1 // SPDX-License-Identifier: GPL-2.0-only
4  * Copyright (c) 2024-2025 Haylen Chu <heylenay@4d2.org>
6  * DDN stands for "Divider Denominator Numerator", it's M/N clock with a
10  *	2 * ------------- = -------
16  *	Fout = ----- * -------------
20 #include <linux/clk-provider.h>
26 				       unsigned long den, unsigned int pre_div)  in ccu_ddn_calc_rate()  argument
28 	return prate * den / pre_div / num;  in ccu_ddn_calc_rate()
33 					    unsigned long *num, unsigned long *den)  in ccu_ddn_calc_best_rate()  argument
35 	rational_best_approximation(rate, prate / ddn->pre_div,  in ccu_ddn_calc_best_rate()
36 				    ddn->den_mask >> ddn->den_shift,  in ccu_ddn_calc_best_rate()
37 				    ddn->num_mask >> ddn->num_shift,  in ccu_ddn_calc_best_rate()
38 				    den, num);  in ccu_ddn_calc_best_rate()
39 	return ccu_ddn_calc_rate(prate, *num, *den, ddn->pre_div);  in ccu_ddn_calc_best_rate()
46 	unsigned long num, den;  in ccu_ddn_determine_rate()  local
48 	req->rate = ccu_ddn_calc_best_rate(ddn, req->rate,  in ccu_ddn_determine_rate()
49 					   req->best_parent_rate, &num, &den);  in ccu_ddn_determine_rate()
57 	unsigned int val, num, den;  in ccu_ddn_recalc_rate()  local
59 	val = ccu_read(&ddn->common, ctrl);  in ccu_ddn_recalc_rate()
61 	num = (val & ddn->num_mask) >> ddn->num_shift;  in ccu_ddn_recalc_rate()
62 	den = (val & ddn->den_mask) >> ddn->den_shift;  in ccu_ddn_recalc_rate()
64 	return ccu_ddn_calc_rate(prate, num, den, ddn->pre_div);  in ccu_ddn_recalc_rate()
71 	unsigned long num, den;  in ccu_ddn_set_rate()  local
73 	ccu_ddn_calc_best_rate(ddn, rate, prate, &num, &den);  in ccu_ddn_set_rate()
75 	ccu_update(&ddn->common, ctrl,  in ccu_ddn_set_rate()
76 		   ddn->num_mask | ddn->den_mask,  in ccu_ddn_set_rate()
77 		   (num << ddn->num_shift) | (den << ddn->den_shift));  in ccu_ddn_set_rate()