--- /dev/null
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Platform energy and frequency attributes driver
+ *
+ * This driver creates a sys file at /sys/firmware/papr/ which encapsulates a
+ * directory structure containing files in keyword - value pairs that specify
+ * energy and frequency configuration of the system.
+ *
+ * The format of exposing the sysfs information is as follows:
+ * /sys/firmware/papr/energy_scale_info/
+ * |-- <id>/
+ * |-- desc
+ * |-- value
+ * |-- value_desc (if exists)
+ * |-- <id>/
+ * |-- desc
+ * |-- value
+ * |-- value_desc (if exists)
+ *
+ * Copyright 2022 IBM Corp.
+ */
+
+#include <asm/hvcall.h>
+#include <asm/machdep.h>
+
+#include "pseries.h"
+
+/*
+ * Flag attributes to fetch either all or one attribute from the HCALL
+ * flag = BE(0) => fetch all attributes with firstAttributeId = 0
+ * flag = BE(1) => fetch a single attribute with firstAttributeId = id
+ */
+#define ESI_FLAGS_ALL 0
+#define ESI_FLAGS_SINGLE (1ull << 63)
+
+#define KOBJ_MAX_ATTRS 3
+
+#define ESI_HDR_SIZE sizeof(struct h_energy_scale_info_hdr)
+#define ESI_ATTR_SIZE sizeof(struct energy_scale_attribute)
+#define CURR_MAX_ESI_ATTRS 8
+
+struct energy_scale_attribute {
+ __be64 id;
+ __be64 val;
+ u8 desc[64];
+ u8 value_desc[64];
+} __packed;
+
+struct h_energy_scale_info_hdr {
+ __be64 num_attrs;
+ __be64 array_offset;
+ u8 data_header_version;
+} __packed;
+
+struct papr_attr {
+ u64 id;
+ struct kobj_attribute kobj_attr;
+};
+
+struct papr_group {
+ struct attribute_group pg;
+ struct papr_attr pgattrs[KOBJ_MAX_ATTRS];
+};
+
+static struct papr_group *papr_groups;
+/* /sys/firmware/papr */
+static struct kobject *papr_kobj;
+/* /sys/firmware/papr/energy_scale_info */
+static struct kobject *esi_kobj;
+
+/*
+ * Energy modes can change dynamically hence making a new hcall each time the
+ * information needs to be retrieved
+ */
+static int papr_get_attr(u64 id, struct energy_scale_attribute *esi)
+{
+ int esi_buf_size = ESI_HDR_SIZE + (CURR_MAX_ESI_ATTRS * ESI_ATTR_SIZE);
+ int ret, max_esi_attrs = CURR_MAX_ESI_ATTRS;
+ struct energy_scale_attribute *curr_esi;
+ struct h_energy_scale_info_hdr *hdr;
+ char *buf;
+
+ buf = kmalloc(esi_buf_size, GFP_KERNEL);
+ if (buf == NULL)
+ return -ENOMEM;
+
+retry:
+ ret = plpar_hcall_norets(H_GET_ENERGY_SCALE_INFO, ESI_FLAGS_SINGLE,
+ id, virt_to_phys(buf),
+ esi_buf_size);
+
+ /*
+ * If the hcall fails with not enough memory for either the
+ * header or data, attempt to allocate more
+ */
+ if (ret == H_PARTIAL || ret == H_P4) {
+ char *temp_buf;
+
+ max_esi_attrs += 4;
+ esi_buf_size = ESI_HDR_SIZE + (CURR_MAX_ESI_ATTRS * max_esi_attrs);
+
+ temp_buf = krealloc(buf, esi_buf_size, GFP_KERNEL);
+ if (temp_buf)
+ buf = temp_buf;
+ else
+ return -ENOMEM;
+
+ goto retry;
+ }
+
+ if (ret != H_SUCCESS) {
+ pr_warn("hcall failed: H_GET_ENERGY_SCALE_INFO");
+ ret = -EIO;
+ goto out_buf;
+ }
+
+ hdr = (struct h_energy_scale_info_hdr *) buf;
+ curr_esi = (struct energy_scale_attribute *)
+ (buf + be64_to_cpu(hdr->array_offset));
+
+ if (esi_buf_size <
+ be64_to_cpu(hdr->array_offset) + (be64_to_cpu(hdr->num_attrs)
+ * sizeof(struct energy_scale_attribute))) {
+ ret = -EIO;
+ goto out_buf;
+ }
+
+ *esi = *curr_esi;
+
+out_buf:
+ kfree(buf);
+
+ return ret;
+}
+
+/*
+ * Extract and export the description of the energy scale attributes
+ */
+static ssize_t desc_show(struct kobject *kobj,
+ struct kobj_attribute *kobj_attr,
+ char *buf)
+{
+ struct papr_attr *pattr = container_of(kobj_attr, struct papr_attr,
+ kobj_attr);
+ struct energy_scale_attribute esi;
+ int ret;
+
+ ret = papr_get_attr(pattr->id, &esi);
+ if (ret)
+ return ret;
+
+ return sysfs_emit(buf, "%s\n", esi.desc);
+}
+
+/*
+ * Extract and export the numeric value of the energy scale attributes
+ */
+static ssize_t val_show(struct kobject *kobj,
+ struct kobj_attribute *kobj_attr,
+ char *buf)
+{
+ struct papr_attr *pattr = container_of(kobj_attr, struct papr_attr,
+ kobj_attr);
+ struct energy_scale_attribute esi;
+ int ret;
+
+ ret = papr_get_attr(pattr->id, &esi);
+ if (ret)
+ return ret;
+
+ return sysfs_emit(buf, "%llu\n", be64_to_cpu(esi.val));
+}
+
+/*
+ * Extract and export the value description in string format of the energy
+ * scale attributes
+ */
+static ssize_t val_desc_show(struct kobject *kobj,
+ struct kobj_attribute *kobj_attr,
+ char *buf)
+{
+ struct papr_attr *pattr = container_of(kobj_attr, struct papr_attr,
+ kobj_attr);
+ struct energy_scale_attribute esi;
+ int ret;
+
+ ret = papr_get_attr(pattr->id, &esi);
+ if (ret)
+ return ret;
+
+ return sysfs_emit(buf, "%s\n", esi.value_desc);
+}
+
+static struct papr_ops_info {
+ const char *attr_name;
+ ssize_t (*show)(struct kobject *kobj, struct kobj_attribute *kobj_attr,
+ char *buf);
+} ops_info[KOBJ_MAX_ATTRS] = {
+ { "desc", desc_show },
+ { "value", val_show },
+ { "value_desc", val_desc_show },
+};
+
+static void add_attr(u64 id, int index, struct papr_attr *attr)
+{
+ attr->id = id;
+ sysfs_attr_init(&attr->kobj_attr.attr);
+ attr->kobj_attr.attr.name = ops_info[index].attr_name;
+ attr->kobj_attr.attr.mode = 0444;
+ attr->kobj_attr.show = ops_info[index].show;
+}
+
+static int add_attr_group(u64 id, struct papr_group *pg, bool show_val_desc)
+{
+ int i;
+
+ for (i = 0; i < KOBJ_MAX_ATTRS; i++) {
+ if (!strcmp(ops_info[i].attr_name, "value_desc") &&
+ !show_val_desc) {
+ continue;
+ }
+ add_attr(id, i, &pg->pgattrs[i]);
+ pg->pg.attrs[i] = &pg->pgattrs[i].kobj_attr.attr;
+ }
+
+ return sysfs_create_group(esi_kobj, &pg->pg);
+}
+
+
+static int __init papr_init(void)
+{
+ int esi_buf_size = ESI_HDR_SIZE + (CURR_MAX_ESI_ATTRS * ESI_ATTR_SIZE);
+ int ret, idx, i, max_esi_attrs = CURR_MAX_ESI_ATTRS;
+ struct h_energy_scale_info_hdr *esi_hdr;
+ struct energy_scale_attribute *esi_attrs;
+ uint64_t num_attrs;
+ char *esi_buf;
+
+ if (!firmware_has_feature(FW_FEATURE_LPAR) ||
+ !firmware_has_feature(FW_FEATURE_ENERGY_SCALE_INFO)) {
+ return -ENXIO;
+ }
+
+ esi_buf = kmalloc(esi_buf_size, GFP_KERNEL);
+ if (esi_buf == NULL)
+ return -ENOMEM;
+ /*
+ * hcall(
+ * uint64 H_GET_ENERGY_SCALE_INFO, // Get energy scale info
+ * uint64 flags, // Per the flag request
+ * uint64 firstAttributeId, // The attribute id
+ * uint64 bufferAddress, // Guest physical address of the output buffer
+ * uint64 bufferSize); // The size in bytes of the output buffer
+ */
+retry:
+
+ ret = plpar_hcall_norets(H_GET_ENERGY_SCALE_INFO, ESI_FLAGS_ALL, 0,
+ virt_to_phys(esi_buf), esi_buf_size);
+
+ /*
+ * If the hcall fails with not enough memory for either the
+ * header or data, attempt to allocate more
+ */
+ if (ret == H_PARTIAL || ret == H_P4) {
+ char *temp_esi_buf;
+
+ max_esi_attrs += 4;
+ esi_buf_size = ESI_HDR_SIZE + (CURR_MAX_ESI_ATTRS * max_esi_attrs);
+
+ temp_esi_buf = krealloc(esi_buf, esi_buf_size, GFP_KERNEL);
+ if (temp_esi_buf)
+ esi_buf = temp_esi_buf;
+ else
+ return -ENOMEM;
+
+ goto retry;
+ }
+
+ if (ret != H_SUCCESS) {
+ pr_warn("hcall failed: H_GET_ENERGY_SCALE_INFO, ret: %d\n", ret);
+ goto out_free_esi_buf;
+ }
+
+ esi_hdr = (struct h_energy_scale_info_hdr *) esi_buf;
+ num_attrs = be64_to_cpu(esi_hdr->num_attrs);
+ esi_attrs = (struct energy_scale_attribute *)
+ (esi_buf + be64_to_cpu(esi_hdr->array_offset));
+
+ if (esi_buf_size <
+ be64_to_cpu(esi_hdr->array_offset) +
+ (num_attrs * sizeof(struct energy_scale_attribute))) {
+ goto out_free_esi_buf;
+ }
+
+ papr_groups = kcalloc(num_attrs, sizeof(*papr_groups), GFP_KERNEL);
+ if (!papr_groups)
+ goto out_free_esi_buf;
+
+ papr_kobj = kobject_create_and_add("papr", firmware_kobj);
+ if (!papr_kobj) {
+ pr_warn("kobject_create_and_add papr failed\n");
+ goto out_papr_groups;
+ }
+
+ esi_kobj = kobject_create_and_add("energy_scale_info", papr_kobj);
+ if (!esi_kobj) {
+ pr_warn("kobject_create_and_add energy_scale_info failed\n");
+ goto out_kobj;
+ }
+
+ /* Allocate the groups before registering */
+ for (idx = 0; idx < num_attrs; idx++) {
+ papr_groups[idx].pg.attrs = kcalloc(KOBJ_MAX_ATTRS + 1,
+ sizeof(*papr_groups[idx].pg.attrs),
+ GFP_KERNEL);
+ if (!papr_groups[idx].pg.attrs)
+ goto out_pgattrs;
+
+ papr_groups[idx].pg.name = kasprintf(GFP_KERNEL, "%lld",
+ be64_to_cpu(esi_attrs[idx].id));
+ if (papr_groups[idx].pg.name == NULL)
+ goto out_pgattrs;
+ }
+
+ for (idx = 0; idx < num_attrs; idx++) {
+ bool show_val_desc = true;
+
+ /* Do not add the value desc attr if it does not exist */
+ if (strnlen(esi_attrs[idx].value_desc,
+ sizeof(esi_attrs[idx].value_desc)) == 0)
+ show_val_desc = false;
+
+ if (add_attr_group(be64_to_cpu(esi_attrs[idx].id),
+ &papr_groups[idx],
+ show_val_desc)) {
+ pr_warn("Failed to create papr attribute group %s\n",
+ papr_groups[idx].pg.name);
+ idx = num_attrs;
+ goto out_pgattrs;
+ }
+ }
+
+ kfree(esi_buf);
+ return 0;
+out_pgattrs:
+ for (i = 0; i < idx ; i++) {
+ kfree(papr_groups[i].pg.attrs);
+ kfree(papr_groups[i].pg.name);
+ }
+ kobject_put(esi_kobj);
+out_kobj:
+ kobject_put(papr_kobj);
+out_papr_groups:
+ kfree(papr_groups);
+out_free_esi_buf:
+ kfree(esi_buf);
+
+ return -ENOMEM;
+}
+
+machine_device_initcall(pseries, papr_init);
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