1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * Shared helper functions for devices from the ADAU family
4  *
5  * Copyright 2011-2016 Analog Devices Inc.
6  * Author: Lars-Peter Clausen <lars@metafoo.de>
7  */
8 
9 #include <linux/gcd.h>
10 #include <linux/kernel.h>
11 #include <linux/module.h>
12 
13 #include "adau-utils.h"
14 
adau_calc_pll_cfg(unsigned int freq_in,unsigned int freq_out,uint8_t regs[5])15 int adau_calc_pll_cfg(unsigned int freq_in, unsigned int freq_out,
16 	uint8_t regs[5])
17 {
18 	unsigned int r, n, m, i, j;
19 	unsigned int div;
20 
21 	if (!freq_out) {
22 		r = 0;
23 		n = 0;
24 		m = 0;
25 		div = 0;
26 	} else {
27 		if (freq_out % freq_in != 0) {
28 			div = DIV_ROUND_UP(freq_in, 13500000);
29 			freq_in /= div;
30 			r = freq_out / freq_in;
31 			i = freq_out % freq_in;
32 			j = gcd(i, freq_in);
33 			n = i / j;
34 			m = freq_in / j;
35 			div--;
36 		} else {
37 			r = freq_out / freq_in;
38 			n = 0;
39 			m = 0;
40 			div = 0;
41 		}
42 		if (n > 0xffff || m > 0xffff || div > 3 || r > 8 || r < 2)
43 			return -EINVAL;
44 	}
45 
46 	regs[0] = m >> 8;
47 	regs[1] = m & 0xff;
48 	regs[2] = n >> 8;
49 	regs[3] = n & 0xff;
50 	regs[4] = (r << 3) | (div << 1);
51 	if (m != 0)
52 		regs[4] |= 1; /* Fractional mode */
53 
54 	return 0;
55 }
56 EXPORT_SYMBOL_GPL(adau_calc_pll_cfg);
57 
58 MODULE_DESCRIPTION("ASoC ADAU audio CODECs shared helper functions");
59 MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
60 MODULE_LICENSE("GPL v2");
61