U-Boot

// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (c) 2020, The Linux Foundation. All rights reserved.
 * Copyright (c) 2024 Qualcomm Innovation Center, Inc. All rights reserved.
 * Copyright (c) 2025 Linaro Limited
 */

#include <dm.h>
#include <log.h>
#include <malloc.h>
#include <linux/err.h>
#include <div64.h>
#include <dm/device_compat.h>
#include <linux/list_sort.h>

#include "bcm-voter.h"

/* TODO drop WAKE/SLEEP buckets fills if we really don't need them */

/**
 * struct bcm_voter - Bus Clock Manager voter
 * @dev: reference to the device that communicates with the BCM
 * @np: reference to the device node to match bcm voters
 * @commit_list: list containing bcms to be committed to hardware
 * @ws_list: list containing bcms that have different wake/sleep votes
 * @voter_node: list of bcm voters
 * @tcs_wait: mask for which buckets require TCS completion
 */
struct bcm_voter {
	struct udevice *dev;
	struct list_head commit_list;
	struct list_head ws_list;
	u32 tcs_wait;
};

static int cmp_vcd(void *priv, struct list_head *a, struct list_head *b)
{
	struct qcom_icc_bcm *bcm_a = list_entry(a, struct qcom_icc_bcm, list);
	struct qcom_icc_bcm *bcm_b = list_entry(b, struct qcom_icc_bcm, list);

	return bcm_a->aux_data.vcd - bcm_b->aux_data.vcd;
}

static u64 bcm_div(u64 num, u32 base)
{
	/* Ensure that small votes aren't lost. */
	if (num && num < base)
		return 1;

	do_div(num, base);

	return num;
}

/* BCMs with enable_mask use one-hot-encoding for on/off signaling */
static void bcm_aggregate_mask(struct qcom_icc_bcm *bcm)
{
	struct qcom_icc_node *node;
	int bucket, i;

	for (bucket = 0; bucket < QCOM_ICC_NUM_BUCKETS; bucket++) {
		bcm->vote_x[bucket] = 0;
		bcm->vote_y[bucket] = 0;

		for (i = 0; i < bcm->num_nodes; i++) {
			node = bcm->nodes[i];

			/* If any vote in this bucket exists, keep the BCM enabled */
			if (node->sum_avg[bucket] || node->max_peak[bucket]) {
				bcm->vote_x[bucket] = 0;
				bcm->vote_y[bucket] = bcm->enable_mask;
				break;
			}
		}
	}

	if (bcm->keepalive) {
		bcm->vote_x[QCOM_ICC_BUCKET_AMC] = bcm->enable_mask;
		bcm->vote_x[QCOM_ICC_BUCKET_WAKE] = bcm->enable_mask;
		bcm->vote_y[QCOM_ICC_BUCKET_AMC] = bcm->enable_mask;
		bcm->vote_y[QCOM_ICC_BUCKET_WAKE] = bcm->enable_mask;
	}
}

static void bcm_aggregate(struct qcom_icc_bcm *bcm)
{
	struct qcom_icc_node *node;
	size_t i, bucket;
	u64 agg_avg[QCOM_ICC_NUM_BUCKETS] = {0};
	u64 agg_peak[QCOM_ICC_NUM_BUCKETS] = {0};
	u64 temp;

	for (bucket = 0; bucket < QCOM_ICC_NUM_BUCKETS; bucket++) {
		for (i = 0; i < bcm->num_nodes; i++) {
			node = bcm->nodes[i];
			temp = bcm_div(node->sum_avg[bucket] * bcm->aux_data.width,
				       node->buswidth * node->channels);
			agg_avg[bucket] = max(agg_avg[bucket], temp);

			temp = bcm_div(node->max_peak[bucket] * bcm->aux_data.width,
				       node->buswidth);
			agg_peak[bucket] = max(agg_peak[bucket], temp);
		}

		temp = agg_avg[bucket] * bcm->vote_scale;
		bcm->vote_x[bucket] = bcm_div(temp, bcm->aux_data.unit);

		temp = agg_peak[bucket] * bcm->vote_scale;
		bcm->vote_y[bucket] = bcm_div(temp, bcm->aux_data.unit);
	}

	if (bcm->keepalive && bcm->vote_x[QCOM_ICC_BUCKET_AMC] == 0 &&
	    bcm->vote_y[QCOM_ICC_BUCKET_AMC] == 0) {
		bcm->vote_x[QCOM_ICC_BUCKET_AMC] = 1;
		bcm->vote_x[QCOM_ICC_BUCKET_WAKE] = 1;
		bcm->vote_y[QCOM_ICC_BUCKET_AMC] = 1;
		bcm->vote_y[QCOM_ICC_BUCKET_WAKE] = 1;
	}
}

static inline void tcs_cmd_gen(struct tcs_cmd *cmd, u64 vote_x, u64 vote_y,
			       u32 addr, bool commit, bool wait)
{
	bool valid = true;

	if (!cmd)
		return;

	memset(cmd, 0, sizeof(*cmd));

	if (vote_x == 0 && vote_y == 0)
		valid = false;

	if (vote_x > BCM_TCS_CMD_VOTE_MASK)
		vote_x = BCM_TCS_CMD_VOTE_MASK;

	if (vote_y > BCM_TCS_CMD_VOTE_MASK)
		vote_y = BCM_TCS_CMD_VOTE_MASK;

	cmd->addr = addr;
	cmd->data = BCM_TCS_CMD(commit, valid, vote_x, vote_y);

	/*
	 * Set the wait for completion flag on command that need to be completed
	 * before the next command.
	 */
	cmd->wait = wait;
}

static void tcs_list_gen(struct bcm_voter *voter, int bucket,
			 struct tcs_cmd tcs_list[MAX_VCD],
			 int n[MAX_VCD + 1])
{
	struct list_head *bcm_list = &voter->commit_list;
	struct qcom_icc_bcm *bcm;
	bool commit, wait;
	size_t idx = 0, batch = 0, cur_vcd_size = 0;

	memset(n, 0, sizeof(int) * (MAX_VCD + 1));

	list_for_each_entry(bcm, bcm_list, list) {
		commit = false;
		cur_vcd_size++;
		if ((list_is_last(&bcm->list, bcm_list)) ||
		    bcm->aux_data.vcd != list_next_entry(bcm, list)->aux_data.vcd) {
			commit = true;
			cur_vcd_size = 0;
		}

		wait = commit && (voter->tcs_wait & BIT(bucket));

		tcs_cmd_gen(&tcs_list[idx], bcm->vote_x[bucket],
			    bcm->vote_y[bucket], bcm->addr, commit, wait);
		idx++;
		n[batch]++;
		/*
		 * Batch the BCMs in such a way that we do not split them in
		 * multiple payloads when they are under the same VCD. This is
		 * to ensure that every BCM is committed since we only set the
		 * commit bit on the last BCM request of every VCD.
		 */
		if (n[batch] >= MAX_RPMH_PAYLOAD) {
			if (!commit) {
				n[batch] -= cur_vcd_size;
				n[batch + 1] = cur_vcd_size;
			}
			batch++;
		}
	}
}

/**
 * of_bcm_voter_get - gets a bcm voter handle from DT node
 * @dev: device pointer for the consumer device
 * @name: name for the bcm voter device
 *
 * This function will match a device_node pointer for the phandle
 * specified in the device DT and return a bcm_voter handle on success.
 *
 * Returns bcm_voter pointer or ERR_PTR() on error. EPROBE_DEFER is returned
 * when matching bcm voter is yet to be found.
 */
struct bcm_voter *of_bcm_voter_get(struct udevice *dev, const char *name)
{
	struct ofnode_phandle_args args;
	struct udevice *bcm_dev;
	int ret, idx = 0;

	if (name) {
		idx = dev_read_stringlist_search(dev, "qcom,bcm-voter-names", name);
		if (idx < 0)
			return ERR_PTR(idx);
	}

	ret = dev_read_phandle_with_args(dev, "qcom,bcm-voters", NULL, 0,
					 idx, &args);
	if (ret)
		return ERR_PTR(idx);

	ret = uclass_get_device_by_ofnode(UCLASS_MISC, args.node,
					  &bcm_dev);
	if (ret) {
		debug("%s: uclass_get_device_by_ofnode failed: %d\n",
		      __func__, ret);
		return ERR_PTR(ret);
	}

	return dev_get_priv(bcm_dev);
}

/**
 * qcom_icc_bcm_voter_add - queues up the bcm nodes that require updates
 * @voter: voter that the bcms are being added to
 * @bcm: bcm to add to the commit and wake sleep list
 */
void qcom_icc_bcm_voter_add(struct bcm_voter *voter, struct qcom_icc_bcm *bcm)
{
	if (!voter)
		return;

	if (list_empty(&bcm->list))
		list_add_tail(&bcm->list, &voter->commit_list);

	if (list_empty(&bcm->ws_list))
		list_add_tail(&bcm->ws_list, &voter->ws_list);
}

/**
 * qcom_icc_bcm_voter_commit - generates and commits tcs cmds based on bcms
 * @voter: voter that needs flushing
 *
 * This function generates a set of AMC commands and flushes to the BCM device
 * associated with the voter. It conditionally generate WAKE and SLEEP commands
 * based on deltas between WAKE/SLEEP requirements. The ws_list persists
 * through multiple commit requests and bcm nodes are removed only when the
 * requirements for WAKE matches SLEEP.
 *
 * Returns 0 on success, or an appropriate error code otherwise.
 */
int qcom_icc_bcm_voter_commit(struct bcm_voter *voter)
{
	struct qcom_icc_bcm *bcm;
	struct qcom_icc_bcm *bcm_tmp;
	int commit_idx[MAX_VCD + 1];
	struct tcs_cmd cmds[MAX_BCMS];
	int ret = 0;

	if (!voter)
		return 0;

	list_for_each_entry(bcm, &voter->commit_list, list) {
		if (bcm->enable_mask)
			bcm_aggregate_mask(bcm);
		else
			bcm_aggregate(bcm);
	}

	/*
	 * Pre sort the BCMs based on VCD for ease of generating a command list
	 * that groups the BCMs with the same VCD together. VCDs are numbered
	 * with lowest being the most expensive time wise, ensuring that
	 * those commands are being sent the earliest in the queue. This needs
	 * to be sorted every commit since we can't guarantee the order in which
	 * the BCMs are added to the list.
	 */
	list_sort(NULL, &voter->commit_list, cmp_vcd);

	/*
	 * Construct the command list based on a pre ordered list of BCMs
	 * based on VCD.
	 */
	tcs_list_gen(voter, QCOM_ICC_BUCKET_AMC, cmds, commit_idx);
	if (!commit_idx[0])
		goto out;

	for (int i = 0 ; commit_idx[i] ; ++i) {
		ret = rpmh_write(voter->dev, RPMH_ACTIVE_ONLY_STATE,
				 &cmds[i], commit_idx[i]);
		if (ret) {
			pr_err("Error sending AMC RPMH requests (%d)\n", ret);
			goto out;
		}
	}

	/* TOFIX vote for WAKE & SLEEP ?? */

out:
	list_for_each_entry_safe(bcm, bcm_tmp, &voter->commit_list, list)
		list_del_init(&bcm->list);

	return ret;
}

static int qcom_icc_bcm_voter_probe(struct udevice *dev)
{
	struct bcm_voter *voter = dev_get_priv(dev);

	voter->dev = dev;

	if (dev_read_u32(dev, "qcom,tcs-wait", &voter->tcs_wait))
		voter->tcs_wait = QCOM_ICC_TAG_ACTIVE_ONLY;

	INIT_LIST_HEAD(&voter->commit_list);
	INIT_LIST_HEAD(&voter->ws_list);

	return 0;
}

static const struct udevice_id qcom_icc_bcm_voter_ids[] = {
	{ .compatible = "qcom,bcm-voter" },
	{ }
};

U_BOOT_DRIVER(qcom_icc_bcm_voter) = {
	.name		= "qcom_bcm_voter",
	.id		= UCLASS_MISC,
	.priv_auto	= sizeof(struct bcm_voter),
	.probe		= qcom_icc_bcm_voter_probe,
	.of_match	= qcom_icc_bcm_voter_ids,
};