--- /dev/null
+/*
+ * Copyright (C) 2006 Michael Brown <mbrown@fensystems.co.uk>.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+#include <stddef.h>
+#include <stdint.h>
+#include <string.h>
+#include <byteswap.h>
+#include <errno.h>
+#include <assert.h>
+#include <unistd.h>
+#include <ipxe/bitbash.h>
+#include <ipxe/spi_bit.h>
+
+/** @file
+ *
+ * SPI bit-bashing interface
+ *
+ */
+
+/** Delay between SCLK changes and around SS changes */
+static void spi_bit_delay ( void ) {
+ udelay ( SPI_BIT_UDELAY );
+}
+
+/** Chip select line will be asserted */
+#define SELECT_SLAVE 0
+
+/** Chip select line will be deasserted */
+#define DESELECT_SLAVE SPI_MODE_SSPOL
+
+/**
+ * Select/deselect slave
+ *
+ * @v spibit SPI bit-bashing interface
+ * @v slave Slave number
+ * @v state Slave select state
+ *
+ * @c state must be @c SELECT_SLAVE or @c DESELECT_SLAVE.
+ */
+static void spi_bit_set_slave_select ( struct spi_bit_basher *spibit,
+ unsigned int slave,
+ unsigned int state ) {
+ struct bit_basher *basher = &spibit->basher;
+
+ state ^= ( spibit->bus.mode & SPI_MODE_SSPOL );
+ DBGC2 ( spibit, "SPIBIT %p setting slave %d select %s\n",
+ spibit, slave, ( state ? "high" : "low" ) );
+
+ spi_bit_delay();
+ write_bit ( basher, SPI_BIT_SS ( slave ), state );
+ spi_bit_delay();
+}
+
+/**
+ * Transfer bits over SPI bit-bashing bus
+ *
+ * @v bus SPI bus
+ * @v data_out TX data buffer (or NULL)
+ * @v data_in RX data buffer (or NULL)
+ * @v len Length of transfer (in @b bits)
+ * @v endianness Endianness of this data transfer
+ *
+ * This issues @c len clock cycles on the SPI bus, shifting out data
+ * from the @c data_out buffer to the MOSI line and shifting in data
+ * from the MISO line to the @c data_in buffer. If @c data_out is
+ * NULL, then the data sent will be all zeroes. If @c data_in is
+ * NULL, then the incoming data will be discarded.
+ */
+static void spi_bit_transfer ( struct spi_bit_basher *spibit,
+ const void *data_out, void *data_in,
+ unsigned int len, int endianness ) {
+ struct spi_bus *bus = &spibit->bus;
+ struct bit_basher *basher = &spibit->basher;
+ unsigned int sclk = ( ( bus->mode & SPI_MODE_CPOL ) ? 1 : 0 );
+ unsigned int cpha = ( ( bus->mode & SPI_MODE_CPHA ) ? 1 : 0 );
+ unsigned int bit_offset;
+ unsigned int byte_offset;
+ unsigned int byte_mask;
+ unsigned int bit;
+ unsigned int step;
+
+ DBGC2 ( spibit, "SPIBIT %p transferring %d bits in mode %#x\n",
+ spibit, len, bus->mode );
+
+ for ( step = 0 ; step < ( len * 2 ) ; step++ ) {
+ /* Calculate byte offset and byte mask */
+ bit_offset = ( ( endianness == SPI_BIT_BIG_ENDIAN ) ?
+ ( len - ( step / 2 ) - 1 ) : ( step / 2 ) );
+ byte_offset = ( bit_offset / 8 );
+ byte_mask = ( 1 << ( bit_offset % 8 ) );
+
+ /* Shift data in or out */
+ if ( sclk == cpha ) {
+ const uint8_t *byte;
+
+ /* Shift data out */
+ if ( data_out ) {
+ byte = ( data_out + byte_offset );
+ bit = ( *byte & byte_mask );
+ DBGCP ( spibit, "SPIBIT %p wrote bit %d\n",
+ spibit, ( bit ? 1 : 0 ) );
+ } else {
+ bit = 0;
+ }
+ write_bit ( basher, SPI_BIT_MOSI, bit );
+ } else {
+ uint8_t *byte;
+
+ /* Shift data in */
+ bit = read_bit ( basher, SPI_BIT_MISO );
+ if ( data_in ) {
+ DBGCP ( spibit, "SPIBIT %p read bit %d\n",
+ spibit, ( bit ? 1 : 0 ) );
+ byte = ( data_in + byte_offset );
+ *byte &= ~byte_mask;
+ *byte |= ( bit & byte_mask );
+ }
+ }
+
+ /* Toggle clock line */
+ spi_bit_delay();
+ sclk ^= 1;
+ write_bit ( basher, SPI_BIT_SCLK, sclk );
+ }
+}
+
+/**
+ * Read/write data via SPI bit-bashing bus
+ *
+ * @v bus SPI bus
+ * @v device SPI device
+ * @v command Command
+ * @v address Address to read/write (<0 for no address)
+ * @v data_out TX data buffer (or NULL)
+ * @v data_in RX data buffer (or NULL)
+ * @v len Length of transfer
+ * @ret rc Return status code
+ */
+static int spi_bit_rw ( struct spi_bus *bus, struct spi_device *device,
+ unsigned int command, int address,
+ const void *data_out, void *data_in, size_t len ) {
+ struct spi_bit_basher *spibit
+ = container_of ( bus, struct spi_bit_basher, bus );
+ uint32_t tmp_command;
+ uint32_t tmp_address;
+ uint32_t tmp_address_detect;
+
+ /* Open bit-bashing interface */
+ open_bit ( &spibit->basher );
+
+ /* Deassert chip select to reset specified slave */
+ spi_bit_set_slave_select ( spibit, device->slave, DESELECT_SLAVE );
+
+ /* Set clock line to idle state */
+ write_bit ( &spibit->basher, SPI_BIT_SCLK,
+ ( bus->mode & SPI_MODE_CPOL ) );
+
+ /* Assert chip select on specified slave */
+ spi_bit_set_slave_select ( spibit, device->slave, SELECT_SLAVE );
+
+ /* Transmit command */
+ assert ( device->command_len <= ( 8 * sizeof ( tmp_command ) ) );
+ tmp_command = cpu_to_le32 ( command );
+ spi_bit_transfer ( spibit, &tmp_command, NULL, device->command_len,
+ SPI_BIT_BIG_ENDIAN );
+
+ /* Transmit address, if present */
+ if ( address >= 0 ) {
+ assert ( device->address_len <= ( 8 * sizeof ( tmp_address )));
+ tmp_address = cpu_to_le32 ( address );
+ if ( device->address_len == SPI_AUTODETECT_ADDRESS_LEN ) {
+ /* Autodetect address length. This relies on
+ * the device responding with a dummy zero
+ * data bit before the first real data bit.
+ */
+ DBGC ( spibit, "SPIBIT %p autodetecting device "
+ "address length\n", spibit );
+ assert ( address == 0 );
+ device->address_len = 0;
+ do {
+ spi_bit_transfer ( spibit, &tmp_address,
+ &tmp_address_detect, 1,
+ SPI_BIT_BIG_ENDIAN );
+ device->address_len++;
+ } while ( le32_to_cpu ( tmp_address_detect ) & 1 );
+ DBGC ( spibit, "SPIBIT %p autodetected device address "
+ "length %d\n", spibit, device->address_len );
+ } else {
+ spi_bit_transfer ( spibit, &tmp_address, NULL,
+ device->address_len,
+ SPI_BIT_BIG_ENDIAN );
+ }
+ }
+
+ /* Transmit/receive data */
+ spi_bit_transfer ( spibit, data_out, data_in, ( len * 8 ),
+ spibit->endianness );
+
+ /* Deassert chip select on specified slave */
+ spi_bit_set_slave_select ( spibit, device->slave, DESELECT_SLAVE );
+
+ /* Close bit-bashing interface */
+ close_bit ( &spibit->basher );
+
+ return 0;
+}
+
+/**
+ * Initialise SPI bit-bashing interface
+ *
+ * @v spibit SPI bit-bashing interface
+ */
+void init_spi_bit_basher ( struct spi_bit_basher *spibit ) {
+ assert ( &spibit->basher.op->read != NULL );
+ assert ( &spibit->basher.op->write != NULL );
+ spibit->bus.rw = spi_bit_rw;
+}
Code Review / kvmfornfv.git / blobdiff