[PATCH 13/16] drivers: misc: add ARM CCI support

[Santosh Shilimkar]

On Saturday 12 January 2013 12:52 AM, Nicolas Pitre wrote:
> On Fri, 11 Jan 2013, Santosh Shilimkar wrote:
>
>> On Thursday 10 January 2013 05:50 AM, Nicolas Pitre wrote:
>>> From: Lorenzo Pieralisi <lorenzo.pieralisi at arm.com>
>>>
>>> On ARM multi-cluster systems coherency between cores running on
>>> different clusters is managed by the cache-coherent interconnect (CCI).
>>> It allows broadcasting of TLB invalidates and memory barriers and it
>>> guarantees cache coherency at system level.
>>>
>>> This patch enables the basic infrastructure required in Linux to
>>> handle and programme the CCI component. The first implementation is
>>> based on a platform device, its relative DT compatible property and
>>> a simple programming interface.
>>>
>>> Signed-off-by: Nicolas Pitre <nico at linaro.org>
>>> ---
>>>    drivers/misc/Kconfig    |   3 ++
>>>    drivers/misc/Makefile   |   1 +
>>>    drivers/misc/arm-cci.c  | 107
>>> ++++++++++++++++++++++++++++++++++++++++++++++++
>>>    include/linux/arm-cci.h |  30 ++++++++++++++
>> How about 'drivers/bus/' considering CCI is an interconnect bus (though
>> for coherency)
>
> Yes, I like that better.
>
Great.

>>>    4 files changed, 141 insertions(+)
>>>    create mode 100644 drivers/misc/arm-cci.c
>>>    create mode 100644 include/linux/arm-cci.h
>>>
>>> diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
>>> index b151b7c1bd..30d5be1ad2 100644
>>> --- a/drivers/misc/Kconfig
>>> +++ b/drivers/misc/Kconfig
>>> @@ -499,6 +499,9 @@ config USB_SWITCH_FSA9480
>>>    	  stereo and mono audio, video, microphone and UART data to use
>>>    	  a common connector port.
>>>
>>> +config ARM_CCI
>> You might want add depends on ARM big.LITTTLE otherwise it will
>> break build for other arch's with random configurations.
>
> As far as this patch goes, this is buildable on other architectures too.
> The next patch changes that though.
>
Thanks.

>> [..]
>>
>>> diff --git a/drivers/misc/arm-cci.c b/drivers/misc/arm-cci.c
>>> new file mode 100644
>>> index 0000000000..f329c43099
>>> --- /dev/null
>>> +++ b/drivers/misc/arm-cci.c
>>> @@ -0,0 +1,107 @@
>>> +/*
>>> + * CCI support
>>> + *
>>> + * Copyright (C) 2012 ARM Ltd.
>>> + * Author: Lorenzo Pieralisi <lorenzo.pieralisi at arm.com>
>>> + *
>>> + * This program is free software; you can redistribute it and/or modify
>>> + * it under the terms of the GNU General Public License version 2 as
>>> + * published by the Free Software Foundation.
>>> + *
>>> + * This program is distributed "as is" WITHOUT ANY WARRANTY of any
>>> + * kind, whether express or implied; without even the implied warranty
>>> + * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
>>> + * GNU General Public License for more details.
>>> + */
>>> +
>>> +#include <linux/device.h>
>>> +#include <linux/io.h>
>>> +#include <linux/module.h>
>>> +#include <linux/platform_device.h>
>>> +#include <linux/slab.h>
>>> +#include <linux/arm-cci.h>
>>> +
>>> +#define CCI400_EAG_OFFSET       0x4000
>>> +#define CCI400_KF_OFFSET        0x5000
>>> +
>>> +#define DRIVER_NAME	"CCI"
>>> +struct cci_drvdata {
>>> +	void __iomem *baseaddr;
>>> +	spinlock_t lock;
>>> +};
>>> +
>>> +static struct cci_drvdata *info;
>>> +
>>> +void disable_cci(int cluster)
>>> +{
>>> +	u32 cci_reg = cluster ? CCI400_KF_OFFSET : CCI400_EAG_OFFSET;
>>> +	writel_relaxed(0x0, info->baseaddr	+ cci_reg);
>>> +
>>> +	while (readl_relaxed(info->baseaddr + 0xc) & 0x1)
>>> +			;
>>> +}
>>> +EXPORT_SYMBOL_GPL(disable_cci);
>>> +
>> Is more functionality going to be added for CCI driver. Having this
>> much of driver code for just a disable_cci() functions seems like
>> overkill.
>
> Yes.  More code will appear here to provide pmu functionalities, etc.
>
Good to know.

Regards,
Santosh