[PATCH v3 13/23] irqchip: Add driver for the RPMI system MSI service group

Anup Patel
2025-05-11T13:41:55Z

The RPMI specification defines a system MSI service group which
allows application processors to receive MSIs upon system events
such as graceful shutdown/reboot request, CPU hotplug event, memory
hotplug event, etc.

Add an irqchip driver for the RISC-V RPMI system MSI service group
to directly receive system MSIs in Linux kernel.

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
---
drivers/irqchip/Kconfig | 7 +
drivers/irqchip/Makefile | 1 +
drivers/irqchip/irq-riscv-rpmi-sysmsi.c | 280 +++++++++++++++++++++
include/linux/mailbox/riscv-rpmi-message.h | 13 +
4 files changed, 301 insertions(+)
create mode 100644 drivers/irqchip/irq-riscv-rpmi-sysmsi.c

diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
index 08bb3b031f23..83700fc2ddc9 100644
--- a/drivers/irqchip/Kconfig
+++ b/drivers/irqchip/Kconfig
@@ -612,6 +612,13 @@ config RISCV_IMSIC
select GENERIC_MSI_IRQ
select IRQ_MSI_LIB

+config RISCV_RPMI_SYSMSI
+ bool
+ depends on MAILBOX
+ select IRQ_DOMAIN_HIERARCHY
+ select GENERIC_MSI_IRQ
+ default RISCV
+
config SIFIVE_PLIC
bool
depends on RISCV
diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
index 365bcea9a61f..515280da499c 100644
--- a/drivers/irqchip/Makefile
+++ b/drivers/irqchip/Makefile
@@ -102,6 +102,7 @@ obj-$(CONFIG_RISCV_INTC) += irq-riscv-intc.o
obj-$(CONFIG_RISCV_APLIC) += irq-riscv-aplic-main.o irq-riscv-aplic-direct.o
obj-$(CONFIG_RISCV_APLIC_MSI) += irq-riscv-aplic-msi.o
obj-$(CONFIG_RISCV_IMSIC) += irq-riscv-imsic-state.o irq-riscv-imsic-early.o irq-riscv-imsic-platform.o
+obj-$(CONFIG_RISCV_RPMI_SYSMSI) += irq-riscv-rpmi-sysmsi.o
obj-$(CONFIG_SIFIVE_PLIC) += irq-sifive-plic.o
obj-$(CONFIG_STARFIVE_JH8100_INTC) += irq-starfive-jh8100-intc.o
obj-$(CONFIG_THEAD_C900_ACLINT_SSWI) += irq-thead-c900-aclint-sswi.o
diff --git a/drivers/irqchip/irq-riscv-rpmi-sysmsi.c b/drivers/irqchip/irq-riscv-rpmi-sysmsi.c
new file mode 100644
index 000000000000..9f14a92290c4
--- /dev/null
+++ b/drivers/irqchip/irq-riscv-rpmi-sysmsi.c
@@ -0,0 +1,280 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2025 Ventana Micro Systems Inc.
+ */
+
+#include <linux/bitfield.h>
+#include <linux/bitops.h>
+#include <linux/cpu.h>
+#include <linux/interrupt.h>
+#include <linux/irqchip.h>
+#include <linux/mailbox_client.h>
+#include <linux/mailbox/riscv-rpmi-message.h>
+#include <linux/module.h>
+#include <linux/msi.h>
+#include <linux/of_irq.h>
+#include <linux/platform_device.h>
+#include <linux/printk.h>
+#include <linux/smp.h>
+
+struct rpmi_sysmsi_get_attrs_rx {
+ s32 status;
+ u32 sys_num_msi;
+ u32 flag0;
+ u32 flag1;
+};
+
+#define RPMI_SYSMSI_MSI_ATTRIBUTES_FLAG0_PREF_PRIV BIT(0)
+
+struct rpmi_sysmsi_set_msi_state_tx {
+ u32 sys_msi_index;
+ u32 sys_msi_state;
+};
+
+struct rpmi_sysmsi_set_msi_state_rx {
+ s32 status;
+};
+
+#define RPMI_SYSMSI_MSI_STATE_ENABLE BIT(0)
+#define RPMI_SYSMSI_MSI_STATE_PENDING BIT(1)
+
+struct rpmi_sysmsi_set_msi_target_tx {
+ u32 sys_msi_index;
+ u32 sys_msi_address_low;
+ u32 sys_msi_address_high;
+ u32 sys_msi_data;
+};
+
+struct rpmi_sysmsi_set_msi_target_rx {
+ s32 status;
+};
+
+struct rpmi_sysmsi_priv {
+ struct device *dev;
+ struct mbox_client client;
+ struct mbox_chan *chan;
+ u32 nr_irqs;
+ u32 gsi_base;
+};
+
+static int rpmi_sysmsi_get_num_msi(struct rpmi_sysmsi_priv *priv)
+{
+ struct rpmi_sysmsi_get_attrs_rx rx;
+ struct rpmi_mbox_message msg;
+ int ret;
+
+ rpmi_mbox_init_send_with_response(&msg, RPMI_SYSMSI_SRV_GET_ATTRIBUTES,
+ NULL, 0, &rx, sizeof(rx));
+ ret = rpmi_mbox_send_message(priv->chan, &msg);
+ if (ret)
+ return ret;
+ if (rx.status)
+ return rpmi_to_linux_error(rx.status);
+
+ return rx.sys_num_msi;
+}
+
+static int rpmi_sysmsi_set_msi_state(struct rpmi_sysmsi_priv *priv,
+ u32 sys_msi_index, u32 sys_msi_state)
+{
+ struct rpmi_sysmsi_set_msi_state_tx tx;
+ struct rpmi_sysmsi_set_msi_state_rx rx;
+ struct rpmi_mbox_message msg;
+ int ret;
+
+ tx.sys_msi_index = sys_msi_index;
+ tx.sys_msi_state = sys_msi_state;
+ rpmi_mbox_init_send_with_response(&msg, RPMI_SYSMSI_SRV_SET_MSI_STATE,
+ &tx, sizeof(tx), &rx, sizeof(rx));
+ ret = rpmi_mbox_send_message(priv->chan, &msg);
+ if (ret)
+ return ret;
+ if (rx.status)
+ return rpmi_to_linux_error(rx.status);
+
+ return 0;
+}
+
+static int rpmi_sysmsi_set_msi_target(struct rpmi_sysmsi_priv *priv,
+ u32 sys_msi_index, struct msi_msg *m)
+{
+ struct rpmi_sysmsi_set_msi_target_tx tx;
+ struct rpmi_sysmsi_set_msi_target_rx rx;
+ struct rpmi_mbox_message msg;
+ int ret;
+
+ tx.sys_msi_index = sys_msi_index;
+ tx.sys_msi_address_low = m->address_lo;
+ tx.sys_msi_address_high = m->address_hi;
+ tx.sys_msi_data = m->data;
+ rpmi_mbox_init_send_with_response(&msg, RPMI_SYSMSI_SRV_SET_MSI_TARGET,
+ &tx, sizeof(tx), &rx, sizeof(rx));
+ ret = rpmi_mbox_send_message(priv->chan, &msg);
+ if (ret)
+ return ret;
+ if (rx.status)
+ return rpmi_to_linux_error(rx.status);
+
+ return 0;
+}
+
+static void rpmi_sysmsi_irq_mask(struct irq_data *d)
+{
+ struct rpmi_sysmsi_priv *priv = irq_data_get_irq_chip_data(d);
+ int ret;
+
+ ret = rpmi_sysmsi_set_msi_state(priv, d->hwirq, 0);
+ if (ret) {
+ dev_warn(priv->dev, "Failed to mask hwirq %d (error %d)\n",
+ (u32)d->hwirq, ret);
+ }
+ irq_chip_mask_parent(d);
+}
+
+static void rpmi_sysmsi_irq_unmask(struct irq_data *d)
+{
+ struct rpmi_sysmsi_priv *priv = irq_data_get_irq_chip_data(d);
+ int ret;
+
+ irq_chip_unmask_parent(d);
+ ret = rpmi_sysmsi_set_msi_state(priv, d->hwirq, RPMI_SYSMSI_MSI_STATE_ENABLE);
+ if (ret) {
+ dev_warn(priv->dev, "Failed to unmask hwirq %d (error %d)\n",
+ (u32)d->hwirq, ret);
+ }
+}
+
+static void rpmi_sysmsi_write_msg(struct irq_data *d, struct msi_msg *msg)
+{
+ struct rpmi_sysmsi_priv *priv = irq_data_get_irq_chip_data(d);
+ int ret;
+
+ /* For zeroed MSI, do nothing as of now */
+ if (!msg->address_hi && !msg->address_lo && !msg->data)
+ return;
+
+ ret = rpmi_sysmsi_set_msi_target(priv, d->hwirq, msg);
+ if (ret) {
+ dev_warn(priv->dev, "Failed to set target for hwirq %d (error %d)\n",
+ (u32)d->hwirq, ret);
+ }
+}
+
+static void rpmi_sysmsi_set_desc(msi_alloc_info_t *arg, struct msi_desc *desc)
+{
+ arg->desc = desc;
+ arg->hwirq = (u32)desc->data.icookie.value;
+}
+
+static int rpmi_sysmsi_translate(struct irq_domain *d, struct irq_fwspec *fwspec,
+ unsigned long *hwirq, unsigned int *type)
+{
+ struct msi_domain_info *info = d->host_data;
+ struct rpmi_sysmsi_priv *priv = info->data;
+
+ if (WARN_ON(fwspec->param_count < 1))
+ return -EINVAL;
+
+ /* For DT, gsi_base is always zero. */
+ *hwirq = fwspec->param[0] - priv->gsi_base;
+ *type = IRQ_TYPE_NONE;
+ return 0;
+}
+
+static const struct msi_domain_template rpmi_sysmsi_template = {
+ .chip = {
+ .name = "RPMI-SYSMSI",
+ .irq_mask = rpmi_sysmsi_irq_mask,
+ .irq_unmask = rpmi_sysmsi_irq_unmask,
+#ifdef CONFIG_SMP
+ .irq_set_affinity = irq_chip_set_affinity_parent,
+#endif
+ .irq_write_msi_msg = rpmi_sysmsi_write_msg,
+ .flags = IRQCHIP_SET_TYPE_MASKED |
+ IRQCHIP_SKIP_SET_WAKE |
+ IRQCHIP_MASK_ON_SUSPEND,
+ },
+
+ .ops = {
+ .set_desc = rpmi_sysmsi_set_desc,
+ .msi_translate = rpmi_sysmsi_translate,
+ },
+
+ .info = {
+ .bus_token = DOMAIN_BUS_WIRED_TO_MSI,
+ .flags = MSI_FLAG_USE_DEV_FWNODE,
+ .handler = handle_simple_irq,
+ .handler_name = "simple",
+ },
+};
+
+static int rpmi_sysmsi_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct rpmi_sysmsi_priv *priv;
+ int rc;
+
+ priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+ if (!priv)
+ return -ENOMEM;
+ priv->dev = dev;
+ platform_set_drvdata(pdev, priv);
+
+ /* Setup mailbox client */
+ priv->client.dev = priv->dev;
+ priv->client.rx_callback = NULL;
+ priv->client.tx_block = false;
+ priv->client.knows_txdone = true;
+ priv->client.tx_tout = 0;
+
+ /* Request mailbox channel */
+ priv->chan = mbox_request_channel(&priv->client, 0);
+ if (IS_ERR(priv->chan))
+ return PTR_ERR(priv->chan);
+
+ /* Get number of system MSIs */
+ rc = rpmi_sysmsi_get_num_msi(priv);
+ if (rc < 1) {
+ mbox_free_channel(priv->chan);
+ return dev_err_probe(dev, -ENODEV, "No system MSIs found\n");
+ }
+ priv->nr_irqs = rc;
+
+ /* Set the device MSI domain if not available */
+ if (!dev_get_msi_domain(dev)) {
+ /*
+ * The device MSI domain for OF devices is only set at the
+ * time of populating/creating OF device. If the device MSI
+ * domain is discovered later after the OF device is created
+ * then we need to set it explicitly before using any platform
+ * MSI functions.
+ */
+ if (is_of_node(dev_fwnode(dev)))
+ of_msi_configure(dev, to_of_node(dev_fwnode(dev)));
+
+ if (!dev_get_msi_domain(dev))
+ return -EPROBE_DEFER;
+ }
+
+ if (!msi_create_device_irq_domain(dev, MSI_DEFAULT_DOMAIN,
+ &rpmi_sysmsi_template,
+ priv->nr_irqs, priv, priv))
+ return dev_err_probe(dev, -ENOMEM, "failed to create MSI irq domain\n");
+
+ dev_info(dev, "%d system MSIs registered\n", priv->nr_irqs);
+ return 0;
+}
+
+static const struct of_device_id rpmi_sysmsi_match[] = {
+ { .compatible = "riscv,rpmi-system-msi" },
+ {}
+};
+
+static struct platform_driver rpmi_sysmsi_driver = {
+ .driver = {
+ .name = "rpmi-sysmsi",
+ .of_match_table = rpmi_sysmsi_match,
+ },
+ .probe = rpmi_sysmsi_probe,
+};
+builtin_platform_driver(rpmi_sysmsi_driver);
diff --git a/include/linux/mailbox/riscv-rpmi-message.h b/include/linux/mailbox/riscv-rpmi-message.h
index dfffe4804ec7..7cd6507c153b 100644
--- a/include/linux/mailbox/riscv-rpmi-message.h
+++ b/include/linux/mailbox/riscv-rpmi-message.h
@@ -90,6 +90,7 @@ static inline int rpmi_to_linux_error(int rpmi_error)
}

/** RPMI service group IDs */
+#define RPMI_SRVGRP_SYSTEM_MSI 0x00002
#define RPMI_SRVGRP_CLOCK 0x00008

/** RPMI clock service IDs */
@@ -105,6 +106,18 @@ enum rpmi_clock_service_id {
RPMI_CLK_SRV_ID_MAX_COUNT,
};

+/** RPMI system MSI service IDs */
+enum rpmi_sysmsi_service_id {
+ RPMI_SYSMSI_SRV_ENABLE_NOTIFICATION = 0x01,
+ RPMI_SYSMSI_SRV_GET_ATTRIBUTES = 0x2,
+ RPMI_SYSMSI_SRV_GET_MSI_ATTRIBUTES = 0x3,
+ RPMI_SYSMSI_SRV_SET_MSI_STATE = 0x4,
+ RPMI_SYSMSI_SRV_GET_MSI_STATE = 0x5,
+ RPMI_SYSMSI_SRV_SET_MSI_TARGET = 0x6,
+ RPMI_SYSMSI_SRV_GET_MSI_TARGET = 0x7,
+ RPMI_SYSMSI_SRV_ID_MAX_COUNT,
+};
+
/** RPMI linux mailbox attribute IDs */
enum rpmi_mbox_attribute_id {
RPMI_MBOX_ATTR_SPEC_VERSION = 0,
--
2.43.0