[PATCH V3 07/11] i3c: mipi-i3c-hci: Allow for Multi-Bus Instances

Adrian Hunter
2025-12-16T16:57:06Z

Add support for MIPI I3C Host Controllers with the Multi-Bus Instance
capability. These controllers can host multiple I3C buses (up to 15)
within a single hardware function (e.g., PCIe B/D/F), providing one
indepedent HCI register set and corresponding I3C bus controller logic
per bus.

A separate platform device will represent each instance, but it is
necessary to allow for shared resources.

Multi-bus instances share the same MMIO address space, but the ranges are
not guaranteed to be contiguous. To avoid overlapping mappings, pass
base_regs from the parent mapping to child devices.

Allow the IRQ to be shared among instances.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
---

Changes in V3:

Enhance commit message

Changes in V2:

None

drivers/i3c/master/mipi-i3c-hci/core.c | 21 +++++++++++++++++----
include/linux/platform_data/mipi-i3c-hci.h | 15 +++++++++++++++
2 files changed, 32 insertions(+), 4 deletions(-)
create mode 100644 include/linux/platform_data/mipi-i3c-hci.h

diff --git a/drivers/i3c/master/mipi-i3c-hci/core.c b/drivers/i3c/master/mipi-i3c-hci/core.c
index 3d6544a64188..6da5daf18166 100644
--- a/drivers/i3c/master/mipi-i3c-hci/core.c
+++ b/drivers/i3c/master/mipi-i3c-hci/core.c
@@ -14,6 +14,7 @@
#include <linux/interrupt.h>
#include <linux/iopoll.h>
#include <linux/module.h>
+#include <linux/platform_data/mipi-i3c-hci.h>
#include <linux/platform_device.h>

#include "hci.h"
@@ -737,15 +738,27 @@ static int i3c_hci_init(struct i3c_hci *hci)

static int i3c_hci_probe(struct platform_device *pdev)
{
+ const struct mipi_i3c_hci_platform_data *pdata = pdev->dev.platform_data;
struct i3c_hci *hci;
int irq, ret;

hci = devm_kzalloc(&pdev->dev, sizeof(*hci), GFP_KERNEL);
if (!hci)
return -ENOMEM;
- hci->base_regs = devm_platform_ioremap_resource(pdev, 0);
- if (IS_ERR(hci->base_regs))
- return PTR_ERR(hci->base_regs);
+
+ /*
+ * Multi-bus instances share the same MMIO address range, but not
+ * necessarily in separate contiguous sub-ranges. To avoid overlapping
+ * mappings, provide base_regs from the parent mapping.
+ */
+ if (pdata)
+ hci->base_regs = pdata->base_regs;
+
+ if (!hci->base_regs) {
+ hci->base_regs = devm_platform_ioremap_resource(pdev, 0);
+ if (IS_ERR(hci->base_regs))
+ return PTR_ERR(hci->base_regs);
+ }

platform_set_drvdata(pdev, hci);
/* temporary for dev_printk's, to be replaced in i3c_master_register */
@@ -759,7 +772,7 @@ static int i3c_hci_probe(struct platform_device *pdev)

irq = platform_get_irq(pdev, 0);
ret = devm_request_irq(&pdev->dev, irq, i3c_hci_irq_handler,
- 0, NULL, hci);
+ IRQF_SHARED, NULL, hci);
if (ret)
return ret;

diff --git a/include/linux/platform_data/mipi-i3c-hci.h b/include/linux/platform_data/mipi-i3c-hci.h
new file mode 100644
index 000000000000..ab7395f455f9
--- /dev/null
+++ b/include/linux/platform_data/mipi-i3c-hci.h
@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef INCLUDE_PLATFORM_DATA_MIPI_I3C_HCI_H
+#define INCLUDE_PLATFORM_DATA_MIPI_I3C_HCI_H
+
+#include <linux/compiler_types.h>
+
+/**
+ * struct mipi_i3c_hci_platform_data - Platform-dependent data for mipi_i3c_hci
+ * @base_regs: Register set base address (to support multi-bus instances)
+ */
+struct mipi_i3c_hci_platform_data {
+ void __iomem *base_regs;
+};
+
+#endif