[PATCH v2] serial: 8250_of: Add reset support

[PATCH v2] serial: 8250_of: Add reset support

[Joel Stanley]

This adds the hooks for an optional reset controller in the 8250 device
tree node.

Signed-off-by: Joel Stanley <joel-U3u1mxZcP9KHXe+LvDLADg@public.gmane.org>

---
v2:
 Address Philipp's comments. Thanks for the review!
 - use _shared variant
 - remove unnecessary error handling

 Documentation/devicetree/bindings/serial/8250.txt |  1 +
 drivers/tty/serial/8250/8250_of.c                 | 10 ++++++++++
 2 files changed, 11 insertions(+)

diff --git a/Documentation/devicetree/bindings/serial/8250.txt b/Documentation/devicetree/bindings/serial/8250.txt
index 10276a46ecef..63e32393f82b 100644
--- a/Documentation/devicetree/bindings/serial/8250.txt
+++ b/Documentation/devicetree/bindings/serial/8250.txt
@@ -45,6 +45,7 @@ Optional properties:
   property.
 - tx-threshold: Specify the TX FIFO low water indication for parts with
   programmable TX FIFO thresholds.
+- resets : phandle + reset specifier pairs
 
 Note:
 * fsl,ns16550:
diff --git a/drivers/tty/serial/8250/8250_of.c b/drivers/tty/serial/8250/8250_of.c
index 1cbadafc6889..e95cc9698c32 100644
--- a/drivers/tty/serial/8250/8250_of.c
+++ b/drivers/tty/serial/8250/8250_of.c
@@ -19,11 +19,13 @@
 #include <linux/of_irq.h>
 #include <linux/of_platform.h>
 #include <linux/clk.h>
+#include <linux/reset.h>
 
 #include "8250.h"
 
 struct of_serial_info {
 	struct clk *clk;
+	struct reset_control *rst;
 	int type;
 	int line;
 };
@@ -132,6 +134,13 @@ static int of_platform_serial_setup(struct platform_device *ofdev,
 		}
 	}
 
+	info->rst = devm_reset_control_get_optional_shared(&ofdev->dev, NULL);
+	if (IS_ERR(info->rst))
+		goto out;
+	ret = reset_control_deassert(info->rst);
+	if (ret)
+		goto out;
+
 	port->type = type;
 	port->uartclk = clk;
 	port->flags = UPF_SHARE_IRQ | UPF_BOOT_AUTOCONF | UPF_IOREMAP
@@ -231,6 +240,7 @@ static int of_platform_serial_remove(struct platform_device *ofdev)
 
 	if (info->clk)
 		clk_disable_unprepare(info->clk);
+	reset_control_assert(info->rst);
 	kfree(info);
 	return 0;
 }
-- 
2.11.0

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Re: [PATCH v2] serial: 8250_of: Add reset support

[Philipp Zabel]

Hi Joel,

On Fri, 2017-05-26 at 11:55 +1000, Joel Stanley wrote:
> This adds the hooks for an optional reset controller in the 8250 device
> tree node.
> 
> Signed-off-by: Joel Stanley <joel-U3u1mxZcP9KHXe+LvDLADg@public.gmane.org>
> 
> ---
> v2:
>  Address Philipp's comments. Thanks for the review!
>  - use _shared variant
>  - remove unnecessary error handling
> 
>  Documentation/devicetree/bindings/serial/8250.txt |  1 +
>  drivers/tty/serial/8250/8250_of.c                 | 10 ++++++++++
>  2 files changed, 11 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/serial/8250.txt b/Documentation/devicetree/bindings/serial/8250.txt
> index 10276a46ecef..63e32393f82b 100644
> --- a/Documentation/devicetree/bindings/serial/8250.txt
> +++ b/Documentation/devicetree/bindings/serial/8250.txt
> @@ -45,6 +45,7 @@ Optional properties:
>    property.
>  - tx-threshold: Specify the TX FIFO low water indication for parts with
>    programmable TX FIFO thresholds.
> +- resets : phandle + reset specifier pairs
>  
>  Note:
>  * fsl,ns16550:
> diff --git a/drivers/tty/serial/8250/8250_of.c b/drivers/tty/serial/8250/8250_of.c
> index 1cbadafc6889..e95cc9698c32 100644
> --- a/drivers/tty/serial/8250/8250_of.c
> +++ b/drivers/tty/serial/8250/8250_of.c
> @@ -19,11 +19,13 @@
>  #include <linux/of_irq.h>
>  #include <linux/of_platform.h>
>  #include <linux/clk.h>
> +#include <linux/reset.h>
>  
>  #include "8250.h"
>  
>  struct of_serial_info {
>  	struct clk *clk;
> +	struct reset_control *rst;
>  	int type;
>  	int line;
>  };
> @@ -132,6 +134,13 @@ static int of_platform_serial_setup(struct platform_device *ofdev,
>  		}
>  	}
>  
> +	info->rst = devm_reset_control_get_optional_shared(&ofdev->dev, NULL);
> +	if (IS_ERR(info->rst))
> +		goto out;
> +	ret = reset_control_deassert(info->rst);
> +	if (ret)
> +		goto out;
> +
>  	port->type = type;
>  	port->uartclk = clk;
>  	port->flags = UPF_SHARE_IRQ | UPF_BOOT_AUTOCONF | UPF_IOREMAP
> @@ -231,6 +240,7 @@ static int of_platform_serial_remove(struct platform_device *ofdev)
>  
>  	if (info->clk)
>  		clk_disable_unprepare(info->clk);
> +	reset_control_assert(info->rst);

The clock is enabled before the reset is deasserted in
of_platform_serial_setup, I'd disable it after asserting the reset in
of_platform_serial_remove. Other than that,

Reviewed-by: Philipp Zabel <p.zabel-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>

regards
Philipp

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Re: [PATCH v2] serial: 8250_of: Add reset support

[Joel Stanley]

On Mon, May 29, 2017 at 7:13 PM, Philipp Zabel <p.zabel-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org> wrote:
> Hi Joel,
>
> On Fri, 2017-05-26 at 11:55 +1000, Joel Stanley wrote:
>> This adds the hooks for an optional reset controller in the 8250 device
>> tree node.
>>
>> Signed-off-by: Joel Stanley <joel-U3u1mxZcP9KHXe+LvDLADg@public.gmane.org>
>>
>> ---
>> v2:
>>  Address Philipp's comments. Thanks for the review!
>>  - use _shared variant
>>  - remove unnecessary error handling
>>
>>  Documentation/devicetree/bindings/serial/8250.txt |  1 +
>>  drivers/tty/serial/8250/8250_of.c                 | 10 ++++++++++
>>  2 files changed, 11 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/serial/8250.txt b/Documentation/devicetree/bindings/serial/8250.txt
>> index 10276a46ecef..63e32393f82b 100644
>> --- a/Documentation/devicetree/bindings/serial/8250.txt
>> +++ b/Documentation/devicetree/bindings/serial/8250.txt
>> @@ -45,6 +45,7 @@ Optional properties:
>>    property.
>>  - tx-threshold: Specify the TX FIFO low water indication for parts with
>>    programmable TX FIFO thresholds.
>> +- resets : phandle + reset specifier pairs
>>
>>  Note:
>>  * fsl,ns16550:
>> diff --git a/drivers/tty/serial/8250/8250_of.c b/drivers/tty/serial/8250/8250_of.c
>> index 1cbadafc6889..e95cc9698c32 100644
>> --- a/drivers/tty/serial/8250/8250_of.c
>> +++ b/drivers/tty/serial/8250/8250_of.c
>> @@ -19,11 +19,13 @@
>>  #include <linux/of_irq.h>
>>  #include <linux/of_platform.h>
>>  #include <linux/clk.h>
>> +#include <linux/reset.h>
>>
>>  #include "8250.h"
>>
>>  struct of_serial_info {
>>       struct clk *clk;
>> +     struct reset_control *rst;
>>       int type;
>>       int line;
>>  };
>> @@ -132,6 +134,13 @@ static int of_platform_serial_setup(struct platform_device *ofdev,
>>               }
>>       }
>>
>> +     info->rst = devm_reset_control_get_optional_shared(&ofdev->dev, NULL);
>> +     if (IS_ERR(info->rst))
>> +             goto out;
>> +     ret = reset_control_deassert(info->rst);
>> +     if (ret)
>> +             goto out;
>> +
>>       port->type = type;
>>       port->uartclk = clk;
>>       port->flags = UPF_SHARE_IRQ | UPF_BOOT_AUTOCONF | UPF_IOREMAP
>> @@ -231,6 +240,7 @@ static int of_platform_serial_remove(struct platform_device *ofdev)
>>
>>       if (info->clk)
>>               clk_disable_unprepare(info->clk);
>> +     reset_control_assert(info->rst);
>
> The clock is enabled before the reset is deasserted in
> of_platform_serial_setup, I'd disable it after asserting the reset in
> of_platform_serial_remove. Other than that,
>
> Reviewed-by: Philipp Zabel <p.zabel-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>

Doh, I'll send a v3 with your reviewed-by attached.

Thanks!

Joel
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