125 lines
3.4 KiB
C
125 lines
3.4 KiB
C
/* $NetBSD: imx_ccm_div.c,v 1.1 2020/12/23 14:42:38 skrll Exp $ */
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/*-
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* Copyright (c) 2020 Jared McNeill <jmcneill@invisible.ca>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__KERNEL_RCSID(0, "$NetBSD: imx_ccm_div.c,v 1.1 2020/12/23 14:42:38 skrll Exp $");
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#include <sys/param.h>
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#include <sys/bus.h>
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#include <dev/clk/clk_backend.h>
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#include <arm/nxp/imx_ccm.h>
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#include <dev/fdt/fdtvar.h>
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u_int
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imx_ccm_div_get_rate(struct imx_ccm_softc *sc,
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struct imx_ccm_clk *clk)
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{
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struct imx_ccm_div *div = &clk->u.div;
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struct clk *clkp, *clkp_parent;
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KASSERT(clk->type == IMX_CCM_DIV);
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clkp = &clk->base;
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clkp_parent = clk_get_parent(clkp);
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if (clkp_parent == NULL)
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return 0;
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const u_int prate = clk_get_rate(clkp_parent);
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if (prate == 0)
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return 0;
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const uint32_t val = CCM_READ(sc, clk->regidx, div->reg);
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const u_int n = __SHIFTOUT(val, div->mask);
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return prate / (n + 1);
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}
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int
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imx_ccm_div_set_rate(struct imx_ccm_softc *sc,
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struct imx_ccm_clk *clk, u_int rate)
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{
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struct imx_ccm_div *div = &clk->u.div;
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struct clk *clkp, *clkp_parent;
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int best_diff = INT_MAX;
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u_int n, best_n;
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uint32_t val;
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KASSERT(clk->type == IMX_CCM_DIV);
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clkp = &clk->base;
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clkp_parent = clk_get_parent(clkp);
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if (clkp_parent == NULL)
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return ENXIO;
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if ((div->flags & IMX_DIV_SET_RATE_PARENT) != 0)
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return clk_set_rate(clkp, rate);
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const u_int prate = clk_get_rate(clkp_parent);
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if (prate == 0)
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return EIO;
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for (n = 0; n < __SHIFTOUT_MASK(div->mask); n++) {
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const u_int tmp_rate = prate / (n + 1);
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const int diff = (int)rate - (int)tmp_rate;
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if ((div->flags & IMX_DIV_ROUND_DOWN) != 0) {
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if (diff >= 0 && diff < best_diff) {
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best_n = n;
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best_diff = diff;
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}
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} else {
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if (abs(diff) < abs(best_diff)) {
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best_n = n;
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best_diff = abs(diff);
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}
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}
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}
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if (best_diff == INT_MAX)
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return EIO;
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val = CCM_READ(sc, clk->regidx, div->reg);
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val &= ~div->mask;
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val |= __SHIFTIN(best_n, div->mask);
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CCM_WRITE(sc, clk->regidx, div->reg, val);
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return 0;
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}
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const char *
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imx_ccm_div_get_parent(struct imx_ccm_softc *sc,
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struct imx_ccm_clk *clk)
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{
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struct imx_ccm_div *div = &clk->u.div;
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KASSERT(clk->type == IMX_CCM_DIV);
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return div->parent;
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}
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