[PATCH] cpufreq: OMAP: instantiate omap-cpufreq as a platform_driver

[Rafael J. Wysocki]

On Tuesday, April 09, 2013 04:22:01 PM Kevin Hilman wrote:
> From: Nishanth Menon <nm at ti.com>
> 
> As multi-platform build is being adopted by more and more ARM platforms,
> initcall function should be used very carefully.  For example, when
> CONFIG_ARM_OMAP2PLUS_CPUFREQ is built in the kernel, omap_cpufreq_init()
> will be called on all the platforms to initialize omap-cpufreq driver.
> 
> Further, on OMAP, we now use Soc generic cpufreq-cpu0 driver using device
> tree entries.  To allow cpufreq-cpu0 and omap-cpufreq drivers to co-exist
> for OMAP in a single image, we need to ensure the following:
> 1. With device tree boot, we use cpufreq-cpu0
> 2. With non device tree boot, we use omap-cpufreq
> 
> In the case of (1), we will have cpu OPPs and regulator registered
> as part of the device tree nodes, to ensure that omap-cpufreq
> and cpufreq-cpu0 don't conflict in managing the frequency of the
> same CPU, we should not permit omap-cpufreq to be probed.
> 
> In the case of (2), we will not have the cpufreq-cpu0 device, hence
> only omap-cpufreq will be active.
> 
> To eliminate this undesired these effects, we change omap-cpufreq
> driver to have it instantiated as a platform_driver and register
> "omap-cpufreq" device only when booted without device tree nodes on
> OMAP platforms.
> 
> This allows the following:
> a) Will only run on platforms that create the platform_device
>    "omap-cpufreq".
> b) Since the platform_device is registered only when device tree nodes
>    are *not* populated, omap-cpufreq driver does not conflict with
>    the usage of cpufreq-cpu0 driver which is used on OMAP platforms when
>    device tree nodes are present.
> 
> Inspired by commit 5553f9e26f6f49a93ba732fd222eac6973a4cf35
> (cpufreq: instantiate cpufreq-cpu0 as a platform_driver)
> 
> Cc: Kevin Hilman <khilman at linaro.org>
> Cc: Rajendra Nayak <rnayak at ti.com>
> Cc: Paul Walmsley <paul at pwsan.com>
> Cc: "Benoît Cousson" <b-cousson at ti.com>
> Cc: Jon Hunter <jon-hunter at ti.com>
> Cc: Keerthy <j-keerthy at ti.com>
> Cc: Santosh Shilimkar <santosh.shilimkar at ti.com>
> Cc: Shawn Guo <shawn.guo at linaro.org>
> [robherring2 at gmail.com: reported conflict of omap-cpufreq vs other
> driver in an non-device tree supported boot]
> Reported-by: Rob Herring <robherring2 at gmail.com>
> Signed-off-by: Nishanth Menon <nm at ti.com>
> Acked-by: Viresh Kumar <viresh.kumar at linaro.org>
> Signed-off-by: Kevin Hilman <khilman at linaro.org>
> ---
> Rafael, can you add this one for v3.10?  It applies on top the
> rest of your cpufreq changes and I've verified that the OMAP
> changes are OK and don't conflict with anything else we have
> queued for v3.10 on OMAP.
> 
> This patch was previously part of a 2-patch series, but the 
> other part is still in discussion, and this part can be merged
> independently.

Applied to my bleeding-edge branch and will go to linux-next after build testing.

Thanks,
Rafael


>  arch/arm/mach-omap2/pm.c       |  9 +++++++++
>  drivers/cpufreq/omap-cpufreq.c | 19 ++++++++++++++-----
>  2 files changed, 23 insertions(+), 5 deletions(-)
> 
> diff --git a/arch/arm/mach-omap2/pm.c b/arch/arm/mach-omap2/pm.c
> index 673a4c1..8d15f9a 100644
> --- a/arch/arm/mach-omap2/pm.c
> +++ b/arch/arm/mach-omap2/pm.c
> @@ -265,6 +265,12 @@ static void __init omap4_init_voltages(void)
>  	omap2_set_init_voltage("iva", "dpll_iva_m5x2_ck", "iva");
>  }
>  
> +static inline void omap_init_cpufreq(void)
> +{
> +	struct platform_device_info devinfo = { .name = "omap-cpufreq", };
> +	platform_device_register_full(&devinfo);
> +}
> +
>  static int __init omap2_common_pm_init(void)
>  {
>  	if (!of_have_populated_dt())
> @@ -294,6 +300,9 @@ int __init omap2_common_pm_late_init(void)
>  
>  		/* Smartreflex device init */
>  		omap_devinit_smartreflex();
> +
> +		/* cpufreq dummy device instantiation */
> +		omap_init_cpufreq();
>  	}
>  
>  #ifdef CONFIG_SUSPEND
> diff --git a/drivers/cpufreq/omap-cpufreq.c b/drivers/cpufreq/omap-cpufreq.c
> index 9128c07..d4f84b8 100644
> --- a/drivers/cpufreq/omap-cpufreq.c
> +++ b/drivers/cpufreq/omap-cpufreq.c
> @@ -25,6 +25,7 @@
>  #include <linux/opp.h>
>  #include <linux/cpu.h>
>  #include <linux/module.h>
> +#include <linux/platform_device.h>
>  #include <linux/regulator/consumer.h>
>  
>  #include <asm/smp_plat.h>
> @@ -252,7 +253,7 @@ static struct cpufreq_driver omap_driver = {
>  	.attr		= omap_cpufreq_attr,
>  };
>  
> -static int __init omap_cpufreq_init(void)
> +static int omap_cpufreq_probe(struct platform_device *pdev)
>  {
>  	mpu_dev = get_cpu_device(0);
>  	if (!mpu_dev) {
> @@ -280,12 +281,20 @@ static int __init omap_cpufreq_init(void)
>  	return cpufreq_register_driver(&omap_driver);
>  }
>  
> -static void __exit omap_cpufreq_exit(void)
> +static int omap_cpufreq_remove(struct platform_device *pdev)
>  {
> -	cpufreq_unregister_driver(&omap_driver);
> +	return cpufreq_unregister_driver(&omap_driver);
>  }
>  
> +static struct platform_driver omap_cpufreq_platdrv = {
> +	.driver = {
> +		.name	= "omap-cpufreq",
> +		.owner	= THIS_MODULE,
> +	},
> +	.probe		= omap_cpufreq_probe,
> +	.remove		= omap_cpufreq_remove,
> +};
> +module_platform_driver(omap_cpufreq_platdrv);
> +
>  MODULE_DESCRIPTION("cpufreq driver for OMAP SoCs");
>  MODULE_LICENSE("GPL");
> -module_init(omap_cpufreq_init);
> -module_exit(omap_cpufreq_exit);
> 
-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.