SAM3U: Add logic to bypass automated control of SPI chip selects

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@4032 42af7a65-404d-4744-a932-0658087f49c3

3 files changed, 107 insertions, 15 deletions

diff --git a/nuttx/configs/sam3u-ek/src/sam3uek_internal.h b/nuttx/configs/sam3u-ek/src/sam3uek_internal.h
index 1aa66d517..5b5138960 100644
--- a/nuttx/configs/sam3u-ek/src/sam3uek_internal.h
+++ b/nuttx/configs/sam3u-ek/src/sam3uek_internal.h
@@ -164,9 +164,17 @@
 
 /* SPI Chip Selects */
 
-/* Chip select pin connected to the touchscreen controller and to ZigBee module connector. */
+/* Chip select pin connected to the touchscreen controller and to the ZigBee module
+ * connector.  Notice that the touchscreen chip select is implemented as a GPIO
+ * OUTPUT that must be controlled by board-specific.  This is because the ADS7843E
+ * driver must be able to sample the device BUSY GPIO input between SPI transfers.
+ * However, the AD7843E will tri-state the BUSY input whenever the chip select is
+ * de-asserted.  So the only option is to control the chip select manually and hold
+ * it low throughout the SPI transfer.
+ */
 
-#define GPIO_TSC_NPCS2  GPIO_SPI0_NPCS2_3
+#define GPIO_TSC_NPCS2 (GPIO_OUTPUT|GPIO_CFG_PULLUP|GPIO_OUTPUT_SET|\
+                        GPIO_PORT_PIOC|GPIO_PIN14)
 
 /************************************************************************************
  * Public Types
diff --git a/nuttx/configs/sam3u-ek/src/up_lcd.c b/nuttx/configs/sam3u-ek/src/up_lcd.c
index 2de563f9b..22cbeca88 100644
--- a/nuttx/configs/sam3u-ek/src/up_lcd.c
+++ b/nuttx/configs/sam3u-ek/src/up_lcd.c
@@ -798,9 +798,9 @@ static int sam3u_setpower(struct lcd_dev_s *dev, int power)
       sam3u_gpiowrite(GPIO_LCD_BKL, false);
       sam3u_gpiowrite(GPIO_LCD_BKL, false);
       sam3u_gpiowrite(GPIO_LCD_BKL, false);
-      sam3u_gpiowrite(GPIO_LCD_BKL, true);;
-      sam3u_gpiowrite(GPIO_LCD_BKL, true);;
-      sam3u_gpiowrite(GPIO_LCD_BKL, true);;
+      sam3u_gpiowrite(GPIO_LCD_BKL, true);
+      sam3u_gpiowrite(GPIO_LCD_BKL, true);
+      sam3u_gpiowrite(GPIO_LCD_BKL, true);
     }
 
   /* This delay seems to be required... perhaps because of the big current jump? */
diff --git a/nuttx/configs/sam3u-ek/src/up_spi.c b/nuttx/configs/sam3u-ek/src/up_spi.c
index 515dab2e7..8fed3c48f 100644
--- a/nuttx/configs/sam3u-ek/src/up_spi.c
+++ b/nuttx/configs/sam3u-ek/src/up_spi.c
@@ -107,20 +107,29 @@ void weak_function sam3u_spiinitialize(void)
 }
 
 /****************************************************************************
- * Name:  sam3u_spiselect, sam3u_spistatus, and sam3u_spicmddata
+ * Name:  sam3u_spicsnumber, sam3u_spiselect, sam3u_spistatus, and
+ *        sam3u_spicmddata
  *
  * Description:
  *   These external functions must be provided by board-specific logic.  They
- *   are implementations of the select, status, and cmddata methods of the SPI
- *   interface defined by struct spi_ops_s (see include/nuttx/spi.h). All
- *   other methods including up_spiinitialize()) are provided by common SAM3U
- *   logic.  To use this common SPI logic on your board:
+ *   include:
+ *
+ *   o sam3u_spicsnumbe and sam3u_spiselect which are helper functions to
+ *     manage the board-specific aspects of the unique SAM3U chip select
+ *     architecture.
+ *   o sam3u_spistatus and sam3u_spicmddata:  Implementations of the status
+ *     and cmddata methods of the SPI interface defined by struct spi_ops_
+ *     (see include/nuttx/spi.h). All other methods including
+ *     up_spiinitialize()) are provided by common SAM3U logic.
+ *
+ *  To use this common SPI logic on your board:
  *
  *   1. Provide logic in sam3u_boardinitialize() to configure SPI chip select
  *      pins.
- *   2. Provide sam3u_spiselect() and sam3u_spistatus() functions in your
- *      board-specific logic.  These functions will perform chip selection
- *      and status operations using GPIOs in the way your board is configured.
+ *   2. Provide sam3u_spicsnumber(), sam3u_spiselect() and sam3u_spistatus()
+ *      functions in your board-specific logic.  These functions will perform
+ *      chip selection and status operations using GPIOs in the way your board
+ *      is configured.
  *   2. If CONFIG_SPI_CMDDATA is defined in the NuttX configuration, provide
  *      sam3u_spicmddata() functions in your board-specific logic.  This
  *      function will perform cmd/data selection operations using GPIOs in
@@ -134,8 +143,26 @@ void weak_function sam3u_spiinitialize(void)
  *
  ****************************************************************************/
 
+/****************************************************************************
+ * Name: sam3u_spicsnumber
+ *
+ * Description:
+ *   The SAM3U has 4 CS registers for controlling device features.  This
+ *   function must be provided by board-specific code.  Given a logical device
+ *   ID, this function returns a number from 0 to 3 that identifies one of
+ *   these SAM3U CS resources.
+ *
+ * Input Parameters:
+ *   devid - Identifies the (logical) device
+ *
+ * Returned Values:
+ *   On success, a CS number from 0 to 3 is returned; A negated errno may
+ *   be returned on a failure.
+ *
+ ****************************************************************************/
+
 #ifdef CONFIG_SAM3U_SPI
-int sam3u_spiselect(enum spi_dev_e devid)
+int sam3u_spicsnumber(enum spi_dev_e devid)
 {
   int cs = -EINVAL;
 
@@ -144,7 +171,7 @@ int sam3u_spiselect(enum spi_dev_e devid)
     {
       /* Assert the CS pin to the OLED display */
 
-	  cs = 2;
+      cs = 2;
     }
 #endif
 
@@ -152,6 +179,63 @@ int sam3u_spiselect(enum spi_dev_e devid)
   return cs;
 }
 
+/****************************************************************************
+ * Name: sam3u_spiselect
+ *
+ * Description:
+ *   PIO chip select pins may be programmed by the board specific logic in
+ *   one of two different ways.  First, the pins may be programmed as SPI
+ *   peripherals.  In that case, the pins are completely controlled by the
+ *   SPI driver.  This method still needs to be provided, but it may be only
+ *   a stub.
+ *
+ *   An alternative way to program the PIO chip select pins is as a normal
+ *   GPIO output.  In that case, the automatic control of the CS pins is
+ *   bypassed and this function must provide control of the chip select.
+ *   NOTE:  In this case, the GPIO output pin does *not* have to be the
+ *   same as the NPCS pin normal associated with the chip select number.
+ *
+ * Input Parameters:
+ *   devid - Identifies the (logical) device
+ *   selected - TRUE:Select the device, FALSE:De-select the device
+ *
+ * Returned Values:
+ *   None
+ *
+ ****************************************************************************/
+
+void sam3u_spiselect(enum spi_dev_e devid, bool selected)
+{
+  /* The touchscreen chip select is implemented as a GPIO OUTPUT that must
+   * be controlled by this function.  This is because the ADS7843E driver
+   * must be able to sample the device BUSY GPIO input between SPI transfers.
+   * However, the AD7843E will tri-state the BUSY input whenever the chip
+   * select is de-asserted.  So the only option is to control the chip select
+   * manually and hold it low throughout the SPI transfer.
+   */
+
+#if defined(CONFIG_INPUT) && defined(CONFIG_INPUT_ADS7843E)
+  if (devid == SPIDEV_TOUCHSCREEN)
+    {
+      sam3u_gpiowrite(GPIO_TSC_NPCS2, !selected);
+    }
+#endif
+}
+
+/****************************************************************************
+ * Name: sam3u_spistatus
+ *
+ * Description:
+ *   Return status information associated with the SPI device.
+ *
+ * Input Parameters:
+ *   devid - Identifies the (logical) device
+ *
+ * Returned Values:
+ *   Bit-encoded SPI status (see include/nuttx/spi.h.
+ *
+ ****************************************************************************/
+
 uint8_t sam3u_spistatus(FAR struct spi_dev_s *dev, enum spi_dev_e devid)
 {
   return 0;