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  1. /*
  2.  * Copyright © 2009 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. #include <linux/kernel.h>
  24. #include <linux/module.h>
  25. //#include <linux/delay.h>
  26. //#include <linux/init.h>
  27. #include <linux/errno.h>
  28. #include <linux/sched.h>
  29. #include <linux/i2c.h>
  30. #include "drm_dp_helper.h"
  31. #include "drmP.h"
  32.  
  33. /* Run a single AUX_CH I2C transaction, writing/reading data as necessary */
  34. static int
  35. i2c_algo_dp_aux_transaction(struct i2c_adapter *adapter, int mode,
  36.                             uint8_t write_byte, uint8_t *read_byte)
  37. {
  38.         struct i2c_algo_dp_aux_data *algo_data = adapter->algo_data;
  39.         int ret;
  40.  
  41.         ret = (*algo_data->aux_ch)(adapter, mode,
  42.                                    write_byte, read_byte);
  43.         return ret;
  44. }
  45.  
  46. /*
  47.  * I2C over AUX CH
  48.  */
  49.  
  50. /*
  51.  * Send the address. If the I2C link is running, this 'restarts'
  52.  * the connection with the new address, this is used for doing
  53.  * a write followed by a read (as needed for DDC)
  54.  */
  55. static int
  56. i2c_algo_dp_aux_address(struct i2c_adapter *adapter, u16 address, bool reading)
  57. {
  58.         struct i2c_algo_dp_aux_data *algo_data = adapter->algo_data;
  59.         int mode = MODE_I2C_START;
  60.         int ret;
  61.  
  62.         if (reading)
  63.                 mode |= MODE_I2C_READ;
  64.         else
  65.                 mode |= MODE_I2C_WRITE;
  66.         algo_data->address = address;
  67.         algo_data->running = true;
  68.         ret = i2c_algo_dp_aux_transaction(adapter, mode, 0, NULL);
  69.         return ret;
  70. }
  71.  
  72. /*
  73.  * Stop the I2C transaction. This closes out the link, sending
  74.  * a bare address packet with the MOT bit turned off
  75.  */
  76. static void
  77. i2c_algo_dp_aux_stop(struct i2c_adapter *adapter, bool reading)
  78. {
  79.         struct i2c_algo_dp_aux_data *algo_data = adapter->algo_data;
  80.         int mode = MODE_I2C_STOP;
  81.  
  82.         if (reading)
  83.                 mode |= MODE_I2C_READ;
  84.         else
  85.                 mode |= MODE_I2C_WRITE;
  86.         if (algo_data->running) {
  87.                 (void) i2c_algo_dp_aux_transaction(adapter, mode, 0, NULL);
  88.                 algo_data->running = false;
  89.         }
  90. }
  91.  
  92. /*
  93.  * Write a single byte to the current I2C address, the
  94.  * the I2C link must be running or this returns -EIO
  95.  */
  96. static int
  97. i2c_algo_dp_aux_put_byte(struct i2c_adapter *adapter, u8 byte)
  98. {
  99.         struct i2c_algo_dp_aux_data *algo_data = adapter->algo_data;
  100.         int ret;
  101.  
  102.         if (!algo_data->running)
  103.                 return -EIO;
  104.  
  105.         ret = i2c_algo_dp_aux_transaction(adapter, MODE_I2C_WRITE, byte, NULL);
  106.         return ret;
  107. }
  108.  
  109. /*
  110.  * Read a single byte from the current I2C address, the
  111.  * I2C link must be running or this returns -EIO
  112.  */
  113. static int
  114. i2c_algo_dp_aux_get_byte(struct i2c_adapter *adapter, u8 *byte_ret)
  115. {
  116.         struct i2c_algo_dp_aux_data *algo_data = adapter->algo_data;
  117.         int ret;
  118.  
  119.         if (!algo_data->running)
  120.                 return -EIO;
  121.  
  122.         ret = i2c_algo_dp_aux_transaction(adapter, MODE_I2C_READ, 0, byte_ret);
  123.         return ret;
  124. }
  125.  
  126. static int
  127. i2c_algo_dp_aux_xfer(struct i2c_adapter *adapter,
  128.                      struct i2c_msg *msgs,
  129.                      int num)
  130. {
  131.         int ret = 0;
  132.         bool reading = false;
  133.         int m;
  134.         int b;
  135.  
  136.         for (m = 0; m < num; m++) {
  137.                 u16 len = msgs[m].len;
  138.                 u8 *buf = msgs[m].buf;
  139.                 reading = (msgs[m].flags & I2C_M_RD) != 0;
  140.                 ret = i2c_algo_dp_aux_address(adapter, msgs[m].addr, reading);
  141.                 if (ret < 0)
  142.                         break;
  143.                 if (reading) {
  144.                         for (b = 0; b < len; b++) {
  145.                                 ret = i2c_algo_dp_aux_get_byte(adapter, &buf[b]);
  146.                                 if (ret < 0)
  147.                                         break;
  148.                         }
  149.                 } else {
  150.                         for (b = 0; b < len; b++) {
  151.                                 ret = i2c_algo_dp_aux_put_byte(adapter, buf[b]);
  152.                                 if (ret < 0)
  153.                                         break;
  154.                         }
  155.                 }
  156.                 if (ret < 0)
  157.                         break;
  158.         }
  159.         if (ret >= 0)
  160.                 ret = num;
  161.         i2c_algo_dp_aux_stop(adapter, reading);
  162.         DRM_DEBUG_KMS("dp_aux_xfer return %d\n", ret);
  163.         return ret;
  164. }
  165.  
  166. static u32
  167. i2c_algo_dp_aux_functionality(struct i2c_adapter *adapter)
  168. {
  169.         return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL |
  170.                I2C_FUNC_SMBUS_READ_BLOCK_DATA |
  171.                I2C_FUNC_SMBUS_BLOCK_PROC_CALL |
  172.                I2C_FUNC_10BIT_ADDR;
  173. }
  174.  
  175. static const struct i2c_algorithm i2c_dp_aux_algo = {
  176.         .master_xfer    = i2c_algo_dp_aux_xfer,
  177.         .functionality  = i2c_algo_dp_aux_functionality,
  178. };
  179.  
  180. static void
  181. i2c_dp_aux_reset_bus(struct i2c_adapter *adapter)
  182. {
  183.         (void) i2c_algo_dp_aux_address(adapter, 0, false);
  184.         (void) i2c_algo_dp_aux_stop(adapter, false);
  185.  
  186. }
  187.  
  188. static int
  189. i2c_dp_aux_prepare_bus(struct i2c_adapter *adapter)
  190. {
  191.         adapter->algo = &i2c_dp_aux_algo;
  192.         adapter->retries = 3;
  193.         i2c_dp_aux_reset_bus(adapter);
  194.         return 0;
  195. }
  196.  
  197. int
  198. i2c_dp_aux_add_bus(struct i2c_adapter *adapter)
  199. {
  200.         int error;
  201.  
  202.         error = i2c_dp_aux_prepare_bus(adapter);
  203.         if (error)
  204.                 return error;
  205. //   error = i2c_add_adapter(adapter);
  206.         return error;
  207. }
  208. EXPORT_SYMBOL(i2c_dp_aux_add_bus);
  209.