drivers/misc/cros_ec_lpc.c

   1 /*
   2  * Chromium OS cros_ec driver - LPC interface
   3  *
   4  * Copyright (c) 2012 The Chromium OS Authors.
   5  *
   6  * SPDX-License-Identifier:     GPL-2.0+
   7  */
   8
   9 /*
  10  * The Matrix Keyboard Protocol driver handles talking to the keyboard
  11  * controller chip. Mostly this is for keyboard functions, but some other
  12  * things have slipped in, so we provide generic services to talk to the
  13  * KBC.
  14  */
  15
  16 #include <common.h>
  17 #include <command.h>
  18 #include <cros_ec.h>
  19 #include <asm/io.h>
  20
  21 #ifdef DEBUG_TRACE
  22 #define debug_trace(fmt, b...)  debug(fmt, ##b)
  23 #else
  24 #define debug_trace(fmt, b...)
  25 #endif
  26
  27 static int wait_for_sync(struct cros_ec_dev *dev)
  28 {
  29         unsigned long start;
  30
  31         start = get_timer(0);
  32         while (inb(EC_LPC_ADDR_HOST_CMD) & EC_LPC_STATUS_BUSY_MASK) {
  33                 if (get_timer(start) > 1000) {
  34                         debug("%s: Timeout waiting for CROS_EC sync\n",
  35                               __func__);
  36                         return -1;
  37                 }
  38         }
  39
  40         return 0;
  41 }
  42
  43 int cros_ec_lpc_command(struct cros_ec_dev *dev, uint8_t cmd, int cmd_version,
  44                      const uint8_t *dout, int dout_len,
  45                      uint8_t **dinp, int din_len)
  46 {
  47         const int cmd_addr = EC_LPC_ADDR_HOST_CMD;
  48         const int data_addr = EC_LPC_ADDR_HOST_DATA;
  49         const int args_addr = EC_LPC_ADDR_HOST_ARGS;
  50         const int param_addr = EC_LPC_ADDR_HOST_PARAM;
  51
  52         struct ec_lpc_host_args args;
  53         uint8_t *d;
  54         int csum;
  55         int i;
  56
  57         if (dout_len > EC_HOST_PARAM_SIZE) {
  58                 debug("%s: Cannot send %d bytes\n", __func__, dout_len);
  59                 return -1;
  60         }
  61
  62         /* Fill in args */
  63         args.flags = EC_HOST_ARGS_FLAG_FROM_HOST;
  64         args.command_version = cmd_version;
  65         args.data_size = dout_len;
  66
  67         /* Calculate checksum */
  68         csum = cmd + args.flags + args.command_version + args.data_size;
  69         for (i = 0, d = (uint8_t *)dout; i < dout_len; i++, d++)
  70                 csum += *d;
  71
  72         args.checksum = (uint8_t)csum;
  73
  74         if (wait_for_sync(dev)) {
  75                 debug("%s: Timeout waiting ready\n", __func__);
  76                 return -1;
  77         }
  78
  79         /* Write args */
  80         for (i = 0, d = (uint8_t *)&args; i < sizeof(args); i++, d++)
  81                 outb(*d, args_addr + i);
  82
  83         /* Write data, if any */
  84         debug_trace("cmd: %02x, ver: %02x", cmd, cmd_version);
  85         for (i = 0, d = (uint8_t *)dout; i < dout_len; i++, d++) {
  86                 outb(*d, param_addr + i);
  87                 debug_trace("%02x ", *d);
  88         }
  89
  90         outb(cmd, cmd_addr);
  91         debug_trace("\n");
  92
  93         if (wait_for_sync(dev)) {
  94                 debug("%s: Timeout waiting for response\n", __func__);
  95                 return -1;
  96         }
  97
  98         /* Check result */
  99         i = inb(data_addr);
 100         if (i) {
 101                 debug("%s: CROS_EC result code %d\n", __func__, i);
 102                 return -i;
 103         }
 104
 105         /* Read back args */
 106         for (i = 0, d = (uint8_t *)&args; i < sizeof(args); i++, d++)
 107                 *d = inb(args_addr + i);
 108
 109         /*
 110          * If EC didn't modify args flags, then somehow we sent a new-style
 111          * command to an old EC, which means it would have read its params
 112          * from the wrong place.
 113          */
 114         if (!(args.flags & EC_HOST_ARGS_FLAG_TO_HOST)) {
 115                 debug("%s: CROS_EC protocol mismatch\n", __func__);
 116                 return -EC_RES_INVALID_RESPONSE;
 117         }
 118
 119         if (args.data_size > din_len) {
 120                 debug("%s: CROS_EC returned too much data %d > %d\n",
 121                       __func__, args.data_size, din_len);
 122                 return -EC_RES_INVALID_RESPONSE;
 123         }
 124
 125         /* Read data, if any */
 126         for (i = 0, d = (uint8_t *)dev->din; i < args.data_size; i++, d++) {
 127                 *d = inb(param_addr + i);
 128                 debug_trace("%02x ", *d);
 129         }
 130         debug_trace("\n");
 131
 132         /* Verify checksum */
 133         csum = cmd + args.flags + args.command_version + args.data_size;
 134         for (i = 0, d = (uint8_t *)dev->din; i < args.data_size; i++, d++)
 135                 csum += *d;
 136
 137         if (args.checksum != (uint8_t)csum) {
 138                 debug("%s: CROS_EC response has invalid checksum\n", __func__);
 139                 return -EC_RES_INVALID_CHECKSUM;
 140         }
 141         *dinp = dev->din;
 142
 143         /* Return actual amount of data received */
 144         return args.data_size;
 145 }
 146
 147 /**
 148  * Initialize LPC protocol.
 149  *
 150  * @param dev           CROS_EC device
 151  * @param blob          Device tree blob
 152  * @return 0 if ok, -1 on error
 153  */
 154 int cros_ec_lpc_init(struct cros_ec_dev *dev, const void *blob)
 155 {
 156         int byte, i;
 157
 158         /* See if we can find an EC at the other end */
 159         byte = 0xff;
 160         byte &= inb(EC_LPC_ADDR_HOST_CMD);
 161         byte &= inb(EC_LPC_ADDR_HOST_DATA);
 162         for (i = 0; i < EC_HOST_PARAM_SIZE && (byte == 0xff); i++)
 163                 byte &= inb(EC_LPC_ADDR_HOST_PARAM + i);
 164         if (byte == 0xff) {
 165                 debug("%s: CROS_EC device not found on LPC bus\n",
 166                         __func__);
 167                 return -1;
 168         }
 169
 170         return 0;
 171 }
 172
 173 /*
 174  * Test if LPC command args are supported.
 175  *
 176  * The cheapest way to do this is by looking for the memory-mapped
 177  * flag.  This is faster than sending a new-style 'hello' command and
 178  * seeing whether the EC sets the EC_HOST_ARGS_FLAG_FROM_HOST flag
 179  * in args when it responds.
 180  */
 181 int cros_ec_lpc_check_version(struct cros_ec_dev *dev)
 182 {
 183         if (inb(EC_LPC_ADDR_MEMMAP + EC_MEMMAP_ID) == 'E' &&
 184                         inb(EC_LPC_ADDR_MEMMAP + EC_MEMMAP_ID + 1)
 185                                 == 'C' &&
 186                         (inb(EC_LPC_ADDR_MEMMAP +
 187                                 EC_MEMMAP_HOST_CMD_FLAGS) &
 188                                 EC_HOST_CMD_FLAG_LPC_ARGS_SUPPORTED)) {
 189                 return 0;
 190         }
 191
 192         printf("%s: ERROR: old EC interface not supported\n", __func__);
 193         return -1;
 194 }