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max5478.c (3233B)

      1 /*
      2  * 
      3  * This license is set out in https://raw.githubusercontent.com/Broadcom-Network-Switching-Software/OpenBCM/master/Legal/LICENSE file.
      4  * 
      5  * Copyright 2007-2019 Broadcom Inc. All rights reserved.
      6  * All Rights Reserved.$
      7  *
      8  * BCM56xx I2C Device Driver for Maxim 5478 Digital Potentiometer
      9  * The Maxim 5478 digital potentiometer is used to adjust the voltage
     10  * divider in SDK baseboards. See the Maxim 5478 datasheet for more info.
     11  */
     12 #include <sal/types.h>
     13 #include <soc/debug.h>
     14 #include <soc/drv.h>
     15 #include <soc/error.h>
     16 #include <soc/i2c.h>
     17 #include <sal/core/libc.h>
     18 #include <shared/bsl.h>
     19 /* Command byte - see Max5478, Table 2 */
     20 #define MAX5478_CMD_WIPER_A_VREG            0x11
     21 #define MAX5478_CMD_WIPER_A_VREG_X_NVREG    0x51
     22 #define MAX5478_CMD_WIPER_B_CMD             0x12
     23 #define MAX5478_CMD_WIPER_B_VREG_X_NVREG    0x52
     24 
     25 STATIC int
     26 max5478_read(int unit, int devno,
     27 	  uint16 addr, uint8* data, uint32* len)
     28 {
     29     COMPILER_REFERENCE(unit);
     30     COMPILER_REFERENCE(devno);
     31     COMPILER_REFERENCE(addr);
     32     COMPILER_REFERENCE(data);
     33     COMPILER_REFERENCE(len);
     34 
     35     return SOC_E_NONE;
     36 }
     37 
     38 STATIC int
     39 max5478_write(int unit, int devno,
     40 	   uint16 addr, uint8* data, uint32 len)
     41 {
     42     int rv = SOC_E_NONE;
     43     return rv;
     44 }
     45 
     46 STATIC int
     47 max5478_ioctl(int unit, int devno,
     48               int request, void* data, int len)
     49 {
     50     int rv = SOC_E_NONE;
     51     uint16 msg0;
     52     uint8  msg1;
     53     max5478_t *params;
     54 
     55     switch (request) {
     56     case I2C_POT_IOC_SET:
     57         params = (max5478_t *)data;
     58         switch (params->wiper) {
     59         case I2C_POT_MSG_WIPER_A:
     60              msg0 = MAX5478_CMD_WIPER_A_VREG;
     61              msg1 = MAX5478_CMD_WIPER_A_VREG_X_NVREG;
     62             break;
     63 
     64         case I2C_POT_MSG_WIPER_B:
     65             msg0 = MAX5478_CMD_WIPER_B_CMD;
     66             msg1 = MAX5478_CMD_WIPER_B_VREG_X_NVREG;
     67             break;
     68 
     69         default:
     70             LOG_VERBOSE(BSL_LS_SOC_COMMON,
     71                         (BSL_META_U(unit,
     72                                     "POT%d: invalid wiper %d\n"),
     73                          devno, params->wiper));
     74             return SOC_E_PARAM;
     75         }
     76 
     77         /* Command byte VREG + data byte */
     78         msg0 = (msg0 << 8) | params->value;
     79         rv = soc_i2c_write_word(unit, soc_i2c_addr(unit, devno), msg0);
     80         if (rv == SOC_E_NONE) {
     81             soc_i2c_device(unit, devno)->tbyte +=2;
     82         }
     83 
     84         /* Transfer VREG to NVREG */
     85         rv = soc_i2c_write_byte(unit, soc_i2c_addr(unit, devno), msg1);
     86         if (rv == SOC_E_NONE) {
     87             soc_i2c_device(unit, devno)->tbyte++;
     88         }
     89 
     90         break;
     91 
     92     default:
     93         LOG_VERBOSE(BSL_LS_SOC_COMMON,
     94                     (BSL_META_U(unit,
     95                                 "POT%d: invalid request %d\n"),
     96                      devno, request));
     97         return SOC_E_PARAM;
     98     }
     99     return rv;
    100 }
    101 
    102 STATIC int
    103 max5478_init(int unit, int devno,
    104 	  void* data, int len)
    105 {
    106     soc_i2c_devdesc_set(unit, devno, "Maxim 5478 Digital Potentiometer");
    107 
    108     return SOC_E_NONE;
    109 }
    110 
    111 /* MAX5478 Clock Chip Driver callout */
    112 i2c_driver_t _soc_i2c_max5478_driver = {
    113     0x0, 0x0, /* System assigned bytes */
    114     MAX5478_DEVICE_TYPE,
    115     max5478_read,
    116     max5478_write,
    117     max5478_ioctl,
    118     max5478_init,
    119     NULL,
    120 };