1 /* $NetBSD: imx_ccm_div.c,v 1.1 2020/12/23 14:42:38 skrll Exp $ */ 2 3 /*- 4 * Copyright (c) 2020 Jared McNeill <jmcneill@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: imx_ccm_div.c,v 1.1 2020/12/23 14:42:38 skrll Exp $"); 31 32 #include <sys/param.h> 33 #include <sys/bus.h> 34 35 #include <dev/clk/clk_backend.h> 36 37 #include <arm/nxp/imx_ccm.h> 38 39 #include <dev/fdt/fdtvar.h> 40 41 u_int 42 imx_ccm_div_get_rate(struct imx_ccm_softc *sc, 43 struct imx_ccm_clk *clk) 44 { 45 struct imx_ccm_div *div = &clk->u.div; 46 struct clk *clkp, *clkp_parent; 47 48 KASSERT(clk->type == IMX_CCM_DIV); 49 50 clkp = &clk->base; 51 clkp_parent = clk_get_parent(clkp); 52 if (clkp_parent == NULL) 53 return 0; 54 55 const u_int prate = clk_get_rate(clkp_parent); 56 if (prate == 0) 57 return 0; 58 59 const uint32_t val = CCM_READ(sc, clk->regidx, div->reg); 60 const u_int n = __SHIFTOUT(val, div->mask); 61 62 return prate / (n + 1); 63 } 64 65 int 66 imx_ccm_div_set_rate(struct imx_ccm_softc *sc, 67 struct imx_ccm_clk *clk, u_int rate) 68 { 69 struct imx_ccm_div *div = &clk->u.div; 70 struct clk *clkp, *clkp_parent; 71 int best_diff = INT_MAX; 72 u_int n, best_n; 73 uint32_t val; 74 75 KASSERT(clk->type == IMX_CCM_DIV); 76 77 clkp = &clk->base; 78 clkp_parent = clk_get_parent(clkp); 79 if (clkp_parent == NULL) 80 return ENXIO; 81 82 if ((div->flags & IMX_DIV_SET_RATE_PARENT) != 0) 83 return clk_set_rate(clkp, rate); 84 85 const u_int prate = clk_get_rate(clkp_parent); 86 if (prate == 0) 87 return EIO; 88 89 for (n = 0; n < __SHIFTOUT_MASK(div->mask); n++) { 90 const u_int tmp_rate = prate / (n + 1); 91 const int diff = (int)rate - (int)tmp_rate; 92 if ((div->flags & IMX_DIV_ROUND_DOWN) != 0) { 93 if (diff >= 0 && diff < best_diff) { 94 best_n = n; 95 best_diff = diff; 96 } 97 } else { 98 if (abs(diff) < abs(best_diff)) { 99 best_n = n; 100 best_diff = abs(diff); 101 } 102 } 103 } 104 if (best_diff == INT_MAX) 105 return EIO; 106 107 val = CCM_READ(sc, clk->regidx, div->reg); 108 val &= ~div->mask; 109 val |= __SHIFTIN(best_n, div->mask); 110 CCM_WRITE(sc, clk->regidx, div->reg, val); 111 112 return 0; 113 } 114 115 const char * 116 imx_ccm_div_get_parent(struct imx_ccm_softc *sc, 117 struct imx_ccm_clk *clk) 118 { 119 struct imx_ccm_div *div = &clk->u.div; 120 121 KASSERT(clk->type == IMX_CCM_DIV); 122 123 return div->parent; 124 } 125