[RFC PATCH v4 4/4] cxl/pci: Add support for stand alone CXL Switch mailbox CCI

[Jonathan Cameron <Jonathan.Cameron@huawei.com>]

CXL 3.0 defines a mailbox PCI function independent of any other CXL
components. The intent is that instances of this mailbox will be found
as additional PCI functions of upstream CXL switch ports.

Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
---
 drivers/cxl/Kconfig           |  14 +++
 drivers/cxl/Makefile          |   2 +
 drivers/cxl/core/Makefile     |   1 +
 drivers/cxl/core/core.h       |   1 +
 drivers/cxl/core/mbox.c       |   6 ++
 drivers/cxl/core/port.c       |   4 +
 drivers/cxl/core/switch-cci.c | 144 +++++++++++++++++++++++++++
 drivers/cxl/cxlmem.h          |  15 +++
 drivers/cxl/switch-cci.c      | 181 ++++++++++++++++++++++++++++++++++
 include/uapi/linux/cxl_mem.h  |   4 +
 10 files changed, 372 insertions(+)

diff --git a/drivers/cxl/Kconfig b/drivers/cxl/Kconfig
index fcbf8295fde3..9a304ab60692 100644
--- a/drivers/cxl/Kconfig
+++ b/drivers/cxl/Kconfig
@@ -152,5 +152,19 @@ config CXL_PMU
 	  Say 'y/m' to enable a driver that will attach to performance
 	  monitoring units and provide standard perf based interfaces.
 
+	  If unsure say 'm'.
+
+config CXL_SWITCH
+	tristate "CXL switch mailbox access"
+	help
+	  The CXL r3.0 specification defines a "CXL switch CCI" sub-class in the
+	  PCI "Serial" base class of devices. Device's identified by
+	  this class code provide a mailbox interface to allow control of CXL
+	  switch configuration over inband PCI.
+
+	  Say 'y/m' to enable a driver that will attach to CXL Switch CCI
+	  devices enumerated by the CXL switch CCI class code for configuration
+	  and management primarily via the mailbox interface.
+
 	  If unsure say 'm'.
 endif
diff --git a/drivers/cxl/Makefile b/drivers/cxl/Makefile
index db321f48ba52..1e5f5b8b4d73 100644
--- a/drivers/cxl/Makefile
+++ b/drivers/cxl/Makefile
@@ -5,9 +5,11 @@ obj-$(CONFIG_CXL_MEM) += cxl_mem.o
 obj-$(CONFIG_CXL_ACPI) += cxl_acpi.o
 obj-$(CONFIG_CXL_PMEM) += cxl_pmem.o
 obj-$(CONFIG_CXL_PORT) += cxl_port.o
+obj-$(CONFIG_CXL_SWITCH) += cxl_switch_cci.o
 
 cxl_mem-y := mem.o
 cxl_pci-y := pci.o
 cxl_acpi-y := acpi.o
 cxl_pmem-y := pmem.o security.o
 cxl_port-y := port.o
+cxl_switch_cci-y := switch-cci.o
diff --git a/drivers/cxl/core/Makefile b/drivers/cxl/core/Makefile
index 1f66b5d4d935..d8a0ffa0f8cc 100644
--- a/drivers/cxl/core/Makefile
+++ b/drivers/cxl/core/Makefile
@@ -13,5 +13,6 @@ cxl_core-y += mbox.o
 cxl_core-y += pci.o
 cxl_core-y += hdm.o
 cxl_core-y += pmu.o
+cxl_core-y += switch-cci.o
 cxl_core-$(CONFIG_TRACING) += trace.o
 cxl_core-$(CONFIG_CXL_REGION) += region.o
diff --git a/drivers/cxl/core/core.h b/drivers/cxl/core/core.h
index 5491d3a3c095..23d21d290db5 100644
--- a/drivers/cxl/core/core.h
+++ b/drivers/cxl/core/core.h
@@ -80,6 +80,7 @@ extern struct rw_semaphore cxl_dpa_rwsem;
 int cxl_memdev_init(void);
 void cxl_memdev_exit(void);
 void cxl_mbox_init(void);
+int cxl_switch_cci_init(void);
 
 enum cxl_poison_trace_type {
 	CXL_POISON_TRACE_LIST,
diff --git a/drivers/cxl/core/mbox.c b/drivers/cxl/core/mbox.c
index 5ee6ecfb572d..378f345fdee6 100644
--- a/drivers/cxl/core/mbox.c
+++ b/drivers/cxl/core/mbox.c
@@ -9,6 +9,7 @@
 #include <cxlmbox.h>
 #include <cxlpci.h>
 #include <cxlmem.h>
+#include <cxlpci.h>
 #include <cxl.h>
 
 #include "core.h"
@@ -56,6 +57,8 @@ static bool cxl_raw_allow_all;
  * 0, and the user passed in 1, it is an error.
  */
 static struct cxl_mem_command cxl_mem_commands[CXL_MEM_COMMAND_ID_MAX] = {
+	CXL_CMD(INFO_STAT_IDENTIFY, 0, 0x12, 0),
+	CXL_CMD(GET_BG_CMD_STATUS, 0, 8, 0),
 	CXL_CMD(IDENTIFY, 0, 0x43, CXL_CMD_FLAG_FORCE_ENABLE),
 #ifdef CONFIG_CXL_MEM_RAW_COMMANDS
 	CXL_CMD(RAW, CXL_VARIABLE_PAYLOAD, CXL_VARIABLE_PAYLOAD, 0),
@@ -73,6 +76,9 @@ static struct cxl_mem_command cxl_mem_commands[CXL_MEM_COMMAND_ID_MAX] = {
 	CXL_CMD(GET_SHUTDOWN_STATE, 0, 0x1, 0),
 	CXL_CMD(SET_SHUTDOWN_STATE, 0x1, 0, 0),
 	CXL_CMD(GET_SCAN_MEDIA_CAPS, 0x10, 0x4, 0),
+	CXL_CMD(IDENTIFY_SWITCH_DEVICE, 0, 0x49, 0),
+	CXL_CMD(TUNNEL_MANAGEMENT_COMMAND, CXL_VARIABLE_PAYLOAD,
+		CXL_VARIABLE_PAYLOAD, 0),
 };
 
 /*
diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c
index 724be8448eb4..ce3fb0d406d7 100644
--- a/drivers/cxl/core/port.c
+++ b/drivers/cxl/core/port.c
@@ -2020,6 +2020,10 @@ static __init int cxl_core_init(void)
 	if (rc)
 		return rc;
 
+	rc = cxl_switch_cci_init();
+	if (rc)
+		return rc;
+
 	cxl_bus_wq = alloc_ordered_workqueue("cxl_port", 0);
 	if (!cxl_bus_wq) {
 		rc = -ENOMEM;
diff --git a/drivers/cxl/core/switch-cci.c b/drivers/cxl/core/switch-cci.c
new file mode 100644
index 000000000000..874622d8e952
--- /dev/null
+++ b/drivers/cxl/core/switch-cci.c
@@ -0,0 +1,144 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include "cxlmem.h" /* For now to get the cxl_device_state */
+#include "cxlpci.h"
+#include "core.h"
+
+static int cxl_sw_major;
+static DEFINE_IDA(cxl_swdev_ida);
+static DECLARE_RWSEM(cxl_swdev_rwsem);
+
+static inline struct cxl_swdev *to_cxl_swdev(struct device *dev)
+{
+	return container_of(dev, struct cxl_swdev, dev);
+}
+
+static char *cxl_swdev_devnode(const struct device *dev, umode_t *mode, kuid_t *uid,
+			kgid_t *gid)
+{
+	return kasprintf(GFP_KERNEL, "cxl/%s", dev_name(dev));
+}
+
+static long __cxl_swdev_ioctl(struct cxl_swdev *cxlswd, unsigned int cmd,
+			       unsigned long arg)
+{
+	switch (cmd) {
+	case CXL_MEM_SEND_COMMAND:
+		return cxl_send_cmd(&cxlswd->mbox, (void __user *)arg);
+	default:
+		return -ENOTTY;
+	}
+}
+
+static long cxl_swdev_ioctl(struct file *file, unsigned int cmd,
+			    unsigned long arg)
+{
+	struct cxl_swdev *cxlswd = file->private_data;
+	int rc = -ENXIO;
+
+	down_read(&cxl_swdev_rwsem);
+	rc = __cxl_swdev_ioctl(cxlswd, cmd, arg);
+	up_read(&cxl_swdev_rwsem);
+
+	return rc;
+}
+
+static int cxl_swdev_open(struct inode *inode, struct file *file)
+{
+	struct cxl_memdev *cxlswd =
+		container_of(inode->i_cdev, typeof(*cxlswd), cdev);
+
+	get_device(&cxlswd->dev);
+	file->private_data = cxlswd;
+
+	return 0;
+}
+
+static int cxl_swdev_release_file(struct inode *inode, struct file *file)
+{
+	struct cxl_swdev *cxlswd =
+		container_of(inode->i_cdev, typeof(*cxlswd), cdev);
+
+	put_device(&cxlswd->dev);
+
+	return 0;
+}
+
+static const struct file_operations cxl_swdev_fops = {
+	.owner = THIS_MODULE,
+	.unlocked_ioctl = cxl_swdev_ioctl,
+	.open = cxl_swdev_open,
+	.release = cxl_swdev_release_file,
+	.compat_ioctl = compat_ptr_ioctl,
+	.llseek = noop_llseek,
+};
+
+void cxl_swdev_shutdown(struct cxl_swdev *cxlswd)
+{
+	down_write(&cxl_swdev_rwsem);
+	up_write(&cxl_swdev_rwsem);
+}
+EXPORT_SYMBOL_NS_GPL(cxl_swdev_shutdown, CXL);
+
+static void cxl_swdev_release(struct device *dev)
+{
+	struct cxl_swdev *cxlswd = to_cxl_swdev(dev);
+
+	ida_free(&cxl_swdev_ida, cxlswd->id);
+	kfree(cxlswd);
+}
+
+static const struct device_type cxl_swdev_type = {
+	.name = "cxl_swdev",
+	.release = cxl_swdev_release,
+	.devnode = cxl_swdev_devnode,
+};
+
+struct cxl_swdev *cxl_swdev_alloc(struct device *parent)
+{
+	struct cxl_swdev *cxlswd;
+	struct device *dev;
+	struct cdev *cdev;
+	int rc;
+
+	cxlswd = kzalloc(sizeof(*cxlswd), GFP_KERNEL);
+	if (!cxlswd)
+		return ERR_PTR(-ENOMEM);
+
+	rc = ida_alloc_range(&cxl_swdev_ida, 0, 10, GFP_KERNEL);
+	if (rc < 0) {
+		kfree(cxlswd);
+		return ERR_PTR(rc);
+	}
+
+	cxlswd->id = rc;
+	dev = &cxlswd->dev;
+	device_initialize(dev);
+	dev->bus = &cxl_bus_type;
+	dev->parent = parent;
+	dev->devt = MKDEV(cxl_sw_major, cxlswd->id);
+	dev->type = &cxl_swdev_type;
+	device_set_pm_not_required(dev);
+	cdev = &cxlswd->cdev;
+	cdev_init(cdev, &cxl_swdev_fops);
+	rc = dev_set_name(dev, "swcci%d", cxlswd->id);
+	if (rc) {
+		put_device(dev);
+		return ERR_PTR(rc);
+	}
+
+	return cxlswd;
+}
+EXPORT_SYMBOL_NS_GPL(cxl_swdev_alloc, CXL);
+
+__init int cxl_switch_cci_init(void)
+{
+	dev_t devt;
+	int rc;
+
+	rc = alloc_chrdev_region(&devt, 0, 10, "cxlsw");
+	if (rc)
+		return rc;
+	cxl_sw_major = MAJOR(devt);
+
+	return 0;
+}
diff --git a/drivers/cxl/cxlmem.h b/drivers/cxl/cxlmem.h
index edc173715814..b0e7fbdbcfb3 100644
--- a/drivers/cxl/cxlmem.h
+++ b/drivers/cxl/cxlmem.h
@@ -456,6 +456,17 @@ struct cxl_memdev_state {
 	struct cxl_fw_state fw;
 };
 
+struct cxl_swdev {
+	struct device dev;
+	struct cdev cdev;
+	struct cxl_mbox mbox;
+	struct cxl_dev_state cxlds;
+	int id;
+};
+
+struct cxl_swdev *cxl_swdev_alloc(struct device *parent);
+void cxl_swdev_shutdown(struct cxl_swdev *cxlswd);
+
 static inline struct cxl_memdev_state *
 to_cxl_memdev_state(struct cxl_dev_state *cxlds)
 {
@@ -466,6 +477,8 @@ to_cxl_memdev_state(struct cxl_dev_state *cxlds)
 
 enum cxl_opcode {
 	CXL_MBOX_OP_INVALID		= 0x0000,
+	CXL_MBOX_OP_INFO_STAT_IDENTIFY	= 0x0001,
+	CXL_MBOX_OP_GET_BG_CMD_STATUS	= 0x0002,
 	CXL_MBOX_OP_RAW			= CXL_MBOX_OP_INVALID,
 	CXL_MBOX_OP_GET_EVENT_RECORD	= 0x0100,
 	CXL_MBOX_OP_CLEAR_EVENT_RECORD	= 0x0101,
@@ -501,6 +514,8 @@ enum cxl_opcode {
 	CXL_MBOX_OP_UNLOCK		= 0x4503,
 	CXL_MBOX_OP_FREEZE_SECURITY	= 0x4504,
 	CXL_MBOX_OP_PASSPHRASE_SECURE_ERASE	= 0x4505,
+	CXL_MBOX_OP_IDENTIFY_SWITCH_DEVICE	= 0x5100,
+	CXL_MBOX_OP_TUNNEL_MANAGEMENT_COMMAND	= 0x5300,
 	CXL_MBOX_OP_MAX			= 0x10000
 };
 
diff --git a/drivers/cxl/switch-cci.c b/drivers/cxl/switch-cci.c
new file mode 100644
index 000000000000..a8c5ea8f4436
--- /dev/null
+++ b/drivers/cxl/switch-cci.c
@@ -0,0 +1,181 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright(c) Huawei Technologies
+ * Based on cxl/pci.c Copyright(c) 2020 Intel Corporation. All rights reserved.
+ */
+
+#include <linux/io-64-nonatomic-lo-hi.h>
+#include <linux/moduleparam.h>
+#include <linux/module.h>
+#include <linux/delay.h>
+#include <linux/sizes.h>
+#include <linux/mutex.h>
+#include <linux/list.h>
+#include <linux/pci.h>
+#include <linux/io.h>
+#include "cxlmem.h"
+#include "cxlpci.h"
+#include "cxl.h"
+
+static irqreturn_t cxl_swmbcci_mbox_irq(int irq, void *d)
+{
+	return cxl_mbox_irq(irq, d);
+}
+
+static int cxl_swmbcci_setup_mailbox(struct cxl_mbox *mbox)
+{
+	const int cap = readl(mbox->mbox + CXLDEV_MBOX_CAPS_OFFSET);
+
+	/*
+	 * A command may be in flight from a previous driver instance,
+	 * think kexec, do one doorbell wait so that
+	 * __cxl_pci_mbox_send_cmd() can assume that it is the only
+	 * source for future doorbell busy events.
+	 */
+	if (cxl_pci_mbox_wait_for_doorbell(mbox) != 0) {
+		u64 md_status = 0;
+
+		if (mbox->get_status)
+			md_status = mbox->get_status(mbox);
+		cxl_err(mbox->dev, md_status, "timeout awaiting mailbox idle");
+
+		return -ETIMEDOUT;
+	}
+
+	mbox->payload_size =
+		1 << FIELD_GET(CXLDEV_MBOX_CAP_PAYLOAD_SIZE_MASK, cap);
+
+	/*
+	 * CXL 2.0 8.2.8.4.3 Mailbox Capabilities Register
+	 *
+	 * If the size is too small, mandatory commands will not work and so
+	 * there's no point in going forward. If the size is too large, there's
+	 * no harm is soft limiting it.
+	 */
+	mbox->payload_size = min_t(size_t, mbox->payload_size, SZ_1M);
+	if (mbox->payload_size < 256) {
+		dev_err(mbox->dev, "Mailbox is too small (%zub)",
+			mbox->payload_size);
+		return -ENXIO;
+	}
+
+	dev_dbg(mbox->dev, "Mailbox payload sized %zu", mbox->payload_size);
+
+	rcuwait_init(&mbox->mbox_wait);
+
+	if (cap & CXLDEV_MBOX_CAP_BG_CMD_IRQ) {
+		u32 ctrl;
+		int irq, msgnum, rc;
+		struct pci_dev *pdev = to_pci_dev(mbox->dev);
+
+		msgnum = FIELD_GET(CXLDEV_MBOX_CAP_IRQ_MSGNUM_MASK, cap);
+		irq = pci_irq_vector(pdev, msgnum);
+		if (irq < 0)
+			goto mbox_poll;
+
+		rc = devm_request_threaded_irq(mbox->dev, irq, cxl_swmbcci_mbox_irq,
+					       NULL, IRQF_SHARED | IRQF_ONESHOT,
+					       NULL, mbox);
+		if (rc)
+			goto mbox_poll;
+
+		/* enable background command mbox irq support */
+		ctrl = readl(mbox->mbox + CXLDEV_MBOX_CTRL_OFFSET);
+		ctrl |= CXLDEV_MBOX_CTRL_BG_CMD_IRQ;
+		writel(ctrl, mbox->mbox + CXLDEV_MBOX_CTRL_OFFSET);
+
+		return 0;
+	}
+
+mbox_poll:
+	if (mbox->special_init_poll)
+		mbox->special_init_poll(mbox);
+
+	dev_dbg(mbox->dev, "Mailbox interrupts are unsupported");
+	return 0;
+}
+
+
+static int cxl_swmbcci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
+{
+	struct cxl_register_map map;
+	struct cxl_swdev *cxlswd;
+	int rc;
+
+	rc = pcim_enable_device(pdev);
+	if (rc)
+		return rc;
+
+	cxlswd = cxl_swdev_alloc(&pdev->dev);
+	if (IS_ERR(cxlswd))
+		return PTR_ERR(cxlswd);
+
+	mutex_init(&cxlswd->mbox.mbox_mutex);
+	rc = cxl_find_regblock(pdev, CXL_REGLOC_RBI_MEMDEV, &map);
+	if (rc)
+		return rc;
+	rc = cxl_setup_regs(&map);
+	if (rc)
+		return rc;
+
+	rc = cxl_map_device_regs(&map, &cxlswd->cxlds.regs.device_regs);
+	if (rc)
+		return rc;
+
+	rc = cxl_map_mbox_regs(&map, &cxlswd->mbox.mbox);
+	if (rc)
+		return rc;
+
+	cxlswd->mbox.status = cxlswd->cxlds.regs.status;
+	cxlswd->mbox.dev = &pdev->dev;
+
+	rc = cxl_swmbcci_setup_mailbox(&cxlswd->mbox);
+	if (rc)
+		return rc;
+
+
+	pci_set_drvdata(pdev, cxlswd);
+
+	rc = cxl_enumerate_cmds(&cxlswd->mbox);
+	if (rc)
+		goto error_put_device;
+
+	rc = cdev_device_add(&cxlswd->cdev, &cxlswd->dev);
+	if (rc)
+		goto error_put_device;
+
+	return 0;
+
+error_put_device:
+	cxl_swdev_shutdown(cxlswd);
+	put_device(&cxlswd->dev);
+	return rc;
+}
+
+static void cxl_swbmcci_remove(struct pci_dev *pdev)
+{
+	struct cxl_swdev *cxlswd = pci_get_drvdata(pdev);
+	struct device *dev = &cxlswd->dev;
+
+	cxl_swdev_shutdown(cxlswd);
+	cdev_device_del(&cxlswd->cdev, dev);
+	put_device(&cxlswd->dev);
+}
+
+static const struct pci_device_id cxl_swmbcci_pci_tbl[] = {
+	{ PCI_DEVICE_CLASS(PCI_CLASS_SERIAL_CXL_SWITCH_CCI, ~0) },
+	{}
+};
+MODULE_DEVICE_TABLE(pci, cxl_swmbcci_pci_tbl);
+
+static struct pci_driver cxl_swmbcci_driver = {
+	.name = KBUILD_MODNAME,
+	.id_table = cxl_swmbcci_pci_tbl,
+	.probe = cxl_swmbcci_probe,
+	.remove = cxl_swbmcci_remove,
+};
+
+module_pci_driver(cxl_swmbcci_driver);
+MODULE_DESCRIPTION("CXL Switch CCI mailbox access driver");
+MODULE_LICENSE("GPL");
+MODULE_IMPORT_NS(CXL);
diff --git a/include/uapi/linux/cxl_mem.h b/include/uapi/linux/cxl_mem.h
index 14bc6e742148..b62aeba9d5c6 100644
--- a/include/uapi/linux/cxl_mem.h
+++ b/include/uapi/linux/cxl_mem.h
@@ -46,6 +46,10 @@
 	___C(GET_SCAN_MEDIA_CAPS, "Get Scan Media Capabilities"),         \
 	___DEPRECATED(SCAN_MEDIA, "Scan Media"),                          \
 	___DEPRECATED(GET_SCAN_MEDIA, "Get Scan Media Results"),          \
+	___C(INFO_STAT_IDENTIFY, "Get Information"),			  \
+	___C(GET_BG_CMD_STATUS, "Background Command Status"),	\
+	___C(IDENTIFY_SWITCH_DEVICE, "Identify Switch Device"),		\
+	___C(TUNNEL_MANAGEMENT_COMMAND, "Tunnel Management Command"),     \
 	___C(MAX, "invalid / last command")
 
 #define ___C(a, b) CXL_MEM_COMMAND_ID_##a
-- 
2.39.2