spi: Support selection of the index of the ACPI Spi Resource before alloc

If a node contains more than one SPI resource it may be necessary to
use an index to select which one you want to allocate a spi device for.
Signed-off-by: Stefan Binding <sbinding@opensource.cirrus.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20220121172431.6876-4-sbinding@opensource.cirrus.comSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi.c

@@ -2320,6 +2320,8 @@ struct acpi_spi_lookup {
 	int			irq;
 	u8			bits_per_word;
 	u8			chip_select;
+	int			n;
+	int			index;
 };
 
 static void acpi_spi_parse_apple_properties(struct acpi_device *dev,
@@ -2351,6 +2353,8 @@ static void acpi_spi_parse_apple_properties(struct acpi_device *dev,
 		lookup->mode |= SPI_CPHA;
 }
 
+static struct spi_controller *acpi_spi_find_controller_by_adev(struct acpi_device *adev);
+
 static int acpi_spi_add_resource(struct acpi_resource *ares, void *data)
 {
 	struct acpi_spi_lookup *lookup = data;
@@ -2364,14 +2368,35 @@ static int acpi_spi_add_resource(struct acpi_resource *ares, void *data)
 		sb = &ares->data.spi_serial_bus;
 		if (sb->type == ACPI_RESOURCE_SERIAL_TYPE_SPI) {
 
+			if (lookup->index != -1 && lookup->n++ != lookup->index)
+				return 1;
+
+			if (lookup->index == -1 && !ctlr)
+				return -ENODEV;
+
 			status = acpi_get_handle(NULL,
 						 sb->resource_source.string_ptr,
 						 &parent_handle);
 
-			if (ACPI_FAILURE(status) ||
-			    ACPI_HANDLE(ctlr->dev.parent) != parent_handle)
+			if (ACPI_FAILURE(status))
 				return -ENODEV;
 
+			if (ctlr) {
+				if (ACPI_HANDLE(ctlr->dev.parent) != parent_handle)
+					return -ENODEV;
+			} else {
+				struct acpi_device *adev;
+
+				if (acpi_bus_get_device(parent_handle, &adev))
+					return -ENODEV;
+
+				ctlr = acpi_spi_find_controller_by_adev(adev);
+				if (!ctlr)
+					return -ENODEV;
+
+				lookup->ctlr = ctlr;
+			}
+
 			/*
 			 * ACPI DeviceSelection numbering is handled by the
 			 * host controller driver in Windows and can vary
@@ -2414,14 +2439,21 @@ static int acpi_spi_add_resource(struct acpi_resource *ares, void *data)
  * acpi_spi_device_alloc - Allocate a spi device, and fill it in with ACPI information
  * @ctlr: controller to which the spi device belongs
  * @adev: ACPI Device for the spi device
+ * @index: Index of the spi resource inside the ACPI Node
  *
  * This should be used to allocate a new spi device from and ACPI Node.
  * The caller is responsible for calling spi_add_device to register the spi device.
  *
+ * If ctlr is set to NULL, the Controller for the spi device will be looked up
+ * using the resource.
+ * If index is set to -1, index is not used.
+ * Note: If index is -1, ctlr must be set.
+ *
  * Return: a pointer to the new device, or ERR_PTR on error.
  */
 struct spi_device *acpi_spi_device_alloc(struct spi_controller *ctlr,
-					 struct acpi_device *adev)
+					 struct acpi_device *adev,
+					 int index)
 {
 	acpi_handle parent_handle = NULL;
 	struct list_head resource_list;
@@ -2429,8 +2461,13 @@ struct spi_device *acpi_spi_device_alloc(struct spi_controller *ctlr,
 	struct spi_device *spi;
 	int ret;
 
+	if (!ctlr && index == -1)
+		return ERR_PTR(-EINVAL);
+
 	lookup.ctlr		= ctlr;
 	lookup.irq		= -1;
+	lookup.index		= index;
+	lookup.n		= 0;
 
 	INIT_LIST_HEAD(&resource_list);
 	ret = acpi_dev_get_resources(adev, &resource_list,
@@ -2443,7 +2480,7 @@ struct spi_device *acpi_spi_device_alloc(struct spi_controller *ctlr,
 
 	if (!lookup.max_speed_hz &&
 	    ACPI_SUCCESS(acpi_get_parent(adev->handle, &parent_handle)) &&
-	    ACPI_HANDLE(ctlr->dev.parent) == parent_handle) {
+	    ACPI_HANDLE(lookup.ctlr->dev.parent) == parent_handle) {
 		/* Apple does not use _CRS but nested devices for SPI slaves */
 		acpi_spi_parse_apple_properties(adev, &lookup);
 	}
@@ -2451,9 +2488,9 @@ struct spi_device *acpi_spi_device_alloc(struct spi_controller *ctlr,
 	if (!lookup.max_speed_hz)
 		return ERR_PTR(-ENODEV);
 
-	spi = spi_alloc_device(ctlr);
+	spi = spi_alloc_device(lookup.ctlr);
 	if (!spi) {
-		dev_err(&ctlr->dev, "failed to allocate SPI device for %s\n",
+		dev_err(&lookup.ctlr->dev, "failed to allocate SPI device for %s\n",
 			dev_name(&adev->dev));
 		return ERR_PTR(-ENOMEM);
 	}
@@ -2478,7 +2515,7 @@ static acpi_status acpi_register_spi_device(struct spi_controller *ctlr,
 	    acpi_device_enumerated(adev))
 		return AE_OK;
 
-	spi = acpi_spi_device_alloc(ctlr, adev);
+	spi = acpi_spi_device_alloc(ctlr, adev, -1);
 	if (IS_ERR(spi)) {
 		if (PTR_ERR(spi) == -ENOMEM)
 			return AE_NO_MEMORY;

include/linux/spi/spi.h

@@ -762,7 +762,8 @@ extern void spi_unregister_controller(struct spi_controller *ctlr);
 
 #if IS_ENABLED(CONFIG_ACPI)
 extern struct spi_device *acpi_spi_device_alloc(struct spi_controller *ctlr,
-						struct acpi_device *adev);
+						struct acpi_device *adev,
+						int index);
 #endif
 
 /*