firmware: qcom_scm: Dynamically support SMCCC and legacy conventions

Dynamically support SMCCCC and legacy conventions by detecting which
convention to use at runtime. qcom_scm_call_atomic and qcom_scm_call can
then be moved in qcom_scm.c and use underlying convention backend as
appropriate. Thus, rename qcom_scm-64,-32 to reflect that they are
backends for -smc and -legacy, respectively.

Also add support for making SCM calls earlier than when SCM driver
probes to support use cases such as qcom_scm_set_cold_boot_addr. Support
is added by lazily initializing the convention and guarding the query
with a spin lock.  The limitation of these early SCM calls is that they
cannot use DMA, as in the case of >4 arguments for SMC convention and
any non-atomic call for legacy convention.

Tested-by: Brian Masney <masneyb@onstation.org> # arm32
Tested-by: Stephan Gerhold <stephan@gerhold.net>
Signed-off-by: Elliot Berman <eberman@codeaurora.org>
Link: https://lore.kernel.org/r/1578431066-19600-18-git-send-email-eberman@codeaurora.org
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

1 files changed, 151 insertions, 0 deletions

diff --git a/drivers/firmware/qcom_scm-smc.c b/drivers/firmware/qcom_scm-smc.c
new file mode 100644
index 000000000000..497c13ba98d6
--- /dev/null
+++ b/drivers/firmware/qcom_scm-smc.c
@@ -0,0 +1,151 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright (c) 2015,2019 The Linux Foundation. All rights reserved.
+ */
+
+#include <linux/io.h>
+#include <linux/errno.h>
+#include <linux/delay.h>
+#include <linux/mutex.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+#include <linux/qcom_scm.h>
+#include <linux/arm-smccc.h>
+#include <linux/dma-mapping.h>
+
+#include "qcom_scm.h"
+
+/**
+ * struct arm_smccc_args
+ * @args:	The array of values used in registers in smc instruction
+ */
+struct arm_smccc_args {
+	unsigned long args[8];
+};
+
+static DEFINE_MUTEX(qcom_scm_lock);
+
+#define QCOM_SCM_EBUSY_WAIT_MS 30
+#define QCOM_SCM_EBUSY_MAX_RETRY 20
+
+#define SCM_SMC_N_REG_ARGS	4
+#define SCM_SMC_FIRST_EXT_IDX	(SCM_SMC_N_REG_ARGS - 1)
+#define SCM_SMC_N_EXT_ARGS	(MAX_QCOM_SCM_ARGS - SCM_SMC_N_REG_ARGS + 1)
+#define SCM_SMC_FIRST_REG_IDX	2
+#define SCM_SMC_LAST_REG_IDX	(SCM_SMC_FIRST_REG_IDX + SCM_SMC_N_REG_ARGS - 1)
+
+static void __scm_smc_do_quirk(const struct arm_smccc_args *smc,
+			       struct arm_smccc_res *res)
+{
+	unsigned long a0 = smc->args[0];
+	struct arm_smccc_quirk quirk = { .id = ARM_SMCCC_QUIRK_QCOM_A6 };
+
+	quirk.state.a6 = 0;
+
+	do {
+		arm_smccc_smc_quirk(a0, smc->args[1], smc->args[2],
+				    smc->args[3], smc->args[4], smc->args[5],
+				    quirk.state.a6, smc->args[7], res, &quirk);
+
+		if (res->a0 == QCOM_SCM_INTERRUPTED)
+			a0 = res->a0;
+
+	} while (res->a0 == QCOM_SCM_INTERRUPTED);
+}
+
+static void __scm_smc_do(const struct arm_smccc_args *smc,
+			 struct arm_smccc_res *res, bool atomic)
+{
+	int retry_count = 0;
+
+	if (atomic) {
+		__scm_smc_do_quirk(smc, res);
+		return;
+	}
+
+	do {
+		mutex_lock(&qcom_scm_lock);
+
+		__scm_smc_do_quirk(smc, res);
+
+		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);
+}
+
+int scm_smc_call(struct device *dev, const struct qcom_scm_desc *desc,
+		 struct qcom_scm_res *res, bool atomic)
+{
+	int arglen = desc->arginfo & 0xf;
+	int i;
+	dma_addr_t args_phys = 0;
+	void *args_virt = NULL;
+	size_t alloc_len;
+	gfp_t flag = atomic ? GFP_ATOMIC : GFP_KERNEL;
+	u32 smccc_call_type = atomic ? ARM_SMCCC_FAST_CALL : ARM_SMCCC_STD_CALL;
+	u32 qcom_smccc_convention =
+			(qcom_scm_convention == SMC_CONVENTION_ARM_32) ?
+			ARM_SMCCC_SMC_32 : ARM_SMCCC_SMC_64;
+	struct arm_smccc_res smc_res;
+	struct arm_smccc_args smc = {0};
+
+	smc.args[0] = ARM_SMCCC_CALL_VAL(
+		smccc_call_type,
+		qcom_smccc_convention,
+		desc->owner,
+		SCM_SMC_FNID(desc->svc, desc->cmd));
+	smc.args[1] = desc->arginfo;
+	for (i = 0; i < SCM_SMC_N_REG_ARGS; i++)
+		smc.args[i + SCM_SMC_FIRST_REG_IDX] = desc->args[i];
+
+	if (unlikely(arglen > SCM_SMC_N_REG_ARGS)) {
+		alloc_len = SCM_SMC_N_EXT_ARGS * sizeof(u64);
+		args_virt = kzalloc(PAGE_ALIGN(alloc_len), flag);
+
+		if (!args_virt)
+			return -ENOMEM;
+
+		if (qcom_smccc_convention == ARM_SMCCC_SMC_32) {
+			__le32 *args = args_virt;
+
+			for (i = 0; i < SCM_SMC_N_EXT_ARGS; i++)
+				args[i] = cpu_to_le32(desc->args[i +
+						      SCM_SMC_FIRST_EXT_IDX]);
+		} else {
+			__le64 *args = args_virt;
+
+			for (i = 0; i < SCM_SMC_N_EXT_ARGS; i++)
+				args[i] = cpu_to_le64(desc->args[i +
+						      SCM_SMC_FIRST_EXT_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 -ENOMEM;
+		}
+
+		smc.args[SCM_SMC_LAST_REG_IDX] = args_phys;
+	}
+
+	__scm_smc_do(&smc, &smc_res, atomic);
+
+	if (args_virt) {
+		dma_unmap_single(dev, args_phys, alloc_len, DMA_TO_DEVICE);
+		kfree(args_virt);
+	}
+
+	if (res) {
+		res->result[0] = smc_res.a1;
+		res->result[1] = smc_res.a2;
+		res->result[2] = smc_res.a3;
+	}
+
+	return (long)smc_res.a0 ? qcom_scm_remap_error(smc_res.a0) : 0;
+}