mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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0ffa028505
I'd like to assign NULL to kfree()d members of a structure. I can't do that without ugly casting (see the PXA patch) when the structure pointed to is const-qualified. I don't really see a reason why the cleanup method isn't allowed to alter the object it should clean up. :-) No, I didn't test the PXA patch, but I verified that the NULL-assignment doesn't stop me from doing rmmod/insmodding my own spi_bitbang-based driver. Signed-off-by: Hans-Peter Nilsson <hp@axis.com> Signed-off-by: David Brownell <dbrownell@users.sourceforge.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
649 lines
18 KiB
C
649 lines
18 KiB
C
/*
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* spi.c - SPI init/core code
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*
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* Copyright (C) 2005 David Brownell
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#include <linux/autoconf.h>
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#include <linux/kernel.h>
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#include <linux/device.h>
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#include <linux/init.h>
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#include <linux/cache.h>
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#include <linux/spi/spi.h>
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/* SPI bustype and spi_master class are registered after board init code
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* provides the SPI device tables, ensuring that both are present by the
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* time controller driver registration causes spi_devices to "enumerate".
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*/
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static void spidev_release(struct device *dev)
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{
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struct spi_device *spi = to_spi_device(dev);
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/* spi masters may cleanup for released devices */
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if (spi->master->cleanup)
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spi->master->cleanup(spi);
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spi_master_put(spi->master);
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kfree(dev);
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}
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static ssize_t
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modalias_show(struct device *dev, struct device_attribute *a, char *buf)
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{
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const struct spi_device *spi = to_spi_device(dev);
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return snprintf(buf, BUS_ID_SIZE + 1, "%s\n", spi->modalias);
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}
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static struct device_attribute spi_dev_attrs[] = {
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__ATTR_RO(modalias),
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__ATTR_NULL,
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};
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/* modalias support makes "modprobe $MODALIAS" new-style hotplug work,
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* and the sysfs version makes coldplug work too.
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*/
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static int spi_match_device(struct device *dev, struct device_driver *drv)
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{
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const struct spi_device *spi = to_spi_device(dev);
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return strncmp(spi->modalias, drv->name, BUS_ID_SIZE) == 0;
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}
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static int spi_uevent(struct device *dev, char **envp, int num_envp,
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char *buffer, int buffer_size)
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{
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const struct spi_device *spi = to_spi_device(dev);
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envp[0] = buffer;
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snprintf(buffer, buffer_size, "MODALIAS=%s", spi->modalias);
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envp[1] = NULL;
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return 0;
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}
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#ifdef CONFIG_PM
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/*
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* NOTE: the suspend() method for an spi_master controller driver
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* should verify that all its child devices are marked as suspended;
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* suspend requests delivered through sysfs power/state files don't
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* enforce such constraints.
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*/
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static int spi_suspend(struct device *dev, pm_message_t message)
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{
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int value;
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struct spi_driver *drv = to_spi_driver(dev->driver);
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if (!drv || !drv->suspend)
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return 0;
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/* suspend will stop irqs and dma; no more i/o */
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value = drv->suspend(to_spi_device(dev), message);
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if (value == 0)
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dev->power.power_state = message;
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return value;
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}
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static int spi_resume(struct device *dev)
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{
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int value;
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struct spi_driver *drv = to_spi_driver(dev->driver);
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if (!drv || !drv->resume)
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return 0;
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/* resume may restart the i/o queue */
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value = drv->resume(to_spi_device(dev));
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if (value == 0)
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dev->power.power_state = PMSG_ON;
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return value;
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}
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#else
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#define spi_suspend NULL
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#define spi_resume NULL
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#endif
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struct bus_type spi_bus_type = {
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.name = "spi",
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.dev_attrs = spi_dev_attrs,
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.match = spi_match_device,
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.uevent = spi_uevent,
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.suspend = spi_suspend,
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.resume = spi_resume,
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};
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EXPORT_SYMBOL_GPL(spi_bus_type);
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static int spi_drv_probe(struct device *dev)
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{
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const struct spi_driver *sdrv = to_spi_driver(dev->driver);
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return sdrv->probe(to_spi_device(dev));
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}
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static int spi_drv_remove(struct device *dev)
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{
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const struct spi_driver *sdrv = to_spi_driver(dev->driver);
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return sdrv->remove(to_spi_device(dev));
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}
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static void spi_drv_shutdown(struct device *dev)
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{
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const struct spi_driver *sdrv = to_spi_driver(dev->driver);
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sdrv->shutdown(to_spi_device(dev));
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}
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int spi_register_driver(struct spi_driver *sdrv)
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{
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sdrv->driver.bus = &spi_bus_type;
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if (sdrv->probe)
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sdrv->driver.probe = spi_drv_probe;
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if (sdrv->remove)
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sdrv->driver.remove = spi_drv_remove;
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if (sdrv->shutdown)
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sdrv->driver.shutdown = spi_drv_shutdown;
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return driver_register(&sdrv->driver);
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}
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EXPORT_SYMBOL_GPL(spi_register_driver);
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/*-------------------------------------------------------------------------*/
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/* SPI devices should normally not be created by SPI device drivers; that
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* would make them board-specific. Similarly with SPI master drivers.
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* Device registration normally goes into like arch/.../mach.../board-YYY.c
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* with other readonly (flashable) information about mainboard devices.
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*/
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struct boardinfo {
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struct list_head list;
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unsigned n_board_info;
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struct spi_board_info board_info[0];
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};
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static LIST_HEAD(board_list);
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static DECLARE_MUTEX(board_lock);
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/* On typical mainboards, this is purely internal; and it's not needed
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* after board init creates the hard-wired devices. Some development
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* platforms may not be able to use spi_register_board_info though, and
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* this is exported so that for example a USB or parport based adapter
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* driver could add devices (which it would learn about out-of-band).
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*/
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struct spi_device *__init_or_module
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spi_new_device(struct spi_master *master, struct spi_board_info *chip)
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{
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struct spi_device *proxy;
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struct device *dev = master->cdev.dev;
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int status;
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/* NOTE: caller did any chip->bus_num checks necessary */
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if (!spi_master_get(master))
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return NULL;
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proxy = kzalloc(sizeof *proxy, GFP_KERNEL);
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if (!proxy) {
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dev_err(dev, "can't alloc dev for cs%d\n",
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chip->chip_select);
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goto fail;
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}
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proxy->master = master;
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proxy->chip_select = chip->chip_select;
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proxy->max_speed_hz = chip->max_speed_hz;
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proxy->mode = chip->mode;
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proxy->irq = chip->irq;
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proxy->modalias = chip->modalias;
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snprintf(proxy->dev.bus_id, sizeof proxy->dev.bus_id,
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"%s.%u", master->cdev.class_id,
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chip->chip_select);
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proxy->dev.parent = dev;
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proxy->dev.bus = &spi_bus_type;
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proxy->dev.platform_data = (void *) chip->platform_data;
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proxy->controller_data = chip->controller_data;
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proxy->controller_state = NULL;
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proxy->dev.release = spidev_release;
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/* drivers may modify this default i/o setup */
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status = master->setup(proxy);
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if (status < 0) {
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dev_dbg(dev, "can't %s %s, status %d\n",
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"setup", proxy->dev.bus_id, status);
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goto fail;
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}
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/* driver core catches callers that misbehave by defining
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* devices that already exist.
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*/
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status = device_register(&proxy->dev);
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if (status < 0) {
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dev_dbg(dev, "can't %s %s, status %d\n",
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"add", proxy->dev.bus_id, status);
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goto fail;
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}
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dev_dbg(dev, "registered child %s\n", proxy->dev.bus_id);
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return proxy;
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fail:
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spi_master_put(master);
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kfree(proxy);
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return NULL;
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}
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EXPORT_SYMBOL_GPL(spi_new_device);
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/*
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* Board-specific early init code calls this (probably during arch_initcall)
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* with segments of the SPI device table. Any device nodes are created later,
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* after the relevant parent SPI controller (bus_num) is defined. We keep
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* this table of devices forever, so that reloading a controller driver will
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* not make Linux forget about these hard-wired devices.
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*
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* Other code can also call this, e.g. a particular add-on board might provide
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* SPI devices through its expansion connector, so code initializing that board
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* would naturally declare its SPI devices.
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*
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* The board info passed can safely be __initdata ... but be careful of
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* any embedded pointers (platform_data, etc), they're copied as-is.
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*/
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int __init
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spi_register_board_info(struct spi_board_info const *info, unsigned n)
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{
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struct boardinfo *bi;
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bi = kmalloc(sizeof(*bi) + n * sizeof *info, GFP_KERNEL);
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if (!bi)
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return -ENOMEM;
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bi->n_board_info = n;
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memcpy(bi->board_info, info, n * sizeof *info);
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down(&board_lock);
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list_add_tail(&bi->list, &board_list);
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up(&board_lock);
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return 0;
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}
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/* FIXME someone should add support for a __setup("spi", ...) that
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* creates board info from kernel command lines
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*/
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static void __init_or_module
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scan_boardinfo(struct spi_master *master)
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{
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struct boardinfo *bi;
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struct device *dev = master->cdev.dev;
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down(&board_lock);
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list_for_each_entry(bi, &board_list, list) {
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struct spi_board_info *chip = bi->board_info;
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unsigned n;
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for (n = bi->n_board_info; n > 0; n--, chip++) {
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if (chip->bus_num != master->bus_num)
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continue;
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/* some controllers only have one chip, so they
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* might not use chipselects. otherwise, the
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* chipselects are numbered 0..max.
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*/
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if (chip->chip_select >= master->num_chipselect
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&& master->num_chipselect) {
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dev_dbg(dev, "cs%d > max %d\n",
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chip->chip_select,
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master->num_chipselect);
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continue;
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}
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(void) spi_new_device(master, chip);
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}
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}
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up(&board_lock);
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}
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/*-------------------------------------------------------------------------*/
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static void spi_master_release(struct class_device *cdev)
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{
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struct spi_master *master;
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master = container_of(cdev, struct spi_master, cdev);
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kfree(master);
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}
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static struct class spi_master_class = {
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.name = "spi_master",
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.owner = THIS_MODULE,
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.release = spi_master_release,
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};
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/**
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* spi_alloc_master - allocate SPI master controller
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* @dev: the controller, possibly using the platform_bus
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* @size: how much driver-private data to preallocate; the pointer to this
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* memory is in the class_data field of the returned class_device,
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* accessible with spi_master_get_devdata().
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*
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* This call is used only by SPI master controller drivers, which are the
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* only ones directly touching chip registers. It's how they allocate
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* an spi_master structure, prior to calling spi_register_master().
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*
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* This must be called from context that can sleep. It returns the SPI
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* master structure on success, else NULL.
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*
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* The caller is responsible for assigning the bus number and initializing
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* the master's methods before calling spi_register_master(); and (after errors
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* adding the device) calling spi_master_put() to prevent a memory leak.
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*/
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struct spi_master * __init_or_module
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spi_alloc_master(struct device *dev, unsigned size)
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{
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struct spi_master *master;
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if (!dev)
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return NULL;
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master = kzalloc(size + sizeof *master, GFP_KERNEL);
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if (!master)
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return NULL;
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class_device_initialize(&master->cdev);
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master->cdev.class = &spi_master_class;
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master->cdev.dev = get_device(dev);
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spi_master_set_devdata(master, &master[1]);
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return master;
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}
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EXPORT_SYMBOL_GPL(spi_alloc_master);
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/**
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* spi_register_master - register SPI master controller
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* @master: initialized master, originally from spi_alloc_master()
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*
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* SPI master controllers connect to their drivers using some non-SPI bus,
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* such as the platform bus. The final stage of probe() in that code
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* includes calling spi_register_master() to hook up to this SPI bus glue.
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*
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* SPI controllers use board specific (often SOC specific) bus numbers,
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* and board-specific addressing for SPI devices combines those numbers
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* with chip select numbers. Since SPI does not directly support dynamic
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* device identification, boards need configuration tables telling which
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* chip is at which address.
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*
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* This must be called from context that can sleep. It returns zero on
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* success, else a negative error code (dropping the master's refcount).
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* After a successful return, the caller is responsible for calling
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* spi_unregister_master().
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*/
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int __init_or_module
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spi_register_master(struct spi_master *master)
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{
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static atomic_t dyn_bus_id = ATOMIC_INIT((1<<16) - 1);
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struct device *dev = master->cdev.dev;
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int status = -ENODEV;
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int dynamic = 0;
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if (!dev)
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return -ENODEV;
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/* convention: dynamically assigned bus IDs count down from the max */
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if (master->bus_num < 0) {
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master->bus_num = atomic_dec_return(&dyn_bus_id);
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dynamic = 1;
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}
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/* register the device, then userspace will see it.
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* registration fails if the bus ID is in use.
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*/
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snprintf(master->cdev.class_id, sizeof master->cdev.class_id,
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"spi%u", master->bus_num);
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status = class_device_add(&master->cdev);
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if (status < 0)
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goto done;
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dev_dbg(dev, "registered master %s%s\n", master->cdev.class_id,
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dynamic ? " (dynamic)" : "");
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/* populate children from any spi device tables */
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scan_boardinfo(master);
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status = 0;
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done:
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return status;
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}
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EXPORT_SYMBOL_GPL(spi_register_master);
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static int __unregister(struct device *dev, void *unused)
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{
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/* note: before about 2.6.14-rc1 this would corrupt memory: */
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spi_unregister_device(to_spi_device(dev));
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return 0;
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}
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/**
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* spi_unregister_master - unregister SPI master controller
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* @master: the master being unregistered
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*
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* This call is used only by SPI master controller drivers, which are the
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* only ones directly touching chip registers.
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*
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* This must be called from context that can sleep.
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*/
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void spi_unregister_master(struct spi_master *master)
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{
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int dummy;
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dummy = device_for_each_child(master->cdev.dev, NULL, __unregister);
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class_device_unregister(&master->cdev);
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}
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EXPORT_SYMBOL_GPL(spi_unregister_master);
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/**
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* spi_busnum_to_master - look up master associated with bus_num
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* @bus_num: the master's bus number
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*
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* This call may be used with devices that are registered after
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* arch init time. It returns a refcounted pointer to the relevant
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* spi_master (which the caller must release), or NULL if there is
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* no such master registered.
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*/
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struct spi_master *spi_busnum_to_master(u16 bus_num)
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{
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struct class_device *cdev;
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struct spi_master *master = NULL;
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struct spi_master *m;
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down(&spi_master_class.sem);
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list_for_each_entry(cdev, &spi_master_class.children, node) {
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m = container_of(cdev, struct spi_master, cdev);
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if (m->bus_num == bus_num) {
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master = spi_master_get(m);
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break;
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}
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}
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up(&spi_master_class.sem);
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return master;
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}
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EXPORT_SYMBOL_GPL(spi_busnum_to_master);
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/*-------------------------------------------------------------------------*/
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static void spi_complete(void *arg)
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{
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complete(arg);
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}
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/**
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* spi_sync - blocking/synchronous SPI data transfers
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* @spi: device with which data will be exchanged
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* @message: describes the data transfers
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*
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* This call may only be used from a context that may sleep. The sleep
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* is non-interruptible, and has no timeout. Low-overhead controller
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* drivers may DMA directly into and out of the message buffers.
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*
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* Note that the SPI device's chip select is active during the message,
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* and then is normally disabled between messages. Drivers for some
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* frequently-used devices may want to minimize costs of selecting a chip,
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* by leaving it selected in anticipation that the next message will go
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* to the same chip. (That may increase power usage.)
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*
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* 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)
|
|
*
|
|
* 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;
|
|
* 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);
|
|
|