[PATCH v6 0/5] PCI: EP: Add RC-to-EP doorbell with platform MSI controller

[PATCH v6 0/5] PCI: EP: Add RC-to-EP doorbell with platform MSI controller

[Frank Li]

┌────────────┐   ┌───────────────────────────────────┐   ┌────────────────┐
│            │   │                                   │   │                │
│            │   │ PCI Endpoint                      │   │ PCI Host       │
│            │   │                                   │   │                │
│            │◄──┤ 1.platform_msi_domain_alloc_irqs()│   │                │
│            │   │                                   │   │                │
│ MSI        ├──►│ 2.write_msi_msg()                 ├──►├─BAR<n>         │
│ Controller │   │   update doorbell register address│   │                │
│            │   │   for BAR                         │   │                │
│            │   │                                   │   │ 3. Write BAR<n>│
│            │◄──┼───────────────────────────────────┼───┤                │
│            │   │                                   │   │                │
│            ├──►│ 4.Irq Handle                      │   │                │
│            │   │                                   │   │                │
│            │   │                                   │   │                │
└────────────┘   └───────────────────────────────────┘   └────────────────┘

This patches based on old https://lore.kernel.org/imx/20221124055036.1630573-1-Frank.Li@nxp.com/

Original patch only target to vntb driver. But actually it is common
method.

This patches add new API to pci-epf-core, so any EP driver can use it.

Previous v2 discussion here.
https://lore.kernel.org/imx/20230911220920.1817033-1-Frank.Li@nxp.com/

Changes in v6:
- change doorbell_addr to doorbell_offset
- use round_down()
- add Niklas's test by tag
- rebase to pci/endpoint
- Link to v5: https://lore.kernel.org/r/20241108-ep-msi-v5-0-a14951c0d007@nxp.com

Changes in v5:
- Move request_irq to epf test function driver for more flexiable user case
- Add fixed size bar handler
- Some minor improvememtn to see each patches's changelog.
- Link to v4: https://lore.kernel.org/r/20241031-ep-msi-v4-0-717da2d99b28@nxp.com

Changes in v4:
- Remove patch genirq/msi: Add cleanup guard define for msi_lock_descs()/msi_unlock_descs()
- Use new method to avoid compatible problem.
  Add new command DOORBELL_ENABLE and DOORBELL_DISABLE.
  pcitest -B send DOORBELL_ENABLE first, EP test function driver try to
remap one of BAR_N (except test register bar) to ITS MSI MMIO space. Old
driver don't support new command, so failure return, not side effect.
  After test, DOORBELL_DISABLE command send out to recover original map, so
pcitest bar test can pass as normal.
- Other detail change see each patches's change log
- Link to v3: https://lore.kernel.org/r/20241015-ep-msi-v3-0-cedc89a16c1a@nxp.com

Change from v2 to v3
- Fixed manivannan's comments
- Move common part to pci-ep-msi.c and pci-ep-msi.h
- rebase to 6.12-rc1
- use RevID to distingiush old version

mkdir /sys/kernel/config/pci_ep/functions/pci_epf_test/func1
echo 16 > /sys/kernel/config/pci_ep/functions/pci_epf_test/func1/msi_interrupts
echo 0x080c > /sys/kernel/config/pci_ep/functions/pci_epf_test/func1/deviceid
echo 0x1957 > /sys/kernel/config/pci_ep/functions/pci_epf_test/func1/vendorid
echo 1 > /sys/kernel/config/pci_ep/functions/pci_epf_test/func1/revid
^^^^^^ to enable platform msi support.
ln -s /sys/kernel/config/pci_ep/functions/pci_epf_test/func1 /sys/kernel/config/pci_ep/controllers/4c380000.pcie-ep

- use new device ID, which identify support doorbell to avoid broken
compatility.

    Enable doorbell support only for PCI_DEVICE_ID_IMX8_DB, while other devices
    keep the same behavior as before.

           EP side             RC with old driver      RC with new driver
    PCI_DEVICE_ID_IMX8_DB          no probe              doorbell enabled
    Other device ID             doorbell disabled*       doorbell disabled*

    * Behavior remains unchanged.

Change from v1 to v2
- Add missed patch for endpont/pci-epf-test.c
- Move alloc and free to epc driver from epf.
- Provide general help function for EPC driver to alloc platform msi irq.
- Fixed manivannan's comments.

To: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
To: Krzysztof Wilczyński <kw@linux.com>
To: Kishon Vijay Abraham I <kishon@kernel.org>
To: Bjorn Helgaas <bhelgaas@google.com>
To: Arnd Bergmann <arnd@arndb.de>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-kernel@vger.kernel.org
Cc: linux-pci@vger.kernel.org
Cc: imx@lists.linux.dev
Cc: Niklas Cassel <cassel@kernel.org>
Cc: cassel@kernel.org
Cc: dlemoal@kernel.org
Cc: maz@kernel.org
Cc: tglx@linutronix.de
Cc: jdmason@kudzu.us

Signed-off-by: Frank Li <Frank.Li@nxp.com>
---
Frank Li (5):
      PCI: endpoint: Add pci_epc_get_fn() API for customizable filtering
      PCI: endpoint: Add RC-to-EP doorbell support using platform MSI controller
      PCI: endpoint: pci-epf-test: Add doorbell test support
      misc: pci_endpoint_test: Add doorbell test case
      tools: PCI: Add 'B' option for test doorbell

 drivers/misc/pci_endpoint_test.c              |  71 ++++++++++++++
 drivers/pci/endpoint/Makefile                 |   2 +-
 drivers/pci/endpoint/functions/pci-epf-test.c | 129 ++++++++++++++++++++++++++
 drivers/pci/endpoint/pci-ep-msi.c             |  99 ++++++++++++++++++++
 drivers/pci/endpoint/pci-epc-core.c           |  23 ++++-
 include/linux/pci-ep-msi.h                    |  15 +++
 include/linux/pci-epc.h                       |   2 +
 include/linux/pci-epf.h                       |  16 ++++
 include/uapi/linux/pcitest.h                  |   1 +
 tools/pci/pcitest.c                           |  16 +++-
 10 files changed, 370 insertions(+), 4 deletions(-)
---
base-commit: f5373677e13177cfc7875f44a864f9a1db751df9
change-id: 20241010-ep-msi-8b4cab33b1be

Best regards,
---
Frank Li <Frank.Li@nxp.com>

[PATCH v6 1/5] PCI: endpoint: Add pci_epc_get_fn() API for customizable filtering

[Frank Li]

Introduce the pci_epc_get_fn() API, allowing a custom filter callback
function to be passed. Reimplement pci_epc_get() using pci_epc_get_fn()
with a match name callback. Prepare the codebase for adding RC-to-EP
doorbell support.

Add DEFINE_FREE(pci_epc_put) to implement scope based auto cleanup.

Tested-by: Niklas Cassel <cassel@kernel.org>
Signed-off-by: Frank Li <Frank.Li@nxp.com>
---
change from v3 to v6
- none
---
 drivers/pci/endpoint/pci-epc-core.c | 23 +++++++++++++++++++++--
 include/linux/pci-epc.h             |  2 ++
 2 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/endpoint/pci-epc-core.c b/drivers/pci/endpoint/pci-epc-core.c
index bed7c7d1fe3c3..f5538c007678e 100644
--- a/drivers/pci/endpoint/pci-epc-core.c
+++ b/drivers/pci/endpoint/pci-epc-core.c
@@ -48,6 +48,11 @@ void pci_epc_put(struct pci_epc *epc)
 }
 EXPORT_SYMBOL_GPL(pci_epc_put);
 
+static bool pci_epc_match_name(struct device *dev, void *name)
+{
+	return strcmp(dev_name(dev), name) == 0;
+}
+
 /**
  * pci_epc_get() - get the PCI endpoint controller
  * @epc_name: device name of the endpoint controller
@@ -56,6 +61,20 @@ EXPORT_SYMBOL_GPL(pci_epc_put);
  * endpoint controller
  */
 struct pci_epc *pci_epc_get(const char *epc_name)
+{
+	return pci_epc_get_fn(pci_epc_match_name, (void *)epc_name);
+}
+EXPORT_SYMBOL_GPL(pci_epc_get);
+
+/**
+ * pci_epc_get_fn() - get the PCI endpoint controller
+ * @fn: callback match filter function, return true when matched
+ * @param: parameter for callback function fn
+ *
+ * Invoke to get struct pci_epc * corresponding to the device name of the
+ * endpoint controller
+ */
+struct pci_epc *pci_epc_get_fn(bool (*fn)(struct device *dev, void *param), void *param)
 {
 	int ret = -EINVAL;
 	struct pci_epc *epc;
@@ -64,7 +83,7 @@ struct pci_epc *pci_epc_get(const char *epc_name)
 
 	class_dev_iter_init(&iter, &pci_epc_class, NULL, NULL);
 	while ((dev = class_dev_iter_next(&iter))) {
-		if (strcmp(epc_name, dev_name(dev)))
+		if (!fn(dev, param))
 			continue;
 
 		epc = to_pci_epc(dev);
@@ -82,7 +101,7 @@ struct pci_epc *pci_epc_get(const char *epc_name)
 	class_dev_iter_exit(&iter);
 	return ERR_PTR(ret);
 }
-EXPORT_SYMBOL_GPL(pci_epc_get);
+EXPORT_SYMBOL_GPL(pci_epc_get_fn);
 
 /**
  * pci_epc_get_first_free_bar() - helper to get first unreserved BAR
diff --git a/include/linux/pci-epc.h b/include/linux/pci-epc.h
index de8cc3658220b..d3d3b8c914614 100644
--- a/include/linux/pci-epc.h
+++ b/include/linux/pci-epc.h
@@ -300,7 +300,9 @@ pci_epc_get_first_free_bar(const struct pci_epc_features *epc_features);
 enum pci_barno pci_epc_get_next_free_bar(const struct pci_epc_features
 					 *epc_features, enum pci_barno bar);
 struct pci_epc *pci_epc_get(const char *epc_name);
+struct pci_epc *pci_epc_get_fn(bool (*fn)(struct device *dev, void *param), void *param);
 void pci_epc_put(struct pci_epc *epc);
+DEFINE_FREE(pci_epc_put, void *, if (!(_T)) pci_epc_put(_T))
 
 int pci_epc_mem_init(struct pci_epc *epc, phys_addr_t base,
 		     size_t size, size_t page_size);

-- 
2.34.1

[PATCH v6 2/5] PCI: endpoint: Add RC-to-EP doorbell support using platform MSI controller

[Frank Li]

Doorbell feature is implemented by mapping the EP's MSI interrupt
controller message address to a dedicated BAR in the EPC core. It is the
responsibility of the EPF driver to pass the actual message data to be
written by the host to the doorbell BAR region through its own logic.

Tested-by: Niklas Cassel <cassel@kernel.org>
Signed-off-by: Frank Li <Frank.Li@nxp.com>
---
change from v5 to v6
-none

Change from v4 to v5
- Remove request_irq() in pci_epc_alloc_doorbell() and leave to EP function
driver, so ep function driver can register differece call back function for
difference doorbell events and set irq affinity to differece CPU core.
- Improve error message when MSI allocate failure.

Change from v3 to v4
- msi change to use msi_get_virq() avoid use msi_for_each_desc().
- add new struct for pci_epf_doorbell_msg to msi msg,virq and irq name.
- move mutex lock to epc function
- initialize variable at declear place.
- passdown epf to epc*() function to simplify code.
---
 drivers/pci/endpoint/Makefile     |  2 +-
 drivers/pci/endpoint/pci-ep-msi.c | 99 +++++++++++++++++++++++++++++++++++++++
 include/linux/pci-ep-msi.h        | 15 ++++++
 include/linux/pci-epf.h           | 16 +++++++
 4 files changed, 131 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/endpoint/Makefile b/drivers/pci/endpoint/Makefile
index 95b2fe47e3b06..a1ccce440c2c5 100644
--- a/drivers/pci/endpoint/Makefile
+++ b/drivers/pci/endpoint/Makefile
@@ -5,4 +5,4 @@
 
 obj-$(CONFIG_PCI_ENDPOINT_CONFIGFS)	+= pci-ep-cfs.o
 obj-$(CONFIG_PCI_ENDPOINT)		+= pci-epc-core.o pci-epf-core.o\
-					   pci-epc-mem.o functions/
+					   pci-epc-mem.o pci-ep-msi.o functions/
diff --git a/drivers/pci/endpoint/pci-ep-msi.c b/drivers/pci/endpoint/pci-ep-msi.c
new file mode 100644
index 0000000000000..7868a529dce37
--- /dev/null
+++ b/drivers/pci/endpoint/pci-ep-msi.c
@@ -0,0 +1,99 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * PCI Endpoint *Controller* (EPC) MSI library
+ *
+ * Copyright (C) 2024 NXP
+ * Author: Frank Li <Frank.Li@nxp.com>
+ */
+
+#include <linux/cleanup.h>
+#include <linux/device.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/msi.h>
+#include <linux/pci-epc.h>
+#include <linux/pci-epf.h>
+#include <linux/pci-ep-cfs.h>
+#include <linux/pci-ep-msi.h>
+
+static bool pci_epc_match_parent(struct device *dev, void *param)
+{
+	return dev->parent == param;
+}
+
+static void pci_epc_write_msi_msg(struct msi_desc *desc, struct msi_msg *msg)
+{
+	struct pci_epc *epc __free(pci_epc_put) = NULL;
+	struct pci_epf *epf;
+
+	epc = pci_epc_get_fn(pci_epc_match_parent, desc->dev);
+	if (!epc)
+		return;
+
+	/* Only support one EPF for doorbell */
+	epf = list_first_entry_or_null(&epc->pci_epf, struct pci_epf, list);
+
+	if (epf && epf->db_msg && desc->msi_index < epf->num_db)
+		memcpy(&epf->db_msg[desc->msi_index].msg, msg, sizeof(*msg));
+}
+
+static void pci_epc_free_doorbell(struct pci_epc *epc, struct pci_epf *epf)
+{
+	guard(mutex)(&epc->lock);
+
+	platform_device_msi_free_irqs_all(epc->dev.parent);
+}
+
+static int pci_epc_alloc_doorbell(struct pci_epc *epc, struct pci_epf *epf)
+{
+	struct device *dev = epc->dev.parent;
+	u16 num_db = epf->num_db;
+	int i = 0;
+	int ret;
+
+	guard(mutex)(&epc->lock);
+
+	ret = platform_device_msi_init_and_alloc_irqs(dev, num_db, pci_epc_write_msi_msg);
+	if (ret) {
+		dev_err(dev, "Failed to allocate MSI, may miss 'msi-parent' at your DTS\n");
+		return -ENOMEM;
+	}
+
+	for (i = 0; i < num_db; i++)
+		epf->db_msg[i].virq = msi_get_virq(dev, i);
+
+	return 0;
+};
+
+int pci_epf_alloc_doorbell(struct pci_epf *epf, u16 num_db)
+{
+	struct pci_epc *epc = epf->epc;
+	void *msg;
+	int ret;
+
+	msg = kcalloc(num_db, sizeof(struct pci_epf_doorbell_msg), GFP_KERNEL);
+	if (!msg)
+		return -ENOMEM;
+
+	epf->num_db = num_db;
+	epf->db_msg = msg;
+
+	ret = pci_epc_alloc_doorbell(epc, epf);
+	if (ret)
+		kfree(msg);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(pci_epf_alloc_doorbell);
+
+void pci_epf_free_doorbell(struct pci_epf *epf)
+{
+	struct pci_epc *epc = epf->epc;
+
+	pci_epc_free_doorbell(epc, epf);
+
+	kfree(epf->db_msg);
+	epf->db_msg = NULL;
+	epf->num_db = 0;
+}
+EXPORT_SYMBOL_GPL(pci_epf_free_doorbell);
diff --git a/include/linux/pci-ep-msi.h b/include/linux/pci-ep-msi.h
new file mode 100644
index 0000000000000..f0cfecf491199
--- /dev/null
+++ b/include/linux/pci-ep-msi.h
@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * PCI Endpoint *Function* side MSI header file
+ *
+ * Copyright (C) 2024 NXP
+ * Author: Frank Li <Frank.Li@nxp.com>
+ */
+
+#ifndef __PCI_EP_MSI__
+#define __PCI_EP_MSI__
+
+int pci_epf_alloc_doorbell(struct pci_epf *epf, u16 nums);
+void pci_epf_free_doorbell(struct pci_epf *epf);
+
+#endif /* __PCI_EP_MSI__ */
diff --git a/include/linux/pci-epf.h b/include/linux/pci-epf.h
index 18a3aeb62ae4e..5374e6515ffa0 100644
--- a/include/linux/pci-epf.h
+++ b/include/linux/pci-epf.h
@@ -12,6 +12,7 @@
 #include <linux/configfs.h>
 #include <linux/device.h>
 #include <linux/mod_devicetable.h>
+#include <linux/msi.h>
 #include <linux/pci.h>
 
 struct pci_epf;
@@ -125,6 +126,17 @@ struct pci_epf_bar {
 	int		flags;
 };
 
+/**
+ * struct pci_epf_doorbell_msg - represents doorbell message
+ * @msi_msg: MSI message
+ * @virq: irq number of this doorbell MSI message
+ * @name: irq name for doorbell interrupt
+ */
+struct pci_epf_doorbell_msg {
+	struct msi_msg msg;
+	int virq;
+};
+
 /**
  * struct pci_epf - represents the PCI EPF device
  * @dev: the PCI EPF device
@@ -152,6 +164,8 @@ struct pci_epf_bar {
  * @vfunction_num_map: bitmap to manage virtual function number
  * @pci_vepf: list of virtual endpoint functions associated with this function
  * @event_ops: Callbacks for capturing the EPC events
+ * @db_msg: data for MSI from RC side
+ * @num_db: number of doorbells
  */
 struct pci_epf {
 	struct device		dev;
@@ -182,6 +196,8 @@ struct pci_epf {
 	unsigned long		vfunction_num_map;
 	struct list_head	pci_vepf;
 	const struct pci_epc_event_ops *event_ops;
+	struct pci_epf_doorbell_msg *db_msg;
+	u16 num_db;
 };
 
 /**

-- 
2.34.1

[PATCH v6 3/5] PCI: endpoint: pci-epf-test: Add doorbell test support

[Frank Li]

Add three registers: doorbell_bar, doorbell_addr, and doorbell_data,
along with doorbell_done. Use pci_epf_alloc_doorbell() to allocate a
doorbell address space.

Enable the Root Complex (RC) side driver to trigger pci-epc-test's doorbell
callback handler by writing doorbell_data to the mapped doorbell_bar's
address space.

Set doorbell_done in the doorbell callback to indicate completion.

To avoid broken compatibility, add new command COMMAND_ENABLE_DOORBELL
and COMMAND_DISABLE_DOORBELL. Host side need send COMMAND_ENABLE_DOORBELL
to map one bar's inbound address to MSI space. the command
COMMAND_DISABLE_DOORBELL to recovery original inbound address mapping.

	 	Host side new driver	Host side old driver

EP: new driver      S				F
EP: old driver      F				F

S: If EP side support MSI, 'pcitest -B' return success.
   If EP side doesn't support MSI, the same to 'F'.

F: 'pcitest -B' return failure, other case as usual.

Tested-by: Niklas Cassel <cassel@kernel.org>
Signed-off-by: Frank Li <Frank.Li@nxp.com>
---
Change from v5 to v6
- rename doorbell_addr to doorbell_offset

Chagne from v4 to v5
- Add doorbell free at unbind function.
- Move msi irq handler to here to more complex user case, such as differece
doorbell can use difference handler function.
- Add Niklas's code to handle fixed bar's case. If need add your signed-off
tag or co-developer tag, please let me know.

change from v3 to v4
- remove revid requirement
- Add command COMMAND_ENABLE_DOORBELL and COMMAND_DISABLE_DOORBELL.
- call pci_epc_set_bar() to map inbound address to MSI space only at
COMMAND_ENABLE_DOORBELL.
---
 drivers/pci/endpoint/functions/pci-epf-test.c | 129 ++++++++++++++++++++++++++
 1 file changed, 129 insertions(+)

diff --git a/drivers/pci/endpoint/functions/pci-epf-test.c b/drivers/pci/endpoint/functions/pci-epf-test.c
index ef6677f34116e..2d05ab5e4ac6a 100644
--- a/drivers/pci/endpoint/functions/pci-epf-test.c
+++ b/drivers/pci/endpoint/functions/pci-epf-test.c
@@ -11,12 +11,14 @@
 #include <linux/dmaengine.h>
 #include <linux/io.h>
 #include <linux/module.h>
+#include <linux/msi.h>
 #include <linux/slab.h>
 #include <linux/pci_ids.h>
 #include <linux/random.h>
 
 #include <linux/pci-epc.h>
 #include <linux/pci-epf.h>
+#include <linux/pci-ep-msi.h>
 #include <linux/pci_regs.h>
 
 #define IRQ_TYPE_INTX			0
@@ -29,6 +31,8 @@
 #define COMMAND_READ			BIT(3)
 #define COMMAND_WRITE			BIT(4)
 #define COMMAND_COPY			BIT(5)
+#define COMMAND_ENABLE_DOORBELL		BIT(6)
+#define COMMAND_DISABLE_DOORBELL	BIT(7)
 
 #define STATUS_READ_SUCCESS		BIT(0)
 #define STATUS_READ_FAIL		BIT(1)
@@ -39,6 +43,11 @@
 #define STATUS_IRQ_RAISED		BIT(6)
 #define STATUS_SRC_ADDR_INVALID		BIT(7)
 #define STATUS_DST_ADDR_INVALID		BIT(8)
+#define STATUS_DOORBELL_SUCCESS		BIT(9)
+#define STATUS_DOORBELL_ENABLE_SUCCESS	BIT(10)
+#define STATUS_DOORBELL_ENABLE_FAIL	BIT(11)
+#define STATUS_DOORBELL_DISABLE_SUCCESS BIT(12)
+#define STATUS_DOORBELL_DISABLE_FAIL	BIT(13)
 
 #define FLAG_USE_DMA			BIT(0)
 
@@ -74,6 +83,9 @@ struct pci_epf_test_reg {
 	u32	irq_type;
 	u32	irq_number;
 	u32	flags;
+	u32	doorbell_bar;
+	u32	doorbell_offset;
+	u32	doorbell_data;
 } __packed;
 
 static struct pci_epf_header test_header = {
@@ -642,6 +654,63 @@ static void pci_epf_test_raise_irq(struct pci_epf_test *epf_test,
 	}
 }
 
+static void pci_epf_enable_doorbell(struct pci_epf_test *epf_test, struct pci_epf_test_reg *reg)
+{
+	enum pci_barno bar = reg->doorbell_bar;
+	struct pci_epf *epf = epf_test->epf;
+	struct pci_epc *epc = epf->epc;
+	struct pci_epf_bar db_bar;
+	struct msi_msg *msg;
+	u64 doorbell_addr;
+	u32 align;
+	int ret;
+
+	align = epf_test->epc_features->align;
+	align = align ? align : 128;
+
+	if (epf_test->epc_features->bar[bar].type == BAR_FIXED)
+		align = max(epf_test->epc_features->bar[bar].fixed_size, align);
+
+	if (bar < BAR_0 || bar == epf_test->test_reg_bar || !epf->db_msg) {
+		reg->status |= STATUS_DOORBELL_ENABLE_FAIL;
+		return;
+	}
+
+	msg = &epf->db_msg[0].msg;
+	doorbell_addr = msg->address_hi;
+	doorbell_addr <<= 32;
+	doorbell_addr |= msg->address_lo;
+
+	db_bar.phys_addr = round_down(doorbell_addr, align);
+	db_bar.barno = bar;
+	db_bar.size = epf->bar[bar].size;
+	db_bar.flags = epf->bar[bar].flags;
+	db_bar.addr = NULL;
+
+	ret = pci_epc_set_bar(epc, epf->func_no, epf->vfunc_no, &db_bar);
+	if (!ret)
+		reg->status |= STATUS_DOORBELL_ENABLE_SUCCESS;
+}
+
+static void pci_epf_disable_doorbell(struct pci_epf_test *epf_test, struct pci_epf_test_reg *reg)
+{
+	enum pci_barno bar = reg->doorbell_bar;
+	struct pci_epf *epf = epf_test->epf;
+	struct pci_epc *epc = epf->epc;
+	int ret;
+
+	if (bar < BAR_0 || bar == epf_test->test_reg_bar || !epf->db_msg) {
+		reg->status |= STATUS_DOORBELL_DISABLE_FAIL;
+		return;
+	}
+
+	ret = pci_epc_set_bar(epc, epf->func_no, epf->vfunc_no, &epf->bar[bar]);
+	if (ret)
+		reg->status |= STATUS_DOORBELL_DISABLE_FAIL;
+	else
+		reg->status |= STATUS_DOORBELL_DISABLE_SUCCESS;
+}
+
 static void pci_epf_test_cmd_handler(struct work_struct *work)
 {
 	u32 command;
@@ -688,6 +757,14 @@ static void pci_epf_test_cmd_handler(struct work_struct *work)
 		pci_epf_test_copy(epf_test, reg);
 		pci_epf_test_raise_irq(epf_test, reg);
 		break;
+	case COMMAND_ENABLE_DOORBELL:
+		pci_epf_enable_doorbell(epf_test, reg);
+		pci_epf_test_raise_irq(epf_test, reg);
+		break;
+	case COMMAND_DISABLE_DOORBELL:
+		pci_epf_disable_doorbell(epf_test, reg);
+		pci_epf_test_raise_irq(epf_test, reg);
+		break;
 	default:
 		dev_err(dev, "Invalid command 0x%x\n", command);
 		break;
@@ -822,6 +899,18 @@ static int pci_epf_test_link_down(struct pci_epf *epf)
 	return 0;
 }
 
+static irqreturn_t pci_epf_test_doorbell_handler(int irq, void *data)
+{
+	struct pci_epf_test *epf_test = data;
+	enum pci_barno test_reg_bar = epf_test->test_reg_bar;
+	struct pci_epf_test_reg *reg = epf_test->reg[test_reg_bar];
+
+	reg->status |= STATUS_DOORBELL_SUCCESS;
+	pci_epf_test_raise_irq(epf_test, reg);
+
+	return IRQ_HANDLED;
+}
+
 static const struct pci_epc_event_ops pci_epf_test_event_ops = {
 	.epc_init = pci_epf_test_epc_init,
 	.epc_deinit = pci_epf_test_epc_deinit,
@@ -921,12 +1010,46 @@ static int pci_epf_test_bind(struct pci_epf *epf)
 	if (ret)
 		return ret;
 
+	ret = pci_epf_alloc_doorbell(epf, 1);
+	if (!ret) {
+		struct pci_epf_test_reg *reg = epf_test->reg[test_reg_bar];
+		struct msi_msg *msg = &epf->db_msg[0].msg;
+		u32 align = epc_features->align;
+		u64 doorbell_addr;
+		enum pci_barno bar;
+
+		bar = pci_epc_get_next_free_bar(epc_features, test_reg_bar + 1);
+
+		ret = request_irq(epf->db_msg[0].virq, pci_epf_test_doorbell_handler, 0,
+				  "pci-test-doorbell", epf_test);
+		if (ret) {
+			dev_err(&epf->dev,
+				"Failed to request irq %d, doorbell feature is not supported\n",
+				epf->db_msg[0].virq);
+			return 0;
+		}
+
+		align = align ? align : 128;
+
+		if (epf_test->epc_features->bar[bar].type == BAR_FIXED)
+			align = max(epf_test->epc_features->bar[bar].fixed_size, align);
+
+		doorbell_addr = msg->address_hi;
+		doorbell_addr <<= 32;
+		doorbell_addr |= msg->address_lo;
+
+		reg->doorbell_offset = doorbell_addr & (align - 1);
+		reg->doorbell_data = msg->data;
+		reg->doorbell_bar = bar;
+	}
+
 	return 0;
 }
 
 static void pci_epf_test_unbind(struct pci_epf *epf)
 {
 	struct pci_epf_test *epf_test = epf_get_drvdata(epf);
+	struct pci_epf_test_reg *reg = epf_test->reg[epf_test->test_reg_bar];
 	struct pci_epc *epc = epf->epc;
 
 	cancel_delayed_work_sync(&epf_test->cmd_handler);
@@ -934,6 +1057,12 @@ static void pci_epf_test_unbind(struct pci_epf *epf)
 		pci_epf_test_clean_dma_chan(epf_test);
 		pci_epf_test_clear_bar(epf);
 	}
+
+	if (reg->doorbell_bar > 0) {
+		free_irq(epf->db_msg[0].virq, epf_test);
+		pci_epf_free_doorbell(epf);
+	}
+
 	pci_epf_test_free_space(epf);
 }
 

-- 
2.34.1

[PATCH v6 4/5] misc: pci_endpoint_test: Add doorbell test case

[Frank Li]

Add three registers: PCIE_ENDPOINT_TEST_DB_BAR, PCIE_ENDPOINT_TEST_DB_ADDR,
and PCIE_ENDPOINT_TEST_DB_DATA.

Trigger the doorbell by writing data from PCI_ENDPOINT_TEST_DB_DATA to the
address provided by PCI_ENDPOINT_TEST_DB_OFFSET and wait for endpoint
feedback.

Add two command to COMMAND_ENABLE_DOORBELL and COMMAND_DISABLE_DOORBELL
to enable EP side's doorbell support and avoid compatible problem.

		Host side new driver	Host side old driver
EP: new driver		S			F
EP: old driver		F			F

S: If EP side support MSI, 'pcitest -B' return success.
   If EP side doesn't support MSI, the same to 'F'.

F: 'pcitest -B' return failure, other case as usual.

Tested-by: Niklas Cassel <cassel@kernel.org>
Signed-off-by: Frank Li <Frank.Li@nxp.com>
---
Change from v5 to v6
- %s/PCI_ENDPOINT_TEST_DB_ADDR/PCI_ENDPOINT_TEST_DB_OFFSET/g

Change from v4 to v5
- remove unused varible
- add irq_type at pci_endpoint_test_doorbell();

change from v3 to v4
- Add COMMAND_ENABLE_DOORBELL and COMMAND_DISABLE_DOORBELL.
- Remove new DID requirement.
---
 drivers/misc/pci_endpoint_test.c | 71 ++++++++++++++++++++++++++++++++++++++++
 include/uapi/linux/pcitest.h     |  1 +
 2 files changed, 72 insertions(+)

diff --git a/drivers/misc/pci_endpoint_test.c b/drivers/misc/pci_endpoint_test.c
index 3aaaf47fa4ee2..dc766055aa594 100644
--- a/drivers/misc/pci_endpoint_test.c
+++ b/drivers/misc/pci_endpoint_test.c
@@ -42,6 +42,8 @@
 #define COMMAND_READ				BIT(3)
 #define COMMAND_WRITE				BIT(4)
 #define COMMAND_COPY				BIT(5)
+#define COMMAND_ENABLE_DOORBELL			BIT(6)
+#define COMMAND_DISABLE_DOORBELL		BIT(7)
 
 #define PCI_ENDPOINT_TEST_STATUS		0x8
 #define STATUS_READ_SUCCESS			BIT(0)
@@ -53,6 +55,11 @@
 #define STATUS_IRQ_RAISED			BIT(6)
 #define STATUS_SRC_ADDR_INVALID			BIT(7)
 #define STATUS_DST_ADDR_INVALID			BIT(8)
+#define STATUS_DOORBELL_SUCCESS			BIT(9)
+#define STATUS_DOORBELL_ENABLE_SUCCESS		BIT(10)
+#define STATUS_DOORBELL_ENABLE_FAIL		BIT(11)
+#define STATUS_DOORBELL_DISABLE_SUCCESS		BIT(12)
+#define STATUS_DOORBELL_DISABLE_FAIL		BIT(13)
 
 #define PCI_ENDPOINT_TEST_LOWER_SRC_ADDR	0x0c
 #define PCI_ENDPOINT_TEST_UPPER_SRC_ADDR	0x10
@@ -67,6 +74,10 @@
 #define PCI_ENDPOINT_TEST_IRQ_NUMBER		0x28
 
 #define PCI_ENDPOINT_TEST_FLAGS			0x2c
+#define PCI_ENDPOINT_TEST_DB_BAR		0x30
+#define PCI_ENDPOINT_TEST_DB_OFFSET		0x34
+#define PCI_ENDPOINT_TEST_DB_DATA		0x38
+
 #define FLAG_USE_DMA				BIT(0)
 
 #define PCI_DEVICE_ID_TI_AM654			0xb00c
@@ -108,6 +119,7 @@ enum pci_barno {
 	BAR_3,
 	BAR_4,
 	BAR_5,
+	NO_BAR = -1,
 };
 
 struct pci_endpoint_test {
@@ -746,6 +758,62 @@ static bool pci_endpoint_test_set_irq(struct pci_endpoint_test *test,
 	return false;
 }
 
+static bool pci_endpoint_test_doorbell(struct pci_endpoint_test *test)
+{
+	struct pci_dev *pdev = test->pdev;
+	struct device *dev = &pdev->dev;
+	int irq_type = test->irq_type;
+	enum pci_barno bar;
+	u32 data, status;
+	u32 addr;
+
+	if (irq_type < IRQ_TYPE_INTX || irq_type > IRQ_TYPE_MSIX) {
+		dev_err(dev, "Invalid IRQ type option\n");
+		return false;
+	}
+
+	pci_endpoint_test_writel(test, PCI_ENDPOINT_TEST_IRQ_TYPE, irq_type);
+	pci_endpoint_test_writel(test, PCI_ENDPOINT_TEST_IRQ_NUMBER, 1);
+	pci_endpoint_test_writel(test, PCI_ENDPOINT_TEST_COMMAND,
+				 COMMAND_ENABLE_DOORBELL);
+
+	wait_for_completion_timeout(&test->irq_raised, msecs_to_jiffies(1000));
+
+	status = pci_endpoint_test_readl(test, PCI_ENDPOINT_TEST_STATUS);
+	if (status & STATUS_DOORBELL_ENABLE_FAIL)
+		return false;
+
+	data = pci_endpoint_test_readl(test, PCI_ENDPOINT_TEST_DB_DATA);
+	addr = pci_endpoint_test_readl(test, PCI_ENDPOINT_TEST_DB_OFFSET);
+	bar = pci_endpoint_test_readl(test, PCI_ENDPOINT_TEST_DB_BAR);
+
+	pci_endpoint_test_writel(test, PCI_ENDPOINT_TEST_IRQ_TYPE, irq_type);
+	pci_endpoint_test_writel(test, PCI_ENDPOINT_TEST_IRQ_NUMBER, 1);
+
+	pci_endpoint_test_writel(test, PCI_ENDPOINT_TEST_STATUS, 0);
+
+	bar = pci_endpoint_test_readl(test, PCI_ENDPOINT_TEST_DB_BAR);
+
+	writel(data, test->bar[bar] + addr);
+
+	wait_for_completion_timeout(&test->irq_raised, msecs_to_jiffies(1000));
+
+	status = pci_endpoint_test_readl(test, PCI_ENDPOINT_TEST_STATUS);
+
+	pci_endpoint_test_writel(test, PCI_ENDPOINT_TEST_COMMAND,
+				 COMMAND_DISABLE_DOORBELL);
+
+	wait_for_completion_timeout(&test->irq_raised, msecs_to_jiffies(1000));
+
+	status |= pci_endpoint_test_readl(test, PCI_ENDPOINT_TEST_STATUS);
+
+	if ((status & STATUS_DOORBELL_SUCCESS) &&
+	    (status & STATUS_DOORBELL_DISABLE_SUCCESS))
+		return true;
+
+	return false;
+}
+
 static long pci_endpoint_test_ioctl(struct file *file, unsigned int cmd,
 				    unsigned long arg)
 {
@@ -793,6 +861,9 @@ static long pci_endpoint_test_ioctl(struct file *file, unsigned int cmd,
 	case PCITEST_CLEAR_IRQ:
 		ret = pci_endpoint_test_clear_irq(test);
 		break;
+	case PCITEST_DOORBELL:
+		ret = pci_endpoint_test_doorbell(test);
+		break;
 	}
 
 ret:
diff --git a/include/uapi/linux/pcitest.h b/include/uapi/linux/pcitest.h
index 94b46b043b536..06d9f548b510e 100644
--- a/include/uapi/linux/pcitest.h
+++ b/include/uapi/linux/pcitest.h
@@ -21,6 +21,7 @@
 #define PCITEST_SET_IRQTYPE	_IOW('P', 0x8, int)
 #define PCITEST_GET_IRQTYPE	_IO('P', 0x9)
 #define PCITEST_CLEAR_IRQ	_IO('P', 0x10)
+#define PCITEST_DOORBELL	_IO('P', 0x11)
 
 #define PCITEST_FLAGS_USE_DMA	0x00000001
 

-- 
2.34.1

[PATCH v6 5/5] tools: PCI: Add 'B' option for test doorbell

[Frank Li]

Add doorbell test support.

Tested-by: Niklas Cassel <cassel@kernel.org>
Signed-off-by: Frank Li <Frank.Li@nxp.com>
---
Change from v3 to v6
- none
---
 tools/pci/pcitest.c | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/tools/pci/pcitest.c b/tools/pci/pcitest.c
index 470258009ddc2..bbe26ebbfd945 100644
--- a/tools/pci/pcitest.c
+++ b/tools/pci/pcitest.c
@@ -34,6 +34,7 @@ struct pci_test {
 	bool		copy;
 	unsigned long	size;
 	bool		use_dma;
+	bool		doorbell;
 };
 
 static int run_test(struct pci_test *test)
@@ -147,6 +148,15 @@ static int run_test(struct pci_test *test)
 			fprintf(stdout, "%s\n", result[ret]);
 	}
 
+	if (test->doorbell) {
+		ret = ioctl(fd, PCITEST_DOORBELL, 0);
+		fprintf(stdout, "Ringing doorbell on the EP\t\t");
+		if (ret < 0)
+			fprintf(stdout, "TEST FAILED\n");
+		else
+			fprintf(stdout, "%s\n", result[ret]);
+	}
+
 	fflush(stdout);
 	close(fd);
 	return (ret < 0) ? ret : 1 - ret; /* return 0 if test succeeded */
@@ -172,7 +182,7 @@ int main(int argc, char **argv)
 	/* set default endpoint device */
 	test->device = "/dev/pci-endpoint-test.0";
 
-	while ((c = getopt(argc, argv, "D:b:m:x:i:deIlhrwcs:")) != EOF)
+	while ((c = getopt(argc, argv, "D:b:m:x:i:BdeIlhrwcs:")) != EOF)
 	switch (c) {
 	case 'D':
 		test->device = optarg;
@@ -222,6 +232,9 @@ int main(int argc, char **argv)
 	case 'd':
 		test->use_dma = true;
 		continue;
+	case 'B':
+		test->doorbell = true;
+		continue;
 	case 'h':
 	default:
 usage:
@@ -241,6 +254,7 @@ int main(int argc, char **argv)
 			"\t-w			Write buffer test\n"
 			"\t-c			Copy buffer test\n"
 			"\t-s <size>		Size of buffer {default: 100KB}\n"
+			"\t-B			Doorbell test\n"
 			"\t-h			Print this help message\n",
 			argv[0]);
 		return -EINVAL;

-- 
2.34.1

Re: [PATCH v6 3/5] PCI: endpoint: pci-epf-test: Add doorbell test support

[Niklas Cassel]

Hello Frank,

On Tue, Nov 12, 2024 at 12:48:16PM -0500, Frank Li wrote:
> Add three registers: doorbell_bar, doorbell_addr, and doorbell_data,
> along with doorbell_done. Use pci_epf_alloc_doorbell() to allocate a
> doorbell address space.
> 
> Enable the Root Complex (RC) side driver to trigger pci-epc-test's doorbell
> callback handler by writing doorbell_data to the mapped doorbell_bar's
> address space.
> 
> Set doorbell_done in the doorbell callback to indicate completion.
> 
> To avoid broken compatibility, add new command COMMAND_ENABLE_DOORBELL
> and COMMAND_DISABLE_DOORBELL. Host side need send COMMAND_ENABLE_DOORBELL
> to map one bar's inbound address to MSI space. the command
> COMMAND_DISABLE_DOORBELL to recovery original inbound address mapping.
> 
> 	 	Host side new driver	Host side old driver
> 
> EP: new driver      S				F
> EP: old driver      F				F
> 
> S: If EP side support MSI, 'pcitest -B' return success.
>    If EP side doesn't support MSI, the same to 'F'.
> 
> F: 'pcitest -B' return failure, other case as usual.
> 
> Tested-by: Niklas Cassel <cassel@kernel.org>
> Signed-off-by: Frank Li <Frank.Li@nxp.com>
> ---
> Change from v5 to v6
> - rename doorbell_addr to doorbell_offset

Is there a reason why you chose to not incorporate the helper function
that I suggested here:
https://lore.kernel.org/linux-pci/ZzMtKUFi30_o6SwL@ryzen/

I didn't see any reply from you to that message.

Personally I think that it is nice to have the alignment code in a single
function, rather than duplicating the code. The helper also looks quite
similar to how we do outbound address translation alignment:
https://git.kernel.org/pub/scm/linux/kernel/git/pci/pci.git/commit/?h=endpoint&id=e73ea1c2d4d8f7ba5daaf7aa51171f63cf79bcd8
so that people will recognize the pattern more easily.

But I guess you didn't like my suggestion?
(Which is fine, but I would have expected some motivation.)


Kind regards,
Niklas

Re: [PATCH v6 3/5] PCI: endpoint: pci-epf-test: Add doorbell test support

[Frank Li]

On Tue, Nov 12, 2024 at 09:14:49PM +0100, Niklas Cassel wrote:
> Hello Frank,
>
> On Tue, Nov 12, 2024 at 12:48:16PM -0500, Frank Li wrote:
> > Add three registers: doorbell_bar, doorbell_addr, and doorbell_data,
> > along with doorbell_done. Use pci_epf_alloc_doorbell() to allocate a
> > doorbell address space.
> >
> > Enable the Root Complex (RC) side driver to trigger pci-epc-test's doorbell
> > callback handler by writing doorbell_data to the mapped doorbell_bar's
> > address space.
> >
> > Set doorbell_done in the doorbell callback to indicate completion.
> >
> > To avoid broken compatibility, add new command COMMAND_ENABLE_DOORBELL
> > and COMMAND_DISABLE_DOORBELL. Host side need send COMMAND_ENABLE_DOORBELL
> > to map one bar's inbound address to MSI space. the command
> > COMMAND_DISABLE_DOORBELL to recovery original inbound address mapping.
> >
> > 	 	Host side new driver	Host side old driver
> >
> > EP: new driver      S				F
> > EP: old driver      F				F
> >
> > S: If EP side support MSI, 'pcitest -B' return success.
> >    If EP side doesn't support MSI, the same to 'F'.
> >
> > F: 'pcitest -B' return failure, other case as usual.
> >
> > Tested-by: Niklas Cassel <cassel@kernel.org>
> > Signed-off-by: Frank Li <Frank.Li@nxp.com>
> > ---
> > Change from v5 to v6
> > - rename doorbell_addr to doorbell_offset
>
> Is there a reason why you chose to not incorporate the helper function
> that I suggested here:
> https://lore.kernel.org/linux-pci/ZzMtKUFi30_o6SwL@ryzen/
>
> I didn't see any reply from you to that message.

Oh, you said at
https://lore.kernel.org/imx/ZzIVzfkZe-hkAb4G@ryzen/T/#mc10e69e0e1e20cc8d8da9a8808177407d22bce06

I think you give up your idea about helper function, because it is one
for doorbell_offset, the other is for the atu address. bar's struct is
difference with reg. even it is similar,

one if use "addr & (align - 1)" to get offset, the other is "addr & ~algin"
to get base address.

>
> Personally I think that it is nice to have the alignment code in a single
> function, rather than duplicating the code. The helper also looks quite
> similar to how we do outbound address translation alignment:
> https://git.kernel.org/pub/scm/linux/kernel/git/pci/pci.git/commit/?h=endpoint&id=e73ea1c2d4d8f7ba5daaf7aa51171f63cf79bcd8
> so that people will recognize the pattern more easily.

Do you means add help function, which wrap epc's .align_addr()? I know you
make some improvement about EP's alignment, but I have not realized that
related this thread at all.

>
> But I guess you didn't like my suggestion?
> (Which is fine, but I would have expected some motivation.)

May "I now see why you did this.
One function is using the db offset, and the other is using the db base."
mis-lead me.

If I understand correct here, I can add wrap function for epc's
.align_addr(). at next version.

Frank
>
>
> Kind regards,
> Niklas

Re: [PATCH v6 3/5] PCI: endpoint: pci-epf-test: Add doorbell test support

[Niklas Cassel]

On Tue, Nov 12, 2024 at 03:37:34PM -0500, Frank Li wrote:
> >
> > Is there a reason why you chose to not incorporate the helper function
> > that I suggested here:
> > https://lore.kernel.org/linux-pci/ZzMtKUFi30_o6SwL@ryzen/
> >
> > I didn't see any reply from you to that message.
> 
> Oh, you said at
> https://lore.kernel.org/imx/ZzIVzfkZe-hkAb4G@ryzen/T/#mc10e69e0e1e20cc8d8da9a8808177407d22bce06
> 
> I think you give up your idea about helper function, because it is one
> for doorbell_offset, the other is for the atu address. bar's struct is
> difference with reg. even it is similar,

Yes, that is why the helper returns both base addess and offset
(just like .align_addr()).


> Do you means add help function, which wrap epc's .align_addr()? I know you
> make some improvement about EP's alignment, but I have not realized that
> related this thread at all.

Look at the suggested helper that I wrote in:
https://lore.kernel.org/linux-pci/ZzMtKUFi30_o6SwL@ryzen/

If you think that the code is cleaner, feel free to incorporate it in your
next version, no need to add my SoB.

.align_addr() is not related at all.
(.align_addr() is for alignment for outbound PCI address, and theoretically
the alignment requirement for outbound could be different from inbound
address alignment requirement (which is defined in epc->features->align).

The only relation is that both my suggested helper, and .align_addr() both
return a base address and an offset.


> May "I now see why you did this.
> One function is using the db offset, and the other is using the db base."
> mis-lead me.

Yes, I can see that this sentence can be misunderstood.


> If I understand correct here, I can add wrap function for epc's
> .align_addr(). at next version.

Please do not wrap .align_addr(). Kishon has been very clear that he wants
outbound and inbound translation requirements to not depend on each other.


Kind regards,
Niklas