* [PATCH] USB: ohci-at91: add usb_clk for transition to common clk framework
@ 2013-08-01 6:16 Boris BREZILLON
2013-08-01 14:39 ` Alan Stern
0 siblings, 1 reply; 6+ messages in thread
From: Boris BREZILLON @ 2013-08-01 6:16 UTC (permalink / raw)
To: linux-arm-kernel
The AT91 PMC (Power Management Controller) provides an USB clock used by
USB Full Speed host (ohci) and USB Full Speed device (udc).
The usb drivers (ohci and udc) must configure this clock to 48Mhz.
This configuration was formely done in mach-at91/clock.c, but this
implementation will be removed when moving to common clk framework.
This patch adds support for usb clock retrieval and configuration, and is
backward compatible with the current at91 clk implementation (if usb clk
is not found, it does not configure/enable it).
Signed-off-by: Boris BREZILLON <b.brezillon@overkiz.com>
---
drivers/usb/host/ohci-at91.c | 17 +++++++++++++++--
1 file changed, 15 insertions(+), 2 deletions(-)
diff --git a/drivers/usb/host/ohci-at91.c b/drivers/usb/host/ohci-at91.c
index 9677f68..913d293 100644
--- a/drivers/usb/host/ohci-at91.c
+++ b/drivers/usb/host/ohci-at91.c
@@ -31,8 +31,8 @@
#define at91_for_each_port(index) \
for ((index) = 0; (index) < AT91_MAX_USBH_PORTS; (index)++)
-/* interface and function clocks; sometimes also an AHB clock */
-static struct clk *iclk, *fclk, *hclk;
+/* interface, function and usb clocks; sometimes also an AHB clock */
+static struct clk *iclk, *fclk, *uclk, *hclk;
static int clocked;
extern int usb_disabled(void);
@@ -41,6 +41,10 @@ extern int usb_disabled(void);
static void at91_start_clock(void)
{
+ if (!IS_ERR(uclk)) {
+ clk_set_rate(uclk, 48000000);
+ clk_prepare_enable(uclk);
+ }
clk_prepare_enable(hclk);
clk_prepare_enable(iclk);
clk_prepare_enable(fclk);
@@ -52,6 +56,8 @@ static void at91_stop_clock(void)
clk_disable_unprepare(fclk);
clk_disable_unprepare(iclk);
clk_disable_unprepare(hclk);
+ if (!IS_ERR(uclk))
+ clk_disable_unprepare(uclk);
clocked = 0;
}
@@ -163,6 +169,8 @@ static int usb_hcd_at91_probe(const struct hc_driver *driver,
goto err5;
}
+ uclk = clk_get(&pdev->dev, "usb_clk");
+
at91_start_hc(pdev);
ohci_hcd_init(hcd_to_ohci(hcd));
@@ -173,6 +181,9 @@ static int usb_hcd_at91_probe(const struct hc_driver *driver,
/* Error handling */
at91_stop_hc(pdev);
+ if (!IS_ERR(uclk))
+ clk_put(uclk);
+
clk_put(hclk);
err5:
clk_put(fclk);
@@ -212,6 +223,8 @@ static void usb_hcd_at91_remove(struct usb_hcd *hcd,
release_mem_region(hcd->rsrc_start, hcd->rsrc_len);
usb_put_hcd(hcd);
+ if (!IS_ERR(uclk))
+ clk_put(uclk);
clk_put(hclk);
clk_put(fclk);
clk_put(iclk);
--
1.7.9.5
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH] USB: ohci-at91: add usb_clk for transition to common clk framework
2013-08-01 6:16 [PATCH] USB: ohci-at91: add usb_clk for transition to common clk framework Boris BREZILLON
@ 2013-08-01 14:39 ` Alan Stern
2013-08-01 15:14 ` boris brezillon
0 siblings, 1 reply; 6+ messages in thread
From: Alan Stern @ 2013-08-01 14:39 UTC (permalink / raw)
To: linux-arm-kernel
On Thu, 1 Aug 2013, Boris BREZILLON wrote:
> The AT91 PMC (Power Management Controller) provides an USB clock used by
> USB Full Speed host (ohci) and USB Full Speed device (udc).
> The usb drivers (ohci and udc) must configure this clock to 48Mhz.
> This configuration was formely done in mach-at91/clock.c, but this
> implementation will be removed when moving to common clk framework.
>
> This patch adds support for usb clock retrieval and configuration, and is
> backward compatible with the current at91 clk implementation (if usb clk
> is not found, it does not configure/enable it).
>
> Signed-off-by: Boris BREZILLON <b.brezillon@overkiz.com>
> @@ -163,6 +169,8 @@ static int usb_hcd_at91_probe(const struct hc_driver *driver,
> goto err5;
> }
>
> + uclk = clk_get(&pdev->dev, "usb_clk");
What happens if uclk isn't found but it is needed?
Alan Stern
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH] USB: ohci-at91: add usb_clk for transition to common clk framework
2013-08-01 14:39 ` Alan Stern
@ 2013-08-01 15:14 ` boris brezillon
2013-08-01 15:56 ` Alan Stern
0 siblings, 1 reply; 6+ messages in thread
From: boris brezillon @ 2013-08-01 15:14 UTC (permalink / raw)
To: linux-arm-kernel
On 01/08/2013 16:39, Alan Stern wrote:
> On Thu, 1 Aug 2013, Boris BREZILLON wrote:
>
>> The AT91 PMC (Power Management Controller) provides an USB clock used by
>> USB Full Speed host (ohci) and USB Full Speed device (udc).
>> The usb drivers (ohci and udc) must configure this clock to 48Mhz.
>> This configuration was formely done in mach-at91/clock.c, but this
>> implementation will be removed when moving to common clk framework.
>>
>> This patch adds support for usb clock retrieval and configuration, and is
>> backward compatible with the current at91 clk implementation (if usb clk
>> is not found, it does not configure/enable it).
>>
>> Signed-off-by: Boris BREZILLON <b.brezillon@overkiz.com>
>> @@ -163,6 +169,8 @@ static int usb_hcd_at91_probe(const struct hc_driver *driver,
>> goto err5;
>> }
>>
>> + uclk = clk_get(&pdev->dev, "usb_clk");
> What happens if uclk isn't found but it is needed?
It will not fail but I guess the usb host won't work as the clock won't
be correctly
configured.
I agree with you: this is not a good solution.
Another option is to keep the previous version of this patch and put
uclk handling
in "#ifdef CONFIG_COMMON_CLK #endif" sections.
Would this be acceptable ?
>
> Alan Stern
>
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH] USB: ohci-at91: add usb_clk for transition to common clk framework
2013-08-01 15:14 ` boris brezillon
@ 2013-08-01 15:56 ` Alan Stern
2013-08-01 17:30 ` Sergei Shtylyov
0 siblings, 1 reply; 6+ messages in thread
From: Alan Stern @ 2013-08-01 15:56 UTC (permalink / raw)
To: linux-arm-kernel
On Thu, 1 Aug 2013, boris brezillon wrote:
> > What happens if uclk isn't found but it is needed?
> It will not fail but I guess the usb host won't work as the clock won't
> be correctly
> configured.
>
> I agree with you: this is not a good solution.
>
> Another option is to keep the previous version of this patch and put
> uclk handling
> in "#ifdef CONFIG_COMMON_CLK #endif" sections.
>
> Would this be acceptable ?
Yes. However, a more elegant approach is to protect the relevant
statements with: if (defined(CONFIG_COMMON_CLK)). This preprocessor
evaluates this to a 0 or 1, so the compiler will not generate output
for the protected source code if the symbol isn't defined.
Alan Stern
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH] USB: ohci-at91: add usb_clk for transition to common clk framework
2013-08-01 15:56 ` Alan Stern
@ 2013-08-01 17:30 ` Sergei Shtylyov
2013-08-01 17:38 ` Alan Stern
0 siblings, 1 reply; 6+ messages in thread
From: Sergei Shtylyov @ 2013-08-01 17:30 UTC (permalink / raw)
To: linux-arm-kernel
Hello.
On 08/01/2013 07:56 PM, Alan Stern wrote:
>>> What happens if uclk isn't found but it is needed?
>> It will not fail but I guess the usb host won't work as the clock won't
>> be correctly
>> configured.
>> I agree with you: this is not a good solution.
>> Another option is to keep the previous version of this patch and put
>> uclk handling
>> in "#ifdef CONFIG_COMMON_CLK #endif" sections.
>> Would this be acceptable ?
> Yes. However, a more elegant approach is to protect the relevant
> statements with: if (defined(CONFIG_COMMON_CLK)). This preprocessor
You probably meant IS_ENABLED() or IS_BUIILTIN()? Or is there something I
don't know about gcc preprocessor?
> evaluates this to a 0 or 1, so the compiler will not generate output
> for the protected source code if the symbol isn't defined.
> Alan Stern
WBR, Sergei
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH] USB: ohci-at91: add usb_clk for transition to common clk framework
2013-08-01 17:30 ` Sergei Shtylyov
@ 2013-08-01 17:38 ` Alan Stern
0 siblings, 0 replies; 6+ messages in thread
From: Alan Stern @ 2013-08-01 17:38 UTC (permalink / raw)
To: linux-arm-kernel
On Thu, 1 Aug 2013, Sergei Shtylyov wrote:
> > Yes. However, a more elegant approach is to protect the relevant
> > statements with: if (defined(CONFIG_COMMON_CLK)). This preprocessor
>
> You probably meant IS_ENABLED() or IS_BUIILTIN()? Or is there something I
> don't know about gcc preprocessor?
Yes, sorry, I meant IS_ENABLED(). Boris got it right.
Alan Stern
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2013-08-01 17:38 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
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2013-08-01 6:16 [PATCH] USB: ohci-at91: add usb_clk for transition to common clk framework Boris BREZILLON
2013-08-01 14:39 ` Alan Stern
2013-08-01 15:14 ` boris brezillon
2013-08-01 15:56 ` Alan Stern
2013-08-01 17:30 ` Sergei Shtylyov
2013-08-01 17:38 ` Alan Stern
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