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-rw-r--r--target/linux/generic/patches-2.6.33/910-backport-spi-bus-locking-api.patch382
1 files changed, 0 insertions, 382 deletions
diff --git a/target/linux/generic/patches-2.6.33/910-backport-spi-bus-locking-api.patch b/target/linux/generic/patches-2.6.33/910-backport-spi-bus-locking-api.patch
deleted file mode 100644
index 23becab917..0000000000
--- a/target/linux/generic/patches-2.6.33/910-backport-spi-bus-locking-api.patch
+++ /dev/null
@@ -1,382 +0,0 @@
-From cf32b71e981ca63e8f349d8585ca2a3583b556e0 Mon Sep 17 00:00:00 2001
-From: Ernst Schwab <eschwab@online.de>
-Date: Mon, 28 Jun 2010 17:49:29 -0700
-Subject: [PATCH] spi/mmc_spi: SPI bus locking API, using mutex
-
-SPI bus locking API to allow exclusive access to the SPI bus, especially, but
-not limited to, for the mmc_spi driver.
-
-Coded according to an outline from Grant Likely; here is his
-specification (accidentally swapped function names corrected):
-
-It requires 3 things to be added to struct spi_master.
-- 1 Mutex
-- 1 spin lock
-- 1 flag.
-
-The mutex protects spi_sync, and provides sleeping "for free"
-The spinlock protects the atomic spi_async call.
-The flag is set when the lock is obtained, and checked while holding
-the spinlock in spi_async(). If the flag is checked, then spi_async()
-must fail immediately.
-
-The current runtime API looks like this:
-spi_async(struct spi_device*, struct spi_message*);
-spi_sync(struct spi_device*, struct spi_message*);
-
-The API needs to be extended to this:
-spi_async(struct spi_device*, struct spi_message*)
-spi_sync(struct spi_device*, struct spi_message*)
-spi_bus_lock(struct spi_master*) /* although struct spi_device* might
-be easier */
-spi_bus_unlock(struct spi_master*)
-spi_async_locked(struct spi_device*, struct spi_message*)
-spi_sync_locked(struct spi_device*, struct spi_message*)
-
-Drivers can only call the last two if they already hold the spi_master_lock().
-
-spi_bus_lock() obtains the mutex, obtains the spin lock, sets the
-flag, and releases the spin lock before returning. It doesn't even
-need to sleep while waiting for "in-flight" spi_transactions to
-complete because its purpose is to guarantee no additional
-transactions are added. It does not guarantee that the bus is idle.
-
-spi_bus_unlock() clears the flag and releases the mutex, which will
-wake up any waiters.
-
-The difference between spi_async() and spi_async_locked() is that the
-locked version bypasses the check of the lock flag. Both versions
-need to obtain the spinlock.
-
-The difference between spi_sync() and spi_sync_locked() is that
-spi_sync() must hold the mutex while enqueuing a new transfer.
-spi_sync_locked() doesn't because the mutex is already held. Note
-however that spi_sync must *not* continue to hold the mutex while
-waiting for the transfer to complete, otherwise only one transfer
-could be queued up at a time!
-
-Almost no code needs to be written. The current spi_async() and
-spi_sync() can probably be renamed to __spi_async() and __spi_sync()
-so that spi_async(), spi_sync(), spi_async_locked() and
-spi_sync_locked() can just become wrappers around the common code.
-
-spi_sync() is protected by a mutex because it can sleep
-spi_async() needs to be protected with a flag and a spinlock because
-it can be called atomically and must not sleep
-
-Signed-off-by: Ernst Schwab <eschwab@online.de>
-[grant.likely@secretlab.ca: use spin_lock_irqsave()]
-Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
-Tested-by: Matt Fleming <matt@console-pimps.org>
-Tested-by: Antonio Ospite <ospite@studenti.unina.it>
----
- drivers/spi/spi.c | 225 ++++++++++++++++++++++++++++++++++++++++-------
- include/linux/spi/spi.h | 12 +++
- 2 files changed, 204 insertions(+), 33 deletions(-)
-
---- a/drivers/spi/spi.c
-+++ b/drivers/spi/spi.c
-@@ -524,6 +524,10 @@ int spi_register_master(struct spi_maste
- dynamic = 1;
- }
-
-+ spin_lock_init(&master->bus_lock_spinlock);
-+ mutex_init(&master->bus_lock_mutex);
-+ master->bus_lock_flag = 0;
-+
- /* register the device, then userspace will see it.
- * registration fails if the bus ID is in use.
- */
-@@ -663,6 +667,35 @@ int spi_setup(struct spi_device *spi)
- }
- EXPORT_SYMBOL_GPL(spi_setup);
-
-+static int __spi_async(struct spi_device *spi, struct spi_message *message)
-+{
-+ struct spi_master *master = spi->master;
-+
-+ /* Half-duplex links include original MicroWire, and ones with
-+ * only one data pin like SPI_3WIRE (switches direction) or where
-+ * either MOSI or MISO is missing. They can also be caused by
-+ * software limitations.
-+ */
-+ if ((master->flags & SPI_MASTER_HALF_DUPLEX)
-+ || (spi->mode & SPI_3WIRE)) {
-+ struct spi_transfer *xfer;
-+ unsigned flags = master->flags;
-+
-+ list_for_each_entry(xfer, &message->transfers, transfer_list) {
-+ if (xfer->rx_buf && xfer->tx_buf)
-+ return -EINVAL;
-+ if ((flags & SPI_MASTER_NO_TX) && xfer->tx_buf)
-+ return -EINVAL;
-+ if ((flags & SPI_MASTER_NO_RX) && xfer->rx_buf)
-+ return -EINVAL;
-+ }
-+ }
-+
-+ message->spi = spi;
-+ message->status = -EINPROGRESS;
-+ return master->transfer(spi, message);
-+}
-+
- /**
- * spi_async - asynchronous SPI transfer
- * @spi: device with which data will be exchanged
-@@ -695,33 +728,68 @@ EXPORT_SYMBOL_GPL(spi_setup);
- int spi_async(struct spi_device *spi, struct spi_message *message)
- {
- struct spi_master *master = spi->master;
-+ int ret;
-+ unsigned long flags;
-
-- /* Half-duplex links include original MicroWire, and ones with
-- * only one data pin like SPI_3WIRE (switches direction) or where
-- * either MOSI or MISO is missing. They can also be caused by
-- * software limitations.
-- */
-- if ((master->flags & SPI_MASTER_HALF_DUPLEX)
-- || (spi->mode & SPI_3WIRE)) {
-- struct spi_transfer *xfer;
-- unsigned flags = master->flags;
-+ spin_lock_irqsave(&master->bus_lock_spinlock, flags);
-
-- list_for_each_entry(xfer, &message->transfers, transfer_list) {
-- if (xfer->rx_buf && xfer->tx_buf)
-- return -EINVAL;
-- if ((flags & SPI_MASTER_NO_TX) && xfer->tx_buf)
-- return -EINVAL;
-- if ((flags & SPI_MASTER_NO_RX) && xfer->rx_buf)
-- return -EINVAL;
-- }
-- }
-+ if (master->bus_lock_flag)
-+ ret = -EBUSY;
-+ else
-+ ret = __spi_async(spi, message);
-
-- message->spi = spi;
-- message->status = -EINPROGRESS;
-- return master->transfer(spi, message);
-+ spin_unlock_irqrestore(&master->bus_lock_spinlock, flags);
-+
-+ return ret;
- }
- EXPORT_SYMBOL_GPL(spi_async);
-
-+/**
-+ * spi_async_locked - version of spi_async with exclusive bus usage
-+ * @spi: device with which data will be exchanged
-+ * @message: describes the data transfers, including completion callback
-+ * Context: any (irqs may be blocked, etc)
-+ *
-+ * This call may be used in_irq and other contexts which can't sleep,
-+ * as well as from task contexts which can sleep.
-+ *
-+ * The completion callback is invoked in a context which can't sleep.
-+ * Before that invocation, the value of message->status is undefined.
-+ * When the callback is issued, message->status holds either zero (to
-+ * indicate complete success) or a negative error code. After that
-+ * callback returns, the driver which issued the transfer request may
-+ * deallocate the associated memory; it's no longer in use by any SPI
-+ * core or controller driver code.
-+ *
-+ * Note that although all messages to a spi_device are handled in
-+ * FIFO order, messages may go to different devices in other orders.
-+ * Some device might be higher priority, or have various "hard" access
-+ * time requirements, for example.
-+ *
-+ * On detection of any fault during the transfer, processing of
-+ * the entire message is aborted, and the device is deselected.
-+ * Until returning from the associated message completion callback,
-+ * no other spi_message queued to that device will be processed.
-+ * (This rule applies equally to all the synchronous transfer calls,
-+ * which are wrappers around this core asynchronous primitive.)
-+ */
-+int spi_async_locked(struct spi_device *spi, struct spi_message *message)
-+{
-+ struct spi_master *master = spi->master;
-+ int ret;
-+ unsigned long flags;
-+
-+ spin_lock_irqsave(&master->bus_lock_spinlock, flags);
-+
-+ ret = __spi_async(spi, message);
-+
-+ spin_unlock_irqrestore(&master->bus_lock_spinlock, flags);
-+
-+ return ret;
-+
-+}
-+EXPORT_SYMBOL_GPL(spi_async_locked);
-+
-
- /*-------------------------------------------------------------------------*/
-
-@@ -735,6 +803,32 @@ static void spi_complete(void *arg)
- complete(arg);
- }
-
-+static int __spi_sync(struct spi_device *spi, struct spi_message *message,
-+ int bus_locked)
-+{
-+ DECLARE_COMPLETION_ONSTACK(done);
-+ int status;
-+ struct spi_master *master = spi->master;
-+
-+ message->complete = spi_complete;
-+ message->context = &done;
-+
-+ if (!bus_locked)
-+ mutex_lock(&master->bus_lock_mutex);
-+
-+ status = spi_async_locked(spi, message);
-+
-+ if (!bus_locked)
-+ mutex_unlock(&master->bus_lock_mutex);
-+
-+ if (status == 0) {
-+ wait_for_completion(&done);
-+ status = message->status;
-+ }
-+ message->context = NULL;
-+ return status;
-+}
-+
- /**
- * spi_sync - blocking/synchronous SPI data transfers
- * @spi: device with which data will be exchanged
-@@ -758,21 +852,86 @@ static void spi_complete(void *arg)
- */
- int spi_sync(struct spi_device *spi, struct spi_message *message)
- {
-- DECLARE_COMPLETION_ONSTACK(done);
-- int status;
--
-- message->complete = spi_complete;
-- message->context = &done;
-- status = spi_async(spi, message);
-- if (status == 0) {
-- wait_for_completion(&done);
-- status = message->status;
-- }
-- message->context = NULL;
-- return status;
-+ return __spi_sync(spi, message, 0);
- }
- EXPORT_SYMBOL_GPL(spi_sync);
-
-+/**
-+ * spi_sync_locked - version of spi_sync with exclusive bus usage
-+ * @spi: device with which data will be exchanged
-+ * @message: describes the data transfers
-+ * Context: can sleep
-+ *
-+ * This call may only be used from a context that may sleep. The sleep
-+ * is non-interruptible, and has no timeout. Low-overhead controller
-+ * drivers may DMA directly into and out of the message buffers.
-+ *
-+ * This call should be used by drivers that require exclusive access to the
-+ * SPI bus. It has to be preceeded by a spi_bus_lock call. The SPI bus must
-+ * be released by a spi_bus_unlock call when the exclusive access is over.
-+ *
-+ * It returns zero on success, else a negative error code.
-+ */
-+int spi_sync_locked(struct spi_device *spi, struct spi_message *message)
-+{
-+ return __spi_sync(spi, message, 1);
-+}
-+EXPORT_SYMBOL_GPL(spi_sync_locked);
-+
-+/**
-+ * spi_bus_lock - obtain a lock for exclusive SPI bus usage
-+ * @master: SPI bus master that should be locked for exclusive bus access
-+ * Context: can sleep
-+ *
-+ * This call may only be used from a context that may sleep. The sleep
-+ * is non-interruptible, and has no timeout.
-+ *
-+ * This call should be used by drivers that require exclusive access to the
-+ * SPI bus. The SPI bus must be released by a spi_bus_unlock call when the
-+ * exclusive access is over. Data transfer must be done by spi_sync_locked
-+ * and spi_async_locked calls when the SPI bus lock is held.
-+ *
-+ * It returns zero on success, else a negative error code.
-+ */
-+int spi_bus_lock(struct spi_master *master)
-+{
-+ unsigned long flags;
-+
-+ mutex_lock(&master->bus_lock_mutex);
-+
-+ spin_lock_irqsave(&master->bus_lock_spinlock, flags);
-+ master->bus_lock_flag = 1;
-+ spin_unlock_irqrestore(&master->bus_lock_spinlock, flags);
-+
-+ /* mutex remains locked until spi_bus_unlock is called */
-+
-+ return 0;
-+}
-+EXPORT_SYMBOL_GPL(spi_bus_lock);
-+
-+/**
-+ * spi_bus_unlock - release the lock for exclusive SPI bus usage
-+ * @master: SPI bus master that was locked for exclusive bus access
-+ * Context: can sleep
-+ *
-+ * This call may only be used from a context that may sleep. The sleep
-+ * is non-interruptible, and has no timeout.
-+ *
-+ * This call releases an SPI bus lock previously obtained by an spi_bus_lock
-+ * call.
-+ *
-+ * It returns zero on success, else a negative error code.
-+ */
-+int spi_bus_unlock(struct spi_master *master)
-+{
-+ master->bus_lock_flag = 0;
-+
-+ mutex_unlock(&master->bus_lock_mutex);
-+
-+ return 0;
-+}
-+EXPORT_SYMBOL_GPL(spi_bus_unlock);
-+
- /* portable code must never pass more than 32 bytes */
- #define SPI_BUFSIZ max(32,SMP_CACHE_BYTES)
-
---- a/include/linux/spi/spi.h
-+++ b/include/linux/spi/spi.h
-@@ -261,6 +261,13 @@ struct spi_master {
- #define SPI_MASTER_NO_RX BIT(1) /* can't do buffer read */
- #define SPI_MASTER_NO_TX BIT(2) /* can't do buffer write */
-
-+ /* lock and mutex for SPI bus locking */
-+ spinlock_t bus_lock_spinlock;
-+ struct mutex bus_lock_mutex;
-+
-+ /* flag indicating that the SPI bus is locked for exclusive use */
-+ bool bus_lock_flag;
-+
- /* Setup mode and clock, etc (spi driver may call many times).
- *
- * IMPORTANT: this may be called when transfers to another
-@@ -541,6 +548,8 @@ static inline void spi_message_free(stru
-
- extern int spi_setup(struct spi_device *spi);
- extern int spi_async(struct spi_device *spi, struct spi_message *message);
-+extern int spi_async_locked(struct spi_device *spi,
-+ struct spi_message *message);
-
- /*---------------------------------------------------------------------------*/
-
-@@ -550,6 +559,9 @@ extern int spi_async(struct spi_device *
- */
-
- extern int spi_sync(struct spi_device *spi, struct spi_message *message);
-+extern int spi_sync_locked(struct spi_device *spi, struct spi_message *message);
-+extern int spi_bus_lock(struct spi_master *master);
-+extern int spi_bus_unlock(struct spi_master *master);
-
- /**
- * spi_write - SPI synchronous write