1 files changed, 322 insertions, 0 deletions
diff --git a/drivers/firmware/arm_scmi/quirks.c b/drivers/firmware/arm_scmi/quirks.c
new file mode 100644
index 000000000000..03960aca3610
--- /dev/null
+++ b/drivers/firmware/arm_scmi/quirks.c
@@ -0,0 +1,322 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * System Control and Management Interface (SCMI) Message Protocol Quirks
+ *
+ * Copyright (C) 2025 ARM Ltd.
+ */
+
+/**
+ * DOC: Theory of operation
+ *
+ * A framework to define SCMI quirks and their activation conditions based on
+ * existing static_keys kernel facilities.
+ *
+ * Quirks are named and their activation conditions defined using the macro
+ * DEFINE_SCMI_QUIRK() in this file.
+ *
+ * After a quirk is defined, a corresponding entry must also be added to the
+ * global @scmi_quirks_table in this file using __DECLARE_SCMI_QUIRK_ENTRY().
+ *
+ * Additionally a corresponding quirk declaration must be added also to the
+ * quirk.h file using DECLARE_SCMI_QUIRK().
+ *
+ * The needed quirk code-snippet itself will be defined local to the SCMI code
+ * that is meant to fix and will be associated to the previously defined quirk
+ * and related activation conditions using the macro SCMI_QUIRK().
+ *
+ * At runtime, during the SCMI stack probe sequence, once the SCMI Server had
+ * advertised the running platform Vendor, SubVendor and Implementation Version
+ * data, all the defined quirks matching the activation conditions will be
+ * enabled.
+ *
+ * Example
+ *
+ * quirk.c
+ * -------
+ *  DEFINE_SCMI_QUIRK(fix_me, "vendor", "subvend", "0x12000-0x30000",
+ *		      "someone,plat_A", "another,plat_b", "vend,sku");
+ *
+ *  static struct scmi_quirk *scmi_quirks_table[] = {
+ *	...
+ *	__DECLARE_SCMI_QUIRK_ENTRY(fix_me),
+ *	NULL
+ *  };
+ *
+ * quirk.h
+ * -------
+ *  DECLARE_SCMI_QUIRK(fix_me);
+ *
+ * <somewhere_in_the_scmi_stack.c>
+ * ------------------------------
+ *
+ *  #define QUIRK_CODE_SNIPPET_FIX_ME()		\
+ *  ({						\
+ *	if (p->condition)			\
+ *		a_ptr->calculated_val = 123;	\
+ *  })
+ *
+ *
+ *  int some_function_to_fix(int param, struct something *p)
+ *  {
+ *	struct some_strut *a_ptr;
+ *
+ *	a_ptr = some_load_func(p);
+ *	SCMI_QUIRK(fix_me, QUIRK_CODE_SNIPPET_FIX_ME);
+ *	some_more_func(a_ptr);
+ *	...
+ *
+ *	return 0;
+ *  }
+ *
+ */
+
+#include <linux/ctype.h>
+#include <linux/device.h>
+#include <linux/export.h>
+#include <linux/hashtable.h>
+#include <linux/kstrtox.h>
+#include <linux/of.h>
+#include <linux/slab.h>
+#include <linux/static_key.h>
+#include <linux/string.h>
+#include <linux/stringhash.h>
+#include <linux/types.h>
+
+#include "quirks.h"
+
+#define SCMI_QUIRKS_HT_SZ	4
+
+struct scmi_quirk {
+	bool enabled;
+	const char *name;
+	char *vendor;
+	char *sub_vendor_id;
+	char *impl_ver_range;
+	u32 start_range;
+	u32 end_range;
+	struct static_key_false *key;
+	struct hlist_node hash;
+	unsigned int hkey;
+	const char *const compats[];
+};
+
+#define __DEFINE_SCMI_QUIRK_ENTRY(_qn, _ven, _sub, _impl, ...)	\
+	static struct scmi_quirk scmi_quirk_entry_ ## _qn = {		\
+		.name = __stringify(quirk_ ## _qn),			\
+		.vendor = _ven,						\
+		.sub_vendor_id = _sub,					\
+		.impl_ver_range = _impl,				\
+		.key = &(scmi_quirk_ ## _qn),				\
+		.compats = { __VA_ARGS__ __VA_OPT__(,) NULL },		\
+	}
+
+#define __DECLARE_SCMI_QUIRK_ENTRY(_qn)		(&(scmi_quirk_entry_ ## _qn))
+
+/*
+ * Define a quirk by name and provide the matching tokens where:
+ *
+ *  _qn: A string which will be used to build the quirk and the global
+ *	 static_key names.
+ *  _ven : SCMI Vendor ID string match, NULL means any.
+ *  _sub : SCMI SubVendor ID string match, NULL means any.
+ *  _impl : SCMI Implementation Version string match, NULL means any.
+ *          This string can be used to express version ranges which will be
+ *          interpreted as follows:
+ *
+ *			NULL		[0, 0xFFFFFFFF]
+ *			"X"		[X, X]
+ *			"X-"		[X, 0xFFFFFFFF]
+ *			"-X"		[0, X]
+ *			"X-Y"		[X, Y]
+ *
+ *          with X <= Y and <v> in [X, Y] meaning X <= <v> <= Y
+ *
+ *  ... : An optional variadic macros argument used to provide a comma-separated
+ *	  list of compatible strings matches; when no variadic argument is
+ *	  provided, ANY compatible will match this quirk.
+ *
+ *  This implicitly define also a properly named global static-key that
+ *  will be used to dynamically enable the quirk at initialization time.
+ *
+ *  Note that it is possible to associate multiple quirks to the same
+ *  matching pattern, if your firmware quality is really astounding :P
+ *
+ * Example:
+ *
+ * Compatibles list NOT provided, so ANY compatible will match:
+ *
+ *  DEFINE_SCMI_QUIRK(my_new_issue, "Vend", "SVend", "0x12000-0x30000");
+ *
+ *
+ * A few compatibles provided to match against:
+ *
+ *  DEFINE_SCMI_QUIRK(my_new_issue, "Vend", "SVend", "0x12000-0x30000",
+ *		      "xvend,plat_a", "xvend,plat_b", "xvend,sku_name");
+ */
+#define DEFINE_SCMI_QUIRK(_qn, _ven, _sub, _impl, ...)			\
+	DEFINE_STATIC_KEY_FALSE(scmi_quirk_ ## _qn);			\
+	__DEFINE_SCMI_QUIRK_ENTRY(_qn, _ven, _sub, _impl, ##__VA_ARGS__)
+
+/*
+ * Same as DEFINE_SCMI_QUIRK but EXPORTED: this is meant to address quirks
+ * that possibly reside in code that is included in loadable kernel modules
+ * that needs to be able to access the global static keys at runtime to
+ * determine if enabled or not. (see SCMI_QUIRK to understand usage)
+ */
+#define DEFINE_SCMI_QUIRK_EXPORTED(_qn, _ven, _sub, _impl, ...)		\
+	DEFINE_STATIC_KEY_FALSE(scmi_quirk_ ## _qn);			\
+	EXPORT_SYMBOL_GPL(scmi_quirk_ ## _qn);				\
+	__DEFINE_SCMI_QUIRK_ENTRY(_qn, _ven, _sub, _impl, ##__VA_ARGS__)
+
+/* Global Quirks Definitions */
+DEFINE_SCMI_QUIRK(clock_rates_triplet_out_of_spec, NULL, NULL, NULL);
+DEFINE_SCMI_QUIRK(perf_level_get_fc_force, "Qualcomm", NULL, "0x20000-");
+
+/*
+ * Quirks Pointers Array
+ *
+ * This is filled at compile-time with the list of pointers to all the currently
+ * defined quirks descriptors.
+ */
+static struct scmi_quirk *scmi_quirks_table[] = {
+	__DECLARE_SCMI_QUIRK_ENTRY(clock_rates_triplet_out_of_spec),
+	__DECLARE_SCMI_QUIRK_ENTRY(perf_level_get_fc_force),
+	NULL
+};
+
+/*
+ * Quirks HashTable
+ *
+ * A run-time populated hashtable containing all the defined quirks descriptors
+ * hashed by matching pattern.
+ */
+static DEFINE_READ_MOSTLY_HASHTABLE(scmi_quirks_ht, SCMI_QUIRKS_HT_SZ);
+
+static unsigned int scmi_quirk_signature(const char *vend, const char *sub_vend)
+{
+	char *signature, *p;
+	unsigned int hash32;
+	unsigned long hash = 0;
+
+	/* vendor_id/sub_vendor_id guaranteed <= SCMI_SHORT_NAME_MAX_SIZE */
+	signature = kasprintf(GFP_KERNEL, "|%s|%s|", vend ?: "", sub_vend ?: "");
+	if (!signature)
+		return 0;
+
+	pr_debug("SCMI Quirk Signature >>>%s<<<\n", signature);
+
+	p = signature;
+	while (*p)
+		hash = partial_name_hash(tolower(*p++), hash);
+	hash32 = end_name_hash(hash);
+
+	kfree(signature);
+
+	return hash32;
+}
+
+static int scmi_quirk_range_parse(struct scmi_quirk *quirk)
+{
+	const char *last, *first = quirk->impl_ver_range;
+	size_t len;
+	char *sep;
+	int ret;
+
+	quirk->start_range = 0;
+	quirk->end_range = 0xFFFFFFFF;
+	len = quirk->impl_ver_range ? strlen(quirk->impl_ver_range) : 0;
+	if (!len)
+		return 0;
+
+	last = first + len - 1;
+	sep = strchr(quirk->impl_ver_range, '-');
+	if (sep)
+		*sep = '\0';
+
+	if (sep == first) /* -X */
+		ret = kstrtouint(first + 1, 0, &quirk->end_range);
+	else /* X OR X- OR X-y */
+		ret = kstrtouint(first, 0, &quirk->start_range);
+	if (ret)
+		return ret;
+
+	if (!sep)
+		quirk->end_range = quirk->start_range;
+	else if (sep != last) /* x-Y */
+		ret = kstrtouint(sep + 1, 0, &quirk->end_range);
+
+	if (quirk->start_range > quirk->end_range)
+		return -EINVAL;
+
+	return ret;
+}
+
+void scmi_quirks_initialize(void)
+{
+	struct scmi_quirk *quirk;
+	int i;
+
+	for (i = 0, quirk = scmi_quirks_table[0]; quirk;
+	     i++, quirk = scmi_quirks_table[i]) {
+		int ret;
+
+		ret = scmi_quirk_range_parse(quirk);
+		if (ret) {
+			pr_err("SCMI skip QUIRK [%s] - BAD RANGE - |%s|\n",
+			       quirk->name, quirk->impl_ver_range);
+			continue;
+		}
+		quirk->hkey = scmi_quirk_signature(quirk->vendor,
+						   quirk->sub_vendor_id);
+
+		hash_add(scmi_quirks_ht, &quirk->hash, quirk->hkey);
+
+		pr_debug("Registered SCMI QUIRK [%s] -- %p - Key [0x%08X] - %s/%s/[0x%08X-0x%08X]\n",
+			 quirk->name, quirk, quirk->hkey,
+			 quirk->vendor, quirk->sub_vendor_id,
+			 quirk->start_range, quirk->end_range);
+	}
+
+	pr_debug("SCMI Quirks initialized\n");
+}
+
+void scmi_quirks_enable(struct device *dev, const char *vend,
+			const char *subv, const u32 impl)
+{
+	for (int i = 3; i >= 0; i--) {
+		struct scmi_quirk *quirk;
+		unsigned int hkey;
+
+		hkey = scmi_quirk_signature(i > 1 ? vend : NULL,
+					    i > 2 ? subv : NULL);
+
+		/*
+		 * Note that there could be multiple matches so we
+		 * will enable multiple quirk part of a hash collision
+		 * domain...BUT we cannot assume that ALL quirks on the
+		 * same collision domain are a full match.
+		 */
+		hash_for_each_possible(scmi_quirks_ht, quirk, hash, hkey) {
+			if (quirk->enabled || quirk->hkey != hkey ||
+			    impl < quirk->start_range ||
+			    impl > quirk->end_range)
+				continue;
+
+			if (quirk->compats[0] &&
+			    !of_machine_compatible_match(quirk->compats))
+				continue;
+
+			dev_info(dev, "Enabling SCMI Quirk [%s]\n",
+				 quirk->name);
+
+			dev_dbg(dev,
+				"Quirk matched on: %s/%s/%s/[0x%08X-0x%08X]\n",
+				quirk->compats[0], quirk->vendor,
+				quirk->sub_vendor_id,
+				quirk->start_range, quirk->end_range);
+
+			static_branch_enable(quirk->key);
+			quirk->enabled = true;
+		}
+	}
+}