sound/soc/codecs/rl6231.c

Source file repositories/reference/linux-study-clean/sound/soc/codecs/rl6231.c

File Facts

System
Linux kernel
Corpus path
sound/soc/codecs/rl6231.c
Extension
.c
Size
5424 bytes
Lines
254
Domain
Driver Families
Bucket
sound/soc
Inferred role
Driver Families: exported/initcall integration point
Status
integration implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

struct pll_calc_map {
	unsigned int pll_in;
	unsigned int pll_out;
	int k;
	int n;
	int m;
	bool m_bp;
	bool k_bp;
};

static const struct pll_calc_map pll_preset_table[] = {
	{19200000,  4096000,  23, 14, 1, false, false},
	{19200000,  24576000,  3, 30, 3, false, false},
	{48000000,  3840000,  23,  2, 0, false, false},
	{3840000,   24576000,  3, 30, 0, true, false},
	{3840000,   22579200,  3,  5, 0, true, false},
};

static unsigned int find_best_div(unsigned int in,
	unsigned int max, unsigned int div)
{
	unsigned int d;

	if (in <= max)
		return 1;

	d = in / max;
	if (in % max)
		d++;

	while (div % d != 0)
		d++;


	return d;
}

/**
 * rl6231_pll_calc - Calcualte PLL M/N/K code.
 * @freq_in: external clock provided to codec.
 * @freq_out: target clock which codec works on.
 * @pll_code: Pointer to structure with M, N, K, m_bypass and k_bypass flag.
 *
 * Calcualte M/N/K code to configure PLL for codec.
 *
 * Returns 0 for success or negative error code.
 */
int rl6231_pll_calc(const unsigned int freq_in,
	const unsigned int freq_out, struct rl6231_pll_code *pll_code)
{
	int max_n = RL6231_PLL_N_MAX, max_m = RL6231_PLL_M_MAX;
	int i, k, n_t;
	int k_t, min_k, max_k, n = 0, m = 0, m_t = 0;
	unsigned int red, pll_out, in_t, out_t, div, div_t;
	unsigned int red_t = abs(freq_out - freq_in);
	unsigned int f_in, f_out, f_max;
	bool m_bypass = false, k_bypass = false;

	if (RL6231_PLL_INP_MAX < freq_in || RL6231_PLL_INP_MIN > freq_in)
		return -EINVAL;

	for (i = 0; i < ARRAY_SIZE(pll_preset_table); i++) {
		if (freq_in == pll_preset_table[i].pll_in &&
			freq_out == pll_preset_table[i].pll_out) {
			k = pll_preset_table[i].k;
			m = pll_preset_table[i].m;
			n = pll_preset_table[i].n;
			m_bypass = pll_preset_table[i].m_bp;
			k_bypass = pll_preset_table[i].k_bp;
			pr_debug("Use preset PLL parameter table\n");
			goto code_find;
		}
	}

	min_k = 80000000 / freq_out - 2;
	max_k = 150000000 / freq_out - 2;
	if (max_k > RL6231_PLL_K_MAX)
		max_k = RL6231_PLL_K_MAX;
	if (min_k > RL6231_PLL_K_MAX)
		min_k = max_k = RL6231_PLL_K_MAX;
	div_t = gcd(freq_in, freq_out);
	f_max = 0xffffffff / RL6231_PLL_N_MAX;
	div = find_best_div(freq_in, f_max, div_t);
	f_in = freq_in / div;
	f_out = freq_out / div;
	k = min_k;
	if (min_k < -1)
		min_k = -1;
	for (k_t = min_k; k_t <= max_k; k_t++) {
		for (n_t = 0; n_t <= max_n; n_t++) {

Annotation

Implementation Notes