[RFC PATCH 1/2] irqchip: cdx-bus: add cdx-MSI domain with gic-its domain as parent

Nipun Gupta
2022-08-03T12:27:38Z

Devices on cdx bus are dynamically detected and registered using
platform_device_register API. As these devices are not linked to
of node they need a separate MSI domain for handling device ID
to be provided to the GIC ITS domain.

Signed-off-by: Nipun Gupta <nipun.gupta@amd.com>
Signed-off-by: Nikhil Agarwal <nikhil.agarwal@amd.com>
---
CONFIG_CDX_BUS and device tree bindings for xlnx,cdx-controller-1.0
would be added as part of CDX bus patches

drivers/irqchip/Makefile | 1 +
drivers/irqchip/irq-gic-v3-its-cdx-msi.c | 113 +++++++++++++++++++++++
include/linux/cdx/cdx.h | 15 +++
3 files changed, 129 insertions(+)
create mode 100644 drivers/irqchip/irq-gic-v3-its-cdx-msi.c
create mode 100644 include/linux/cdx/cdx.h

diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
index 5b67450a9538..623adb8a1f20 100644
--- a/drivers/irqchip/Makefile
+++ b/drivers/irqchip/Makefile
@@ -115,3 +115,4 @@ obj-$(CONFIG_WPCM450_AIC) += irq-wpcm450-aic.o
obj-$(CONFIG_IRQ_IDT3243X) += irq-idt3243x.o
obj-$(CONFIG_APPLE_AIC) += irq-apple-aic.o
obj-$(CONFIG_MCHP_EIC) += irq-mchp-eic.o
+obj-$(CONFIG_CDX_BUS) += irq-gic-v3-its-cdx-msi.o
diff --git a/drivers/irqchip/irq-gic-v3-its-cdx-msi.c b/drivers/irqchip/irq-gic-v3-its-cdx-msi.c
new file mode 100644
index 000000000000..eb17b74efdc5
--- /dev/null
+++ b/drivers/irqchip/irq-gic-v3-its-cdx-msi.c
@@ -0,0 +1,113 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * AMD CDX bus driver MSI support
+ *
+ * Copyright(C) 2022 Xilinx Inc.
+ */
+
+#include <linux/irq.h>
+#include <linux/msi.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_device.h>
+#include <linux/of_irq.h>
+#include <linux/cdx/cdx.h>
+
+static struct irq_chip its_msi_irq_chip = {
+ .name = "ITS-fMSI",
+ .irq_mask = irq_chip_mask_parent,
+ .irq_unmask = irq_chip_unmask_parent,
+ .irq_eoi = irq_chip_eoi_parent,
+ .irq_set_affinity = msi_domain_set_affinity
+};
+
+static int its_cdx_msi_prepare(struct irq_domain *msi_domain,
+ struct device *dev,
+ int nvec, msi_alloc_info_t *info)
+{
+ struct msi_domain_info *msi_info;
+ struct cdx_device_data *dev_data;
+ u32 dev_id;
+
+ dev_data = dev->platform_data;
+ dev_id = dev_data->dev_id;
+
+ /* Set the device Id to be passed to the GIC-ITS */
+ info->scratchpad[0].ul = dev_id;
+
+ msi_info = msi_get_domain_info(msi_domain->parent);
+
+ /* Allocate at least 32 MSIs, and always as a power of 2 */
+ nvec = max_t(int, 32, roundup_pow_of_two(nvec));
+ return msi_info->ops->msi_prepare(msi_domain->parent, dev, nvec, info);
+}
+
+static struct msi_domain_ops its_cdx_msi_ops __ro_after_init = {
+ .msi_prepare = its_cdx_msi_prepare,
+};
+
+static struct msi_domain_info its_cdx_msi_domain_info = {
+ .flags = (MSI_FLAG_USE_DEF_DOM_OPS | MSI_FLAG_USE_DEF_CHIP_OPS),
+ .ops = &its_cdx_msi_ops,
+ .chip = &its_msi_irq_chip,
+};
+
+static const struct of_device_id cdx_device_id[] = {
+ {.compatible = "xlnx,cdx-controller-1.0", },
+ {},
+};
+
+struct irq_domain *get_parent(struct fwnode_handle *handle)
+{
+ return irq_find_matching_fwnode(handle, DOMAIN_BUS_NEXUS);
+}
+
+static void __init its_cdx_msi_init_one(struct device_node *np,
+ const char *name)
+{
+ struct irq_domain *parent;
+ struct irq_domain *cdx_msi_domain;
+ struct fwnode_handle *fwnode_handle;
+ struct device_node *parent_node;
+
+ parent_node = of_parse_phandle(np, "msi-parent", 0);
+
+ parent = get_parent(of_node_to_fwnode(parent_node));
+ if (!parent || !msi_get_domain_info(parent)) {
+ pr_err("%s: unable to locate ITS domain\n", name);
+ return;
+ }
+
+ fwnode_handle = of_node_to_fwnode(np);
+ cdx_msi_domain = platform_msi_create_irq_domain(fwnode_handle,
+ &its_cdx_msi_domain_info,
+ parent);
+ if (!cdx_msi_domain) {
+ pr_err("%s: unable to create cdx bus domain\n", name);
+ return;
+ }
+
+ pr_info("cdx bus MSI: %s domain created\n", name);
+}
+
+static void __init its_cdx_of_msi_init(void)
+{
+ struct device_node *np;
+
+ for (np = of_find_matching_node(NULL, cdx_device_id); np;
+ np = of_find_matching_node(np, cdx_device_id)) {
+ if (!of_device_is_available(np))
+ continue;
+
+ its_cdx_msi_init_one(np, np->full_name);
+ }
+}
+
+static int __init its_cdx_msi_init(void)
+{
+ its_cdx_of_msi_init();
+
+ return 0;
+}
+
+early_initcall(its_cdx_msi_init);
diff --git a/include/linux/cdx/cdx.h b/include/linux/cdx/cdx.h
new file mode 100644
index 000000000000..244ad721771d
--- /dev/null
+++ b/include/linux/cdx/cdx.h
@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * AMD CDX bus public interface
+ *
+ * Copyright(C) 2022 Xilinx Inc.
+ */
+
+#ifndef _CDX_H_
+#define _CDX_H_
+
+struct cdx_device_data {
+ int dev_id;
+};
+
+#endif /* _CDX_H_ */
--
2.25.1