Microchip family of RISC-V SoCs typically have one or more
clusters. These clusters can be configured to run in an Asymmetric
Multi Processing (AMP) mode where clusters are split in independent
software contexts.

Add a remoteproc platform driver to be able to load and boot firmware
to remote processors.

The driver uses SBI (RISC-V Supervisor Binary Interface) ecalls to
request software running in machine privilege mode (M-mode) to
start/stop the remote processor.

Inter-processor communication is supported through the
virtio rpmsg stack using shared memory and the Microchip IPC mailbox
driver.

Currently, the driver the following features are supported:
- Start/stop a remote software context
- Kick function implementation for RPMsg Communication
- Attach to a remote context loaded by another entity (bootloader)

Error Recovery and Power Management features are not currently supported.

Signed-off-by: Valentina Fernandez <[email protected]>
---
 drivers/remoteproc/Kconfig                   |  12 +
 drivers/remoteproc/Makefile                  |   1 +
 drivers/remoteproc/mchp_ipc_sbi_remoteproc.c | 465 +++++++++++++++++++
 3 files changed, 478 insertions(+)
 create mode 100644 drivers/remoteproc/mchp_ipc_sbi_remoteproc.c

diff --git a/drivers/remoteproc/Kconfig b/drivers/remoteproc/Kconfig
index 48a0d3a69ed0..68bd68f553ea 100644
--- a/drivers/remoteproc/Kconfig
+++ b/drivers/remoteproc/Kconfig
@@ -54,6 +54,18 @@ config INGENIC_VPU_RPROC
          This can be either built-in or a loadable module.
          If unsure say N.
 
+config MCHP_IPC_SBI_REMOTEPROC
+       tristate "Microchip IPC remoteproc support"
+       depends on MCHP_SBI_IPC_MBOX || COMPILE_TEST
+       depends on ARCH_MICROCHIP
+       help
+         Say y here to support booting and loading firmware to remote
+         processors on various Microchip family of RISC-V SoCs via the
+         remote processor framework.
+         This can be either built-in or a loadable module.
+         If compiled as module, the module will be called mchp_ipc_remoteproc.
+         If unsure say N.
+
 config MTK_SCP
        tristate "Mediatek SCP support"
        depends on ARCH_MEDIATEK || COMPILE_TEST
diff --git a/drivers/remoteproc/Makefile b/drivers/remoteproc/Makefile
index 1c7598b8475d..afb28dff5666 100644
--- a/drivers/remoteproc/Makefile
+++ b/drivers/remoteproc/Makefile
@@ -14,6 +14,7 @@ obj-$(CONFIG_REMOTEPROC_CDEV)         += remoteproc_cdev.o
 obj-$(CONFIG_IMX_REMOTEPROC)           += imx_rproc.o
 obj-$(CONFIG_IMX_DSP_REMOTEPROC)       += imx_dsp_rproc.o
 obj-$(CONFIG_INGENIC_VPU_RPROC)                += ingenic_rproc.o
+obj-$(CONFIG_MCHP_IPC_SBI_REMOTEPROC)  += mchp_ipc_sbi_remoteproc.o
 obj-$(CONFIG_MTK_SCP)                  += mtk_scp.o mtk_scp_ipi.o
 obj-$(CONFIG_OMAP_REMOTEPROC)          += omap_remoteproc.o
 obj-$(CONFIG_WKUP_M3_RPROC)            += wkup_m3_rproc.o
diff --git a/drivers/remoteproc/mchp_ipc_sbi_remoteproc.c 
b/drivers/remoteproc/mchp_ipc_sbi_remoteproc.c
new file mode 100644
index 000000000000..55d182c1eee7
--- /dev/null
+++ b/drivers/remoteproc/mchp_ipc_sbi_remoteproc.c
@@ -0,0 +1,465 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Microchip IPC Remoteproc driver
+ *
+ * Copyright (c) 2021 - 2025 Microchip Technology Inc. All rights reserved.
+ *
+ * Author: Valentina Fernandez <[email protected]>
+ *
+ * Derived from the imx_rproc implementation:
+ * Copyright (c) 2017 Pengutronix, Oleksij Rempel <[email protected]>
+ */
+
+#include <linux/err.h>
+#include <linux/kernel.h>
+#include <linux/mailbox_client.h>
+#include <linux/module.h>
+#include <linux/of_address.h>
+#include <linux/of_reserved_mem.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/remoteproc.h>
+#include <linux/workqueue.h>
+
+#include <asm/sbi.h>
+#include <asm/vendorid_list.h>
+#include <linux/mailbox/mchp-ipc.h>
+
+#include "remoteproc_internal.h"
+
+#define SBI_EXT_MICROCHIP_TECHNOLOGY   (SBI_EXT_VENDOR_START | \
+                                        MICROCHIP_VENDOR_ID)
+
+#define MIV_RPROC_MEM_MAX              2
+
+enum {
+       SBI_EXT_RPROC_STATE = 0x3,
+       SBI_EXT_RPROC_START,
+       SBI_EXT_RPROC_STOP,
+};
+
+/**
+ * enum mchp_ipc_rproc_mbox_messages - predefined mailbox messages
+ *
+ * @MCHP_IPC_RPROC_MBOX_READY: a ready message response from a remote context 
indicating
+ * that the remote context is up and running.
+ *
+ * @MCHP_IPC_RPROC_MBOX_PENDING_MSG: Not currently in use, but reserved for 
future use
+ * to inform the receiver that there is a message awaiting in its receive-side
+ * vring. At the moment, one can explicitly send the index of the triggered
+ * virtqueue as a payload.
+ *
+ * @MCHP_IPC_RPROC_MBOX_STOP: a stop request for the remote context
+ *
+ * @MCHP_IPC_RPROC_MBOX_END_MSG: Indicates end of known/defined messages.
+ * This should be the last definition.
+ *
+ */
+enum mchp_ipc_rproc_mbox_messages {
+       MCHP_IPC_RPROC_MBOX_READY = 0xFFFFFF00,
+       MCHP_IPC_RPROC_MBOX_PENDING_MSG = 0xFFFFFF01,
+       MCHP_IPC_RPROC_MBOX_STOP = 0xFFFFFF02,
+       MCHP_IPC_RPROC_MBOX_END_MSG = 0xFFFFFF03,
+};
+
+enum {
+       MCHP_IPC_RPROC_RSC_TABLE_REGION,
+       MCHP_IPC_RPROC_FW_REGION,
+       MCHP_IPC_RPROC_BUFF_REGION,
+       MCHP_IPC_RPROC_VRING0_REGION,
+       MCHP_IPC_RPROC_VRING1_REGION,
+       MCHP_IPC_RPROC_REGION_MAX,
+};
+
+struct mchp_ipc_rproc_mem_region {
+       const char *name;
+       const char *prefix;
+};
+
+struct mchp_ipc_rproc {
+       struct device *dev;
+       struct rproc *rproc;
+       struct mbox_chan *mbox_channel;
+       struct workqueue_struct *workqueue;
+       struct mbox_client mbox_client;
+       struct completion start_done;
+       struct work_struct rproc_work;
+       struct mchp_ipc_msg message;
+       void __iomem *rsc_table;
+       bool initialized;
+       u32 chan_id;
+};
+
+static struct mchp_ipc_rproc_mem_region mchp_rproc_mem_regions[] = {
+       [MCHP_IPC_RPROC_RSC_TABLE_REGION] = {
+               .name = "rsc-table",
+               .prefix = NULL,
+       },
+       [MCHP_IPC_RPROC_FW_REGION] = {
+               .name = "firmware",
+               .prefix = NULL,
+       },
+       [MCHP_IPC_RPROC_BUFF_REGION] = {
+               .name = "buffer",
+               .prefix = "vdev0",
+       },
+       [MCHP_IPC_RPROC_VRING0_REGION] = {
+               .name = "vring0",
+               .prefix = "vdev0",
+       },
+       [MCHP_IPC_RPROC_VRING1_REGION] = {
+               .name = "vring1",
+               .prefix = "vdev0",
+       },
+};
+
+static int mchp_ipc_rproc_start(struct rproc *rproc)
+{
+       struct mchp_ipc_rproc *priv = rproc->priv;
+       struct sbiret ret;
+
+       ret = sbi_ecall(SBI_EXT_MICROCHIP_TECHNOLOGY, SBI_EXT_RPROC_START,
+                       priv->chan_id, rproc->bootaddr, 0, 0, 0, 0);
+
+       if (ret.error)
+               return sbi_err_map_linux_errno(ret.error);
+
+       if (!wait_for_completion_timeout(&priv->start_done,
+                                        msecs_to_jiffies(5000))) {
+               dev_err(priv->dev, "timeout waiting for ready notification\n");
+               return -ETIMEDOUT;
+       }
+
+       return 0;
+}
+
+static int mchp_ipc_rproc_stop(struct rproc *rproc)
+{
+       struct mchp_ipc_rproc *priv = rproc->priv;
+       struct sbiret ret;
+
+       ret = sbi_ecall(SBI_EXT_MICROCHIP_TECHNOLOGY, SBI_EXT_RPROC_STOP,
+                       priv->chan_id, MCHP_IPC_RPROC_MBOX_STOP, 0, 0, 0, 0);
+
+       if (ret.error)
+               return sbi_err_map_linux_errno(ret.error);
+
+       return ret.value;
+}
+
+static int mchp_ipc_rproc_mem_alloc(struct rproc *rproc, struct 
rproc_mem_entry *mem)
+{
+       struct device *dev = rproc->dev.parent;
+       void *va;
+
+       dev_dbg(dev, "map memory: %pad+%zx\n", &mem->dma, mem->len);
+       va = ioremap_wc(mem->dma, mem->len);
+       if (IS_ERR_OR_NULL(va)) {
+               dev_err(dev, "Unable to map memory region: %p+%zx\n",
+                       &mem->dma, mem->len);
+               return -ENOMEM;
+       }
+
+       mem->va = va;
+
+       return 0;
+}
+
+static int mchp_ipc_rproc_mem_release(struct rproc *rproc,
+                                     struct rproc_mem_entry *mem)
+{
+       dev_dbg(rproc->dev.parent, "unmap memory: %pad\n", &mem->dma);
+       iounmap(mem->va);
+
+       return 0;
+}
+
+static int mchp_ipc_rproc_prepare(struct rproc *rproc)
+{
+       struct mchp_ipc_rproc *priv = rproc->priv;
+       struct device_node *np = priv->dev->of_node;
+       struct rproc_mem_entry *mem;
+       struct resource res;
+       int i, ret;
+
+       reinit_completion(&priv->start_done);
+
+       for (i = 0; i < ARRAY_SIZE(mchp_rproc_mem_regions); i++) {
+               char *mem_region_name = devm_kstrdup(priv->dev,
+                                                    
mchp_rproc_mem_regions[i].name, GFP_KERNEL);
+               int index = of_property_match_string(np, "memory-region-names", 
mem_region_name);
+
+               if (index < 0)
+                       continue;
+
+               ret = of_reserved_mem_region_to_resource_byname(np, 
mem_region_name, &res);
+               if (ret)
+                       return ret;
+
+               if (mchp_rproc_mem_regions[i].prefix) {
+                       mem_region_name = devm_kasprintf(priv->dev, GFP_KERNEL, 
"%s%s",
+                                                        
mchp_rproc_mem_regions[i].prefix,
+                                                        mem_region_name);
+               }
+
+               if (i == MCHP_IPC_RPROC_BUFF_REGION) {
+                       mem = rproc_of_resm_mem_entry_init(priv->dev, index, 
resource_size(&res),
+                                                          res.start, 
mem_region_name);
+               } else {
+                       mem = rproc_mem_entry_init(priv->dev, NULL,
+                                                  (dma_addr_t)res.start,
+                                                  resource_size(&res), 
res.start,
+                                                  mchp_ipc_rproc_mem_alloc,
+                                                  mchp_ipc_rproc_mem_release,
+                                                  mem_region_name);
+               }
+               rproc_add_carveout(rproc, mem);
+       }
+
+       return 0;
+}
+
+static int mchp_ipc_rproc_parse_fw(struct rproc *rproc, const struct firmware 
*fw)
+{
+       int ret;
+
+       ret = rproc_elf_load_rsc_table(rproc, fw);
+       if (ret)
+               dev_info(&rproc->dev, "No resource table in elf\n");
+
+       return 0;
+}
+
+static void mchp_ipc_rproc_kick(struct rproc *rproc, int vqid)
+{
+       struct mchp_ipc_rproc *priv = (struct mchp_ipc_rproc *)rproc->priv;
+       struct mchp_ipc_msg msg;
+       int ret;
+
+       msg.buf = (void *)&vqid;
+       msg.size = sizeof(vqid);
+
+       ret = mbox_send_message(priv->mbox_channel, (void *)&msg);
+       if (ret < 0)
+               dev_err(priv->dev,
+                       "failed to send mbox message, status = %d\n", ret);
+}
+
+static int mchp_ipc_rproc_attach(struct rproc *rproc)
+{
+       return 0;
+}
+
+static struct resource_table
+*mchp_ipc_rproc_get_loaded_rsc_table(struct rproc *rproc, size_t *table_sz)
+{
+       struct mchp_ipc_rproc *priv = rproc->priv;
+
+       if (!priv->rsc_table)
+               return NULL;
+
+       *table_sz = SZ_1K;
+       return (struct resource_table *)priv->rsc_table;
+}
+
+static const struct rproc_ops mchp_ipc_rproc_ops = {
+       .prepare = mchp_ipc_rproc_prepare,
+       .start = mchp_ipc_rproc_start,
+       .get_loaded_rsc_table = mchp_ipc_rproc_get_loaded_rsc_table,
+       .attach = mchp_ipc_rproc_attach,
+       .stop = mchp_ipc_rproc_stop,
+       .kick = mchp_ipc_rproc_kick,
+       .load = rproc_elf_load_segments,
+       .parse_fw = mchp_ipc_rproc_parse_fw,
+       .find_loaded_rsc_table = rproc_elf_find_loaded_rsc_table,
+       .sanity_check = rproc_elf_sanity_check,
+       .get_boot_addr = rproc_elf_get_boot_addr,
+};
+
+static void mchp_ipc_rproc_vq_work(struct work_struct *work)
+{
+       struct mchp_ipc_rproc *priv = container_of(work, struct mchp_ipc_rproc, 
rproc_work);
+       struct device *dev = priv->rproc->dev.parent;
+
+       u32 msg = priv->message.buf[0];
+
+       /*
+        * Currently, we are expected to receive the following messages
+        * from the remote cluster: a ready message or receive the index
+        * of the triggered virtqueue as a payload.
+        * We can silently ignore any other type of mailbox messages since
+        * they are not meant for us and are meant to be received by the
+        * remote cluster only.
+        */
+       switch (msg) {
+       case MCHP_IPC_RPROC_MBOX_READY:
+               complete(&priv->start_done);
+               break;
+       default:
+               if (msg >= MCHP_IPC_RPROC_MBOX_READY && msg < 
MCHP_IPC_RPROC_MBOX_END_MSG)
+                       return;
+               if (msg > priv->rproc->max_notifyid) {
+                       dev_info(dev, "dropping unknown message 0x%x", msg);
+                       return;
+               }
+               /* msg contains the index of the triggered vring */
+               if (rproc_vq_interrupt(priv->rproc, msg) == IRQ_NONE)
+                       dev_dbg(dev, "no message was found in vqid %d\n", msg);
+       }
+}
+
+static void mchp_ipc_rproc_rx_callback(struct mbox_client *mbox_client, void 
*msg)
+{
+       struct rproc *rproc = dev_get_drvdata(mbox_client->dev);
+       struct mchp_ipc_rproc *priv = rproc->priv;
+
+       priv->message = *(struct mchp_ipc_msg *)msg;
+       queue_work(priv->workqueue, &priv->rproc_work);
+}
+
+static int mchp_ipc_rproc_mbox_init(struct rproc *rproc)
+{
+       struct mchp_ipc_rproc *priv = rproc->priv;
+       struct device *dev = priv->dev;
+       struct mchp_ipc_sbi_chan *chan_priv;
+       struct mbox_client *mbox_client;
+
+       mbox_client = &priv->mbox_client;
+       mbox_client->dev = dev;
+       mbox_client->tx_block = true;
+       mbox_client->tx_tout = 100;
+       mbox_client->knows_txdone = false;
+       mbox_client->rx_callback = mchp_ipc_rproc_rx_callback;
+
+       priv->mbox_channel = mbox_request_channel(mbox_client, 0);
+       if (IS_ERR(priv->mbox_channel))
+               return dev_err_probe(mbox_client->dev,
+                                    PTR_ERR(priv->mbox_channel),
+                                    "failed to request mailbox channel\n");
+
+       chan_priv = (struct mchp_ipc_sbi_chan *)priv->mbox_channel->con_priv;
+       priv->chan_id = chan_priv->id;
+
+       return 0;
+}
+
+static int mchp_ipc_rproc_get_state(u32 chan)
+{
+       struct sbiret ret;
+
+       ret = sbi_ecall(SBI_EXT_MICROCHIP_TECHNOLOGY, SBI_EXT_RPROC_STATE,
+                       chan, 0, 0, 0, 0, 0);
+
+       if (ret.error)
+               return sbi_err_map_linux_errno(ret.error);
+
+       return ret.value;
+}
+
+static int mchp_ipc_rproc_probe(struct platform_device *pdev)
+{
+       struct device *dev = &pdev->dev;
+       struct device_node *np = dev->of_node;
+       struct mchp_ipc_rproc *priv;
+       struct rproc *rproc;
+       struct resource res;
+       int num_rmems, ret;
+
+       rproc = devm_rproc_alloc(dev, np->name, &mchp_ipc_rproc_ops,
+                                NULL, sizeof(*priv));
+       if (!rproc)
+               return -ENOMEM;
+
+       priv = rproc->priv;
+       priv->rproc = rproc;
+       priv->dev = dev;
+
+       num_rmems = of_property_count_elems_of_size(np, "memory-region",
+                                                   sizeof(phandle));
+       if (num_rmems < 1)
+               return dev_err_probe(dev, -EINVAL,
+                                    "device needs at least one memory regions 
to be defined\n");
+
+       ret = of_reserved_mem_region_to_resource_byname(np, "rsc-table", &res);
+       if (!ret) {
+               priv->rsc_table  = devm_ioremap_resource(dev, &res);
+               if (IS_ERR(priv->rsc_table)) {
+                       return dev_err_probe(dev, PTR_ERR(priv->rsc_table),
+                                            "failed to map resource table\n");
+               }
+       }
+
+       priv->workqueue = create_workqueue(dev_name(dev));
+       if (!priv->workqueue)
+               return dev_err_probe(dev, -ENOMEM, "cannot create workqueue\n");
+
+       INIT_WORK(&priv->rproc_work, mchp_ipc_rproc_vq_work);
+       init_completion(&priv->start_done);
+
+       ret = mchp_ipc_rproc_mbox_init(rproc);
+       if (ret)
+               goto err_put_wkq;
+
+       /*
+        * Check if the remote cluster has been booted by another entity
+        * (i.e. bootloader) and set rproc state accordingly
+        */
+       rproc->state = mchp_ipc_rproc_get_state(priv->chan_id);
+       if (ret < 0) {
+               dev_err_probe(dev, ret, "Couldn't get cluster boot mode\n");
+               goto err_put_mbox;
+       }
+
+       if (rproc->state != RPROC_DETACHED)
+               rproc->auto_boot = false;
+
+       /* error recovery is not supported at present */
+       rproc->recovery_disabled = true;
+
+       dev_set_drvdata(dev, rproc);
+
+       ret = devm_rproc_add(dev, rproc);
+       if (ret) {
+               dev_err_probe(dev, ret, "rproc_add failed\n");
+               goto err_put_mbox;
+       }
+
+       return 0;
+
+err_put_mbox:
+       mbox_free_channel(priv->mbox_channel);
+err_put_wkq:
+       destroy_workqueue(priv->workqueue);
+
+       return ret;
+}
+
+static void mchp_ipc_rproc_remove(struct platform_device *pdev)
+{
+       struct rproc *rproc = platform_get_drvdata(pdev);
+       struct mchp_ipc_rproc *priv = rproc->priv;
+
+       mbox_free_channel(priv->mbox_channel);
+       destroy_workqueue(priv->workqueue);
+}
+
+static const struct of_device_id mchp_ipc_rproc_of_match[] __maybe_unused = {
+       { .compatible = "microchip,ipc-sbi-remoteproc", },
+       {}
+};
+MODULE_DEVICE_TABLE(of, mchp_ipc_rproc_of_match);
+
+static struct platform_driver mchp_ipc_rproc_driver = {
+       .probe = mchp_ipc_rproc_probe,
+       .remove = mchp_ipc_rproc_remove,
+       .driver = {
+               .name = "microchip-ipc-rproc",
+               .of_match_table = of_match_ptr(mchp_ipc_rproc_of_match),
+       },
+};
+
+module_platform_driver(mchp_ipc_rproc_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Valentina Fernandez <[email protected]>");
+MODULE_DESCRIPTION("Microchip IPC Remote Processor control driver");
-- 
2.34.1


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