Subject: Re: [RFC 4/4] [powerpc] Add flexcan device support for p1010rdb.

From: Wolfgang Grandegger <[email-masked]>
Date: Tue, 09 Aug 2011 09:11:33 +0200

On 08/09/2011 08:33 AM, Robin Holt wrote:
> Argh.  I sent an earlier (non-working) version of this patch.  Here is
> the correct one.

Please always resend the complete series of patches with an incremented
version number. Furthermore, this is not an RFC any more. A prefix
similar to [PATCH nfsl_get_sys_freq() et-next-2.6 v2] would be perfect.

> I added a clock source for the p1010rdb so the flexcan driver
> could find its clock frequency.
> 
> Signed-off-by: Robin Holt <[email-masked]>
> To: Marc Kleine-Budde <[email-masked]>,
> To: Wolfgang Grandegger <[email-masked]>,
> To: U Bhaskar-B22300 <[email-masked]>
> Cc: [email-masked],
> Cc: [email-masked],
> Cc: PPC list <[email-masked]>
> ---
>  arch/powerpc/platforms/85xx/Kconfig    |    6 +++
>  arch/powerpc/platforms/85xx/Makefile   |    1 +
>  arch/powerpc/platforms/85xx/clock.c    |   59 ++++++++++++++++++++++++++++++++
>  arch/powerpc/platforms/85xx/p1010rdb.c |   10 +++++
>  4 files changed, 76 insertions(+), 0 deletions(-)
>  create mode 100644 arch/powerpc/platforms/85xx/clock.c
> 
> diff --git a/arch/powerpc/platforms/85xx/Kconfig b/arch/powerpc/platforms/85xx/Kconfig
> index 498534c..ed4cf92 100644
> --- a/arch/powerpc/platforms/85xx/Kconfig
> +++ b/arch/powerpc/platforms/85xx/Kconfig
> @@ -26,6 +26,10 @@ config MPC8560_ADS
>  	help
>  	  This option enables support for the MPC 8560 ADS board
>  
> +config 85xx_HAVE_CAN_FLEXCAN
> +	bool
> +	select HAVE_CAN_FLEXCAN if NET && CAN
> +

Why do you need that? More below...

>  config MPC85xx_CDS
>  	bool "Freescale MPC85xx CDS"
>  	select DEFAULT_UIMAGE
> @@ -70,6 +74,8 @@ config MPC85xx_RDB
>  config P1010_RDB
>  	bool "Freescale P1010RDB"
>  	select DEFAULT_UIMAGE
> +	select 85xx_HAVE_CAN_FLEXCAN
> +	select PPC_CLOCK if CAN_FLEXCAN

	select HAVE_CAN_FLEXCAN
	select PPC_CLOCK

Should just be fine, or have I missed something.

>  	help
>  	  This option enables support for the MPC85xx RDB (P1010 RDB) board
>  
> diff --git a/arch/powerpc/platforms/85xx/Makefile b/arch/powerpc/platforms/85xx/Makefile
> index a971b32..64ad7a4 100644
> --- a/arch/powerpc/platforms/85xx/Makefile
> +++ b/arch/powerpc/platforms/85xx/Makefile
> @@ -11,6 +11,7 @@ obj-$(CONFIG_MPC85xx_DS)  += mpc85xx_ds.o
>  obj-$(CONFIG_MPC85xx_MDS) += mpc85xx_mds.o
>  obj-$(CONFIG_MPC85xx_RDB) += mpc85xx_rdb.o
>  obj-$(CONFIG_P1010_RDB)   += p1010rdb.o
> +obj-$(CONFIG_PPC_CLOCK)   += clock.o

I would put that to the beginning or before the board settings.

>  obj-$(CONFIG_P1022_DS)    += p1022_ds.o
>  obj-$(CONFIG_P1023_RDS)   += p1023_rds.o
>  obj-$(CONFIG_P2040_RDB)   += p2040_rdb.o corenet_ds.o
> diff --git a/arch/powerpc/platforms/85xx/clock.c b/arch/powerpc/platforms/85xx/clock.c
> new file mode 100644
> index 0000000..a25cbf3
> --- /dev/null
> +++ b/arch/powerpc/platforms/85xx/clock.c
> @@ -0,0 +1,59 @@
> +
> +#include <linux/device.h>
> +#include <linux/err.h>
> +
> +#include <asm/clk_interface.h>
> +
> +#include <sysdev/fsl_soc.h>
> +
> +/*
> + * p1010rdb needs to provide a clock source for the flexcan driver.
> + */
> +struct clk {
> +	unsigned long rate;
> +} p1010_rdb_system_clock;
> +
> +static struct clk *p1010_rdb_clk_get(struct device *dev, const char *id)
> +{
> +	const char *dev_init_name;
> +
> +	if (!dev)
> +		return ERR_PTR(-ENOENT);
> +
> +	/*
> +	 * The can devices are named ffe1c000.can0 and ffe1d000.can1 on
> +	 * the p1010rdb.  Check for the "can" portion of that name before
> +	 * returning a clock source.
> +	 */
> +	dev_init_name = dev_name(dev);
> +	if (strlen(dev_init_name) != 13)
> +		return ERR_PTR(-ENOENT);
> +	dev_init_name += 9;
> +	if (strncmp(dev_init_name, "can", 3))
> +		return ERR_PTR(-ENOENT);

What's that good for? Also it's wrong to rely on the special name of the
node. I think it can be removed.

> +	return &p1010_rdb_system_clock;

Just returning fsl_get_sys_freq() here would already be fine. I'm also
missing the factor of two here:

        return fsl_get_sys_freq() / 2; ????

> +}
> +
> +static void p1010_rdb_clk_put(struct clk *clk)
> +{
> +	return;
> +}
> +
> +static unsigned long p1010_rdb_clk_get_rate(struct clk *clk)
> +{
> +	return clk->rate;
> +}
> +
> +static struct clk_interface p1010_rdb_clk_functions = {
> +	.clk_get		= p1010_rdb_clk_get,
> +	.clk_get_rate		= p1010_rdb_clk_get_rate,
> +	.clk_put		= p1010_rdb_clk_put,
> +};
> +
> +void __init p1010_rdb_clk_init(void)
> +{
> +	p1010_rdb_system_clock.rate = fsl_get_sys_freq();

> +	clk_functions = p1010_rdb_clk_functions;
> +}

The name is too specific. The idea is that the interface could be used
for other 85xx processors as well, not only the p1010. The prefix
"mpc85xx_" instead of "p1010_rdb" seems more appropriate to me.

> diff --git a/arch/powerpc/platforms/85xx/p1010rdb.c b/arch/powerpc/platforms/85xx/p1010rdb.c
> index d7387fa..d0afbf9 100644
> --- a/arch/powerpc/platforms/85xx/p1010rdb.c
> +++ b/arch/powerpc/platforms/85xx/p1010rdb.c
> @@ -81,6 +81,15 @@ static void __init p1010_rdb_setup_arch(void)
>  	printk(KERN_INFO "P1010 RDB board from Freescale Semiconductor\n");
>  }
>  
> +extern void p1010_rdb_clk_init(void);
> +
> +static void __init p1010_rdb_init(void)
> +{
> +#ifdef CONFIG_PPC_CLOCK
> +	p1010_rdb_clk_init();
> +#endif
> +}

The #ifdef's are not needed if CONFIG_PPC_CLOCK is selected in the Kconfig.

>  static struct of_device_id __initdata p1010rdb_ids[] = {
>  	{ .type = "soc", },
>  	{ .compatible = "soc", },
> @@ -111,6 +120,7 @@ define_machine(p1010_rdb) {
>  	.name			= "P1010 RDB",
>  	.probe			= p1010_rdb_probe,
>  	.setup_arch		= p1010_rdb_setup_arch,
> +	.init			= p1010_rdb_init,
>  	.init_IRQ		= p1010_rdb_pic_init,
>  #ifdef CONFIG_PCI
>  	.pcibios_fixup_bus	= fsl_pcibios_fixup_bus,

We also need cleanup patches for the Freescale stuff.

Thanks,

Wolfgang.