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authorwdenk <wdenk>2002-10-01 01:07:28 +0000
committerwdenk <wdenk>2002-10-01 01:07:28 +0000
commite3093091a9d0e7a0709ee79390414b5a5ca69f88 (patch)
treecbe85919e2bbf5937893fdcdfc88343380e694c5 /common/soft_spi.c
parenta2cecab6df0cfc6206ed3de29abe5d17cd4017a0 (diff)
Initial revision
Diffstat (limited to 'common/soft_spi.c')
-rw-r--r--common/soft_spi.c138
1 files changed, 138 insertions, 0 deletions
diff --git a/common/soft_spi.c b/common/soft_spi.c
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+/*
+ * (C) Copyright 2002
+ * Gerald Van Baren, Custom IDEAS, vanbaren@cideas.com.
+ *
+ * Influenced by code from:
+ * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
+ *
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * 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 (at your option) 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., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+#include <common.h>
+#include <spi.h>
+
+#if defined(CONFIG_SOFT_SPI)
+
+#define DEBUG_SPI
+
+
+/*-----------------------------------------------------------------------
+ * Definitions
+ */
+
+#ifdef DEBUG_SPI
+#define PRINTD(fmt,args...) printf (fmt ,##args)
+#else
+#define PRINTD(fmt,args...)
+#endif
+
+
+
+/*=====================================================================*/
+/* Public Functions */
+/*=====================================================================*/
+
+/*-----------------------------------------------------------------------
+ * Initialization
+ */
+void spi_init (void)
+{
+#ifdef SPI_INIT
+ volatile immap_t *immr = (immap_t *)CFG_IMMR;
+
+ SPI_INIT;
+#endif
+}
+
+
+/*-----------------------------------------------------------------------
+ * SPI transfer
+ *
+ * This writes "bitlen" bits out the SPI MOSI port and simultaneously clocks
+ * "bitlen" bits in the SPI MISO port. That's just the way SPI works.
+ *
+ * The source of the outgoing bits is the "dout" parameter and the
+ * destination of the input bits is the "din" parameter. Note that "dout"
+ * and "din" can point to the same memory location, in which case the
+ * input data overwrites the output data (since both are buffered by
+ * temporary variables, this is OK).
+ *
+ * If the chipsel() function is not NULL, it is called with a parameter
+ * of '1' (chip select active) at the start of the transfer and again with
+ * a parameter of '0' at the end of the transfer.
+ *
+ * If the chipsel() function _is_ NULL, it the responsibility of the
+ * caller to make the appropriate chip select active before calling
+ * spi_xfer() and making it inactive after spi_xfer() returns.
+ */
+int spi_xfer(spi_chipsel_type chipsel, int bitlen, uchar *dout, uchar *din)
+{
+ volatile immap_t *immr = (immap_t *)CFG_IMMR;
+ uchar tmpdin = 0;
+ uchar tmpdout = 0;
+ int j;
+
+ PRINTD("spi_xfer: chipsel %08X dout %08X din %08X bitlen %d\n",
+ (int)chipsel, *(uint *)dout, *(uint *)din, bitlen);
+
+ if(chipsel != NULL) {
+ (*chipsel)(1); /* select the target chip */
+ }
+
+ for(j = 0; j < bitlen; j++) {
+ /*
+ * Check if it is time to work on a new byte.
+ */
+ if((j % 8) == 0) {
+ tmpdout = *dout++;
+ if(j != 0) {
+ *din++ = tmpdin;
+ }
+ tmpdin = 0;
+ }
+ SPI_SCL(0);
+ SPI_SDA(tmpdout & 0x80);
+ SPI_DELAY;
+ SPI_SCL(1);
+ SPI_DELAY;
+ tmpdin <<= 1;
+ tmpdin |= SPI_READ;
+ tmpdout <<= 1;
+ }
+ /*
+ * If the number of bits isn't a multiple of 8, shift the last
+ * bits over to left-justify them. Then store the last byte
+ * read in.
+ */
+ if((bitlen % 8) != 0)
+ tmpdin <<= 8 - (bitlen % 8);
+ *din++ = tmpdin;
+
+ SPI_SCL(0); /* SPI wants the clock left low for idle */
+
+ if(chipsel != NULL) {
+ (*chipsel)(0); /* deselect the target chip */
+
+ }
+
+ return(0);
+}
+
+#endif /* CONFIG_SOFT_SPI */
+