[PATCH v4 4/4] misc: atmel_tclib: get and use slow clock

From: Alexandre Belloni
Date: Sun Aug 16 2015 - 05:25:45 EST


From: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxxxxxxx>

Commit dca1a4b5ff6e ("clk: at91: keep slow clk enabled to prevent system
hang") added a workaround for the slow clock as it is not properly handled
by its users.

Get and use the slow clock as it is necessary for the timer counters.

Signed-off-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxxxxxxxxx>
Acked-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
Cc: Daniel Lezcano <daniel.lezcano@xxxxxxxxxx>
Cc: Thierry Reding <thierry.reding@xxxxxxxxx>
Cc: linux-pwm@xxxxxxxxxxxxxxx
drivers/clocksource/tcb_clksrc.c | 10 +++++++++-
drivers/misc/atmel_tclib.c | 4 ++++
drivers/pwm/pwm-atmel-tcb.c | 26 +++++++++++++++++++-------
include/linux/atmel_tc.h | 1 +
4 files changed, 33 insertions(+), 8 deletions(-)

diff --git a/drivers/clocksource/tcb_clksrc.c b/drivers/clocksource/tcb_clksrc.c
index b9b7277173c2..ba1e5d55d3bf 100644
--- a/drivers/clocksource/tcb_clksrc.c
+++ b/drivers/clocksource/tcb_clksrc.c
@@ -184,10 +184,17 @@ static int __init setup_clkevents(struct atmel_tc *tc, int clk32k_divisor_idx)
struct clk *t2_clk = tc->clk[2];
int irq = tc->irq[2];

+ ret = clk_prepare_enable(tc->slow_clk);
+ if (ret)
+ return ret;
+
/* try to enable t2 clk to avoid future errors in mode change */
ret = clk_prepare_enable(t2_clk);
- if (ret)
+ if (ret) {
+ clk_disable_unprepare(tc->slow_clk);
return ret;
+ }
+
clk_disable(t2_clk);

clkevt.regs = tc->regs;
@@ -200,6 +207,7 @@ static int __init setup_clkevents(struct atmel_tc *tc, int clk32k_divisor_idx)
ret = request_irq(irq, ch2_irq, IRQF_TIMER, "tc_clkevt", &clkevt);
if (ret) {
clk_unprepare(t2_clk);
+ clk_disable_unprepare(tc->slow_clk);
return ret;
}

diff --git a/drivers/misc/atmel_tclib.c b/drivers/misc/atmel_tclib.c
index 0ca05c3ec8d6..ac24a4bd63f7 100644
--- a/drivers/misc/atmel_tclib.c
+++ b/drivers/misc/atmel_tclib.c
@@ -125,6 +125,10 @@ static int __init tc_probe(struct platform_device *pdev)
if (IS_ERR(clk))
return PTR_ERR(clk);

+ tc->slow_clk = devm_clk_get(&pdev->dev, "slow_clk");
+ if (IS_ERR(tc->slow_clk))
+ return PTR_ERR(tc->slow_clk);
+
r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
tc->regs = devm_ioremap_resource(&pdev->dev, r);
if (IS_ERR(tc->regs))
diff --git a/drivers/pwm/pwm-atmel-tcb.c b/drivers/pwm/pwm-atmel-tcb.c
index d14e0677c92d..f64ee392f620 100644
--- a/drivers/pwm/pwm-atmel-tcb.c
+++ b/drivers/pwm/pwm-atmel-tcb.c
@@ -305,7 +305,7 @@ static int atmel_tcb_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
*/
if (i == 5) {
i = slowclk;
- rate = 32768;
+ rate = clk_get_rate(tc->slow_clk);
min = div_u64(NSEC_PER_SEC, rate);
max = min << tc->tcb_config->counter_width;

@@ -387,9 +387,9 @@ static int atmel_tcb_pwm_probe(struct platform_device *pdev)

tcbpwm = devm_kzalloc(&pdev->dev, sizeof(*tcbpwm), GFP_KERNEL);
if (tcbpwm == NULL) {
- atmel_tc_free(tc);
+ err = -ENOMEM;
dev_err(&pdev->dev, "failed to allocate memory\n");
- return -ENOMEM;
+ goto err_free_tc;
}

tcbpwm->chip.dev = &pdev->dev;
@@ -400,17 +400,27 @@ static int atmel_tcb_pwm_probe(struct platform_device *pdev)
tcbpwm->chip.npwm = NPWM;
tcbpwm->tc = tc;

+ err = clk_prepare_enable(tc->slow_clk);
+ if (err)
+ goto err_free_tc;
+
spin_lock_init(&tcbpwm->lock);

err = pwmchip_add(&tcbpwm->chip);
- if (err < 0) {
- atmel_tc_free(tc);
- return err;
- }
+ if (err < 0)
+ goto err_disable_clk;

platform_set_drvdata(pdev, tcbpwm);

return 0;
+
+err_disable_clk:
+ clk_disable_unprepare(tcbpwm->tc->slow_clk);
+
+err_free_tc:
+ atmel_tc_free(tc);
+
+ return err;
}

static int atmel_tcb_pwm_remove(struct platform_device *pdev)
@@ -418,6 +428,8 @@ static int atmel_tcb_pwm_remove(struct platform_device *pdev)
struct atmel_tcb_pwm_chip *tcbpwm = platform_get_drvdata(pdev);
int err;

+ clk_disable_unprepare(tcbpwm->tc->slow_clk);
+
err = pwmchip_remove(&tcbpwm->chip);
if (err < 0)
return err;
diff --git a/include/linux/atmel_tc.h b/include/linux/atmel_tc.h
index b87c1c7c242a..468fdfa643f0 100644
--- a/include/linux/atmel_tc.h
+++ b/include/linux/atmel_tc.h
@@ -67,6 +67,7 @@ struct atmel_tc {
const struct atmel_tcb_config *tcb_config;
int irq[3];
struct clk *clk[3];
+ struct clk *slow_clk;
struct list_head node;
bool allocated;
};
--
2.1.4

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