Date: Fri, 22 Apr 2016 16:41:05 -0700
From: Bjorn Andersson <bjorn.andersson@linaro.org>
To: Andy Gross <andy.gross@linaro.org>
Cc: linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org,
        Stephen Boyd <sboyd@codeaurora.org>, devicetree@vger.kernel.org,
        Bjorn Andersson <bjorn.andersson@sonymobile.com>,
        jilai wang <jilaiw@codeaurora.org>, Kumar Gala <galak@codeaurora.org>
Subject: Re: [PATCH 4/8] firmware: qcom: scm: Add support for ARM64 SoCs
Message-ID: <20160422234105.GH3202@tuxbot>
References: <1461363432-5730-1-git-send-email-andy.gross@linaro.org>
 <1461363432-5730-5-git-send-email-andy.gross@linaro.org>
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On Fri 22 Apr 15:17 PDT 2016, Andy Gross wrote:

[..]
> diff --git a/drivers/firmware/qcom_scm-64.c b/drivers/firmware/qcom_scm-64.c
[..]
> +
> +/**
> + * struct qcom_scm_desc
> + * @arginfo: Metadata describing the arguments in args[]
> + * @args: The array of arguments for the secure syscall
> + * @res: The values returned by the secure syscall
> + * @extra_args_virt: The buffer containing extra arguments
> +		   (that don't fit in available registers)
> + * @extra_args_phys: The physical address of the extra arguments

@alloc_size

> + */
> +struct qcom_scm_desc {
> +	u32 arginfo;
> +	u64 args[MAX_QCOM_SCM_ARGS];
> +	struct arm_smccc_res res;
> +
> +	/* private */
> +	void *extra_args_virt;
> +	dma_addr_t extra_args_phys;
> +	size_t alloc_size;
> +};
> +
> +static u64 qcom_smccc_convention = -1;
> +static DEFINE_MUTEX(qcom_scm_lock);
> +
> +#define QCOM_SCM_EBUSY_WAIT_MS 30
> +#define QCOM_SCM_EBUSY_MAX_RETRY 20
> +
> +#define N_EXT_QCOM_SCM_ARGS 7
> +#define FIRST_EXT_ARG_IDX 3
> +#define N_REGISTER_ARGS (MAX_QCOM_SCM_ARGS - N_EXT_QCOM_SCM_ARGS + 1)
> +
> +/**
> + * qcom_scm_call() - Invoke a syscall in the secure world
> + * @svc_id: service identifier
> + * @cmd_id: command identifier
> + * @fn_id: The function ID for this syscall
> + * @desc: Descriptor structure containing arguments and return values
> + *
> + * Sends a command to the SCM and waits for the command to finish processing.
> + * This should *only* be called in pre-emptible context.
> + *
> +*/

Extra empty line in comment and odd indentation.

> +static int qcom_scm_call(u32 svc_id, u32 cmd_id, struct qcom_scm_desc *desc)
> +{
> +	int arglen = desc->arginfo & 0xf;
> +	int ret, retry_count = 0, i;
> +	u32 fn_id = QCOM_SCM_FNID(svc_id, cmd_id);
> +	u64 cmd, x5 = desc->args[FIRST_EXT_ARG_IDX];
> +
> +	if (unlikely(arglen > N_REGISTER_ARGS)) {
> +		desc->alloc_size = N_EXT_QCOM_SCM_ARGS * sizeof(u64);
> +		desc->extra_args_virt =

alloc_size, extra_args_virt and extra_args_phys doesn't seem to outlive
this function, can't they be made local variable?

> +			qcom_scm_alloc_buffer(desc->alloc_size,
> +						 &desc->extra_args_phys,
> +						 GFP_KERNEL);
> +		if (!desc->extra_args_virt)
> +			return qcom_scm_remap_error(-ENOMEM);
> +
> +		if (qcom_smccc_convention == ARM_SMCCC_SMC_32) {
> +			u32 *args = desc->extra_args_virt;
> +
> +			for (i = 0; i < N_EXT_QCOM_SCM_ARGS; i++)
> +				args[i] = desc->args[i + FIRST_EXT_ARG_IDX];
> +		} else {
> +			u64 *args = desc->extra_args_virt;
> +
> +			for (i = 0; i < N_EXT_QCOM_SCM_ARGS; i++)
> +				args[i] = desc->args[i + FIRST_EXT_ARG_IDX];
> +		}
> +
> +		x5 = desc->extra_args_phys;
> +	}
> +
> +	do {
> +		mutex_lock(&qcom_scm_lock);
> +
> +		cmd = ARM_SMCCC_CALL_VAL(ARM_SMCCC_STD_CALL,
> +					 qcom_smccc_convention,
> +					 ARM_SMCCC_OWNER_SIP, fn_id);
> +
> +		do {
> +			arm_smccc_smc(cmd, arglen, desc->args[0], desc->args[1],
> +				      desc->args[2], x5, 0, 0, &desc->res);
> +		} while (desc->res.a0 == QCOM_SCM_INTERRUPTED);
> +
> +		mutex_unlock(&qcom_scm_lock);
> +
> +		if (desc->res.a0 == QCOM_SCM_V2_EBUSY) {
> +			if (retry_count++ > QCOM_SCM_EBUSY_MAX_RETRY)
> +				break;
> +			msleep(QCOM_SCM_EBUSY_WAIT_MS);
> +		}
> +	}  while (desc->res.a0 == QCOM_SCM_V2_EBUSY);
> +
> +	if (desc->extra_args_virt)
> +		qcom_scm_free_buffer(desc->alloc_size, desc->extra_args_virt,
> +				     desc->extra_args_phys);
> +
> +	if (desc->res.a0 < 0)
> +		return qcom_scm_remap_error(ret);
> +
> +	return 0;
> +}
>  
>  /**
>   * qcom_scm_set_cold_boot_addr() - Set the cold boot address for cpus
> @@ -50,14 +186,68 @@ int __qcom_scm_set_warm_boot_addr(void *entry, const cpumask_t *cpus)
>   */
>  void __qcom_scm_cpu_power_down(u32 flags)
>  {
> +	return;

We can't have this empty?

>  }
>  
>  int __qcom_scm_is_call_available(u32 svc_id, u32 cmd_id)
>  {
> -	return -ENOTSUPP;
> +	int ret;
> +	struct qcom_scm_desc desc = {0};
> +
> +	desc.arginfo = QCOM_SCM_ARGS(1);
> +	desc.args[0] = QCOM_SCM_FNID(svc_id, cmd_id) |

Are we not playing the endian game om arm64?

> +			(ARM_SMCCC_OWNER_SIP << ARM_SMCCC_OWNER_SHIFT);
> +
> +	ret = qcom_scm_call(QCOM_SCM_SVC_INFO, QCOM_IS_CALL_AVAIL_CMD,
> +			    &desc);
> +
> +	if (ret)
> +		return ret;
> +
> +	return desc.res.a1;

We use the following construct elsewhere in scm:

	return ret ? : desc.res.a1;

>  }
>  
[..]
> diff --git a/drivers/firmware/qcom_scm.c b/drivers/firmware/qcom_scm.c
> index 8e1eeb8..7d7b12b 100644
[..]
>  
> +static void qcom_scm_init(void)
> +{
> +	__qcom_scm_init();
> +}
> +
>  static int qcom_scm_probe(struct platform_device *pdev)
>  {
>  	struct qcom_scm *scm;
> @@ -208,6 +213,8 @@ static int qcom_scm_probe(struct platform_device *pdev)
>  	__scm = scm;
>  	__scm->dev = &pdev->dev;
>  
> +	qcom_scm_init();
> +

Why don't you call __qcom_scm_init() directly here?

>  	return 0;
>  }
>  
> diff --git a/drivers/firmware/qcom_scm.h b/drivers/firmware/qcom_scm.h
[..]
> +#define QCOM_SCM_V2_EBUSY	-12
>  #define QCOM_SCM_ENOMEM		-5
>  #define QCOM_SCM_EOPNOTSUPP	-4
>  #define QCOM_SCM_EINVAL_ADDR	-3
> @@ -56,6 +58,8 @@ static inline int qcom_scm_remap_error(int err)
>  		return -EOPNOTSUPP;
>  	case QCOM_SCM_ENOMEM:
>  		return -ENOMEM;
> +	case QCOM_SCM_V2_EBUSY:
> +		return err;

I don't think return -ENOMEM is the right thing to do here.

>  	}
>  	return -EINVAL;
>  }

Regards,
Bjorn