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 13:21:14 +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 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

>
>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)
{
	struct arm_smccc_res res;

	arm_smccc_1_1_invoke(ARM_SMCCC_SIP_KEEMBAY_SET_SD_VOLTAGE, volt, &res);
	if ((int)res.a0 < 0)
		return -EINVAL;

	return 0;
}

>
>
>> +}
>> +
>> +int keembay_sd_voltage_selection(int volt)
>
>as was reported by robot
Added the func prototype. 
int keembay_sd_voltage_selection(int volt);
No error observed after that.
>
>> +{
>> +	return do_fw_invoke(KEEMBAY_SET_SD_VOLTAGE_FUNC_ID, volt, 0); }
>> +#else static inline int keembay_sd_voltage_selection(int volt) {
>> +	return -ENODEV;
>> +}
>> +#endif
>> +
>> +#endif /* __FIRMWARE_KEEMBAY_SMC_H__ */
>>
>
>M