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[PATCH v3 4/4] misc: atmel_tclib: get and use slow clock

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  [PATCH v3 4/4] misc: atmel_tclib: get and use slow clock Alexandre Belloni <alexandre.belloni@free-electrons.com> - 2015-08-11 12:00 +0200
    Re: [PATCH v3 4/4] misc: atmel_tclib: get and use slow clock Daniel Lezcano <daniel.lezcano@linaro.org> - 2015-08-11 15:50 +0200
      Re: [PATCH v3 4/4] misc: atmel_tclib: get and use slow clock Alexandre Belloni <alexandre.belloni@free-electrons.com> - 2015-08-11 17:30 +0200

#1204974 — [PATCH v3 4/4] misc: atmel_tclib: get and use slow clock

From: Boris Brezillon <boris.brezillon@free-electrons.com>

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@free-electrons.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: linux-pwm@vger.kernel.org

 drivers/clocksource/tcb_clksrc.c |  8 ++++++++
 drivers/misc/atmel_tclib.c       |  4 ++++
 drivers/pwm/pwm-atmel-tcb.c      | 23 ++++++++++++++++-------
 include/linux/atmel_tc.h         |  1 +
 4 files changed, 29 insertions(+), 7 deletions(-)

diff --git a/drivers/clocksource/tcb_clksrc.c b/drivers/clocksource/tcb_clksrc.c
index b9b7277173c2..969ba03633b0 100644
--- a/drivers/clocksource/tcb_clksrc.c
+++ b/drivers/clocksource/tcb_clksrc.c
@@ -188,6 +188,13 @@ static int __init setup_clkevents(struct atmel_tc *tc, int clk32k_divisor_idx)
 	ret = clk_prepare_enable(t2_clk);
 	if (ret)
 		return ret;
+
+	ret = clk_prepare_enable(tc->slow_clk);
+	if (ret) {
+		clk_disable_unprepare(t2_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..070a32a35295 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 +400,24 @@ 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_free_tc;
 
 	platform_set_drvdata(pdev, tcbpwm);
 
 	return 0;
+
+err_free_tc:
+	atmel_tc_free(tc);
+
+	return err;
 }
 
 static int atmel_tcb_pwm_remove(struct platform_device *pdev)
@@ -418,6 +425,8 @@ 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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#1205155

On 08/11/2015 11:38 AM, Alexandre Belloni wrote:
> From: Boris Brezillon <boris.brezillon@free-electrons.com>
>
> 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@free-electrons.com>
> Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> ---
> Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Thierry Reding <thierry.reding@gmail.com>
> Cc: linux-pwm@vger.kernel.org
>
>   drivers/clocksource/tcb_clksrc.c |  8 ++++++++
>   drivers/misc/atmel_tclib.c       |  4 ++++
>   drivers/pwm/pwm-atmel-tcb.c      | 23 ++++++++++++++++-------
>   include/linux/atmel_tc.h         |  1 +
>   4 files changed, 29 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/clocksource/tcb_clksrc.c b/drivers/clocksource/tcb_clksrc.c
> index b9b7277173c2..969ba03633b0 100644
> --- a/drivers/clocksource/tcb_clksrc.c
> +++ b/drivers/clocksource/tcb_clksrc.c
> @@ -188,6 +188,13 @@ static int __init setup_clkevents(struct atmel_tc *tc, int clk32k_divisor_idx)
>   	ret = clk_prepare_enable(t2_clk);
>   	if (ret)
>   		return ret;
> +
> +	ret = clk_prepare_enable(tc->slow_clk);
> +	if (ret) {
> +		clk_disable_unprepare(t2_clk);
> +		return ret;
> +	}
> +
>   	clk_disable(t2_clk);

Do you need t2_clk to be enabled in order to enable tc->slow_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

[ ... ]

> @@ -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 +400,24 @@ 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_free_tc;
>
>   	platform_set_drvdata(pdev, tcbpwm);
>
>   	return 0;
> +
> +err_free_tc:
> +	atmel_tc_free(tc);
> +
> +	return err;

What about clk_unprepare_disable(tc->slow_clk) ?

>   }
>

[ ... ]


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#1205214

On 11/08/2015 at 15:40:45 +0200, Daniel Lezcano wrote :
> On 08/11/2015 11:38 AM, Alexandre Belloni wrote:
> >From: Boris Brezillon <boris.brezillon@free-electrons.com>
> >
> >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@free-electrons.com>
> >Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
> >Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> >---
> >Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
> >Cc: Thomas Gleixner <tglx@linutronix.de>
> >Cc: Thierry Reding <thierry.reding@gmail.com>
> >Cc: linux-pwm@vger.kernel.org
> >
> >  drivers/clocksource/tcb_clksrc.c |  8 ++++++++
> >  drivers/misc/atmel_tclib.c       |  4 ++++
> >  drivers/pwm/pwm-atmel-tcb.c      | 23 ++++++++++++++++-------
> >  include/linux/atmel_tc.h         |  1 +
> >  4 files changed, 29 insertions(+), 7 deletions(-)
> >
> >diff --git a/drivers/clocksource/tcb_clksrc.c b/drivers/clocksource/tcb_clksrc.c
> >index b9b7277173c2..969ba03633b0 100644
> >--- a/drivers/clocksource/tcb_clksrc.c
> >+++ b/drivers/clocksource/tcb_clksrc.c
> >@@ -188,6 +188,13 @@ static int __init setup_clkevents(struct atmel_tc *tc, int clk32k_divisor_idx)
> >  	ret = clk_prepare_enable(t2_clk);
> >  	if (ret)
> >  		return ret;
> >+
> >+	ret = clk_prepare_enable(tc->slow_clk);
> >+	if (ret) {
> >+		clk_disable_unprepare(t2_clk);
> >+		return ret;
> >+	}
> >+
> >  	clk_disable(t2_clk);
> 
> Do you need t2_clk to be enabled in order to enable tc->slow_clk ?

No, I'll move clk_prepare_enable for tc->slow_clk before t2_clk.

> >+
> >+err_free_tc:
> >+	atmel_tc_free(tc);
> >+
> >+	return err;
> 
> What about clk_unprepare_disable(tc->slow_clk) ?
> 

Indeed, I trusted Boris a bit too much ;)

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http://free-electrons.com
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