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, 242 insertions, 0 deletions

diff --git a/drivers/firmware/qcom_scm-legacy.c b/drivers/firmware/qcom_scm-legacy.c
new file mode 100644
index 000000000000..8532e7c78ef7
--- /dev/null
+++ b/drivers/firmware/qcom_scm-legacy.c
@@ -0,0 +1,242 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright (c) 2010,2015,2019 The Linux Foundation. All rights reserved.
+ * Copyright (C) 2015 Linaro Ltd.
+ */
+
+#include <linux/slab.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/errno.h>
+#include <linux/err.h>
+#include <linux/qcom_scm.h>
+#include <linux/arm-smccc.h>
+#include <linux/dma-mapping.h>
+
+#include "qcom_scm.h"
+
+static DEFINE_MUTEX(qcom_scm_lock);
+
+
+/**
+ * struct arm_smccc_args
+ * @args:	The array of values used in registers in smc instruction
+ */
+struct arm_smccc_args {
+	unsigned long args[8];
+};
+
+
+/**
+ * struct scm_legacy_command - one SCM command buffer
+ * @len: total available memory for command and response
+ * @buf_offset: start of command buffer
+ * @resp_hdr_offset: start of response buffer
+ * @id: command to be executed
+ * @buf: buffer returned from scm_legacy_get_command_buffer()
+ *
+ * An SCM command is laid out in memory as follows:
+ *
+ *	------------------- <--- struct scm_legacy_command
+ *	| command header  |
+ *	------------------- <--- scm_legacy_get_command_buffer()
+ *	| command buffer  |
+ *	------------------- <--- struct scm_legacy_response and
+ *	| response header |      scm_legacy_command_to_response()
+ *	------------------- <--- scm_legacy_get_response_buffer()
+ *	| response buffer |
+ *	-------------------
+ *
+ * There can be arbitrary padding between the headers and buffers so
+ * you should always use the appropriate scm_legacy_get_*_buffer() routines
+ * to access the buffers in a safe manner.
+ */
+struct scm_legacy_command {
+	__le32 len;
+	__le32 buf_offset;
+	__le32 resp_hdr_offset;
+	__le32 id;
+	__le32 buf[0];
+};
+
+/**
+ * struct scm_legacy_response - one SCM response buffer
+ * @len: total available memory for response
+ * @buf_offset: start of response data relative to start of scm_legacy_response
+ * @is_complete: indicates if the command has finished processing
+ */
+struct scm_legacy_response {
+	__le32 len;
+	__le32 buf_offset;
+	__le32 is_complete;
+};
+
+/**
+ * scm_legacy_command_to_response() - Get a pointer to a scm_legacy_response
+ * @cmd: command
+ *
+ * Returns a pointer to a response for a command.
+ */
+static inline struct scm_legacy_response *scm_legacy_command_to_response(
+		const struct scm_legacy_command *cmd)
+{
+	return (void *)cmd + le32_to_cpu(cmd->resp_hdr_offset);
+}
+
+/**
+ * scm_legacy_get_command_buffer() - Get a pointer to a command buffer
+ * @cmd: command
+ *
+ * Returns a pointer to the command buffer of a command.
+ */
+static inline void *scm_legacy_get_command_buffer(
+		const struct scm_legacy_command *cmd)
+{
+	return (void *)cmd->buf;
+}
+
+/**
+ * scm_legacy_get_response_buffer() - Get a pointer to a response buffer
+ * @rsp: response
+ *
+ * Returns a pointer to a response buffer of a response.
+ */
+static inline void *scm_legacy_get_response_buffer(
+		const struct scm_legacy_response *rsp)
+{
+	return (void *)rsp + le32_to_cpu(rsp->buf_offset);
+}
+
+static void __scm_legacy_do(const struct arm_smccc_args *smc,
+			    struct arm_smccc_res *res)
+{
+	do {
+		arm_smccc_smc(smc->args[0], smc->args[1], smc->args[2],
+			      smc->args[3], smc->args[4], smc->args[5],
+			      smc->args[6], smc->args[7], res);
+	} while (res->a0 == QCOM_SCM_INTERRUPTED);
+}
+
+/**
+ * qcom_scm_call() - Sends a command to the SCM and waits for the command to
+ * finish processing.
+ *
+ * A note on cache maintenance:
+ * Note that any buffers that are expected to be accessed by the secure world
+ * must be flushed before invoking qcom_scm_call and invalidated in the cache
+ * immediately after qcom_scm_call returns. Cache maintenance on the command
+ * and response buffers is taken care of by qcom_scm_call; however, callers are
+ * responsible for any other cached buffers passed over to the secure world.
+ */
+int scm_legacy_call(struct device *dev, const struct qcom_scm_desc *desc,
+		    struct qcom_scm_res *res)
+{
+	u8 arglen = desc->arginfo & 0xf;
+	int ret = 0, context_id;
+	unsigned int i;
+	struct scm_legacy_command *cmd;
+	struct scm_legacy_response *rsp;
+	struct arm_smccc_args smc = {0};
+	struct arm_smccc_res smc_res;
+	const size_t cmd_len = arglen * sizeof(__le32);
+	const size_t resp_len = MAX_QCOM_SCM_RETS * sizeof(__le32);
+	size_t alloc_len = sizeof(*cmd) + cmd_len + sizeof(*rsp) + resp_len;
+	dma_addr_t cmd_phys;
+	__le32 *arg_buf;
+	const __le32 *res_buf;
+
+	cmd = kzalloc(PAGE_ALIGN(alloc_len), GFP_KERNEL);
+	if (!cmd)
+		return -ENOMEM;
+
+	cmd->len = cpu_to_le32(alloc_len);
+	cmd->buf_offset = cpu_to_le32(sizeof(*cmd));
+	cmd->resp_hdr_offset = cpu_to_le32(sizeof(*cmd) + cmd_len);
+	cmd->id = cpu_to_le32(SCM_LEGACY_FNID(desc->svc, desc->cmd));
+
+	arg_buf = scm_legacy_get_command_buffer(cmd);
+	for (i = 0; i < arglen; i++)
+		arg_buf[i] = cpu_to_le32(desc->args[i]);
+
+	rsp = scm_legacy_command_to_response(cmd);
+
+	cmd_phys = dma_map_single(dev, cmd, alloc_len, DMA_TO_DEVICE);
+	if (dma_mapping_error(dev, cmd_phys)) {
+		kfree(cmd);
+		return -ENOMEM;
+	}
+
+	smc.args[0] = 1;
+	smc.args[1] = (unsigned long)&context_id;
+	smc.args[2] = cmd_phys;
+
+	mutex_lock(&qcom_scm_lock);
+	__scm_legacy_do(&smc, &smc_res);
+	if (smc_res.a0)
+		ret = qcom_scm_remap_error(smc_res.a0);
+	mutex_unlock(&qcom_scm_lock);
+	if (ret)
+		goto out;
+
+	do {
+		dma_sync_single_for_cpu(dev, cmd_phys + sizeof(*cmd) + cmd_len,
+					sizeof(*rsp), DMA_FROM_DEVICE);
+	} while (!rsp->is_complete);
+
+	dma_sync_single_for_cpu(dev, cmd_phys + sizeof(*cmd) + cmd_len +
+				le32_to_cpu(rsp->buf_offset),
+				resp_len, DMA_FROM_DEVICE);
+
+	if (res) {
+		res_buf = scm_legacy_get_response_buffer(rsp);
+		for (i = 0; i < MAX_QCOM_SCM_RETS; i++)
+			res->result[i] = le32_to_cpu(res_buf[i]);
+	}
+out:
+	dma_unmap_single(dev, cmd_phys, alloc_len, DMA_TO_DEVICE);
+	kfree(cmd);
+	return ret;
+}
+
+#define SCM_LEGACY_ATOMIC_N_REG_ARGS	5
+#define SCM_LEGACY_ATOMIC_FIRST_REG_IDX	2
+#define SCM_LEGACY_CLASS_REGISTER		(0x2 << 8)
+#define SCM_LEGACY_MASK_IRQS		BIT(5)
+#define SCM_LEGACY_ATOMIC_ID(svc, cmd, n) \
+				((SCM_LEGACY_FNID(svc, cmd) << 12) | \
+				SCM_LEGACY_CLASS_REGISTER | \
+				SCM_LEGACY_MASK_IRQS | \
+				(n & 0xf))
+
+/**
+ * qcom_scm_call_atomic() - Send an atomic SCM command with up to 5 arguments
+ * and 3 return values
+ * @desc: SCM call descriptor containing arguments
+ * @res:  SCM call return values
+ *
+ * This shall only be used with commands that are guaranteed to be
+ * uninterruptable, atomic and SMP safe.
+ */
+int scm_legacy_call_atomic(struct device *unused,
+			   const struct qcom_scm_desc *desc,
+			   struct qcom_scm_res *res)
+{
+	int context_id;
+	struct arm_smccc_res smc_res;
+	size_t arglen = desc->arginfo & 0xf;
+
+	BUG_ON(arglen > SCM_LEGACY_ATOMIC_N_REG_ARGS);
+
+	arm_smccc_smc(SCM_LEGACY_ATOMIC_ID(desc->svc, desc->cmd, arglen),
+		      (unsigned long)&context_id,
+		      desc->args[0], desc->args[1], desc->args[2],
+		      desc->args[3], desc->args[4], 0, &smc_res);
+
+	if (res) {
+		res->result[0] = smc_res.a1;
+		res->result[1] = smc_res.a2;
+		res->result[2] = smc_res.a3;
+	}
+
+	return smc_res.a0;
+}