+#ifdef CONFIG_UCLAMP_TASK_GROUP
+static void cpu_util_update_eff(struct cgroup_subsys_state *css)
+{
+ struct cgroup_subsys_state *top_css = css;
+ struct uclamp_se *uc_parent = NULL;
+ struct uclamp_se *uc_se = NULL;
+ unsigned int eff[UCLAMP_CNT];
+ enum uclamp_id clamp_id;
+ unsigned int clamps;
+
+ css_for_each_descendant_pre(css, top_css) {
+ uc_parent = css_tg(css)->parent
+ ? css_tg(css)->parent->uclamp : NULL;
+
+ for_each_clamp_id(clamp_id) {
+ /* Assume effective clamps matches requested clamps */
+ eff[clamp_id] = css_tg(css)->uclamp_req[clamp_id].value;
+ /* Cap effective clamps with parent's effective clamps */
+ if (uc_parent &&
+ eff[clamp_id] > uc_parent[clamp_id].value) {
+ eff[clamp_id] = uc_parent[clamp_id].value;
+ }
+ }
+ /* Ensure protection is always capped by limit */
+ eff[UCLAMP_MIN] = min(eff[UCLAMP_MIN], eff[UCLAMP_MAX]);
+
+ /* Propagate most restrictive effective clamps */
+ clamps = 0x0;
+ uc_se = css_tg(css)->uclamp;
+ for_each_clamp_id(clamp_id) {
+ if (eff[clamp_id] == uc_se[clamp_id].value)
+ continue;
+ uc_se[clamp_id].value = eff[clamp_id];
+ uc_se[clamp_id].bucket_id = uclamp_bucket_id(eff[clamp_id]);
+ clamps |= (0x1 << clamp_id);
+ }
+ if (!clamps) {
+ css = css_rightmost_descendant(css);
+ continue;
+ }
+
+ /* Immediately update descendants RUNNABLE tasks */
+ uclamp_update_active_tasks(css, clamps);
+ }
+}
+
+/*
+ * Integer 10^N with a given N exponent by casting to integer the literal "1eN"
+ * C expression. Since there is no way to convert a macro argument (N) into a
+ * character constant, use two levels of macros.
+ */
+#define _POW10(exp) ((unsigned int)1e##exp)
+#define POW10(exp) _POW10(exp)
+
+struct uclamp_request {
+#define UCLAMP_PERCENT_SHIFT 2
+#define UCLAMP_PERCENT_SCALE (100 * POW10(UCLAMP_PERCENT_SHIFT))
+ s64 percent;
+ u64 util;
+ int ret;
+};
+
+static inline struct uclamp_request
+capacity_from_percent(char *buf)
+{
+ struct uclamp_request req = {
+ .percent = UCLAMP_PERCENT_SCALE,
+ .util = SCHED_CAPACITY_SCALE,
+ .ret = 0,
+ };
+
+ buf = strim(buf);
+ if (strcmp(buf, "max")) {
+ req.ret = cgroup_parse_float(buf, UCLAMP_PERCENT_SHIFT,
+ &req.percent);
+ if (req.ret)
+ return req;
+ if (req.percent > UCLAMP_PERCENT_SCALE) {
+ req.ret = -ERANGE;
+ return req;
+ }
+
+ req.util = req.percent << SCHED_CAPACITY_SHIFT;
+ req.util = DIV_ROUND_CLOSEST_ULL(req.util, UCLAMP_PERCENT_SCALE);
+ }
+
+ return req;
+}
+
+static ssize_t cpu_uclamp_write(struct kernfs_open_file *of, char *buf,
+ size_t nbytes, loff_t off,
+ enum uclamp_id clamp_id)
+{
+ struct uclamp_request req;
+ struct task_group *tg;
+
+ req = capacity_from_percent(buf);
+ if (req.ret)
+ return req.ret;
+
+ mutex_lock(&uclamp_mutex);
+ rcu_read_lock();
+
+ tg = css_tg(of_css(of));
+ if (tg->uclamp_req[clamp_id].value != req.util)
+ uclamp_se_set(&tg->uclamp_req[clamp_id], req.util, false);
+
+ /*
+ * Because of not recoverable conversion rounding we keep track of the
+ * exact requested value
+ */
+ tg->uclamp_pct[clamp_id] = req.percent;
+
+ /* Update effective clamps to track the most restrictive value */
+ cpu_util_update_eff(of_css(of));
+
+ rcu_read_unlock();
+ mutex_unlock(&uclamp_mutex);
+
+ return nbytes;
+}
+
+static ssize_t cpu_uclamp_min_write(struct kernfs_open_file *of,
+ char *buf, size_t nbytes,
+ loff_t off)
+{
+ return cpu_uclamp_write(of, buf, nbytes, off, UCLAMP_MIN);
+}
+
+static ssize_t cpu_uclamp_max_write(struct kernfs_open_file *of,
+ char *buf, size_t nbytes,
+ loff_t off)
+{
+ return cpu_uclamp_write(of, buf, nbytes, off, UCLAMP_MAX);
+}
+
+static inline void cpu_uclamp_print(struct seq_file *sf,
+ enum uclamp_id clamp_id)
+{
+ struct task_group *tg;
+ u64 util_clamp;
+ u64 percent;
+ u32 rem;
+
+ rcu_read_lock();
+ tg = css_tg(seq_css(sf));
+ util_clamp = tg->uclamp_req[clamp_id].value;
+ rcu_read_unlock();
+
+ if (util_clamp == SCHED_CAPACITY_SCALE) {
+ seq_puts(sf, "max\n");
+ return;
+ }
+
+ percent = tg->uclamp_pct[clamp_id];
+ percent = div_u64_rem(percent, POW10(UCLAMP_PERCENT_SHIFT), &rem);
+ seq_printf(sf, "%llu.%0*u\n", percent, UCLAMP_PERCENT_SHIFT, rem);
+}
+
+static int cpu_uclamp_min_show(struct seq_file *sf, void *v)
+{
+ cpu_uclamp_print(sf, UCLAMP_MIN);
+ return 0;
+}
+
+static int cpu_uclamp_max_show(struct seq_file *sf, void *v)
+{
+ cpu_uclamp_print(sf, UCLAMP_MAX);
+ return 0;
+}
+#endif /* CONFIG_UCLAMP_TASK_GROUP */
+