/* * ddc-ci.c: DDC-CI utilities, Linux-only * * Copyright (c) 2015 - 2017, Přemysl Eric Janouch * * Permission to use, copy, modify, and/or distribute this software for any * purpose with or without fee is hereby granted. * * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. * */ // Sources: ddcciv1r1.pdf, i2c-dev.c in Linux, ddccontrol source code, // http://www.boichat.ch/nicolas/ddcci/specs.html was also helpful #include #include #ifndef I2C_FUNC_I2C // Fuck you, openSUSE, for fucking up the previous file, see e.g. // https://github.com/solettaproject/soletta/commit/427f47f #include #endif // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - static void log_message_custom (void *user_data, const char *quote, const char *fmt, va_list ap) { (void) user_data; FILE *stream = stdout; fprintf (stream, PROGRAM_NAME ": "); fputs (quote, stream); vfprintf (stream, fmt, ap); fputs ("\n", stream); } static void wait_ms (long ms) { struct timespec ts = { ms / 1000, (ms % 1000) * 1000 * 1000 }; nanosleep (&ts, NULL); } // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - #define DDC_LENGTH_XOR 0x80 enum { DDC_ADDRESS_HOST = 0x50, ///< Bus master's base address DDC_ADDRESS_DISPLAY = 0x6E ///< The display's base address }; enum { I2C_WRITE, I2C_READ }; enum { DDC_GET_VCP_FEATURE = 0x01, ///< Request info about a feature DDC_GET_VCP_FEATURE_REPLY = 0x02, ///< Feature info response DDC_SET_VCP_FEATURE = 0x03 ///< Set or activate a feature }; enum { VCP_BRIGHTNESS = 0x10, ///< Standard VCP opcode for brightness VCP_CONTRAST = 0x12, ///< Standard VCP opcode for contrast VCP_INPUT_SOURCE = 0x60 ///< Standard VCP opcode for input }; // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - static bool check_edid (int fd, struct error **e) { uint8_t edid_req[] = { 0x00 }; uint8_t buf[8] = ""; struct i2c_msg bufs[] = { { .addr = 0x50, .flags = 0, .len = 1, .buf = edid_req }, { .addr = 0x50, .flags = I2C_M_RD, .len = sizeof buf, .buf = buf }, }; struct i2c_rdwr_ioctl_data data; data.msgs = bufs; data.nmsgs = 2; if (ioctl (fd, I2C_RDWR, &data) < 0) return error_set (e, "%s: %s", "ioctl", strerror (errno)); if (memcmp ("\x00\xFF\xFF\xFF\xFF\xFF\xFF\x00", buf, sizeof buf)) return error_set (e, "invalid EDID"); return true; } static bool is_a_display (int fd, struct error **e) { struct stat st; if (fstat (fd, &st) < 0) return error_set (e, "%s: %s", "fstat", strerror (errno)); unsigned long funcs; if (!(st.st_mode & S_IFCHR) || ioctl (fd, I2C_FUNCS, &funcs) < 0 || !(funcs & I2C_FUNC_I2C)) return error_set (e, "not an I2C device"); return check_edid (fd, e); } // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - static bool ddc_send (int fd, unsigned command, void *args, size_t args_len, struct error **e) { struct str buf = str_make (); str_pack_u8 (&buf, DDC_ADDRESS_HOST | I2C_READ); str_pack_u8 (&buf, DDC_LENGTH_XOR | (args_len + 1)); str_pack_u8 (&buf, command); str_append_data (&buf, args, args_len); unsigned xor = DDC_ADDRESS_DISPLAY; for (size_t i = 0; i < buf.len; i++) xor ^= buf.str[i]; str_pack_u8 (&buf, xor); struct i2c_msg msg = { // The driver unshifts it back .addr = DDC_ADDRESS_DISPLAY >> 1, .flags = 0, .len = buf.len, .buf = (uint8_t *) buf.str, }; struct i2c_rdwr_ioctl_data data; data.msgs = &msg; data.nmsgs = 1; bool failed = ioctl (fd, I2C_RDWR, &data) < 0; str_free (&buf); if (failed) return error_set (e, "%s: %s", "ioctl", strerror (errno)); return true; } static bool ddc_read (int fd, unsigned *command, void *out_buf, size_t *n_read, struct error **e) { uint8_t buf[128] = ""; struct i2c_msg msg = { // The driver unshifts it back .addr = DDC_ADDRESS_DISPLAY >> 1, .flags = I2C_M_RD, .len = sizeof buf, .buf = buf, }; struct i2c_rdwr_ioctl_data data; data.msgs = &msg; data.nmsgs = 1; if (ioctl (fd, I2C_RDWR, &data) < 0) return error_set (e, "%s: %s", "ioctl", strerror (errno)); struct msg_unpacker unpacker = msg_unpacker_make (buf, sizeof buf); uint8_t sender, length, cmd; (void) msg_unpacker_u8 (&unpacker, &sender); (void) msg_unpacker_u8 (&unpacker, &length); (void) msg_unpacker_u8 (&unpacker, &cmd); if (sender != (DDC_ADDRESS_DISPLAY | I2C_WRITE) || !(length & 0x80)) return error_set (e, "invalid response"); if (!(length ^= 0x80)) return error_set (e, "NULL response"); // TODO: also check the checksum *command = cmd; memcpy (out_buf, unpacker.data + unpacker.offset, (*n_read = length - 1)); return true; } // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - struct vcp_feature_readout { uint8_t type; ///< Type of the value int16_t max; ///< Maximum value int16_t cur; ///< Current value }; static bool vcp_get_feature (int fd, uint8_t feature, struct vcp_feature_readout *out, struct error **e) { uint8_t get_req[] = { feature }; if (!ddc_send (fd, DDC_GET_VCP_FEATURE, get_req, sizeof get_req, e)) return false; wait_ms (40); unsigned command = 0; uint8_t buf[128] = ""; size_t len = 0; if (!ddc_read (fd, &command, buf, &len, e)) return false; if (command != DDC_GET_VCP_FEATURE_REPLY || len != 7) return error_set (e, "invalid response"); struct msg_unpacker unpacker = msg_unpacker_make (buf, len); uint8_t result; msg_unpacker_u8 (&unpacker, &result); uint8_t vcp_opcode; msg_unpacker_u8 (&unpacker, &vcp_opcode); msg_unpacker_u8 (&unpacker, &out->type); msg_unpacker_i16 (&unpacker, &out->max); msg_unpacker_i16 (&unpacker, &out->cur); if (result == 0x01) return error_set (e, "error reported by monitor"); if (result != 0x00 || vcp_opcode != feature) return error_set (e, "invalid response"); // These are unsigned but usually just one byte long if (out->max < 0 || out->cur < 0) return error_set (e, "capability range overflow"); return true; }