include/drm/drm_dp_helper.h

   1 /*
   2  * Copyright © 2008 Keith Packard
   3  *
   4  * Permission to use, copy, modify, distribute, and sell this software and its
   5  * documentation for any purpose is hereby granted without fee, provided that
   6  * the above copyright notice appear in all copies and that both that copyright
   7  * notice and this permission notice appear in supporting documentation, and
   8  * that the name of the copyright holders not be used in advertising or
   9  * publicity pertaining to distribution of the software without specific,
  10  * written prior permission.  The copyright holders make no representations
  11  * about the suitability of this software for any purpose.  It is provided "as
  12  * is" without express or implied warranty.
  13  *
  14  * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
  15  * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
  16  * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
  17  * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
  18  * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
  19  * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
  20  * OF THIS SOFTWARE.
  21  */
  22
  23 #ifndef _DRM_DP_HELPER_H_
  24 #define _DRM_DP_HELPER_H_
  25
  26 #include <linux/types.h>
  27 #include <linux/i2c.h>
  28 #include <linux/delay.h>
  29
  30 /*
  31  * Unless otherwise noted, all values are from the DP 1.1a spec.  Note that
  32  * DP and DPCD versions are independent.  Differences from 1.0 are not noted,
  33  * 1.0 devices basically don't exist in the wild.
  34  *
  35  * Abbreviations, in chronological order:
  36  *
  37  * eDP: Embedded DisplayPort version 1
  38  * DPI: DisplayPort Interoperability Guideline v1.1a
  39  * 1.2: DisplayPort 1.2
  40  *
  41  * 1.2 formally includes both eDP and DPI definitions.
  42  */
  43
  44 #define DP_AUX_I2C_WRITE                0x0
  45 #define DP_AUX_I2C_READ                 0x1
  46 #define DP_AUX_I2C_STATUS               0x2
  47 #define DP_AUX_I2C_MOT                  0x4
  48 #define DP_AUX_NATIVE_WRITE             0x8
  49 #define DP_AUX_NATIVE_READ              0x9
  50
  51 #define DP_AUX_NATIVE_REPLY_ACK         (0x0 << 0)
  52 #define DP_AUX_NATIVE_REPLY_NACK        (0x1 << 0)
  53 #define DP_AUX_NATIVE_REPLY_DEFER       (0x2 << 0)
  54 #define DP_AUX_NATIVE_REPLY_MASK        (0x3 << 0)
  55
  56 #define DP_AUX_I2C_REPLY_ACK            (0x0 << 2)
  57 #define DP_AUX_I2C_REPLY_NACK           (0x1 << 2)
  58 #define DP_AUX_I2C_REPLY_DEFER          (0x2 << 2)
  59 #define DP_AUX_I2C_REPLY_MASK           (0x3 << 2)
  60
  61 /* AUX CH addresses */
  62 /* DPCD */
  63 #define DP_DPCD_REV                         0x000
  64
  65 #define DP_MAX_LINK_RATE                    0x001
  66
  67 #define DP_MAX_LANE_COUNT                   0x002
  68 # define DP_MAX_LANE_COUNT_MASK             0x1f
  69 # define DP_TPS3_SUPPORTED                  (1 << 6) /* 1.2 */
  70 # define DP_ENHANCED_FRAME_CAP              (1 << 7)
  71
  72 #define DP_MAX_DOWNSPREAD                   0x003
  73 # define DP_NO_AUX_HANDSHAKE_LINK_TRAINING  (1 << 6)
  74
  75 #define DP_NORP                             0x004
  76
  77 #define DP_DOWNSTREAMPORT_PRESENT           0x005
  78 # define DP_DWN_STRM_PORT_PRESENT           (1 << 0)
  79 # define DP_DWN_STRM_PORT_TYPE_MASK         0x06
  80 # define DP_DWN_STRM_PORT_TYPE_DP           (0 << 1)
  81 # define DP_DWN_STRM_PORT_TYPE_ANALOG       (1 << 1)
  82 # define DP_DWN_STRM_PORT_TYPE_TMDS         (2 << 1)
  83 # define DP_DWN_STRM_PORT_TYPE_OTHER        (3 << 1)
  84 # define DP_FORMAT_CONVERSION               (1 << 3)
  85 # define DP_DETAILED_CAP_INFO_AVAILABLE     (1 << 4) /* DPI */
  86
  87 #define DP_MAIN_LINK_CHANNEL_CODING         0x006
  88
  89 #define DP_DOWN_STREAM_PORT_COUNT           0x007
  90 # define DP_PORT_COUNT_MASK                 0x0f
  91 # define DP_MSA_TIMING_PAR_IGNORED          (1 << 6) /* eDP */
  92 # define DP_OUI_SUPPORT                     (1 << 7)
  93
  94 #define DP_I2C_SPEED_CAP                    0x00c    /* DPI */
  95 # define DP_I2C_SPEED_1K                    0x01
  96 # define DP_I2C_SPEED_5K                    0x02
  97 # define DP_I2C_SPEED_10K                   0x04
  98 # define DP_I2C_SPEED_100K                  0x08
  99 # define DP_I2C_SPEED_400K                  0x10
 100 # define DP_I2C_SPEED_1M                    0x20
 101
 102 #define DP_EDP_CONFIGURATION_CAP            0x00d   /* XXX 1.2? */
 103 #define DP_TRAINING_AUX_RD_INTERVAL         0x00e   /* XXX 1.2? */
 104
 105 /* Multiple stream transport */
 106 #define DP_MSTM_CAP                         0x021   /* 1.2 */
 107 # define DP_MST_CAP                         (1 << 0)
 108
 109 #define DP_PSR_SUPPORT                      0x070   /* XXX 1.2? */
 110 # define DP_PSR_IS_SUPPORTED                1
 111 #define DP_PSR_CAPS                         0x071   /* XXX 1.2? */
 112 # define DP_PSR_NO_TRAIN_ON_EXIT            1
 113 # define DP_PSR_SETUP_TIME_330              (0 << 1)
 114 # define DP_PSR_SETUP_TIME_275              (1 << 1)
 115 # define DP_PSR_SETUP_TIME_220              (2 << 1)
 116 # define DP_PSR_SETUP_TIME_165              (3 << 1)
 117 # define DP_PSR_SETUP_TIME_110              (4 << 1)
 118 # define DP_PSR_SETUP_TIME_55               (5 << 1)
 119 # define DP_PSR_SETUP_TIME_0                (6 << 1)
 120 # define DP_PSR_SETUP_TIME_MASK             (7 << 1)
 121 # define DP_PSR_SETUP_TIME_SHIFT            1
 122
 123 /*
 124  * 0x80-0x8f describe downstream port capabilities, but there are two layouts
 125  * based on whether DP_DETAILED_CAP_INFO_AVAILABLE was set.  If it was not,
 126  * each port's descriptor is one byte wide.  If it was set, each port's is
 127  * four bytes wide, starting with the one byte from the base info.  As of
 128  * DP interop v1.1a only VGA defines additional detail.
 129  */
 130
 131 /* offset 0 */
 132 #define DP_DOWNSTREAM_PORT_0                0x80
 133 # define DP_DS_PORT_TYPE_MASK               (7 << 0)
 134 # define DP_DS_PORT_TYPE_DP                 0
 135 # define DP_DS_PORT_TYPE_VGA                1
 136 # define DP_DS_PORT_TYPE_DVI                2
 137 # define DP_DS_PORT_TYPE_HDMI               3
 138 # define DP_DS_PORT_TYPE_NON_EDID           4
 139 # define DP_DS_PORT_HPD                     (1 << 3)
 140 /* offset 1 for VGA is maximum megapixels per second / 8 */
 141 /* offset 2 */
 142 # define DP_DS_VGA_MAX_BPC_MASK             (3 << 0)
 143 # define DP_DS_VGA_8BPC                     0
 144 # define DP_DS_VGA_10BPC                    1
 145 # define DP_DS_VGA_12BPC                    2
 146 # define DP_DS_VGA_16BPC                    3
 147
 148 /* link configuration */
 149 #define DP_LINK_BW_SET                      0x100
 150 # define DP_LINK_BW_1_62                    0x06
 151 # define DP_LINK_BW_2_7                     0x0a
 152 # define DP_LINK_BW_5_4                     0x14    /* 1.2 */
 153
 154 #define DP_LANE_COUNT_SET                   0x101
 155 # define DP_LANE_COUNT_MASK                 0x0f
 156 # define DP_LANE_COUNT_ENHANCED_FRAME_EN    (1 << 7)
 157
 158 #define DP_TRAINING_PATTERN_SET             0x102
 159 # define DP_TRAINING_PATTERN_DISABLE        0
 160 # define DP_TRAINING_PATTERN_1              1
 161 # define DP_TRAINING_PATTERN_2              2
 162 # define DP_TRAINING_PATTERN_3              3       /* 1.2 */
 163 # define DP_TRAINING_PATTERN_MASK           0x3
 164
 165 # define DP_LINK_QUAL_PATTERN_DISABLE       (0 << 2)
 166 # define DP_LINK_QUAL_PATTERN_D10_2         (1 << 2)
 167 # define DP_LINK_QUAL_PATTERN_ERROR_RATE    (2 << 2)
 168 # define DP_LINK_QUAL_PATTERN_PRBS7         (3 << 2)
 169 # define DP_LINK_QUAL_PATTERN_MASK          (3 << 2)
 170
 171 # define DP_RECOVERED_CLOCK_OUT_EN          (1 << 4)
 172 # define DP_LINK_SCRAMBLING_DISABLE         (1 << 5)
 173
 174 # define DP_SYMBOL_ERROR_COUNT_BOTH         (0 << 6)
 175 # define DP_SYMBOL_ERROR_COUNT_DISPARITY    (1 << 6)
 176 # define DP_SYMBOL_ERROR_COUNT_SYMBOL       (2 << 6)
 177 # define DP_SYMBOL_ERROR_COUNT_MASK         (3 << 6)
 178
 179 #define DP_TRAINING_LANE0_SET               0x103
 180 #define DP_TRAINING_LANE1_SET               0x104
 181 #define DP_TRAINING_LANE2_SET               0x105
 182 #define DP_TRAINING_LANE3_SET               0x106
 183
 184 # define DP_TRAIN_VOLTAGE_SWING_MASK        0x3
 185 # define DP_TRAIN_VOLTAGE_SWING_SHIFT       0
 186 # define DP_TRAIN_MAX_SWING_REACHED         (1 << 2)
 187 # define DP_TRAIN_VOLTAGE_SWING_400         (0 << 0)
 188 # define DP_TRAIN_VOLTAGE_SWING_600         (1 << 0)
 189 # define DP_TRAIN_VOLTAGE_SWING_800         (2 << 0)
 190 # define DP_TRAIN_VOLTAGE_SWING_1200        (3 << 0)
 191
 192 # define DP_TRAIN_PRE_EMPHASIS_MASK         (3 << 3)
 193 # define DP_TRAIN_PRE_EMPHASIS_0            (0 << 3)
 194 # define DP_TRAIN_PRE_EMPHASIS_3_5          (1 << 3)
 195 # define DP_TRAIN_PRE_EMPHASIS_6            (2 << 3)
 196 # define DP_TRAIN_PRE_EMPHASIS_9_5          (3 << 3)
 197
 198 # define DP_TRAIN_PRE_EMPHASIS_SHIFT        3
 199 # define DP_TRAIN_MAX_PRE_EMPHASIS_REACHED  (1 << 5)
 200
 201 #define DP_DOWNSPREAD_CTRL                  0x107
 202 # define DP_SPREAD_AMP_0_5                  (1 << 4)
 203 # define DP_MSA_TIMING_PAR_IGNORE_EN        (1 << 7) /* eDP */
 204
 205 #define DP_MAIN_LINK_CHANNEL_CODING_SET     0x108
 206 # define DP_SET_ANSI_8B10B                  (1 << 0)
 207
 208 #define DP_I2C_SPEED_CONTROL_STATUS         0x109   /* DPI */
 209 /* bitmask as for DP_I2C_SPEED_CAP */
 210
 211 #define DP_EDP_CONFIGURATION_SET            0x10a   /* XXX 1.2? */
 212
 213 #define DP_MSTM_CTRL                        0x111   /* 1.2 */
 214 # define DP_MST_EN                          (1 << 0)
 215 # define DP_UP_REQ_EN                       (1 << 1)
 216 # define DP_UPSTREAM_IS_SRC                 (1 << 2)
 217
 218 #define DP_PSR_EN_CFG                       0x170   /* XXX 1.2? */
 219 # define DP_PSR_ENABLE                      (1 << 0)
 220 # define DP_PSR_MAIN_LINK_ACTIVE            (1 << 1)
 221 # define DP_PSR_CRC_VERIFICATION            (1 << 2)
 222 # define DP_PSR_FRAME_CAPTURE               (1 << 3)
 223
 224 #define DP_SINK_COUNT                       0x200
 225 /* prior to 1.2 bit 7 was reserved mbz */
 226 # define DP_GET_SINK_COUNT(x)               ((((x) & 0x80) >> 1) | ((x) & 0x3f))
 227 # define DP_SINK_CP_READY                   (1 << 6)
 228
 229 #define DP_DEVICE_SERVICE_IRQ_VECTOR        0x201
 230 # define DP_REMOTE_CONTROL_COMMAND_PENDING  (1 << 0)
 231 # define DP_AUTOMATED_TEST_REQUEST          (1 << 1)
 232 # define DP_CP_IRQ                          (1 << 2)
 233 # define DP_SINK_SPECIFIC_IRQ               (1 << 6)
 234
 235 #define DP_LANE0_1_STATUS                   0x202
 236 #define DP_LANE2_3_STATUS                   0x203
 237 # define DP_LANE_CR_DONE                    (1 << 0)
 238 # define DP_LANE_CHANNEL_EQ_DONE            (1 << 1)
 239 # define DP_LANE_SYMBOL_LOCKED              (1 << 2)
 240
 241 #define DP_CHANNEL_EQ_BITS (DP_LANE_CR_DONE |           \
 242                             DP_LANE_CHANNEL_EQ_DONE |   \
 243                             DP_LANE_SYMBOL_LOCKED)
 244
 245 #define DP_LANE_ALIGN_STATUS_UPDATED        0x204
 246
 247 #define DP_INTERLANE_ALIGN_DONE             (1 << 0)
 248 #define DP_DOWNSTREAM_PORT_STATUS_CHANGED   (1 << 6)
 249 #define DP_LINK_STATUS_UPDATED              (1 << 7)
 250
 251 #define DP_SINK_STATUS                      0x205
 252
 253 #define DP_RECEIVE_PORT_0_STATUS            (1 << 0)
 254 #define DP_RECEIVE_PORT_1_STATUS            (1 << 1)
 255
 256 #define DP_ADJUST_REQUEST_LANE0_1           0x206
 257 #define DP_ADJUST_REQUEST_LANE2_3           0x207
 258 # define DP_ADJUST_VOLTAGE_SWING_LANE0_MASK  0x03
 259 # define DP_ADJUST_VOLTAGE_SWING_LANE0_SHIFT 0
 260 # define DP_ADJUST_PRE_EMPHASIS_LANE0_MASK   0x0c
 261 # define DP_ADJUST_PRE_EMPHASIS_LANE0_SHIFT  2
 262 # define DP_ADJUST_VOLTAGE_SWING_LANE1_MASK  0x30
 263 # define DP_ADJUST_VOLTAGE_SWING_LANE1_SHIFT 4
 264 # define DP_ADJUST_PRE_EMPHASIS_LANE1_MASK   0xc0
 265 # define DP_ADJUST_PRE_EMPHASIS_LANE1_SHIFT  6
 266
 267 #define DP_TEST_REQUEST                     0x218
 268 # define DP_TEST_LINK_TRAINING              (1 << 0)
 269 # define DP_TEST_LINK_VIDEO_PATTERN         (1 << 1)
 270 # define DP_TEST_LINK_EDID_READ             (1 << 2)
 271 # define DP_TEST_LINK_PHY_TEST_PATTERN      (1 << 3) /* DPCD >= 1.1 */
 272 # define DP_TEST_LINK_FAUX_PATTERN          (1 << 4) /* DPCD >= 1.2 */
 273
 274 #define DP_TEST_LINK_RATE                   0x219
 275 # define DP_LINK_RATE_162                   (0x6)
 276 # define DP_LINK_RATE_27                    (0xa)
 277
 278 #define DP_TEST_LANE_COUNT                  0x220
 279
 280 #define DP_TEST_PATTERN                     0x221
 281
 282 #define DP_TEST_CRC_R_CR                    0x240
 283 #define DP_TEST_CRC_G_Y                     0x242
 284 #define DP_TEST_CRC_B_CB                    0x244
 285
 286 #define DP_TEST_SINK_MISC                   0x246
 287 #define DP_TEST_CRC_SUPPORTED               (1 << 5)
 288
 289 #define DP_TEST_RESPONSE                    0x260
 290 # define DP_TEST_ACK                        (1 << 0)
 291 # define DP_TEST_NAK                        (1 << 1)
 292 # define DP_TEST_EDID_CHECKSUM_WRITE        (1 << 2)
 293
 294 #define DP_TEST_SINK                        0x270
 295 #define DP_TEST_SINK_START          (1 << 0)
 296
 297 #define DP_SOURCE_OUI                       0x300
 298 #define DP_SINK_OUI                         0x400
 299 #define DP_BRANCH_OUI                       0x500
 300
 301 #define DP_SET_POWER                        0x600
 302 # define DP_SET_POWER_D0                    0x1
 303 # define DP_SET_POWER_D3                    0x2
 304 # define DP_SET_POWER_MASK                  0x3
 305
 306 #define DP_PSR_ERROR_STATUS                 0x2006  /* XXX 1.2? */
 307 # define DP_PSR_LINK_CRC_ERROR              (1 << 0)
 308 # define DP_PSR_RFB_STORAGE_ERROR           (1 << 1)
 309
 310 #define DP_PSR_ESI                          0x2007  /* XXX 1.2? */
 311 # define DP_PSR_CAPS_CHANGE                 (1 << 0)
 312
 313 #define DP_PSR_STATUS                       0x2008  /* XXX 1.2? */
 314 # define DP_PSR_SINK_INACTIVE               0
 315 # define DP_PSR_SINK_ACTIVE_SRC_SYNCED      1
 316 # define DP_PSR_SINK_ACTIVE_RFB             2
 317 # define DP_PSR_SINK_ACTIVE_SINK_SYNCED     3
 318 # define DP_PSR_SINK_ACTIVE_RESYNC          4
 319 # define DP_PSR_SINK_INTERNAL_ERROR         7
 320 # define DP_PSR_SINK_STATE_MASK             0x07
 321
 322 #define MODE_I2C_START  1
 323 #define MODE_I2C_WRITE  2
 324 #define MODE_I2C_READ   4
 325 #define MODE_I2C_STOP   8
 326
 327 /**
 328  * struct i2c_algo_dp_aux_data - driver interface structure for i2c over dp
 329  *                               aux algorithm
 330  * @running: set by the algo indicating whether an i2c is ongoing or whether
 331  *           the i2c bus is quiescent
 332  * @address: i2c target address for the currently ongoing transfer
 333  * @aux_ch: driver callback to transfer a single byte of the i2c payload
 334  */
 335 struct i2c_algo_dp_aux_data {
 336         bool running;
 337         u16 address;
 338         int (*aux_ch) (struct i2c_adapter *adapter,
 339                        int mode, uint8_t write_byte,
 340                        uint8_t *read_byte);
 341 };
 342
 343 int
 344 i2c_dp_aux_add_bus(struct i2c_adapter *adapter);
 345
 346
 347 #define DP_LINK_STATUS_SIZE        6
 348 bool drm_dp_channel_eq_ok(const u8 link_status[DP_LINK_STATUS_SIZE],
 349                           int lane_count);
 350 bool drm_dp_clock_recovery_ok(const u8 link_status[DP_LINK_STATUS_SIZE],
 351                               int lane_count);
 352 u8 drm_dp_get_adjust_request_voltage(const u8 link_status[DP_LINK_STATUS_SIZE],
 353                                      int lane);
 354 u8 drm_dp_get_adjust_request_pre_emphasis(const u8 link_status[DP_LINK_STATUS_SIZE],
 355                                           int lane);
 356
 357 #define DP_RECEIVER_CAP_SIZE            0xf
 358 #define EDP_PSR_RECEIVER_CAP_SIZE       2
 359
 360 void drm_dp_link_train_clock_recovery_delay(const u8 dpcd[DP_RECEIVER_CAP_SIZE]);
 361 void drm_dp_link_train_channel_eq_delay(const u8 dpcd[DP_RECEIVER_CAP_SIZE]);
 362
 363 u8 drm_dp_link_rate_to_bw_code(int link_rate);
 364 int drm_dp_bw_code_to_link_rate(u8 link_bw);
 365
 366 struct edp_sdp_header {
 367         u8 HB0; /* Secondary Data Packet ID */
 368         u8 HB1; /* Secondary Data Packet Type */
 369         u8 HB2; /* 7:5 reserved, 4:0 revision number */
 370         u8 HB3; /* 7:5 reserved, 4:0 number of valid data bytes */
 371 } __packed;
 372
 373 #define EDP_SDP_HEADER_REVISION_MASK            0x1F
 374 #define EDP_SDP_HEADER_VALID_PAYLOAD_BYTES      0x1F
 375
 376 struct edp_vsc_psr {
 377         struct edp_sdp_header sdp_header;
 378         u8 DB0; /* Stereo Interface */
 379         u8 DB1; /* 0 - PSR State; 1 - Update RFB; 2 - CRC Valid */
 380         u8 DB2; /* CRC value bits 7:0 of the R or Cr component */
 381         u8 DB3; /* CRC value bits 15:8 of the R or Cr component */
 382         u8 DB4; /* CRC value bits 7:0 of the G or Y component */
 383         u8 DB5; /* CRC value bits 15:8 of the G or Y component */
 384         u8 DB6; /* CRC value bits 7:0 of the B or Cb component */
 385         u8 DB7; /* CRC value bits 15:8 of the B or Cb component */
 386         u8 DB8_31[24]; /* Reserved */
 387 } __packed;
 388
 389 #define EDP_VSC_PSR_STATE_ACTIVE        (1<<0)
 390 #define EDP_VSC_PSR_UPDATE_RFB          (1<<1)
 391 #define EDP_VSC_PSR_CRC_VALUES_VALID    (1<<2)
 392
 393 static inline int
 394 drm_dp_max_link_rate(const u8 dpcd[DP_RECEIVER_CAP_SIZE])
 395 {
 396         return drm_dp_bw_code_to_link_rate(dpcd[DP_MAX_LINK_RATE]);
 397 }
 398
 399 static inline u8
 400 drm_dp_max_lane_count(const u8 dpcd[DP_RECEIVER_CAP_SIZE])
 401 {
 402         return dpcd[DP_MAX_LANE_COUNT] & DP_MAX_LANE_COUNT_MASK;
 403 }
 404
 405 static inline bool
 406 drm_dp_enhanced_frame_cap(const u8 dpcd[DP_RECEIVER_CAP_SIZE])
 407 {
 408         return dpcd[DP_DPCD_REV] >= 0x11 &&
 409                 (dpcd[DP_MAX_LANE_COUNT] & DP_ENHANCED_FRAME_CAP);
 410 }
 411
 412 /*
 413  * DisplayPort AUX channel
 414  */
 415
 416 /**
 417  * struct drm_dp_aux_msg - DisplayPort AUX channel transaction
 418  * @address: address of the (first) register to access
 419  * @request: contains the type of transaction (see DP_AUX_* macros)
 420  * @reply: upon completion, contains the reply type of the transaction
 421  * @buffer: pointer to a transmission or reception buffer
 422  * @size: size of @buffer
 423  */
 424 struct drm_dp_aux_msg {
 425         unsigned int address;
 426         u8 request;
 427         u8 reply;
 428         void *buffer;
 429         size_t size;
 430 };
 431
 432 /**
 433  * struct drm_dp_aux - DisplayPort AUX channel
 434  * @ddc: I2C adapter that can be used for I2C-over-AUX communication
 435  * @dev: pointer to struct device that is the parent for this AUX channel
 436  * @transfer: transfers a message representing a single AUX transaction
 437  *
 438  * The .dev field should be set to a pointer to the device that implements
 439  * the AUX channel.
 440  *
 441  * The .name field may be used to specify the name of the I2C adapter. If set to
 442  * NULL, dev_name() of .dev will be used.
 443  *
 444  * Drivers provide a hardware-specific implementation of how transactions
 445  * are executed via the .transfer() function. A pointer to a drm_dp_aux_msg
 446  * structure describing the transaction is passed into this function. Upon
 447  * success, the implementation should return the number of payload bytes
 448  * that were transferred, or a negative error-code on failure. Helpers
 449  * propagate errors from the .transfer() function, with the exception of
 450  * the -EBUSY error, which causes a transaction to be retried. On a short,
 451  * helpers will return -EPROTO to make it simpler to check for failure.
 452  *
 453  * An AUX channel can also be used to transport I2C messages to a sink. A
 454  * typical application of that is to access an EDID that's present in the
 455  * sink device. The .transfer() function can also be used to execute such
 456  * transactions. The drm_dp_aux_register_i2c_bus() function registers an
 457  * I2C adapter that can be passed to drm_probe_ddc(). Upon removal, drivers
 458  * should call drm_dp_aux_unregister_i2c_bus() to remove the I2C adapter.
 459  */
 460 struct drm_dp_aux {
 461         const char *name;
 462         struct i2c_adapter ddc;
 463         struct device *dev;
 464
 465         ssize_t (*transfer)(struct drm_dp_aux *aux,
 466                             struct drm_dp_aux_msg *msg);
 467 };
 468
 469 ssize_t drm_dp_dpcd_read(struct drm_dp_aux *aux, unsigned int offset,
 470                          void *buffer, size_t size);
 471 ssize_t drm_dp_dpcd_write(struct drm_dp_aux *aux, unsigned int offset,
 472                           void *buffer, size_t size);
 473
 474 /**
 475  * drm_dp_dpcd_readb() - read a single byte from the DPCD
 476  * @aux: DisplayPort AUX channel
 477  * @offset: address of the register to read
 478  * @valuep: location where the value of the register will be stored
 479  *
 480  * Returns the number of bytes transferred (1) on success, or a negative
 481  * error code on failure.
 482  */
 483 static inline ssize_t drm_dp_dpcd_readb(struct drm_dp_aux *aux,
 484                                         unsigned int offset, u8 *valuep)
 485 {
 486         return drm_dp_dpcd_read(aux, offset, valuep, 1);
 487 }
 488
 489 /**
 490  * drm_dp_dpcd_writeb() - write a single byte to the DPCD
 491  * @aux: DisplayPort AUX channel
 492  * @offset: address of the register to write
 493  * @value: value to write to the register
 494  *
 495  * Returns the number of bytes transferred (1) on success, or a negative
 496  * error code on failure.
 497  */
 498 static inline ssize_t drm_dp_dpcd_writeb(struct drm_dp_aux *aux,
 499                                          unsigned int offset, u8 value)
 500 {
 501         return drm_dp_dpcd_write(aux, offset, &value, 1);
 502 }
 503
 504 int drm_dp_dpcd_read_link_status(struct drm_dp_aux *aux,
 505                                  u8 status[DP_LINK_STATUS_SIZE]);
 506
 507 /*
 508  * DisplayPort link
 509  */
 510 #define DP_LINK_CAP_ENHANCED_FRAMING (1 << 0)
 511
 512 struct drm_dp_link {
 513         unsigned char revision;
 514         unsigned int rate;
 515         unsigned int num_lanes;
 516         unsigned long capabilities;
 517 };
 518
 519 int drm_dp_link_probe(struct drm_dp_aux *aux, struct drm_dp_link *link);
 520 int drm_dp_link_power_up(struct drm_dp_aux *aux, struct drm_dp_link *link);
 521 int drm_dp_link_configure(struct drm_dp_aux *aux, struct drm_dp_link *link);
 522
 523 int drm_dp_aux_register_i2c_bus(struct drm_dp_aux *aux);
 524 void drm_dp_aux_unregister_i2c_bus(struct drm_dp_aux *aux);
 525
 526 #endif /* _DRM_DP_HELPER_H_ */