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clk: at91: remove IRQ handling and use polling

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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>
This commit is contained in:
Alexandre Belloni
2015-09-16 23:47:39 +02:00
parent 1bdf02326b
commit 99a8170652
7 changed files with 37 additions and 446 deletions
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47
drivers/clk/at91/clk-pll.c
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@@ -12,14 +12,6 @@
#include <linux/clkdev.h>
#include <linux/clk/at91_pmc.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/wait.h>
#include <linux/sched.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/mfd/syscon.h>
#include <linux/regmap.h>
@@ -61,8 +53,6 @@ struct clk_pll_layout {
struct clk_pll {
struct clk_hw hw;
struct regmap *regmap;
unsigned int irq;
wait_queue_head_t wait;
u8 id;
u8 div;
u8 range;
@@ -71,16 +61,6 @@ struct clk_pll {
const struct clk_pll_characteristics *characteristics;
};
static irqreturn_t clk_pll_irq_handler(int irq, void *dev_id)
{
struct clk_pll *pll = (struct clk_pll *)dev_id;
wake_up(&pll->wait);
disable_irq_nosync(pll->irq);
return IRQ_HANDLED;
}
static inline bool clk_pll_ready(struct regmap *regmap, int id)
{
unsigned int status;
@@ -127,11 +107,8 @@ static int clk_pll_prepare(struct clk_hw *hw)
(out << PLL_OUT_SHIFT) |
((pll->mul & layout->mul_mask) << layout->mul_shift));
while (!clk_pll_ready(regmap, pll->id)) {
enable_irq(pll->irq);
wait_event(pll->wait,
clk_pll_ready(regmap, pll->id));
}
while (!clk_pll_ready(regmap, pll->id))
cpu_relax();
return 0;
}
@@ -320,7 +297,7 @@ static const struct clk_ops pll_ops = {
};
static struct clk * __init
at91_clk_register_pll(struct regmap *regmap, unsigned int irq, const char *name,
at91_clk_register_pll(struct regmap *regmap, const char *name,
const char *parent_name, u8 id,
const struct clk_pll_layout *layout,
const struct clk_pll_characteristics *characteristics)
@@ -328,7 +305,6 @@ at91_clk_register_pll(struct regmap *regmap, unsigned int irq, const char *name,
struct clk_pll *pll;
struct clk *clk = NULL;
struct clk_init_data init;
int ret;
int offset = PLL_REG(id);
unsigned int pllr;
@@ -350,22 +326,12 @@ at91_clk_register_pll(struct regmap *regmap, unsigned int irq, const char *name,
pll->layout = layout;
pll->characteristics = characteristics;
pll->regmap = regmap;
pll->irq = irq;
regmap_read(regmap, offset, &pllr);
pll->div = PLL_DIV(pllr);
pll->mul = PLL_MUL(pllr, layout);
init_waitqueue_head(&pll->wait);
irq_set_status_flags(pll->irq, IRQ_NOAUTOEN);
ret = request_irq(pll->irq, clk_pll_irq_handler, IRQF_TRIGGER_HIGH,
id ? "clk-pllb" : "clk-plla", pll);
if (ret) {
kfree(pll);
return ERR_PTR(ret);
}
clk = clk_register(NULL, &pll->hw);
if (IS_ERR(clk)) {
free_irq(pll->irq, pll);
kfree(pll);
}
@@ -499,7 +465,6 @@ of_at91_clk_pll_setup(struct device_node *np,
const struct clk_pll_layout *layout)
{
u32 id;
unsigned int irq;
struct clk *clk;
struct regmap *regmap;
const char *parent_name;
@@ -521,11 +486,7 @@ of_at91_clk_pll_setup(struct device_node *np,
if (!characteristics)
return;
irq = irq_of_parse_and_map(np, 0);
if (!irq)
return;
clk = at91_clk_register_pll(regmap, irq, name, parent_name, id, layout,
clk = at91_clk_register_pll(regmap, name, parent_name, id, layout,
characteristics);
if (IS_ERR(clk))
goto out_free_characteristics;