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 /**
  44  * Send a command to a LPC CROS_EC device and return the reply.
  45  *
  46  * The device's internal input/output buffers are used.
  47  *
  48  * @param dev           CROS_EC device
  49  * @param cmd           Command to send (EC_CMD_...)
  50  * @param cmd_version   Version of command to send (EC_VER_...)
  51  * @param dout          Output data (may be NULL If dout_len=0)
  52  * @param dout_len      Size of output data in bytes
  53  * @param dinp          Place to put pointer to response data
  54  * @param din_len       Maximum size of response in bytes
  55  * @return number of bytes in response, or -1 on error
  56  */
  57 static int old_lpc_command(struct cros_ec_dev *dev, uint8_t cmd,
  58                      const uint8_t *dout, int dout_len,
  59                      uint8_t **dinp, int din_len)
  60 {
  61         int ret, i;
  62
  63         if (dout_len > EC_OLD_PARAM_SIZE) {
  64                 debug("%s: Cannot send %d bytes\n", __func__, dout_len);
  65                 return -1;
  66         }
  67
  68         if (din_len > EC_OLD_PARAM_SIZE) {
  69                 debug("%s: Cannot receive %d bytes\n", __func__, din_len);
  70                 return -1;
  71         }
  72
  73         if (wait_for_sync(dev)) {
  74                 debug("%s: Timeout waiting ready\n", __func__);
  75                 return -1;
  76         }
  77
  78         debug_trace("cmd: %02x, ", cmd);
  79         for (i = 0; i < dout_len; i++) {
  80                 debug_trace("%02x ", dout[i]);
  81                 outb(dout[i], EC_LPC_ADDR_OLD_PARAM + i);
  82         }
  83         outb(cmd, EC_LPC_ADDR_HOST_CMD);
  84         debug_trace("\n");
  85
  86         if (wait_for_sync(dev)) {
  87                 debug("%s: Timeout waiting ready\n", __func__);
  88                 return -1;
  89         }
  90
  91         ret = inb(EC_LPC_ADDR_HOST_DATA);
  92         if (ret) {
  93                 debug("%s: CROS_EC result code %d\n", __func__, ret);
  94                 return -ret;
  95         }
  96
  97         debug_trace("resp: %02x, ", ret);
  98         for (i = 0; i < din_len; i++) {
  99                 dev->din[i] = inb(EC_LPC_ADDR_OLD_PARAM + i);
 100                 debug_trace("%02x ", dev->din[i]);
 101         }
 102         debug_trace("\n");
 103         *dinp = dev->din;
 104
 105         return din_len;
 106 }
 107
 108 int cros_ec_lpc_command(struct cros_ec_dev *dev, uint8_t cmd, int cmd_version,
 109                      const uint8_t *dout, int dout_len,
 110                      uint8_t **dinp, int din_len)
 111 {
 112         const int cmd_addr = EC_LPC_ADDR_HOST_CMD;
 113         const int data_addr = EC_LPC_ADDR_HOST_DATA;
 114         const int args_addr = EC_LPC_ADDR_HOST_ARGS;
 115         const int param_addr = EC_LPC_ADDR_HOST_PARAM;
 116
 117         struct ec_lpc_host_args args;
 118         uint8_t *d;
 119         int csum;
 120         int i;
 121
 122         /* Fall back to old-style command interface if args aren't supported */
 123         if (!dev->cmd_version_is_supported)
 124                 return old_lpc_command(dev, cmd, dout, dout_len, dinp,
 125                                        din_len);
 126
 127         if (dout_len > EC_HOST_PARAM_SIZE) {
 128                 debug("%s: Cannot send %d bytes\n", __func__, dout_len);
 129                 return -1;
 130         }
 131
 132         /* Fill in args */
 133         args.flags = EC_HOST_ARGS_FLAG_FROM_HOST;
 134         args.command_version = cmd_version;
 135         args.data_size = dout_len;
 136
 137         /* Calculate checksum */
 138         csum = cmd + args.flags + args.command_version + args.data_size;
 139         for (i = 0, d = (uint8_t *)dout; i < dout_len; i++, d++)
 140                 csum += *d;
 141
 142         args.checksum = (uint8_t)csum;
 143
 144         if (wait_for_sync(dev)) {
 145                 debug("%s: Timeout waiting ready\n", __func__);
 146                 return -1;
 147         }
 148
 149         /* Write args */
 150         for (i = 0, d = (uint8_t *)&args; i < sizeof(args); i++, d++)
 151                 outb(*d, args_addr + i);
 152
 153         /* Write data, if any */
 154         debug_trace("cmd: %02x, ver: %02x", cmd, cmd_version);
 155         for (i = 0, d = (uint8_t *)dout; i < dout_len; i++, d++) {
 156                 outb(*d, param_addr + i);
 157                 debug_trace("%02x ", *d);
 158         }
 159
 160         outb(cmd, cmd_addr);
 161         debug_trace("\n");
 162
 163         if (wait_for_sync(dev)) {
 164                 debug("%s: Timeout waiting for response\n", __func__);
 165                 return -1;
 166         }
 167
 168         /* Check result */
 169         i = inb(data_addr);
 170         if (i) {
 171                 debug("%s: CROS_EC result code %d\n", __func__, i);
 172                 return -i;
 173         }
 174
 175         /* Read back args */
 176         for (i = 0, d = (uint8_t *)&args; i < sizeof(args); i++, d++)
 177                 *d = inb(args_addr + i);
 178
 179         /*
 180          * If EC didn't modify args flags, then somehow we sent a new-style
 181          * command to an old EC, which means it would have read its params
 182          * from the wrong place.
 183          */
 184         if (!(args.flags & EC_HOST_ARGS_FLAG_TO_HOST)) {
 185                 debug("%s: CROS_EC protocol mismatch\n", __func__);
 186                 return -EC_RES_INVALID_RESPONSE;
 187         }
 188
 189         if (args.data_size > din_len) {
 190                 debug("%s: CROS_EC returned too much data %d > %d\n",
 191                       __func__, args.data_size, din_len);
 192                 return -EC_RES_INVALID_RESPONSE;
 193         }
 194
 195         /* Read data, if any */
 196         for (i = 0, d = (uint8_t *)dev->din; i < args.data_size; i++, d++) {
 197                 *d = inb(param_addr + i);
 198                 debug_trace("%02x ", *d);
 199         }
 200         debug_trace("\n");
 201
 202         /* Verify checksum */
 203         csum = cmd + args.flags + args.command_version + args.data_size;
 204         for (i = 0, d = (uint8_t *)dev->din; i < args.data_size; i++, d++)
 205                 csum += *d;
 206
 207         if (args.checksum != (uint8_t)csum) {
 208                 debug("%s: CROS_EC response has invalid checksum\n", __func__);
 209                 return -EC_RES_INVALID_CHECKSUM;
 210         }
 211         *dinp = dev->din;
 212
 213         /* Return actual amount of data received */
 214         return args.data_size;
 215 }
 216
 217 /**
 218  * Initialize LPC protocol.
 219  *
 220  * @param dev           CROS_EC device
 221  * @param blob          Device tree blob
 222  * @return 0 if ok, -1 on error
 223  */
 224 int cros_ec_lpc_init(struct cros_ec_dev *dev, const void *blob)
 225 {
 226         int byte, i;
 227
 228         /* See if we can find an EC at the other end */
 229         byte = 0xff;
 230         byte &= inb(EC_LPC_ADDR_HOST_CMD);
 231         byte &= inb(EC_LPC_ADDR_HOST_DATA);
 232         for (i = 0; i < EC_HOST_PARAM_SIZE && (byte == 0xff); i++)
 233                 byte &= inb(EC_LPC_ADDR_HOST_PARAM + i);
 234         if (byte == 0xff) {
 235                 debug("%s: CROS_EC device not found on LPC bus\n",
 236                         __func__);
 237                 return -1;
 238         }
 239
 240         return 0;
 241 }
 242
 243 /*
 244  * Test if LPC command args are supported.
 245  *
 246  * The cheapest way to do this is by looking for the memory-mapped
 247  * flag.  This is faster than sending a new-style 'hello' command and
 248  * seeing whether the EC sets the EC_HOST_ARGS_FLAG_FROM_HOST flag
 249  * in args when it responds.
 250  */
 251 int cros_ec_lpc_check_version(struct cros_ec_dev *dev)
 252 {
 253         if (inb(EC_LPC_ADDR_MEMMAP + EC_MEMMAP_ID) == 'E' &&
 254                         inb(EC_LPC_ADDR_MEMMAP + EC_MEMMAP_ID + 1)
 255                                 == 'C' &&
 256                         (inb(EC_LPC_ADDR_MEMMAP +
 257                                 EC_MEMMAP_HOST_CMD_FLAGS) &
 258                                 EC_HOST_CMD_FLAG_LPC_ARGS_SUPPORTED)) {
 259                 dev->cmd_version_is_supported = 1;
 260         } else {
 261                 /* We are going to use the old IO ports */
 262                 dev->cmd_version_is_supported = 0;
 263         }
 264         debug("lpc: version %s\n", dev->cmd_version_is_supported ?
 265                         "new" : "old");
 266
 267         return 0;
 268 }