1 /* 2 * Chromium OS cros_ec driver - SPI interface 3 * 4 * Copyright (c) 2012 The Chromium OS Authors. 5 * See file CREDITS for list of people who contributed to this 6 * project. 7 * 8 * This program is free software; you can redistribute it and/or 9 * modify it under the terms of the GNU General Public License as 10 * published by the Free Software Foundation; either version 2 of 11 * the License, or (at your option) any later version. 12 * 13 * This program is distributed in the hope that it will be useful, 14 * but WITHOUT ANY WARRANTY; without even the implied warranty of 15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 16 * GNU General Public License for more details. 17 * 18 * You should have received a copy of the GNU General Public License 19 * along with this program; if not, write to the Free Software 20 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, 21 * MA 02111-1307 USA 22 */ 23 24 /* 25 * The Matrix Keyboard Protocol driver handles talking to the keyboard 26 * controller chip. Mostly this is for keyboard functions, but some other 27 * things have slipped in, so we provide generic services to talk to the 28 * KBC. 29 */ 30 31 #include <common.h> 32 #include <cros_ec.h> 33 #include <spi.h> 34 35 /** 36 * Send a command to a LPC CROS_EC device and return the reply. 37 * 38 * The device's internal input/output buffers are used. 39 * 40 * @param dev CROS_EC device 41 * @param cmd Command to send (EC_CMD_...) 42 * @param cmd_version Version of command to send (EC_VER_...) 43 * @param dout Output data (may be NULL If dout_len=0) 44 * @param dout_len Size of output data in bytes 45 * @param dinp Returns pointer to response data. This will be 46 * untouched unless we return a value > 0. 47 * @param din_len Maximum size of response in bytes 48 * @return number of bytes in response, or -1 on error 49 */ 50 int cros_ec_spi_command(struct cros_ec_dev *dev, uint8_t cmd, int cmd_version, 51 const uint8_t *dout, int dout_len, 52 uint8_t **dinp, int din_len) 53 { 54 int in_bytes = din_len + 4; /* status, length, checksum, trailer */ 55 uint8_t *out; 56 uint8_t *p; 57 int csum, len; 58 int rv; 59 60 /* 61 * Sanity-check input size to make sure it plus transaction overhead 62 * fits in the internal device buffer. 63 */ 64 if (in_bytes > sizeof(dev->din)) { 65 debug("%s: Cannot receive %d bytes\n", __func__, din_len); 66 return -1; 67 } 68 69 /* We represent message length as a byte */ 70 if (dout_len > 0xff) { 71 debug("%s: Cannot send %d bytes\n", __func__, dout_len); 72 return -1; 73 } 74 75 /* 76 * Clear input buffer so we don't get false hits for MSG_HEADER 77 */ 78 memset(dev->din, '\0', in_bytes); 79 80 if (spi_claim_bus(dev->spi)) { 81 debug("%s: Cannot claim SPI bus\n", __func__); 82 return -1; 83 } 84 85 out = dev->dout; 86 out[0] = cmd_version; 87 out[1] = cmd; 88 out[2] = (uint8_t)dout_len; 89 memcpy(out + 3, dout, dout_len); 90 csum = cros_ec_calc_checksum(out, 3) 91 + cros_ec_calc_checksum(dout, dout_len); 92 out[3 + dout_len] = (uint8_t)csum; 93 94 /* 95 * Send output data and receive input data starting such that the 96 * message body will be dword aligned. 97 */ 98 p = dev->din + sizeof(int64_t) - 2; 99 len = dout_len + 4; 100 cros_ec_dump_data("out", cmd, out, len); 101 rv = spi_xfer(dev->spi, max(len, in_bytes) * 8, out, p, 102 SPI_XFER_BEGIN | SPI_XFER_END); 103 104 spi_release_bus(dev->spi); 105 106 if (rv) { 107 debug("%s: Cannot complete SPI transfer\n", __func__); 108 return -1; 109 } 110 111 len = min(p[1], din_len); 112 cros_ec_dump_data("in", -1, p, len + 3); 113 114 /* Response code is first byte of message */ 115 if (p[0] != EC_RES_SUCCESS) { 116 printf("%s: Returned status %d\n", __func__, p[0]); 117 return -(int)(p[0]); 118 } 119 120 /* Check checksum */ 121 csum = cros_ec_calc_checksum(p, len + 2); 122 if (csum != p[len + 2]) { 123 debug("%s: Invalid checksum rx %#02x, calced %#02x\n", __func__, 124 p[2 + len], csum); 125 return -1; 126 } 127 128 /* Anything else is the response data */ 129 *dinp = p + 2; 130 131 return len; 132 } 133 134 int cros_ec_spi_decode_fdt(struct cros_ec_dev *dev, const void *blob) 135 { 136 /* Decode interface-specific FDT params */ 137 dev->max_frequency = fdtdec_get_int(blob, dev->node, 138 "spi-max-frequency", 500000); 139 dev->cs = fdtdec_get_int(blob, dev->node, "reg", 0); 140 141 return 0; 142 } 143 144 /** 145 * Initialize SPI protocol. 146 * 147 * @param dev CROS_EC device 148 * @param blob Device tree blob 149 * @return 0 if ok, -1 on error 150 */ 151 int cros_ec_spi_init(struct cros_ec_dev *dev, const void *blob) 152 { 153 dev->spi = spi_setup_slave_fdt(blob, dev->parent_node, 154 dev->cs, dev->max_frequency, 0); 155 if (!dev->spi) { 156 debug("%s: Could not setup SPI slave\n", __func__); 157 return -1; 158 } 159 160 return 0; 161 } 162