Add attributes only for registers that are supported by the platform.
This prevents unsupported, optional registers from having sysfs entries
created.

Signed-off-by: Janakarajan Natarajan <janakarajan.natara...@amd.com>
---
 drivers/acpi/cppc_acpi.c | 82 +++++++++++++++++++++++++++++++++-------
 1 file changed, 68 insertions(+), 14 deletions(-)

diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
index c43de65531ae..53a9dc9960b6 100644
--- a/drivers/acpi/cppc_acpi.c
+++ b/drivers/acpi/cppc_acpi.c
@@ -183,22 +183,8 @@ static ssize_t show_feedback_ctrs(struct kobject *kobj,
 }
 define_one_cppc_ro(feedback_ctrs);
 
-static struct attribute *cppc_attrs[] = {
-       &feedback_ctrs.attr,
-       &reference_perf.attr,
-       &wraparound_time.attr,
-       &highest_perf.attr,
-       &lowest_perf.attr,
-       &lowest_nonlinear_perf.attr,
-       &nominal_perf.attr,
-       &nominal_freq.attr,
-       &lowest_freq.attr,
-       NULL
-};
-
 static struct kobj_type cppc_ktype = {
        .sysfs_ops = &kobj_sysfs_ops,
-       .default_attrs = cppc_attrs,
 };
 
 static int check_pcc_chan(int pcc_ss_id, bool chk_err_bit)
@@ -733,6 +719,69 @@ static bool is_buf_only(int reg_idx)
                                 CPC_SUP_BUFFER_ONLY(&cpc->cpc_regs[idx]) : \
                                 CPC_SUPPORTED(&cpc->cpc_regs[idx]))
 
+static int is_mandatory_reg(int reg_idx)
+{
+       switch (reg_idx) {
+       case HIGHEST_PERF:
+       case NOMINAL_PERF:
+       case LOW_NON_LINEAR_PERF:
+       case LOWEST_PERF:
+       case REFERENCE_CTR:
+       case DELIVERED_CTR:
+               return 1;
+       }
+
+       return 0;
+}
+
+#define MANDATORY_REG_CNT      6
+
+static int set_cppc_attrs(struct cpc_desc *cpc, int entries)
+{
+       int i, attr_i = 0, opt_reg_cnt;
+       static struct attribute **cppc_attrs;
+
+       cppc_attrs = kcalloc(entries, sizeof(*cppc_attrs), GFP_KERNEL);
+       if (!cppc_attrs)
+               return -ENOMEM;
+
+       /* Set optional regs */
+       opt_reg_cnt = entries - MANDATORY_REG_CNT;
+       for (i = 0; i < MAX_CPC_REG_ENT && attr_i < opt_reg_cnt; i++) {
+               if (is_mandatory_reg(i) || !REG_SUPPORTED(cpc, i))
+                       continue;
+
+               switch (i) {
+               case NOMINAL_FREQ:
+                       cppc_attrs[attr_i++] = &nominal_freq.attr;
+                       break;
+               case LOWEST_FREQ:
+                       cppc_attrs[attr_i++] = &lowest_freq.attr;
+                       break;
+               case REFERENCE_PERF:
+                       cppc_attrs[attr_i++] = &reference_perf.attr;
+                       break;
+               case CTR_WRAP_TIME:
+                       cppc_attrs[attr_i++] = &wraparound_time.attr;
+                       break;
+               }
+       }
+
+       /* Set mandatory regs */
+       cppc_attrs[attr_i++] = &highest_perf.attr;
+       cppc_attrs[attr_i++] = &nominal_perf.attr;
+       cppc_attrs[attr_i++] = &lowest_nonlinear_perf.attr;
+       cppc_attrs[attr_i++] = &lowest_perf.attr;
+
+       /* Set feedback_ctr sysfs entry */
+       cppc_attrs[attr_i] = &feedback_ctrs.attr;
+
+       /* Set kobj_type member */
+       cppc_ktype.default_attrs = cppc_attrs;
+
+       return 0;
+}
+
 /**
  * acpi_cppc_processor_probe - Search for per CPU _CPC objects.
  * @pr: Ptr to acpi_processor containing this CPU's logical ID.
@@ -887,6 +936,10 @@ int acpi_cppc_processor_probe(struct acpi_processor *pr)
        /* Plug PSD data into this CPU's CPC descriptor. */
        per_cpu(cpc_desc_ptr, pr->id) = cpc_ptr;
 
+       ret = set_cppc_attrs(cpc_ptr, num_ent - 2);
+       if (ret)
+               goto out_free;
+
        ret = kobject_init_and_add(&cpc_ptr->kobj, &cppc_ktype, &cpu_dev->kobj,
                        "acpi_cppc");
        if (ret) {
@@ -948,6 +1001,7 @@ void acpi_cppc_processor_exit(struct acpi_processor *pr)
                        iounmap(addr);
        }
 
+       kfree(cppc_ktype.default_attrs);
        kobject_put(&cpc_ptr->kobj);
        kfree(cpc_ptr);
 }
-- 
2.17.1

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