src/drivers/aspeed/common/ast_i2c.c

   1 /* SPDX-License-Identifier: MIT */
   2 /*
   3  * Copied from Linux drivers/gpu/drm/ast/ast_mode.c
   4  */
   5 #include <delay.h>
   6 #include <device/i2c_simple.h>
   7
   8 #include "ast_drv.h"
   9
  10 static struct ast_private *ast;
  11
  12 #define _GET_INDEX_REG(x) ast_get_index_reg_mask(ast, AST_IO_CRTC_PORT, 0xb7, (x))
  13 #define ASPEED_BUS 0
  14
  15 static int get_clock(unsigned int bus)
  16 {
  17         uint32_t val, val2, count, pass;
  18
  19         count = 0;
  20         pass = 0;
  21         val = (_GET_INDEX_REG(0x10) >> 4) & 0x01;
  22         do {
  23                 val2 = (_GET_INDEX_REG(0x10) >> 4) & 0x01;
  24                 if (val == val2) {
  25                         pass++;
  26                 } else {
  27                         pass = 0;
  28                         val = (_GET_INDEX_REG(0x10) >> 4) & 0x01;
  29                 }
  30         } while ((pass < 5) && (count++ < 0x10000));
  31
  32         return val & 1 ? 1 : 0;
  33 }
  34
  35 static int get_data(unsigned int bus)
  36 {
  37         uint32_t val, val2, count, pass;
  38
  39         count = 0;
  40         pass = 0;
  41         val = (_GET_INDEX_REG(0x20) >> 5) & 0x01;
  42         do {
  43                 val2 = (_GET_INDEX_REG(0x20) >> 5) & 0x01;
  44                 if (val == val2) {
  45                         pass++;
  46                 } else {
  47                         pass = 0;
  48                         val = (_GET_INDEX_REG(0x20) >> 5) & 0x01;
  49                 }
  50         } while ((pass < 5) && (count++ < 0x10000));
  51
  52         return val & 1 ? 1 : 0;
  53 }
  54
  55 static void set_clock(unsigned int bus, int clock)
  56 {
  57         int i;
  58         u8 ujcrb7, jtemp;
  59
  60         for (i = 0; i < 0x10000; i++) {
  61                 ujcrb7 = ((clock & 0x01) ? 0 : 1);
  62                 ast_set_index_reg_mask(ast, AST_IO_CRTC_PORT, 0xb7, 0xf4, ujcrb7);
  63                 jtemp = ast_get_index_reg_mask(ast, AST_IO_CRTC_PORT, 0xb7, 0x01);
  64                 if (ujcrb7 == jtemp)
  65                         break;
  66         }
  67 }
  68
  69 static void set_data(unsigned int bus, int data)
  70 {
  71         int i;
  72         u8 ujcrb7, jtemp;
  73
  74         for (i = 0; i < 0x10000; i++) {
  75                 ujcrb7 = ((data & 0x01) ? 0 : 1) << 2;
  76                 ast_set_index_reg_mask(ast, AST_IO_CRTC_PORT, 0xb7, 0xf1, ujcrb7);
  77                 jtemp = ast_get_index_reg_mask(ast, AST_IO_CRTC_PORT, 0xb7, 0x04);
  78                 if (ujcrb7 == jtemp)
  79                         break;
  80         }
  81 }
  82
  83 static struct software_i2c_ops ast_ops = {
  84         .set_sda = set_data,
  85         .set_scl = set_clock,
  86         .get_sda = get_data,
  87         .get_scl = get_clock,
  88 };
  89
  90 int ast_software_i2c_read(struct ast_private *ast_priv, uint8_t edid[128])
  91 {
  92         struct software_i2c_ops *backup;
  93         int ret;
  94
  95         backup = software_i2c[ASPEED_BUS];
  96
  97         software_i2c[ASPEED_BUS] = &ast_ops;
  98
  99         ast = ast_priv;
 100
 101         /* Ast POST pulled SDA and SCL low, recover the bus to a known state */
 102         set_clock(ASPEED_BUS, 1);
 103         set_data(ASPEED_BUS, 1);
 104
 105         udelay(100);
 106
 107         /* Need to reset internal EEPROM counter to 0 */
 108         ret = i2c_read_bytes(ASPEED_BUS, 0x50, 0, edid, 128);
 109
 110         software_i2c[ASPEED_BUS] = backup;
 111
 112         return ret;
 113 }