linux-kernel - RE: [PATCH v3 2/2] firmware: Keem Bay: Add support for Arm Trusted Firmware Service call

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Date:   Wed, 7 Oct 2020 13:52:42 +0000
From:   "Zulkifli, Muhammad Husaini" <muhammad.husaini.zulkifli@...el.com>
To:     Michal Simek <michal.simek@...inx.com>,
        "Hunter, Adrian" <adrian.hunter@...el.com>,
        "sudeep.holla@....com" <sudeep.holla@....com>,
        "ulf.hansson@...aro.org" <ulf.hansson@...aro.org>,
        "linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     "Raja Subramanian, Lakshmi Bai" 
        <lakshmi.bai.raja.subramanian@...el.com>,
        "Wan Mohamad, Wan Ahmad Zainie" 
        <wan.ahmad.zainie.wan.mohamad@...el.com>,
        "arnd@...db.de" <arnd@...db.de>
Subject: RE: [PATCH v3 2/2] firmware: Keem Bay: Add support for Arm Trusted
 Firmware Service call

Hi,

>-----Original Message-----
>From: Michal Simek <michal.simek@...inx.com>
>Sent: Wednesday, October 7, 2020 9:37 PM
>To: Zulkifli, Muhammad Husaini <muhammad.husaini.zulkifli@...el.com>;
>Michal Simek <michal.simek@...inx.com>; Hunter, Adrian
><adrian.hunter@...el.com>; sudeep.holla@....com; ulf.hansson@...aro.org;
>linux-mmc@...r.kernel.org; linux-arm-kernel@...ts.infradead.org; linux-
>kernel@...r.kernel.org
>Cc: Raja Subramanian, Lakshmi Bai <lakshmi.bai.raja.subramanian@...el.com>;
>Wan Mohamad, Wan Ahmad Zainie
><wan.ahmad.zainie.wan.mohamad@...el.com>; arnd@...db.de
>Subject: Re: [PATCH v3 2/2] firmware: Keem Bay: Add support for Arm Trusted
>Firmware Service call
>
>Hi,
>
>On 07. 10. 20 15:21, Zulkifli, Muhammad Husaini wrote:
>> Hi Michal,
>>
>> Thanks for the feedback. I replied inline
>>
>>> -----Original Message-----
>>> From: Michal Simek <michal.simek@...inx.com>
>>> Sent: Wednesday, October 7, 2020 4:20 PM
>>> To: Zulkifli, Muhammad Husaini <muhammad.husaini.zulkifli@...el.com>;
>>> Hunter, Adrian <adrian.hunter@...el.com>; michal.simek@...inx.com;
>>> sudeep.holla@....com; ulf.hansson@...aro.org;
>>> linux-mmc@...r.kernel.org; linux-arm-kernel@...ts.infradead.org;
>>> linux-kernel@...r.kernel.org
>>> Cc: Raja Subramanian, Lakshmi Bai
>>> <lakshmi.bai.raja.subramanian@...el.com>;
>>> Wan Mohamad, Wan Ahmad Zainie
>>> <wan.ahmad.zainie.wan.mohamad@...el.com>; arnd@...db.de
>>> Subject: Re: [PATCH v3 2/2] firmware: Keem Bay: Add support for Arm
>>> Trusted Firmware Service call
>>>
>>> Hi,
>>>
>>> 1. Keem Bay: in subject is wrong. Tools are working with it and you
>>> should just use keembay: instead.
>> Are you saying like this ?
>> Keem Bay: Add support for Arm Trusted Firmware Service call
>
>like this:
>firmware: keembay: Add support for Arm Trusted Firmware Service call
>
>>
>>>
>>> 2. This should come first before actual change to keep the tree bisectable.
>> Noted. Done the changes
>>>
>>> On 06. 10. 20 17:55, muhammad.husaini.zulkifli@...el.com wrote:
>>>> From: Muhammad Husaini Zulkifli
>>>> <muhammad.husaini.zulkifli@...el.com>
>>>>
>>>> Add header file to handle API function for device driver to
>>>> communicate with Arm Trusted Firmware.
>>>>
>>>> Signed-off-by: Muhammad Husaini Zulkifli
>>>> <muhammad.husaini.zulkifli@...el.com>
>>>> ---
>>>>  .../linux/firmware/intel/keembay_firmware.h   | 46 +++++++++++++++++++
>>>>  1 file changed, 46 insertions(+)
>>>>  create mode 100644 include/linux/firmware/intel/keembay_firmware.h
>>>>
>>>> diff --git a/include/linux/firmware/intel/keembay_firmware.h
>>>> b/include/linux/firmware/intel/keembay_firmware.h
>>>> new file mode 100644
>>>> index 000000000000..9adb8c87b788
>>>> --- /dev/null
>>>> +++ b/include/linux/firmware/intel/keembay_firmware.h
>>>> @@ -0,0 +1,46 @@
>>>> +/* SPDX-License-Identifier: GPL-2.0 */
>>>> +/*
>>>> + *  Intel Keembay SOC Firmware API Layer
>>>> + *
>>>> + *  Copyright (C) 2020-2021, Intel Corporation
>>>> + *
>>>> + *  Muhammad Husaini Zulkifli <Muhammad.Husaini.Zulkifli@...el.com>
>>>> + */
>>>> +
>>>> +#ifndef __FIRMWARE_KEEMBAY_SMC_H__
>>>> +#define __FIRMWARE_KEEMBAY_SMC_H__
>>>> +
>>>> +#include <linux/arm-smccc.h>
>>>> +
>>>> +/**
>>>
>>> This is not a kernel doc comment. Just use /*
>>>
>>>> + * This file defines API function that can be called by device
>>>> + driver in order to
>>>> + * communicate with Arm Trusted Firmware.
>>>> + */
>>>> +
>>>> +/* Setting for Keem Bay IO Pad Line Voltage Selection */
>>>> +#define KEEMBAY_SET_SD_VOLTAGE_FUNC_ID	0x8200ff26
>>>
>>> Sudeep: Don't we have any macros for composing these IDs?
>>> nit: IMHO composing these IDs from macros would make more sense to me.
>>>
>>>
>>>> +#define KEEMBAY_SET_1V8_VOLT		0x01
>>>
>>> 0x01 is just 1
>> Noted. Done the changes
>>>
>>>> +#define KEEMBAY_SET_3V3_VOLT		0x00
>>>
>>> 0x00 is just 0
>> Noted. Done the changes
>>>
>>>> +
>>>> +#if IS_ENABLED(CONFIG_HAVE_ARM_SMCCC_DISCOVERY)
>>>> +static int do_fw_invoke(u64 func_id, u64 arg0, u64 arg1) {
>>>> +	struct arm_smccc_res res;
>>>> +
>>>> +	arm_smccc_1_1_invoke(func_id, arg0, arg1, &res);
>>>> +
>>>> +	return res.a0;
>>>
>>> I am not big fan of this error propagation in case of failure.
>>>
>>> If smc fails you get via res.a0 SMCCC_RET_NOT_SUPPORTED which is
>>> defined as
>>> -1 which is based on errno-base.h defined as EPERM.
>>>
>>> That driver which Sudeep pointed you to is using EINVAL instead.
>>>
>>> It means I would add a code to check it.
>>
>> Yeah I changed to below line of codes. Is this Ok? Tested working.
>> int keembay_sd_voltage_selection(int volt)
>
>static inline here shouldn't hurt.
due to func() prototype " int keembay_sd_voltage_selection(int volt);" to solve warning issues by robot , I cannot set static inline here. 
Will observed below error:

error: static declaration of ‘keembay_sd_voltage_selection’ follows non-static declaration
 static inline int keembay_sd_voltage_selection(int volt).

>
>> {
>> 	struct arm_smccc_res res;
>>
>>
>	arm_smccc_1_1_invoke(ARM_SMCCC_SIP_KEEMBAY_SET_SD_VOLTAG
>E, volt, &res);
>> 	if ((int)res.a0 < 0)
>> 		return -EINVAL;
>>
>> 	return 0;
>> }
>
>This is fine.
>
>M