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