linux-kernel - Re: [PATCH v1 1/1] scripts: dtc: mask flags bit when check i2c addr

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Date:   Tue, 3 Mar 2020 10:12:03 -0600
From:   Frank Rowand <frowand.list@...il.com>
To:     Rayagonda Kokatanur <rayagonda.kokatanur@...adcom.com>,
        Rob Herring <robh+dt@...nel.org>
Cc:     devicetree@...r.kernel.org,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "maintainer:BROADCOM BCM7XXX ARM ARCHITECTURE" 
        <bcm-kernel-feedback-list@...adcom.com>
Subject: Re: [PATCH v1 1/1] scripts: dtc: mask flags bit when check i2c addr

On 3/2/20 10:56 PM, Rayagonda Kokatanur wrote:
> On Fri, Feb 28, 2020 at 7:20 PM Rob Herring <robh+dt@...nel.org> wrote:
>>
>> On Fri, Feb 28, 2020 at 2:48 AM Rayagonda Kokatanur
>> <rayagonda.kokatanur@...adcom.com> wrote:
>>>
>>> Generally i2c addr should not be greater than 10-bit. The highest 2 bits
>>> are used for I2C_TEN_BIT_ADDRESS and I2C_OWN_SLAVE_ADDRESS. Need to mask
>>> these flags if check slave addr valid.
>>>
>>> Signed-off-by: Rayagonda Kokatanur <rayagonda.kokatanur@...adcom.com>
>>> ---
>>>  scripts/dtc/Makefile | 2 +-
>>>  scripts/dtc/checks.c | 5 +++++
>>>  2 files changed, 6 insertions(+), 1 deletion(-)
>>
>> dtc changes must be submitted against upstream dtc.
> 
> Please let me know link to clone the upstream dtc branch.

Info about the dtc upstream project:

   https://elinux.org/Device_Tree_Reference#dtc_.28upstream_project.29

And the mail list to submit the patch to:

   https://elinux.org/Device_Tree_Reference#Device-tree_Compiler_and_Tools_Mailing_List

-Frank

>>
>>
>>> diff --git a/scripts/dtc/Makefile b/scripts/dtc/Makefile
>>> index 3acbb410904c..c5e8d6a9e73c 100644
>>> --- a/scripts/dtc/Makefile
>>> +++ b/scripts/dtc/Makefile
>>> @@ -9,7 +9,7 @@ dtc-objs        := dtc.o flattree.o fstree.o data.o livetree.o treesource.o \
>>>  dtc-objs       += dtc-lexer.lex.o dtc-parser.tab.o
>>>
>>>  # Source files need to get at the userspace version of libfdt_env.h to compile
>>> -HOST_EXTRACFLAGS := -I $(srctree)/$(src)/libfdt
>>> +HOST_EXTRACFLAGS := -I $(srctree)/$(src)/libfdt -I$(srctree)/tools/include
>>>
>>>  ifeq ($(shell pkg-config --exists yaml-0.1 2>/dev/null && echo yes),)
>>>  ifneq ($(CHECK_DTBS),)
>>> diff --git a/scripts/dtc/checks.c b/scripts/dtc/checks.c
>>> index 756f0fa9203f..17c9ed4137b5 100644
>>> --- a/scripts/dtc/checks.c
>>> +++ b/scripts/dtc/checks.c
>>> @@ -3,6 +3,7 @@
>>>   * (C) Copyright David Gibson <dwg@....ibm.com>, IBM Corporation.  2007.
>>>   */
>>>
>>> +#include <linux/bits.h>
>>
>> Not a UAPI header not that that would be much better as dtc also builds on Mac.
>>
>>>  #include "dtc.h"
>>>  #include "srcpos.h"
>>>
>>> @@ -17,6 +18,9 @@
>>>  #define TRACE(c, fmt, ...)     do { } while (0)
>>>  #endif
>>>
>>> +#define I2C_TEN_BIT_ADDRESS    BIT(31)
>>> +#define I2C_OWN_SLAVE_ADDRESS  BIT(30)
>>> +
>>>  enum checkstatus {
>>>         UNCHECKED = 0,
>>>         PREREQ,
>>> @@ -1048,6 +1052,7 @@ static void check_i2c_bus_reg(struct check *c, struct dt_info *dti, struct node
>>>
>>>         for (len = prop->val.len; len > 0; len -= 4) {
>>>                 reg = fdt32_to_cpu(*(cells++));
>>> +               reg &= ~(I2C_OWN_SLAVE_ADDRESS | I2C_TEN_BIT_ADDRESS);
>>
>> I'd just mask the top byte so we don't have to update on the next flag we add.
> Do you mean something like this, shown below ?
> reg &= 0xFFFF_FC000;
> 
>>
>> Rob
>