[PATCH v2 3/3] arm: exynos: Add /dev/bL_status user interface on Exynos5420

[Dave Martin]

On Tue, Apr 22, 2014 at 11:47:37AM +0530, Abhilash Kesavan wrote:
> Add a user interface to check the core and cluster status on
> Exynos5420. This can be utilized while debugging mcpm issues.
> cat /dev/bL_status will show the current power status of all
> the 8 cores along with the cluster.

You might want to make this conditional on some Kconfig option.
Like any debug interface, there is a risk that it will be misused if
people assume it will always be available.

I think debugfs is better for this kind of thing rather than creating a
new misc device.


If the SoC-specific parts can be factored out, maybe this would be
usable on other SoCs too.  The information can also be made richer,
with displaying the MCPM state of each CPU and cluster as well as
the hardware state of each.

Just a thought.

Cheers
---Dave


> 
> Signed-off-by: Thomas Abraham <thomas.ab at samsung.com>
> Signed-off-by: Inderpal Singh <inderpal.s at samsung.com>
> Signed-off-by: Andrew Bresticker <abrestic at chromium.org>
> Signed-off-by: Abhilash Kesavan <a.kesavan at samsung.com>
> ---
>  arch/arm/mach-exynos/mcpm-exynos.c |   64 ++++++++++++++++++++++++++++++++++++
>  1 file changed, 64 insertions(+)
> 
> diff --git a/arch/arm/mach-exynos/mcpm-exynos.c b/arch/arm/mach-exynos/mcpm-exynos.c
> index 49b9031..6c74c82 100644
> --- a/arch/arm/mach-exynos/mcpm-exynos.c
> +++ b/arch/arm/mach-exynos/mcpm-exynos.c
> @@ -293,6 +293,53 @@ static void __init exynos_mcpm_usage_count_init(void)
>  	cpu_use_count[cpu][cluster] = 1;
>  }
>  
> +static size_t bL_check_status(char *info)
> +{
> +	size_t len = 0;
> +	int i;
> +
> +	len += sprintf(&info[len], "\t0 1 2 3 L2\n");
> +	len += sprintf(&info[len], "[A15]   ");
> +	for (i = 0; i < 4; i++) {
> +		len += sprintf(&info[len], "%d ",
> +			(readl(EXYNOS_ARM_CORE_STATUS(i)) & 0x3) == 3 ? 1 : 0);
> +	}
> +	len += sprintf(&info[len], "%d\n",
> +			(readl(EXYNOS_COMMON_STATUS(0)) & 0x3) == 3 ? 1 : 0);
> +
> +	len += sprintf(&info[len], "[A7]    ");
> +	for (i = 4; i < 8; i++)
> +		len += sprintf(&info[len], "%d ",
> +			(readl(EXYNOS_ARM_CORE_STATUS(i)) & 0x3) == 3 ? 1 : 0);
> +	len += sprintf(&info[len], "%d\n\n",
> +			(readl(EXYNOS_COMMON_STATUS(1)) & 0x3) == 3 ? 1 : 0);
> +
> +	return len;
> +}
> +
> +static ssize_t bL_status_read(struct file *file, char __user *buf,
> +			size_t len, loff_t *pos)
> +{
> +	size_t count = 0;
> +	char info[100];
> +
> +	count = bL_check_status(info);
> +	if (count < 0)
> +		return -EINVAL;
> +
> +	return simple_read_from_buffer(buf, len, pos, info, count);
> +}
> +
> +static const struct file_operations bL_status_fops = {
> +	.read		= bL_status_read,
> +};
> +
> +static struct miscdevice bL_status_device = {
> +	MISC_DYNAMIC_MINOR,
> +	"bL_status",
> +	&bL_status_fops
> +};
> +
>  /*
>   * Enable cluster-level coherency, in preparation for turning on the MMU.
>   */
> @@ -343,3 +390,20 @@ static int __init exynos_mcpm_init(void)
>  }
>  
>  early_initcall(exynos_mcpm_init);
> +
> +static int __init exynos_bl_status_init(void)
> +{
> +	int ret;
> +
> +	if (!soc_is_exynos5420())
> +		return -ENODEV;
> +
> +	ret = misc_register(&bL_status_device);
> +	if (ret) {
> +		pr_info("bl_status not available\n");
> +		return ret;
> +	}
> +	return 0;
> +}
> +
> +late_initcall(exynos_bl_status_init);
> -- 
> 1.7.9.5
> 
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel at lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel