@@ -124,6 +124,9 @@ struct spi_pram {
#define SPI_PRAM_SIZE 0x100
#define SPI_MRBLR ((unsigned int)PAGE_SIZE)
+/* value for 'locked' variable to indicate that the bus is unlocked */
+#define SPIBUS_UNLOCKED 0xFF
+
/* SPI Controller driver's private data. */
struct mpc8xxx_spi {
struct device *dev;
@@ -171,6 +174,8 @@ struct mpc8xxx_spi {
spinlock_t lock;
struct completion done;
+
+ u8 locked; /* chipselect number if bus is locked */
};
static void *mpc8xxx_dummy_rx;
@@ -605,11 +610,39 @@ static void mpc8xxx_spi_work(struct work
{
struct mpc8xxx_spi *mpc8xxx_spi = container_of(work, struct mpc8xxx_spi,
work);
+ u8 locked_cs;
+ u8 next_cs;
spin_lock_irq(&mpc8xxx_spi->lock);
while (!list_empty(&mpc8xxx_spi->queue)) {
struct spi_message *m = container_of(mpc8xxx_spi->queue.next,
struct spi_message, queue);
+ struct spi_message *msg = NULL;
+
+ if (mpc8xxx_spi->locked != SPIBUS_UNLOCKED) {
+ locked_cs = mpc8xxx_spi->locked;
+ next_cs = m->spi->chip_select;
+
+ if (next_cs != locked_cs) {
+ list_for_each_entry(msg, &mpc8xxx_spi->queue,
+ queue) {
+ next_cs = msg->spi->chip_select;
+ if (next_cs == locked_cs) {
+ m = msg;
+ break;
+ }
+ }
+
+ /*
+ * Do nothing even if there are messages
+ * for other devices
+ */
+ if (next_cs != locked_cs) {
+ spin_unlock_irq(&mpc8xxx_spi->lock);
+ return;
+ }
+ }
+ }
list_del_init(&m->queue);
spin_unlock_irq(&mpc8xxx_spi->lock);
@@ -736,6 +769,50 @@ static irqreturn_t mpc8xxx_spi_irq(s32 i
return ret;
}
+/*
+ * lock the spi bus for exclusive access
+ */
+static int mpc8xxx_spi_lock_bus(struct spi_device *spi)
+{
+ struct mpc8xxx_spi *mpc8xxx_spi = spi_master_get_devdata(spi->master);
+ unsigned long flags;
+
+ spin_lock_irqsave(&mpc8xxx_spi->lock, flags);
+ if (mpc8xxx_spi->locked != SPIBUS_UNLOCKED) {
+ spin_unlock_irqrestore(&mpc8xxx_spi->lock, flags);
+ return -ENOLCK;
+ }
+ mpc8xxx_spi->locked = spi->chip_select;
+
+ spin_unlock_irqrestore(&mpc8xxx_spi->lock, flags);
+
+ return 0;
+}
+
+/*
+ * unlock the spi bus from exclusive access
+ */
+static int mpc8xxx_spi_unlock_bus(struct spi_device *spi)
+{
+ struct mpc8xxx_spi *mpc8xxx_spi = spi_master_get_devdata(spi->master);
+ unsigned long flags;
+
+ spin_lock_irqsave(&mpc8xxx_spi->lock, flags);
+
+ /* remove the spi bus lock */
+ mpc8xxx_spi->locked = SPIBUS_UNLOCKED;
+
+ /*
+ * process all deferred messages for all chipselects
+ * other than the locked after the bus became unlocked
+ */
+ queue_work(mpc8xxx_spi->workqueue, &mpc8xxx_spi->work);
+
+ spin_unlock_irqrestore(&mpc8xxx_spi->lock, flags);
+
+ return 0;
+}
+
static int mpc8xxx_spi_transfer(struct spi_device *spi,
struct spi_message *m)
{
@@ -992,6 +1069,8 @@ mpc8xxx_spi_probe(struct device *dev, st
master->setup = mpc8xxx_spi_setup;
master->transfer = mpc8xxx_spi_transfer;
master->cleanup = mpc8xxx_spi_cleanup;
+ master->lock_bus = mpc8xxx_spi_lock_bus;
+ master->unlock_bus = mpc8xxx_spi_unlock_bus;
mpc8xxx_spi = spi_master_get_devdata(master);
mpc8xxx_spi->dev = dev;
@@ -999,6 +1078,7 @@ mpc8xxx_spi_probe(struct device *dev, st
mpc8xxx_spi->get_tx = mpc8xxx_spi_tx_buf_u8;
mpc8xxx_spi->flags = pdata->flags;
mpc8xxx_spi->spibrg = pdata->sysclk;
+ mpc8xxx_spi->locked = SPIBUS_UNLOCKED;
ret = mpc8xxx_spi_cpm_init(mpc8xxx_spi);
if (ret)