fe52e7505f
Commit 1d9fe6b97 ("clk: divider: Fix best div calculation for power-of-two and table dividers") introduces a regression in its _table_round_up function. When the divider passed to this function is greater than the max divider available in the table, this function returns table's max divider. Problem is that it causes an infinite loop in clk_divider_bestdiv() because _next_div() will never return a value greater than maxdiv. Instead of returning table's max divider, this patch returns INT_MAX. Reported-by: Fabio Estevam <festevam@gmail.com> Reported-by: Shawn Guo <shawn.guo@freescale.com> Tested-by: Fabio Estevam <festevam@gmail.com> Tested-by: Shawn Guo <shawn.guo@freescale.com> Signed-off-by: Maxime Coquelin <maxime.coquelin@st.com> Signed-off-by: Mike Turquette <mturquette@linaro.org>
381 lines
9.9 KiB
C
381 lines
9.9 KiB
C
/*
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* Copyright (C) 2011 Sascha Hauer, Pengutronix <s.hauer@pengutronix.de>
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* Copyright (C) 2011 Richard Zhao, Linaro <richard.zhao@linaro.org>
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* Copyright (C) 2011-2012 Mike Turquette, Linaro Ltd <mturquette@linaro.org>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* Adjustable divider clock implementation
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*/
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#include <linux/clk-provider.h>
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/io.h>
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#include <linux/err.h>
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#include <linux/string.h>
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#include <linux/log2.h>
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/*
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* DOC: basic adjustable divider clock that cannot gate
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*
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* Traits of this clock:
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* prepare - clk_prepare only ensures that parents are prepared
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* enable - clk_enable only ensures that parents are enabled
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* rate - rate is adjustable. clk->rate = DIV_ROUND_UP(parent->rate / divisor)
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* parent - fixed parent. No clk_set_parent support
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*/
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#define to_clk_divider(_hw) container_of(_hw, struct clk_divider, hw)
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#define div_mask(d) ((1 << ((d)->width)) - 1)
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static unsigned int _get_table_maxdiv(const struct clk_div_table *table)
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{
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unsigned int maxdiv = 0;
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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 > maxdiv)
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maxdiv = clkt->div;
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return maxdiv;
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}
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static unsigned int _get_maxdiv(struct clk_divider *divider)
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{
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if (divider->flags & CLK_DIVIDER_ONE_BASED)
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return div_mask(divider);
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if (divider->flags & CLK_DIVIDER_POWER_OF_TWO)
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return 1 << div_mask(divider);
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if (divider->table)
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return _get_table_maxdiv(divider->table);
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return div_mask(divider) + 1;
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}
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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->flags & CLK_DIVIDER_POWER_OF_TWO)
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return 1 << 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->flags & CLK_DIVIDER_POWER_OF_TWO)
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return __ffs(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_hw *hw,
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unsigned long parent_rate)
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{
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struct clk_divider *divider = to_clk_divider(hw);
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unsigned int div, val;
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val = clk_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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if (!div) {
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WARN(!(divider->flags & CLK_DIVIDER_ALLOW_ZERO),
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"%s: Zero divisor and CLK_DIVIDER_ALLOW_ZERO not set\n",
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__clk_get_name(hw->clk));
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return parent_rate;
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}
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return DIV_ROUND_UP(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->flags & CLK_DIVIDER_POWER_OF_TWO)
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return is_power_of_2(div);
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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 _round_up_table(const struct clk_div_table *table, int div)
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{
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const struct clk_div_table *clkt;
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int up = INT_MAX;
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for (clkt = table; clkt->div; clkt++) {
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if (clkt->div == div)
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return clkt->div;
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else if (clkt->div < div)
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continue;
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if ((clkt->div - div) < (up - div))
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up = clkt->div;
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}
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return up;
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}
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static int _div_round_up(struct clk_divider *divider,
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unsigned long parent_rate, unsigned long rate)
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{
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int div = DIV_ROUND_UP(parent_rate, rate);
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if (divider->flags & CLK_DIVIDER_POWER_OF_TWO)
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div = __roundup_pow_of_two(div);
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if (divider->table)
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div = _round_up_table(divider->table, div);
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return div;
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}
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static int clk_divider_bestdiv(struct clk_hw *hw, unsigned long rate,
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unsigned long *best_parent_rate)
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{
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struct clk_divider *divider = to_clk_divider(hw);
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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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if (!rate)
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rate = 1;
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maxdiv = _get_maxdiv(divider);
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if (!(__clk_get_flags(hw->clk) & CLK_SET_RATE_PARENT)) {
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parent_rate = *best_parent_rate;
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bestdiv = _div_round_up(divider, 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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/*
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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(hw->clk),
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MULT_ROUND_UP(rate, i));
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now = DIV_ROUND_UP(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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if (!bestdiv) {
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bestdiv = _get_maxdiv(divider);
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*best_parent_rate = __clk_round_rate(__clk_get_parent(hw->clk), 1);
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}
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return bestdiv;
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}
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static long clk_divider_round_rate(struct clk_hw *hw, unsigned long rate,
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unsigned long *prate)
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{
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int div;
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div = clk_divider_bestdiv(hw, rate, prate);
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return DIV_ROUND_UP(*prate, div);
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}
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static int clk_divider_set_rate(struct clk_hw *hw, unsigned long rate,
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unsigned long parent_rate)
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{
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struct clk_divider *divider = to_clk_divider(hw);
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unsigned int div, value;
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unsigned long flags = 0;
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u32 val;
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div = DIV_ROUND_UP(parent_rate, rate);
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if (!_is_valid_div(divider, div))
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return -EINVAL;
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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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if (divider->lock)
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spin_lock_irqsave(divider->lock, flags);
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if (divider->flags & CLK_DIVIDER_HIWORD_MASK) {
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val = div_mask(divider) << (divider->shift + 16);
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} else {
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val = clk_readl(divider->reg);
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val &= ~(div_mask(divider) << divider->shift);
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}
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val |= value << divider->shift;
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clk_writel(val, divider->reg);
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if (divider->lock)
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spin_unlock_irqrestore(divider->lock, flags);
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return 0;
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}
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const struct clk_ops clk_divider_ops = {
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.recalc_rate = clk_divider_recalc_rate,
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.round_rate = clk_divider_round_rate,
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.set_rate = clk_divider_set_rate,
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};
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EXPORT_SYMBOL_GPL(clk_divider_ops);
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static struct clk *_register_divider(struct device *dev, const char *name,
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const char *parent_name, unsigned long flags,
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void __iomem *reg, u8 shift, u8 width,
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u8 clk_divider_flags, const struct clk_div_table *table,
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spinlock_t *lock)
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{
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struct clk_divider *div;
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struct clk *clk;
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struct clk_init_data init;
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if (clk_divider_flags & CLK_DIVIDER_HIWORD_MASK) {
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if (width + shift > 16) {
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pr_warn("divider value exceeds LOWORD field\n");
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return ERR_PTR(-EINVAL);
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}
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}
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/* allocate the divider */
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div = kzalloc(sizeof(struct clk_divider), GFP_KERNEL);
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if (!div) {
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pr_err("%s: could not allocate divider clk\n", __func__);
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return ERR_PTR(-ENOMEM);
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}
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init.name = name;
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init.ops = &clk_divider_ops;
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init.flags = flags | CLK_IS_BASIC;
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init.parent_names = (parent_name ? &parent_name: NULL);
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init.num_parents = (parent_name ? 1 : 0);
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/* struct clk_divider assignments */
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div->reg = reg;
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div->shift = shift;
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div->width = width;
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div->flags = clk_divider_flags;
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div->lock = lock;
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div->hw.init = &init;
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div->table = table;
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/* register the clock */
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clk = clk_register(dev, &div->hw);
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if (IS_ERR(clk))
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kfree(div);
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return clk;
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}
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/**
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* clk_register_divider - register a divider clock with the clock framework
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* @dev: device registering this clock
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* @name: name of this clock
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* @parent_name: name of clock's parent
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* @flags: framework-specific flags
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* @reg: register address to adjust divider
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* @shift: number of bits to shift the bitfield
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* @width: width of the bitfield
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* @clk_divider_flags: divider-specific flags for this clock
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* @lock: shared register lock for this clock
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*/
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struct clk *clk_register_divider(struct device *dev, const char *name,
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const char *parent_name, unsigned long flags,
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void __iomem *reg, u8 shift, u8 width,
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u8 clk_divider_flags, spinlock_t *lock)
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{
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return _register_divider(dev, name, parent_name, flags, reg, shift,
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width, clk_divider_flags, NULL, lock);
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}
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EXPORT_SYMBOL_GPL(clk_register_divider);
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/**
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* clk_register_divider_table - register a table based divider clock with
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* the clock framework
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* @dev: device registering this clock
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* @name: name of this clock
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* @parent_name: name of clock's parent
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* @flags: framework-specific flags
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* @reg: register address to adjust divider
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* @shift: number of bits to shift the bitfield
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* @width: width of the bitfield
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* @clk_divider_flags: divider-specific flags for this clock
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* @table: array of divider/value pairs ending with a div set to 0
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* @lock: shared register lock for this clock
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*/
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struct clk *clk_register_divider_table(struct device *dev, const char *name,
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const char *parent_name, unsigned long flags,
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void __iomem *reg, u8 shift, u8 width,
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u8 clk_divider_flags, const struct clk_div_table *table,
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spinlock_t *lock)
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{
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return _register_divider(dev, name, parent_name, flags, reg, shift,
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width, clk_divider_flags, table, lock);
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}
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EXPORT_SYMBOL_GPL(clk_register_divider_table);
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