[1/2] serial: mps2-uart: move to dynamic port allocation
diff mbox series

Message ID 1548425597-38175-2-git-send-email-vladimir.murzin@arm.com
State New, archived
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Series
  • serial: mps2-uart: minor improvements
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Commit Message

Vladimir Murzin Jan. 25, 2019, 2:13 p.m. UTC
Some designs, like MPS3, expose number of virtual serial ports which
already close or exceeds MPS2_MAX_PORTS. Increasing MPS2_MAX_PORTS
would have negative impact (in terms of memory consumption) on tiny
MPS2 platform which, in fact, has only one physically populated UART.

Start with converting existent static port array to idr. As a bonus it
make driver not to fail in case when no alias was specified in device
tree.

Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
---
 drivers/tty/serial/mps2-uart.c | 47 ++++++++++++++++++++++++++++--------------
 1 file changed, 31 insertions(+), 16 deletions(-)

Comments

Greg KH Jan. 30, 2019, 8:27 a.m. UTC | #1
On Fri, Jan 25, 2019 at 02:13:16PM +0000, Vladimir Murzin wrote:
> Some designs, like MPS3, expose number of virtual serial ports which
> already close or exceeds MPS2_MAX_PORTS. Increasing MPS2_MAX_PORTS
> would have negative impact (in terms of memory consumption) on tiny
> MPS2 platform which, in fact, has only one physically populated UART.
> 
> Start with converting existent static port array to idr. As a bonus it
> make driver not to fail in case when no alias was specified in device
> tree.
> 
> Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
> ---
>  drivers/tty/serial/mps2-uart.c | 47 ++++++++++++++++++++++++++++--------------
>  1 file changed, 31 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/tty/serial/mps2-uart.c b/drivers/tty/serial/mps2-uart.c
> index 9f8f637..6da0633 100644
> --- a/drivers/tty/serial/mps2-uart.c
> +++ b/drivers/tty/serial/mps2-uart.c
> @@ -22,6 +22,7 @@
>  #include <linux/serial_core.h>
>  #include <linux/tty_flip.h>
>  #include <linux/types.h>
> +#include <linux/idr.h>
>  
>  #define SERIAL_NAME	"ttyMPS"
>  #define DRIVER_NAME	"mps2-uart"
> @@ -397,7 +398,7 @@ static const struct uart_ops mps2_uart_pops = {
>  	.verify_port = mps2_uart_verify_port,
>  };
>  
> -static struct mps2_uart_port mps2_uart_ports[MPS2_MAX_PORTS];
> +static DEFINE_IDR(ports_idr);

You forgot to call idr_destroy() when your code unloads :(

Yeah, it's not an obvious design pattern, I think someone will fix it up
someday...

thanks,

greg k-h
Vladimir Murzin Jan. 30, 2019, 8:58 a.m. UTC | #2
On 1/30/19 8:27 AM, Greg KH wrote:
> On Fri, Jan 25, 2019 at 02:13:16PM +0000, Vladimir Murzin wrote:
>> Some designs, like MPS3, expose number of virtual serial ports which
>> already close or exceeds MPS2_MAX_PORTS. Increasing MPS2_MAX_PORTS
>> would have negative impact (in terms of memory consumption) on tiny
>> MPS2 platform which, in fact, has only one physically populated UART.
>>
>> Start with converting existent static port array to idr. As a bonus it
>> make driver not to fail in case when no alias was specified in device
>> tree.
>>
>> Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
>> ---
>>  drivers/tty/serial/mps2-uart.c | 47 ++++++++++++++++++++++++++++--------------
>>  1 file changed, 31 insertions(+), 16 deletions(-)
>>
>> diff --git a/drivers/tty/serial/mps2-uart.c b/drivers/tty/serial/mps2-uart.c
>> index 9f8f637..6da0633 100644
>> --- a/drivers/tty/serial/mps2-uart.c
>> +++ b/drivers/tty/serial/mps2-uart.c
>> @@ -22,6 +22,7 @@
>>  #include <linux/serial_core.h>
>>  #include <linux/tty_flip.h>
>>  #include <linux/types.h>
>> +#include <linux/idr.h>
>>  
>>  #define SERIAL_NAME	"ttyMPS"
>>  #define DRIVER_NAME	"mps2-uart"
>> @@ -397,7 +398,7 @@ static const struct uart_ops mps2_uart_pops = {
>>  	.verify_port = mps2_uart_verify_port,
>>  };
>>  
>> -static struct mps2_uart_port mps2_uart_ports[MPS2_MAX_PORTS];
>> +static DEFINE_IDR(ports_idr);
> 
> You forgot to call idr_destroy() when your code unloads :(

Hmm, but code doesn't unload since ce87122911f8 ("serial: mps2-uart: make driver explicitly non-modular")
or I'm missing something?

Cheers
Vladimir

> 
> Yeah, it's not an obvious design pattern, I think someone will fix it up
> someday...
> 
> thanks,
> 
> greg k-h
>
Greg KH Jan. 30, 2019, 9:24 a.m. UTC | #3
On Wed, Jan 30, 2019 at 08:58:53AM +0000, Vladimir Murzin wrote:
> On 1/30/19 8:27 AM, Greg KH wrote:
> > On Fri, Jan 25, 2019 at 02:13:16PM +0000, Vladimir Murzin wrote:
> >> Some designs, like MPS3, expose number of virtual serial ports which
> >> already close or exceeds MPS2_MAX_PORTS. Increasing MPS2_MAX_PORTS
> >> would have negative impact (in terms of memory consumption) on tiny
> >> MPS2 platform which, in fact, has only one physically populated UART.
> >>
> >> Start with converting existent static port array to idr. As a bonus it
> >> make driver not to fail in case when no alias was specified in device
> >> tree.
> >>
> >> Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
> >> ---
> >>  drivers/tty/serial/mps2-uart.c | 47 ++++++++++++++++++++++++++++--------------
> >>  1 file changed, 31 insertions(+), 16 deletions(-)
> >>
> >> diff --git a/drivers/tty/serial/mps2-uart.c b/drivers/tty/serial/mps2-uart.c
> >> index 9f8f637..6da0633 100644
> >> --- a/drivers/tty/serial/mps2-uart.c
> >> +++ b/drivers/tty/serial/mps2-uart.c
> >> @@ -22,6 +22,7 @@
> >>  #include <linux/serial_core.h>
> >>  #include <linux/tty_flip.h>
> >>  #include <linux/types.h>
> >> +#include <linux/idr.h>
> >>  
> >>  #define SERIAL_NAME	"ttyMPS"
> >>  #define DRIVER_NAME	"mps2-uart"
> >> @@ -397,7 +398,7 @@ static const struct uart_ops mps2_uart_pops = {
> >>  	.verify_port = mps2_uart_verify_port,
> >>  };
> >>  
> >> -static struct mps2_uart_port mps2_uart_ports[MPS2_MAX_PORTS];
> >> +static DEFINE_IDR(ports_idr);
> > 
> > You forgot to call idr_destroy() when your code unloads :(
> 
> Hmm, but code doesn't unload since ce87122911f8 ("serial: mps2-uart: make driver explicitly non-modular")
> or I'm missing something?

Ugh, ok, nevermind, I missed that, sorry.

greg k-h
Vladimir Murzin Jan. 30, 2019, 9:33 a.m. UTC | #4
On 1/30/19 9:24 AM, Greg KH wrote:
> On Wed, Jan 30, 2019 at 08:58:53AM +0000, Vladimir Murzin wrote:
>> On 1/30/19 8:27 AM, Greg KH wrote:
>>> On Fri, Jan 25, 2019 at 02:13:16PM +0000, Vladimir Murzin wrote:
>>>> Some designs, like MPS3, expose number of virtual serial ports which
>>>> already close or exceeds MPS2_MAX_PORTS. Increasing MPS2_MAX_PORTS
>>>> would have negative impact (in terms of memory consumption) on tiny
>>>> MPS2 platform which, in fact, has only one physically populated UART.
>>>>
>>>> Start with converting existent static port array to idr. As a bonus it
>>>> make driver not to fail in case when no alias was specified in device
>>>> tree.
>>>>
>>>> Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
>>>> ---
>>>>  drivers/tty/serial/mps2-uart.c | 47 ++++++++++++++++++++++++++++--------------
>>>>  1 file changed, 31 insertions(+), 16 deletions(-)
>>>>
>>>> diff --git a/drivers/tty/serial/mps2-uart.c b/drivers/tty/serial/mps2-uart.c
>>>> index 9f8f637..6da0633 100644
>>>> --- a/drivers/tty/serial/mps2-uart.c
>>>> +++ b/drivers/tty/serial/mps2-uart.c
>>>> @@ -22,6 +22,7 @@
>>>>  #include <linux/serial_core.h>
>>>>  #include <linux/tty_flip.h>
>>>>  #include <linux/types.h>
>>>> +#include <linux/idr.h>
>>>>  
>>>>  #define SERIAL_NAME	"ttyMPS"
>>>>  #define DRIVER_NAME	"mps2-uart"
>>>> @@ -397,7 +398,7 @@ static const struct uart_ops mps2_uart_pops = {
>>>>  	.verify_port = mps2_uart_verify_port,
>>>>  };
>>>>  
>>>> -static struct mps2_uart_port mps2_uart_ports[MPS2_MAX_PORTS];
>>>> +static DEFINE_IDR(ports_idr);
>>>
>>> You forgot to call idr_destroy() when your code unloads :(
>>
>> Hmm, but code doesn't unload since ce87122911f8 ("serial: mps2-uart: make driver explicitly non-modular")
>> or I'm missing something?
> 
> Ugh, ok, nevermind, I missed that, sorry.

No problem, I'll add a note about that in commit message ;)

Thanks
Vladimir

> 
> greg k-h
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>

Patch
diff mbox series

diff --git a/drivers/tty/serial/mps2-uart.c b/drivers/tty/serial/mps2-uart.c
index 9f8f637..6da0633 100644
--- a/drivers/tty/serial/mps2-uart.c
+++ b/drivers/tty/serial/mps2-uart.c
@@ -22,6 +22,7 @@ 
 #include <linux/serial_core.h>
 #include <linux/tty_flip.h>
 #include <linux/types.h>
+#include <linux/idr.h>
 
 #define SERIAL_NAME	"ttyMPS"
 #define DRIVER_NAME	"mps2-uart"
@@ -397,7 +398,7 @@  static const struct uart_ops mps2_uart_pops = {
 	.verify_port = mps2_uart_verify_port,
 };
 
-static struct mps2_uart_port mps2_uart_ports[MPS2_MAX_PORTS];
+static DEFINE_IDR(ports_idr);
 
 #ifdef CONFIG_SERIAL_MPS2_UART_CONSOLE
 static void mps2_uart_console_putchar(struct uart_port *port, int ch)
@@ -410,7 +411,8 @@  static void mps2_uart_console_putchar(struct uart_port *port, int ch)
 
 static void mps2_uart_console_write(struct console *co, const char *s, unsigned int cnt)
 {
-	struct uart_port *port = &mps2_uart_ports[co->index].port;
+	struct mps2_uart_port *mps_port = idr_find(&ports_idr, co->index);
+	struct uart_port *port = &mps_port->port;
 
 	uart_console_write(port, s, cnt, mps2_uart_console_putchar);
 }
@@ -426,7 +428,10 @@  static int mps2_uart_console_setup(struct console *co, char *options)
 	if (co->index < 0 || co->index >= MPS2_MAX_PORTS)
 		return -ENODEV;
 
-	mps_port = &mps2_uart_ports[co->index];
+	mps_port = idr_find(&ports_idr, co->index);
+
+	if (!mps_port)
+		return -ENODEV;
 
 	if (options)
 		uart_parse_options(options, &baud, &parity, &bits, &flow);
@@ -487,27 +492,32 @@  static struct uart_driver mps2_uart_driver = {
 	.cons = MPS2_SERIAL_CONSOLE,
 };
 
-static struct mps2_uart_port *mps2_of_get_port(struct platform_device *pdev)
+static int mps2_of_get_port(struct platform_device *pdev,
+			    struct mps2_uart_port *mps_port)
 {
 	struct device_node *np = pdev->dev.of_node;
 	int id;
 
 	if (!np)
-		return NULL;
+		return -ENODEV;
 
 	id = of_alias_get_id(np, "serial");
+
+	if (id < 0)
+		id = idr_alloc_cyclic(&ports_idr, (void *)mps_port, 0, MPS2_MAX_PORTS, GFP_KERNEL);
+	else
+		id = idr_alloc(&ports_idr, (void *)mps_port, id, MPS2_MAX_PORTS, GFP_KERNEL);
+
 	if (id < 0)
-		id = 0;
+		return id;
 
-	if (WARN_ON(id >= MPS2_MAX_PORTS))
-		return NULL;
+	mps_port->port.line = id;
 
-	mps2_uart_ports[id].port.line = id;
-	return &mps2_uart_ports[id];
+	return 0;
 }
 
-static int mps2_init_port(struct mps2_uart_port *mps_port,
-			  struct platform_device *pdev)
+static int mps2_init_port(struct platform_device *pdev,
+			  struct mps2_uart_port *mps_port)
 {
 	struct resource *res;
 	int ret;
@@ -550,11 +560,16 @@  static int mps2_serial_probe(struct platform_device *pdev)
 	struct mps2_uart_port *mps_port;
 	int ret;
 
-	mps_port = mps2_of_get_port(pdev);
-	if (!mps_port)
-		return -ENODEV;
+	mps_port = devm_kzalloc(&pdev->dev, sizeof(struct mps2_uart_port), GFP_KERNEL);
+
+        if (!mps_port)
+                return -ENOMEM;
+
+	ret = mps2_of_get_port(pdev, mps_port);
+	if (ret)
+		return ret;
 
-	ret = mps2_init_port(mps_port, pdev);
+	ret = mps2_init_port(pdev, mps_port);
 	if (ret)
 		return ret;