On 08/11/2011 05:56 AM, Robin Holt wrote:
> On Wed, Aug 10, 2011 at 08:16:33PM +0200, Wolfgang Grandegger wrote:
>> On 08/10/2011 07:01 PM, Kumar Gala wrote:
>>>
>>> On Aug 10, 2011, at 11:27 AM, Robin Holt wrote:
>>>
>>>> I added a simple clock source for the p1010rdb so the flexcan driver
>>>> could determine a clock frequency. The p1010 flexcan device only has
>>>> an oscillator of system bus frequency divided by 2.
>>>>
>>>> Signed-off-by: Robin Holt <h...@sgi.com>
>>>> Acked-by: Marc Kleine-Budde <m...@pengutronix.de>,
>>>> Acked-by: Wolfgang Grandegger <w...@grandegger.com>,
>>>> Cc: U Bhaskar-B22300 <b22...@freescale.com>
>>>> Cc: socketcan-core@lists.berlios.de,
>>>> Cc: net...@vger.kernel.org,
>>>> Cc: PPC list <linuxppc-...@lists.ozlabs.org>
>>>> Cc: Kumar Gala <ga...@kernel.crashing.org>
>>>> ---
>>>> arch/powerpc/platforms/85xx/Kconfig | 2 +
>>>> arch/powerpc/platforms/85xx/Makefile | 2 +
>>>> arch/powerpc/platforms/85xx/clock.c | 52
>>>> ++++++++++++++++++++++++++++++++
>>>> arch/powerpc/platforms/85xx/p1010rdb.c | 8 +++++
>>>> 4 files changed, 64 insertions(+), 0 deletions(-)
>>>> create mode 100644 arch/powerpc/platforms/85xx/clock.c
>>>
>>> I dont understand how mpc85xx_clk_functions() ends up being associated with
>>> the frequency the flexcan is running at.
>>
>> The function mpc85xx_clk_get_rate() returns "fsl_get_sys_freq() / 2" for
>> Flexcan devices.
>>
>>> This either seems to global or I'm missing something.
>>
>> This patch extends the existing Flexcan platform driver for ARM for the
>> PowerPC using the device tree. Due to the nice integration of the device
>> tree (of-platform) into the platform driver and devices, the difference
>> are quite small (see patches 1..3). Apart from the endianess issue, only
>> the clock needs to be handled in a common way. As ARM already uses the
>> clk interface, we found it straight-forward to implement it for the
>> P1010, or more general for the 85xx, as well, instead of using an
>> additional helper function.
>>
>>> I still think the clk / freq info should be in the device tree and handled
>>> in the driver and NOT arch/powerpc platform code.
>>
>> If I understand you correctly, you want the boot-loader to provide the
>> relevant information by fixing up the device tree, which then can be
>> handled arch-independently by the driver, right?
>
> Marc and Wolfgang,
>
> This is a very early swag at this which I worked up while driving home from
> dinner
> this evening. It works with my current config, but that includes at least one
> bogus patch. I will have to do more testing tomorrow. For now, it is
> something
> to ponder.
Yes, that's what Kumar is proposing. Fine for me with the P1010. It just
needs some proper U-Boot implementation.
> Thanks,
> Robin
> ------------------------------------------------------------------------
>
> flexcan: Prefer device tree clock frequency if available.
>
> If our CAN device's device tree node has a clock-frequency property,
> then use that value for the can devices clock frequency. If not, fall
> back to asking the platform/mach code for the clock frequency associated
> with the flexcan device.
>
> Too-early-to-be-signed-off-by: Robin Holt <h...@sgi.com>
>
> diff --git a/drivers/net/can/flexcan.c b/drivers/net/can/flexcan.c
> index 662f832..d6a87c9 100644
> --- a/drivers/net/can/flexcan.c
> +++ b/drivers/net/can/flexcan.c
> @@ -33,6 +33,7 @@
> #include <linux/kernel.h>
> #include <linux/list.h>
> #include <linux/module.h>
> +#include <linux/of.h>
> #include <linux/platform_device.h>
>
> #define DRV_NAME "flexcan"
> @@ -929,12 +930,25 @@ static int __devinit flexcan_probe(struct
> platform_device *pdev)
> void __iomem *base;
> resource_size_t mem_size;
> int err, irq;
> + u32 clock_freq = 0;
>
> - clk = clk_get(&pdev->dev, NULL);
> - if (IS_ERR(clk)) {
> - dev_err(&pdev->dev, "no clock defined\n");
> - err = PTR_ERR(clk);
> - goto failed_clock;
> + if (pdev->dev.of_node) {
> + u32 *clock_freq_p;
Should be:
const u32 *clock_freq_p;
> +
> + clk = NULL;
> + clock_freq_p = (u32 *)of_get_property(pdev->dev.of_node,
> "clock-frequency", NULL);
No cast please.
> + if (clock_freq_p)
> + clock_freq = *clock_freq_p;
> + }
Wolfgang.
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