altos: Split out SPI driver.

[fw/altos] / src / ao_spi.c

diff --git a/src/ao_spi.c b/src/ao_spi.c
new file mode 100644 (file)
index 0000000..bd52a0d
--- /dev/null
+++ b/src/ao_spi.c
@@ -0,0 +1,157 @@
+/*
+ * Copyright © 2010 Keith Packard <keithp@keithp.com>
+ *
+ * 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; version 2 of the License.
+ *
+ * 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 "ao.h"
+
+__xdata uint8_t        ao_spi_mutex;
+__xdata uint8_t ao_spi_dma_in_done;
+__xdata uint8_t ao_spi_dma_out_done;
+
+uint8_t        ao_spi_dma_out_id;
+uint8_t ao_spi_dma_in_id;
+
+static __xdata uint8_t ao_spi_const = 0xff;
+
+/* Send bytes over SPI.
+ *
+ * This sets up two DMA engines, one writing the data and another reading
+ * bytes coming back.  We use the bytes coming back to tell when the transfer
+ * is complete, as the transmit register is double buffered and hence signals
+ * completion one byte before the transfer is actually complete
+ */
+void
+ao_spi_send(void __xdata *block, uint16_t len) __reentrant
+{
+       ao_mutex_get(&ao_spi_mutex);
+       ao_dma_set_transfer(ao_spi_dma_in_id,
+                           &U0DBUFXADDR,
+                           &ao_spi_const,
+                           len,
+                           DMA_CFG0_WORDSIZE_8 |
+                           DMA_CFG0_TMODE_SINGLE |
+                           DMA_CFG0_TRIGGER_URX0,
+                           DMA_CFG1_SRCINC_0 |
+                           DMA_CFG1_DESTINC_0 |
+                           DMA_CFG1_PRIORITY_NORMAL);
+
+       ao_dma_set_transfer(ao_spi_dma_out_id,
+                           block,
+                           &U0DBUFXADDR,
+                           len,
+                           DMA_CFG0_WORDSIZE_8 |
+                           DMA_CFG0_TMODE_SINGLE |
+                           DMA_CFG0_TRIGGER_UTX0,
+                           DMA_CFG1_SRCINC_1 |
+                           DMA_CFG1_DESTINC_0 |
+                           DMA_CFG1_PRIORITY_NORMAL);
+
+       ao_dma_start(ao_spi_dma_in_id);
+       ao_dma_start(ao_spi_dma_out_id);
+       ao_dma_trigger(ao_spi_dma_out_id);
+       __critical while (!ao_spi_dma_in_done)
+               ao_sleep(&ao_spi_dma_in_done);
+       ao_mutex_put(&ao_spi_mutex);
+}
+
+/* Receive bytes over SPI.
+ *
+ * This sets up tow DMA engines, one reading the data and another
+ * writing constant values to the SPI transmitter as that is what
+ * clocks the data coming in.
+ */
+void
+ao_spi_recv(void __xdata *block, uint16_t len) __reentrant
+{
+       ao_mutex_get(&ao_spi_mutex);
+       ao_dma_set_transfer(ao_spi_dma_in_id,
+                           &U0DBUFXADDR,
+                           block,
+                           len,
+                           DMA_CFG0_WORDSIZE_8 |
+                           DMA_CFG0_TMODE_SINGLE |
+                           DMA_CFG0_TRIGGER_URX0,
+                           DMA_CFG1_SRCINC_0 |
+                           DMA_CFG1_DESTINC_1 |
+                           DMA_CFG1_PRIORITY_NORMAL);
+
+       ao_dma_set_transfer(ao_spi_dma_out_id,
+                           &ao_spi_const,
+                           &U0DBUFXADDR,
+                           len,
+                           DMA_CFG0_WORDSIZE_8 |
+                           DMA_CFG0_TMODE_SINGLE |
+                           DMA_CFG0_TRIGGER_UTX0,
+                           DMA_CFG1_SRCINC_0 |
+                           DMA_CFG1_DESTINC_0 |
+                           DMA_CFG1_PRIORITY_NORMAL);
+
+       ao_dma_start(ao_spi_dma_in_id);
+       ao_dma_start(ao_spi_dma_out_id);
+       ao_dma_trigger(ao_spi_dma_out_id);
+       __critical while (!ao_spi_dma_in_done)
+               ao_sleep(&ao_spi_dma_in_done);
+       ao_mutex_put(&ao_spi_mutex);
+}
+
+/*
+ * Initialize USART0 for SPI using config alt 2
+ *
+ *     MO      P1_5
+ *     MI      P1_4
+ *     CLK     P1_3
+ *
+ * Chip select is the responsibility of the caller
+ */
+
+void
+ao_spi_init(void)
+{
+       /* Set up the USART pin assignment */
+       PERCFG = (PERCFG & ~PERCFG_U0CFG_ALT_MASK) | PERCFG_U0CFG_ALT_2;
+
+       /* Ensure that USART0 takes precidence over USART1 for pins that
+        * they share
+        */
+       P2SEL = (P2SEL & ~P2SEL_PRI3P1_MASK) | P2SEL_PRI3P1_USART0;
+
+       /* Make the SPI pins be controlled by the USART peripheral */
+       P1SEL |= ((1 << 5) | (1 << 4) | (1 << 3));
+
+       /* Set up OUT DMA */
+       ao_spi_dma_out_id = ao_dma_alloc(&ao_spi_dma_out_done);
+
+       /* Set up IN DMA */
+       ao_spi_dma_in_id = ao_dma_alloc(&ao_spi_dma_in_done);
+
+       /* Set up the USART.
+        *
+        * SPI master mode
+        */
+       U0CSR = (UxCSR_MODE_SPI | UxCSR_RE | UxCSR_MASTER);
+
+       /* Set the baud rate and signal parameters
+        *
+        * The cc1111 is limited to a 24/8 MHz SPI clock.
+        * Every peripheral I've ever seen goes faster than that,
+        * so set the clock to 3MHz (BAUD_E 17, BAUD_M 0)
+        */
+       U0BAUD = 0;
+       U0GCR = (UxGCR_CPOL_NEGATIVE |
+                UxGCR_CPHA_FIRST_EDGE |
+                UxGCR_ORDER_MSB |
+                (17 << UxGCR_BAUD_E_SHIFT));
+}