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sunxi_ccu_fractional.c revision 1.1 
      1 /* $NetBSD: sunxi_ccu_fractional.c,v 1.1 2018/03/19 16:18:30 bouyer Exp $ */
      2 
      3 /*-
      4  * Copyright (c) 2017 Jared McNeill <jmcneill (at) invisible.ca>
      5  * All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  *
     16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     17  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     18  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     19  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     20  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
     21  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
     22  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
     23  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
     24  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     26  * SUCH DAMAGE.
     27  */
     28 
     29 #include <sys/cdefs.h>
     30 __KERNEL_RCSID(0, "$NetBSD: sunxi_ccu_fractional.c,v 1.1 2018/03/19 16:18:30 bouyer Exp $");
     31 
     32 #include <sys/param.h>
     33 #include <sys/bus.h>
     34 
     35 #include <dev/clk/clk_backend.h>
     36 
     37 #include <arm/sunxi/sunxi_ccu.h>
     38 
     39 int
     40 sunxi_ccu_fractional_enable(struct sunxi_ccu_softc *sc,
     41     struct sunxi_ccu_clk *clk, int enable)
     42 {
     43 	struct sunxi_ccu_fractional *fractional = &clk->u.fractional;
     44 	uint32_t val;
     45 
     46 	KASSERT(clk->type == SUNXI_CCU_FRACTIONAL);
     47 
     48 	if (!fractional->enable)
     49 		return enable ? 0 : EINVAL;
     50 
     51 	val = CCU_READ(sc, fractional->reg);
     52 	if (enable)
     53 		val |= fractional->enable;
     54 	else
     55 		val &= ~fractional->enable;
     56 	CCU_WRITE(sc, fractional->reg, val);
     57 
     58 	return 0;
     59 }
     60 
     61 u_int
     62 sunxi_ccu_fractional_get_rate(struct sunxi_ccu_softc *sc,
     63     struct sunxi_ccu_clk *clk)
     64 {
     65 	struct sunxi_ccu_fractional *fractional = &clk->u.fractional;
     66 	struct clk *clkp, *clkp_parent;
     67 	u_int rate, m;
     68 	uint32_t val;
     69 
     70 	KASSERT(clk->type == SUNXI_CCU_FRACTIONAL);
     71 
     72 	clkp = &clk->base;
     73 	clkp_parent = clk_get_parent(clkp);
     74 	if (clkp_parent == NULL)
     75 		return 0;
     76 
     77 	rate = clk_get_rate(clkp_parent);
     78 	if (rate == 0)
     79 		return 0;
     80 
     81 	if (fractional->prediv > 0)
     82 		rate = rate / fractional->prediv;
     83 
     84 	val = CCU_READ(sc, fractional->reg);
     85 
     86 	if (fractional->enable && !(val & fractional->enable))
     87 		return 0;
     88 
     89 	if (val & fractional->frac_en) {
     90 		int sel = __SHIFTOUT(val, fractional->frac_sel);
     91 		return fractional->frac[sel];
     92 	}
     93 	m = __SHIFTOUT(val, fractional->m);
     94 
     95 	return rate * m;
     96 }
     97 
     98 int
     99 sunxi_ccu_fractional_set_rate(struct sunxi_ccu_softc *sc,
    100     struct sunxi_ccu_clk *clk, u_int new_rate)
    101 {
    102 	struct sunxi_ccu_fractional *fractional = &clk->u.fractional;
    103 	struct clk *clkp, *clkp_parent;
    104 	u_int parent_rate, best_rate, best_m;
    105 	u_int m, rate;
    106 	int best_diff;
    107 	uint32_t val;
    108 	int i;
    109 
    110 	clkp = &clk->base;
    111 	clkp_parent = clk_get_parent(clkp);
    112 	if (clkp_parent == NULL)
    113 		return ENXIO;
    114 
    115 	parent_rate = clk_get_rate(clkp_parent);
    116 	if (parent_rate == 0)
    117 		return (new_rate == 0) ? 0 : ERANGE;
    118 
    119 	if (fractional->prediv > 0)
    120 		parent_rate = parent_rate / fractional->prediv;
    121 
    122 	val = CCU_READ(sc, fractional->reg);
    123 	for (i = 0; i < __arraycount(fractional->frac); i++) {
    124 		if (fractional->frac[i] == new_rate) {
    125 			val |= fractional->frac_en;
    126 			val &= ~fractional->frac_sel;
    127 			val |= __SHIFTIN(i, fractional->frac_sel);
    128 			CCU_WRITE(sc, fractional->reg, val);
    129 			return 0;
    130 		}
    131 	}
    132 	val &= ~fractional->frac_en;
    133 
    134 	best_rate = 0;
    135 	best_diff = INT_MAX;
    136 
    137 	for (m = fractional->m_min; m <= fractional->m_max; m++) {
    138 		rate = parent_rate * m;
    139 		const int diff = abs(new_rate - rate);
    140 		if (diff < best_diff) {
    141 			best_diff = diff;
    142 			best_rate = rate;
    143 			best_m = m;
    144 		}
    145 	}
    146 
    147 	if (best_rate == 0)
    148 		return ERANGE;
    149 
    150 	val &= ~fractional->m;
    151 	val |= __SHIFTIN(best_m, fractional->m);
    152 	CCU_WRITE(sc, fractional->reg, val);
    153 
    154 	return 0;
    155 }
    156 
    157 const char *
    158 sunxi_ccu_fractional_get_parent(struct sunxi_ccu_softc *sc,
    159     struct sunxi_ccu_clk *clk)
    160 {
    161 	struct sunxi_ccu_fractional *fractional = &clk->u.fractional;
    162 
    163 	KASSERT(clk->type == SUNXI_CCU_FRACTIONAL);
    164 
    165 	return fractional->parent;
    166 }
    167