linux-kernel - Re: [PATCH v3 2/3] MIPS: Add CDMM bus support

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Date:	Thu, 26 Mar 2015 09:24:07 +0000
From:	James Hogan <james.hogan@...tec.com>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
CC:	Ralf Baechle <ralf@...ux-mips.org>, <linux-mips@...ux-mips.org>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 2/3] MIPS: Add CDMM bus support

On 25/03/15 22:03, Greg Kroah-Hartman wrote:
> On Wed, Mar 25, 2015 at 03:39:50PM +0000, James Hogan wrote:
>> Add MIPS Common Device Memory Map (CDMM) support in the form of a bus in
>> the standard Linux device model. Each device attached via CDMM is
>> discoverable via an 8-bit type identifier and may contain a number of
>> blocks of memory mapped registers in the CDMM region. IRQs are expected
>> to be handled separately.
>>
>> Due to the per-cpu (per-VPE for MT cores) nature of the CDMM devices,
>> all the driver callbacks take place from workqueues which are run on the
>> right CPU for the device in question, so that the driver doesn't need to
>> be as concerned about which CPU it is running on. Callbacks also exist
>> for when CPUs are taken offline, so that any per-CPU resources used by
>> the driver can be disabled so they don't get forcefully migrated. CDMM
>> devices are created as children of the CPU device they are attached to.
>>
>> Any existing CDMM configuration by the bootloader will be inherited,
>> however platforms wishing to enable CDMM should implement the weak
>> mips_cdmm_phys_base() function (see asm/cdmm.h) so that the bus driver
>> knows where it should put the CDMM region in the physical address space
>> if the bootloader hasn't already enabled it.
>>
>> A mips_cdmm_early_probe() function is also provided to allow early boot
>> or particularly low level code to set up the CDMM region and probe for a
>> specific device type, for example early console or KGDB IO drivers for
>> the EJTAG Fast Debug Channel (FDC) CDMM device.
>>
>> Signed-off-by: James Hogan <james.hogan@...tec.com>
>> Cc: Ralf Baechle <ralf@...ux-mips.org>
>> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
>> Cc: linux-mips@...ux-mips.org
>> ---
>> Changes in v3:
>> - Convert to use dev_groups rather than dev_attrs (GregKH).
>> - Rename mips_cdmm_attr_func() macro to CDMM_ATTR for consistency with
>>   other similar macro names I've seen around the kernel.
>> - Add modalias attribute.
>>
>> Changes in v2:
>> - Fix some checkpatch errors.
>> - Correct CDMM name in various places. It is "Common Device Memory Map",
>>   rather than "Common Device Mapped Memory" (which for some reason had
>>   got stuck in my head).
>> ---
>>  arch/mips/include/asm/cdmm.h      |  87 +++++
>>  drivers/bus/Kconfig               |  13 +
>>  drivers/bus/Makefile              |   1 +
>>  drivers/bus/mips_cdmm.c           | 716 ++++++++++++++++++++++++++++++++++++++
>>  include/linux/mod_devicetable.h   |   8 +
>>  scripts/mod/devicetable-offsets.c |   3 +
>>  scripts/mod/file2alias.c          |  16 +
>>  7 files changed, 844 insertions(+)
>>  create mode 100644 arch/mips/include/asm/cdmm.h
>>  create mode 100644 drivers/bus/mips_cdmm.c
> 
> Acked-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

Thanks Greg!

Cheers
James


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