drivers/video/s6e63d6.c

   1 /*
   2  * Copyright (C) 2009
   3  * Guennadi Liakhovetski, DENX Software Engineering, <lg@denx.de>
   4  *
   5  * SPDX-License-Identifier:     GPL-2.0+
   6  */
   7 #include <common.h>
   8 #include <spi.h>
   9 #include <s6e63d6.h>
  10
  11 /*
  12  * Each transfer is performed as:
  13  * 1. chip-select active
  14  * 2. send 8-bit start code
  15  * 3. send 16-bit data
  16  * 4. chip-select inactive
  17  */
  18 static int send_word(struct s6e63d6 *data, u8 rs, u16 word)
  19 {
  20         /*
  21          * The start byte looks like (binary):
  22          * 01110<ID><RS><R/W>
  23          * RS is 0 for index or 1 for data, and R/W is 0 for write.
  24          */
  25         u32 buf8 = 0x70 | data->id | (rs & 2);
  26         u32 buf16 = cpu_to_le16(word);
  27         u32 buf_in;
  28         int err;
  29
  30         err = spi_xfer(data->slave, 8, &buf8, &buf_in, SPI_XFER_BEGIN);
  31         if (err)
  32                 return err;
  33
  34         return spi_xfer(data->slave, 16, &buf16, &buf_in, SPI_XFER_END);
  35 }
  36
  37 /* Index and param differ in Register Select bit */
  38 int s6e63d6_index(struct s6e63d6 *data, u8 idx)
  39 {
  40         return send_word(data, 0, idx);
  41 }
  42
  43 int s6e63d6_param(struct s6e63d6 *data, u16 param)
  44 {
  45         return send_word(data, 2, param);
  46 }
  47
  48 int s6e63d6_init(struct s6e63d6 *data)
  49 {
  50         if (data->id != 0 && data->id != 4) {
  51                 printf("s6e63d6: invalid ID %u\n", data->id);
  52                 return 1;
  53         }
  54
  55         data->slave = spi_setup_slave(data->bus, data->cs, 100000, SPI_MODE_3);
  56         if (!data->slave)
  57                 return 1;
  58
  59         return 0;
  60 }