From: Emilio López <[email protected]>
This commit implements support for using the clk api; this lets us use
the "clocks" property with device tree, instead of having to use
clock-frequency.
Signed-off-by: Emilio López <[email protected]>
Signed-off-by: Maxime Ripard <[email protected]>
---
drivers/tty/serial/8250/8250_dw.c | 33 ++++++++++++++++++++++++---------
1 file changed, 24 insertions(+), 9 deletions(-)
diff --git a/drivers/tty/serial/8250/8250_dw.c b/drivers/tty/serial/8250/8250_dw.c
index db0e66f..9a834a1 100644
--- a/drivers/tty/serial/8250/8250_dw.c
+++ b/drivers/tty/serial/8250/8250_dw.c
@@ -26,6 +26,7 @@
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/acpi.h>
+#include <linux/clk.h>
#include "8250.h"
@@ -55,8 +56,9 @@
struct dw8250_data {
- int last_lcr;
- int line;
+ int last_lcr;
+ int line;
+ struct clk *clk;
};
static void dw8250_serial_out(struct uart_port *p, int offset, int value)
@@ -136,8 +138,13 @@ static int dw8250_probe_of(struct uart_port *p)
if (!of_property_read_u32(np, "reg-shift", &val))
p->regshift = val;
+ /* clock got configured through clk api, all done */
+ if (p->uartclk)
+ return 0;
+
+ /* try to find out clock frequency from DT as fallback */
if (of_property_read_u32(np, "clock-frequency", &val)) {
- dev_err(p->dev, "no clock-frequency property set\n");
+ dev_err(p->dev, "clk or clock-frequency not defined\n");
return -EINVAL;
}
p->uartclk = val;
@@ -294,9 +301,21 @@ static int dw8250_probe(struct platform_device *pdev)
if (!uart.port.membase)
return -ENOMEM;
+ data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
+ if (!data)
+ return -ENOMEM;
+
+ data->clk = devm_clk_get(&pdev->dev, NULL);
+ if (IS_ERR(data->clk))
+ data->clk = NULL;
+ else
+ clk_prepare_enable(data->clk);
+
uart.port.iotype = UPIO_MEM;
uart.port.serial_in = dw8250_serial_in;
uart.port.serial_out = dw8250_serial_out;
+ uart.port.private_data = data;
+ uart.port.uartclk = clk_get_rate(data->clk);
dw8250_setup_port(&uart);
@@ -312,12 +331,6 @@ static int dw8250_probe(struct platform_device *pdev)
return -ENODEV;
}
- data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
- if (!data)
- return -ENOMEM;
-
- uart.port.private_data = data;
-
data->line = serial8250_register_8250_port(&uart);
if (data->line < 0)
return data->line;
@@ -333,6 +346,8 @@ static int dw8250_remove(struct platform_device *pdev)
serial8250_unregister_port(data->line);
+ clk_disable_unprepare(data->clk);
+
return 0;
}
--
1.7.10.4
On Fri, Mar 15, 2013 at 09:06:23PM +0100, Maxime Ripard wrote:
> + /* clock got configured through clk api, all done */
> + if (p->uartclk)
if (IS_ERR(p->uartclk))
> + return 0;
> +
> + /* try to find out clock frequency from DT as fallback */
> if (of_property_read_u32(np, "clock-frequency", &val)) {
> - dev_err(p->dev, "no clock-frequency property set\n");
> + dev_err(p->dev, "clk or clock-frequency not defined\n");
> return -EINVAL;
> }
> p->uartclk = val;
> @@ -294,9 +301,21 @@ static int dw8250_probe(struct platform_device *pdev)
> if (!uart.port.membase)
> return -ENOMEM;
>
> + data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
> + if (!data)
> + return -ENOMEM;
> +
> + data->clk = devm_clk_get(&pdev->dev, NULL);
> + if (IS_ERR(data->clk))
> + data->clk = NULL;
> + else
> + clk_prepare_enable(data->clk);
if (!IS_ERR(data->clk))
clk_prepare_enable(data->clk);
> +
> uart.port.iotype = UPIO_MEM;
> uart.port.serial_in = dw8250_serial_in;
> uart.port.serial_out = dw8250_serial_out;
> + uart.port.private_data = data;
> + uart.port.uartclk = clk_get_rate(data->clk);
What if data->clk is invalid?
if (!IS_ERR(data->clk)
uart.port.uartclk = clk_get_rate(data->clk);
>
> dw8250_setup_port(&uart);
>
> @@ -312,12 +331,6 @@ static int dw8250_probe(struct platform_device *pdev)
> return -ENODEV;
> }
>
> - data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
> - if (!data)
> - return -ENOMEM;
> -
> - uart.port.private_data = data;
> -
> data->line = serial8250_register_8250_port(&uart);
> if (data->line < 0)
> return data->line;
> @@ -333,6 +346,8 @@ static int dw8250_remove(struct platform_device *pdev)
>
> serial8250_unregister_port(data->line);
>
if (!IS_ERR(data->clk)
> + clk_disable_unprepare(data->clk);
> +
> return 0;
> }
>
> --
> 1.7.10.4
>
>
> _______________________________________________
> linux-arm-kernel mailing list
> [email protected]
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
Hello Russell,
El 15/03/13 19:39, Russell King - ARM Linux escribi?:
> On Fri, Mar 15, 2013 at 09:06:23PM +0100, Maxime Ripard wrote:
>> + /* clock got configured through clk api, all done */
>> + if (p->uartclk)
>
> if (IS_ERR(p->uartclk))
>
Isn't IS_ERR for pointers? p->uartclk is an unsigned int
>> + return 0;
>> +
>> + /* try to find out clock frequency from DT as fallback */
>> if (of_property_read_u32(np, "clock-frequency", &val)) {
>> - dev_err(p->dev, "no clock-frequency property set\n");
>> + dev_err(p->dev, "clk or clock-frequency not defined\n");
>> return -EINVAL;
>> }
>> p->uartclk = val;
>> @@ -294,9 +301,21 @@ static int dw8250_probe(struct platform_device *pdev)
>> if (!uart.port.membase)
>> return -ENOMEM;
>>
>> + data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
>> + if (!data)
>> + return -ENOMEM;
>> +
>> + data->clk = devm_clk_get(&pdev->dev, NULL);
>> + if (IS_ERR(data->clk))
>> + data->clk = NULL;
>> + else
>> + clk_prepare_enable(data->clk);
>
> if (!IS_ERR(data->clk))
> clk_prepare_enable(data->clk);
>
See below
>> +
>> uart.port.iotype = UPIO_MEM;
>> uart.port.serial_in = dw8250_serial_in;
>> uart.port.serial_out = dw8250_serial_out;
>> + uart.port.private_data = data;
>> + uart.port.uartclk = clk_get_rate(data->clk);
>
> What if data->clk is invalid?
>
> if (!IS_ERR(data->clk)
> uart.port.uartclk = clk_get_rate(data->clk);
>
I'm not sure if it is coincidental or the way it is supposed to be, but
when using the common clock framework, if you pass a NULL to
clk_get_rate, the function explicitly checks for it and returns 0. I
relied on that behaviour when implementing this; see the if..else block
above. Is this not always the case on other clock drivers?
>>
>> dw8250_setup_port(&uart);
>>
>> @@ -312,12 +331,6 @@ static int dw8250_probe(struct platform_device *pdev)
>> return -ENODEV;
>> }
>>
>> - data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
>> - if (!data)
>> - return -ENOMEM;
>> -
>> - uart.port.private_data = data;
>> -
>> data->line = serial8250_register_8250_port(&uart);
>> if (data->line < 0)
>> return data->line;
>> @@ -333,6 +346,8 @@ static int dw8250_remove(struct platform_device *pdev)
>>
>> serial8250_unregister_port(data->line);
>>
>
> if (!IS_ERR(data->clk)
>
I just double checked and clk_enable/disable, clk_prepare/unprepare also
ignore NULLs passed to them on the CCF.
>> + clk_disable_unprepare(data->clk);
>> +
>> return 0;
>> }
>>
>> --
>> 1.7.10.4
Thanks for the review,
Emilio
On Fri, Mar 15, 2013 at 09:15:11PM -0300, Emilio L?pez wrote:
> Hello Russell,
>
> El 15/03/13 19:39, Russell King - ARM Linux escribi?:
> > On Fri, Mar 15, 2013 at 09:06:23PM +0100, Maxime Ripard wrote:
> >> + /* clock got configured through clk api, all done */
> >> + if (p->uartclk)
> >
> > if (IS_ERR(p->uartclk))
> >
>
> Isn't IS_ERR for pointers? p->uartclk is an unsigned int
Right, sorry, ignore that.
> >> + return 0;
> >> +
> >> + /* try to find out clock frequency from DT as fallback */
> >> if (of_property_read_u32(np, "clock-frequency", &val)) {
> >> - dev_err(p->dev, "no clock-frequency property set\n");
> >> + dev_err(p->dev, "clk or clock-frequency not defined\n");
> >> return -EINVAL;
> >> }
> >> p->uartclk = val;
> >> @@ -294,9 +301,21 @@ static int dw8250_probe(struct platform_device *pdev)
> >> if (!uart.port.membase)
> >> return -ENOMEM;
> >>
> >> + data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
> >> + if (!data)
> >> + return -ENOMEM;
> >> +
> >> + data->clk = devm_clk_get(&pdev->dev, NULL);
> >> + if (IS_ERR(data->clk))
> >> + data->clk = NULL;
> >> + else
> >> + clk_prepare_enable(data->clk);
> >
> > if (!IS_ERR(data->clk))
> > clk_prepare_enable(data->clk);
> >
>
> See below
>
> >> +
> >> uart.port.iotype = UPIO_MEM;
> >> uart.port.serial_in = dw8250_serial_in;
> >> uart.port.serial_out = dw8250_serial_out;
> >> + uart.port.private_data = data;
> >> + uart.port.uartclk = clk_get_rate(data->clk);
> >
> > What if data->clk is invalid?
> >
> > if (!IS_ERR(data->clk)
> > uart.port.uartclk = clk_get_rate(data->clk);
> >
>
> I'm not sure if it is coincidental or the way it is supposed to be, but
> when using the common clock framework, if you pass a NULL to
> clk_get_rate, the function explicitly checks for it and returns 0. I
> relied on that behaviour when implementing this; see the if..else block
> above. Is this not always the case on other clock drivers?
That's something that the common clock framework decided to do. It's
not a defined part of the API though, so drivers shouldn't rely on
this behaviour meaning anything special.
El 15/03/13 21:29, Russell King - ARM Linux escribi?:
> On Fri, Mar 15, 2013 at 09:15:11PM -0300, Emilio L?pez wrote:
>> Hello Russell,
>>
>> El 15/03/13 19:39, Russell King - ARM Linux escribi?:
>>> On Fri, Mar 15, 2013 at 09:06:23PM +0100, Maxime Ripard wrote:
>>>> + /* clock got configured through clk api, all done */
>>>> + if (p->uartclk)
>>>
>>> if (IS_ERR(p->uartclk))
>>>
>>
>> Isn't IS_ERR for pointers? p->uartclk is an unsigned int
>
> Right, sorry, ignore that.
>
>>>> + return 0;
>>>> +
>>>> + /* try to find out clock frequency from DT as fallback */
>>>> if (of_property_read_u32(np, "clock-frequency", &val)) {
>>>> - dev_err(p->dev, "no clock-frequency property set\n");
>>>> + dev_err(p->dev, "clk or clock-frequency not defined\n");
>>>> return -EINVAL;
>>>> }
>>>> p->uartclk = val;
>>>> @@ -294,9 +301,21 @@ static int dw8250_probe(struct platform_device *pdev)
>>>> if (!uart.port.membase)
>>>> return -ENOMEM;
>>>>
>>>> + data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
>>>> + if (!data)
>>>> + return -ENOMEM;
>>>> +
>>>> + data->clk = devm_clk_get(&pdev->dev, NULL);
>>>> + if (IS_ERR(data->clk))
>>>> + data->clk = NULL;
>>>> + else
>>>> + clk_prepare_enable(data->clk);
>>>
>>> if (!IS_ERR(data->clk))
>>> clk_prepare_enable(data->clk);
>>>
>>
>> See below
>>
>>>> +
>>>> uart.port.iotype = UPIO_MEM;
>>>> uart.port.serial_in = dw8250_serial_in;
>>>> uart.port.serial_out = dw8250_serial_out;
>>>> + uart.port.private_data = data;
>>>> + uart.port.uartclk = clk_get_rate(data->clk);
>>>
>>> What if data->clk is invalid?
>>>
>>> if (!IS_ERR(data->clk)
>>> uart.port.uartclk = clk_get_rate(data->clk);
>>>
>>
>> I'm not sure if it is coincidental or the way it is supposed to be, but
>> when using the common clock framework, if you pass a NULL to
>> clk_get_rate, the function explicitly checks for it and returns 0. I
>> relied on that behaviour when implementing this; see the if..else block
>> above. Is this not always the case on other clock drivers?
>
> That's something that the common clock framework decided to do. It's
> not a defined part of the API though, so drivers shouldn't rely on
> this behaviour meaning anything special.
Ok then, I'll rework the error checking on the clock calls and get a new
patch sent. Thanks for the clarification.
Emilio