[PATCH] mtd: nand: davinci: Add cpufreq support

[Ben Gardiner]

Hi Sudhakar,

On Thu, Jul 21, 2011 at 5:39 AM, Rajashekhara, Sudhakar
<sudhakar.raj at ti.com> wrote:
> This patch adds cpufreq support for NAND driver. During cpufreq
> transition, 'davinci_aemif_setup_timing()' function will be called
> to reconfigure that AEMIF timings for the new frequency.

I can see that this will work fine for dacinci_nand -- and it is a
welcomed feature also -- thank you for the effort to push this
upstream.

Seeing this support added directly to davinci_nand driver made me
think -- now this driver has another reference to platform-specific
functions in arch/arm/mach-davinci/aemif.c. Recently the c6x project
pushed a fix to remove references to a platform specific include. Not
that you are re-introducing this include but in a more general sense:
perhaps the features/functions of the AEMIF _bus_ should be removed
from the davinci_nand driver?

As for an in-tree driver example: how would support for cpufreq
transitions be added to the UI-board's NOR device which is currently
using "physmap-flash" driver?

> Tested on TI DA850/OMAP-L138 EVM.
>
> Signed-off-by: Rajashekhara, Sudhakar <sudhakar.raj at ti.com>
> ---
>  drivers/mtd/nand/davinci_nand.c |   54 +++++++++++++++++++++++++++++++++++++++
>  1 files changed, 54 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/mtd/nand/davinci_nand.c b/drivers/mtd/nand/davinci_nand.c
> index 1f34951..7e764af 100644
> --- a/drivers/mtd/nand/davinci_nand.c
> +++ b/drivers/mtd/nand/davinci_nand.c
> @@ -33,6 +33,7 @@
>  #include <linux/mtd/nand.h>
>  #include <linux/mtd/partitions.h>
>  #include <linux/slab.h>
> +#include <linux/cpufreq.h>
>
>  #include <mach/nand.h>
>  #include <mach/aemif.h>
> @@ -74,6 +75,9 @@ struct davinci_nand_info {
>        uint32_t                core_chipsel;
>
>        struct davinci_aemif_timing     *timing;
> +#ifdef CONFIG_CPU_FREQ
> +       struct notifier_block   freq_transition;
> +#endif
>  };
>
>  static DEFINE_SPINLOCK(davinci_nand_lock);
> @@ -519,6 +523,47 @@ static struct nand_ecclayout hwecc4_2048 __initconst = {
>        },
>  };
>
> +#ifdef CONFIG_CPU_FREQ
> +static int nand_davinci_cpufreq_transition(struct notifier_block *nb,
> +               unsigned long val, void *data)
> +{
> +       struct davinci_nand_info *info;
> +
> +       info = container_of(nb, struct davinci_nand_info, freq_transition);
> +
> +       if (val == CPUFREQ_POSTCHANGE)
> +               davinci_aemif_setup_timing(info->timing, info->base,
> +                               info->core_chipsel);
> +
> +       return 0;
> +}
> +
> +static inline int nand_davinci_cpufreq_register(struct davinci_nand_info *info)
> +{
> +       info->freq_transition.notifier_call = nand_davinci_cpufreq_transition;
> +
> +       return cpufreq_register_notifier(&info->freq_transition,
> +                       CPUFREQ_TRANSITION_NOTIFIER);
> +}
> +
> +static inline void nand_davinci_cpufreq_deregister(struct davinci_nand_info
> +               *info)
> +{
> +       cpufreq_unregister_notifier(&info->freq_transition,
> +                       CPUFREQ_TRANSITION_NOTIFIER);
> +}
> +#else
> +static inline int nand_davinci_cpufreq_register(struct davinci_nand_info *info)
> +{
> +       return 0;
> +}
> +
> +static inline void nand_davinci_cpufreq_deregister(struct davinci_nand_info
> +               *info)
> +{
> +}
> +#endif
> +
>  static int __init nand_davinci_probe(struct platform_device *pdev)
>  {
>        struct davinci_nand_pdata       *pdata = pdev->dev.platform_data;
> @@ -782,12 +827,19 @@ syndrome_done:
>        if (ret < 0)
>                goto err_scan;
>
> +       ret = nand_davinci_cpufreq_register(info);
> +       if (ret) {
> +               dev_err(&pdev->dev, "failed to register cpufreq\n");
> +               goto err_cpu_freq_fail;
> +       }
> +
>        val = davinci_nand_readl(info, NRCSR_OFFSET);
>        dev_info(&pdev->dev, "controller rev. %d.%d\n",
>               (val >> 8) & 0xff, val & 0xff);
>
>        return 0;
>
> +err_cpu_freq_fail:
>  err_scan:
>  err_timing:
>        clk_disable(info->clk);
> @@ -818,6 +870,8 @@ static int __exit nand_davinci_remove(struct platform_device *pdev)
>        struct davinci_nand_info *info = platform_get_drvdata(pdev);
>        int status;
>
> +       nand_davinci_cpufreq_deregister(info);
> +
>        status = mtd_device_unregister(&info->mtd);
>
>        spin_lock_irq(&davinci_nand_lock);
> --
> 1.7.1
>
> _______________________________________________
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> Davinci-linux-open-source at linux.davincidsp.com
> http://linux.davincidsp.com/mailman/listinfo/davinci-linux-open-source
>



-- 
Best Regards,
Ben Gardiner

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