[Intel-gfx] [PATCH 1/2] drm/i915: Get the i2c bus number from the ACPI

[Deepak M]

Currently for executing the i2c MIPI sequence, we are
relaying on the i2c bus bunmber which is specified in the
VBT. But there are cases where different Fab versions of
the board will drive the same chip with different i2c port,
in which case the i2c bus number from the VBT cant be relied
on. To overcome this the i2c bus number is read from the
BIOS acpi table; BIOS can detect the Fab version in runtime
and will store the correct i2c bus number in the ACPI table.

v2 by Deepak:
 - Reading the i2c from the ACPI and storing them in list

Cc: Jani Nikula <jani.nikula at intel.com>
Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
Signed-off-by: Deepak M <m.deepak at intel.com>
---
 drivers/gpu/drm/i915/i915_dma.c   |  2 ++
 drivers/gpu/drm/i915/i915_drv.h   | 11 ++++++++
 drivers/gpu/drm/i915/intel_acpi.c | 59 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 72 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
index 4aa3db6..57be99b 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 f37ac12..5c6279d 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -41,6 +41,7 @@
 #include "intel_lrc.h"
 #include "i915_gem_gtt.h"
 #include "i915_gem_render_state.h"
+#include <linux/acpi.h>
 #include <linux/io-mapping.h>
 #include <linux/i2c.h>
 #include <linux/i2c-algo-bit.h>
@@ -1739,6 +1740,12 @@ struct intel_wm_config {
 	bool sprites_scaled;
 };
 
+struct acpi_i2c_data_node {
+	struct list_head head;
+	int i2c_bus_number;
+	int i2c_slave_address;
+};
+
 struct drm_i915_private {
 	struct drm_device *dev;
 	struct kmem_cache *objects;
@@ -1823,6 +1830,8 @@ struct drm_i915_private {
 	/* backlight registers and fields in struct intel_panel */
 	struct mutex backlight_lock;
 
+	struct list_head acpi_i2c_list;
+
 	/* LVDS info */
 	bool no_aux_handshake;
 
@@ -1892,6 +1901,7 @@ struct drm_i915_private {
 
 	struct i915_workarounds workarounds;
 
+
 	/* Reclocking support */
 	bool render_reclock_avail;
 
@@ -3439,6 +3449,7 @@ 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..afe42ab 100644
--- a/drivers/gpu/drm/i915/intel_acpi.c
+++ b/drivers/gpu/drm/i915/intel_acpi.c
@@ -110,6 +110,65 @@ 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) {
+			struct acpi_i2c_data_node *i2c_entry = NULL;
+
+			resource = sb->resource_source.string_ptr;
+			resource = strstr(resource, "I2C");
+			error = kstrtouint(resource+3, 0, &val);
+			if (error)
+				return error;
+
+			i2c_entry = kzalloc(sizeof(struct acpi_i2c_data_node),
+					GFP_NOWAIT);
+			i2c_entry->i2c_bus_number = val;
+			i2c_entry->i2c_slave_address = sb->slave_address;
+
+			list_add_tail(&i2c_entry->head,
+					&dev_priv->acpi_i2c_list);
+		}
+	}
+
+	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);
+	INIT_LIST_HEAD(&dev_priv->acpi_i2c_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