[PATCH] drm/i915: Get the i2c bus number from the ACPI

[Deepak M <m.deepak@xxxxxxxxx>]

Currently for executing the i2c MIPI sequence, we are
relaying on the i2c bus bunmber which is specified in the
VBT.

Signed-off-by: Deepak M <m.deepak@xxxxxxxxx>
---
 drivers/gpu/drm/i915/i915_dma.c   |  2 ++
 drivers/gpu/drm/i915/i915_drv.h   |  7 ++++++
 drivers/gpu/drm/i915/intel_acpi.c | 49 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 58 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
index 1c6d227..8cd1d9d 100644
--- a/drivers/gpu/drm/i915/i915_dma.c
+++ b/drivers/gpu/drm/i915/i915_dma.c
@@ -387,6 +387,8 @@ static int i915_load_modeset_init(struct drm_device *dev)
 
 	intel_register_dsm_handler();
 
+	intel_acpi_find_i2c(dev_priv);
+
 	ret = vga_switcheroo_register_client(dev->pdev, &i915_switcheroo_ops, false);
 	if (ret)
 		goto cleanup_vga_client;
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 6644c2e..6fe8b64 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -47,6 +47,7 @@
 #include <drm/intel-gtt.h>
 #include <drm/drm_legacy.h> /* for struct drm_dma_handle */
 #include <drm/drm_gem.h>
+#include <linux/acpi.h>
 #include <linux/backlight.h>
 #include <linux/hashtable.h>
 #include <linux/intel-iommu.h>
@@ -1880,6 +1881,11 @@ struct drm_i915_private {
 
 	struct i915_workarounds workarounds;
 
+	struct {
+		int i2c_bus_number;
+		int i2c_slave_address;
+	} acpi_data;
+
 	/* Reclocking support */
 	bool render_reclock_avail;
 
@@ -3426,6 +3432,7 @@ intel_opregion_notify_adapter(struct drm_device *dev, pci_power_t state)
 #ifdef CONFIG_ACPI
 extern void intel_register_dsm_handler(void);
 extern void intel_unregister_dsm_handler(void);
+extern acpi_status intel_acpi_find_i2c(struct drm_i915_private *dev_priv);
 #else
 static inline void intel_register_dsm_handler(void) { return; }
 static inline void intel_unregister_dsm_handler(void) { return; }
diff --git a/drivers/gpu/drm/i915/intel_acpi.c b/drivers/gpu/drm/i915/intel_acpi.c
index eb638a1..f62be5c 100644
--- a/drivers/gpu/drm/i915/intel_acpi.c
+++ b/drivers/gpu/drm/i915/intel_acpi.c
@@ -110,6 +110,55 @@ static void intel_dsm_platform_mux_info(void)
 	ACPI_FREE(pkg);
 }
 
+static int i2c_acpi_get_name(struct acpi_resource *ares, void *data)
+{
+	struct drm_i915_private *dev_priv = data;
+	struct acpi_resource_i2c_serialbus *sb;
+	unsigned int val;
+	char *resource;
+	int error;
+
+	if (ares->type == ACPI_RESOURCE_TYPE_SERIAL_BUS) {
+		sb = &ares->data.i2c_serial_bus;
+
+		if (sb->type == ACPI_RESOURCE_SERIAL_TYPE_I2C) {
+			resource = sb->resource_source.string_ptr;
+			resource = strstr(resource, "I2C");
+			error = kstrtouint(resource+3, 0, &val);
+			if (error)
+				return error;
+			dev_priv->acpi_data.i2c_bus_number = val;
+			dev_priv->acpi_data.i2c_slave_address =
+						sb->slave_address;
+		}
+	}
+	return 1;
+}
+
+acpi_status intel_acpi_find_i2c(struct drm_i915_private *dev_priv)
+{
+	struct pci_dev *pdev = dev_priv->dev->pdev;
+	struct list_head resource_list;
+	struct acpi_device *adev;
+	acpi_handle dhandle;
+
+	dhandle = ACPI_HANDLE(&pdev->dev);
+	if (!dhandle)
+		return false;
+
+	if (acpi_bus_get_device(dhandle, &adev))
+		return AE_OK;
+	if (acpi_bus_get_status(adev) || !adev->status.present)
+		return AE_OK;
+
+	INIT_LIST_HEAD(&resource_list);
+	acpi_dev_get_resources(adev, &resource_list,
+			i2c_acpi_get_name, dev_priv);
+	acpi_dev_free_resource_list(&resource_list);
+
+	return AE_OK;
+}
+
 static bool intel_dsm_pci_probe(struct pci_dev *pdev)
 {
 	acpi_handle dhandle;
-- 
1.9.1

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