drivers/misc/cros_ec_spi.c

   1 /*
   2  * Chromium OS cros_ec driver - SPI 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 <cros_ec.h>
  18 #include <spi.h>
  19
  20 int cros_ec_spi_packet(struct cros_ec_dev *dev, int out_bytes, int in_bytes)
  21 {
  22         int rv;
  23
  24         /* Do the transfer */
  25         if (spi_claim_bus(dev->spi)) {
  26                 debug("%s: Cannot claim SPI bus\n", __func__);
  27                 return -1;
  28         }
  29
  30         rv = spi_xfer(dev->spi, max(out_bytes, in_bytes) * 8,
  31                       dev->dout, dev->din,
  32                       SPI_XFER_BEGIN | SPI_XFER_END);
  33
  34         spi_release_bus(dev->spi);
  35
  36         if (rv) {
  37                 debug("%s: Cannot complete SPI transfer\n", __func__);
  38                 return -1;
  39         }
  40
  41         return in_bytes;
  42 }
  43
  44 /**
  45  * Send a command to a LPC CROS_EC device and return the reply.
  46  *
  47  * The device's internal input/output buffers are used.
  48  *
  49  * @param dev           CROS_EC device
  50  * @param cmd           Command to send (EC_CMD_...)
  51  * @param cmd_version   Version of command to send (EC_VER_...)
  52  * @param dout          Output data (may be NULL If dout_len=0)
  53  * @param dout_len      Size of output data in bytes
  54  * @param dinp          Returns pointer to response data. This will be
  55  *                      untouched unless we return a value > 0.
  56  * @param din_len       Maximum size of response in bytes
  57  * @return number of bytes in response, or -1 on error
  58  */
  59 int cros_ec_spi_command(struct cros_ec_dev *dev, uint8_t cmd, int cmd_version,
  60                      const uint8_t *dout, int dout_len,
  61                      uint8_t **dinp, int din_len)
  62 {
  63         int in_bytes = din_len + 4;     /* status, length, checksum, trailer */
  64         uint8_t *out;
  65         uint8_t *p;
  66         int csum, len;
  67         int rv;
  68
  69         if (dev->protocol_version != 2) {
  70                 debug("%s: Unsupported EC protcol version %d\n",
  71                       __func__, dev->protocol_version);
  72                 return -1;
  73         }
  74
  75         /*
  76          * Sanity-check input size to make sure it plus transaction overhead
  77          * fits in the internal device buffer.
  78          */
  79         if (in_bytes > sizeof(dev->din)) {
  80                 debug("%s: Cannot receive %d bytes\n", __func__, din_len);
  81                 return -1;
  82         }
  83
  84         /* We represent message length as a byte */
  85         if (dout_len > 0xff) {
  86                 debug("%s: Cannot send %d bytes\n", __func__, dout_len);
  87                 return -1;
  88         }
  89
  90         /*
  91          * Clear input buffer so we don't get false hits for MSG_HEADER
  92          */
  93         memset(dev->din, '\0', in_bytes);
  94
  95         if (spi_claim_bus(dev->spi)) {
  96                 debug("%s: Cannot claim SPI bus\n", __func__);
  97                 return -1;
  98         }
  99
 100         out = dev->dout;
 101         out[0] = cmd_version;
 102         out[1] = cmd;
 103         out[2] = (uint8_t)dout_len;
 104         memcpy(out + 3, dout, dout_len);
 105         csum = cros_ec_calc_checksum(out, 3)
 106                + cros_ec_calc_checksum(dout, dout_len);
 107         out[3 + dout_len] = (uint8_t)csum;
 108
 109         /*
 110          * Send output data and receive input data starting such that the
 111          * message body will be dword aligned.
 112          */
 113         p = dev->din + sizeof(int64_t) - 2;
 114         len = dout_len + 4;
 115         cros_ec_dump_data("out", cmd, out, len);
 116         rv = spi_xfer(dev->spi, max(len, in_bytes) * 8, out, p,
 117                       SPI_XFER_BEGIN | SPI_XFER_END);
 118
 119         spi_release_bus(dev->spi);
 120
 121         if (rv) {
 122                 debug("%s: Cannot complete SPI transfer\n", __func__);
 123                 return -1;
 124         }
 125
 126         len = min(p[1], din_len);
 127         cros_ec_dump_data("in", -1, p, len + 3);
 128
 129         /* Response code is first byte of message */
 130         if (p[0] != EC_RES_SUCCESS) {
 131                 printf("%s: Returned status %d\n", __func__, p[0]);
 132                 return -(int)(p[0]);
 133         }
 134
 135         /* Check checksum */
 136         csum = cros_ec_calc_checksum(p, len + 2);
 137         if (csum != p[len + 2]) {
 138                 debug("%s: Invalid checksum rx %#02x, calced %#02x\n", __func__,
 139                       p[2 + len], csum);
 140                 return -1;
 141         }
 142
 143         /* Anything else is the response data */
 144         *dinp = p + 2;
 145
 146         return len;
 147 }
 148
 149 int cros_ec_spi_decode_fdt(struct cros_ec_dev *dev, const void *blob)
 150 {
 151         /* Decode interface-specific FDT params */
 152         dev->max_frequency = fdtdec_get_int(blob, dev->node,
 153                                             "spi-max-frequency", 500000);
 154         dev->cs = fdtdec_get_int(blob, dev->node, "reg", 0);
 155
 156         return 0;
 157 }
 158
 159 /**
 160  * Initialize SPI protocol.
 161  *
 162  * @param dev           CROS_EC device
 163  * @param blob          Device tree blob
 164  * @return 0 if ok, -1 on error
 165  */
 166 int cros_ec_spi_init(struct cros_ec_dev *dev, const void *blob)
 167 {
 168         dev->spi = spi_setup_slave_fdt(blob, dev->parent_node, dev->node);
 169         if (!dev->spi) {
 170                 debug("%s: Could not setup SPI slave\n", __func__);
 171                 return -1;
 172         }
 173
 174         return 0;
 175 }