[RFC v6 03/23] clocksource: em_sti: split clock prepare and enable steps

Nicolai Stange
2016-09-09T20:01:11Z

Currently, the em_sti driver prepares and enables the needed clock in
em_sti_enable(), potentially called through its clockevent device's
->set_state_oneshot().

However, the clk_prepare() step may sleep whereas tick_program_event() and
thus, ->set_state_oneshot(), can be called in atomic context.

Split the clk_prepare_enable() in em_sti_enable() into two steps:
- prepare the clock at device probing via clk_prepare()
- and enable it in em_sti_enable() via clk_enable().
Slightly reorder resource initialization in em_sti_probe() in order to
facilitate error handling.

Signed-off-by: Nicolai Stange <nicstange@gmail.com>
---

Notes:
Compile-only tested on ARCH=arm.

drivers/clocksource/em_sti.c | 25 ++++++++++++++++++-------
1 file changed, 18 insertions(+), 7 deletions(-)

diff --git a/drivers/clocksource/em_sti.c b/drivers/clocksource/em_sti.c
index 19bb179..46750c0 100644
--- a/drivers/clocksource/em_sti.c
+++ b/drivers/clocksource/em_sti.c
@@ -78,7 +78,7 @@ static int em_sti_enable(struct em_sti_priv *p)
int ret;

/* enable clock */
- ret = clk_prepare_enable(p->clk);
+ ret = clk_enable(p->clk);
if (ret) {
dev_err(&p->pdev->dev, "cannot enable clock\n");
return ret;
@@ -107,7 +107,7 @@ static void em_sti_disable(struct em_sti_priv *p)
em_sti_write(p, STI_INTENCLR, 3);

/* stop clock */
- clk_disable_unprepare(p->clk);
+ clk_disable(p->clk);
}

static cycle_t em_sti_count(struct em_sti_priv *p)
@@ -303,6 +303,7 @@ static int em_sti_probe(struct platform_device *pdev)
struct em_sti_priv *p;
struct resource *res;
int irq;
+ int ret;

p = devm_kzalloc(&pdev->dev, sizeof(*p), GFP_KERNEL);
if (p == NULL)
@@ -323,6 +324,13 @@ static int em_sti_probe(struct platform_device *pdev)
if (IS_ERR(p->base))
return PTR_ERR(p->base);

+ if (devm_request_irq(&pdev->dev, irq, em_sti_interrupt,
+ IRQF_TIMER | IRQF_IRQPOLL | IRQF_NOBALANCING,
+ dev_name(&pdev->dev), p)) {
+ dev_err(&pdev->dev, "failed to request low IRQ\n");
+ return -ENOENT;
+ }
+
/* get hold of clock */
p->clk = devm_clk_get(&pdev->dev, "sclk");
if (IS_ERR(p->clk)) {
@@ -330,17 +338,20 @@ static int em_sti_probe(struct platform_device *pdev)
return PTR_ERR(p->clk);
}

- if (devm_request_irq(&pdev->dev, irq, em_sti_interrupt,
- IRQF_TIMER | IRQF_IRQPOLL | IRQF_NOBALANCING,
- dev_name(&pdev->dev), p)) {
- dev_err(&pdev->dev, "failed to request low IRQ\n");
- return -ENOENT;
+ ret = clk_prepare(p->clk);
+ if (ret < 0) {
+ dev_err(&pdev->dev, "cannot prepare clock\n");
+ goto err_clk_put;
}

raw_spin_lock_init(&p->lock);
em_sti_register_clockevent(p);
em_sti_register_clocksource(p);
return 0;
+
+err_clk_put:
+ clk_put(p->clk);
+ return ret;
}

static int em_sti_remove(struct platform_device *pdev)
--
2.9.3