- 根目录:
- drivers
- spi
- spi.c
/*
* SPI init/core code
*
* Copyright (C) 2005 David Brownell
*
* 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
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include <linux/kernel.h>
#include <linux/device.h>
#include <linux/init.h>
#include <linux/cache.h>
#include <linux/mutex.h>
#include <linux/of_device.h>
#include <linux/slab.h>
#include <linux/mod_devicetable.h>
#include <linux/spi/spi.h>
#include <linux/of_spi.h>
#include <linux/pm_runtime.h>
#include <linux/export.h>
static void spidev_release(struct device *dev)
{
struct spi_device *spi = to_spi_device(dev);
/* spi masters may cleanup for released devices */
if (spi->master->cleanup)
spi->master->cleanup(spi);
spi_master_put(spi->master);
kfree(spi);
}
static ssize_t
modalias_show(struct device *dev, struct device_attribute *a, char *buf)
{
const struct spi_device *spi = to_spi_device(dev);
return sprintf(buf, "%s\n", spi->modalias);
}
static struct device_attribute spi_dev_attrs[] = {
__ATTR_RO(modalias),
__ATTR_NULL,
};
/* modalias support makes "modprobe $MODALIAS" new-style hotplug work,
* and the sysfs version makes coldplug work too.
*/
static const struct spi_device_id *spi_match_id(const struct spi_device_id *id,
const struct spi_device *sdev)
{
while (id->name[0]) {
if (!strcmp(sdev->modalias, id->name))
return id;
id++;
}
return NULL;
}
const struct spi_device_id *spi_get_device_id(const struct spi_device *sdev)
{
const struct spi_driver *sdrv = to_spi_driver(sdev->dev.driver);
return spi_match_id(sdrv->id_table, sdev);
}
EXPORT_SYMBOL_GPL(spi_get_device_id);
static int spi_match_device(struct device *dev, struct device_driver *drv)
{
const struct spi_device *spi = to_spi_device(dev);
const struct spi_driver *sdrv = to_spi_driver(drv);
/* Attempt an OF style match */
if (of_driver_match_device(dev, drv))
return 1;
if (sdrv->id_table)
return !!spi_match_id(sdrv->id_table, spi);
return strcmp(spi->modalias, drv->name) == 0;
}
static int spi_uevent(struct device *dev, struct kobj_uevent_env *env)
{
const struct spi_device *spi = to_spi_device(dev);
add_uevent_var(env, "MODALIAS=%s%s", SPI_MODULE_PREFIX, spi->modalias);
return 0;
}
#ifdef CONFIG_PM_SLEEP
static int spi_legacy_suspend(struct device *dev, pm_message_t message)
{
int value = 0;
struct spi_driver *drv = to_spi_driver(dev->driver);
/* suspend will stop irqs and dma; no more i/o */
if (drv) {
if (drv->suspend)
value = drv->suspend(to_spi_device(dev), message);
else
dev_dbg(dev, "... can't suspend\n");
}
return value;
}
static int spi_legacy_resume(struct device *dev)
{
int value = 0;
struct spi_driver *drv = to_spi_driver(dev->driver);
/* resume may restart the i/o queue */
if (drv) {
if (drv->resume)
value = drv->resume(to_spi_device(dev));
else
dev_dbg(dev, "... can't resume\n");
}
return value;
}
static int spi_pm_suspend(struct device *dev)
{
const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
if (pm)
return pm_generic_suspend(dev);
else
return spi_legacy_suspend(dev, PMSG_SUSPEND);
}
static int spi_pm_resume(struct device *dev)
{
const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
if (pm)
return pm_generic_resume(dev);
else
return spi_legacy_resume(dev);
}
static int spi_pm_freeze(struct device *dev)
{
const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
if (pm)
return pm_generic_freeze(dev);
else
return spi_legacy_suspend(dev, PMSG_FREEZE);
}
static int spi_pm_thaw(struct device *dev)
{
const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
if (pm)
return pm_generic_thaw(dev);
else
return spi_legacy_resume(dev);
}
static int spi_pm_poweroff(struct device *dev)
{
const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
if (pm)
return pm_generic_poweroff(dev);
else
return spi_legacy_suspend(dev, PMSG_HIBERNATE);
}
static int spi_pm_restore(struct device *dev)
{
const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
if (pm)
return pm_generic_restore(dev);
else
return spi_legacy_resume(dev);
}
#else
#define spi_pm_suspend NULL
#define spi_pm_resume NULL
#define spi_pm_freeze NULL
#define spi_pm_thaw NULL
#define spi_pm_poweroff NULL
#define spi_pm_restore NULL
#endif
static const struct dev_pm_ops spi_pm = {
.suspend = spi_pm_suspend,
.resume = spi_pm_resume,
.freeze = spi_pm_freeze,
.thaw = spi_pm_thaw,
.poweroff = spi_pm_poweroff,
.restore = spi_pm_restore,
SET_RUNTIME_PM_OPS(
pm_generic_runtime_suspend,
pm_generic_runtime_resume,
pm_generic_runtime_idle
)
};
struct bus_type spi_bus_type = {
.name = "spi",
.dev_attrs = spi_dev_attrs,
.match = spi_match_device,
.uevent = spi_uevent,
.pm = &spi_pm,
};
EXPORT_SYMBOL_GPL(spi_bus_type);
static int spi_drv_probe(struct device *dev)
{
const struct spi_driver *sdrv = to_spi_driver(dev->driver);
return sdrv->probe(to_spi_device(dev));
}
static int spi_drv_remove(struct device *dev)
{
const struct spi_driver *sdrv = to_spi_driver(dev->driver);
return sdrv->remove(to_spi_device(dev));
}
static void spi_drv_shutdown(struct device *dev)
{
const struct spi_driver *sdrv = to_spi_driver(dev->driver);
sdrv->shutdown(to_spi_device(dev));
}
/**
* spi_register_driver - register a SPI driver
* @sdrv: the driver to register
* Context: can sleep
*/
int spi_register_driver(struct spi_driver *sdrv)
{
sdrv->driver.bus = &spi_bus_type;
if (sdrv->probe)
sdrv->driver.probe = spi_drv_probe;
if (sdrv->remove)
sdrv->driver.remove = spi_drv_remove;
if (sdrv->shutdown)
sdrv->driver.shutdown = spi_drv_shutdown;
return driver_register(&sdrv->driver);
}
EXPORT_SYMBOL_GPL(spi_register_driver);
/*-------------------------------------------------------------------------*/
/* SPI devices should normally not be created by SPI device drivers; that
* would make them board-specific. Similarly with SPI master drivers.
* Device registration normally goes into like arch/.../mach.../board-YYY.c
* with other readonly (flashable) information about mainboard devices.
*/
struct boardinfo {
struct list_head list;
struct spi_board_info board_info;
};
static LIST_HEAD(board_list);
static LIST_HEAD(spi_master_list);
/*
* Used to protect add/del opertion for board_info list and
* spi_master list, and their matching process
*/
static DEFINE_MUTEX(board_lock);
/**
* spi_alloc_device - Allocate a new SPI device
* @master: Controller to which device is connected
* Context: can sleep
*
* Allows a driver to allocate and initialize a spi_device without
* registering it immediately. This allows a driver to directly
* fill the spi_device with device parameters before calling
* spi_add_device() on it.
*
* Caller is responsible to call spi_add_device() on the returned
* spi_device structure to add it to the SPI master. If the caller
* needs to discard the spi_device without adding it, then it should
* call spi_dev_put() on it.
*
* Returns a pointer to the new device, or NULL.
*/
struct spi_device *spi_alloc_device(struct spi_master *master)
{
struct spi_device *spi;
struct device *dev = master->dev.parent;
if (!spi_master_get(master))
return NULL;
spi = kzalloc(sizeof *spi, GFP_KERNEL);
if (!spi) {
dev_err(dev, "cannot alloc spi_device\n");
spi_master_put(master);
return NULL;
}
spi->master = master;
spi->dev.parent = &master->dev;
spi->dev.bus = &spi_bus_type;
spi->dev.release = spidev_release;
device_initialize(&spi->dev);
return spi;
}
EXPORT_SYMBOL_GPL(spi_alloc_device);
/**
* spi_add_device - Add spi_device allocated with spi_alloc_device
* @spi: spi_device to register
*
* Companion function to spi_alloc_device. Devices allocated with
* spi_alloc_device can be added onto the spi bus with this function.
*
* Returns 0 on success; negative errno on failure
*/
int spi_add_device(struct spi_device *spi)
{
static DEFINE_MUTEX(spi_add_lock);
struct device *dev = spi->master->dev.parent;
struct device *d;
int status;
/* Chipselects are numbered 0..max; validate. */
if (spi->chip_select >= spi->master->num_chipselect) {
dev_err(dev, "cs%d >= max %d\n",
spi->chip_select,
spi->master->num_chipselect);
return -EINVAL;
}
/* Set the bus ID string */
dev_set_name(&spi->dev, "%s.%u", dev_name(&spi->master->dev),
spi->chip_select);
/* We need to make sure there's no other device with this
* chipselect **BEFORE** we call setup(), else we'll trash
* its configuration. Lock against concurrent add() calls.
*/
mutex_lock(&spi_add_lock);
d = bus_find_device_by_name(&spi_bus_type, NULL, dev_name(&spi->dev));
if (d != NULL) {
dev_err(dev, "chipselect %d already in use\n",
spi->chip_select);
put_device(d);
status = -EBUSY;
goto done;
}
/* Drivers may modify this initial i/o setup, but will
* normally rely on the device being setup. Devices
* using SPI_CS_HIGH can't coexist well otherwise...
*/
status = spi_setup(spi);
if (status < 0) {
dev_err(dev, "can't setup %s, status %d\n",
dev_name(&spi->dev), status);
goto done;
}
/* Device may be bound to an active driver when this returns */
status = device_add(&spi->dev);
if (status < 0)
dev_err(dev, "can't add %s, status %d\n",
dev_name(&spi->dev), status);
else
dev_dbg(dev, "registered child %s\n", dev_name(&spi->dev));
done:
mutex_unlock(&spi_add_lock);
return status;
}
EXPORT_SYMBOL_GPL(spi_add_device);
/**
* spi_new_device - instantiate one new SPI device
* @master: Controller to which device is connected
* @chip: Describes the SPI device
* Context: can sleep
*
* On typical mainboards, this is purely internal; and it's not needed
* after board init creates the hard-wired devices. Some development
* platforms may not be able to use spi_register_board_info though, and
* this is exported so that for example a USB or parport based adapter
* driver could add devices (which it would learn about out-of-band).
*
* Returns the new device, or NULL.
*/
struct spi_device *spi_new_device(struct spi_master *master,
struct spi_board_info *chip)
{
struct spi_device *proxy;
int status;
/* NOTE: caller did any chip->bus_num checks necessary.
*
* Also, unless we change the return value convention to use
* error-or-pointer (not NULL-or-pointer), troubleshootability
* suggests syslogged diagnostics are best here (ugh).
*/
proxy = spi_alloc_device(master);
if (!proxy)
return NULL;
WARN_ON(strlen(chip->modalias) >= sizeof(proxy->modalias));
proxy->chip_select = chip->chip_select;
proxy->max_speed_hz = chip->max_speed_hz;
proxy->mode = chip->mode;
proxy->irq = chip->irq;
strlcpy(proxy->modalias, chip->modalias, sizeof(proxy->modalias));
proxy->dev.platform_data = (void *) chip->platform_data;
proxy->controller_data = chip->controller_data;
proxy->controller_state = NULL;
status = spi_add_device(proxy);
if (status < 0) {
spi_dev_put(proxy);
return NULL;
}
return proxy;
}
EXPORT_SYMBOL_GPL(spi_new_device);
static void spi_match_master_to_boardinfo(struct spi_master *master,
struct spi_board_info *bi)
{
struct spi_device *dev;
if (master->bus_num != bi->bus_num)
return;
dev = spi_new_device(master, bi);
if (!dev)
dev_err(master->dev.parent, "can't create new device for %s\n",
bi->modalias);
}
/**
* spi_register_board_info - register SPI devices for a given board
* @info: array of chip descriptors
* @n: how many descriptors are provided
* Context: can sleep
*
* Board-specific early init code calls this (probably during arch_initcall)
* with segments of the SPI device table. Any device nodes are created later,
* after the relevant parent SPI controller (bus_num) is defined. We keep
* this table of devices forever, so that reloading a controller driver will
* not make Linux forget about these hard-wired devices.
*
* Other code can also call this, e.g. a particular add-on board might provide
* SPI devices through its expansion connector, so code initializing that board
* would naturally declare its SPI devices.
*
* The board info passed can safely be __initdata ... but be careful of
* any embedded pointers (platform_data, etc), they're copied as-is.
*/
int __init
spi_register_board_info(struct spi_board_info const *info, unsigned n)
{
struct boardinfo *bi;
int i;
bi = kzalloc(n * sizeof(*bi), GFP_KERNEL);
if (!bi)
return -ENOMEM;
for (i = 0; i < n; i++, bi++, info++) {
struct spi_master *master;
memcpy(&bi->board_info, info, sizeof(*info));
mutex_lock(&board_lock);
list_add_tail(&bi->list, &board_list);
list_for_each_entry(master, &spi_master_list, list)
spi_match_master_to_boardinfo(master, &bi->board_info);
mutex_unlock(&board_lock);
}
return 0;
}
/*-------------------------------------------------------------------------*/
static void spi_master_release(struct device *dev)
{
struct spi_master *master;
master = container_of(dev, struct spi_master, dev);
kfree(master);
}
static struct class spi_master_class = {
.name = "spi_master",
.owner = THIS_MODULE,
.dev_release = spi_master_release,
};
/**
* spi_alloc_master - allocate SPI master controller
* @dev: the controller, possibly using the platform_bus
* @size: how much zeroed driver-private data to allocate; the pointer to this
* memory is in the driver_data field of the returned device,
* accessible with spi_master_get_devdata().
* Context: can sleep
*
* This call is used only by SPI master controller drivers, which are the
* only ones directly touching chip registers. It's how they allocate
* an spi_master structure, prior to calling spi_register_master().
*
* This must be called from context that can sleep. It returns the SPI
* master structure on success, else NULL.
*
* The caller is responsible for assigning the bus number and initializing
* the master's methods before calling spi_register_master(); and (after errors
* adding the device) calling spi_master_put() to prevent a memory leak.
*/
struct spi_master *spi_alloc_master(struct device *dev, unsigned size)
{
struct spi_master *master;
if (!dev)
return NULL;
master = kzalloc(size + sizeof *master, GFP_KERNEL);
if (!master)
return NULL;
device_initialize(&master->dev);
master->dev.class = &spi_master_class;
master->dev.parent = get_device(dev);
spi_master_set_devdata(master, &master[1]);
return master;
}
EXPORT_SYMBOL_GPL(spi_alloc_master);
/**
* spi_register_master - register SPI master controller
* @master: initialized master, originally from spi_alloc_master()
* Context: can sleep
*
* SPI master controllers connect to their drivers using some non-SPI bus,
* such as the platform bus. The final stage of probe() in that code
* includes calling spi_register_master() to hook up to this SPI bus glue.
*
* SPI controllers use board specific (often SOC specific) bus numbers,
* and board-specific addressing for SPI devices combines those numbers
* with chip select numbers. Since SPI does not directly support dynamic
* device identification, boards need configuration tables telling which
* chip is at which address.
*
* This must be called from context that can sleep. It returns zero on
* success, else a negative error code (dropping the master's refcount).
* After a successful return, the caller is responsible for calling
* spi_unregister_master().
*/
int spi_register_master(struct spi_master *master)
{
static atomic_t dyn_bus_id = ATOMIC_INIT((1<<15) - 1);
struct device *dev = master->dev.parent;
struct boardinfo *bi;
int status = -ENODEV;
int dynamic = 0;
if (!dev)
return -ENODEV;
/* even if it's just one always-selected device, there must
* be at least one chipselect
*/
if (master->num_chipselect == 0)
return -EINVAL;
/* convention: dynamically assigned bus IDs count down from the max */
if (master->bus_num < 0) {
/* FIXME switch to an IDR based scheme, something like
* I2C now uses, so we can't run out of "dynamic" IDs
*/
master->bus_num = atomic_dec_return(&dyn_bus_id);
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.
*/
dev_set_name(&master->dev, "spi%u", master->bus_num);
status = device_add(&master->dev);
if (status < 0)
goto done;
dev_dbg(dev, "registered master %s%s\n", dev_name(&master->dev),
dynamic ? " (dynamic)" : "");
mutex_lock(&board_lock);
list_add_tail(&master->list, &spi_master_list);
list_for_each_entry(bi, &board_list, list)
spi_match_master_to_boardinfo(master, &bi->board_info);
mutex_unlock(&board_lock);
status = 0;
/* Register devices from the device tree */
of_register_spi_devices(master);
done:
return status;
}
EXPORT_SYMBOL_GPL(spi_register_master);
static int __unregister(struct device *dev, void *null)
{
spi_unregister_device(to_spi_device(dev));
return 0;
}
/**
* spi_unregister_master - unregister SPI master controller
* @master: the master being unregistered
* Context: can sleep
*
* This call is used only by SPI master controller drivers, which are the
* only ones directly touching chip registers.
*
* This must be called from context that can sleep.
*/
void spi_unregister_master(struct spi_master *master)
{
int dummy;
mutex_lock(&board_lock);
list_del(&master->list);
mutex_unlock(&board_lock);
dummy = device_for_each_child(&master->dev, NULL, __unregister);
device_unregister(&master->dev);
}
EXPORT_SYMBOL_GPL(spi_unregister_master);
static int __spi_master_match(struct device *dev, void *data)
{
struct spi_master *m;
u16 *bus_num = data;
m = container_of(dev, struct spi_master, dev);
return m->bus_num == *bus_num;
}
/**
* spi_busnum_to_master - look up master associated with bus_num
* @bus_num: the master's bus number
* Context: can sleep
*
* This call may be used with devices that are registered after
* arch init time. It returns a refcounted pointer to the relevant
* spi_master (which the caller must release), or NULL if there is
* no such master registered.
*/
struct spi_master *spi_busnum_to_master(u16 bus_num)
{
struct device *dev;
struct spi_master *master = NULL;
dev = class_find_device(&spi_master_class, NULL, &bus_num,
__spi_master_match);
if (dev)
master = container_of(dev, struct spi_master, dev);
/* reference got in class_find_device */
return master;
}
EXPORT_SYMBOL_GPL(spi_busnum_to_master);
/*-------------------------------------------------------------------------*/
/* Core methods for SPI master protocol drivers. Some of the
* other core methods are currently defined as inline functions.
*/
/**
* spi_setup - setup SPI mode and clock rate
* @spi: the device whose settings are being modified
* Context: can sleep, and no requests are queued to the device
*
* SPI protocol drivers may need to update the transfer mode if the
* device doesn't work with its default. They may likewise need
* to update clock rates or word sizes from initial values. This function
* changes those settings, and must be called from a context that can sleep.
* Except for SPI_CS_HIGH, which takes effect immediately, the changes take
* effect the next time the device is selected and data is transferred to
* or from it. When this function returns, the spi device is deselected.
*
* Note that this call will fail if the protocol driver specifies an option
* that the underlying controller or its driver does not support. For
* example, not all hardware supports wire transfers using nine bit words,
* LSB-first wire encoding, or active-high chipselects.
*/
int spi_setup(struct spi_device *spi)
{
unsigned bad_bits;
int status;
/* help drivers fail *cleanly* when they need options
* that aren't supported with their current master
*/
bad_bits = spi->mode & ~spi->master->mode_bits;
if (bad_bits) {
dev_err(&spi->dev, "setup: unsupported mode bits %x\n",
bad_bits);
return -EINVAL;
}
if (!spi->bits_per_word)
spi->bits_per_word = 8;
status = spi->master->setup(spi);
dev_dbg(&spi->dev, "setup mode %d, %s%s%s%s"
"%u bits/w, %u Hz max --> %d\n",
(int) (spi->mode & (SPI_CPOL | SPI_CPHA)),
(spi->mode & SPI_CS_HIGH) ? "cs_high, " : "",
(spi->mode & SPI_LSB_FIRST) ? "lsb, " : "",
(spi->mode & SPI_3WIRE) ? "3wire, " : "",
(spi->mode & SPI_LOOP) ? "loopback, " : "",
spi->bits_per_word, spi->max_speed_hz,
status);
return status;
}
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
* @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(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);
if (master->bus_lock_flag)
ret = -EBUSY;
else
ret = __spi_async(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);
/*-------------------------------------------------------------------------*/
/* Utility methods for SPI master protocol drivers, layered on
* top of the core. Some other utility methods are defined as
* inline functions.
*/
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
* @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.
*
* Note that the SPI device's chip select is active during the message,
* and then is normally disabled between messages. Drivers for some
* frequently-used devices may want to minimize costs of selecting a chip,
* by leaving it selected in anticipation that the next message will go
* to the same chip. (That may increase power usage.)
*
* Also, the caller is guaranteeing that the memory associated with the
* message will not be freed before this call returns.
*
* It returns zero on success, else a negative error code.
*/
int spi_sync(struct spi_device *spi, struct spi_message *message)
{
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 preceded 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)
static u8 *buf;
/**
* spi_write_then_read - SPI synchronous write followed by read
* @spi: device with which data will be exchanged
* @txbuf: data to be written (need not be dma-safe)
* @n_tx: size of txbuf, in bytes
* @rxbuf: buffer into which data will be read (need not be dma-safe)
* @n_rx: size of rxbuf, in bytes
* Context: can sleep
*
* This performs a half duplex MicroWire style transaction with the
* device, sending txbuf and then reading rxbuf. The return value
* is zero for success, else a negative errno status code.
* This call may only be used from a context that may sleep.
*
* Parameters to this routine are always copied using a small buffer;
* portable code should never use this for more than 32 bytes.
* Performance-sensitive or bulk transfer code should instead use
* spi_{async,sync}() calls with dma-safe buffers.
*/
int spi_write_then_read(struct spi_device *spi,
const void *txbuf, unsigned n_tx,
void *rxbuf, unsigned n_rx)
{
static DEFINE_MUTEX(lock);
int status;
struct spi_message message;
struct spi_transfer x[2];
u8 *local_buf;
/* Use preallocated DMA-safe buffer. We can't avoid copying here,
* (as a pure convenience thing), but we can keep heap costs
* out of the hot path ...
*/
if ((n_tx + n_rx) > SPI_BUFSIZ)
return -EINVAL;
spi_message_init(&message);
memset(x, 0, sizeof x);
if (n_tx) {
x[0].len = n_tx;
spi_message_add_tail(&x[0], &message);
}
if (n_rx) {
x[1].len = n_rx;
spi_message_add_tail(&x[1], &message);
}
/* ... unless someone else is using the pre-allocated buffer */
if (!mutex_trylock(&lock)) {
local_buf = kmalloc(SPI_BUFSIZ, GFP_KERNEL);
if (!local_buf)
return -ENOMEM;
} else
local_buf = buf;
memcpy(local_buf, txbuf, n_tx);
x[0].tx_buf = local_buf;
x[1].rx_buf = local_buf + n_tx;
/* do the i/o */
status = spi_sync(spi, &message);
if (status == 0)
memcpy(rxbuf, x[1].rx_buf, n_rx);
if (x[0].tx_buf == buf)
mutex_unlock(&lock);
else
kfree(local_buf);
return status;
}
EXPORT_SYMBOL_GPL(spi_write_then_read);
/*-------------------------------------------------------------------------*/
static int __init spi_init(void)
{
int status;
buf = kmalloc(SPI_BUFSIZ, GFP_KERNEL);
if (!buf) {
status = -ENOMEM;
goto err0;
}
status = bus_register(&spi_bus_type);
if (status < 0)
goto err1;
status = class_register(&spi_master_class);
if (status < 0)
goto err2;
return 0;
err2:
bus_unregister(&spi_bus_type);
err1:
kfree(buf);
buf = NULL;
err0:
return status;
}
/* board_info is normally registered in arch_initcall(),
* but even essential drivers wait till later
*
* REVISIT only boardinfo really needs static linking. the rest (device and
* driver registration) _could_ be dynamically linked (modular) ... costs
* include needing to have boardinfo data structures be much more public.
*/
postcore_initcall(spi_init);