Overview of Linux kernel SPI support
====================================
-21-May-2007
+02-Feb-2012
What is SPI?
------------
and those methods.)
After you initialize the spi_master, then use spi_register_master() to
-publish it to the rest of the system. At that time, device nodes for
-the controller and any predeclared spi devices will be made available,
-and the driver model core will take care of binding them to drivers.
+publish it to the rest of the system. At that time, device nodes for the
+controller and any predeclared spi devices will be made available, and
+the driver model core will take care of binding them to drivers.
If you need to remove your SPI controller driver, spi_unregister_master()
will reverse the effect of spi_register_master().
** When you code setup(), ASSUME that the controller
** is actively processing transfers for another device.
- master->transfer(struct spi_device *spi, struct spi_message *message)
- This must not sleep. Its responsibility is arrange that the
- transfer happens and its complete() callback is issued. The two
- will normally happen later, after other transfers complete, and
- if the controller is idle it will need to be kickstarted.
-
master->cleanup(struct spi_device *spi)
Your controller driver may use spi_device.controller_state to hold
state it dynamically associates with that device. If you do that,
be sure to provide the cleanup() method to free that state.
+ master->prepare_transfer_hardware(struct spi_master *master)
+ This will be called by the queue mechanism to signal to the driver
+ that a message is coming in soon, so the subsystem requests the
+ driver to prepare the transfer hardware by issuing this call.
+ This may sleep.
+
+ master->unprepare_transfer_hardware(struct spi_master *master)
+ This will be called by the queue mechanism to signal to the driver
+ that there are no more messages pending in the queue and it may
+ relax the hardware (e.g. by power management calls). This may sleep.
+
+ master->transfer_one_message(struct spi_master *master,
+ struct spi_message *mesg)
+ The subsystem calls the driver to transfer a single message while
+ queuing transfers that arrive in the meantime. When the driver is
+ finished with this message, it must call
+ spi_finalize_current_message() so the subsystem can issue the next
+ transfer. This may sleep.
+
+ DEPRECATED METHODS
+
+ master->transfer(struct spi_device *spi, struct spi_message *message)
+ This must not sleep. Its responsibility is arrange that the
+ transfer happens and its complete() callback is issued. The two
+ will normally happen later, after other transfers complete, and
+ if the controller is idle it will need to be kickstarted. This
+ method is not used on queued controllers and must be NULL if
+ transfer_one_message() and (un)prepare_transfer_hardware() are
+ implemented.
+
SPI MESSAGE QUEUE
-The bulk of the driver will be managing the I/O queue fed by transfer().
+If you are happy with the standard queueing mechanism provided by the
+SPI subsystem, just implement the queued methods specified above. Using
+the message queue has the upside of centralizing a lot of code and
+providing pure process-context execution of methods. The message queue
+can also be elevated to realtime priority on high-priority SPI traffic.
+
+Unless the queueing mechanism in the SPI subsystem is selected, the bulk
+of the driver will be managing the I/O queue fed by the now deprecated
+function transfer().
That queue could be purely conceptual. For example, a driver used only
for low-frequency sensor access might be fine using synchronous PIO.
Mark Underwood
Andrew Victor
Vitaly Wool
-
+Grant Likely
+Mark Brown
+Linus Walleij
#include <linux/errno.h>
#include <linux/interrupt.h>
#include <linux/spi/spi.h>
-#include <linux/kthread.h>
#include <linux/delay.h>
#include <linux/clk.h>
#include <linux/err.h>
#include <linux/dma-mapping.h>
#include <linux/scatterlist.h>
#include <linux/pm_runtime.h>
-#include <linux/sched.h>
/*
* This macro is used to define some register default values.
struct clk *clk;
struct spi_master *master;
struct pl022_ssp_controller *master_info;
- /* Driver message pump */
- struct kthread_worker kworker;
- struct task_struct *kworker_task;
- struct kthread_work pump_messages;
- spinlock_t queue_lock;
- struct list_head queue;
- bool busy;
- bool running;
- /* Message transfer pump */
+ /* Message per-transfer pump */
struct tasklet_struct pump_transfers;
struct spi_message *cur_msg;
struct spi_transfer *cur_transfer;
struct sg_table sgt_rx;
struct sg_table sgt_tx;
char *dummypage;
+ bool dma_running;
#endif
};
static void giveback(struct pl022 *pl022)
{
struct spi_transfer *last_transfer;
- unsigned long flags;
- struct spi_message *msg;
pl022->next_msg_cs_active = false;
last_transfer = list_entry(pl022->cur_msg->transfers.prev,
* sent the current message could be unloaded, which
* could invalidate the cs_control() callback...
*/
-
/* get a pointer to the next message, if any */
- spin_lock_irqsave(&pl022->queue_lock, flags);
- if (list_empty(&pl022->queue))
- next_msg = NULL;
- else
- next_msg = list_entry(pl022->queue.next,
- struct spi_message, queue);
- spin_unlock_irqrestore(&pl022->queue_lock, flags);
+ next_msg = spi_get_next_queued_message(pl022->master);
/*
* see if the next and current messages point
pl022->cur_chip->cs_control(SSP_CHIP_DESELECT);
else
pl022->next_msg_cs_active = true;
+
}
- spin_lock_irqsave(&pl022->queue_lock, flags);
- msg = pl022->cur_msg;
pl022->cur_msg = NULL;
pl022->cur_transfer = NULL;
pl022->cur_chip = NULL;
- queue_kthread_work(&pl022->kworker, &pl022->pump_messages);
- spin_unlock_irqrestore(&pl022->queue_lock, flags);
-
- msg->state = NULL;
- if (msg->complete)
- msg->complete(msg->context);
+ spi_finalize_current_message(pl022->master);
}
/**
dmaengine_submit(txdesc);
dma_async_issue_pending(rxchan);
dma_async_issue_pending(txchan);
+ pl022->dma_running = true;
return 0;
dmaengine_terminate_all(rxchan);
dmaengine_terminate_all(txchan);
unmap_free_dma_scatter(pl022);
+ pl022->dma_running = false;
}
static void pl022_dma_remove(struct pl022 *pl022)
{
- if (pl022->busy)
+ if (pl022->dma_running)
terminate_dma(pl022);
if (pl022->dma_tx_channel)
dma_release_channel(pl022->dma_tx_channel);
return;
}
-/**
- * pump_messages - kthread work function which processes spi message queue
- * @work: pointer to kthread work struct contained in the pl022 private struct
- *
- * This function checks if there is any spi message in the queue that
- * needs processing and delegate control to appropriate function
- * do_polling_transfer()/do_interrupt_dma_transfer()
- * based on the kind of the transfer
- *
- */
-static void pump_messages(struct kthread_work *work)
+static int pl022_transfer_one_message(struct spi_master *master,
+ struct spi_message *msg)
{
- struct pl022 *pl022 =
- container_of(work, struct pl022, pump_messages);
- unsigned long flags;
- bool was_busy = false;
-
- /* Lock queue and check for queue work */
- spin_lock_irqsave(&pl022->queue_lock, flags);
- if (list_empty(&pl022->queue) || !pl022->running) {
- if (pl022->busy) {
- /* nothing more to do - disable spi/ssp and power off */
- writew((readw(SSP_CR1(pl022->virtbase)) &
- (~SSP_CR1_MASK_SSE)), SSP_CR1(pl022->virtbase));
-
- if (pl022->master_info->autosuspend_delay > 0) {
- pm_runtime_mark_last_busy(&pl022->adev->dev);
- pm_runtime_put_autosuspend(&pl022->adev->dev);
- } else {
- pm_runtime_put(&pl022->adev->dev);
- }
- }
- pl022->busy = false;
- spin_unlock_irqrestore(&pl022->queue_lock, flags);
- return;
- }
-
- /* Make sure we are not already running a message */
- if (pl022->cur_msg) {
- spin_unlock_irqrestore(&pl022->queue_lock, flags);
- return;
- }
- /* Extract head of queue */
- pl022->cur_msg =
- list_entry(pl022->queue.next, struct spi_message, queue);
-
- list_del_init(&pl022->cur_msg->queue);
- if (pl022->busy)
- was_busy = true;
- else
- pl022->busy = true;
- spin_unlock_irqrestore(&pl022->queue_lock, flags);
+ struct pl022 *pl022 = spi_master_get_devdata(master);
/* Initial message state */
- pl022->cur_msg->state = STATE_START;
- pl022->cur_transfer = list_entry(pl022->cur_msg->transfers.next,
- struct spi_transfer, transfer_list);
+ pl022->cur_msg = msg;
+ msg->state = STATE_START;
+
+ pl022->cur_transfer = list_entry(msg->transfers.next,
+ struct spi_transfer, transfer_list);
/* Setup the SPI using the per chip configuration */
- pl022->cur_chip = spi_get_ctldata(pl022->cur_msg->spi);
- if (!was_busy)
- /*
- * We enable the core voltage and clocks here, then the clocks
- * and core will be disabled when this thread is run again
- * and there is no more work to be done.
- */
- pm_runtime_get_sync(&pl022->adev->dev);
+ pl022->cur_chip = spi_get_ctldata(msg->spi);
restore_state(pl022);
flush(pl022);
do_polling_transfer(pl022);
else
do_interrupt_dma_transfer(pl022);
-}
-
-static int __init init_queue(struct pl022 *pl022)
-{
- struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 };
-
- INIT_LIST_HEAD(&pl022->queue);
- spin_lock_init(&pl022->queue_lock);
-
- pl022->running = false;
- pl022->busy = false;
-
- tasklet_init(&pl022->pump_transfers, pump_transfers,
- (unsigned long)pl022);
-
- init_kthread_worker(&pl022->kworker);
- pl022->kworker_task = kthread_run(kthread_worker_fn,
- &pl022->kworker,
- dev_name(pl022->master->dev.parent));
- if (IS_ERR(pl022->kworker_task)) {
- dev_err(&pl022->adev->dev,
- "failed to create message pump task\n");
- return -ENOMEM;
- }
- init_kthread_work(&pl022->pump_messages, pump_messages);
-
- /*
- * Board config will indicate if this controller should run the
- * message pump with high (realtime) priority to reduce the transfer
- * latency on the bus by minimising the delay between a transfer
- * request and the scheduling of the message pump thread. Without this
- * setting the message pump thread will remain at default priority.
- */
- if (pl022->master_info->rt) {
- dev_info(&pl022->adev->dev,
- "will run message pump with realtime priority\n");
- sched_setscheduler(pl022->kworker_task, SCHED_FIFO, ¶m);
- }
return 0;
}
-static int start_queue(struct pl022 *pl022)
+static int pl022_prepare_transfer_hardware(struct spi_master *master)
{
- unsigned long flags;
-
- spin_lock_irqsave(&pl022->queue_lock, flags);
-
- if (pl022->running || pl022->busy) {
- spin_unlock_irqrestore(&pl022->queue_lock, flags);
- return -EBUSY;
- }
-
- pl022->running = true;
- pl022->cur_msg = NULL;
- pl022->cur_transfer = NULL;
- pl022->cur_chip = NULL;
- pl022->next_msg_cs_active = false;
- spin_unlock_irqrestore(&pl022->queue_lock, flags);
-
- queue_kthread_work(&pl022->kworker, &pl022->pump_messages);
+ struct pl022 *pl022 = spi_master_get_devdata(master);
+ /*
+ * Just make sure we have all we need to run the transfer by syncing
+ * with the runtime PM framework.
+ */
+ pm_runtime_get_sync(&pl022->adev->dev);
return 0;
}
-static int stop_queue(struct pl022 *pl022)
+static int pl022_unprepare_transfer_hardware(struct spi_master *master)
{
- unsigned long flags;
- unsigned limit = 500;
- int status = 0;
+ struct pl022 *pl022 = spi_master_get_devdata(master);
- spin_lock_irqsave(&pl022->queue_lock, flags);
+ /* nothing more to do - disable spi/ssp and power off */
+ writew((readw(SSP_CR1(pl022->virtbase)) &
+ (~SSP_CR1_MASK_SSE)), SSP_CR1(pl022->virtbase));
- /* This is a bit lame, but is optimized for the common execution path.
- * A wait_queue on the pl022->busy could be used, but then the common
- * execution path (pump_messages) would be required to call wake_up or
- * friends on every SPI message. Do this instead */
- while ((!list_empty(&pl022->queue) || pl022->busy) && limit--) {
- spin_unlock_irqrestore(&pl022->queue_lock, flags);
- msleep(10);
- spin_lock_irqsave(&pl022->queue_lock, flags);
+ if (pl022->master_info->autosuspend_delay > 0) {
+ pm_runtime_mark_last_busy(&pl022->adev->dev);
+ pm_runtime_put_autosuspend(&pl022->adev->dev);
+ } else {
+ pm_runtime_put(&pl022->adev->dev);
}
- if (!list_empty(&pl022->queue) || pl022->busy)
- status = -EBUSY;
- else
- pl022->running = false;
-
- spin_unlock_irqrestore(&pl022->queue_lock, flags);
-
- return status;
-}
-
-static int destroy_queue(struct pl022 *pl022)
-{
- int status;
-
- status = stop_queue(pl022);
-
- /*
- * We are unloading the module or failing to load (only two calls
- * to this routine), and neither call can handle a return value.
- * However, flush_kthread_worker will block until all work is done.
- * If the reason that stop_queue timed out is that the work will never
- * finish, then it does no good to call flush/stop thread, so
- * return anyway.
- */
- if (status != 0)
- return status;
-
- flush_kthread_worker(&pl022->kworker);
- kthread_stop(pl022->kworker_task);
-
return 0;
}
return 0;
}
-/**
- * pl022_transfer - transfer function registered to SPI master framework
- * @spi: spi device which is requesting transfer
- * @msg: spi message which is to handled is queued to driver queue
- *
- * This function is registered to the SPI framework for this SPI master
- * controller. It will queue the spi_message in the queue of driver if
- * the queue is not stopped and return.
- */
-static int pl022_transfer(struct spi_device *spi, struct spi_message *msg)
-{
- struct pl022 *pl022 = spi_master_get_devdata(spi->master);
- unsigned long flags;
-
- spin_lock_irqsave(&pl022->queue_lock, flags);
-
- if (!pl022->running) {
- spin_unlock_irqrestore(&pl022->queue_lock, flags);
- return -ESHUTDOWN;
- }
- msg->actual_length = 0;
- msg->status = -EINPROGRESS;
- msg->state = STATE_START;
-
- list_add_tail(&msg->queue, &pl022->queue);
- if (pl022->running && !pl022->busy)
- queue_kthread_work(&pl022->kworker, &pl022->pump_messages);
-
- spin_unlock_irqrestore(&pl022->queue_lock, flags);
- return 0;
-}
-
static inline u32 spi_rate(u32 rate, u16 cpsdvsr, u16 scr)
{
return rate / (cpsdvsr * (1 + scr));
master->num_chipselect = platform_info->num_chipselect;
master->cleanup = pl022_cleanup;
master->setup = pl022_setup;
- master->transfer = pl022_transfer;
+ master->prepare_transfer_hardware = pl022_prepare_transfer_hardware;
+ master->transfer_one_message = pl022_transfer_one_message;
+ master->unprepare_transfer_hardware = pl022_unprepare_transfer_hardware;
+ master->rt = platform_info->rt;
/*
* Supports mode 0-3, loopback, and active low CS. Transfers are
goto err_no_clk_en;
}
+ /* Initialize transfer pump */
+ tasklet_init(&pl022->pump_transfers, pump_transfers,
+ (unsigned long)pl022);
+
/* Disable SSP */
writew((readw(SSP_CR1(pl022->virtbase)) & (~SSP_CR1_MASK_SSE)),
SSP_CR1(pl022->virtbase));
platform_info->enable_dma = 0;
}
- /* Initialize and start queue */
- status = init_queue(pl022);
- if (status != 0) {
- dev_err(&adev->dev, "probe - problem initializing queue\n");
- goto err_init_queue;
- }
- status = start_queue(pl022);
- if (status != 0) {
- dev_err(&adev->dev, "probe - problem starting queue\n");
- goto err_start_queue;
- }
/* Register with the SPI framework */
amba_set_drvdata(adev, pl022);
status = spi_register_master(master);
return 0;
err_spi_register:
- err_start_queue:
- err_init_queue:
- destroy_queue(pl022);
if (platform_info->enable_dma)
pl022_dma_remove(pl022);
*/
pm_runtime_get_noresume(&adev->dev);
- /* Remove the queue */
- if (destroy_queue(pl022) != 0)
- dev_err(&adev->dev, "queue remove failed\n");
load_ssp_default_config(pl022);
if (pl022->master_info->enable_dma)
pl022_dma_remove(pl022);
static int pl022_suspend(struct device *dev)
{
struct pl022 *pl022 = dev_get_drvdata(dev);
- int status = 0;
+ int ret;
- status = stop_queue(pl022);
- if (status) {
- dev_warn(dev, "suspend cannot stop queue\n");
- return status;
+ ret = spi_master_suspend(pl022->master);
+ if (ret) {
+ dev_warn(dev, "cannot suspend master\n");
+ return ret;
}
dev_dbg(dev, "suspended\n");
static int pl022_resume(struct device *dev)
{
struct pl022 *pl022 = dev_get_drvdata(dev);
- int status = 0;
+ int ret;
/* Start the queue running */
- status = start_queue(pl022);
- if (status)
- dev_err(dev, "problem starting queue (%d)\n", status);
+ ret = spi_master_resume(pl022->master);
+ if (ret)
+ dev_err(dev, "problem starting queue (%d)\n", ret);
else
dev_dbg(dev, "resumed\n");
- return status;
+ return ret;
}
#endif /* CONFIG_PM */
#include <linux/of_spi.h>
#include <linux/pm_runtime.h>
#include <linux/export.h>
+#include <linux/sched.h>
+#include <linux/delay.h>
+#include <linux/kthread.h>
static void spidev_release(struct device *dev)
{
/*-------------------------------------------------------------------------*/
+/**
+ * spi_pump_messages - kthread work function which processes spi message queue
+ * @work: pointer to kthread work struct contained in the master struct
+ *
+ * This function checks if there is any spi message in the queue that
+ * needs processing and if so call out to the driver to initialize hardware
+ * and transfer each message.
+ *
+ */
+static void spi_pump_messages(struct kthread_work *work)
+{
+ struct spi_master *master =
+ container_of(work, struct spi_master, pump_messages);
+ unsigned long flags;
+ bool was_busy = false;
+ int ret;
+
+ /* Lock queue and check for queue work */
+ spin_lock_irqsave(&master->queue_lock, flags);
+ if (list_empty(&master->queue) || !master->running) {
+ if (master->busy) {
+ ret = master->unprepare_transfer_hardware(master);
+ if (ret) {
+ dev_err(&master->dev,
+ "failed to unprepare transfer hardware\n");
+ return;
+ }
+ }
+ master->busy = false;
+ spin_unlock_irqrestore(&master->queue_lock, flags);
+ return;
+ }
+
+ /* Make sure we are not already running a message */
+ if (master->cur_msg) {
+ spin_unlock_irqrestore(&master->queue_lock, flags);
+ return;
+ }
+ /* Extract head of queue */
+ master->cur_msg =
+ list_entry(master->queue.next, struct spi_message, queue);
+
+ list_del_init(&master->cur_msg->queue);
+ if (master->busy)
+ was_busy = true;
+ else
+ master->busy = true;
+ spin_unlock_irqrestore(&master->queue_lock, flags);
+
+ if (!was_busy) {
+ ret = master->prepare_transfer_hardware(master);
+ if (ret) {
+ dev_err(&master->dev,
+ "failed to prepare transfer hardware\n");
+ return;
+ }
+ }
+
+ ret = master->transfer_one_message(master, master->cur_msg);
+ if (ret) {
+ dev_err(&master->dev,
+ "failed to transfer one message from queue\n");
+ return;
+ }
+}
+
+static int spi_init_queue(struct spi_master *master)
+{
+ struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 };
+
+ INIT_LIST_HEAD(&master->queue);
+ spin_lock_init(&master->queue_lock);
+
+ master->running = false;
+ master->busy = false;
+
+ init_kthread_worker(&master->kworker);
+ master->kworker_task = kthread_run(kthread_worker_fn,
+ &master->kworker,
+ dev_name(&master->dev));
+ if (IS_ERR(master->kworker_task)) {
+ dev_err(&master->dev, "failed to create message pump task\n");
+ return -ENOMEM;
+ }
+ init_kthread_work(&master->pump_messages, spi_pump_messages);
+
+ /*
+ * Master config will indicate if this controller should run the
+ * message pump with high (realtime) priority to reduce the transfer
+ * latency on the bus by minimising the delay between a transfer
+ * request and the scheduling of the message pump thread. Without this
+ * setting the message pump thread will remain at default priority.
+ */
+ if (master->rt) {
+ dev_info(&master->dev,
+ "will run message pump with realtime priority\n");
+ sched_setscheduler(master->kworker_task, SCHED_FIFO, ¶m);
+ }
+
+ return 0;
+}
+
+/**
+ * spi_get_next_queued_message() - called by driver to check for queued
+ * messages
+ * @master: the master to check for queued messages
+ *
+ * If there are more messages in the queue, the next message is returned from
+ * this call.
+ */
+struct spi_message *spi_get_next_queued_message(struct spi_master *master)
+{
+ struct spi_message *next;
+ unsigned long flags;
+
+ /* get a pointer to the next message, if any */
+ spin_lock_irqsave(&master->queue_lock, flags);
+ if (list_empty(&master->queue))
+ next = NULL;
+ else
+ next = list_entry(master->queue.next,
+ struct spi_message, queue);
+ spin_unlock_irqrestore(&master->queue_lock, flags);
+
+ return next;
+}
+EXPORT_SYMBOL_GPL(spi_get_next_queued_message);
+
+/**
+ * spi_finalize_current_message() - the current message is complete
+ * @master: the master to return the message to
+ *
+ * Called by the driver to notify the core that the message in the front of the
+ * queue is complete and can be removed from the queue.
+ */
+void spi_finalize_current_message(struct spi_master *master)
+{
+ struct spi_message *mesg;
+ unsigned long flags;
+
+ spin_lock_irqsave(&master->queue_lock, flags);
+ mesg = master->cur_msg;
+ master->cur_msg = NULL;
+
+ queue_kthread_work(&master->kworker, &master->pump_messages);
+ spin_unlock_irqrestore(&master->queue_lock, flags);
+
+ mesg->state = NULL;
+ if (mesg->complete)
+ mesg->complete(mesg->context);
+}
+EXPORT_SYMBOL_GPL(spi_finalize_current_message);
+
+static int spi_start_queue(struct spi_master *master)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&master->queue_lock, flags);
+
+ if (master->running || master->busy) {
+ spin_unlock_irqrestore(&master->queue_lock, flags);
+ return -EBUSY;
+ }
+
+ master->running = true;
+ master->cur_msg = NULL;
+ spin_unlock_irqrestore(&master->queue_lock, flags);
+
+ queue_kthread_work(&master->kworker, &master->pump_messages);
+
+ return 0;
+}
+
+static int spi_stop_queue(struct spi_master *master)
+{
+ unsigned long flags;
+ unsigned limit = 500;
+ int ret = 0;
+
+ spin_lock_irqsave(&master->queue_lock, flags);
+
+ /*
+ * This is a bit lame, but is optimized for the common execution path.
+ * A wait_queue on the master->busy could be used, but then the common
+ * execution path (pump_messages) would be required to call wake_up or
+ * friends on every SPI message. Do this instead.
+ */
+ while ((!list_empty(&master->queue) || master->busy) && limit--) {
+ spin_unlock_irqrestore(&master->queue_lock, flags);
+ msleep(10);
+ spin_lock_irqsave(&master->queue_lock, flags);
+ }
+
+ if (!list_empty(&master->queue) || master->busy)
+ ret = -EBUSY;
+ else
+ master->running = false;
+
+ spin_unlock_irqrestore(&master->queue_lock, flags);
+
+ if (ret) {
+ dev_warn(&master->dev,
+ "could not stop message queue\n");
+ return ret;
+ }
+ return ret;
+}
+
+static int spi_destroy_queue(struct spi_master *master)
+{
+ int ret;
+
+ ret = spi_stop_queue(master);
+
+ /*
+ * flush_kthread_worker will block until all work is done.
+ * If the reason that stop_queue timed out is that the work will never
+ * finish, then it does no good to call flush/stop thread, so
+ * return anyway.
+ */
+ if (ret) {
+ dev_err(&master->dev, "problem destroying queue\n");
+ return ret;
+ }
+
+ flush_kthread_worker(&master->kworker);
+ kthread_stop(master->kworker_task);
+
+ return 0;
+}
+
+/**
+ * spi_queued_transfer - transfer function for queued transfers
+ * @spi: spi device which is requesting transfer
+ * @msg: spi message which is to handled is queued to driver queue
+ */
+static int spi_queued_transfer(struct spi_device *spi, struct spi_message *msg)
+{
+ struct spi_master *master = spi->master;
+ unsigned long flags;
+
+ spin_lock_irqsave(&master->queue_lock, flags);
+
+ if (!master->running) {
+ spin_unlock_irqrestore(&master->queue_lock, flags);
+ return -ESHUTDOWN;
+ }
+ msg->actual_length = 0;
+ msg->status = -EINPROGRESS;
+
+ list_add_tail(&msg->queue, &master->queue);
+ if (master->running && !master->busy)
+ queue_kthread_work(&master->kworker, &master->pump_messages);
+
+ spin_unlock_irqrestore(&master->queue_lock, flags);
+ return 0;
+}
+
+static int spi_master_initialize_queue(struct spi_master *master)
+{
+ int ret;
+
+ master->queued = true;
+ master->transfer = spi_queued_transfer;
+
+ /* Initialize and start queue */
+ ret = spi_init_queue(master);
+ if (ret) {
+ dev_err(&master->dev, "problem initializing queue\n");
+ goto err_init_queue;
+ }
+ ret = spi_start_queue(master);
+ if (ret) {
+ dev_err(&master->dev, "problem starting queue\n");
+ goto err_start_queue;
+ }
+
+ return 0;
+
+err_start_queue:
+err_init_queue:
+ spi_destroy_queue(master);
+ return ret;
+}
+
+/*-------------------------------------------------------------------------*/
+
static void spi_master_release(struct device *dev)
{
struct spi_master *master;
};
+
/**
* spi_alloc_master - allocate SPI master controller
* @dev: the controller, possibly using the platform_bus
dev_dbg(dev, "registered master %s%s\n", dev_name(&master->dev),
dynamic ? " (dynamic)" : "");
+ /* If we're using a queued driver, start the queue */
+ if (master->transfer)
+ dev_info(dev, "master is unqueued, this is deprecated\n");
+ else {
+ status = spi_master_initialize_queue(master);
+ if (status) {
+ device_unregister(&master->dev);
+ goto done;
+ }
+ }
+
mutex_lock(&board_lock);
list_add_tail(&master->list, &spi_master_list);
list_for_each_entry(bi, &board_list, list)
}
EXPORT_SYMBOL_GPL(spi_register_master);
-
static int __unregister(struct device *dev, void *null)
{
spi_unregister_device(to_spi_device(dev));
{
int dummy;
+ if (master->queued) {
+ if (spi_destroy_queue(master))
+ dev_err(&master->dev, "queue remove failed\n");
+ }
+
mutex_lock(&board_lock);
list_del(&master->list);
mutex_unlock(&board_lock);
}
EXPORT_SYMBOL_GPL(spi_unregister_master);
+int spi_master_suspend(struct spi_master *master)
+{
+ int ret;
+
+ /* Basically no-ops for non-queued masters */
+ if (!master->queued)
+ return 0;
+
+ ret = spi_stop_queue(master);
+ if (ret)
+ dev_err(&master->dev, "queue stop failed\n");
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(spi_master_suspend);
+
+int spi_master_resume(struct spi_master *master)
+{
+ int ret;
+
+ if (!master->queued)
+ return 0;
+
+ ret = spi_start_queue(master);
+ if (ret)
+ dev_err(&master->dev, "queue restart failed\n");
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(spi_master_resume);
+
static int __spi_master_match(struct device *dev, void *data)
{
struct spi_master *m;
#include <linux/device.h>
#include <linux/mod_devicetable.h>
#include <linux/slab.h>
+#include <linux/kthread.h>
/*
* INTERFACES between SPI master-side drivers and SPI infrastructure.
* the device whose settings are being modified.
* @transfer: adds a message to the controller's transfer queue.
* @cleanup: frees controller-specific state
+ * @queued: whether this master is providing an internal message queue
+ * @kworker: thread struct for message pump
+ * @kworker_task: pointer to task for message pump kworker thread
+ * @pump_messages: work struct for scheduling work to the message pump
+ * @queue_lock: spinlock to syncronise access to message queue
+ * @queue: message queue
+ * @cur_msg: the currently in-flight message
+ * @busy: message pump is busy
+ * @running: message pump is running
+ * @rt: whether this queue is set to run as a realtime task
+ * @prepare_transfer_hardware: a message will soon arrive from the queue
+ * so the subsystem requests the driver to prepare the transfer hardware
+ * by issuing this call
+ * @transfer_one_message: the subsystem calls the driver to transfer a single
+ * message while queuing transfers that arrive in the meantime. When the
+ * driver is finished with this message, it must call
+ * spi_finalize_current_message() so the subsystem can issue the next
+ * transfer
+ * @prepare_transfer_hardware: there are currently no more messages on the
+ * queue so the subsystem notifies the driver that it may relax the
+ * hardware by issuing this call
*
* Each SPI master controller can communicate with one or more @spi_device
* children. These make a small bus, sharing MOSI, MISO and SCK signals
/* called on release() to free memory provided by spi_master */
void (*cleanup)(struct spi_device *spi);
+
+ /*
+ * These hooks are for drivers that want to use the generic
+ * master transfer queueing mechanism. If these are used, the
+ * transfer() function above must NOT be specified by the driver.
+ * Over time we expect SPI drivers to be phased over to this API.
+ */
+ bool queued;
+ struct kthread_worker kworker;
+ struct task_struct *kworker_task;
+ struct kthread_work pump_messages;
+ spinlock_t queue_lock;
+ struct list_head queue;
+ struct spi_message *cur_msg;
+ bool busy;
+ bool running;
+ bool rt;
+
+ int (*prepare_transfer_hardware)(struct spi_master *master);
+ int (*transfer_one_message)(struct spi_master *master,
+ struct spi_message *mesg);
+ int (*unprepare_transfer_hardware)(struct spi_master *master);
};
static inline void *spi_master_get_devdata(struct spi_master *master)
put_device(&master->dev);
}
+/* PM calls that need to be issued by the driver */
+extern int spi_master_suspend(struct spi_master *master);
+extern int spi_master_resume(struct spi_master *master);
+
+/* Calls the driver make to interact with the message queue */
+extern struct spi_message *spi_get_next_queued_message(struct spi_master *master);
+extern void spi_finalize_current_message(struct spi_master *master);
/* the spi driver core manages memory for the spi_master classdev */
extern struct spi_master *
projects / karo-tx-linux.git / commitdiff