staging: comedi: add new device-global config interface

Adds interface for configuring options that are global to all sub-devices.
For now, only options to configure device-globally identified signal routes
have been defined.
Signed-off-by: Spencer E. Olson <olsonse@umich.edu>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/comedi.h

@@ -107,6 +107,7 @@
 #define INSN_WRITE		(1 | INSN_MASK_WRITE)
 #define INSN_BITS		(2 | INSN_MASK_READ | INSN_MASK_WRITE)
 #define INSN_CONFIG		(3 | INSN_MASK_READ | INSN_MASK_WRITE)
+#define INSN_DEVICE_CONFIG	(INSN_CONFIG | INSN_MASK_SPECIAL)
 #define INSN_GTOD		(4 | INSN_MASK_READ | INSN_MASK_SPECIAL)
 #define INSN_WAIT		(5 | INSN_MASK_WRITE | INSN_MASK_SPECIAL)
 #define INSN_INTTRIG		(6 | INSN_MASK_WRITE | INSN_MASK_SPECIAL)
@@ -350,6 +351,23 @@ enum configuration_ids {
 	INSN_CONFIG_GET_CMD_TIMING_CONSTRAINTS = 5005,
 };
 
+/**
+ * enum device_configuration_ids - COMEDI configuration instruction codes global
+ * to an entire device.
+ * @INSN_DEVICE_CONFIG_TEST_ROUTE:	Validate the possibility of a
+ *					globally-named route
+ * @INSN_DEVICE_CONFIG_CONNECT_ROUTE:	Connect a globally-named route
+ * @INSN_DEVICE_CONFIG_DISCONNECT_ROUTE:Disconnect a globally-named route
+ * @INSN_DEVICE_CONFIG_GET_ROUTES:	Get a list of all globally-named routes
+ *					that are valid for a particular device.
+ */
+enum device_config_route_ids {
+	INSN_DEVICE_CONFIG_TEST_ROUTE = 0,
+	INSN_DEVICE_CONFIG_CONNECT_ROUTE = 1,
+	INSN_DEVICE_CONFIG_DISCONNECT_ROUTE = 2,
+	INSN_DEVICE_CONFIG_GET_ROUTES = 3,
+};
+
 /**
  * enum comedi_digital_trig_op - operations for configuring a digital trigger
  * @COMEDI_DIGITAL_TRIG_DISABLE:	Return digital trigger to its default,

drivers/staging/comedi/comedi_fops.c

@@ -1234,6 +1234,57 @@ static int check_insn_config_length(struct comedi_insn *insn,
 	return -EINVAL;
 }
 
+static int check_insn_device_config_length(struct comedi_insn *insn,
+					   unsigned int *data)
+{
+	if (insn->n < 1)
+		return -EINVAL;
+
+	switch (data[0]) {
+	case INSN_DEVICE_CONFIG_TEST_ROUTE:
+	case INSN_DEVICE_CONFIG_CONNECT_ROUTE:
+	case INSN_DEVICE_CONFIG_DISCONNECT_ROUTE:
+		if (insn->n == 3)
+			return 0;
+		break;
+	case INSN_DEVICE_CONFIG_GET_ROUTES:
+		/*
+		 * Big enough for config_id and the length of the userland
+		 * memory buffer.  Additional length should be in factors of 2
+		 * to communicate any returned route pairs (source,destination).
+		 */
+		if (insn->n >= 2)
+			return 0;
+		break;
+	}
+	return -EINVAL;
+}
+
+/**
+ * get_valid_routes() - Calls low-level driver get_valid_routes function to
+ *			either return a count of valid routes to user, or copy
+ *			of list of all valid device routes to buffer in
+ *			userspace.
+ * @dev: comedi device pointer
+ * @data: data from user insn call.  The length of the data must be >= 2.
+ *	  data[0] must contain the INSN_DEVICE_CONFIG config_id.
+ *	  data[1](input) contains the number of _pairs_ for which memory is
+ *		  allotted from the user.  If the user specifies '0', then only
+ *		  the number of pairs available is returned.
+ *	  data[1](output) returns either the number of pairs available (if none
+ *		  where requested) or the number of _pairs_ that are copied back
+ *		  to the user.
+ *	  data[2::2] returns each (source, destination) pair.
+ *
+ * Return: -EINVAL if low-level driver does not allocate and return routes as
+ *	   expected.  Returns 0 otherwise.
+ */
+static int get_valid_routes(struct comedi_device *dev, unsigned int *data)
+{
+	data[1] = dev->get_valid_routes(dev, data[1], data + 2);
+	return 0;
+}
+
 static int parse_insn(struct comedi_device *dev, struct comedi_insn *insn,
 		      unsigned int *data, void *file)
 {
@@ -1297,6 +1348,24 @@ static int parse_insn(struct comedi_device *dev, struct comedi_insn *insn,
 			if (ret >= 0)
 				ret = 1;
 			break;
+		case INSN_DEVICE_CONFIG:
+			ret = check_insn_device_config_length(insn, data);
+			if (ret)
+				break;
+
+			if (data[0] == INSN_DEVICE_CONFIG_GET_ROUTES) {
+				/*
+				 * data[1] should be the number of _pairs_ that
+				 * the memory can hold.
+				 */
+				data[1] = (insn->n - 2) / 2;
+				ret = get_valid_routes(dev, data);
+				break;
+			}
+
+			/* other global device config instructions. */
+			ret = dev->insn_device_config(dev, insn, data);
+			break;
 		default:
 			dev_dbg(dev->class_dev, "invalid insn\n");
 			ret = -EINVAL;

drivers/staging/comedi/comedidev.h

@@ -516,6 +516,15 @@ struct comedi_driver {
  *	called when @use_count changes from 0 to 1.
  * @close: Optional pointer to a function set by the low-level driver to be
  *	called when @use_count changed from 1 to 0.
+ * @insn_device_config: Optional pointer to a handler for all sub-instructions
+ *	except %INSN_DEVICE_CONFIG_GET_ROUTES of the %INSN_DEVICE_CONFIG
+ *	instruction.  If this is not initialized by the low-level driver, a
+ *	default handler will be set during post-configuration.
+ * @get_valid_routes: Optional pointer to a handler for the
+ *	%INSN_DEVICE_CONFIG_GET_ROUTES sub-instruction of the
+ *	%INSN_DEVICE_CONFIG instruction set.  If this is not initialized by the
+ *	low-level driver, a default handler that copies zero routes back to the
+ *	user will be used.
  *
  * This is the main control data structure for a COMEDI device (as far as the
  * COMEDI core is concerned).  There are two groups of COMEDI devices -
@@ -565,6 +574,11 @@ struct comedi_device {
 
 	int (*open)(struct comedi_device *dev);
 	void (*close)(struct comedi_device *dev);
+	int (*insn_device_config)(struct comedi_device *dev,
+				  struct comedi_insn *insn, unsigned int *data);
+	unsigned int (*get_valid_routes)(struct comedi_device *dev,
+					 unsigned int n_pairs,
+					 unsigned int *pair_data);
 };
 
 /*

drivers/staging/comedi/drivers.c

@@ -211,6 +211,19 @@ static int poll_invalid(struct comedi_device *dev, struct comedi_subdevice *s)
 	return -EINVAL;
 }
 
+static int insn_device_inval(struct comedi_device *dev,
+			     struct comedi_insn *insn, unsigned int *data)
+{
+	return -EINVAL;
+}
+
+static unsigned int get_zero_valid_routes(struct comedi_device *dev,
+					  unsigned int n_pairs,
+					  unsigned int *pair_data)
+{
+	return 0;
+}
+
 int insn_inval(struct comedi_device *dev, struct comedi_subdevice *s,
 	       struct comedi_insn *insn, unsigned int *data)
 {
@@ -652,6 +665,12 @@ static int __comedi_device_postconfig(struct comedi_device *dev)
 	int ret;
 	int i;
 
+	if (!dev->insn_device_config)
+		dev->insn_device_config = insn_device_inval;
+
+	if (!dev->get_valid_routes)
+		dev->get_valid_routes = get_zero_valid_routes;
+
 	for (i = 0; i < dev->n_subdevices; i++) {
 		s = &dev->subdevices[i];