/* * 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> 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 = 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 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);