spi: Enhance and export helpers for ACPI resources

Merge series from Stefan Binding <sbinding@opensource.cirrus.com>:

This series enhances the helpers for ACPI resources to cope with
multiple resources and exports them for use in the x86 platform code's
multi-instantiate driver.

drivers/spi/spi.c

@@ -532,7 +532,7 @@ static DEFINE_MUTEX(board_lock);
  *
  * Return: a pointer to the new device, or NULL.
  */
-static struct spi_device *spi_alloc_device(struct spi_controller *ctlr)
+struct spi_device *spi_alloc_device(struct spi_controller *ctlr)
 {
 	struct spi_device	*spi;
 
@@ -557,6 +557,7 @@ static struct spi_device *spi_alloc_device(struct spi_controller *ctlr)
 	device_initialize(&spi->dev);
 	return spi;
 }
+EXPORT_SYMBOL_GPL(spi_alloc_device);
 
 static void spi_dev_set_name(struct spi_device *spi)
 {
@@ -652,7 +653,7 @@ static int __spi_add_device(struct spi_device *spi)
  *
  * Return: 0 on success; negative errno on failure
  */
-static int spi_add_device(struct spi_device *spi)
+int spi_add_device(struct spi_device *spi)
 {
 	struct spi_controller *ctlr = spi->controller;
 	struct device *dev = ctlr->dev.parent;
@@ -673,6 +674,7 @@ static int spi_add_device(struct spi_device *spi)
 	mutex_unlock(&ctlr->add_lock);
 	return status;
 }
+EXPORT_SYMBOL_GPL(spi_add_device);
 
 static int spi_add_device_locked(struct spi_device *spi)
 {
@@ -2318,8 +2320,50 @@ struct acpi_spi_lookup {
 	int			irq;
 	u8			bits_per_word;
 	u8			chip_select;
+	int			n;
+	int			index;
 };
 
+static int acpi_spi_count(struct acpi_resource *ares, void *data)
+{
+	struct acpi_resource_spi_serialbus *sb;
+	int *count = data;
+
+	if (ares->type != ACPI_RESOURCE_TYPE_SERIAL_BUS)
+		return 1;
+
+	sb = &ares->data.spi_serial_bus;
+	if (sb->type != ACPI_RESOURCE_SERIAL_TYPE_SPI)
+		return 1;
+
+	*count = *count + 1;
+
+	return 1;
+}
+
+/**
+ * acpi_spi_count_resources - Count the number of SpiSerialBus resources
+ * @adev:	ACPI device
+ *
+ * Returns the number of SpiSerialBus resources in the ACPI-device's
+ * resource-list; or a negative error code.
+ */
+int acpi_spi_count_resources(struct acpi_device *adev)
+{
+	LIST_HEAD(r);
+	int count = 0;
+	int ret;
+
+	ret = acpi_dev_get_resources(adev, &r, acpi_spi_count, &count);
+	if (ret < 0)
+		return ret;
+
+	acpi_dev_free_resource_list(&r);
+
+	return count;
+}
+EXPORT_SYMBOL_GPL(acpi_spi_count_resources);
+
 static void acpi_spi_parse_apple_properties(struct acpi_device *dev,
 					    struct acpi_spi_lookup *lookup)
 {
@@ -2349,6 +2393,8 @@ 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;
@@ -2362,14 +2408,35 @@ 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
@@ -2408,8 +2475,25 @@ static int acpi_spi_add_resource(struct acpi_resource *ares, void *data)
 	return 1;
 }
 
-static acpi_status acpi_register_spi_device(struct spi_controller *ctlr,
-					    struct acpi_device *adev)
+/**
+ * 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,
+					 int index)
 {
 	acpi_handle parent_handle = NULL;
 	struct list_head resource_list;
@@ -2417,12 +2501,13 @@ static acpi_status acpi_register_spi_device(struct spi_controller *ctlr,
 	struct spi_device *spi;
 	int ret;
 
-	if (acpi_bus_get_status(adev) || !adev->status.present ||
-	    acpi_device_enumerated(adev))
-		return AE_OK;
+	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,
@@ -2431,26 +2516,25 @@ static acpi_status acpi_register_spi_device(struct spi_controller *ctlr,
 
 	if (ret < 0)
 		/* found SPI in _CRS but it points to another controller */
-		return AE_OK;
+		return ERR_PTR(-ENODEV);
 
 	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);
 	}
 
 	if (!lookup.max_speed_hz)
-		return AE_OK;
+		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 AE_NO_MEMORY;
+		return ERR_PTR(-ENOMEM);
 	}
 
-
 	ACPI_COMPANION_SET(&spi->dev, adev);
 	spi->max_speed_hz	= lookup.max_speed_hz;
 	spi->mode		|= lookup.mode;
@@ -2458,6 +2542,27 @@ static acpi_status acpi_register_spi_device(struct spi_controller *ctlr,
 	spi->bits_per_word	= lookup.bits_per_word;
 	spi->chip_select	= lookup.chip_select;
 
+	return spi;
+}
+EXPORT_SYMBOL_GPL(acpi_spi_device_alloc);
+
+static acpi_status acpi_register_spi_device(struct spi_controller *ctlr,
+					    struct acpi_device *adev)
+{
+	struct spi_device *spi;
+
+	if (acpi_bus_get_status(adev) || !adev->status.present ||
+	    acpi_device_enumerated(adev))
+		return AE_OK;
+
+	spi = acpi_spi_device_alloc(ctlr, adev, -1);
+	if (IS_ERR(spi)) {
+		if (PTR_ERR(spi) == -ENOMEM)
+			return AE_NO_MEMORY;
+		else
+			return AE_OK;
+	}
+
 	acpi_set_modalias(adev, acpi_device_hid(adev), spi->modalias,
 			  sizeof(spi->modalias));
 

include/linux/spi/spi.h

@@ -16,6 +16,7 @@
 #include <linux/gpio/consumer.h>
 
 #include <uapi/linux/spi/spi.h>
+#include <linux/acpi.h>
 
 struct dma_chan;
 struct software_node;
@@ -759,6 +760,13 @@ extern int devm_spi_register_controller(struct device *dev,
 					struct spi_controller *ctlr);
 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,
+						int index);
+int acpi_spi_count_resources(struct acpi_device *adev);
+#endif
+
 /*
  * SPI resource management while processing a SPI message
  */
@@ -1452,7 +1460,19 @@ spi_register_board_info(struct spi_board_info const *info, unsigned n)
  * use spi_new_device() to describe each device.  You can also call
  * spi_unregister_device() to start making that device vanish, but
  * normally that would be handled by spi_unregister_controller().
+ *
+ * You can also use spi_alloc_device() and spi_add_device() to use a two
+ * stage registration sequence for each spi_device. This gives the caller
+ * some more control over the spi_device structure before it is registered,
+ * but requires that caller to initialize fields that would otherwise
+ * be defined using the board info.
  */
+extern struct spi_device *
+spi_alloc_device(struct spi_controller *ctlr);
+
+extern int
+spi_add_device(struct spi_device *spi);
+
 extern struct spi_device *
 spi_new_device(struct spi_controller *, struct spi_board_info *);