spi.c

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/*
 * 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)