linux-kernel - Re: [PATCH v2] firmware: qcom_scm: modify qcom_scm_set_download

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Message-ID: <3ca6d220-447e-0578-b525-3fb470be7edf@quicinc.com>
Date:   Fri, 3 Feb 2023 20:23:29 +0530
From:   Mukesh Ojha <quic_mojha@...cinc.com>
To:     Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
        <agross@...nel.org>, <andersson@...nel.org>,
        <konrad.dybcio@...aro.org>
CC:     <linux-arm-msm@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] firmware: qcom_scm: modify
 qcom_scm_set_download_mode()



On 2/3/2023 8:21 PM, Srinivas Kandagatla wrote:
> 
> 
> On 03/02/2023 10:17, Mukesh Ojha wrote:
>> Modify qcom_scm_set_download_mode() such that it can support
>> multiple modes. There is no functional change with this change.
>>
>> Signed-off-by: Mukesh Ojha <quic_mojha@...cinc.com>
>> ---
>> Changes in v2:
>>    - Stop changing legacy scm id for dload mode.
>>
>>   drivers/firmware/qcom_scm.c | 15 +++++++--------
>>   include/linux/qcom_scm.h    |  5 +++++
>>   2 files changed, 12 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/firmware/qcom_scm.c b/drivers/firmware/qcom_scm.c
>> index cdbfe54..6245b97 100644
>> --- a/drivers/firmware/qcom_scm.c
>> +++ b/drivers/firmware/qcom_scm.c
>> @@ -400,7 +400,7 @@ int qcom_scm_set_remote_state(u32 state, u32 id)
>>   }
>>   EXPORT_SYMBOL(qcom_scm_set_remote_state);
>> -static int __qcom_scm_set_dload_mode(struct device *dev, bool enable)
>> +static int __qcom_scm_set_dload_mode(struct device *dev, enum 
>> qcom_download_mode mode)
>>   {
>>       struct qcom_scm_desc desc = {
>>           .svc = QCOM_SCM_SVC_BOOT,
>> @@ -410,12 +410,12 @@ static int __qcom_scm_set_dload_mode(struct 
>> device *dev, bool enable)
>>           .owner = ARM_SMCCC_OWNER_SIP,
>>       };
>> -    desc.args[1] = enable ? QCOM_SCM_BOOT_SET_DLOAD_MODE : 0;
>> +    desc.args[1] = mode ? QCOM_SCM_BOOT_SET_DLOAD_MODE : 0;
> 
> I think this line should be:
> 
>      desc.args[1] = mode;
> 

Should be fine..for backward compatibility as we want to avoid what is 
passed to trust zone without check and since this is legacy code, i 
would like to avoid.

-Mukesh
> 
> --srini
> 
>>       return qcom_scm_call_atomic(__scm->dev, &desc, NULL);
>>   }
>> -static void qcom_scm_set_download_mode(bool enable)
>> +static void qcom_scm_set_download_mode(enum qcom_download_mode mode)
>>   {
>>       bool avail;
>>       int ret = 0;
>> @@ -424,10 +424,9 @@ static void qcom_scm_set_download_mode(bool enable)
>>                            QCOM_SCM_SVC_BOOT,
>>                            QCOM_SCM_BOOT_SET_DLOAD_MODE);
>>       if (avail) {
>> -        ret = __qcom_scm_set_dload_mode(__scm->dev, enable);
>> +        ret = __qcom_scm_set_dload_mode(__scm->dev, mode);
>>       } else if (__scm->dload_mode_addr) {
>> -        ret = qcom_scm_io_writel(__scm->dload_mode_addr,
>> -                enable ? QCOM_SCM_BOOT_SET_DLOAD_MODE : 0);
>> +        ret = qcom_scm_io_writel(__scm->dload_mode_addr, mode);
>>       } else {
>>           dev_err(__scm->dev,
>>               "No available mechanism for setting download mode\n");
>> @@ -1410,7 +1409,7 @@ static int qcom_scm_probe(struct platform_device 
>> *pdev)
>>        * disabled below by a clean shutdown/reboot.
>>        */
>>       if (download_mode)
>> -        qcom_scm_set_download_mode(true);
>> +        qcom_scm_set_download_mode(QCOM_DOWNLOAD_FULLDUMP);
>>       return 0;
>>   }
>> @@ -1419,7 +1418,7 @@ static void qcom_scm_shutdown(struct 
>> platform_device *pdev)
>>   {
>>       /* Clean shutdown, disable download mode to allow normal restart */
>>       if (download_mode)
>> -        qcom_scm_set_download_mode(false);
>> +        qcom_scm_set_download_mode(QCOM_DOWNLOAD_NODUMP);
>>   }
>>   static const struct of_device_id qcom_scm_dt_match[] = {
>> diff --git a/include/linux/qcom_scm.h b/include/linux/qcom_scm.h
>> index f833564..f9bc84e 100644
>> --- a/include/linux/qcom_scm.h
>> +++ b/include/linux/qcom_scm.h
>> @@ -14,6 +14,11 @@
>>   #define QCOM_SCM_CPU_PWR_DOWN_L2_OFF    0x1
>>   #define QCOM_SCM_HDCP_MAX_REQ_CNT    5
>> +enum qcom_download_mode {
>> +    QCOM_DOWNLOAD_NODUMP    = 0x00,
>> +    QCOM_DOWNLOAD_FULLDUMP  = 0x10,
>> +};
>> +
>>   struct qcom_scm_hdcp_req {
>>       u32 addr;
>>       u32 val;