[PATCH v19 2/7] firmware: arm_rmm: Check for RMI support at init

[Suzuki K Poulose]

On 25/09/2026 06:43, Gavin Shan wrote:
> On 9/24/26 11:51 PM, Suzuki K Poulose wrote:
>> From: Steven Price <steven.price at arm.com>
>>
>> Query the RMI version number and check if it is a compatible version.
>> The first two feature registers are read and exposed for future code to
>> use.
>>
>> We only support this for Little Endian kernels, the Big Endian kernel
>> support is anyway marked BROKEN and is being removed.
>>
>> Signed-off-by: Steven Price <steven.price at arm.com>
>> Co-developed-by: Suzuki K Poulose <suzuki.poulose at arm.com>
>> Signed-off-by: Suzuki K Poulose <suzuki.poulose at arm.com>
>> ---
>> v19:
>>   * Read all implemented RmiFeatureRegisters - 5
>>   * Use ARRAY_SIZE(rmi_feat_reg_cache) for the loop in 
>> rmi_read_features()
>>   * Fold rmi_features() into rmi_read_features
>>   * Fix comment for rmi_smccc_invoke()
>>   * Drop default y
>>   * Add retry for RMI_BLOCKED and return to caller
>> v18:
>>   * Always use arm_smccc_1_2_invoke() for all RMIs making sure the 
>> unsused
>>     parameters are 0 - Sashiko
>>   * Move rmi_features() calls away from the arm-rmi-cmds.h to rmi.c - 
>> Gavin
>> v17:
>>   * Rename ARM_RMM to ARM_RMM_RMI to make it easier to add Guest 
>> facing RSI
>>     support, which is also in progress
>> v16:
>>   * Update Kconfig text to include PCIe TDISP.
>>   * Export rmi_feat_reg() here rather than in a later commit.
>> v15:
>>   * The code is moved again, this time into the 'firmware' directory.
>> v14:
>>   * This moves the basic RMI setup into the 'kernel' directory. This is
>>     because RMI will be used for some features outside of KVM so should
>>     be available even if KVM isn't compiled in.
>> ---
>>   arch/arm64/Kconfig                |   1 +
>>   arch/arm64/kernel/cpufeature.c    |   1 +
>>   drivers/firmware/Kconfig          |   1 +
>>   drivers/firmware/Makefile         |   1 +
>>   drivers/firmware/arm_rmm/Kconfig  |  25 +++++++
>>   drivers/firmware/arm_rmm/Makefile |   2 +
>>   drivers/firmware/arm_rmm/rmi.c    | 109 ++++++++++++++++++++++++++++++
>>   include/linux/arm-rmi-cmds.h      |  48 +++++++++++++
>>   8 files changed, 188 insertions(+)
>>   create mode 100644 drivers/firmware/arm_rmm/Kconfig
>>   create mode 100644 drivers/firmware/arm_rmm/Makefile
>>   create mode 100644 drivers/firmware/arm_rmm/rmi.c
>>   create mode 100644 include/linux/arm-rmi-cmds.h
>>
> 
> [...]
> 
>> diff --git a/drivers/firmware/arm_rmm/Makefile b/drivers/firmware/ 
>> arm_rmm/Makefile
>> new file mode 100644
>> index 0000000000000..65171988fdcae
>> --- /dev/null
>> +++ b/drivers/firmware/arm_rmm/Makefile
>> @@ -0,0 +1,2 @@
>> +
>> +obj-$(CONFIG_ARM_RMM_RMI)    = rmi.o
> 
> Unnecessary blank line at the top in Makefile. Besides, why doesn't this 
> come
> as below? :)
> 
> obj-$(CONFIG_ARM_RMM_RMI)    += rmi.o

Good point, now that the ARM_RMM_RSI is also getting merged there.

Cheers
Suzuki

> 
> Thanks,
> Gavin
> 
>