1 // SPDX-License-Identifier: GPL-2.0-only
14 #include "aptina-pll.h"
25 	unsigned int div;  in aptina_pll_calculate()  local
27 	dev_dbg(dev, "PLL: ext clock %u pix clock %u\n",  in aptina_pll_calculate()
28 		pll->ext_clock, pll->pix_clock);  in aptina_pll_calculate()
30 	if (pll->ext_clock < limits->ext_clock_min ||  in aptina_pll_calculate()
31 	    pll->ext_clock > limits->ext_clock_max) {  in aptina_pll_calculate()
32 		dev_err(dev, "pll: invalid external clock frequency.\n");  in aptina_pll_calculate()
33 		return -EINVAL;  in aptina_pll_calculate()
36 	if (pll->pix_clock == 0 || pll->pix_clock > limits->pix_clock_max) {  in aptina_pll_calculate()
37 		dev_err(dev, "pll: invalid pixel clock frequency.\n");  in aptina_pll_calculate()
38 		return -EINVAL;  in aptina_pll_calculate()
42 	div = gcd(pll->pix_clock, pll->ext_clock);  in aptina_pll_calculate()
43 	pll->m = pll->pix_clock / div;  in aptina_pll_calculate()
44 	div = pll->ext_clock / div;  in aptina_pll_calculate()
47 	 * desired pixel clock frequency, but they might be out of the valid  in aptina_pll_calculate()
51 	 * - minimum/maximum multiplier  in aptina_pll_calculate()
52 	 * - minimum/maximum multiplier output clock frequency assuming the  in aptina_pll_calculate()
54 	 * - minimum/maximum combined N*P1 divisor  in aptina_pll_calculate()
56 	mf_min = DIV_ROUND_UP(limits->m_min, pll->m);  in aptina_pll_calculate()
57 	mf_min = max(mf_min, limits->out_clock_min /  in aptina_pll_calculate()
58 		     (pll->ext_clock / limits->n_min * pll->m));  in aptina_pll_calculate()
59 	mf_min = max(mf_min, limits->n_min * limits->p1_min / div);  in aptina_pll_calculate()
60 	mf_max = limits->m_max / pll->m;  in aptina_pll_calculate()
61 	mf_max = min(mf_max, limits->out_clock_max /  in aptina_pll_calculate()
62 		    (pll->ext_clock / limits->n_max * pll->m));  in aptina_pll_calculate()
63 	mf_max = min(mf_max, DIV_ROUND_UP(limits->n_max * limits->p1_max, div));  in aptina_pll_calculate()
68 		return -EINVAL;  in aptina_pll_calculate()
78 	 * 3. div * mf is a multiple of p1, in order to compute  in aptina_pll_calculate()
79 	 *	n = div * mf / p1  in aptina_pll_calculate()
80 	 *	m = pll->m * mf  in aptina_pll_calculate()
81 	 * 4. the internal clock frequency, given by ext_clock / n, is in the  in aptina_pll_calculate()
83 	 * 5. the output clock frequency, given by ext_clock / n * m, is in the  in aptina_pll_calculate()
95 	 *	mf_inc = p1 / gcd(div, p1)			(6)  in aptina_pll_calculate()
104 	 *	ext_clock / (div * mf / p1) * m * mf >= out_clock_min  in aptina_pll_calculate()
105 	 *	ext_clock / (div * mf / p1) * m * mf <= out_clock_max  in aptina_pll_calculate()
109 	 *	p1 >= out_clock_min * div / (ext_clock * m)	(7)  in aptina_pll_calculate()
110 	 *	p1 <= out_clock_max * div / (ext_clock * m)  in aptina_pll_calculate()
114 	 *	mf >= ext_clock * p1 / (int_clock_max * div)	(8)  in aptina_pll_calculate()
115 	 *	mf <= ext_clock * p1 / (int_clock_min * div)  in aptina_pll_calculate()
123 	if (limits->p1_min == 0) {  in aptina_pll_calculate()
125 		return -EINVAL;  in aptina_pll_calculate()
128 	p1_min = max(limits->p1_min, DIV_ROUND_UP(limits->out_clock_min * div,  in aptina_pll_calculate()
129 		     pll->ext_clock * pll->m));  in aptina_pll_calculate()
130 	p1_max = min(limits->p1_max, limits->out_clock_max * div /  in aptina_pll_calculate()
131 		     (pll->ext_clock * pll->m));  in aptina_pll_calculate()
133 	for (p1 = p1_max & ~1; p1 >= p1_min; p1 -= 2) {  in aptina_pll_calculate()
134 		unsigned int mf_inc = p1 / gcd(div, p1);  in aptina_pll_calculate()
138 		mf_low = roundup(max(mf_min, DIV_ROUND_UP(pll->ext_clock * p1,  in aptina_pll_calculate()
139 					limits->int_clock_max * div)), mf_inc);  in aptina_pll_calculate()
140 		mf_high = min(mf_max, pll->ext_clock * p1 /  in aptina_pll_calculate()
141 			      (limits->int_clock_min * div));  in aptina_pll_calculate()
146 		pll->n = div * mf_low / p1;  in aptina_pll_calculate()
147 		pll->m *= mf_low;  in aptina_pll_calculate()
148 		pll->p1 = p1;  in aptina_pll_calculate()
149 		dev_dbg(dev, "PLL: N %u M %u P1 %u\n", pll->n, pll->m, pll->p1);  in aptina_pll_calculate()
154 	return -EINVAL;  in aptina_pll_calculate()