drm/intel: add pick.h for the various "picker" helpers

Add a shared header that's used by i915, xe, and i915 display.

This allows us to drop the compat-i915-headers/i915_reg_defs.h include
from xe_reg_defs.h. All the register macro helpers were subtly pulled in
from i915 to all of xe through this.

Reviewed-by: Michał Grzelak <michal.grzelak@intel.com>
Acked-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patch.msgid.link/fcd70f3317755bf98a6e7ae88974aa8ba06efd1e.1772042022.git.jani.nikula@intel.com
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

4 files changed, 56 insertions, 46 deletions

diff --git a/drivers/gpu/drm/i915/i915_reg_defs.h b/drivers/gpu/drm/i915/i915_reg_defs.h
index a1dc7ff2bef7..e897d3ccbf9e 100644
--- a/drivers/gpu/drm/i915/i915_reg_defs.h
+++ b/drivers/gpu/drm/i915/i915_reg_defs.h
@@ -6,52 +6,9 @@
 #ifndef __I915_REG_DEFS__
 #define __I915_REG_DEFS__
 
+#include <drm/intel/pick.h>
 #include <drm/intel/reg_bits.h>
 
-/*
- * Given the first two numbers __a and __b of arbitrarily many evenly spaced
- * numbers, pick the 0-based __index'th value.
- *
- * Always prefer this over _PICK() if the numbers are evenly spaced.
- */
-#define _PICK_EVEN(__index, __a, __b) ((__a) + (__index) * ((__b) - (__a)))
-
-/*
- * Like _PICK_EVEN(), but supports 2 ranges of evenly spaced address offsets.
- * @__c_index corresponds to the index in which the second range starts to be
- * used. Using math interval notation, the first range is used for indexes [ 0,
- * @__c_index), while the second range is used for [ @__c_index, ... ). Example:
- *
- * #define _FOO_A			0xf000
- * #define _FOO_B			0xf004
- * #define _FOO_C			0xf008
- * #define _SUPER_FOO_A			0xa000
- * #define _SUPER_FOO_B			0xa100
- * #define FOO(x)			_MMIO(_PICK_EVEN_2RANGES(x, 3,		\
- *					      _FOO_A, _FOO_B,			\
- *					      _SUPER_FOO_A, _SUPER_FOO_B))
- *
- * This expands to:
- *	0: 0xf000,
- *	1: 0xf004,
- *	2: 0xf008,
- *	3: 0xa000,
- *	4: 0xa100,
- *	5: 0xa200,
- *	...
- */
-#define _PICK_EVEN_2RANGES(__index, __c_index, __a, __b, __c, __d)		\
-	(BUILD_BUG_ON_ZERO(!__is_constexpr(__c_index)) +			\
-	 ((__index) < (__c_index) ? _PICK_EVEN(__index, __a, __b) :		\
-				   _PICK_EVEN((__index) - (__c_index), __c, __d)))
-
-/*
- * Given the arbitrary numbers in varargs, pick the 0-based __index'th number.
- *
- * Always prefer _PICK_EVEN() over this if the numbers are evenly spaced.
- */
-#define _PICK(__index, ...) (((const u32 []){ __VA_ARGS__ })[__index])
-
 typedef struct {
 	u32 reg;
 } i915_reg_t;
diff --git a/drivers/gpu/drm/xe/compat-i915-headers/intel_uncore.h b/drivers/gpu/drm/xe/compat-i915-headers/intel_uncore.h
index c5e198ace7bc..a8cfd65119e0 100644
--- a/drivers/gpu/drm/xe/compat-i915-headers/intel_uncore.h
+++ b/drivers/gpu/drm/xe/compat-i915-headers/intel_uncore.h
@@ -6,6 +6,7 @@
 #ifndef __INTEL_UNCORE_H__
 #define __INTEL_UNCORE_H__
 
+#include "i915_reg_defs.h"
 #include "xe_device.h"
 #include "xe_device_types.h"
 #include "xe_mmio.h"
diff --git a/drivers/gpu/drm/xe/regs/xe_reg_defs.h b/drivers/gpu/drm/xe/regs/xe_reg_defs.h
index c39aab843e35..27ac0bf1f6cd 100644
--- a/drivers/gpu/drm/xe/regs/xe_reg_defs.h
+++ b/drivers/gpu/drm/xe/regs/xe_reg_defs.h
@@ -6,12 +6,13 @@
 #ifndef _XE_REG_DEFS_H_
 #define _XE_REG_DEFS_H_
 
+#include <drm/intel/pick.h>
+#include <drm/intel/reg_bits.h>
+
 #include <linux/build_bug.h>
 #include <linux/log2.h>
 #include <linux/sizes.h>
 
-#include "compat-i915-headers/i915_reg_defs.h"
-
 /**
  * XE_REG_ADDR_MAX - The upper limit on MMIO register address
  *
diff --git a/include/drm/intel/pick.h b/include/drm/intel/pick.h
new file mode 100644
index 000000000000..d976fab8f270
--- /dev/null
+++ b/include/drm/intel/pick.h
@@ -0,0 +1,51 @@
+/* SPDX-License-Identifier: MIT */
+/* Copyright © 2026 Intel Corporation */
+
+#ifndef _PICK_H_
+#define _PICK_H_
+
+/*
+ * Given the first two numbers __a and __b of arbitrarily many evenly spaced
+ * numbers, pick the 0-based __index'th value.
+ *
+ * Always prefer this over _PICK() if the numbers are evenly spaced.
+ */
+#define _PICK_EVEN(__index, __a, __b) ((__a) + (__index) * ((__b) - (__a)))
+
+/*
+ * Like _PICK_EVEN(), but supports 2 ranges of evenly spaced address offsets.
+ * @__c_index corresponds to the index in which the second range starts to be
+ * used. Using math interval notation, the first range is used for indexes [ 0,
+ * @__c_index), while the second range is used for [ @__c_index, ... ). Example:
+ *
+ * #define _FOO_A			0xf000
+ * #define _FOO_B			0xf004
+ * #define _FOO_C			0xf008
+ * #define _SUPER_FOO_A			0xa000
+ * #define _SUPER_FOO_B			0xa100
+ * #define FOO(x)			_MMIO(_PICK_EVEN_2RANGES(x, 3,		\
+ *					      _FOO_A, _FOO_B,			\
+ *					      _SUPER_FOO_A, _SUPER_FOO_B))
+ *
+ * This expands to:
+ *	0: 0xf000,
+ *	1: 0xf004,
+ *	2: 0xf008,
+ *	3: 0xa000,
+ *	4: 0xa100,
+ *	5: 0xa200,
+ *	...
+ */
+#define _PICK_EVEN_2RANGES(__index, __c_index, __a, __b, __c, __d)		\
+	(BUILD_BUG_ON_ZERO(!__is_constexpr(__c_index)) +			\
+	 ((__index) < (__c_index) ? _PICK_EVEN(__index, __a, __b) :		\
+				   _PICK_EVEN((__index) - (__c_index), __c, __d)))
+
+/*
+ * Given the arbitrary numbers in varargs, pick the 0-based __index'th number.
+ *
+ * Always prefer _PICK_EVEN() over this if the numbers are evenly spaced.
+ */
+#define _PICK(__index, ...) (((const u32 []){ __VA_ARGS__ })[__index])
+
+#endif