Add an optional hwfeatures method to the SPI interface

ChangeLog

@@ -11348,4 +11348,6 @@
 	  buffering and race conditions.  These were necessary for for the
 	  NuttX networking later to be stable in some stress testing.  From
 	  Andrew Webster (2016-01-22).
+	* include/spi/spi.h:  Add an optional hwfeaqtures() method to the
+	  SPI interface (2016-01-22).
 

arch

@@ -1 +1 @@
-Subproject commit eabf13f41e38c104b907bb4cb29655b3cba9f35f
+Subproject commit 10e420a652fd8bcf9441f542172182f5db05e70a

configs

@@ -1 +1 @@
-Subproject commit bc84da30695b62f2d559ce49993b72489d605480
+Subproject commit 5f36fcd26edfb955c28974a2d335ad5e82a3c515

drivers/spi/Kconfig

@@ -62,6 +62,23 @@ config SPI_BITBANG
 		Enable support for a generic SPI bit-bang device.
 		See include/nuttx/spi/spi_bitbang.h for further information.
 
+config SPI_HWFEATURES
+	bool
+	default n
+	---help---
+		Selected only if a specific H/W feature is selected.  This is
+		basically the OR of any specific hardware feature and eanbles
+		the SPI hwfeatures() interface method.
+
+config SPI_CRCGENERATION
+	bool
+	default n
+	select SPI_HWFEATURES
+	---help---
+		Selected by MCU Kconfig logic if implementation supports automatic
+		generation of SPI CRCs.  Enables the HWFEAT_CRCGENERATION option
+		as well as the hwfeartures() interface method.
+
 if SPI_BITBANG
 
 config SPI_BITBANG_VARWIDTH

drivers/spi/spi_bitbang.c

@@ -1,7 +1,7 @@
 /****************************************************************************
  * drivers/spi/spi_bitbang.c
  *
- *   Copyright (C) 2013 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2013, 2016 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -145,24 +145,27 @@ static int      spi_cmddata(FAR struct spi_dev_s *dev, enum spi_dev_e devid,
 static const struct spi_ops_s g_spiops =
 {
 #ifndef CONFIG_SPI_OWNBUS
-  .lock              = spi_lock,
+  spi_lock,           /* lock */
 #endif
-  .select            = spi_select,
-  .setfrequency      = spi_setfrequency,
-  .setmode           = spi_setmode,
-  .setbits           = spi_setbits,
-  .status            = spi_status,
+  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
-  .cmddata           = spi_cmddata,
+  spi_cmddata,        /* cmddata */
 #endif
-  .send              = spi_send,
+  spi_send,           /* send */
 #ifdef CONFIG_SPI_EXCHANGE
-  .exchange          = spi_exchange,
+  spi_exchange,       /* exchange */
 #else
-  .sndblock          = spi_sndblock,
-  .recvblock         = spi_recvblock,
+  spi_sndblock,       /* sndblock */
+  spi_recvblock,      /* recvblock */
 #endif
-  .registercallback  = 0,                 /* Not implemented */
+   0                  /* registercallback */
 };
 
 /****************************************************************************

include/nuttx/spi/spi.h

@@ -1,7 +1,7 @@
 /****************************************************************************
  * include/nuttx/spi/spi.h
  *
- *   Copyright(C) 2008-2013, 2015 Gregory Nutt. All rights reserved.
+ *   Copyright(C) 2008-2013, 2015-2016 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -45,6 +45,7 @@
 #include <sys/types.h>
 #include <stdint.h>
 #include <stdbool.h>
+#include <assert.h>
 
 /****************************************************************************
  * Pre-processor Definitions
@@ -166,6 +167,44 @@
 #define SPI_SETBITS(d,b) \
   do { if ((d)->ops->setbits) (d)->ops->setbits(d,b); } while (0)
 
+/****************************************************************************
+ * Name: SPI_HWFEATURES
+ *
+ * Description:
+ *   Set hardware-specific feature flags.
+ *
+ * Input Parameters:
+ *   dev   - Device-specific state data
+ *   flags - H/W feature flags
+ *
+ * Returned Value:
+ *   Zero (OK) if the selected H/W features are enabled; A negated errno
+ *   value if any H/W feature is not supportable.
+ *
+ ****************************************************************************/
+
+#ifdef CONFIG_SPI_HWFEATURES
+  /* If there are multiple SPI drivers, some may not support hardware
+   * feature selection.
+   */
+
+#  define SPI_HWFEATURES(d,f) \
+  (((d)->ops->hwfeatures) ? (d)->ops->hwfeatures(d,f) : ((f) == 0 ? OK : -ENOSYS))
+
+  /* These are currently defined feature flags */
+
+#  ifdef CONFIG_SPI_CRCGENERATION
+#    HWFEAT_CRCGENERATION (1 << 0) /* Bit 0: Hardward CRC generation */
+#  endif
+
+#else
+  /* Any attempt to select hardware features with CONFIG_SPI_HWFEATURES
+   * deselected will cause an assertion.
+   */
+
+#  define SPI_HWFEATURES(d,f) (((f) == 0) ? OK : -ENOSYS)
+#endif
+
 /****************************************************************************
  * Name: SPI_STATUS
  *
@@ -378,6 +417,12 @@ enum spi_mode_e
   SPIDEV_MODE3          /* CPOL=1 CHPHA=1 */
 };
 
+#ifdef CONFIG_SPI_HWFEATURES
+/* This is a type wide enough to support all hardware features */
+
+typedef uint8_t spi_hwfeatures_t;
+#endif
+
 /* The SPI vtable */
 
 struct spi_dev_s;
@@ -391,6 +436,10 @@ struct spi_ops_s
   CODE uint32_t (*setfrequency)(FAR struct spi_dev_s *dev, uint32_t frequency);
   CODE void     (*setmode)(FAR struct spi_dev_s *dev, enum spi_mode_e mode);
   CODE void     (*setbits)(FAR struct spi_dev_s *dev, int nbits);
+#ifdef CONFIG_SPI_HWFEATURES
+  CODE int      (*hwfeatures)(FAR struct spi_dev_s *dev,
+                  spi_hwfeatures_t features);
+#endif
   CODE uint8_t  (*status)(FAR struct spi_dev_s *dev, enum spi_dev_e devid);
 #ifdef CONFIG_SPI_CMDDATA
   CODE int      (*cmddata)(FAR struct spi_dev_s *dev, enum spi_dev_e devid,