Re: [Patch v5 6/8] firmware: qcom: scm: Add support for ARM64 SoCs

Stephen Boyd
2016-06-02T22:28:45Z

On 05/12, Andy Gross wrote:
> +
> +#define MAX_QCOM_SCM_ARGS 10
> +#define MAX_QCOM_SCM_RETS 3
> +
> +#define QCOM_SCM_ARGS_IMPL(num, a, b, c, d, e, f, g, h, i, j, ...) (\
> + (((a) & 0x3) << 4) | \
> + (((b) & 0x3) << 6) | \
> + (((c) & 0x3) << 8) | \
> + (((d) & 0x3) << 10) | \
> + (((e) & 0x3) << 12) | \
> + (((f) & 0x3) << 14) | \
> + (((g) & 0x3) << 16) | \
> + (((h) & 0x3) << 18) | \
> + (((i) & 0x3) << 20) | \
> + (((j) & 0x3) << 22) | \
> + (num & 0xf))

Parenthesis around num?

> +
> +#define QCOM_SCM_ARGS(...) QCOM_SCM_ARGS_IMPL(__VA_ARGS__, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0)
> +
> +/**
> + * 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
> + */
> +struct qcom_scm_desc {
> + u32 arginfo;
> + u64 args[MAX_QCOM_SCM_ARGS];
> + struct arm_smccc_res res;
> +};

If we split the res from the descriptor structure we could make
the qcom_scm_desc const in qcom_scm_call(). We would have to add
another argument to the function though, not sure if this is a
big win idea, but just an idea to keep things "safer".

> +
> +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
> + * @dev: device
> + * @svc_id: service identifier
> + * @cmd_id: command identifier
> + * @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.
> +*/
> +static int qcom_scm_call(struct device *dev, u32 svc_id, u32 cmd_id,
> + struct qcom_scm_desc *desc)
> +{
> + int arglen = desc->arginfo & 0xf;
> + int retry_count = 0, i;
> + u32 fn_id = QCOM_SCM_FNID(svc_id, cmd_id);
> + u64 cmd, x5 = desc->args[FIRST_EXT_ARG_IDX];
> + dma_addr_t args_phys = 0;
> + void *args_virt = NULL;
> + size_t alloc_len;
> +
> + if (unlikely(arglen > N_REGISTER_ARGS)) {
> + alloc_len = N_EXT_QCOM_SCM_ARGS * sizeof(u64);
> + args_virt = kzalloc(PAGE_ALIGN(alloc_len), GFP_KERNEL);
> +
> + if (!args_virt)
> + return qcom_scm_remap_error(-ENOMEM);

Just return -ENOMEM here?

> +
> + if (qcom_smccc_convention == ARM_SMCCC_SMC_32) {
> + __le32 *args = args_virt;
> +
> + for (i = 0; i < N_EXT_QCOM_SCM_ARGS; i++)
> + args[i] = cpu_to_le32(desc->args[i +
> + FIRST_EXT_ARG_IDX]);
> + } else {
> + __le64 *args = args_virt;
> +
> + for (i = 0; i < N_EXT_QCOM_SCM_ARGS; i++)
> + args[i] = cpu_to_le64(desc->args[i +
> + FIRST_EXT_ARG_IDX]);
> + }
> +
> + args_phys = dma_map_single(dev, args_virt, alloc_len,
> + DMA_TO_DEVICE);
> +
> + if (dma_mapping_error(dev, args_phys)) {
> + kfree(args_virt);
> + return qcom_scm_remap_error(-ENOMEM);

Just return -ENOMEM here?

--
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