2021-06-08 17:08:14

by M Chetan Kumar

[permalink] [raw]
Subject: [PATCH V4 08/16] net: iosm: bottom half

1) Bottom half(tasklet) for IRQ and task processing.
2) Tasks are processed asynchronous and synchronously.

Signed-off-by: M Chetan Kumar <[email protected]>
---
v4: no change.
v3: no change.
v2:
* Moved task queue struct to header file.
* Streamline multiple returns using goto.
---
drivers/net/wwan/iosm/iosm_ipc_task_queue.c | 202 ++++++++++++++++++++
drivers/net/wwan/iosm/iosm_ipc_task_queue.h | 97 ++++++++++
2 files changed, 299 insertions(+)
create mode 100644 drivers/net/wwan/iosm/iosm_ipc_task_queue.c
create mode 100644 drivers/net/wwan/iosm/iosm_ipc_task_queue.h

diff --git a/drivers/net/wwan/iosm/iosm_ipc_task_queue.c b/drivers/net/wwan/iosm/iosm_ipc_task_queue.c
new file mode 100644
index 000000000000..852a99166144
--- /dev/null
+++ b/drivers/net/wwan/iosm/iosm_ipc_task_queue.c
@@ -0,0 +1,202 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2020-21 Intel Corporation.
+ */
+
+#include "iosm_ipc_imem.h"
+#include "iosm_ipc_task_queue.h"
+
+/* Actual tasklet function, will be called whenever tasklet is scheduled.
+ * Calls event handler involves callback for each element in the message queue
+ */
+static void ipc_task_queue_handler(unsigned long data)
+{
+ struct ipc_task_queue *ipc_task = (struct ipc_task_queue *)data;
+ unsigned int q_rpos = ipc_task->q_rpos;
+
+ /* Loop over the input queue contents. */
+ while (q_rpos != ipc_task->q_wpos) {
+ /* Get the current first queue element. */
+ struct ipc_task_queue_args *args = &ipc_task->args[q_rpos];
+
+ /* Process the input message. */
+ if (args->func)
+ args->response = args->func(args->ipc_imem, args->arg,
+ args->msg, args->size);
+
+ /* Signal completion for synchronous calls */
+ if (args->completion)
+ complete(args->completion);
+
+ /* Free message if copy was allocated. */
+ if (args->is_copy)
+ kfree(args->msg);
+
+ /* Set invalid queue element. Technically
+ * spin_lock_irqsave is not required here as
+ * the array element has been processed already
+ * so we can assume that immediately after processing
+ * ipc_task element, queue will not rotate again to
+ * ipc_task same element within such short time.
+ */
+ args->completion = NULL;
+ args->func = NULL;
+ args->msg = NULL;
+ args->size = 0;
+ args->is_copy = false;
+
+ /* calculate the new read ptr and update the volatile read
+ * ptr
+ */
+ q_rpos = (q_rpos + 1) % IPC_THREAD_QUEUE_SIZE;
+ ipc_task->q_rpos = q_rpos;
+ }
+}
+
+/* Free memory alloc and trigger completions left in the queue during dealloc */
+static void ipc_task_queue_cleanup(struct ipc_task_queue *ipc_task)
+{
+ unsigned int q_rpos = ipc_task->q_rpos;
+
+ while (q_rpos != ipc_task->q_wpos) {
+ struct ipc_task_queue_args *args = &ipc_task->args[q_rpos];
+
+ if (args->completion)
+ complete(args->completion);
+
+ if (args->is_copy)
+ kfree(args->msg);
+
+ q_rpos = (q_rpos + 1) % IPC_THREAD_QUEUE_SIZE;
+ ipc_task->q_rpos = q_rpos;
+ }
+}
+
+/* Add a message to the queue and trigger the ipc_task. */
+static int
+ipc_task_queue_add_task(struct iosm_imem *ipc_imem,
+ int arg, void *msg,
+ int (*func)(struct iosm_imem *ipc_imem, int arg,
+ void *msg, size_t size),
+ size_t size, bool is_copy, bool wait)
+{
+ struct tasklet_struct *ipc_tasklet = ipc_imem->ipc_task->ipc_tasklet;
+ struct ipc_task_queue *ipc_task = &ipc_imem->ipc_task->ipc_queue;
+ struct completion completion;
+ unsigned int pos, nextpos;
+ unsigned long flags;
+ int result = -EIO;
+
+ init_completion(&completion);
+
+ /* tasklet send may be called from both interrupt or thread
+ * context, therefore protect queue operation by spinlock
+ */
+ spin_lock_irqsave(&ipc_task->q_lock, flags);
+
+ pos = ipc_task->q_wpos;
+ nextpos = (pos + 1) % IPC_THREAD_QUEUE_SIZE;
+
+ /* Get next queue position. */
+ if (nextpos != ipc_task->q_rpos) {
+ /* Get the reference to the queue element and save the passed
+ * values.
+ */
+ ipc_task->args[pos].arg = arg;
+ ipc_task->args[pos].msg = msg;
+ ipc_task->args[pos].func = func;
+ ipc_task->args[pos].ipc_imem = ipc_imem;
+ ipc_task->args[pos].size = size;
+ ipc_task->args[pos].is_copy = is_copy;
+ ipc_task->args[pos].completion = wait ? &completion : NULL;
+ ipc_task->args[pos].response = -1;
+
+ /* apply write barrier so that ipc_task->q_rpos elements
+ * are updated before ipc_task->q_wpos is being updated.
+ */
+ smp_wmb();
+
+ /* Update the status of the free queue space. */
+ ipc_task->q_wpos = nextpos;
+ result = 0;
+ }
+
+ spin_unlock_irqrestore(&ipc_task->q_lock, flags);
+
+ if (result == 0) {
+ tasklet_schedule(ipc_tasklet);
+
+ if (wait) {
+ wait_for_completion(&completion);
+ result = ipc_task->args[pos].response;
+ }
+ } else {
+ dev_err(ipc_imem->ipc_task->dev, "queue is full");
+ }
+
+ return result;
+}
+
+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)
+{
+ bool is_copy = false;
+ void *copy = msg;
+ int ret = -ENOMEM;
+
+ if (size > 0) {
+ copy = kmemdup(msg, size, GFP_ATOMIC);
+ if (!copy)
+ goto out;
+
+ is_copy = true;
+ }
+
+ ret = ipc_task_queue_add_task(imem, arg, copy, func,
+ size, is_copy, wait);
+ if (ret < 0) {
+ dev_err(imem->ipc_task->dev,
+ "add task failed for %ps %d, %p, %zu, %d", func, arg,
+ copy, size, is_copy);
+ if (is_copy)
+ kfree(copy);
+ goto out;
+ }
+
+ ret = 0;
+out:
+ return ret;
+}
+
+int ipc_task_init(struct ipc_task *ipc_task)
+{
+ struct ipc_task_queue *ipc_queue = &ipc_task->ipc_queue;
+
+ ipc_task->ipc_tasklet = kzalloc(sizeof(*ipc_task->ipc_tasklet),
+ GFP_KERNEL);
+
+ if (!ipc_task->ipc_tasklet)
+ return -ENOMEM;
+
+ /* Initialize the spinlock needed to protect the message queue of the
+ * ipc_task
+ */
+ spin_lock_init(&ipc_queue->q_lock);
+
+ tasklet_init(ipc_task->ipc_tasklet, ipc_task_queue_handler,
+ (unsigned long)ipc_queue);
+ return 0;
+}
+
+void ipc_task_deinit(struct ipc_task *ipc_task)
+{
+ tasklet_kill(ipc_task->ipc_tasklet);
+
+ kfree(ipc_task->ipc_tasklet);
+ /* This will free/complete any outstanding messages,
+ * without calling the actual handler
+ */
+ ipc_task_queue_cleanup(&ipc_task->ipc_queue);
+}
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
--
2.25.1