drivers/i2c/busses/i2c-tegra-bpmp.c

   1 /*
   2  * drivers/i2c/busses/i2c-tegra-bpmp.c
   3  *
   4  * Copyright (c) 2016 NVIDIA Corporation.  All rights reserved.
   5  *
   6  * Author: Shardar Shariff Md <smohammed@nvidia.com>
   7  *
   8  * This program is free software; you can redistribute it and/or modify it
   9  * under the terms and conditions of the GNU General Public License,
  10  * version 2, as published by the Free Software Foundation.
  11  *
  12  * This program is distributed in the hope it will be useful, but WITHOUT
  13  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  15  * more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  19  */
  20
  21 #include <linux/err.h>
  22 #include <linux/i2c.h>
  23 #include <linux/init.h>
  24 #include <linux/kernel.h>
  25 #include <linux/module.h>
  26 #include <linux/of_device.h>
  27 #include <linux/platform_device.h>
  28 #include <linux/pm_runtime.h>
  29
  30 #include <soc/tegra/bpmp-abi.h>
  31 #include <soc/tegra/bpmp.h>
  32
  33 /*
  34  * Serialized I2C message header size is 6 bytes and includes address, flags
  35  * and length
  36  */
  37 #define SERIALI2C_HDR_SIZE 6
  38
  39 struct tegra_bpmp_i2c {
  40         struct i2c_adapter adapter;
  41         struct device *dev;
  42
  43         struct tegra_bpmp *bpmp;
  44         unsigned int bus;
  45 };
  46
  47 /*
  48  * Linux flags are translated to BPMP defined I2C flags that are used in BPMP
  49  * firmware I2C driver to avoid any issues in future if Linux I2C flags are
  50  * changed.
  51  */
  52 static int tegra_bpmp_xlate_flags(u16 flags, u16 *out)
  53 {
  54         if (flags & I2C_M_TEN) {
  55                 *out |= SERIALI2C_TEN;
  56                 flags &= ~I2C_M_TEN;
  57         }
  58
  59         if (flags & I2C_M_RD) {
  60                 *out |= SERIALI2C_RD;
  61                 flags &= ~I2C_M_RD;
  62         }
  63
  64         if (flags & I2C_M_STOP) {
  65                 *out |= SERIALI2C_STOP;
  66                 flags &= ~I2C_M_STOP;
  67         }
  68
  69         if (flags & I2C_M_NOSTART) {
  70                 *out |= SERIALI2C_NOSTART;
  71                 flags &= ~I2C_M_NOSTART;
  72         }
  73
  74         if (flags & I2C_M_REV_DIR_ADDR) {
  75                 *out |= SERIALI2C_REV_DIR_ADDR;
  76                 flags &= ~I2C_M_REV_DIR_ADDR;
  77         }
  78
  79         if (flags & I2C_M_IGNORE_NAK) {
  80                 *out |= SERIALI2C_IGNORE_NAK;
  81                 flags &= ~I2C_M_IGNORE_NAK;
  82         }
  83
  84         if (flags & I2C_M_NO_RD_ACK) {
  85                 *out |= SERIALI2C_NO_RD_ACK;
  86                 flags &= ~I2C_M_NO_RD_ACK;
  87         }
  88
  89         if (flags & I2C_M_RECV_LEN) {
  90                 *out |= SERIALI2C_RECV_LEN;
  91                 flags &= ~I2C_M_RECV_LEN;
  92         }
  93
  94         return (flags != 0) ? -EINVAL : 0;
  95 }
  96
  97 /**
  98  * The serialized I2C format is simply the following:
  99  * [addr little-endian][flags little-endian][len little-endian][data if write]
 100  * [addr little-endian][flags little-endian][len little-endian][data if write]
 101  *  ...
 102  *
 103  * The flags are translated from Linux kernel representation to seriali2c
 104  * representation. Any undefined flag being set causes an error.
 105  *
 106  * The data is there only for writes. Reads have the data transferred in the
 107  * other direction, and thus data is not present.
 108  *
 109  * See deserialize_i2c documentation for the data format in the other direction.
 110  */
 111 static int tegra_bpmp_serialize_i2c_msg(struct tegra_bpmp_i2c *i2c,
 112                                         struct mrq_i2c_request *request,
 113                                         struct i2c_msg *msgs,
 114                                         unsigned int num)
 115 {
 116         char *buf = request->xfer.data_buf;
 117         unsigned int i, j, pos = 0;
 118         int err;
 119
 120         for (i = 0; i < num; i++) {
 121                 struct i2c_msg *msg = &msgs[i];
 122                 u16 flags = 0;
 123
 124                 err = tegra_bpmp_xlate_flags(msg->flags, &flags);
 125                 if (err < 0)
 126                         return err;
 127
 128                 buf[pos++] = msg->addr & 0xff;
 129                 buf[pos++] = (msg->addr & 0xff00) >> 8;
 130                 buf[pos++] = flags & 0xff;
 131                 buf[pos++] = (flags & 0xff00) >> 8;
 132                 buf[pos++] = msg->len & 0xff;
 133                 buf[pos++] = (msg->len & 0xff00) >> 8;
 134
 135                 if ((flags & SERIALI2C_RD) == 0) {
 136                         for (j = 0; j < msg->len; j++)
 137                                 buf[pos++] = msg->buf[j];
 138                 }
 139         }
 140
 141         request->xfer.data_size = pos;
 142
 143         return 0;
 144 }
 145
 146 /**
 147  * The data in the BPMP -> CPU direction is composed of sequential blocks for
 148  * those messages that have I2C_M_RD. So, for example, if you have:
 149  *
 150  * - !I2C_M_RD, len == 5, data == a0 01 02 03 04
 151  * - !I2C_M_RD, len == 1, data == a0
 152  * - I2C_M_RD, len == 2, data == [uninitialized buffer 1]
 153  * - !I2C_M_RD, len == 1, data == a2
 154  * - I2C_M_RD, len == 2, data == [uninitialized buffer 2]
 155  *
 156  * ...then the data in the BPMP -> CPU direction would be 4 bytes total, and
 157  * would contain 2 bytes that will go to uninitialized buffer 1, and 2 bytes
 158  * that will go to uninitialized buffer 2.
 159  */
 160 static int tegra_bpmp_i2c_deserialize(struct tegra_bpmp_i2c *i2c,
 161                                       struct mrq_i2c_response *response,
 162                                       struct i2c_msg *msgs,
 163                                       unsigned int num)
 164 {
 165         size_t size = response->xfer.data_size, len = 0, pos = 0;
 166         char *buf = response->xfer.data_buf;
 167         unsigned int i;
 168
 169         for (i = 0; i < num; i++)
 170                 if (msgs[i].flags & I2C_M_RD)
 171                         len += msgs[i].len;
 172
 173         if (len != size)
 174                 return -EINVAL;
 175
 176         for (i = 0; i < num; i++) {
 177                 if (msgs[i].flags & I2C_M_RD) {
 178                         memcpy(msgs[i].buf, buf + pos, msgs[i].len);
 179                         pos += msgs[i].len;
 180                 }
 181         }
 182
 183         return 0;
 184 }
 185
 186 static int tegra_bpmp_i2c_msg_len_check(struct i2c_msg *msgs, unsigned int num)
 187 {
 188         size_t tx_len = 0, rx_len = 0;
 189         unsigned int i;
 190
 191         for (i = 0; i < num; i++)
 192                 if (!(msgs[i].flags & I2C_M_RD))
 193                         tx_len += SERIALI2C_HDR_SIZE + msgs[i].len;
 194
 195         if (tx_len > TEGRA_I2C_IPC_MAX_IN_BUF_SIZE)
 196                 return -EINVAL;
 197
 198         for (i = 0; i < num; i++)
 199                 if ((msgs[i].flags & I2C_M_RD))
 200                         rx_len += msgs[i].len;
 201
 202         if (rx_len > TEGRA_I2C_IPC_MAX_OUT_BUF_SIZE)
 203                 return -EINVAL;
 204
 205         return 0;
 206 }
 207
 208 static int tegra_bpmp_i2c_msg_xfer(struct tegra_bpmp_i2c *i2c,
 209                                    struct mrq_i2c_request *request,
 210                                    struct mrq_i2c_response *response)
 211 {
 212         struct tegra_bpmp_message msg;
 213         int err;
 214
 215         request->cmd = CMD_I2C_XFER;
 216         request->xfer.bus_id = i2c->bus;
 217
 218         memset(&msg, 0, sizeof(msg));
 219         msg.mrq = MRQ_I2C;
 220         msg.tx.data = request;
 221         msg.tx.size = sizeof(*request);
 222         msg.rx.data = response;
 223         msg.rx.size = sizeof(*response);
 224
 225         if (irqs_disabled())
 226                 err = tegra_bpmp_transfer_atomic(i2c->bpmp, &msg);
 227         else
 228                 err = tegra_bpmp_transfer(i2c->bpmp, &msg);
 229
 230         return err;
 231 }
 232
 233 static int tegra_bpmp_i2c_xfer(struct i2c_adapter *adapter,
 234                                struct i2c_msg *msgs, int num)
 235 {
 236         struct tegra_bpmp_i2c *i2c = i2c_get_adapdata(adapter);
 237         struct mrq_i2c_response response;
 238         struct mrq_i2c_request request;
 239         int err;
 240
 241         err = tegra_bpmp_i2c_msg_len_check(msgs, num);
 242         if (err < 0) {
 243                 dev_err(i2c->dev, "unsupported message length\n");
 244                 return err;
 245         }
 246
 247         memset(&request, 0, sizeof(request));
 248         memset(&response, 0, sizeof(response));
 249
 250         err = tegra_bpmp_serialize_i2c_msg(i2c, &request, msgs, num);
 251         if (err < 0) {
 252                 dev_err(i2c->dev, "failed to serialize message: %d\n", err);
 253                 return err;
 254         }
 255
 256         err = tegra_bpmp_i2c_msg_xfer(i2c, &request, &response);
 257         if (err < 0) {
 258                 dev_err(i2c->dev, "failed to transfer message: %d\n", err);
 259                 return err;
 260         }
 261
 262         err = tegra_bpmp_i2c_deserialize(i2c, &response, msgs, num);
 263         if (err < 0) {
 264                 dev_err(i2c->dev, "failed to deserialize message: %d\n", err);
 265                 return err;
 266         }
 267
 268         return num;
 269 }
 270
 271 static u32 tegra_bpmp_i2c_func(struct i2c_adapter *adapter)
 272 {
 273         return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_10BIT_ADDR |
 274                I2C_FUNC_PROTOCOL_MANGLING | I2C_FUNC_NOSTART;
 275 }
 276
 277 static const struct i2c_algorithm tegra_bpmp_i2c_algo = {
 278         .master_xfer = tegra_bpmp_i2c_xfer,
 279         .functionality = tegra_bpmp_i2c_func,
 280 };
 281
 282 static int tegra_bpmp_i2c_probe(struct platform_device *pdev)
 283 {
 284         struct tegra_bpmp_i2c *i2c;
 285         u32 value;
 286         int err;
 287
 288         i2c = devm_kzalloc(&pdev->dev, sizeof(*i2c), GFP_KERNEL);
 289         if (!i2c)
 290                 return -ENOMEM;
 291
 292         i2c->dev = &pdev->dev;
 293
 294         i2c->bpmp = dev_get_drvdata(pdev->dev.parent);
 295         if (!i2c->bpmp)
 296                 return -ENODEV;
 297
 298         err = of_property_read_u32(pdev->dev.of_node, "nvidia,bpmp-bus-id",
 299                                    &value);
 300         if (err < 0)
 301                 return err;
 302
 303         i2c->bus = value;
 304
 305         i2c_set_adapdata(&i2c->adapter, i2c);
 306         i2c->adapter.owner = THIS_MODULE;
 307         strlcpy(i2c->adapter.name, "Tegra BPMP I2C adapter",
 308                 sizeof(i2c->adapter.name));
 309         i2c->adapter.algo = &tegra_bpmp_i2c_algo;
 310         i2c->adapter.dev.parent = &pdev->dev;
 311         i2c->adapter.dev.of_node = pdev->dev.of_node;
 312
 313         platform_set_drvdata(pdev, i2c);
 314
 315         return i2c_add_adapter(&i2c->adapter);
 316 }
 317
 318 static int tegra_bpmp_i2c_remove(struct platform_device *pdev)
 319 {
 320         struct tegra_bpmp_i2c *i2c = platform_get_drvdata(pdev);
 321
 322         i2c_del_adapter(&i2c->adapter);
 323
 324         return 0;
 325 }
 326
 327 static const struct of_device_id tegra_bpmp_i2c_of_match[] = {
 328         { .compatible = "nvidia,tegra186-bpmp-i2c", },
 329         { }
 330 };
 331 MODULE_DEVICE_TABLE(of, tegra_bpmp_i2c_of_match);
 332
 333 static struct platform_driver tegra_bpmp_i2c_driver = {
 334         .driver = {
 335                 .name = "tegra-bpmp-i2c",
 336                 .of_match_table = tegra_bpmp_i2c_of_match,
 337         },
 338         .probe = tegra_bpmp_i2c_probe,
 339         .remove = tegra_bpmp_i2c_remove,
 340 };
 341 module_platform_driver(tegra_bpmp_i2c_driver);
 342
 343 MODULE_DESCRIPTION("NVIDIA Tegra BPMP I2C bus controller driver");
 344 MODULE_AUTHOR("Shardar Shariff Md <smohammed@nvidia.com>");
 345 MODULE_AUTHOR("Juha-Matti Tilli");
 346 MODULE_LICENSE("GPL v2");