drivers/misc/cros_ec_i2c.c

   1 /*
   2  * Chromium OS cros_ec driver - I2C 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 <dm.h>
  18 #include <i2c.h>
  19 #include <cros_ec.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 cros_ec_i2c_command(struct udevice *udev, uint8_t cmd,
  28                                int cmd_version, const uint8_t *dout,
  29                                int dout_len, uint8_t **dinp, int din_len)
  30 {
  31         struct cros_ec_dev *dev = udev->uclass_priv;
  32         /* version8, cmd8, arglen8, out8[dout_len], csum8 */
  33         int out_bytes = dout_len + 4;
  34         /* response8, arglen8, in8[din_len], checksum8 */
  35         int in_bytes = din_len + 3;
  36         uint8_t *ptr;
  37         /* Receive input data, so that args will be dword aligned */
  38         uint8_t *in_ptr;
  39         int len, csum, ret;
  40
  41         /*
  42          * Sanity-check I/O sizes given transaction overhead in internal
  43          * buffers.
  44          */
  45         if (out_bytes > sizeof(dev->dout)) {
  46                 debug("%s: Cannot send %d bytes\n", __func__, dout_len);
  47                 return -1;
  48         }
  49         if (in_bytes > sizeof(dev->din)) {
  50                 debug("%s: Cannot receive %d bytes\n", __func__, din_len);
  51                 return -1;
  52         }
  53         assert(dout_len >= 0);
  54         assert(dinp);
  55
  56         /*
  57          * Copy command and data into output buffer so we can do a single I2C
  58          * burst transaction.
  59          */
  60         ptr = dev->dout;
  61
  62         /*
  63          * in_ptr starts of pointing to a dword-aligned input data buffer.
  64          * We decrement it back by the number of header bytes we expect to
  65          * receive, so that the first parameter of the resulting input data
  66          * will be dword aligned.
  67          */
  68         in_ptr = dev->din + sizeof(int64_t);
  69
  70         if (dev->protocol_version != 2) {
  71                 /* Something we don't support */
  72                 debug("%s: Protocol version %d unsupported\n",
  73                       __func__, dev->protocol_version);
  74                 return -1;
  75         }
  76
  77         *ptr++ = EC_CMD_VERSION0 + cmd_version;
  78         *ptr++ = cmd;
  79         *ptr++ = dout_len;
  80         in_ptr -= 2;    /* Expect status, length bytes */
  81
  82         memcpy(ptr, dout, dout_len);
  83         ptr += dout_len;
  84
  85         *ptr++ = (uint8_t)
  86                 cros_ec_calc_checksum(dev->dout, dout_len + 3);
  87
  88         /* Send output data */
  89         cros_ec_dump_data("out", -1, dev->dout, out_bytes);
  90         ret = dm_i2c_write(udev, 0, dev->dout, out_bytes);
  91         if (ret) {
  92                 debug("%s: Cannot complete I2C write to %s\n", __func__,
  93                       udev->name);
  94                 ret = -1;
  95         }
  96
  97         if (!ret) {
  98                 ret = dm_i2c_read(udev, 0, in_ptr, in_bytes);
  99                 if (ret) {
 100                         debug("%s: Cannot complete I2C read from %s\n",
 101                               __func__, udev->name);
 102                         ret = -1;
 103                 }
 104         }
 105
 106         if (*in_ptr != EC_RES_SUCCESS) {
 107                 debug("%s: Received bad result code %d\n", __func__, *in_ptr);
 108                 return -(int)*in_ptr;
 109         }
 110
 111         len = in_ptr[1];
 112         if (len + 3 > sizeof(dev->din)) {
 113                 debug("%s: Received length %#02x too large\n",
 114                       __func__, len);
 115                 return -1;
 116         }
 117         csum = cros_ec_calc_checksum(in_ptr, 2 + len);
 118         if (csum != in_ptr[2 + len]) {
 119                 debug("%s: Invalid checksum rx %#02x, calced %#02x\n",
 120                       __func__, in_ptr[2 + din_len], csum);
 121                 return -1;
 122         }
 123         din_len = min(din_len, len);
 124         cros_ec_dump_data("in", -1, in_ptr, din_len + 3);
 125
 126         /* Return pointer to dword-aligned input data, if any */
 127         *dinp = dev->din + sizeof(int64_t);
 128
 129         return din_len;
 130 }
 131
 132 static int cros_ec_probe(struct udevice *dev)
 133 {
 134         return cros_ec_register(dev);
 135 }
 136
 137 static struct dm_cros_ec_ops cros_ec_ops = {
 138         .command = cros_ec_i2c_command,
 139 };
 140
 141 static const struct udevice_id cros_ec_ids[] = {
 142         { .compatible = "google,cros-ec" },
 143         { }
 144 };
 145
 146 U_BOOT_DRIVER(cros_ec_i2c) = {
 147         .name           = "cros_ec",
 148         .id             = UCLASS_CROS_EC,
 149         .of_match       = cros_ec_ids,
 150         .probe          = cros_ec_probe,
 151         .ops            = &cros_ec_ops,
 152 };