i2c/drivers/generic: Add support for including a CDM

Chip Direct Mapping is exclusive to Windows; it allows specifying the
position where a chip is mounted. There are 8 positions and a _CDM
method should return 0xabcd0X, where X is the position.

Tested by booting Windows 11 on the StarLite Mk V, rotating the device
and checking the orientation is correct, where previously, it was
inverted.

Change-Id: If70c25288d835df7064b4051c43abeb2d6531f3b
Signed-off-by: Sean Rhodes <sean@starlabs.systems>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/81409
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/drivers/i2c/generic/chip.h

@@ -81,6 +81,31 @@ struct drivers_i2c_generic_config {
 	bool has_rotation_matrix;
 	int rotation_matrix[9];
 
+	/*
+	 * Chip Direct Mapping is exclusive to Windows, a allows specifying the
+	 * position where a chip is mounted. There are 8 positions:
+	 *	1:	90 Degrees
+	 *	2:	270 Degrees
+	 *	3:	180 Degrees
+	 *	4:	0 Degrees
+	 *	5:	90 Degrees (Inverted)
+	 *	6:	270 Degrees (Inverted)
+	 *	7:	180 Degrees (Inverted)
+	 *	8:	0 Degrees (Inverted)
+	 *
+	 * The _CDM method should return 0xabcd0X, where X is the position.
+	 */
+	enum {
+		CDM_NOT_PRESENT = 0,
+		CDM_ROT_90,
+		CDM_ROT_180,
+		CDM_ROT_270,
+		CDM_ROT_0,
+		CDM_ROT_90_INVERT,
+		CDM_ROT_180_INVERT,
+		CDM_ROT_270_INVERT,
+		CDM_ROT_0_INVERT,
+	} cdm_index;
 
 	/* Generic properties for exporting device-specific data to the OS */
 	struct acpi_dp property_list[MAX_GENERIC_PROPERTY_LIST];

src/drivers/i2c/generic/generic.c

@@ -165,6 +165,13 @@ void i2c_generic_fill_ssdt(const struct device *dev,
 		acpigen_pop_len();
 	}
 
+	/* Chip Direct Mapping */
+	if (config->cdm_index != CDM_NOT_PRESENT) {
+		acpigen_write_method("_CDM", 1);
+		acpigen_write_return_integer(0xabcd00 | config->cdm_index);
+		acpigen_pop_len();
+	}
+
 	/* Callback if any. */
 	if (callback)
 		callback(dev);