[PATCH v3 3/3] remoteproc: xilinx: add mailbox channels for rpmsg

[Tanmay Shah]

This patch makes each r5 core mailbox client and uses
tx and rx channels to send and receive data to/from
remote processor respectively. This is needed for rpmsg
communication to remote processor.

Signed-off-by: Tanmay Shah <tanmay.shah@xxxxxxx>
---

Changes in v3:
  - fix multi-line comment format
  - do not mixup mailbox information with memory-regions
  - fix redundant dev_warn for split mode
  - setting up mailboxes should return an error code
  - redesign driver to move mailbox setup during driver probe
  - add .kick function only if mailbox setup is success

v2: https://lore.kernel.org/all/20230126213154.1707300-1-tanmay.shah@xxxxxxx/

 drivers/remoteproc/xlnx_r5_remoteproc.c | 228 +++++++++++++++++++++++-
 1 file changed, 226 insertions(+), 2 deletions(-)

diff --git a/drivers/remoteproc/xlnx_r5_remoteproc.c b/drivers/remoteproc/xlnx_r5_remoteproc.c
index 81af2dea56c2..f7131fe8fe7e 100644
--- a/drivers/remoteproc/xlnx_r5_remoteproc.c
+++ b/drivers/remoteproc/xlnx_r5_remoteproc.c
@@ -8,16 +8,23 @@
 #include <linux/dma-mapping.h>
 #include <linux/firmware/xlnx-zynqmp.h>
 #include <linux/kernel.h>
+#include <linux/mailbox_client.h>
+#include <linux/mailbox/zynqmp-ipi-message.h>
 #include <linux/module.h>
 #include <linux/of_address.h>
 #include <linux/of_platform.h>
 #include <linux/of_reserved_mem.h>
 #include <linux/platform_device.h>
 #include <linux/remoteproc.h>
-#include <linux/slab.h>
 
 #include "remoteproc_internal.h"
 
+/* IPI buffer MAX length */
+#define IPI_BUF_LEN_MAX	32U
+
+/* RX mailbox client buffer max length */
+#define MBOX_CLIENT_BUF_MAX	(IPI_BUF_LEN_MAX + \
+				 sizeof(struct zynqmp_ipi_message))
 /*
  * settings for RPU cluster mode which
  * reflects possible values of xlnx,cluster-mode dt-property
@@ -43,6 +50,27 @@ struct mem_bank_data {
 	char *bank_name;
 };
 
+/**
+ * struct mbox_info
+ *
+ * @rx_mc_buf: to copy data from mailbox rx channel
+ * @tx_mc_buf: to copy data to mailbox tx channel
+ * @r5_core: this mailbox's corresponding r5_core pointer
+ * @mbox_work: schedule work after receiving data from mailbox
+ * @mbox_cl: mailbox client
+ * @tx_chan: mailbox tx channel
+ * @rx_chan: mailbox rx channel
+ */
+struct mbox_info {
+	unsigned char rx_mc_buf[MBOX_CLIENT_BUF_MAX];
+	unsigned char tx_mc_buf[MBOX_CLIENT_BUF_MAX];
+	struct zynqmp_r5_core *r5_core;
+	struct work_struct mbox_work;
+	struct mbox_client mbox_cl;
+	struct mbox_chan *tx_chan;
+	struct mbox_chan *rx_chan;
+};
+
 /*
  * Hardcoded TCM bank values. This will be removed once TCM bindings are
  * accepted for system-dt specifications and upstreamed in linux kernel
@@ -63,6 +91,7 @@ static const struct mem_bank_data zynqmp_tcm_banks[] = {
  * @tcm_banks: array of each TCM bank data
  * @rproc: rproc handle
  * @pm_domain_id: RPU CPU power domain id
+ * @ipi: pointer to mailbox information
  */
 struct zynqmp_r5_core {
 	struct device *dev;
@@ -71,6 +100,7 @@ struct zynqmp_r5_core {
 	struct mem_bank_data **tcm_banks;
 	struct rproc *rproc;
 	u32 pm_domain_id;
+	struct mbox_info *ipi;
 };
 
 /**
@@ -88,6 +118,178 @@ struct zynqmp_r5_cluster {
 	struct zynqmp_r5_core **r5_cores;
 };
 
+/**
+ * event_notified_idr_cb() - callback for vq_interrupt per notifyid
+ * @id: rproc->notify id
+ * @ptr: pointer to idr private data
+ * @data: data passed to idr_for_each callback
+ *
+ * Pass notification to remoteproc virtio
+ *
+ * Return: 0. having return is to satisfy the idr_for_each() function
+ *          pointer input argument requirement.
+ **/
+static int event_notified_idr_cb(int id, void *ptr, void *data)
+{
+	struct rproc *rproc = data;
+
+	if (rproc_vq_interrupt(rproc, id) == IRQ_NONE)
+		dev_dbg(&rproc->dev, "data not found for vqid=%d\n", id);
+
+	return 0;
+}
+
+/**
+ * handle_event_notified() - remoteproc notification work function
+ * @work: pointer to the work structure
+ *
+ * It checks each registered remoteproc notify IDs.
+ */
+static void handle_event_notified(struct work_struct *work)
+{
+	struct mbox_info *ipi;
+	struct rproc *rproc;
+
+	ipi = container_of(work, struct mbox_info, mbox_work);
+	rproc = ipi->r5_core->rproc;
+
+	/*
+	 * We only use IPI for interrupt. The RPU firmware side may or may
+	 * not write the notifyid when it trigger IPI.
+	 * And thus, we scan through all the registered notifyids and
+	 * find which one is valid to get the message.
+	 * Even if message from firmware is NULL, we attempt to get vqid
+	 */
+	idr_for_each(&rproc->notifyids, event_notified_idr_cb, rproc);
+}
+
+/**
+ * zynqmp_r5_mb_rx_cb() - receive channel mailbox callback
+ * @cl: mailbox client
+ * @msg: message pointer
+ *
+ * Receive data from ipi buffer, ack interrupt and then
+ * it will schedule the R5 notification work.
+ */
+static void zynqmp_r5_mb_rx_cb(struct mbox_client *cl, void *msg)
+{
+	struct zynqmp_ipi_message *ipi_msg, *buf_msg;
+	struct mbox_info *ipi;
+	size_t len;
+
+	ipi = container_of(cl, struct mbox_info, mbox_cl);
+
+	/* copy data from ipi buffer to r5_core */
+	ipi_msg = (struct zynqmp_ipi_message *)msg;
+	buf_msg = (struct zynqmp_ipi_message *)ipi->rx_mc_buf;
+	len = ipi_msg->len;
+	if (len > IPI_BUF_LEN_MAX) {
+		dev_warn(cl->dev, "msg size exceeded than %d\n",
+			 IPI_BUF_LEN_MAX);
+		len = IPI_BUF_LEN_MAX;
+	}
+	buf_msg->len = len;
+	memcpy(buf_msg->data, ipi_msg->data, len);
+
+	/* received and processed interrupt ack */
+	if (mbox_send_message(ipi->rx_chan, NULL) < 0)
+		dev_err(cl->dev, "ack failed to mbox rx_chan\n");
+
+	schedule_work(&ipi->mbox_work);
+}
+
+/**
+ * zynqmp_r5_setup_mbox() - Setup mailboxes related properties
+ *			    this is used for each individual R5 core
+ *
+ * @cdev: child node device
+ *
+ * Function to setup mailboxes related properties
+ * return : NULL if failed else pointer to mbox_info
+ */
+static struct mbox_info *zynqmp_r5_setup_mbox(struct device *cdev)
+{
+	struct mbox_client *mbox_cl;
+	struct mbox_info *ipi;
+
+	ipi = kzalloc(sizeof(*ipi), GFP_KERNEL);
+	if (!ipi)
+		return NULL;
+
+	mbox_cl = &ipi->mbox_cl;
+	mbox_cl->rx_callback = zynqmp_r5_mb_rx_cb;
+	mbox_cl->tx_block = false;
+	mbox_cl->knows_txdone = false;
+	mbox_cl->tx_done = NULL;
+	mbox_cl->dev = cdev;
+
+	/* Request TX and RX channels */
+	ipi->tx_chan = mbox_request_channel_byname(mbox_cl, "tx");
+	if (IS_ERR(ipi->tx_chan)) {
+		ipi->tx_chan = NULL;
+		kfree(ipi);
+		dev_warn(cdev, "mbox tx channel request failed\n");
+		return NULL;
+	}
+
+	ipi->rx_chan = mbox_request_channel_byname(mbox_cl, "rx");
+	if (IS_ERR(ipi->rx_chan)) {
+		mbox_free_channel(ipi->tx_chan);
+		ipi->rx_chan = NULL;
+		ipi->tx_chan = NULL;
+		kfree(ipi);
+		dev_warn(cdev, "mbox rx channel request failed\n");
+		return NULL;
+	}
+
+	INIT_WORK(&ipi->mbox_work, handle_event_notified);
+
+	return ipi;
+}
+
+static void zynqmp_r5_free_mbox(struct mbox_info *ipi)
+{
+	if (!ipi)
+		return;
+
+	if (ipi->tx_chan) {
+		mbox_free_channel(ipi->tx_chan);
+		ipi->tx_chan = NULL;
+	}
+
+	if (ipi->rx_chan) {
+		mbox_free_channel(ipi->rx_chan);
+		ipi->rx_chan = NULL;
+	}
+
+	kfree(ipi);
+}
+
+/*
+ * zynqmp_r5_core_kick() - kick a firmware if mbox is provided
+ * @rproc: r5 core's corresponding rproc structure
+ * @vqid: virtqueue ID
+ */
+static void zynqmp_r5_rproc_kick(struct rproc *rproc, int vqid)
+{
+	struct zynqmp_r5_core *r5_core = rproc->priv;
+	struct device *dev = r5_core->dev;
+	struct zynqmp_ipi_message *mb_msg;
+	struct mbox_info *ipi;
+	int ret;
+
+	ipi = r5_core->ipi;
+	if (!ipi)
+		return;
+
+	mb_msg = (struct zynqmp_ipi_message *)ipi->tx_mc_buf;
+	memcpy(mb_msg->data, &vqid, sizeof(vqid));
+	mb_msg->len = sizeof(vqid);
+	ret = mbox_send_message(ipi->tx_chan, mb_msg);
+	if (ret < 0)
+		dev_warn(dev, "failed to send message\n");
+}
+
 /*
  * zynqmp_r5_set_mode()
  *
@@ -617,7 +819,7 @@ static int zynqmp_r5_rproc_unprepare(struct rproc *rproc)
 	return 0;
 }
 
-static const struct rproc_ops zynqmp_r5_rproc_ops = {
+static struct rproc_ops zynqmp_r5_rproc_ops = {
 	.prepare	= zynqmp_r5_rproc_prepare,
 	.unprepare	= zynqmp_r5_rproc_unprepare,
 	.start		= zynqmp_r5_rproc_start,
@@ -642,6 +844,7 @@ static struct zynqmp_r5_core *zynqmp_r5_add_rproc_core(struct device *cdev)
 {
 	struct zynqmp_r5_core *r5_core;
 	struct rproc *r5_rproc;
+	struct mbox_info *ipi;
 	int ret;
 
 	/* Set up DMA mask */
@@ -649,12 +852,23 @@ static struct zynqmp_r5_core *zynqmp_r5_add_rproc_core(struct device *cdev)
 	if (ret)
 		return ERR_PTR(ret);
 
+	/*
+	 * If mailbox nodes are disabled using "status" property then setting up
+	 * mailbox channels will be failed. In that case we don't really need
+	 * kick() operation. Include .kick() only if mbox channels are acquired
+	 * successfully.
+	 */
+	ipi = zynqmp_r5_setup_mbox(cdev);
+	if (ipi)
+		zynqmp_r5_rproc_ops.kick = zynqmp_r5_rproc_kick;
+
 	/* Allocate remoteproc instance */
 	r5_rproc = rproc_alloc(cdev, dev_name(cdev),
 			       &zynqmp_r5_rproc_ops,
 			       NULL, sizeof(struct zynqmp_r5_core));
 	if (!r5_rproc) {
 		dev_err(cdev, "failed to allocate memory for rproc instance\n");
+		zynqmp_r5_free_mbox(ipi);
 		return ERR_PTR(-ENOMEM);
 	}
 
@@ -665,6 +879,7 @@ static struct zynqmp_r5_core *zynqmp_r5_add_rproc_core(struct device *cdev)
 	if (!r5_core->np) {
 		dev_err(cdev, "can't get device node for r5 core\n");
 		ret = -EINVAL;
+		zynqmp_r5_free_mbox(ipi);
 		goto free_rproc;
 	}
 
@@ -672,10 +887,17 @@ static struct zynqmp_r5_core *zynqmp_r5_add_rproc_core(struct device *cdev)
 	ret = rproc_add(r5_rproc);
 	if (ret) {
 		dev_err(cdev, "failed to add r5 remoteproc\n");
+		zynqmp_r5_free_mbox(ipi);
 		goto free_rproc;
 	}
 
+	if (ipi) {
+		r5_core->ipi = ipi;
+		ipi->r5_core = r5_core;
+	}
+
 	r5_core->rproc = r5_rproc;
+
 	return r5_core;
 
 free_rproc:
@@ -918,6 +1140,7 @@ static int zynqmp_r5_cluster_init(struct zynqmp_r5_cluster *cluster)
 	while (i >= 0) {
 		put_device(child_devs[i]);
 		if (r5_cores[i]) {
+			zynqmp_r5_free_mbox(r5_cores[i]->ipi);
 			of_reserved_mem_device_release(r5_cores[i]->dev);
 			rproc_del(r5_cores[i]->rproc);
 			rproc_free(r5_cores[i]->rproc);
@@ -942,6 +1165,7 @@ static void zynqmp_r5_cluster_exit(void *data)
 
 	for (i = 0; i < cluster->core_count; i++) {
 		r5_core = cluster->r5_cores[i];
+		zynqmp_r5_free_mbox(r5_core->ipi);
 		of_reserved_mem_device_release(r5_core->dev);
 		put_device(r5_core->dev);
 		rproc_del(r5_core->rproc);
-- 
2.25.1