firmware: arm_scmi: Support 'reg-io-width' property for shared memory

Some shared memory areas might only support a certain access width,
such as 32-bit, which memcpy_{from,to}_io() does not adhere to at least
on ARM64 by making both 8-bit and 64-bit accesses to such memory.

Update the shmem layer to support reading from and writing to such
shared memory area using the specified I/O width in the Device Tree. The
various transport layers making use of the shmem.c code are updated
accordingly to pass the I/O accessors that they store.

Signed-off-by: Florian Fainelli <[e-mail]>
Message-Id: <[e-mail]>
Signed-off-by: Sudeep Holla <[e-mail]>

drivers/firmware/arm_scmi/common.h

···
 	MSG_MBOX_SPURIOUS = -5,
 };
 
+/* Used for compactness and signature validation of the function pointers being
+ * passed.
+ */
+typedef void (*shmem_copy_toio_t)(void __iomem *to, const void *from,
+				  size_t count);
+typedef void (*shmem_copy_fromio_t)(void *to, const void __iomem *from,
+				    size_t count);
+
+/**
+ * struct scmi_shmem_io_ops  - I/O operations to read from/write to
+ * Shared Memory
+ *
+ * @toio: Copy data to the shared memory area
+ * @fromio: Copy data from the shared memory area
+ */
+struct scmi_shmem_io_ops {
+	shmem_copy_fromio_t fromio;
+	shmem_copy_toio_t toio;
+};
+
 /* shmem related declarations */
 struct scmi_shared_mem;
 
···
 struct scmi_shared_mem_operations {
 	void (*tx_prepare)(struct scmi_shared_mem __iomem *shmem,
 			   struct scmi_xfer *xfer,
-			   struct scmi_chan_info *cinfo);
+			   struct scmi_chan_info *cinfo,
+			   shmem_copy_toio_t toio);
 	u32 (*read_header)(struct scmi_shared_mem __iomem *shmem);
 
 	void (*fetch_response)(struct scmi_shared_mem __iomem *shmem,
-			       struct scmi_xfer *xfer);
+			       struct scmi_xfer *xfer,
+			       shmem_copy_fromio_t fromio);
 	void (*fetch_notification)(struct scmi_shared_mem __iomem *shmem,
-				   size_t max_len, struct scmi_xfer *xfer);
+				   size_t max_len, struct scmi_xfer *xfer,
+				   shmem_copy_fromio_t fromio);
 	void (*clear_channel)(struct scmi_shared_mem __iomem *shmem);
 	bool (*poll_done)(struct scmi_shared_mem __iomem *shmem,
 			  struct scmi_xfer *xfer);
···
 	bool (*channel_intr_enabled)(struct scmi_shared_mem __iomem *shmem);
 	void __iomem *(*setup_iomap)(struct scmi_chan_info *cinfo,
 				     struct device *dev,
-				     bool tx, struct resource *res);
+				     bool tx, struct resource *res,
+				     struct scmi_shmem_io_ops **ops);
 };
 
 const struct scmi_shared_mem_operations *scmi_shared_mem_operations_get(void);

drivers/firmware/arm_scmi/shmem.c

···
 	u8 msg_payload[];
 };
 
+static inline void shmem_memcpy_fromio32(void *to,
+					 const void __iomem *from,
+					 size_t count)
+{
+	WARN_ON(!IS_ALIGNED((unsigned long)from, 4) ||
+		!IS_ALIGNED((unsigned long)to, 4) ||
+		count % 4);
+
+	__ioread32_copy(to, from, count / 4);
+}
+
+static inline void shmem_memcpy_toio32(void __iomem *to,
+				       const void *from,
+				       size_t count)
+{
+	WARN_ON(!IS_ALIGNED((unsigned long)to, 4) ||
+		!IS_ALIGNED((unsigned long)from, 4) ||
+		count % 4);
+
+	__iowrite32_copy(to, from, count / 4);
+}
+
+static struct scmi_shmem_io_ops shmem_io_ops32 = {
+	.fromio	= shmem_memcpy_fromio32,
+	.toio	= shmem_memcpy_toio32,
+};
+
+/* Wrappers are needed for proper memcpy_{from,to}_io expansion by the
+ * pre-processor.
+ */
+static inline void shmem_memcpy_fromio(void *to,
+				       const void __iomem *from,
+				       size_t count)
+{
+	memcpy_fromio(to, from, count);
+}
+
+static inline void shmem_memcpy_toio(void __iomem *to,
+				     const void *from,
+				     size_t count)
+{
+	memcpy_toio(to, from, count);
+}
+
+static struct scmi_shmem_io_ops shmem_io_ops_default = {
+	.fromio = shmem_memcpy_fromio,
+	.toio	= shmem_memcpy_toio,
+};
+
 static void shmem_tx_prepare(struct scmi_shared_mem __iomem *shmem,
 			     struct scmi_xfer *xfer,
-			     struct scmi_chan_info *cinfo)
+			     struct scmi_chan_info *cinfo,
+			     shmem_copy_toio_t copy_toio)
 {
 	ktime_t stop;
 
···
 	iowrite32(sizeof(shmem->msg_header) + xfer->tx.len, &shmem->length);
 	iowrite32(pack_scmi_header(&xfer->hdr), &shmem->msg_header);
 	if (xfer->tx.buf)
-		memcpy_toio(shmem->msg_payload, xfer->tx.buf, xfer->tx.len);
+		copy_toio(shmem->msg_payload, xfer->tx.buf, xfer->tx.len);
 }
 
 static u32 shmem_read_header(struct scmi_shared_mem __iomem *shmem)
···
 }
 
 static void shmem_fetch_response(struct scmi_shared_mem __iomem *shmem,
-				 struct scmi_xfer *xfer)
+				 struct scmi_xfer *xfer,
+				 shmem_copy_fromio_t copy_fromio)
 {
 	size_t len = ioread32(&shmem->length);
 
···
 	xfer->rx.len = min_t(size_t, xfer->rx.len, len > 8 ? len - 8 : 0);
 
 	/* Take a copy to the rx buffer.. */
-	memcpy_fromio(xfer->rx.buf, shmem->msg_payload + 4, xfer->rx.len);
+	copy_fromio(xfer->rx.buf, shmem->msg_payload + 4, xfer->rx.len);
 }
 
 static void shmem_fetch_notification(struct scmi_shared_mem __iomem *shmem,
-				     size_t max_len, struct scmi_xfer *xfer)
+				     size_t max_len, struct scmi_xfer *xfer,
+				     shmem_copy_fromio_t copy_fromio)
 {
 	size_t len = ioread32(&shmem->length);
 
···
 	xfer->rx.len = min_t(size_t, max_len, len > 4 ? len - 4 : 0);
 
 	/* Take a copy to the rx buffer.. */
-	memcpy_fromio(xfer->rx.buf, shmem->msg_payload, xfer->rx.len);
+	copy_fromio(xfer->rx.buf, shmem->msg_payload, xfer->rx.len);
 }
 
 static void shmem_clear_channel(struct scmi_shared_mem __iomem *shmem)
···
 
 static void __iomem *shmem_setup_iomap(struct scmi_chan_info *cinfo,
 				       struct device *dev, bool tx,
-				       struct resource *res)
+				       struct resource *res,
+				       struct scmi_shmem_io_ops **ops)
 {
 	struct device_node *shmem __free(device_node);
 	const char *desc = tx ? "Tx" : "Rx";
···
 	struct resource lres = {};
 	resource_size_t size;
 	void __iomem *addr;
+	u32 reg_io_width;
 
 	shmem = of_parse_phandle(cdev->of_node, "shmem", idx);
 	if (!shmem)
···
 	if (!addr) {
 		dev_err(dev, "failed to ioremap SCMI %s shared memory\n", desc);
 		return IOMEM_ERR_PTR(-EADDRNOTAVAIL);
+	}
+
+	of_property_read_u32(shmem, "reg-io-width", &reg_io_width);
+	switch (reg_io_width) {
+	case 4:
+		*ops = &shmem_io_ops32;
+		break;
+	default:
+		*ops = &shmem_io_ops_default;
+		break;
 	}
 
 	return addr;

drivers/firmware/arm_scmi/transports/mailbox.c

···
  * @cinfo: SCMI channel info
  * @shmem: Transmit/Receive shared memory area
  * @chan_lock: Lock that prevents multiple xfers from being queued
+ * @io_ops: Transport specific I/O operations
  */
 struct scmi_mailbox {
 	struct mbox_client cl;
···
 	struct scmi_chan_info *cinfo;
 	struct scmi_shared_mem __iomem *shmem;
 	struct mutex chan_lock;
+	struct scmi_shmem_io_ops *io_ops;
 };
 
 #define client_to_scmi_mailbox(c) container_of(c, struct scmi_mailbox, cl)
···
 {
 	struct scmi_mailbox *smbox = client_to_scmi_mailbox(cl);
 
-	core->shmem->tx_prepare(smbox->shmem, m, smbox->cinfo);
+	core->shmem->tx_prepare(smbox->shmem, m, smbox->cinfo,
+				smbox->io_ops->toio);
 }
 
 static void rx_callback(struct mbox_client *cl, void *m)
···
 	if (!smbox)
 		return -ENOMEM;
 
-	smbox->shmem = core->shmem->setup_iomap(cinfo, dev, tx, NULL);
+	smbox->shmem = core->shmem->setup_iomap(cinfo, dev, tx, NULL,
+						&smbox->io_ops);
 	if (IS_ERR(smbox->shmem))
 		return PTR_ERR(smbox->shmem);
 
···
 {
 	struct scmi_mailbox *smbox = cinfo->transport_info;
 
-	core->shmem->fetch_response(smbox->shmem, xfer);
+	core->shmem->fetch_response(smbox->shmem, xfer, smbox->io_ops->fromio);
 }
 
 static void mailbox_fetch_notification(struct scmi_chan_info *cinfo,
···
 {
 	struct scmi_mailbox *smbox = cinfo->transport_info;
 
-	core->shmem->fetch_notification(smbox->shmem, max_len, xfer);
+	core->shmem->fetch_notification(smbox->shmem, max_len, xfer,
+					smbox->io_ops->fromio);
 }
 
 static void mailbox_clear_channel(struct scmi_chan_info *cinfo)

drivers/firmware/arm_scmi/transports/optee.c

···
  * @req.shmem: Virtual base address of the shared memory
  * @req.msg: Shared memory protocol handle for SCMI request and
  *   synchronous response
+ * @io_ops: Transport specific I/O operations
  * @tee_shm: TEE shared memory handle @req or NULL if using IOMEM shmem
  * @link: Reference in agent's channel list
  */
···
 		struct scmi_shared_mem __iomem *shmem;
 		struct scmi_msg_payld *msg;
 	} req;
+	struct scmi_shmem_io_ops *io_ops;
 	struct tee_shm *tee_shm;
 	struct list_head link;
 };
···
 static int setup_static_shmem(struct device *dev, struct scmi_chan_info *cinfo,
 			      struct scmi_optee_channel *channel)
 {
-	channel->req.shmem = core->shmem->setup_iomap(cinfo, dev, true, NULL);
+	channel->req.shmem = core->shmem->setup_iomap(cinfo, dev, true, NULL,
+						      &channel->io_ops);
 	if (IS_ERR(channel->req.shmem))
 		return PTR_ERR(channel->req.shmem);
 
···
 		ret = invoke_process_msg_channel(channel,
 						 core->msg->command_size(xfer));
 	} else {
-		core->shmem->tx_prepare(channel->req.shmem, xfer, cinfo);
+		core->shmem->tx_prepare(channel->req.shmem, xfer, cinfo,
+					channel->io_ops->toio);
 		ret = invoke_process_smt_channel(channel);
 	}
 
···
 		core->msg->fetch_response(channel->req.msg,
 					  channel->rx_len, xfer);
 	else
-		core->shmem->fetch_response(channel->req.shmem, xfer);
+		core->shmem->fetch_response(channel->req.shmem, xfer,
+					    channel->io_ops->fromio);
 }
 
 static void scmi_optee_mark_txdone(struct scmi_chan_info *cinfo, int ret,

drivers/firmware/arm_scmi/transports/smc.c

···
  * @irq: An optional IRQ for completion
  * @cinfo: SCMI channel info
  * @shmem: Transmit/Receive shared memory area
+ * @io_ops: Transport specific I/O operations
  * @shmem_lock: Lock to protect access to Tx/Rx shared memory area.
  *		Used when NOT operating in atomic mode.
  * @inflight: Atomic flag to protect access to Tx/Rx shared memory area.
···
 	int irq;
 	struct scmi_chan_info *cinfo;
 	struct scmi_shared_mem __iomem *shmem;
+	struct scmi_shmem_io_ops *io_ops;
 	/* Protect access to shmem area */
 	struct mutex shmem_lock;
 #define INFLIGHT_NONE	MSG_TOKEN_MAX
···
 	if (!scmi_info)
 		return -ENOMEM;
 
-	scmi_info->shmem = core->shmem->setup_iomap(cinfo, dev, tx, &res);
+	scmi_info->shmem = core->shmem->setup_iomap(cinfo, dev, tx, &res,
+						    &scmi_info->io_ops);
 	if (IS_ERR(scmi_info->shmem))
 		return PTR_ERR(scmi_info->shmem);
 
···
 	 */
 	smc_channel_lock_acquire(scmi_info, xfer);
 
-	core->shmem->tx_prepare(scmi_info->shmem, xfer, cinfo);
+	core->shmem->tx_prepare(scmi_info->shmem, xfer, cinfo,
+				scmi_info->io_ops->toio);
 
 	if (scmi_info->cap_id != ULONG_MAX)
 		arm_smccc_1_1_invoke(scmi_info->func_id, scmi_info->cap_id, 0,
···
 {
 	struct scmi_smc *scmi_info = cinfo->transport_info;
 
-	core->shmem->fetch_response(scmi_info->shmem, xfer);
+	core->shmem->fetch_response(scmi_info->shmem, xfer,
+				    scmi_info->io_ops->fromio);
 }
 
 static void smc_mark_txdone(struct scmi_chan_info *cinfo, int ret,