Merge branch 'iosm-driver'

M Chetan Kumar says:

====================
net: iosm: PCIe Driver for Intel M.2 Modem

The IOSM (IPC over Shared Memory) driver is a PCIe host driver implemented
for linux or chrome platform for data exchange over PCIe interface between
Host platform & Intel M.2 Modem. The driver exposes interface conforming to
the MBIM protocol. Any front end application ( eg: Modem Manager) could
easily manage the MBIM interface to enable data communication towards WWAN.

Intel M.2 modem uses 2 BAR regions. The first region is dedicated to Doorbell
register for IRQs and the second region is used as scratchpad area for book
keeping modem execution stage details along with host system shared memory
region context details. The upper edge of the driver exposes the control and
data channels for user space application interaction. At lower edge these data
and control channels are associated to pipes. The pipes are lowest level
interfaces used over PCIe as a logical channel for message exchange. A single
channel maps to UL and DL pipe and are initialized on device open.

On UL path, driver copies application sent data to SKBs associate it with
transfer descriptor and puts it on to ring buffer for DMA transfer. Once
information has been updated in shared memory region, host gives a Doorbell
to modem to perform DMA and modem uses MSI to communicate back to host.
For receiving data in DL path, SKBs are pre-allocated during pipe open and
transfer descriptors are given to modem for DMA transfer.

The driver exposes two types of ports, namely "wwan0mbim0", a char device node
which is used for MBIM control operation and "wwan0-x",(x = 0,1,2..7) network
interfaces for IP data communication.
1) MBIM Control Interface:
This node exposes an interface between modem and application using char device
exposed by "IOSM" driver to establish and manage the MBIM data communication
with PCIe based Intel M.2 Modems.

2) MBIM Data Interface:
The IOSM driver exposes IP link interface "wwan0-x" of type "wwan" for IP traffic.
Iproute network utility is used for creating "wwan0-x" network interface and for
associating it with MBIM IP session. The Driver supports upto 8 IP sessions for
simultaneous IP communication.

This applies on top of WWAN core rtnetlink series posted here:
https://lore.kernel.org/netdev/1623486057-13075-1-git-send-email-loic.poulain@linaro.org/

Also driver has been compiled and tested on top of netdev net-next tree.
https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git/
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 97 insertions, 0 deletions

diff --git a/drivers/net/wwan/iosm/iosm_ipc_task_queue.h b/drivers/net/wwan/iosm/iosm_ipc_task_queue.h
new file mode 100644
index 000000000000..df6e9cd925a9
--- /dev/null
+++ b/drivers/net/wwan/iosm/iosm_ipc_task_queue.h
@@ -0,0 +1,97 @@
+/* SPDX-License-Identifier: GPL-2.0-only
+ *
+ * Copyright (C) 2020-21 Intel Corporation.
+ */
+
+#ifndef IOSM_IPC_TASK_QUEUE_H
+#define IOSM_IPC_TASK_QUEUE_H
+
+/* Number of available element for the input message queue of the IPC
+ * ipc_task
+ */
+#define IPC_THREAD_QUEUE_SIZE 256
+
+/**
+ * struct ipc_task_queue_args - Struct for Task queue elements
+ * @ipc_imem:   Pointer to struct iosm_imem
+ * @msg:        Message argument for tasklet function. (optional, can be NULL)
+ * @completion: OS object used to wait for the tasklet function to finish for
+ *              synchronous calls
+ * @func:       Function to be called in tasklet (tl) context
+ * @arg:        Generic integer argument for tasklet function (optional)
+ * @size:       Message size argument for tasklet function (optional)
+ * @response:   Return code of tasklet function for synchronous calls
+ * @is_copy:    Is true if msg contains a pointer to a copy of the original msg
+ *              for async. calls that needs to be freed once the tasklet returns
+ */
+struct ipc_task_queue_args {
+	struct iosm_imem *ipc_imem;
+	void *msg;
+	struct completion *completion;
+	int (*func)(struct iosm_imem *ipc_imem, int arg, void *msg,
+		    size_t size);
+	int arg;
+	size_t size;
+	int response;
+	u8 is_copy:1;
+};
+
+/**
+ * struct ipc_task_queue - Struct for Task queue
+ * @q_lock:     Protect the message queue of the ipc ipc_task
+ * @args:       Message queue of the IPC ipc_task
+ * @q_rpos:     First queue element to process.
+ * @q_wpos:     First free element of the input queue.
+ */
+struct ipc_task_queue {
+	spinlock_t q_lock; /* for atomic operation on queue */
+	struct ipc_task_queue_args args[IPC_THREAD_QUEUE_SIZE];
+	unsigned int q_rpos;
+	unsigned int q_wpos;
+};
+
+/**
+ * struct ipc_task - Struct for Task
+ * @dev:	 Pointer to device structure
+ * @ipc_tasklet: Tasklet for serialized work offload
+ *		 from interrupts and OS callbacks
+ * @ipc_queue:	 Task for entry into ipc task queue
+ */
+struct ipc_task {
+	struct device *dev;
+	struct tasklet_struct *ipc_tasklet;
+	struct ipc_task_queue ipc_queue;
+};
+
+/**
+ * ipc_task_init - Allocate a tasklet
+ * @ipc_task:	Pointer to ipc_task structure
+ * Returns: 0 on success and failure value on error.
+ */
+int ipc_task_init(struct ipc_task *ipc_task);
+
+/**
+ * ipc_task_deinit - Free a tasklet, invalidating its pointer.
+ * @ipc_task:	Pointer to ipc_task structure
+ */
+void ipc_task_deinit(struct ipc_task *ipc_task);
+
+/**
+ * ipc_task_queue_send_task - Synchronously/Asynchronously call a function in
+ *			      tasklet context.
+ * @imem:		Pointer to iosm_imem struct
+ * @func:		Function to be called in tasklet context
+ * @arg:		Integer argument for func
+ * @msg:		Message pointer argument for func
+ * @size:		Size argument for func
+ * @wait:		if true wait for result
+ *
+ * Returns: Result value returned by func or failure value if func could not
+ *	    be called.
+ */
+int ipc_task_queue_send_task(struct iosm_imem *imem,
+			     int (*func)(struct iosm_imem *ipc_imem, int arg,
+					 void *msg, size_t size),
+			     int arg, void *msg, size_t size, bool wait);
+
+#endif