 4. if the transfer failed, retry up to adapter->retries times 55 * 5. return the result of the last call of adapter->algo->master_xfer() 56 */ 57 int 58 i2c_transfer(struct i2c_adapter *adapter, struct i2c_msg *msgs, int num) 59 { 60 uint64_t start_ticks; 61 int ret, tries = 0; 62 63 if (adapter->algo->master_xfer == NULL) 64 return -EOPNOTSUPP; 65 66 lockmgr(&i2c_lock, LK_EXCLUSIVE); 67 start_ticks = ticks; 68 do { 69 ret = adapter->algo->master_xfer(adapter, msgs, num); 70 if (ticks > start_ticks + adapter->timeout) 71 break; 72 if (ret != -EAGAIN) 73 break; 74 tries++; 75 } while (tries < adapter->retries); 76 lockmgr(&i2c_lock, LK_RELEASE); 77 78 return ret; 79 } 80 81 static int 82 bit_xfer(struct i2c_adapter *i2c_adap, struct i2c_msg msgs[], int num) 83 { 84 /* XXX Linux really does try to transfer some data here */ 85 return 0; 86 } 87 88 static uint32_t 89 bit_func(struct i2c_adapter *adap) 90 { 91 return (I2C_FUNC_I2C | I2C_FUNC_NOSTART | I2C_FUNC_SMBUS_EMUL | 92 I2C_FUNC_SMBUS_READ_BLOCK_DATA | 93 I2C_FUNC_SMBUS_BLOCK_PROC_CALL | 94 I2C_FUNC_10BIT_ADDR | I2C_FUNC_PROTOCOL_MANGLING); 95 } 96 97 const struct i2c_algorithm i2c_bit_algo = { 98 .master_xfer = bit_xfer, 99 .functionality = bit_func, 100 }; 101 102 int 103 i2c_bit_add_bus(struct i2c_adapter *adapter) 104 { 105 adapter->algo = &i2c_bit_algo; 106 adapter->retries = 2; 107 108 return 0; 109 } 110 111 struct i2c_client * 112 i2c_new_device(struct i2c_adapter *adap, struct i2c_board_info const *info) 113 { 114 struct i2c_client *client; 115 116 client = kzalloc(sizeof(*client), GFP_KERNEL); 117 if (client == NULL) 118 goto done; 119 120 client->adapter = adap; 121 122 strlcpy(client->name, info->type, sizeof(client->name)); 123 client->addr = info->addr; 124 125 done: 126 return client; 127 } 128