drivers/gpu/drm/drm_dp_dual_mode_helper.c

   1 /*
   2  * Copyright © 2016 Intel Corporation
   3  *
   4  * Permission is hereby granted, free of charge, to any person obtaining a
   5  * copy of this software and associated documentation files (the "Software"),
   6  * to deal in the Software without restriction, including without limitation
   7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   8  * and/or sell copies of the Software, and to permit persons to whom the
   9  * Software is furnished to do so, subject to the following conditions:
  10  *
  11  * The above copyright notice and this permission notice shall be included in
  12  * all copies or substantial portions of the Software.
  13  *
  14  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  15  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  17  * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
  18  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
  19  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  20  * OTHER DEALINGS IN THE SOFTWARE.
  21  */
  22
  23 #include <linux/errno.h>
  24 #include <linux/export.h>
  25 #include <linux/i2c.h>
  26 #include <linux/slab.h>
  27 #include <linux/string.h>
  28 #include <drm/drm_dp_dual_mode_helper.h>
  29 #include <drm/drmP.h>
  30
  31 /**
  32  * DOC: dp dual mode helpers
  33  *
  34  * Helper functions to deal with DP dual mode (aka. DP++) adaptors.
  35  *
  36  * Type 1:
  37  * Adaptor registers (if any) and the sink DDC bus may be accessed via I2C.
  38  *
  39  * Type 2:
  40  * Adaptor registers and sink DDC bus can be accessed either via I2C or
  41  * I2C-over-AUX. Source devices may choose to implement either of these
  42  * access methods.
  43  */
  44
  45 #define DP_DUAL_MODE_SLAVE_ADDRESS 0x40
  46
  47 /**
  48  * drm_dp_dual_mode_read - Read from the DP dual mode adaptor register(s)
  49  * @adapter: I2C adapter for the DDC bus
  50  * @offset: register offset
  51  * @buffer: buffer for return data
  52  * @size: sizo of the buffer
  53  *
  54  * Reads @size bytes from the DP dual mode adaptor registers
  55  * starting at @offset.
  56  *
  57  * Returns:
  58  * 0 on success, negative error code on failure
  59  */
  60 ssize_t drm_dp_dual_mode_read(struct i2c_adapter *adapter,
  61                               u8 offset, void *buffer, size_t size)
  62 {
  63         struct i2c_msg msgs[] = {
  64                 {
  65                         .addr = DP_DUAL_MODE_SLAVE_ADDRESS,
  66                         .flags = 0,
  67                         .len = 1,
  68                         .buf = &offset,
  69                 },
  70                 {
  71                         .addr = DP_DUAL_MODE_SLAVE_ADDRESS,
  72                         .flags = I2C_M_RD,
  73                         .len = size,
  74                         .buf = buffer,
  75                 },
  76         };
  77         int ret;
  78
  79         ret = i2c_transfer(adapter, msgs, ARRAY_SIZE(msgs));
  80         if (ret < 0)
  81                 return ret;
  82         if (ret != ARRAY_SIZE(msgs))
  83                 return -EPROTO;
  84
  85         return 0;
  86 }
  87 EXPORT_SYMBOL(drm_dp_dual_mode_read);
  88
  89 /**
  90  * drm_dp_dual_mode_write - Write to the DP dual mode adaptor register(s)
  91  * @adapter: I2C adapter for the DDC bus
  92  * @offset: register offset
  93  * @buffer: buffer for write data
  94  * @size: sizo of the buffer
  95  *
  96  * Writes @size bytes to the DP dual mode adaptor registers
  97  * starting at @offset.
  98  *
  99  * Returns:
 100  * 0 on success, negative error code on failure
 101  */
 102 ssize_t drm_dp_dual_mode_write(struct i2c_adapter *adapter,
 103                                u8 offset, const void *buffer, size_t size)
 104 {
 105         struct i2c_msg msg = {
 106                 .addr = DP_DUAL_MODE_SLAVE_ADDRESS,
 107                 .flags = 0,
 108                 .len = 1 + size,
 109                 .buf = NULL,
 110         };
 111         void *data;
 112         int ret;
 113
 114         data = kmalloc(msg.len, GFP_TEMPORARY);
 115         if (!data)
 116                 return -ENOMEM;
 117
 118         msg.buf = data;
 119
 120         memcpy(data, &offset, 1);
 121         memcpy(data + 1, buffer, size);
 122
 123         ret = i2c_transfer(adapter, &msg, 1);
 124
 125         kfree(data);
 126
 127         if (ret < 0)
 128                 return ret;
 129         if (ret != 1)
 130                 return -EPROTO;
 131
 132         return 0;
 133 }
 134 EXPORT_SYMBOL(drm_dp_dual_mode_write);
 135
 136 static bool is_hdmi_adaptor(const char hdmi_id[DP_DUAL_MODE_HDMI_ID_LEN])
 137 {
 138         static const char dp_dual_mode_hdmi_id[DP_DUAL_MODE_HDMI_ID_LEN] =
 139                 "DP-HDMI ADAPTOR\x04";
 140
 141         return memcmp(hdmi_id, dp_dual_mode_hdmi_id,
 142                       sizeof(dp_dual_mode_hdmi_id)) == 0;
 143 }
 144
 145 static bool is_type2_adaptor(uint8_t adaptor_id)
 146 {
 147         return adaptor_id == (DP_DUAL_MODE_TYPE_TYPE2 |
 148                               DP_DUAL_MODE_REV_TYPE2);
 149 }
 150
 151 /**
 152  * drm_dp_dual_mode_detect - Identify the DP dual mode adaptor
 153  * @adapter: I2C adapter for the DDC bus
 154  *
 155  * Attempt to identify the type of the DP dual mode adaptor used.
 156  *
 157  * Note that when the answer is @DRM_DP_DUAL_MODE_UNKNOWN it's not
 158  * certain whether we're dealing with a native HDMI port or
 159  * a type 1 DVI dual mode adaptor. The driver will have to use
 160  * some other hardware/driver specific mechanism to make that
 161  * distinction.
 162  *
 163  * Returns:
 164  * The type of the DP dual mode adaptor used
 165  */
 166 enum drm_dp_dual_mode_type drm_dp_dual_mode_detect(struct i2c_adapter *adapter)
 167 {
 168         char hdmi_id[DP_DUAL_MODE_HDMI_ID_LEN] = {};
 169         uint8_t adaptor_id = 0x00;
 170         ssize_t ret;
 171
 172         /*
 173          * Let's see if the adaptor is there the by reading the
 174          * HDMI ID registers.
 175          *
 176          * Note that type 1 DVI adaptors are not required to implemnt
 177          * any registers, and that presents a problem for detection.
 178          * If the i2c transfer is nacked, we may or may not be dealing
 179          * with a type 1 DVI adaptor. Some other mechanism of detecting
 180          * the presence of the adaptor is required. One way would be
 181          * to check the state of the CONFIG1 pin, Another method would
 182          * simply require the driver to know whether the port is a DP++
 183          * port or a native HDMI port. Both of these methods are entirely
 184          * hardware/driver specific so we can't deal with them here.
 185          */
 186         ret = drm_dp_dual_mode_read(adapter, DP_DUAL_MODE_HDMI_ID,
 187                                     hdmi_id, sizeof(hdmi_id));
 188         if (ret)
 189                 return DRM_DP_DUAL_MODE_UNKNOWN;
 190
 191         /*
 192          * Sigh. Some (maybe all?) type 1 adaptors are broken and ack
 193          * the offset but ignore it, and instead they just always return
 194          * data from the start of the HDMI ID buffer. So for a broken
 195          * type 1 HDMI adaptor a single byte read will always give us
 196          * 0x44, and for a type 1 DVI adaptor it should give 0x00
 197          * (assuming it implements any registers). Fortunately neither
 198          * of those values will match the type 2 signature of the
 199          * DP_DUAL_MODE_ADAPTOR_ID register so we can proceed with
 200          * the type 2 adaptor detection safely even in the presence
 201          * of broken type 1 adaptors.
 202          */
 203         ret = drm_dp_dual_mode_read(adapter, DP_DUAL_MODE_ADAPTOR_ID,
 204                                     &adaptor_id, sizeof(adaptor_id));
 205         if (ret == 0) {
 206                 if (is_type2_adaptor(adaptor_id)) {
 207                         if (is_hdmi_adaptor(hdmi_id))
 208                                 return DRM_DP_DUAL_MODE_TYPE2_HDMI;
 209                         else
 210                                 return DRM_DP_DUAL_MODE_TYPE2_DVI;
 211                 }
 212         }
 213
 214         if (is_hdmi_adaptor(hdmi_id))
 215                 return DRM_DP_DUAL_MODE_TYPE1_HDMI;
 216         else
 217                 return DRM_DP_DUAL_MODE_TYPE1_DVI;
 218 }
 219 EXPORT_SYMBOL(drm_dp_dual_mode_detect);
 220
 221 /**
 222  * drm_dp_dual_mode_max_tmds_clock - Max TMDS clock for DP dual mode adaptor
 223  * @type: DP dual mode adaptor type
 224  * @adapter: I2C adapter for the DDC bus
 225  *
 226  * Determine the max TMDS clock the adaptor supports based on the
 227  * type of the dual mode adaptor and the DP_DUAL_MODE_MAX_TMDS_CLOCK
 228  * register (on type2 adaptors). As some type 1 adaptors have
 229  * problems with registers (see comments in drm_dp_dual_mode_detect())
 230  * we don't read the register on those, instead we simply assume
 231  * a 165 MHz limit based on the specification.
 232  *
 233  * Returns:
 234  * Maximum supported TMDS clock rate for the DP dual mode adaptor in kHz.
 235  */
 236 int drm_dp_dual_mode_max_tmds_clock(enum drm_dp_dual_mode_type type,
 237                                     struct i2c_adapter *adapter)
 238 {
 239         uint8_t max_tmds_clock;
 240         ssize_t ret;
 241
 242         /* native HDMI so no limit */
 243         if (type == DRM_DP_DUAL_MODE_NONE)
 244                 return 0;
 245
 246         /*
 247          * Type 1 adaptors are limited to 165MHz
 248          * Type 2 adaptors can tells us their limit
 249          */
 250         if (type < DRM_DP_DUAL_MODE_TYPE2_DVI)
 251                 return 165000;
 252
 253         ret = drm_dp_dual_mode_read(adapter, DP_DUAL_MODE_MAX_TMDS_CLOCK,
 254                                     &max_tmds_clock, sizeof(max_tmds_clock));
 255         if (ret || max_tmds_clock == 0x00 || max_tmds_clock == 0xff) {
 256                 DRM_DEBUG_KMS("Failed to query max TMDS clock\n");
 257                 return 165000;
 258         }
 259
 260         return max_tmds_clock * 5000 / 2;
 261 }
 262 EXPORT_SYMBOL(drm_dp_dual_mode_max_tmds_clock);
 263
 264 /**
 265  * drm_dp_dual_mode_get_tmds_output - Get the state of the TMDS output buffers in the DP dual mode adaptor
 266  * @type: DP dual mode adaptor type
 267  * @adapter: I2C adapter for the DDC bus
 268  * @enabled: current state of the TMDS output buffers
 269  *
 270  * Get the state of the TMDS output buffers in the adaptor. For
 271  * type2 adaptors this is queried from the DP_DUAL_MODE_TMDS_OEN
 272  * register. As some type 1 adaptors have problems with registers
 273  * (see comments in drm_dp_dual_mode_detect()) we don't read the
 274  * register on those, instead we simply assume that the buffers
 275  * are always enabled.
 276  *
 277  * Returns:
 278  * 0 on success, negative error code on failure
 279  */
 280 int drm_dp_dual_mode_get_tmds_output(enum drm_dp_dual_mode_type type,
 281                                      struct i2c_adapter *adapter,
 282                                      bool *enabled)
 283 {
 284         uint8_t tmds_oen;
 285         ssize_t ret;
 286
 287         if (type < DRM_DP_DUAL_MODE_TYPE2_DVI) {
 288                 *enabled = true;
 289                 return 0;
 290         }
 291
 292         ret = drm_dp_dual_mode_read(adapter, DP_DUAL_MODE_TMDS_OEN,
 293                                     &tmds_oen, sizeof(tmds_oen));
 294         if (ret) {
 295                 DRM_DEBUG_KMS("Failed to query state of TMDS output buffers\n");
 296                 return ret;
 297         }
 298
 299         *enabled = !(tmds_oen & DP_DUAL_MODE_TMDS_DISABLE);
 300
 301         return 0;
 302 }
 303 EXPORT_SYMBOL(drm_dp_dual_mode_get_tmds_output);
 304
 305 /**
 306  * drm_dp_dual_mode_set_tmds_output - Enable/disable TMDS output buffers in the DP dual mode adaptor
 307  * @type: DP dual mode adaptor type
 308  * @adapter: I2C adapter for the DDC bus
 309  * @enable: enable (as opposed to disable) the TMDS output buffers
 310  *
 311  * Set the state of the TMDS output buffers in the adaptor. For
 312  * type2 this is set via the DP_DUAL_MODE_TMDS_OEN register. As
 313  * some type 1 adaptors have problems with registers (see comments
 314  * in drm_dp_dual_mode_detect()) we avoid touching the register,
 315  * making this function a no-op on type 1 adaptors.
 316  *
 317  * Returns:
 318  * 0 on success, negative error code on failure
 319  */
 320 int drm_dp_dual_mode_set_tmds_output(enum drm_dp_dual_mode_type type,
 321                                      struct i2c_adapter *adapter, bool enable)
 322 {
 323         uint8_t tmds_oen = enable ? 0 : DP_DUAL_MODE_TMDS_DISABLE;
 324         ssize_t ret;
 325
 326         if (type < DRM_DP_DUAL_MODE_TYPE2_DVI)
 327                 return 0;
 328
 329         ret = drm_dp_dual_mode_write(adapter, DP_DUAL_MODE_TMDS_OEN,
 330                                      &tmds_oen, sizeof(tmds_oen));
 331         if (ret) {
 332                 DRM_DEBUG_KMS("Failed to %s TMDS output buffers\n",
 333                               enable ? "enable" : "disable");
 334                 return ret;
 335         }
 336
 337         return 0;
 338 }
 339 EXPORT_SYMBOL(drm_dp_dual_mode_set_tmds_output);
 340
 341 /**
 342  * drm_dp_get_dual_mode_type_name - Get the name of the DP dual mode adaptor type as a string
 343  * @type: DP dual mode adaptor type
 344  *
 345  * Returns:
 346  * String representation of the DP dual mode adaptor type
 347  */
 348 const char *drm_dp_get_dual_mode_type_name(enum drm_dp_dual_mode_type type)
 349 {
 350         switch (type) {
 351         case DRM_DP_DUAL_MODE_NONE:
 352                 return "none";
 353         case DRM_DP_DUAL_MODE_TYPE1_DVI:
 354                 return "type 1 DVI";
 355         case DRM_DP_DUAL_MODE_TYPE1_HDMI:
 356                 return "type 1 HDMI";
 357         case DRM_DP_DUAL_MODE_TYPE2_DVI:
 358                 return "type 2 DVI";
 359         case DRM_DP_DUAL_MODE_TYPE2_HDMI:
 360                 return "type 2 HDMI";
 361         default:
 362                 WARN_ON(type != DRM_DP_DUAL_MODE_UNKNOWN);
 363                 return "unknown";
 364         }
 365 }
 366 EXPORT_SYMBOL(drm_dp_get_dual_mode_type_name);