diff options
Diffstat (limited to 'drivers/spi/spi.c')
| -rw-r--r-- | drivers/spi/spi.c | 1061 |
1 files changed, 1061 insertions, 0 deletions
diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c new file mode 100644 index 00000000..b5a78a1f --- /dev/null +++ b/drivers/spi/spi.c @@ -0,0 +1,1061 @@ +/* + * 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> + + +/* SPI bustype and spi_master class are registered after board init code + * provides the SPI device tables, ensuring that both are present by the + * time controller driver registration causes spi_devices to "enumerate". + */ +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 + +static int spi_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_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; +} + +#else +#define spi_suspend NULL +#define spi_resume NULL +#endif + +struct bus_type spi_bus_type = { + .name = "spi", + .dev_attrs = spi_dev_attrs, + .match = spi_match_device, + .uevent = spi_uevent, + .suspend = spi_suspend, + .resume = spi_resume, +}; +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; + unsigned n_board_info; + struct spi_board_info board_info[0]; +}; + +static LIST_HEAD(board_list); +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 = 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 %s %s, status %d\n", + "setup", 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 %s %s, status %d\n", + "add", 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); + +/** + * 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; + + bi = kmalloc(sizeof(*bi) + n * sizeof *info, GFP_KERNEL); + if (!bi) + return -ENOMEM; + bi->n_board_info = n; + memcpy(bi->board_info, info, n * sizeof *info); + + mutex_lock(&board_lock); + list_add_tail(&bi->list, &board_list); + mutex_unlock(&board_lock); + return 0; +} + +/* FIXME someone should add support for a __setup("spi", ...) that + * creates board info from kernel command lines + */ + +static void scan_boardinfo(struct spi_master *master) +{ + struct boardinfo *bi; + + mutex_lock(&board_lock); + list_for_each_entry(bi, &board_list, list) { + struct spi_board_info *chip = bi->board_info; + unsigned n; + + for (n = bi->n_board_info; n > 0; n--, chip++) { + if (chip->bus_num != master->bus_num) + continue; + /* NOTE: this relies on spi_new_device to + * issue diagnostics when given bogus inputs + */ + (void) spi_new_device(master, chip); + } + } + mutex_unlock(&board_lock); +} + +/*-------------------------------------------------------------------------*/ + +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; + 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)" : ""); + + /* populate children from any spi device tables */ + scan_boardinfo(master); + 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; + + 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_dbg(&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 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) + +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 u8 *txbuf, unsigned n_tx, + u8 *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); + |