| /* |
| * 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/slab.h> |
| #include <linux/mod_devicetable.h> |
| #include <linux/spi/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); |
| |
| 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; |
| done: |
| return status; |
| } |
| EXPORT_SYMBOL_GPL(spi_register_master); |
| |
| |
| static int __unregister(struct device *dev, void *master_dev) |
| { |
| /* note: before about 2.6.14-rc1 this would corrupt memory: */ |
| if (dev != master_dev) |
| 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.parent, &master->dev, |
| __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); |
| |