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Message-ID: <20090228081117.31964.51155.stgit@fedora.yogi>
Date: Sat, 28 Feb 2009 13:41:17 +0530
From: Balaji Rao <balajirrao@...nmoko.org>
To: linux-kernel@...r.kernel.org
Cc: David Brownell <dbrownell@...rs.sourceforge.net>,
Andy Green <andy@...nmoko.com>,
Simon Kagstrom <simon.kagstrom@...il.com>,
spi-devel-general@...ts.sourceforge.net
Subject: [PATCH 2/2] spi_bitbang: Add support for non-blocking synchronous
transfers
The synchronous transfer code in bitbang_work workqueue function is
refactored into a spearate function which optionally becomes the master's
transfer_sync method.
Some initial part of the work was done by Simon Kagstrom.
Signed-off-by: Balaji Rao <balajirrao@...nmoko.org>
Signed-off-by: Simon Kagstrom <simon.kagstrom@...il.com>
Cc: Andy Green <andy@...nmoko.com>
Cc: David Brownell <dbrownell@...rs.sourceforge.net>
Cc: spi-devel-general@...ts.sourceforge.net
---
drivers/spi/spi_bitbang.c | 227 +++++++++++++++++++++------------------
include/linux/spi/spi_bitbang.h | 5 +
2 files changed, 125 insertions(+), 107 deletions(-)
diff --git a/drivers/spi/spi_bitbang.c b/drivers/spi/spi_bitbang.c
index 85e61f4..39dd736 100644
--- a/drivers/spi/spi_bitbang.c
+++ b/drivers/spi/spi_bitbang.c
@@ -264,130 +264,140 @@ static int spi_bitbang_bufs(struct spi_device *spi, struct spi_transfer *t)
* Drivers can provide word-at-a-time i/o primitives, or provide
* transfer-at-a-time ones to leverage dma or fifo hardware.
*/
-static void bitbang_work(struct work_struct *work)
-{
- struct spi_bitbang *bitbang =
- container_of(work, struct spi_bitbang, work);
- unsigned long flags;
-
- spin_lock_irqsave(&bitbang->lock, flags);
- bitbang->busy = 1;
- while (!list_empty(&bitbang->queue)) {
- struct spi_message *m;
- struct spi_device *spi;
- unsigned nsecs;
- struct spi_transfer *t = NULL;
- unsigned tmp;
- unsigned cs_change;
- int status;
- int (*setup_transfer)(struct spi_device *,
- struct spi_transfer *);
- m = container_of(bitbang->queue.next, struct spi_message,
- queue);
- list_del_init(&m->queue);
- spin_unlock_irqrestore(&bitbang->lock, flags);
+/* Synchronous non blocking transfer */
+int
+spi_bitbang_transfer_sync(struct spi_device *spi, struct spi_message *m)
+{
+ struct spi_bitbang *bitbang = spi_master_get_devdata(spi->master);
+ struct spi_transfer *t;
+ unsigned long flags;
+ int cs_change = 1;
+ int status;
+ int nsecs;
+ int (*setup_transfer)(struct spi_device *, struct spi_transfer *);
+
+ /* FIXME this is made-up ... the correct value is known to
+ * word-at-a-time bitbang code, and presumably chipselect()
+ * should enforce these requirements too?
+ */
+ nsecs = 100;
+ cs_change = 1;
+ status = 0;
+ setup_transfer = NULL;
+
+ local_irq_save(flags);
+ list_for_each_entry(t, &m->transfers, transfer_list) {
+ /* override or restore speed and wordsize */
+ if (t->speed_hz || t->bits_per_word) {
+ setup_transfer = bitbang->setup_transfer;
+ if (!setup_transfer) {
+ status = -ENOPROTOOPT;
+ break;
+ }
+ }
+ if (setup_transfer) {
+ status = setup_transfer(spi, t);
+ if (status < 0)
+ break;
+ }
- /* FIXME this is made-up ... the correct value is known to
- * word-at-a-time bitbang code, and presumably chipselect()
- * should enforce these requirements too?
+ /* set up default clock polarity, and activate chip;
+ * this implicitly updates clock and spi modes as
+ * previously recorded for this device via setup().
+ * (and also deselects any other chip that might be
+ * selected ...)
*/
- nsecs = 100;
-
- spi = m->spi;
- tmp = 0;
- cs_change = 1;
- status = 0;
- setup_transfer = NULL;
- list_for_each_entry (t, &m->transfers, transfer_list) {
-
- /* override or restore speed and wordsize */
- if (t->speed_hz || t->bits_per_word) {
- setup_transfer = bitbang->setup_transfer;
- if (!setup_transfer) {
- status = -ENOPROTOOPT;
- break;
- }
- }
- if (setup_transfer) {
- status = setup_transfer(spi, t);
- if (status < 0)
- break;
- }
+ if (cs_change) {
+ bitbang->chipselect(spi, BITBANG_CS_ACTIVE);
+ ndelay(nsecs);
+ }
- /* set up default clock polarity, and activate chip;
- * this implicitly updates clock and spi modes as
- * previously recorded for this device via setup().
- * (and also deselects any other chip that might be
- * selected ...)
- */
- if (cs_change) {
- bitbang->chipselect(spi, BITBANG_CS_ACTIVE);
- ndelay(nsecs);
- }
- cs_change = t->cs_change;
- if (!t->tx_buf && !t->rx_buf && t->len) {
- status = -EINVAL;
- break;
- }
+ cs_change = t->cs_change;
+ if (!t->tx_buf && !t->rx_buf && t->len) {
+ status = -EINVAL;
+ break;
+ }
- /* transfer data. the lower level code handles any
- * new dma mappings it needs. our caller always gave
- * us dma-safe buffers.
+ /* transfer data. the lower level code handles any
+ * new dma mappings it needs. our caller always gave
+ * us dma-safe buffers.
+ */
+ if (t->len) {
+ /* REVISIT dma API still needs a designated
+ * DMA_ADDR_INVALID; ~0 might be better.
*/
- if (t->len) {
- /* REVISIT dma API still needs a designated
- * DMA_ADDR_INVALID; ~0 might be better.
- */
- if (!m->is_dma_mapped)
- t->rx_dma = t->tx_dma = 0;
- status = bitbang->txrx_bufs(spi, t);
- }
- if (status > 0)
- m->actual_length += status;
- if (status != t->len) {
- /* always report some kind of error */
- if (status >= 0)
- status = -EREMOTEIO;
- break;
- }
- status = 0;
+ if (!m->is_dma_mapped)
+ t->rx_dma = t->tx_dma = 0;
+ status = bitbang->txrx_bufs(spi, t);
+ }
+ if (status > 0)
+ m->actual_length += status;
+ if (status != t->len) {
+ /* always report some kind of error */
+ if (status >= 0)
+ status = -EREMOTEIO;
+ break;
+ }
+ status = 0;
/* protocol tweaks before next transfer */
- if (t->delay_usecs)
- udelay(t->delay_usecs);
-
+ if (t->delay_usecs)
+ udelay(t->delay_usecs);
if (!cs_change)
continue;
- if (t->transfer_list.next == &m->transfers)
- break;
-
+ if (t->transfer_list.next == &m->transfers)
+ break;
/* sometimes a short mid-message deselect of the chip
- * may be needed to terminate a mode or command
- */
- ndelay(nsecs);
- bitbang->chipselect(spi, BITBANG_CS_INACTIVE);
- ndelay(nsecs);
- }
+ * may be needed to terminate a mode or command
+ */
+ ndelay(nsecs);
+ bitbang->chipselect(spi, BITBANG_CS_INACTIVE);
+ ndelay(nsecs);
+ }
- m->status = status;
+ m->status = status;
+ if (m->complete)
m->complete(m->context);
- /* restore speed and wordsize */
- if (setup_transfer)
- setup_transfer(spi, NULL);
+ /* restore speed and wordsize */
+ if (setup_transfer)
+ setup_transfer(spi, NULL);
- /* normally deactivate chipselect ... unless no error and
- * cs_change has hinted that the next message will probably
- * be for this chip too.
- */
- if (!(status == 0 && cs_change)) {
- ndelay(nsecs);
- bitbang->chipselect(spi, BITBANG_CS_INACTIVE);
- ndelay(nsecs);
- }
+ /* normally deactivate chipselect ... unless no error and
+ * cs_change has hinted that the next message will probably
+ * be for this chip too.
+ */
+ if (!(status == 0 && cs_change)) {
+ ndelay(nsecs);
+ bitbang->chipselect(spi, BITBANG_CS_INACTIVE);
+ ndelay(nsecs);
+ }
+ local_irq_restore(flags);
+
+ return status;
+}
+EXPORT_SYMBOL_GPL(spi_bitbang_transfer_sync);
+
+static void bitbang_work(struct work_struct *work)
+{
+ struct spi_bitbang *bitbang =
+ container_of(work, struct spi_bitbang, work);
+ unsigned long flags;
+
+ spin_lock_irqsave(&bitbang->lock, flags);
+ bitbang->busy = 1;
+ while (!list_empty(&bitbang->queue)) {
+ struct spi_message *m;
+
+ m = container_of(bitbang->queue.next, struct spi_message,
+ queue);
+ list_del_init(&m->queue);
+
+ spin_unlock_irqrestore(&bitbang->lock, flags);
+ spi_bitbang_transfer_sync(m->spi, m);
spin_lock_irqsave(&bitbang->lock, flags);
}
bitbang->busy = 0;
@@ -459,6 +469,9 @@ int spi_bitbang_start(struct spi_bitbang *bitbang)
if (!bitbang->master->transfer)
bitbang->master->transfer = spi_bitbang_transfer;
+ if (!bitbang->master->transfer_sync && bitbang->non_blocking_transfer)
+ bitbang->master->transfer_sync = spi_bitbang_transfer_sync;
+
if (!bitbang->txrx_bufs) {
bitbang->use_dma = 0;
bitbang->txrx_bufs = spi_bitbang_bufs;
diff --git a/include/linux/spi/spi_bitbang.h b/include/linux/spi/spi_bitbang.h
index eed4254..b99ed8d 100644
--- a/include/linux/spi/spi_bitbang.h
+++ b/include/linux/spi/spi_bitbang.h
@@ -31,6 +31,9 @@ struct spi_bitbang {
u8 use_dma;
u8 flags; /* extra spi->mode support */
+ /* Support for synchronous non blocking transfers */
+ int non_blocking_transfer;
+
struct spi_master *master;
/* setup_transfer() changes clock and/or wordsize to match settings
@@ -60,6 +63,8 @@ struct spi_bitbang {
extern int spi_bitbang_setup(struct spi_device *spi);
extern void spi_bitbang_cleanup(struct spi_device *spi);
extern int spi_bitbang_transfer(struct spi_device *spi, struct spi_message *m);
+extern int spi_bitbang_transfer_sync(struct spi_device *spi,
+ struct spi_message *m);
extern int spi_bitbang_setup_transfer(struct spi_device *spi,
struct spi_transfer *t);
--
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