[PATCH v2 2/3] spi / ACPI: add ACPI enumeration support

[Mika Westerberg]

ACPI 5 introduced SPISerialBus resource that allows us to enumerate and
configure the SPI slave devices behind the SPI controller. This patch adds
support for this to the SPI core.

In addition we bind ACPI nodes to SPI devices. This makes it possible for
the slave drivers to get the ACPI handle for further configuration.

Signed-off-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
---
 drivers/spi/spi.c |  201 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 200 insertions(+), 1 deletion(-)

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 84c2861..e39a484 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -35,6 +35,8 @@
 #include <linux/sched.h>
 #include <linux/delay.h>
 #include <linux/kthread.h>
+#include <linux/ioport.h>
+#include <linux/acpi.h>
 
 static void spidev_release(struct device *dev)
 {
@@ -93,6 +95,10 @@ static int spi_match_device(struct device *dev, struct device_driver *drv)
 	if (of_driver_match_device(dev, drv))
 		return 1;
 
+	/* Then try ACPI */
+	if (acpi_driver_match_device(dev, drv))
+		return 1;
+
 	if (sdrv->id_table)
 		return !!spi_match_id(sdrv->id_table, spi);
 
@@ -888,6 +894,196 @@ static void of_register_spi_devices(struct spi_master *master)
 static void of_register_spi_devices(struct spi_master *master) { }
 #endif
 
+#ifdef CONFIG_ACPI
+static int acpi_spi_add_resource(struct acpi_resource *ares, void *data)
+{
+	struct acpi_resource_spi_serialbus *sb;
+	struct spi_device *spi = data;
+
+	if (ares->type != ACPI_RESOURCE_TYPE_SERIAL_BUS)
+		return 0;
+
+	sb = &ares->data.spi_serial_bus;
+	if (sb->type != ACPI_RESOURCE_SERIAL_TYPE_SPI)
+		return 0;
+
+	spi->chip_select = sb->device_selection;
+	spi->max_speed_hz = sb->connection_speed;
+
+	if (sb->clock_phase == ACPI_SPI_SECOND_PHASE)
+		spi->mode |= SPI_CPHA;
+	if (sb->clock_polarity == ACPI_SPI_START_HIGH)
+		spi->mode |= SPI_CPOL;
+	if (sb->device_polarity == ACPI_SPI_ACTIVE_HIGH)
+		spi->mode |= SPI_CS_HIGH;
+
+	return 1;
+}
+
+static acpi_status acpi_spi_add_device(acpi_handle handle, u32 level,
+				       void *data, void **return_value)
+{
+	struct spi_master *master = data;
+	struct resource_list_entry *rentry;
+	struct list_head resource_list;
+	struct acpi_device *adev;
+	struct spi_device *spi;
+	int ret;
+
+	if (acpi_bus_get_device(handle, &adev))
+		return AE_OK;
+	if (acpi_bus_get_status(adev) || !adev->status.present)
+		return AE_OK;
+
+	spi = spi_alloc_device(master);
+	if (!spi) {
+		dev_err(&master->dev, "failed to allocate SPI device for %s\n",
+			dev_name(&adev->dev));
+		return AE_NO_MEMORY;
+	}
+
+	INIT_LIST_HEAD(&resource_list);
+	ret = acpi_dev_get_resources(adev, &resource_list,
+				     acpi_spi_add_resource, spi);
+	if (ret < 0)
+		goto fail_put_dev;
+
+	list_for_each_entry(rentry, &resource_list, node) {
+		struct resource *r = &rentry->res;
+
+		if (resource_type(r) == IORESOURCE_IRQ) {
+			spi->irq = r->start;
+			break;
+		}
+	}
+
+	acpi_dev_free_resource_list(&resource_list);
+
+	if (!spi->max_speed_hz)
+		goto fail_put_dev;
+
+	strlcpy(spi->modalias, dev_name(&adev->dev), sizeof(spi->modalias));
+	if (spi_add_device(spi)) {
+		dev_err(&master->dev, "failed to add SPI device %s from ACPI\n",
+			dev_name(&adev->dev));
+		goto fail_put_dev;
+	}
+
+	return AE_OK;
+
+fail_put_dev:
+	spi_dev_put(spi);
+
+	return AE_OK;
+}
+
+static void acpi_register_spi_devices(struct spi_master *master)
+{
+	acpi_status status;
+	acpi_handle handle;
+
+	handle = master->dev.acpi_handle;
+	if (!handle)
+		return;
+
+	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, 1,
+				     acpi_spi_add_device, NULL,
+				     master, NULL);
+	if (ACPI_FAILURE(status))
+		dev_warn(&master->dev, "failed to enumerate SPI slaves\n");
+}
+
+struct acpi_spi_find {
+	acpi_handle handle;
+	u16 chip_select;
+	bool found;
+};
+
+static int acpi_spi_find_child_address(struct acpi_resource *ares, void *data)
+{
+	struct acpi_resource_spi_serialbus *sb;
+	struct acpi_spi_find *spi_find = 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;
+
+	if (sb->device_selection == spi_find->chip_select)
+		spi_find->found = true;
+
+	return 1;
+}
+
+static acpi_status acpi_spi_find_child(acpi_handle handle, u32 level,
+				       void *data, void **return_value)
+{
+	struct acpi_spi_find *spi_find = data;
+	struct list_head resource_list;
+	struct acpi_device *adev;
+	int ret;
+
+	if (acpi_bus_get_device(handle, &adev))
+		return AE_OK;
+	if (acpi_bus_get_status(adev) || !adev->status.present)
+		return AE_OK;
+
+	INIT_LIST_HEAD(&resource_list);
+	ret = acpi_dev_get_resources(adev, &resource_list,
+				     acpi_spi_find_child_address, spi_find);
+	if (ret < 0)
+		return AE_OK;
+
+	acpi_dev_free_resource_list(&resource_list);
+
+	if (spi_find->found) {
+		spi_find->handle = handle;
+		return AE_CTRL_TERMINATE;
+	}
+	return AE_OK;
+}
+
+static int acpi_spi_find_device(struct device *dev, acpi_handle *handle)
+{
+	struct spi_device *spi = to_spi_device(dev);
+	struct spi_master *master = spi->master;
+	struct acpi_spi_find spi_find;
+	acpi_handle parent;
+	acpi_status status;
+
+	parent = master->dev.acpi_handle;
+	if (!parent)
+		return -ENODEV;
+
+	memset(&spi_find, 0, sizeof(spi_find));
+	spi_find.chip_select = spi->chip_select;
+
+	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, parent, 1,
+				     acpi_spi_find_child, NULL,
+				     &spi_find, NULL);
+	if (ACPI_FAILURE(status) || !spi_find.handle)
+		return -ENODEV;
+
+	*handle = spi_find.handle;
+	return 0;
+}
+
+static struct acpi_bus_type acpi_spi_bus = {
+	.bus = &spi_bus_type,
+	.find_device = acpi_spi_find_device,
+};
+
+static void acpi_spi_bus_register(void)
+{
+	register_acpi_bus_type(&acpi_spi_bus);
+}
+#else
+static inline void acpi_register_spi_devices(struct spi_master *master) {}
+static inline void acpi_spi_bus_register(void) {}
+#endif /* CONFIG_ACPI */
+
 static void spi_master_release(struct device *dev)
 {
 	struct spi_master *master;
@@ -1023,8 +1219,9 @@ int spi_register_master(struct spi_master *master)
 		spi_match_master_to_boardinfo(master, &bi->board_info);
 	mutex_unlock(&board_lock);
 
-	/* Register devices from the device tree */
+	/* Register devices from the device tree and ACPI */
 	of_register_spi_devices(master);
+	acpi_register_spi_devices(master);
 done:
 	return status;
 }
@@ -1550,6 +1747,8 @@ static int __init spi_init(void)
 	status = class_register(&spi_master_class);
 	if (status < 0)
 		goto err2;
+
+	acpi_spi_bus_register();
 	return 0;
 
 err2:
-- 
1.7.10.4

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