cpufreq: CPPC: Add generic helpers for sysfs show/store

Add generic helper functions for u64 sysfs attributes that follow the
common pattern of calling CPPC get/set APIs:
 - cppc_cpufreq_sysfs_show_u64(): reads value and handles -EOPNOTSUPP
 - cppc_cpufreq_sysfs_store_u64(): parses input and calls set function

Add CPPC_CPUFREQ_ATTR_RW_U64() macro to generate show/store functions
using these helpers, reducing boilerplate for simple attributes.

Convert auto_act_window and energy_performance_preference_val to use
the new macro.

No functional changes.

Signed-off-by: Sumit Gupta <sumitg@nvidia.com>
Reviewed-by: Lifeng Zheng <zhenglifeng1@huawei.com>
[ rjw: Retained empty code line after a conditional ]
Link: https://patch.msgid.link/20260120145623.2959636-2-sumitg@nvidia.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Author: Sumit Gupta

drivers/cpufreq/cppc_cpufreq.c

@@ -863,14 +863,13 @@ static ssize_t store_auto_select(struct cpufreq_policy *policy,
 	return count;
 }
 
-static ssize_t show_auto_act_window(struct cpufreq_policy *policy, char *buf)
+static ssize_t cppc_cpufreq_sysfs_show_u64(unsigned int cpu,
+					   int (*get_func)(int, u64 *),
+					   char *buf)
 {
 	u64 val;
-	int ret;
-
-	ret = cppc_get_auto_act_window(policy->cpu, &val);
+	int ret = get_func((int)cpu, &val);
 
-	/* show "<unsupported>" when this register is not supported by cpc */
 	if (ret == -EOPNOTSUPP)
 		return sysfs_emit(buf, "<unsupported>\n");
 
@@ -880,56 +879,39 @@ static ssize_t show_auto_act_window(struct cpufreq_policy *policy, char *buf)
 	return sysfs_emit(buf, "%llu\n", val);
 }
 
-static ssize_t store_auto_act_window(struct cpufreq_policy *policy,
-				     const char *buf, size_t count)
+static ssize_t cppc_cpufreq_sysfs_store_u64(unsigned int cpu,
+					    int (*set_func)(int, u64),
+					    const char *buf, size_t count)
 {
-	u64 usec;
+	u64 val;
 	int ret;
 
-	ret = kstrtou64(buf, 0, &usec);
+	ret = kstrtou64(buf, 0, &val);
 	if (ret)
 		return ret;
 
-	ret = cppc_set_auto_act_window(policy->cpu, usec);
-	if (ret)
-		return ret;
+	ret = set_func((int)cpu, val);
 
-	return count;
+	return ret ? ret : count;
 }
 
-static ssize_t show_energy_performance_preference_val(struct cpufreq_policy *policy, char *buf)
-{
-	u64 val;
-	int ret;
-
-	ret = cppc_get_epp_perf(policy->cpu, &val);
-
-	/* show "<unsupported>" when this register is not supported by cpc */
-	if (ret == -EOPNOTSUPP)
-		return sysfs_emit(buf, "<unsupported>\n");
-
-	if (ret)
-		return ret;
-
-	return sysfs_emit(buf, "%llu\n", val);
+#define CPPC_CPUFREQ_ATTR_RW_U64(_name, _get_func, _set_func)		\
+static ssize_t show_##_name(struct cpufreq_policy *policy, char *buf)	\
+{									\
+	return cppc_cpufreq_sysfs_show_u64(policy->cpu, _get_func, buf);\
+}									\
+static ssize_t store_##_name(struct cpufreq_policy *policy,		\
+			     const char *buf, size_t count)		\
+{									\
+	return cppc_cpufreq_sysfs_store_u64(policy->cpu, _set_func,	\
+					    buf, count);		\
 }
 
-static ssize_t store_energy_performance_preference_val(struct cpufreq_policy *policy,
-						       const char *buf, size_t count)
-{
-	u64 val;
-	int ret;
-
-	ret = kstrtou64(buf, 0, &val);
-	if (ret)
-		return ret;
-
-	ret = cppc_set_epp(policy->cpu, val);
-	if (ret)
-		return ret;
+CPPC_CPUFREQ_ATTR_RW_U64(auto_act_window, cppc_get_auto_act_window,
+			 cppc_set_auto_act_window)
 
-	return count;
-}
+CPPC_CPUFREQ_ATTR_RW_U64(energy_performance_preference_val,
+			 cppc_get_epp_perf, cppc_set_epp)
 
 cpufreq_freq_attr_ro(freqdomain_cpus);
 cpufreq_freq_attr_rw(auto_select);