/* * 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/autoconf.h> #include <linux/kernel.h> #include <linux/device.h> #include <linux/init.h> #include <linux/cache.h> #include <linux/mutex.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(dev); } static ssize_t modalias_show(struct device *dev, struct device_attribute *a, char *buf) { const struct spi_device *spi = to_spi_device(dev); return snprintf(buf, BUS_ID_SIZE + 1, "%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 int spi_match_device(struct device *dev, struct device_driver *drv) { const struct spi_device *spi = to_spi_device(dev); return strncmp(spi->modalias, drv->name, BUS_ID_SIZE) == 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", spi->modalias); return 0; } #ifdef CONFIG_PM /* * NOTE: the suspend() method for an spi_master controller driver * should verify that all its child devices are marked as suspended; * suspend requests delivered through sysfs power/state files don't * enforce such constraints. */ static int spi_suspend(struct device *dev, pm_message_t message) { int value; struct spi_driver *drv = to_spi_driver(dev->driver); if (!drv || !drv->suspend) return 0; /* suspend will stop irqs and dma; no more i/o */ value = drv->suspend(to_spi_device(dev), message); if (value == 0) dev->power.power_state = message; return value; } static int spi_resume(struct device *dev) { int value; struct spi_driver *drv = to_spi_driver(dev->driver); if (!drv || !drv->resume) return 0; /* resume may restart the i/o queue */ value = drv->resume(to_spi_device(dev)); if (value == 0) dev->power.power_state = PMSG_ON; 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_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; struct device *dev = master->dev.parent; 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). */ /* Chipselects are numbered 0..max; validate. */ if (chip->chip_select >= master->num_chipselect) { dev_err(dev, "cs%d > max %d\n", chip->chip_select, master->num_chipselect); return NULL; } if (!spi_master_get(master)) return NULL; proxy = kzalloc(sizeof *proxy, GFP_KERNEL); if (!proxy) { dev_err(dev, "can't alloc dev for cs%d\n", chip->chip_select); goto fail; } proxy->master = master; proxy->chip_select = chip->chip_select; proxy->max_speed_hz = chip->max_speed_hz; proxy->mode = chip->mode; proxy->irq = chip->irq; proxy->modalias = chip->modalias; snprintf(proxy->dev.bus_id, sizeof proxy->dev.bus_id, "%s.%u", master->dev.bus_id, chip->chip_select); proxy->dev.parent = dev; proxy->dev.bus = &spi_bus_type; proxy->dev.platform_data = (void *) chip->platform_data; proxy->controller_data = chip->controller_data; proxy->controller_state = NULL; proxy->dev.release = spidev_release; /* drivers may modify this initial i/o setup */ status = master->setup(proxy); if (status < 0) { dev_err(dev, "can't %s %s, status %d\n", "setup", proxy->dev.bus_id, status); goto fail; } /* driver core catches callers that misbehave by defining * devices that already exist. */ status = device_register(&proxy->dev); if (status < 0) { dev_err(dev, "can't %s %s, status %d\n", "add", proxy->dev.bus_id, status); goto fail; } dev_dbg(dev, "registered child %s\n", proxy->dev.bus_id); return proxy; fail: spi_master_put(master); kfree(proxy); return NULL; } 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; } /* register the device, then userspace will see it. * registration fails if the bus ID is in use. */ snprintf(master->dev.bus_id, sizeof master->dev.bus_id, "spi%u", master->bus_num); status = device_add(&master->dev); if (status < 0) goto done; dev_dbg(dev, "registered master %s%s\n", master->dev.bus_id, 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 *unused) { /* note: before about 2.6.14-rc1 this would corrupt memory: */ 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, NULL, __unregister); device_unregister(&master->dev); } EXPORT_SYMBOL_GPL(spi_unregister_master); /** * 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; struct spi_master *m; down(&spi_master_class.sem); list_for_each_entry(dev, &spi_master_class.children, node) { m = container_of(dev, struct spi_master, dev); if (m->bus_num == bus_num) { master = spi_master_get(m); break; } } up(&spi_master_class.sem); return master; } EXPORT_SYMBOL_GPL(spi_busnum_to_master); /*-------------------------------------------------------------------------*/ static void spi_complete(void *arg) { complete(arg); } /** * 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. * * The return value is a negative error code if the message could not be * submitted, else zero. When the value is zero, then message->status is * also defined; it's the completion code for the transfer, either zero * or a negative error code from the controller driver. */ int spi_sync(struct spi_device *spi, struct spi_message *message) { DECLARE_COMPLETION_ONSTACK(done); int status; message->complete = spi_complete; message->context = &done; status = spi_async(spi, message); if (status == 0) wait_for_completion(&done); message->context = NULL; return status; } EXPORT_SYMBOL_GPL(spi_sync); /* 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 * @n_rx: size of rxbuf, in bytes (need not be dma-safe) * 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 DECLARE_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 (down_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); status = message.status; } if (x[0].tx_buf == buf) up(&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. */ subsys_initcall(spi_init);