drivers/staging/greybus/i2c.c

   1 /*
   2  * I2C bridge driver for the Greybus "generic" I2C module.
   3  *
   4  * Copyright 2014 Google Inc.
   5  * Copyright 2014 Linaro Ltd.
   6  *
   7  * Released under the GPLv2 only.
   8  */
   9
  10 #include <linux/kernel.h>
  11 #include <linux/module.h>
  12 #include <linux/slab.h>
  13 #include <linux/i2c.h>
  14
  15 #include "greybus.h"
  16 #include "gbphy.h"
  17
  18 struct gb_i2c_device {
  19         struct gb_connection    *connection;
  20         struct gbphy_device     *gbphy_dev;
  21
  22         u32                     functionality;
  23
  24         struct i2c_adapter      adapter;
  25 };
  26
  27 /*
  28  * Map Greybus i2c functionality bits into Linux ones
  29  */
  30 static u32 gb_i2c_functionality_map(u32 gb_i2c_functionality)
  31 {
  32         return gb_i2c_functionality;    /* All bits the same for now */
  33 }
  34
  35 static int gb_i2c_functionality_operation(struct gb_i2c_device *gb_i2c_dev)
  36 {
  37         struct gb_i2c_functionality_response response;
  38         u32 functionality;
  39         int ret;
  40
  41         ret = gb_operation_sync(gb_i2c_dev->connection,
  42                                 GB_I2C_TYPE_FUNCTIONALITY,
  43                                 NULL, 0, &response, sizeof(response));
  44         if (ret)
  45                 return ret;
  46
  47         functionality = le32_to_cpu(response.functionality);
  48         gb_i2c_dev->functionality = gb_i2c_functionality_map(functionality);
  49
  50         return 0;
  51 }
  52
  53 /*
  54  * Map Linux i2c_msg flags into Greybus i2c transfer op flags.
  55  */
  56 static u16 gb_i2c_transfer_op_flags_map(u16 flags)
  57 {
  58         return flags;   /* All flags the same for now */
  59 }
  60
  61 static void
  62 gb_i2c_fill_transfer_op(struct gb_i2c_transfer_op *op, struct i2c_msg *msg)
  63 {
  64         u16 flags = gb_i2c_transfer_op_flags_map(msg->flags);
  65
  66         op->addr = cpu_to_le16(msg->addr);
  67         op->flags = cpu_to_le16(flags);
  68         op->size = cpu_to_le16(msg->len);
  69 }
  70
  71 static struct gb_operation *
  72 gb_i2c_operation_create(struct gb_connection *connection,
  73                         struct i2c_msg *msgs, u32 msg_count)
  74 {
  75         struct gb_i2c_device *gb_i2c_dev = gb_connection_get_data(connection);
  76         struct gb_i2c_transfer_request *request;
  77         struct gb_operation *operation;
  78         struct gb_i2c_transfer_op *op;
  79         struct i2c_msg *msg;
  80         u32 data_out_size = 0;
  81         u32 data_in_size = 0;
  82         size_t request_size;
  83         void *data;
  84         u16 op_count;
  85         u32 i;
  86
  87         if (msg_count > (u32)U16_MAX) {
  88                 dev_err(&gb_i2c_dev->gbphy_dev->dev, "msg_count (%u) too big\n",
  89                         msg_count);
  90                 return NULL;
  91         }
  92         op_count = (u16)msg_count;
  93
  94         /*
  95          * In addition to space for all message descriptors we need
  96          * to have enough to hold all outbound message data.
  97          */
  98         msg = msgs;
  99         for (i = 0; i < msg_count; i++, msg++)
 100                 if (msg->flags & I2C_M_RD)
 101                         data_in_size += (u32)msg->len;
 102                 else
 103                         data_out_size += (u32)msg->len;
 104
 105         request_size = sizeof(*request);
 106         request_size += msg_count * sizeof(*op);
 107         request_size += data_out_size;
 108
 109         /* Response consists only of incoming data */
 110         operation = gb_operation_create(connection, GB_I2C_TYPE_TRANSFER,
 111                                 request_size, data_in_size, GFP_KERNEL);
 112         if (!operation)
 113                 return NULL;
 114
 115         request = operation->request->payload;
 116         request->op_count = cpu_to_le16(op_count);
 117         /* Fill in the ops array */
 118         op = &request->ops[0];
 119         msg = msgs;
 120         for (i = 0; i < msg_count; i++)
 121                 gb_i2c_fill_transfer_op(op++, msg++);
 122
 123         if (!data_out_size)
 124                 return operation;
 125
 126         /* Copy over the outgoing data; it starts after the last op */
 127         data = op;
 128         msg = msgs;
 129         for (i = 0; i < msg_count; i++) {
 130                 if (!(msg->flags & I2C_M_RD)) {
 131                         memcpy(data, msg->buf, msg->len);
 132                         data += msg->len;
 133                 }
 134                 msg++;
 135         }
 136
 137         return operation;
 138 }
 139
 140 static void gb_i2c_decode_response(struct i2c_msg *msgs, u32 msg_count,
 141                                 struct gb_i2c_transfer_response *response)
 142 {
 143         struct i2c_msg *msg = msgs;
 144         u8 *data;
 145         u32 i;
 146
 147         if (!response)
 148                 return;
 149         data = response->data;
 150         for (i = 0; i < msg_count; i++) {
 151                 if (msg->flags & I2C_M_RD) {
 152                         memcpy(msg->buf, data, msg->len);
 153                         data += msg->len;
 154                 }
 155                 msg++;
 156         }
 157 }
 158
 159 /*
 160  * Some i2c transfer operations return results that are expected.
 161  */
 162 static bool gb_i2c_expected_transfer_error(int errno)
 163 {
 164         return errno == -EAGAIN || errno == -ENODEV;
 165 }
 166
 167 static int gb_i2c_transfer_operation(struct gb_i2c_device *gb_i2c_dev,
 168                                         struct i2c_msg *msgs, u32 msg_count)
 169 {
 170         struct gb_connection *connection = gb_i2c_dev->connection;
 171         struct device *dev = &gb_i2c_dev->gbphy_dev->dev;
 172         struct gb_operation *operation;
 173         int ret;
 174
 175         operation = gb_i2c_operation_create(connection, msgs, msg_count);
 176         if (!operation)
 177                 return -ENOMEM;
 178
 179         ret = gbphy_runtime_get_sync(gb_i2c_dev->gbphy_dev);
 180         if (ret)
 181                 goto exit_operation_put;
 182
 183         ret = gb_operation_request_send_sync(operation);
 184         if (!ret) {
 185                 struct gb_i2c_transfer_response *response;
 186
 187                 response = operation->response->payload;
 188                 gb_i2c_decode_response(msgs, msg_count, response);
 189                 ret = msg_count;
 190         } else if (!gb_i2c_expected_transfer_error(ret)) {
 191                 dev_err(dev, "transfer operation failed (%d)\n", ret);
 192         }
 193
 194         gbphy_runtime_put_autosuspend(gb_i2c_dev->gbphy_dev);
 195
 196 exit_operation_put:
 197         gb_operation_put(operation);
 198
 199         return ret;
 200 }
 201
 202 static int gb_i2c_master_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
 203                 int msg_count)
 204 {
 205         struct gb_i2c_device *gb_i2c_dev;
 206
 207         gb_i2c_dev = i2c_get_adapdata(adap);
 208
 209         return gb_i2c_transfer_operation(gb_i2c_dev, msgs, msg_count);
 210 }
 211
 212 #if 0
 213 /* Later */
 214 static int gb_i2c_smbus_xfer(struct i2c_adapter *adap,
 215                         u16 addr, unsigned short flags, char read_write,
 216                         u8 command, int size, union i2c_smbus_data *data)
 217 {
 218         struct gb_i2c_device *gb_i2c_dev;
 219
 220         gb_i2c_dev = i2c_get_adapdata(adap);
 221
 222         return 0;
 223 }
 224 #endif
 225
 226 static u32 gb_i2c_functionality(struct i2c_adapter *adap)
 227 {
 228         struct gb_i2c_device *gb_i2c_dev = i2c_get_adapdata(adap);
 229
 230         return gb_i2c_dev->functionality;
 231 }
 232
 233 static const struct i2c_algorithm gb_i2c_algorithm = {
 234         .master_xfer    = gb_i2c_master_xfer,
 235         /* .smbus_xfer  = gb_i2c_smbus_xfer, */
 236         .functionality  = gb_i2c_functionality,
 237 };
 238
 239 /*
 240  * Do initial setup of the i2c device.  This includes verifying we
 241  * can support it (based on the protocol version it advertises).
 242  * If that's OK, we get and cached its functionality bits.
 243  *
 244  * Note: gb_i2c_dev->connection is assumed to have been valid.
 245  */
 246 static int gb_i2c_device_setup(struct gb_i2c_device *gb_i2c_dev)
 247 {
 248         /* Assume the functionality never changes, just get it once */
 249         return gb_i2c_functionality_operation(gb_i2c_dev);
 250 }
 251
 252 static int gb_i2c_probe(struct gbphy_device *gbphy_dev,
 253                          const struct gbphy_device_id *id)
 254 {
 255         struct gb_connection *connection;
 256         struct gb_i2c_device *gb_i2c_dev;
 257         struct i2c_adapter *adapter;
 258         int ret;
 259
 260         gb_i2c_dev = kzalloc(sizeof(*gb_i2c_dev), GFP_KERNEL);
 261         if (!gb_i2c_dev)
 262                 return -ENOMEM;
 263
 264         connection = gb_connection_create(gbphy_dev->bundle,
 265                                           le16_to_cpu(gbphy_dev->cport_desc->id),
 266                                           NULL);
 267         if (IS_ERR(connection)) {
 268                 ret = PTR_ERR(connection);
 269                 goto exit_i2cdev_free;
 270         }
 271
 272         gb_i2c_dev->connection = connection;
 273         gb_connection_set_data(connection, gb_i2c_dev);
 274         gb_i2c_dev->gbphy_dev = gbphy_dev;
 275         gb_gbphy_set_data(gbphy_dev, gb_i2c_dev);
 276
 277         ret = gb_connection_enable(connection);
 278         if (ret)
 279                 goto exit_connection_destroy;
 280
 281         ret = gb_i2c_device_setup(gb_i2c_dev);
 282         if (ret)
 283                 goto exit_connection_disable;
 284
 285         /* Looks good; up our i2c adapter */
 286         adapter = &gb_i2c_dev->adapter;
 287         adapter->owner = THIS_MODULE;
 288         adapter->class = I2C_CLASS_HWMON | I2C_CLASS_SPD;
 289         adapter->algo = &gb_i2c_algorithm;
 290         /* adapter->algo_data = what? */
 291
 292         adapter->dev.parent = &gbphy_dev->dev;
 293         snprintf(adapter->name, sizeof(adapter->name), "Greybus i2c adapter");
 294         i2c_set_adapdata(adapter, gb_i2c_dev);
 295
 296         ret = i2c_add_adapter(adapter);
 297         if (ret)
 298                 goto exit_connection_disable;
 299
 300         gbphy_runtime_put_autosuspend(gbphy_dev);
 301         return 0;
 302
 303 exit_connection_disable:
 304         gb_connection_disable(connection);
 305 exit_connection_destroy:
 306         gb_connection_destroy(connection);
 307 exit_i2cdev_free:
 308         kfree(gb_i2c_dev);
 309
 310         return ret;
 311 }
 312
 313 static void gb_i2c_remove(struct gbphy_device *gbphy_dev)
 314 {
 315         struct gb_i2c_device *gb_i2c_dev = gb_gbphy_get_data(gbphy_dev);
 316         struct gb_connection *connection = gb_i2c_dev->connection;
 317         int ret;
 318
 319         ret = gbphy_runtime_get_sync(gbphy_dev);
 320         if (ret)
 321                 gbphy_runtime_get_noresume(gbphy_dev);
 322
 323         i2c_del_adapter(&gb_i2c_dev->adapter);
 324         gb_connection_disable(connection);
 325         gb_connection_destroy(connection);
 326         kfree(gb_i2c_dev);
 327 }
 328
 329 static const struct gbphy_device_id gb_i2c_id_table[] = {
 330         { GBPHY_PROTOCOL(GREYBUS_PROTOCOL_I2C) },
 331         { },
 332 };
 333 MODULE_DEVICE_TABLE(gbphy, gb_i2c_id_table);
 334
 335 static struct gbphy_driver i2c_driver = {
 336         .name           = "i2c",
 337         .probe          = gb_i2c_probe,
 338         .remove         = gb_i2c_remove,
 339         .id_table       = gb_i2c_id_table,
 340 };
 341
 342 module_gbphy_driver(i2c_driver);
 343 MODULE_LICENSE("GPL v2");