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99a8170652
The AT91 clock drivers make use of IRQs to avoid polling when waiting for some clocks to be enabled. Unfortunately, this leads to a crash when those IRQs are threaded (which happens when using preempt-rt) because they are registered before thread creation is possible. Use polling on those clocks instead to avoid the problem. Acked-by: Stephen Boyd <sboyd@codeaurora.org> Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
159 lines
3.4 KiB
C
159 lines
3.4 KiB
C
/*
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* Copyright (C) 2013 Boris BREZILLON <b.brezillon@overkiz.com>
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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 as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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*/
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#include <linux/clk-provider.h>
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#include <linux/clkdev.h>
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#include <linux/clk/at91_pmc.h>
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#include <linux/of.h>
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#include <linux/mfd/syscon.h>
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#include <linux/regmap.h>
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#include "pmc.h"
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#define SYSTEM_MAX_ID 31
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#define SYSTEM_MAX_NAME_SZ 32
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#define to_clk_system(hw) container_of(hw, struct clk_system, hw)
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struct clk_system {
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struct clk_hw hw;
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struct regmap *regmap;
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u8 id;
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};
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static inline int is_pck(int id)
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{
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return (id >= 8) && (id <= 15);
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}
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static inline bool clk_system_ready(struct regmap *regmap, int id)
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{
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unsigned int status;
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regmap_read(regmap, AT91_PMC_SR, &status);
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return status & (1 << id) ? 1 : 0;
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}
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static int clk_system_prepare(struct clk_hw *hw)
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{
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struct clk_system *sys = to_clk_system(hw);
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regmap_write(sys->regmap, AT91_PMC_SCER, 1 << sys->id);
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if (!is_pck(sys->id))
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return 0;
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while (!clk_system_ready(sys->regmap, sys->id))
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cpu_relax();
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return 0;
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}
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static void clk_system_unprepare(struct clk_hw *hw)
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{
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struct clk_system *sys = to_clk_system(hw);
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regmap_write(sys->regmap, AT91_PMC_SCDR, 1 << sys->id);
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}
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static int clk_system_is_prepared(struct clk_hw *hw)
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{
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struct clk_system *sys = to_clk_system(hw);
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unsigned int status;
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regmap_read(sys->regmap, AT91_PMC_SCSR, &status);
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if (!(status & (1 << sys->id)))
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return 0;
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if (!is_pck(sys->id))
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return 1;
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regmap_read(sys->regmap, AT91_PMC_SR, &status);
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return status & (1 << sys->id) ? 1 : 0;
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}
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static const struct clk_ops system_ops = {
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.prepare = clk_system_prepare,
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.unprepare = clk_system_unprepare,
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.is_prepared = clk_system_is_prepared,
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};
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static struct clk * __init
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at91_clk_register_system(struct regmap *regmap, const char *name,
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const char *parent_name, u8 id)
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{
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struct clk_system *sys;
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struct clk *clk = NULL;
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struct clk_init_data init;
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if (!parent_name || id > SYSTEM_MAX_ID)
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return ERR_PTR(-EINVAL);
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sys = kzalloc(sizeof(*sys), GFP_KERNEL);
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if (!sys)
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return ERR_PTR(-ENOMEM);
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init.name = name;
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init.ops = &system_ops;
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init.parent_names = &parent_name;
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init.num_parents = 1;
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init.flags = CLK_SET_RATE_PARENT;
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sys->id = id;
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sys->hw.init = &init;
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sys->regmap = regmap;
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clk = clk_register(NULL, &sys->hw);
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if (IS_ERR(clk))
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kfree(sys);
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return clk;
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}
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static void __init of_at91rm9200_clk_sys_setup(struct device_node *np)
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{
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int num;
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u32 id;
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struct clk *clk;
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const char *name;
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struct device_node *sysclknp;
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const char *parent_name;
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struct regmap *regmap;
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num = of_get_child_count(np);
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if (num > (SYSTEM_MAX_ID + 1))
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return;
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regmap = syscon_node_to_regmap(of_get_parent(np));
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if (IS_ERR(regmap))
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return;
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for_each_child_of_node(np, sysclknp) {
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if (of_property_read_u32(sysclknp, "reg", &id))
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continue;
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if (of_property_read_string(np, "clock-output-names", &name))
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name = sysclknp->name;
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parent_name = of_clk_get_parent_name(sysclknp, 0);
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clk = at91_clk_register_system(regmap, name, parent_name, id);
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if (IS_ERR(clk))
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continue;
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of_clk_add_provider(sysclknp, of_clk_src_simple_get, clk);
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}
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}
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CLK_OF_DECLARE(at91rm9200_clk_sys, "atmel,at91rm9200-clk-system",
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of_at91rm9200_clk_sys_setup);
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