/**************************************************************************** * drivers/spi/spi_bitbang.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 #include #include #include #ifdef CONFIG_SPI_BITBANG /**************************************************************************** * Pre-processor Definitions ****************************************************************************/ /* This file holds the static, device-independent portion of the generic * SPI-bit-bang driver. The full driver consists of 5 files: * * 1. drivers/spi/spi_bitbang.c: This file. This file holds the basic * SPI driver framework and not perform any direct bit-bang operations. * Rather, it will could out to board-specific logic to perform the * low level data transfers. * 2. include/nuttx/spi/spi_bitbang.h: This header file provides the * data types and function prototypes needed to utilize the logic in * this file. * 3. boards////src/: The implementation of the * low-level bit-bang logic resides in some file in the board source * directory. This board-specific logic includes the bit-bang skeleton * logic provided in include/nuttx/spi/spi_bitbang.c. * 4. include/nuttx/spi/spi_bitbang.c. Despite the .c extension, this is * really an included file. It is used in this way: 1) The board- * specific logic in boards////src/ provides * some definitions then 2) includes include/nuttx/spi/spi_bitbang.c. * That file will then use those definitions to implement the low-level * bit-bang logic. The board-specific logic then calls * spi_create_bitbang() in this file to instantiate the complete SPI * driver. * * See include/nuttx/spi/spi_bitbang.c for more detailed usage * information. */ /**************************************************************************** * Private Function Prototypes ****************************************************************************/ /* SPI methods */ static int spi_lock(FAR struct spi_dev_s *dev, bool lock); static void spi_select(FAR struct spi_dev_s *dev, uint32_t devid, bool selected); static uint32_t spi_setfrequency(FAR struct spi_dev_s *dev, uint32_t frequency); static void spi_setmode(FAR struct spi_dev_s *dev, enum spi_mode_e mode); static void spi_setbits(FAR struct spi_dev_s *dev, int nbits); static uint32_t spi_send(FAR struct spi_dev_s *dev, uint32_t wd); static void spi_exchange(FAR struct spi_dev_s *dev, FAR const void *txbuffer, FAR void *rxbuffer, size_t nwords); #ifndef CONFIG_SPI_EXCHANGE static void spi_sndblock(FAR struct spi_dev_s *dev, FAR const void *buffer, size_t nwords); static void spi_recvblock(FAR struct spi_dev_s *dev, FAR void *buffer, size_t nwords); #endif static uint8_t spi_status(FAR struct spi_dev_s *dev, uint32_t devid); #ifdef CONFIG_SPI_CMDDATA static int spi_cmddata(FAR struct spi_dev_s *dev, uint32_t devid, bool cmd); #endif /**************************************************************************** * Private Data ****************************************************************************/ /* SPI driver operations */ static const struct spi_ops_s g_spiops = { spi_lock, /* lock */ spi_select, /* select */ spi_setfrequency, /* setfrequency */ spi_setmode, /* setmode */ spi_setbits, /* setbits */ #ifdef CONFIG_SPI_HWFEATURES 0, /* hwfeatures */ #endif spi_status, /* status */ #ifdef CONFIG_SPI_CMDDATA spi_cmddata, /* cmddata */ #endif spi_send, /* send */ #ifdef CONFIG_SPI_EXCHANGE spi_exchange, /* exchange */ #else spi_sndblock, /* sndblock */ spi_recvblock, /* recvblock */ #endif 0 /* registercallback */ }; /**************************************************************************** * Private Functions ****************************************************************************/ /**************************************************************************** * Name: spi_lock * * Description: * On SPI buses where there are multiple devices, it will be necessary to * lock SPI to have exclusive access to the buses for a sequence of * transfers. The bus should be locked before the chip is selected. After * locking the SPI bus, the caller should then also call the setfrequency, * setbits, and setmode methods to make sure that the SPI is properly * configured for the device. If the SPI bus is being shared, then it * may have been left in an incompatible state. * * Input Parameters: * dev - Device-specific state data * lock - true: Lock spi bus, false: unlock SPI bus * * Returned Value: * None * ****************************************************************************/ static int spi_lock(FAR struct spi_dev_s *dev, bool lock) { FAR struct spi_bitbang_s *priv = (FAR struct spi_bitbang_s *)dev; int ret; spiinfo("lock=%d\n", lock); if (lock) { ret = nxsem_wait_uninterruptible(&priv->exclsem); } else { ret = nxsem_post(&priv->exclsem); } return ret; } /**************************************************************************** * Name: spi_select * * Description: * Set/clear the chip select line for the selected device. * * Input Parameters: * dev - Device-specific state data * devid - Identifies the device to be selected * selected - select or de-select device * * Returned Value: * None * ****************************************************************************/ static void spi_select(FAR struct spi_dev_s *dev, uint32_t devid, bool selected) { FAR struct spi_bitbang_s *priv = (FAR struct spi_bitbang_s *)dev; spiinfo("devid=%d selected=%d\n", devid, selected); DEBUGASSERT(priv && priv->low->select); priv->low->select(priv, devid, selected); } /**************************************************************************** * Name: spi_setfrequency * * Description: * Set the SPI frequency. * * Input Parameters: * dev - Device-specific state data * frequency - The SPI frequency requested * * Returned Value: * Returns the actual frequency selected * ****************************************************************************/ static uint32_t spi_setfrequency(FAR struct spi_dev_s *dev, uint32_t frequency) { FAR struct spi_bitbang_s *priv = (FAR struct spi_bitbang_s *)dev; uint32_t actual; DEBUGASSERT(priv && priv->low->setfrequency); actual = priv->low->setfrequency(priv, frequency); spiinfo("frequency=%d holdtime=%d actual=%d\n", frequency, priv->holdtime, actual); return actual; } /**************************************************************************** * Name: spi_setmode * * Description: * Set the SPI mode. Optional. See enum spi_mode_e for mode definitions * * Input Parameters: * dev - Device-specific state data * mode - The SPI mode requested * * Returned Value: * none * ****************************************************************************/ static void spi_setmode(FAR struct spi_dev_s *dev, enum spi_mode_e mode) { FAR struct spi_bitbang_s *priv = (FAR struct spi_bitbang_s *)dev; DEBUGASSERT(priv && priv->low->setmode); priv->low->setmode(priv, mode); spiinfo("mode=%d exchange=%p\n", mode, priv->exchange); } /**************************************************************************** * Name: spi_setbits * * Description: * Set the number if bits per word. * * Input Parameters: * dev - Device-specific state data * nbits - The number of bits requests * * Returned Value: * none * ****************************************************************************/ static void spi_setbits(FAR struct spi_dev_s *dev, int nbits) { #ifdef CONFIG_SPI_BITBANG_VARWIDTH FAR struct spi_bitbang_s *priv = (FAR struct spi_bitbang_s *)dev; spiinfo("nbits=%d\n", nbits); DEBUGASSERT(priv && nbits > 0 && nbits <= 16); priv->nbits = nbits; #else spiinfo("nbits=%d\n", nbits); DEBUGASSERT(nbits == 8); #endif } /**************************************************************************** * Name: spi_send * * Description: * Exchange one word on SPI * * Input Parameters: * dev - Device-specific state data * wd - The word to send. the size of the data is determined by the * number of bits selected for the SPI interface. * * Returned Value: * response * ****************************************************************************/ static uint32_t spi_send(FAR struct spi_dev_s *dev, uint32_t wd) { FAR struct spi_bitbang_s *priv = (FAR struct spi_bitbang_s *)dev; DEBUGASSERT(priv && priv->low && priv->low->exchange); return priv->low->exchange(priv, (uint16_t)wd); } /**************************************************************************** * Name: spi_exchange * * Description: * Exahange a block of data from SPI. Required. * * Input Parameters: * dev - Device-specific state data * txbuffer - A pointer to the buffer of data to be sent * rxbuffer - A pointer to the buffer in which to receive data * nwords - the length of data that to be exchanged in units of words. * The wordsize is determined by the number of bits-per-word * selected for the SPI interface. If nbits <= 8, the data is * packed into uint8_t's; if nbits >8, the data is packed into * uint16_t's * * Returned Value: * None * ****************************************************************************/ static void spi_exchange(FAR struct spi_dev_s *dev, FAR const void *txbuffer, FAR void *rxbuffer, size_t nwords) { FAR struct spi_bitbang_s *priv = (FAR struct spi_bitbang_s *)dev; FAR const uint8_t *src = (FAR const uint8_t *)txbuffer; FAR uint8_t *dest = (FAR uint8_t *)rxbuffer; uint16_t dataout; uint16_t datain; spiinfo("txbuffer=%p rxbuffer=%p nwords=%d\n", txbuffer, rxbuffer, nwords); DEBUGASSERT(priv && priv->low && priv->low->exchange); /* If there is no data source, send 0xff */ if (!src) { dataout = 0xff; } /* Exchange each word */ while (nwords-- > 0) { /* If there is source data, get the next word from the source */ if (src) { dataout = (uint16_t)*src++; #ifdef CONFIG_SPI_BITBANG_VARWIDTH if (priv->nbits > 8) { #ifdef CONFIG_ENDIAN_BIG dataout <<= 8; dataout |= *src++; #else dataout |= (uint16_t)(*src++) << 8; #endif } #endif } /* Exchange the word of data */ datain = priv->low->exchange(priv, dataout); /* If there is a data sink, transfer the data to the receive buffer */ if (dest) { #ifdef CONFIG_SPI_BITBANG_VARWIDTH if (priv->nbits > 8) { #ifdef CONFIG_ENDIAN_BIG *dest++ = (uint8_t)(datain >> 8); *dest++ = (uint8_t)datain; #else *dest++ = (uint8_t)datain; *dest++ = (uint8_t)(datain >> 8); #endif } #else *dest++ = (uint8_t)datain; #endif } } } /**************************************************************************** * Name: spi_sndblock * * Description: * Send a block of data on SPI * * Input Parameters: * dev - Device-specific state data * buffer - A pointer to the buffer of data to be sent * nwords - the length of data to send from the buffer in number of words. * The wordsize is determined by the number of bits-per-word * selected for the SPI interface. If nbits <= 8, the data is * packed into uint8_t's; if nbits >8, the data is packed into * uint16_t's * * Returned Value: * None * ****************************************************************************/ #ifndef CONFIG_SPI_EXCHANGE static void spi_sndblock(FAR struct spi_dev_s *dev, FAR const void *buffer, size_t nwords) { /* spi_exchange can do this. */ spi_exchange(dev, buffer, NULL, nwords); } #endif /**************************************************************************** * Name: spi_recvblock * * Description: * Revice a block of data from SPI * * Input Parameters: * dev - Device-specific state data * buffer - A pointer to the buffer in which to receive data * nwords - the length of data that can be received in the buffer in number * of words. The wordsize is determined by the number of * bits-per-word selected for the SPI interface. If nbits <= 8, * the data is packed into uint8_t's; if nbits >8, the data is * packed into uint16_t's * * Returned Value: * None * ****************************************************************************/ #ifndef CONFIG_SPI_EXCHANGE static void spi_recvblock(FAR struct spi_dev_s *dev, FAR void *buffer, size_t nwords) { /* spi_exchange can do this. */ spi_exchange(dev, NULL, buffer, nwords); } #endif /**************************************************************************** * Name: spi_status * * Description: * Get status bits associated with the device associated with 'devid' * * Input Parameters: * dev - Device-specific state data * devid - Identifies the device of interest * * Returned Value: * Bit encoded status byte * ****************************************************************************/ static uint8_t spi_status(FAR struct spi_dev_s *dev, uint32_t devid) { FAR struct spi_bitbang_s *priv = (FAR struct spi_bitbang_s *)dev; DEBUGASSERT(priv && priv->low && priv->low->status); return priv->low->status(priv, devid); } /**************************************************************************** * Name: spi_cmddata * * Description: * Control the SPI CMD/DATA like for the device associated with 'devid' * * Input Parameters: * dev - Device-specific state data * devid - Identifies the device of interest * cmd - True:CMD False:DATA * * Returned Value: * OK on success; a negated errno value on failure * ****************************************************************************/ #ifdef CONFIG_SPI_CMDDATA static int spi_cmddata(FAR struct spi_dev_s *dev, uint32_t devid, bool cmd) { FAR struct spi_bitbang_s *priv = (FAR struct spi_bitbang_s *)dev; DEBUGASSERT(priv && priv->low && priv->low->status); return priv->low->cmddata(priv, devid, cmd); } #endif /**************************************************************************** * Public Functions ****************************************************************************/ /**************************************************************************** * Name: spi_create_bitbang * * Description: * Create an instance of the SPI bit-bang driver. * ****************************************************************************/ FAR struct spi_dev_s *spi_create_bitbang(FAR const struct spi_bitbang_ops_s *low) { FAR struct spi_bitbang_s *priv; DEBUGASSERT(low); /* Allocate an instance of the SPI bit bang structure */ priv = (FAR struct spi_bitbang_s *) kmm_zalloc(sizeof(struct spi_bitbang_s)); if (!priv) { spierr("ERROR: Failed to allocate the device structure\n"); return NULL; } /* Initialize the driver structure */ priv->dev.ops = &g_spiops; priv->low = low; #ifdef CONFIG_SPI_BITBANG_VARWIDTH priv->nbits = 8; #endif nxsem_init(&priv->exclsem, 0, 1); /* Select an initial state of mode 0, 8-bits, and 400KHz */ low->setmode(priv, SPIDEV_MODE0); low->setfrequency(priv, 400000); /* And return the initialized driver structure */ return &priv->dev; } #endif /* CONFIG_SPI_BITBANG */