2012-09-20 20:03:42 +00:00
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/*
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* clk-divider.c - generic barebox clock support. Based on Linux clk support
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*
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* Copyright (c) 2012 Sascha Hauer <s.hauer@pengutronix.de>, Pengutronix
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of
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* the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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*/
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#include <common.h>
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#include <io.h>
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#include <malloc.h>
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#include <linux/clk.h>
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#include <linux/err.h>
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2014-03-13 09:04:46 +00:00
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#define div_mask(d) ((1 << ((d)->width)) - 1)
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static unsigned int _get_maxdiv(struct clk_divider *divider)
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2013-04-15 12:06:28 +00:00
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{
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2014-03-13 09:04:46 +00:00
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if (divider->flags & CLK_DIVIDER_ONE_BASED)
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return div_mask(divider);
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return div_mask(divider) + 1;
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2013-04-15 12:06:28 +00:00
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}
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2012-09-20 20:03:42 +00:00
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2014-03-13 09:04:46 +00:00
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static unsigned int _get_table_div(const struct clk_div_table *table,
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unsigned int val)
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{
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const struct clk_div_table *clkt;
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for (clkt = table; clkt->div; clkt++)
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if (clkt->val == val)
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return clkt->div;
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return 0;
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}
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static unsigned int _get_div(struct clk_divider *divider, unsigned int val)
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{
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if (divider->flags & CLK_DIVIDER_ONE_BASED)
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return val;
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if (divider->table)
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return _get_table_div(divider->table, val);
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return val + 1;
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}
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static unsigned int _get_table_val(const struct clk_div_table *table,
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unsigned int div)
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{
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const struct clk_div_table *clkt;
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for (clkt = table; clkt->div; clkt++)
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if (clkt->div == div)
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return clkt->val;
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return 0;
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}
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static unsigned int _get_val(struct clk_divider *divider, unsigned int div)
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{
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if (divider->flags & CLK_DIVIDER_ONE_BASED)
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return div;
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if (divider->table)
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return _get_table_val(divider->table, div);
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return div - 1;
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}
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static unsigned long clk_divider_recalc_rate(struct clk *clk,
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2012-09-20 20:03:42 +00:00
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unsigned long parent_rate)
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{
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2014-03-13 09:04:46 +00:00
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struct clk_divider *divider = container_of(clk, struct clk_divider, clk);
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unsigned int div, val;
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val = readl(divider->reg) >> divider->shift;
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val &= div_mask(divider);
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div = _get_div(divider, val);
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return parent_rate / div;
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}
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/*
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* The reverse of DIV_ROUND_UP: The maximum number which
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* divided by m is r
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*/
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#define MULT_ROUND_UP(r, m) ((r) * (m) + (m) - 1)
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static bool _is_valid_table_div(const struct clk_div_table *table,
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unsigned int div)
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{
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const struct clk_div_table *clkt;
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for (clkt = table; clkt->div; clkt++)
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if (clkt->div == div)
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return true;
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return false;
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}
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static bool _is_valid_div(struct clk_divider *divider, unsigned int div)
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{
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if (divider->table)
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return _is_valid_table_div(divider->table, div);
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return true;
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}
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static int clk_divider_bestdiv(struct clk *clk, unsigned long rate,
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unsigned long *best_parent_rate)
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{
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struct clk_divider *divider = container_of(clk, struct clk_divider, clk);
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int i, bestdiv = 0;
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unsigned long parent_rate, best = 0, now, maxdiv;
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unsigned long parent_rate_saved = *best_parent_rate;
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2012-09-20 20:03:42 +00:00
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if (!rate)
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rate = 1;
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2014-03-13 09:04:46 +00:00
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maxdiv = _get_maxdiv(divider);
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2012-09-20 20:03:42 +00:00
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2014-03-13 09:04:46 +00:00
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if (!(clk->flags & CLK_SET_RATE_PARENT)) {
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parent_rate = *best_parent_rate;
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bestdiv = DIV_ROUND_UP(parent_rate, rate);
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bestdiv = bestdiv == 0 ? 1 : bestdiv;
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bestdiv = bestdiv > maxdiv ? maxdiv : bestdiv;
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return bestdiv;
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}
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2012-09-20 20:03:42 +00:00
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2014-03-13 09:04:46 +00:00
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/*
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* The maximum divider we can use without overflowing
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* unsigned long in rate * i below
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*/
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maxdiv = min(ULONG_MAX / rate, maxdiv);
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for (i = 1; i <= maxdiv; i++) {
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if (!_is_valid_div(divider, i))
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continue;
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if (rate * i == parent_rate_saved) {
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/*
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* It's the most ideal case if the requested rate can be
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* divided from parent clock without needing to change
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* parent rate, so return the divider immediately.
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*/
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*best_parent_rate = parent_rate_saved;
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return i;
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}
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parent_rate = clk_round_rate(clk_get_parent(clk),
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MULT_ROUND_UP(rate, i));
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now = parent_rate / i;
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if (now <= rate && now > best) {
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bestdiv = i;
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best = now;
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*best_parent_rate = parent_rate;
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}
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}
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2012-09-20 20:03:42 +00:00
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2014-03-13 09:04:46 +00:00
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if (!bestdiv) {
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bestdiv = _get_maxdiv(divider);
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*best_parent_rate = clk_round_rate(clk_get_parent(clk), 1);
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}
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return bestdiv;
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2012-09-20 20:03:42 +00:00
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}
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2014-03-13 09:04:46 +00:00
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static long clk_divider_round_rate(struct clk *clk, unsigned long rate,
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unsigned long *parent_rate)
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2012-09-20 20:03:42 +00:00
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{
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2014-03-13 09:04:46 +00:00
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int div;
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2012-09-20 20:03:42 +00:00
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2014-03-13 09:04:46 +00:00
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div = clk_divider_bestdiv(clk, rate, parent_rate);
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2012-09-20 20:03:42 +00:00
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2014-03-13 09:04:46 +00:00
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return *parent_rate / div;
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}
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static int clk_divider_set_rate(struct clk *clk, unsigned long rate,
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unsigned long parent_rate)
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{
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struct clk_divider *divider = container_of(clk, struct clk_divider, clk);
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unsigned int div, value;
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u32 val;
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if (clk->flags & CLK_SET_RATE_PARENT) {
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unsigned long best_parent_rate = parent_rate;
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div = clk_divider_bestdiv(clk, rate, &best_parent_rate);
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clk_set_rate(clk_get_parent(clk), best_parent_rate);
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2013-04-15 12:06:28 +00:00
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} else {
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2014-03-13 09:04:46 +00:00
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div = parent_rate / rate;
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2013-04-15 12:06:28 +00:00
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}
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2012-09-20 20:03:42 +00:00
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2014-03-13 09:04:46 +00:00
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value = _get_val(divider, div);
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if (value > div_mask(divider))
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value = div_mask(divider);
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val = readl(divider->reg);
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val &= ~(div_mask(divider) << divider->shift);
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val |= value << divider->shift;
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writel(val, divider->reg);
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return 0;
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2012-09-20 20:03:42 +00:00
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}
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struct clk_ops clk_divider_ops = {
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.set_rate = clk_divider_set_rate,
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.recalc_rate = clk_divider_recalc_rate,
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2014-03-13 09:04:46 +00:00
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.round_rate = clk_divider_round_rate,
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2012-09-20 20:03:42 +00:00
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};
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struct clk *clk_divider(const char *name, const char *parent,
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2014-03-13 09:02:23 +00:00
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void __iomem *reg, u8 shift, u8 width, unsigned flags)
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2012-09-20 20:03:42 +00:00
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{
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struct clk_divider *div = xzalloc(sizeof(*div));
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int ret;
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div->shift = shift;
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div->reg = reg;
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div->width = width;
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div->parent = parent;
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div->clk.ops = &clk_divider_ops;
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div->clk.name = name;
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2014-03-13 09:02:23 +00:00
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div->clk.flags = flags;
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2012-09-20 20:03:42 +00:00
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div->clk.parent_names = &div->parent;
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div->clk.num_parents = 1;
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ret = clk_register(&div->clk);
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if (ret) {
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free(div);
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return ERR_PTR(ret);
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}
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return &div->clk;
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}
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2013-04-15 12:06:28 +00:00
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struct clk *clk_divider_one_based(const char *name, const char *parent,
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2014-03-13 09:02:23 +00:00
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void __iomem *reg, u8 shift, u8 width, unsigned flags)
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2013-04-15 12:06:28 +00:00
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{
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struct clk_divider *div;
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struct clk *clk;
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2014-03-13 09:02:23 +00:00
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clk = clk_divider(name, parent, reg, shift, width, flags);
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2013-04-15 12:06:28 +00:00
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if (IS_ERR(clk))
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return clk;
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div = container_of(clk, struct clk_divider, clk);
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div->flags |= CLK_DIVIDER_ONE_BASED;
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return clk;
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}
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2014-03-13 09:07:44 +00:00
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struct clk *clk_divider_table(const char *name,
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const char *parent, void __iomem *reg, u8 shift, u8 width,
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const struct clk_div_table *table, unsigned flags)
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{
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struct clk_divider *div = xzalloc(sizeof(*div));
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const struct clk_div_table *clkt;
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int ret, max_div = 0;
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div->shift = shift;
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div->reg = reg;
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div->width = width;
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div->parent = parent;
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div->clk.ops = &clk_divider_ops;
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div->clk.name = name;
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div->clk.flags = flags;
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div->clk.parent_names = &div->parent;
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div->clk.num_parents = 1;
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div->table = table;
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for (clkt = div->table; clkt->div; clkt++) {
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if (clkt->div > max_div) {
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max_div = clkt->div;
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div->max_div_index = div->table_size;
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}
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div->table_size++;
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}
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ret = clk_register(&div->clk);
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if (ret) {
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free(div);
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return ERR_PTR(ret);
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}
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return &div->clk;
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}
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