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