drivers/staging/greybus/i2c.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * I2C bridge driver for the Greybus "generic" I2C module.
   4  *
   5  * Copyright 2014 Google Inc.
   6  * Copyright 2014 Linaro Ltd.
   7  */
   8
   9 #include <linux/kernel.h>
  10 #include <linux/module.h>
  11 #include <linux/slab.h>
  12 #include <linux/i2c.h>
  13 #include <linux/greybus.h>
  14
  15 #include "gbphy.h"
  16
  17 struct gb_i2c_device {
  18         struct gb_connection    *connection;
  19         struct gbphy_device     *gbphy_dev;
  20
  21         u32                     functionality;
  22
  23         struct i2c_adapter      adapter;
  24 };
  25
  26 /*
  27  * Map Greybus i2c functionality bits into Linux ones
  28  */
  29 static u32 gb_i2c_functionality_map(u32 gb_i2c_functionality)
  30 {
  31         return gb_i2c_functionality;    /* All bits the same for now */
  32 }
  33
  34 /*
  35  * Do initial setup of the i2c device.  This includes verifying we
  36  * can support it (based on the protocol version it advertises).
  37  * If that's OK, we get and cached its functionality bits.
  38  *
  39  * Note: gb_i2c_dev->connection is assumed to have been valid.
  40  */
  41 static int gb_i2c_device_setup(struct gb_i2c_device *gb_i2c_dev)
  42 {
  43         struct gb_i2c_functionality_response response;
  44         u32 functionality;
  45         int ret;
  46
  47         ret = gb_operation_sync(gb_i2c_dev->connection,
  48                                 GB_I2C_TYPE_FUNCTIONALITY,
  49                                 NULL, 0, &response, sizeof(response));
  50         if (ret)
  51                 return ret;
  52
  53         functionality = le32_to_cpu(response.functionality);
  54         gb_i2c_dev->functionality = gb_i2c_functionality_map(functionality);
  55
  56         return 0;
  57 }
  58
  59 /*
  60  * Map Linux i2c_msg flags into Greybus i2c transfer op flags.
  61  */
  62 static u16 gb_i2c_transfer_op_flags_map(u16 flags)
  63 {
  64         return flags;   /* All flags the same for now */
  65 }
  66
  67 static void
  68 gb_i2c_fill_transfer_op(struct gb_i2c_transfer_op *op, struct i2c_msg *msg)
  69 {
  70         u16 flags = gb_i2c_transfer_op_flags_map(msg->flags);
  71
  72         op->addr = cpu_to_le16(msg->addr);
  73         op->flags = cpu_to_le16(flags);
  74         op->size = cpu_to_le16(msg->len);
  75 }
  76
  77 static struct gb_operation *
  78 gb_i2c_operation_create(struct gb_connection *connection,
  79                         struct i2c_msg *msgs, u32 msg_count)
  80 {
  81         struct gb_i2c_device *gb_i2c_dev = gb_connection_get_data(connection);
  82         struct gb_i2c_transfer_request *request;
  83         struct gb_operation *operation;
  84         struct gb_i2c_transfer_op *op;
  85         struct i2c_msg *msg;
  86         u32 data_out_size = 0;
  87         u32 data_in_size = 0;
  88         size_t request_size;
  89         void *data;
  90         u16 op_count;
  91         u32 i;
  92
  93         if (msg_count > (u32)U16_MAX) {
  94                 dev_err(&gb_i2c_dev->gbphy_dev->dev, "msg_count (%u) too big\n",
  95                         msg_count);
  96                 return NULL;
  97         }
  98         op_count = (u16)msg_count;
  99
 100         /*
 101          * In addition to space for all message descriptors we need
 102          * to have enough to hold all outbound message data.
 103          */
 104         msg = msgs;
 105         for (i = 0; i < msg_count; i++, msg++)
 106                 if (msg->flags & I2C_M_RD)
 107                         data_in_size += (u32)msg->len;
 108                 else
 109                         data_out_size += (u32)msg->len;
 110
 111         request_size = sizeof(*request);
 112         request_size += msg_count * sizeof(*op);
 113         request_size += data_out_size;
 114
 115         /* Response consists only of incoming data */
 116         operation = gb_operation_create(connection, GB_I2C_TYPE_TRANSFER,
 117                                         request_size, data_in_size, GFP_KERNEL);
 118         if (!operation)
 119                 return NULL;
 120
 121         request = operation->request->payload;
 122         request->op_count = cpu_to_le16(op_count);
 123         /* Fill in the ops array */
 124         op = &request->ops[0];
 125         msg = msgs;
 126         for (i = 0; i < msg_count; i++)
 127                 gb_i2c_fill_transfer_op(op++, msg++);
 128
 129         if (!data_out_size)
 130                 return operation;
 131
 132         /* Copy over the outgoing data; it starts after the last op */
 133         data = op;
 134         msg = msgs;
 135         for (i = 0; i < msg_count; i++) {
 136                 if (!(msg->flags & I2C_M_RD)) {
 137                         memcpy(data, msg->buf, msg->len);
 138                         data += msg->len;
 139                 }
 140                 msg++;
 141         }
 142
 143         return operation;
 144 }
 145
 146 static void gb_i2c_decode_response(struct i2c_msg *msgs, u32 msg_count,
 147                                    struct gb_i2c_transfer_response *response)
 148 {
 149         struct i2c_msg *msg = msgs;
 150         u8 *data;
 151         u32 i;
 152
 153         if (!response)
 154                 return;
 155         data = response->data;
 156         for (i = 0; i < msg_count; i++) {
 157                 if (msg->flags & I2C_M_RD) {
 158                         memcpy(msg->buf, data, msg->len);
 159                         data += msg->len;
 160                 }
 161                 msg++;
 162         }
 163 }
 164
 165 /*
 166  * Some i2c transfer operations return results that are expected.
 167  */
 168 static bool gb_i2c_expected_transfer_error(int errno)
 169 {
 170         return errno == -EAGAIN || errno == -ENODEV;
 171 }
 172
 173 static int gb_i2c_transfer_operation(struct gb_i2c_device *gb_i2c_dev,
 174                                      struct i2c_msg *msgs, u32 msg_count)
 175 {
 176         struct gb_connection *connection = gb_i2c_dev->connection;
 177         struct device *dev = &gb_i2c_dev->gbphy_dev->dev;
 178         struct gb_operation *operation;
 179         int ret;
 180
 181         operation = gb_i2c_operation_create(connection, msgs, msg_count);
 182         if (!operation)
 183                 return -ENOMEM;
 184
 185         ret = gbphy_runtime_get_sync(gb_i2c_dev->gbphy_dev);
 186         if (ret)
 187                 goto exit_operation_put;
 188
 189         ret = gb_operation_request_send_sync(operation);
 190         if (!ret) {
 191                 struct gb_i2c_transfer_response *response;
 192
 193                 response = operation->response->payload;
 194                 gb_i2c_decode_response(msgs, msg_count, response);
 195                 ret = msg_count;
 196         } else if (!gb_i2c_expected_transfer_error(ret)) {
 197                 dev_err(dev, "transfer operation failed (%d)\n", ret);
 198         }
 199
 200         gbphy_runtime_put_autosuspend(gb_i2c_dev->gbphy_dev);
 201
 202 exit_operation_put:
 203         gb_operation_put(operation);
 204
 205         return ret;
 206 }
 207
 208 static int gb_i2c_master_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
 209                               int msg_count)
 210 {
 211         struct gb_i2c_device *gb_i2c_dev;
 212
 213         gb_i2c_dev = i2c_get_adapdata(adap);
 214
 215         return gb_i2c_transfer_operation(gb_i2c_dev, msgs, msg_count);
 216 }
 217
 218 static u32 gb_i2c_functionality(struct i2c_adapter *adap)
 219 {
 220         struct gb_i2c_device *gb_i2c_dev = i2c_get_adapdata(adap);
 221
 222         return gb_i2c_dev->functionality;
 223 }
 224
 225 static const struct i2c_algorithm gb_i2c_algorithm = {
 226         .master_xfer    = gb_i2c_master_xfer,
 227         .functionality  = gb_i2c_functionality,
 228 };
 229
 230 static int gb_i2c_probe(struct gbphy_device *gbphy_dev,
 231                         const struct gbphy_device_id *id)
 232 {
 233         struct gb_connection *connection;
 234         struct gb_i2c_device *gb_i2c_dev;
 235         struct i2c_adapter *adapter;
 236         int ret;
 237
 238         gb_i2c_dev = kzalloc(sizeof(*gb_i2c_dev), GFP_KERNEL);
 239         if (!gb_i2c_dev)
 240                 return -ENOMEM;
 241
 242         connection =
 243                 gb_connection_create(gbphy_dev->bundle,
 244                                      le16_to_cpu(gbphy_dev->cport_desc->id),
 245                                      NULL);
 246         if (IS_ERR(connection)) {
 247                 ret = PTR_ERR(connection);
 248                 goto exit_i2cdev_free;
 249         }
 250
 251         gb_i2c_dev->connection = connection;
 252         gb_connection_set_data(connection, gb_i2c_dev);
 253         gb_i2c_dev->gbphy_dev = gbphy_dev;
 254         gb_gbphy_set_data(gbphy_dev, gb_i2c_dev);
 255
 256         ret = gb_connection_enable(connection);
 257         if (ret)
 258                 goto exit_connection_destroy;
 259
 260         ret = gb_i2c_device_setup(gb_i2c_dev);
 261         if (ret)
 262                 goto exit_connection_disable;
 263
 264         /* Looks good; up our i2c adapter */
 265         adapter = &gb_i2c_dev->adapter;
 266         adapter->owner = THIS_MODULE;
 267         adapter->class = I2C_CLASS_HWMON | I2C_CLASS_SPD;
 268         adapter->algo = &gb_i2c_algorithm;
 269
 270         adapter->dev.parent = &gbphy_dev->dev;
 271         snprintf(adapter->name, sizeof(adapter->name), "Greybus i2c adapter");
 272         i2c_set_adapdata(adapter, gb_i2c_dev);
 273
 274         ret = i2c_add_adapter(adapter);
 275         if (ret)
 276                 goto exit_connection_disable;
 277
 278         gbphy_runtime_put_autosuspend(gbphy_dev);
 279         return 0;
 280
 281 exit_connection_disable:
 282         gb_connection_disable(connection);
 283 exit_connection_destroy:
 284         gb_connection_destroy(connection);
 285 exit_i2cdev_free:
 286         kfree(gb_i2c_dev);
 287
 288         return ret;
 289 }
 290
 291 static void gb_i2c_remove(struct gbphy_device *gbphy_dev)
 292 {
 293         struct gb_i2c_device *gb_i2c_dev = gb_gbphy_get_data(gbphy_dev);
 294         struct gb_connection *connection = gb_i2c_dev->connection;
 295         int ret;
 296
 297         ret = gbphy_runtime_get_sync(gbphy_dev);
 298         if (ret)
 299                 gbphy_runtime_get_noresume(gbphy_dev);
 300
 301         i2c_del_adapter(&gb_i2c_dev->adapter);
 302         gb_connection_disable(connection);
 303         gb_connection_destroy(connection);
 304         kfree(gb_i2c_dev);
 305 }
 306
 307 static const struct gbphy_device_id gb_i2c_id_table[] = {
 308         { GBPHY_PROTOCOL(GREYBUS_PROTOCOL_I2C) },
 309         { },
 310 };
 311 MODULE_DEVICE_TABLE(gbphy, gb_i2c_id_table);
 312
 313 static struct gbphy_driver i2c_driver = {
 314         .name           = "i2c",
 315         .probe          = gb_i2c_probe,
 316         .remove         = gb_i2c_remove,
 317         .id_table       = gb_i2c_id_table,
 318 };
 319
 320 module_gbphy_driver(i2c_driver);
 321 MODULE_LICENSE("GPL v2");