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 } 176