xref: /openbmc/linux/drivers/clk/spear/clk.c (revision 275876e2)
1 /*
2  * Copyright (C) 2012 ST Microelectronics
3  * Viresh Kumar <viresh.linux@gmail.com>
4  *
5  * This file is licensed under the terms of the GNU General Public
6  * License version 2. This program is licensed "as is" without any
7  * warranty of any kind, whether express or implied.
8  *
9  * SPEAr clk - Common routines
10  */
11 
12 #include <linux/clk-provider.h>
13 #include <linux/types.h>
14 #include "clk.h"
15 
16 long clk_round_rate_index(struct clk_hw *hw, unsigned long drate,
17 		unsigned long parent_rate, clk_calc_rate calc_rate, u8 rtbl_cnt,
18 		int *index)
19 {
20 	unsigned long prev_rate, rate = 0;
21 
22 	for (*index = 0; *index < rtbl_cnt; (*index)++) {
23 		prev_rate = rate;
24 		rate = calc_rate(hw, parent_rate, *index);
25 		if (drate < rate) {
26 			/* previous clock was best */
27 			if (*index) {
28 				rate = prev_rate;
29 				(*index)--;
30 			}
31 			break;
32 		}
33 	}
34 
35 	if ((*index) == rtbl_cnt)
36 		(*index)--;
37 
38 	return rate;
39 }
40