[patch 2.6.15-rc5-mm3 3/3] SPI bitbanging becomes library code
From: David Brownell
Date: Sun Dec 18 2005 - 14:16:49 EST
This updates the SPI bitbanging support so it should be usable for
some common types of SPI hardware.
This updates the SPI bitbanging support:
- It's no longer a standalone driver, but is instead a library of code
for drivers to call.
- It should now support three different types of driver, all within
this task-per-controller implementation model.
* Pure bitbang. These can now provide word-at-a-time I/O loops
tuned for each SPI mode, possibly using assembly language.
* Word-at-a-time controllers. Some controllers essentially let
those I/O loops be handled by the hardware, and at common CPU
and SPI speeds a polling driver may be quite appropriate.
* Transfer-at-a-time controllers. It turns out that it's easy
to fit controllers with FIFOs, half-duplex restrictions, and
simple DMA support into the same framework.
- Some cleanups to the code actually banging bits.
That means a lot of hardware could work with this framework, though common
types of controller can't reach peak performance without switching to a
driver structure that supports pipelining of transfers (e.g. DMA queues)
and maybe controllers (e.g. IRQ driven).
Signed-off-by: David Brownell <dbrownell@xxxxxxxxxxxxxxxxxxxxx>
--- mm3.orig.orig/drivers/spi/Kconfig 2005-12-18 10:18:34.000000000 -0800
+++ mm3.orig/drivers/spi/Kconfig 2005-12-18 10:18:52.000000000 -0800
@@ -71,14 +71,14 @@ config SPI_BITBANG
depends on SPI_MASTER && EXPERIMENTAL
help
With a few GPIO pins, your system can bitbang the SPI protocol.
- Choose this if you need SPI support through I/O pins (GPIO,
- parallel port, etc).
-
- Make sure you initialize one platform device object for each SPI
- master device on your system, using "spi_bitbang" as the device
- name with platform_data saying how to use which pins. That will
- often be done using static board-specific tables in board-specific
- (or adapter-specific) setup code.
+ Select this to get SPI support through I/O pins (GPIO, parallel
+ port, etc). Or, some systems' SPI master controller drivers use
+ this code to manage the per-word or per-transfer accesses to the
+ hardware shift registers.
+
+ This is library code, and is automatically selected by drivers that
+ need it. You only need to select this explicitly to support driver
+ modules that aren't part of this kernel tree.
#
# Add new SPI master controllers in alphabetical order above this line
--- mm3.orig.orig/include/linux/spi/spi_bitbang.h 2005-12-18 10:18:34.000000000 -0800
+++ mm3.orig/include/linux/spi/spi_bitbang.h 2005-12-18 10:18:52.000000000 -0800
@@ -1,46 +1,67 @@
#ifndef __SPI_BITBANG_H
#define __SPI_BITBANG_H
-/* delarations for interface between core/algorithm and the part of the
- * driver that actually knows what pins do what
+/*
+ * Mix this utility code with some glue code to get one of several types of
+ * simple SPI master driver. Two do polled word-at-a-time I/O:
+ *
+ * - GPIO/parport bitbangers. Provide chipselect() and txrx_word[](),
+ * expanding the per-word routines from the inline templates below.
+ *
+ * - Drivers for controllers resembling bare shift registers. Provide
+ * chipselect() and txrx_word[](), with custom setup()/cleanup() methods
+ * that use your controller's clock and chipselect registers.
+ *
+ * Some hardware works well with requests at spi_transfer scope:
+ *
+ * - Drivers leveraging smarter hardware, with fifos or DMA; or for half
+ * duplex (MicroWire) controllers. Provide chipslect() and txrx_bufs(),
+ * and custom setup()/cleanup() methods.
*/
+struct spi_bitbang {
+ struct workqueue_struct *workqueue;
+ struct work_struct work;
+
+ spinlock_t lock;
+ struct list_head queue;
+ u8 busy;
+ u8 shutdown;
+ u8 use_dma;
-/**
- * struct spi_bitbang_plat_data - pass hardware-specific knowledge
- */
-struct spi_bitbang_plat_data {
- unsigned num_chipselect;
+ struct spi_master *master;
- /* enable/disable the chip; before enable, sets phase */
void (*chipselect)(struct spi_device *spi, int is_on);
- /* probably these should become txrx_mode0(), txrx_mode1(),
- * and so on, when speed matters.
- */
- u32 (*txrx_word)(struct spi_device *spi,
+ int (*txrx_bufs)(struct spi_device *spi, struct spi_transfer *t);
+ u32 (*txrx_word[4])(struct spi_device *spi,
unsigned nsecs,
u32 word, u8 bits);
};
-extern struct platform_driver spi_bitbang_driver;
-
-
-/* FIXME just name functions after SCK and MOSI */
-enum spi_bitbang_pin {
- SPI_BITBANG_SCK,
- SPI_BITBANG_MOSI,
-};
+/* you can call these default bitbang->master methods from your custom
+ * methods, if you like.
+ */
+extern int spi_bitbang_setup(struct spi_device *spi);
+extern void spi_bitbang_cleanup(const struct spi_device *spi);
+extern int spi_bitbang_transfer(struct spi_device *spi, struct spi_message *m);
+
+/* start or stop queue processing */
+extern int spi_bitbang_start(struct spi_bitbang *spi);
+extern int spi_bitbang_stop(struct spi_bitbang *spi);
#endif /* __SPI_BITBANG_H */
+/*-------------------------------------------------------------------------*/
+
#ifdef EXPAND_BITBANG_TXRX
/*
- * The code that knows what GPIO pins do what should have declared three
+ * The code that knows what GPIO pins do what should have declared four
* functions, ideally as inlines, before #defining EXPAND_BITBANG_TXRX
* and including this header:
*
- * void setpin(struct spi_device *, enum spi_bitbang_pin, int is_on);
+ * void setsck(struct spi_device *, int is_on);
+ * void setmosi(struct spi_device *, int is_on);
* int getmiso(struct spi_device *);
* void spidelay(unsigned);
*
@@ -50,33 +71,31 @@ enum spi_bitbang_pin {
*
* Since this is software, the timings may not be exactly what your board's
* chips need ... there may be several reasons you'd need to tweak timings
- * in this routine, not just make to make it faster or slower to match a
+ * in these routines, not just make to make it faster or slower to match a
* particular CPU clock rate.
*/
-// SPI_MODE_0 seems to work fine
-
static inline u32
bitbang_txrx_be_cpha0(struct spi_device *spi,
unsigned nsecs, unsigned cpol,
u32 word, u8 bits)
{
- /* if (cpol) this is SPI_MODE_0; else this is SPI_MODE_2 */
+ /* if (cpol == 0) this is SPI_MODE_0; else this is SPI_MODE_2 */
/* clock starts at inactive polarity */
for (word <<= (32 - bits); likely(bits); bits--) {
/* setup MSB (to slave) on trailing edge */
- setpin(spi, SPI_BITBANG_MOSI, word & (1 << 31));
+ setmosi(spi, word & (1 << 31));
spidelay(nsecs); /* T(setup) */
- setpin(spi, SPI_BITBANG_SCK, !cpol);
+ setsck(spi, !cpol);
spidelay(nsecs);
/* sample MSB (from slave) on leading edge */
word <<= 1;
word |= getmiso(spi);
- setpin(spi, SPI_BITBANG_SCK, cpol);
+ setsck(spi, cpol);
}
return word;
}
@@ -86,18 +105,18 @@ bitbang_txrx_be_cpha1(struct spi_device
unsigned nsecs, unsigned cpol,
u32 word, u8 bits)
{
- /* if (cpol) this is SPI_MODE_1; else this is SPI_MODE_3 */
+ /* if (cpol == 0) this is SPI_MODE_1; else this is SPI_MODE_3 */
/* clock starts at inactive polarity */
for (word <<= (32 - bits); likely(bits); bits--) {
/* setup MSB (to slave) on leading edge */
- setpin(spi, SPI_BITBANG_SCK, !cpol);
- setpin(spi, SPI_BITBANG_MOSI, word & (1 << 31));
- spidelay(nsecs);
+ setsck(spi, !cpol);
+ setmosi(spi, word & (1 << 31));
+ spidelay(nsecs); /* T(setup) */
- setpin(spi, SPI_BITBANG_SCK, cpol);
- spidelay(nsecs); /* T(setup) */
+ setsck(spi, cpol);
+ spidelay(nsecs);
/* sample MSB (from slave) on trailing edge */
word <<= 1;
--- mm3.orig.orig/drivers/spi/spi_bitbang.c 2005-12-18 10:18:34.000000000 -0800
+++ mm3.orig/drivers/spi/spi_bitbang.c 2005-12-18 10:18:52.000000000 -0800
@@ -1,5 +1,5 @@
/*
- * spi_bitbang.c - bitbanging SPI driver
+ * spi_bitbang.c - polling/bitbanging SPI master controller driver utilities
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
@@ -20,6 +20,7 @@
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/workqueue.h>
+#include <linux/interrupt.h>
#include <linux/delay.h>
#include <linux/errno.h>
#include <linux/platform_device.h>
@@ -28,37 +29,42 @@
#include <linux/spi/spi_bitbang.h>
-struct spi_bitbang {
- struct work_struct work;
- struct workqueue_struct *workqueue;
-
- spinlock_t lock;
- struct list_head queue;
-
- struct spi_master *master;
-
- void (*chipselect)(struct spi_device *spi, int is_on);
- u32 (*txrx_word)(struct spi_device *spi,
- unsigned nsecs,
- u32 word, u8 bits);
-};
+/*----------------------------------------------------------------------*/
-/* spi_bitbang_cs is in spi_device->controller_state.
+/*
+ * FIRST PART (OPTIONAL): word-at-a-time spi_transfer support.
+ * Use this for GPIO or shift-register level hardware APIs.
+ *
+ * spi_bitbang_cs is in spi_device->controller_state, which is unavailable
+ * to glue code. These bitbang setup() and cleanup() routines are always
+ * used, though maybe they're called from controller-aware code.
+ *
+ * chipselect() and friends may use use spi_device->controller_data and
+ * controller registers as appropriate.
*
- * chipselect() etc probably use use spi_device->controller_data
- * to remember chipselect, clock, and data i/o pins.
+ *
+ * NOTE: SPI controller pins can often be used as GPIO pins instead,
+ * which means you could use a bitbang driver either to get hardware
+ * working quickly, or testing for differences that aren't speed related.
*/
+
struct spi_bitbang_cs {
unsigned nsecs; /* (clock cycle time)/2 */
- unsigned (*txrx_buf)(struct spi_bitbang *, struct spi_device *,
+ u32 (*txrx_word)(struct spi_device *spi, unsigned nsecs,
+ u32 word, u8 bits);
+ unsigned (*txrx_bufs)(struct spi_device *,
+ u32 (*txrx_word)(
+ struct spi_device *spi,
+ unsigned nsecs,
+ u32 word, u8 bits),
unsigned, struct spi_transfer *);
};
-/*----------------------------------------------------------------------*/
-
static unsigned bitbang_txrx_8(
- struct spi_bitbang *bitbang,
struct spi_device *spi,
+ u32 (*txrx_word)(struct spi_device *spi,
+ unsigned nsecs,
+ u32 word, u8 bits),
unsigned ns,
struct spi_transfer *t
) {
@@ -72,7 +78,7 @@ static unsigned bitbang_txrx_8(
if (tx)
word = *tx++;
- word = bitbang->txrx_word(spi, ns, word, bits);
+ word = txrx_word(spi, ns, word, bits);
if (rx)
*rx++ = word;
count -= 1;
@@ -81,8 +87,10 @@ static unsigned bitbang_txrx_8(
}
static unsigned bitbang_txrx_16(
- struct spi_bitbang *bitbang,
struct spi_device *spi,
+ u32 (*txrx_word)(struct spi_device *spi,
+ unsigned nsecs,
+ u32 word, u8 bits),
unsigned ns,
struct spi_transfer *t
) {
@@ -96,7 +104,7 @@ static unsigned bitbang_txrx_16(
if (tx)
word = *tx++;
- word = bitbang->txrx_word(spi, ns, word, bits);
+ word = txrx_word(spi, ns, word, bits);
if (rx)
*rx++ = word;
count -= 2;
@@ -105,8 +113,10 @@ static unsigned bitbang_txrx_16(
}
static unsigned bitbang_txrx_32(
- struct spi_bitbang *bitbang,
struct spi_device *spi,
+ u32 (*txrx_word)(struct spi_device *spi,
+ unsigned nsecs,
+ u32 word, u8 bits),
unsigned ns,
struct spi_transfer *t
) {
@@ -120,7 +130,7 @@ static unsigned bitbang_txrx_32(
if (tx)
word = *tx++;
- word = bitbang->txrx_word(spi, ns, word, bits);
+ word = txrx_word(spi, ns, word, bits);
if (rx)
*rx++ = word;
count -= 4;
@@ -128,16 +138,111 @@ static unsigned bitbang_txrx_32(
return t->len - count;
}
+/**
+ * spi_bitbang_setup - default setup for per-word I/O loops
+ */
+int spi_bitbang_setup(struct spi_device *spi)
+{
+ struct spi_bitbang_cs *cs = spi->controller_state;
+ struct spi_bitbang *bitbang;
+
+ if (!cs) {
+ cs = kzalloc(sizeof *cs, SLAB_KERNEL);
+ if (!cs)
+ return -ENOMEM;
+ spi->controller_state = cs;
+ }
+ bitbang = spi_master_get_devdata(spi->master);
+
+ if (!spi->bits_per_word)
+ spi->bits_per_word = 8;
+
+ /* spi_transfer level calls that work per-word */
+ if (spi->bits_per_word <= 8)
+ cs->txrx_bufs = bitbang_txrx_8;
+ else if (spi->bits_per_word <= 16)
+ cs->txrx_bufs = bitbang_txrx_16;
+ else if (spi->bits_per_word <= 32)
+ cs->txrx_bufs = bitbang_txrx_32;
+ else
+ return -EINVAL;
+
+ /* per-word shift register access, in hardware or bitbanging */
+ cs->txrx_word = bitbang->txrx_word[spi->mode & (SPI_CPOL|SPI_CPHA)];
+ if (!cs->txrx_word)
+ return -EINVAL;
+
+ if (!spi->max_speed_hz)
+ spi->max_speed_hz = 500 * 1000;
+
+ /* nsecs = max(50, (clock period)/2), be optimistic */
+ cs->nsecs = (1000000000/2) / (spi->max_speed_hz);
+ if (cs->nsecs < 50)
+ cs->nsecs = 50;
+ if (cs->nsecs > MAX_UDELAY_MS * 1000)
+ return -EINVAL;
+
+ dev_dbg(&spi->dev, "%s, mode %d, %u bits/w, %u nsec\n",
+ __FUNCTION__, spi->mode & (SPI_CPOL | SPI_CPHA),
+ spi->bits_per_word, 2 * cs->nsecs);
+
+ /* NOTE we _need_ to call chipselect() early, ideally with adapter
+ * setup, unless the hardware defaults cooperate to avoid confusion
+ * between normal (active low) and inverted chipselects.
+ */
+
+ /* deselect chip (low or high) */
+ spin_lock(&bitbang->lock);
+ if (!bitbang->busy) {
+ bitbang->chipselect(spi, 0);
+ ndelay(cs->nsecs);
+ }
+ spin_unlock(&bitbang->lock);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(spi_bitbang_setup);
+
+/**
+ * spi_bitbang_cleanup - default cleanup for per-word I/O loops
+ */
+void spi_bitbang_cleanup(const struct spi_device *spi)
+{
+ kfree(spi->controller_state);
+}
+EXPORT_SYMBOL_GPL(spi_bitbang_cleanup);
+
+static int spi_bitbang_bufs(struct spi_device *spi, struct spi_transfer *t)
+{
+ struct spi_bitbang_cs *cs = spi->controller_state;
+ unsigned nsecs = cs->nsecs;
+
+ return cs->txrx_bufs(spi, cs->txrx_word, nsecs, t);
+}
+
+/*----------------------------------------------------------------------*/
+
+/*
+ * SECOND PART ... simple transfer queue runner.
+ *
+ * This costs a task context per controller, running the queue by
+ * performing each transfer in sequence. Smarter hardware can queue
+ * several DMA transfers at once, and process several controller queues
+ * in parallel; this driver doesn't match such hardware very well.
+ *
+ * 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(void *_bitbang)
{
struct spi_bitbang *bitbang = _bitbang;
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;
- struct spi_bitbang_cs *cs;
unsigned nsecs;
struct spi_transfer *t;
unsigned tmp;
@@ -149,19 +254,22 @@ static void bitbang_work(void *_bitbang)
list_del_init(&m->queue);
spin_unlock_irqrestore(&bitbang->lock, flags);
+// FIXME this is made-up
+nsecs = 100;
+
spi = m->spi;
- cs = spi->controller_state;
- nsecs = cs->nsecs;
t = m->transfers;
tmp = 0;
chipselect = 0;
status = 0;
- ndelay(nsecs);
-
for (;;t++) {
+ if (bitbang->shutdown) {
+ status = -ESHUTDOWN;
+ break;
+ }
- /* set up default clock polarity and select */
+ /* set up default clock polarity, and activate chip */
if (!chipselect) {
bitbang->chipselect(spi, 1);
ndelay(nsecs);
@@ -172,7 +280,13 @@ static void bitbang_work(void *_bitbang)
}
/* transfer data */
- status = cs->txrx_buf(bitbang, spi, nsecs, t);
+ if (t->len) {
+ /* FIXME if bitbang->use_dma, dma_map_single()
+ * before the transfer, and dma_unmap_single()
+ * afterwards, for either or both buffers...
+ */
+ status = bitbang->txrx_bufs(spi, t);
+ }
if (status != t->len) {
if (status > 0)
status = -EMSGSIZE;
@@ -211,70 +325,24 @@ static void bitbang_work(void *_bitbang)
spin_lock_irqsave(&bitbang->lock, flags);
}
+ bitbang->busy = 0;
spin_unlock_irqrestore(&bitbang->lock, flags);
-
-}
-
-/*----------------------------------------------------------------------*/
-
-static int bitbang_setup(struct spi_device *spi)
-{
- struct spi_bitbang_cs *cs = spi->controller_state;
- struct spi_bitbang *bitbang;
-
- if (!cs) {
- cs = kzalloc(sizeof *cs, SLAB_KERNEL);
- if (!cs)
- return -ENOMEM;
- spi->controller_state = cs;
- }
- bitbang = class_get_devdata(&spi->master->cdev);
-
- if (!spi->bits_per_word)
- spi->bits_per_word = 8;
- if (spi->bits_per_word <= 8)
- cs->txrx_buf = bitbang_txrx_8;
- else if (spi->bits_per_word <= 16)
- cs->txrx_buf = bitbang_txrx_16;
- else if (spi->bits_per_word <= 32)
- cs->txrx_buf = bitbang_txrx_32;
- else
- return -EINVAL;
-
- if (!spi->max_speed_hz)
- spi->max_speed_hz = 500 * 1000;
-
- /* nsecs = max(50, (clock period)/2), be optimistic */
- cs->nsecs = (1000000000/2) / (spi->max_speed_hz);
- if (cs->nsecs < 50)
- cs->nsecs = 50;
- if (cs->nsecs > MAX_UDELAY_MS * 1000)
- return -EINVAL;
-
- dev_dbg(&spi->dev, "%s, mode %d, %u bits/w, %u nsec\n",
- __FUNCTION__, spi->mode & (SPI_CPOL | SPI_CPHA),
- spi->bits_per_word, 2 * cs->nsecs);
-
- /* deselect chip (low or high) */
- bitbang->chipselect(spi, 0);
- ndelay(cs->nsecs);
- return 0;
}
-static void bitbang_cleanup(const struct spi_device *spi)
-{
- kfree(spi->controller_state);
-}
-
-static int bitbang_transfer(struct spi_device *spi, struct spi_message *m)
+/**
+ * spi_bitbang_transfer - default submit to transfer queue
+ */
+int spi_bitbang_transfer(struct spi_device *spi, struct spi_message *m)
{
struct spi_bitbang *bitbang;
unsigned long flags;
m->actual_length = 0;
- m->status = 0;
+ m->status = -EINPROGRESS;
- bitbang = class_get_devdata(&spi->master->cdev);
+ bitbang = spi_master_get_devdata(spi->master);
+ if (bitbang->shutdown)
+ return -ESHUTDOWN;
spin_lock_irqsave(&bitbang->lock, flags);
list_add_tail(&m->queue, &bitbang->queue);
@@ -283,54 +351,59 @@ static int bitbang_transfer(struct spi_d
return 0;
}
+EXPORT_SYMBOL_GPL(spi_bitbang_transfer);
/*----------------------------------------------------------------------*/
-static int __devinit bitbang_probe(struct platform_device *pdev)
+/**
+ * spi_bitbang_start - start up a polled/bitbanging SPI master driver
+ * @bitbang: driver handle
+ *
+ * Caller should have zero-initialized all parts of the structure, and then
+ * provided callbacks for chip selection and I/O loops. If the master has
+ * a transfer method, its final step should call spi_bitbang_transfer; or,
+ * that's the default if the transfer routine is not initialized. It should
+ * also set up the bus number and number of chipselects.
+ *
+ * For i/o loops, provide callbacks either per-word (for bitbanging, or for
+ * hardware that basically exposes a shift register) or per-spi_transfer
+ * (which takes better advantage of hardware like fifos or DMA engines).
+ *
+ * Drivers using per-word I/O loops should use (or call) spi_bitbang_setup and
+ * spi_bitbang_cleanup to handle those spi master methods. Those methods are
+ * the defaults if the bitbang->txrx_bufs routine isn't initialized.
+ *
+ * This routine registers the spi_master, which will process requests in a
+ * dedicated task, keeping IRQs unblocked most of the time. To stop
+ * processing those requests, call spi_bitbang_stop().
+ */
+int spi_bitbang_start(struct spi_bitbang *bitbang)
{
- struct spi_bitbang_plat_data *pdata = pdev->dev.platform_data;
- struct spi_master *master;
- struct spi_bitbang *bitbang;
- int status;
+ int status;
- if (!pdata)
+ if (!bitbang->master || !bitbang->chipselect)
return -EINVAL;
- master = spi_alloc_master(&pdev->dev, sizeof *bitbang);
- if (!master)
- return -ENOMEM;
-
- if (pdev->id != -1)
- master->bus_num = pdev->id;
- master->setup = bitbang_setup;
- master->transfer = bitbang_transfer;
- master->cleanup = bitbang_cleanup;
- master->num_chipselect = pdata->num_chipselect;
-
- bitbang = class_get_devdata(&master->cdev);
- bitbang->chipselect = pdata->chipselect;
- bitbang->txrx_word = pdata->txrx_word;
-
INIT_WORK(&bitbang->work, bitbang_work, bitbang);
spin_lock_init(&bitbang->lock);
INIT_LIST_HEAD(&bitbang->queue);
- bitbang->master = master;
-
- if (class_device_get(&master->cdev) == NULL) {
- status = -ENOMEM;
- goto err0;
- }
- /* bridging code is allowed to know that this is where
- * the spi_master is stored ... so it can then for example
- * use that with spi_new_device().
- */
- dev_set_drvdata(&pdev->dev, master);
+ if (!bitbang->master->transfer)
+ bitbang->master->transfer = spi_bitbang_transfer;
+ if (!bitbang->txrx_bufs) {
+ bitbang->use_dma = 0;
+ bitbang->txrx_bufs = spi_bitbang_bufs;
+ if (!bitbang->master->setup) {
+ bitbang->master->setup = spi_bitbang_setup;
+ bitbang->master->cleanup = spi_bitbang_cleanup;
+ }
+ } else if (!bitbang->master->setup)
+ return -EINVAL;
- /* this task is the only thing to touch the SPI bits.
- * it's OK if clock cycles stretch when it gets preempted
- */
- bitbang->workqueue = create_singlethread_workqueue(pdev->dev.bus_id);
+ /* this task is the only thing to touch the SPI bits */
+ bitbang->busy = 0;
+ bitbang->workqueue = create_singlethread_workqueue(
+ bitbang->master->cdev.dev->bus_id);
if (bitbang->workqueue == NULL) {
status = -EBUSY;
goto err1;
@@ -339,7 +412,7 @@ static int __devinit bitbang_probe(struc
/* driver may get busy before register() returns, especially
* if someone registered boardinfo for devices
*/
- status = spi_register_master(master);
+ status = spi_register_master(bitbang->master);
if (status < 0)
goto err2;
@@ -348,55 +421,40 @@ static int __devinit bitbang_probe(struc
err2:
destroy_workqueue(bitbang->workqueue);
err1:
- class_device_put(&master->cdev);
-err0:
return status;
}
+EXPORT_SYMBOL_GPL(spi_bitbang_start);
-static int __devexit bitbang_remove(struct platform_device *pdev)
+/**
+ * spi_bitbang_stop - stops the task providing spi communication
+ */
+int spi_bitbang_stop(struct spi_bitbang *bitbang)
{
- struct spi_master *master;
- struct spi_bitbang *bitbang;
+ unsigned limit = 500;
- master = dev_get_drvdata(&pdev->dev);
- bitbang = class_get_devdata(&master->cdev);
+ spin_lock_irq(&bitbang->lock);
+ bitbang->shutdown = 0;
+ while (!list_empty(&bitbang->queue) && limit--) {
+ spin_unlock_irq(&bitbang->lock);
- /* NOTE: assumes that all children were already cleaned up,
- * which also means there will be no pending requests...
- */
- WARN_ON(!list_empty(&bitbang->queue));
- WARN_ON(!list_empty(&pdev->dev.klist_children.k_list));
-
- destroy_workqueue(bitbang->workqueue);
- class_device_put(&master->cdev);
- spi_unregister_master(master);
-
- return 0;
-}
+ dev_dbg(bitbang->master->cdev.dev, "wait for queue\n");
+ msleep(10);
-struct platform_driver spi_bitbang_driver = {
- .driver = {
- .name = "spi_bitbang",
- .owner = THIS_MODULE,
- },
- .probe = bitbang_probe,
- .remove = __devexit_p(bitbang_remove),
- // suspend, resume ... stop queue after current message, restart later
-};
-EXPORT_SYMBOL_GPL(spi_bitbang_driver);
+ spin_lock_irq(&bitbang->lock);
+ }
+ spin_unlock_irq(&bitbang->lock);
+ if (!list_empty(&bitbang->queue)) {
+ dev_err(bitbang->master->cdev.dev, "queue didn't empty\n");
+ return -EBUSY;
+ }
+ destroy_workqueue(bitbang->workqueue);
-static int __init bitbang_init(void)
-{
- return platform_driver_register(&spi_bitbang_driver);
-}
-device_initcall(bitbang_init);
+ spi_unregister_master(bitbang->master);
-static void __exit bitbang_exit(void)
-{
- platform_driver_unregister(&spi_bitbang_driver);
+ return 0;
}
-module_exit(bitbang_exit);
+EXPORT_SYMBOL_GPL(spi_bitbang_stop);
MODULE_LICENSE("GPL");