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Subject[PATCH v3 1/4] firmware: qcom_scm-64: Add atomic version of qcom_scm_call
Date
There are scnenarios where drivers are required to make a
scm call in atomic context, such as in one of the qcom's
arm-smmu-500 errata [1].

[1] ("https://source.codeaurora.org/quic/la/kernel/msm-4.9/commit/
drivers/iommu/arm-smmu.c?h=CogSystems-msm-49/
msm-4.9&id=da765c6c75266b38191b38ef086274943f353ea7")

Signed-off-by: Vivek Gautam <vivek.gautam@codeaurora.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
---
drivers/firmware/qcom_scm-64.c | 136 ++++++++++++++++++++++++++++-------------
1 file changed, 92 insertions(+), 44 deletions(-)

diff --git a/drivers/firmware/qcom_scm-64.c b/drivers/firmware/qcom_scm-64.c
index 91d5ad7cf58b..b6dca32c5ac4 100644
--- a/drivers/firmware/qcom_scm-64.c
+++ b/drivers/firmware/qcom_scm-64.c
@@ -62,32 +62,71 @@ static DEFINE_MUTEX(qcom_scm_lock);
#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,
- const struct qcom_scm_desc *desc,
- struct arm_smccc_res *res)
+static void __qcom_scm_call_do(const struct qcom_scm_desc *desc,
+ struct arm_smccc_res *res, u32 fn_id,
+ u64 x5, u32 type)
+{
+ u64 cmd;
+ struct arm_smccc_quirk quirk = {.id = ARM_SMCCC_QUIRK_QCOM_A6};
+
+ cmd = ARM_SMCCC_CALL_VAL(type, qcom_smccc_convention,
+ ARM_SMCCC_OWNER_SIP, fn_id);
+
+ quirk.state.a6 = 0;
+
+ do {
+ arm_smccc_smc_quirk(cmd, desc->arginfo, desc->args[0],
+ desc->args[1], desc->args[2], x5,
+ quirk.state.a6, 0, res, &quirk);
+
+ if (res->a0 == QCOM_SCM_INTERRUPTED)
+ cmd = res->a0;
+
+ } while (res->a0 == QCOM_SCM_INTERRUPTED);
+}
+
+static void qcom_scm_call_do(const struct qcom_scm_desc *desc,
+ struct arm_smccc_res *res, u32 fn_id,
+ u64 x5, bool atomic)
+{
+ int retry_count = 0;
+
+ if (!atomic) {
+ do {
+ mutex_lock(&qcom_scm_lock);
+
+ __qcom_scm_call_do(desc, res, fn_id, x5,
+ ARM_SMCCC_STD_CALL);
+
+ mutex_unlock(&qcom_scm_lock);
+
+ if (res->a0 == QCOM_SCM_V2_EBUSY) {
+ if (retry_count++ > QCOM_SCM_EBUSY_MAX_RETRY)
+ break;
+ msleep(QCOM_SCM_EBUSY_WAIT_MS);
+ }
+ } while (res->a0 == QCOM_SCM_V2_EBUSY);
+ } else {
+ __qcom_scm_call_do(desc, res, fn_id, x5, ARM_SMCCC_FAST_CALL);
+ }
+}
+
+static int ___qcom_scm_call(struct device *dev, u32 svc_id, u32 cmd_id,
+ const struct qcom_scm_desc *desc,
+ struct arm_smccc_res *res, bool atomic)
{
int arglen = desc->arginfo & 0xf;
- int retry_count = 0, i;
+ int i;
u32 fn_id = QCOM_SCM_FNID(svc_id, cmd_id);
- u64 cmd, x5 = desc->args[FIRST_EXT_ARG_IDX];
+ u64 x5 = desc->args[FIRST_EXT_ARG_IDX];
dma_addr_t args_phys = 0;
void *args_virt = NULL;
size_t alloc_len;
- struct arm_smccc_quirk quirk = {.id = ARM_SMCCC_QUIRK_QCOM_A6};
+ gfp_t flag = atomic ? GFP_ATOMIC : GFP_KERNEL;

if (unlikely(arglen > N_REGISTER_ARGS)) {
alloc_len = N_EXT_QCOM_SCM_ARGS * sizeof(u64);
- args_virt = kzalloc(PAGE_ALIGN(alloc_len), GFP_KERNEL);
+ args_virt = kzalloc(PAGE_ALIGN(alloc_len), flag);

if (!args_virt)
return -ENOMEM;
@@ -117,33 +156,7 @@ static int qcom_scm_call(struct device *dev, u32 svc_id, u32 cmd_id,
x5 = 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);
-
- quirk.state.a6 = 0;
-
- do {
- arm_smccc_smc_quirk(cmd, desc->arginfo, desc->args[0],
- desc->args[1], desc->args[2], x5,
- quirk.state.a6, 0, res, &quirk);
-
- if (res->a0 == QCOM_SCM_INTERRUPTED)
- cmd = res->a0;
-
- } while (res->a0 == QCOM_SCM_INTERRUPTED);
-
- mutex_unlock(&qcom_scm_lock);
-
- if (res->a0 == QCOM_SCM_V2_EBUSY) {
- if (retry_count++ > QCOM_SCM_EBUSY_MAX_RETRY)
- break;
- msleep(QCOM_SCM_EBUSY_WAIT_MS);
- }
- } while (res->a0 == QCOM_SCM_V2_EBUSY);
+ qcom_scm_call_do(desc, res, fn_id, x5, atomic);

if (args_virt) {
dma_unmap_single(dev, args_phys, alloc_len, DMA_TO_DEVICE);
@@ -156,6 +169,41 @@ static int qcom_scm_call(struct device *dev, u32 svc_id, u32 cmd_id,
return 0;
}

+/**
+ * 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,
+ const struct qcom_scm_desc *desc,
+ struct arm_smccc_res *res)
+{
+ return ___qcom_scm_call(dev, svc_id, cmd_id, desc, res, false);
+}
+
+/**
+ * qcom_scm_call_atomic() - atomic variation of qcom_scm_call()
+ * @dev: device
+ * @svc_id: service identifier
+ * @cmd_id: command identifier
+ * @desc: Descriptor structure containing arguments and return values
+ * @res: Structure containing results from SMC/HVC call
+ *
+ * Sends a command to the SCM and waits for the command to finish processing.
+ * This should be called in atomic context only.
+ */
+static int qcom_scm_call_atomic(struct device *dev, u32 svc_id, u32 cmd_id,
+ const struct qcom_scm_desc *desc,
+ struct arm_smccc_res *res)
+{
+ return ___qcom_scm_call(dev, svc_id, cmd_id, desc, res, true);
+}
+
/**
* qcom_scm_set_cold_boot_addr() - Set the cold boot address for cpus
* @entry: Entry point function for the cpus
--
QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member
of Code Aurora Forum, hosted by The Linux Foundation
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