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meson_clk_div.c revision 1.1 
      1 /* $NetBSD: meson_clk_div.c,v 1.1 2019/01/19 20:56:03 jmcneill Exp $ */
      2 
      3 /*-
      4  * Copyright (c) 2017-2019 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: meson_clk_div.c,v 1.1 2019/01/19 20:56:03 jmcneill Exp $");
     31 
     32 #include <sys/param.h>
     33 #include <sys/bus.h>
     34 
     35 #include <dev/clk/clk_backend.h>
     36 
     37 #include <arm/amlogic/meson_clk.h>
     38 
     39 u_int
     40 meson_clk_div_get_rate(struct meson_clk_softc *sc,
     41     struct meson_clk_clk *clk)
     42 {
     43 	struct meson_clk_div *div = &clk->u.div;
     44 	struct clk *clkp, *clkp_parent;
     45 	u_int rate, ratio;
     46 	uint32_t val;
     47 
     48 	KASSERT(clk->type == MESON_CLK_DIV);
     49 
     50 	clkp = &clk->base;
     51 	clkp_parent = clk_get_parent(clkp);
     52 	if (clkp_parent == NULL)
     53 		return 0;
     54 
     55 	rate = clk_get_rate(clkp_parent);
     56 	if (rate == 0)
     57 		return 0;
     58 
     59 	val = CLK_READ(sc, div->reg);
     60 	if (div->div)
     61 		ratio = __SHIFTOUT(val, div->div);
     62 	else
     63 		ratio = 0;
     64 
     65 	if (div->flags & MESON_CLK_DIV_POWER_OF_TWO) {
     66 		return rate >> ratio;
     67 	} else if (div->flags & MESON_CLK_DIV_CPU_SCALE_TABLE) {
     68 		if (ratio < 1 || ratio > 8)
     69 			return 0;
     70 		return rate / ((ratio + 1) * 2);
     71 	} else {
     72 		return rate / (ratio + 1);
     73 	}
     74 }
     75 
     76 int
     77 meson_clk_div_set_rate(struct meson_clk_softc *sc,
     78     struct meson_clk_clk *clk, u_int new_rate)
     79 {
     80 	struct meson_clk_div *div = &clk->u.div;
     81 	struct clk *clkp, *clkp_parent;
     82 	int parent_rate;
     83 	uint32_t val, raw_div;
     84 	int ratio;
     85 
     86 	KASSERT(clk->type == MESON_CLK_DIV);
     87 
     88 	clkp = &clk->base;
     89 	clkp_parent = clk_get_parent(clkp);
     90 	if (clkp_parent == NULL)
     91 		return ENXIO;
     92 
     93 	if (div->div == 0) {
     94 		if ((div->flags & MESON_CLK_DIV_SET_RATE_PARENT) != 0)
     95 			return clk_set_rate(clkp_parent, new_rate);
     96 		else
     97 			return ENXIO;
     98 	}
     99 
    100 	val = CLK_READ(sc, div->reg);
    101 
    102 	parent_rate = clk_get_rate(clkp_parent);
    103 	if (parent_rate == 0)
    104 		return (new_rate == 0) ? 0 : ERANGE;
    105 
    106 	ratio = howmany(parent_rate, new_rate);
    107 	if ((div->flags & MESON_CLK_DIV_POWER_OF_TWO) != 0) {
    108 		return EINVAL;
    109 	} else if ((div->flags & MESON_CLK_DIV_CPU_SCALE_TABLE) != 0) {
    110 		return EINVAL;
    111 	} else {
    112 		raw_div = (ratio > 0) ? ratio - 1 : 0;
    113 	}
    114 	if (raw_div > __SHIFTOUT_MASK(div->div))
    115 		return ERANGE;
    116 
    117 	val &= ~div->div;
    118 	val |= __SHIFTIN(raw_div, div->div);
    119 	CLK_WRITE(sc, div->reg, val);
    120 
    121 	return 0;
    122 }
    123 
    124 const char *
    125 meson_clk_div_get_parent(struct meson_clk_softc *sc,
    126     struct meson_clk_clk *clk)
    127 {
    128 	struct meson_clk_div *div = &clk->u.div;
    129 
    130 	KASSERT(clk->type == MESON_CLK_DIV);
    131 
    132 	return div->parent;
    133 }
    134