/**************************************************************************** * drivers/misc/lwl_console.c * * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. The * ASF licenses this file to you under the Apache License, Version 2.0 (the * "License"); you may not use this file except in compliance with the * License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the * License for the specific language governing permissions and limitations * under the License. * ****************************************************************************/ /**************************************************************************** * Included Files ****************************************************************************/ #include #include #include #include #include #include /**************************************************************************** * Pre-processor Definitions ****************************************************************************/ /* Lightweight Link (lwl) * ====================== * * Lightweight bidirectional communication between target and debug host * without any need for additional hardware. * * Works with openOCD and other debuggers that are capable of reading and * writing memory while the target is running. * * Principle of operation is simple; An 'upword' of 32 bits communicates * from the target to the host, a 'downword' of the same size runs in the * opposite direction. These two words can be in any memory that is * read/write access for both the target and the debug host. A simple ping * pong handshake protocol over these words allows up/down link * communication. On the upside no additional integration is needed. On * the downside it may be necessary to feed lwl with cycles to poll for * changes in the downword, depending on the use case. * * Bit configuration * ----------------- * * Downword (Host to target); * * A D U VV XXX * * A 31 1 - Service Active (Set by host) * D 30 1 - Downsense (Toggled when there is data) * U 29 1 - Upsense ack (Toggled to acknowledge receipt of uplink data) * VV 28-27 2 - Valid Octets (Number of octets valid in the message) * XXX 26-24 3 - Port in use (Type of the message) * O2 23-16 8 - Octet 2 * O1 15-08 8 - Octet 1 * O0 07-00 8 - Octet 0 * * Upword (Target to Host); * * A 31 1 - Service Active (Set by device) * D 30 1 - Downsense ack (Toggled to acknowledge receipt of downlink * data) * U 29 1 - Upsense (Toggled when there is data) * VV 28-27 2 - Valid upword octets * XXX 26-24 3 - Port in use (Type of the message) * O2 23-16 8 - Octet 2 * O1 15-08 8 - Octet 1 * O0 07-00 8 - Octet 0 * */ /* Protocol bits */ #define LWL_GETACTIVE(x) (((x) & (1 << 31)) != 0) #define LWL_ACTIVE(x) (((x)&1) << 31) #define LWL_DNSENSEBIT (1 << 30) #define LWL_DNSENSE(x) ((x)&LWL_DNSENSEBIT) #define LWL_UPSENSEBIT (1 << 29) #define LWL_UPSENSE(x) ((x)&LWL_UPSENSEBIT) #define LWL_SENSEMASK (3 << 29) #define LWL_GETOCTVAL(x) (((x) >> 27) & 3) #define LWL_OCTVAL(x) (((x)&3) << 27) #define LWL_GETPORT(x) (((x) >> 24) & 7) #define LWL_PORT(x) (((x)&7) << 24) #define LWL_PORT_CONSOLE 1 #define LWL_ID_SIG 0x7216A318 /**************************************************************************** * Private Function Prototypes ****************************************************************************/ static ssize_t lwlconsole_read(FAR struct file *filep, FAR char *buffer, size_t buflen); static ssize_t lwlconsole_write(FAR struct file *filep, FAR const char *buffer, size_t buflen); /**************************************************************************** * Private Data ****************************************************************************/ struct lwl_entry_s { uint32_t sig; /* Location signature */ volatile uint32_t downword; /* Host to Target word */ uint32_t upword; /* Target to Host word */ }; static struct lwl_entry_s g_d = { LWL_ID_SIG }; static const struct file_operations g_consoleops = { NULL, /* open */ NULL, /* close */ lwlconsole_read, /* read */ lwlconsole_write, /* write */ }; /**************************************************************************** * Private Functions ****************************************************************************/ static bool linkactive(void) { return (LWL_GETACTIVE(g_d.downword) != 0); } static bool writeword(uint32_t newupword) { /* Check link is active */ if (!linkactive()) { return false; } /* Spin waiting for previous data to be collected */ while (LWL_UPSENSE(g_d.downword) != LWL_UPSENSE(g_d.upword)) { } /* Load new data, toggling UPSENSE bit to show it is new */ g_d.upword = LWL_DNSENSE(g_d.upword) | newupword | (LWL_UPSENSE(g_d.upword) ? 0 : LWL_UPSENSEBIT); return true; } static bool write8bits(uint8_t port, uint8_t val) { /* Prepare new word */ uint32_t newupword = LWL_ACTIVE(true) | LWL_OCTVAL(1) | LWL_PORT(port) | (val & 0xff); return writeword(newupword); } static bool write16bits(uint8_t port, uint32_t val) { /* Prepare new word */ uint32_t newupword = LWL_ACTIVE(true) | LWL_OCTVAL(2) | LWL_PORT(port) | (val & 0xffff); return writeword(newupword); } static bool write24bits(uint8_t port, uint32_t val) { /* Prepare new word */ uint32_t newupword = LWL_ACTIVE(true) | LWL_OCTVAL(3) | LWL_PORT(port) | (val & 0xffffff); return writeword(newupword); } static bool read8bits(uint8_t port, FAR uint8_t *store) { if (!linkactive()) { return false; } /* Spin waiting for a byte to be received */ while (LWL_DNSENSE(g_d.downword) == LWL_DNSENSE(g_d.upword)) { } *store = g_d.downword & 255; /* Flip the bit to indicate the datum is read */ g_d.upword = (g_d.upword & ~LWL_DNSENSEBIT) | LWL_DNSENSE(g_d.downword); return true; } /**************************************************************************** * Name: lwlconsole_read ****************************************************************************/ static ssize_t lwlconsole_read(FAR struct file *filep, FAR char *buffer, size_t buflen) { if (buflen == 0) { return 0; } if (!read8bits(LWL_PORT_CONSOLE, (FAR uint8_t *) buffer)) { return 0; } return 1; } /**************************************************************************** * Name: lwlconsole_write ****************************************************************************/ static ssize_t lwlconsole_write(FAR struct file *filep, FAR const char *buffer, size_t buflen) { uint32_t oc = 0; while (buflen) { switch (buflen) { case 0: return oc; case 1: if (write8bits(LWL_PORT_CONSOLE, buffer[0])) { oc++; buffer++; buflen--; } break; case 2: if (write16bits(LWL_PORT_CONSOLE, buffer[0] | (buffer[1] << 8))) { oc += 2; buffer += 2; buflen -= 2; } break; default: if (write24bits(LWL_PORT_CONSOLE, buffer[0] | (buffer[1] << 8) | (buffer[2] << 16))) { oc += 3; buffer += 3; buflen -= 3; } break; } } return oc; } /**************************************************************************** * Public Functions ****************************************************************************/ /**************************************************************************** * Name: lwlconsole_init ****************************************************************************/ void lwlconsole_init(void) { register_driver("/dev/console", &g_consoleops, 0666, NULL); }