// SPDX-License-Identifier: GPL-2.0-or-later /* * Simple synchronous userspace interface to SPI devices * * Copyright (C) 2006 SWAPP * Andrea Paterniani <[email protected]> * Copyright (C) 2007 David Brownell (simplification, cleanup) */ #include <linux/init.h> #include <linux/ioctl.h> #include <linux/fs.h> #include <linux/device.h> #include <linux/err.h> #include <linux/list.h> #include <linux/errno.h> #include <linux/mod_devicetable.h> #include <linux/module.h> #include <linux/mutex.h> #include <linux/property.h> #include <linux/slab.h> #include <linux/compat.h> #include <linux/spi/spi.h> #include <linux/spi/spidev.h> #include <linux/uaccess.h> /* * This supports access to SPI devices using normal userspace I/O calls. * Note that while traditional UNIX/POSIX I/O semantics are half duplex, * and often mask message boundaries, full SPI support requires full duplex * transfers. There are several kinds of internal message boundaries to * handle chipselect management and other protocol options. * * SPI has a character major number assigned. We allocate minor numbers * dynamically using a bitmask. You must use hotplug tools, such as udev * (or mdev with busybox) to create and destroy the /dev/spidevB.C device * nodes, since there is no fixed association of minor numbers with any * particular SPI bus or device. */ #define SPIDEV_MAJOR … #define N_SPI_MINORS … static DECLARE_BITMAP(minors, N_SPI_MINORS); static_assert(…); /* Bit masks for spi_device.mode management. Note that incorrect * settings for some settings can cause *lots* of trouble for other * devices on a shared bus: * * - CS_HIGH ... this device will be active when it shouldn't be * - 3WIRE ... when active, it won't behave as it should * - NO_CS ... there will be no explicit message boundaries; this * is completely incompatible with the shared bus model * - READY ... transfers may proceed when they shouldn't. * * REVISIT should changing those flags be privileged? */ #define SPI_MODE_MASK … struct spidev_data { … }; static LIST_HEAD(device_list); static DEFINE_MUTEX(device_list_lock); static unsigned bufsiz = …; module_param(bufsiz, uint, S_IRUGO); MODULE_PARM_DESC(…) …; /*-------------------------------------------------------------------------*/ static ssize_t spidev_sync_unlocked(struct spi_device *spi, struct spi_message *message) { … } static ssize_t spidev_sync(struct spidev_data *spidev, struct spi_message *message) { … } static inline ssize_t spidev_sync_write(struct spidev_data *spidev, size_t len) { … } static inline ssize_t spidev_sync_read(struct spidev_data *spidev, size_t len) { … } /*-------------------------------------------------------------------------*/ /* Read-only message with current device setup */ static ssize_t spidev_read(struct file *filp, char __user *buf, size_t count, loff_t *f_pos) { … } /* Write-only message with current device setup */ static ssize_t spidev_write(struct file *filp, const char __user *buf, size_t count, loff_t *f_pos) { … } static int spidev_message(struct spidev_data *spidev, struct spi_ioc_transfer *u_xfers, unsigned n_xfers) { … } static struct spi_ioc_transfer * spidev_get_ioc_message(unsigned int cmd, struct spi_ioc_transfer __user *u_ioc, unsigned *n_ioc) { … } static long spidev_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) { … } #ifdef CONFIG_COMPAT static long spidev_compat_ioc_message(struct file *filp, unsigned int cmd, unsigned long arg) { … } static long spidev_compat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) { … } #else #define spidev_compat_ioctl … #endif /* CONFIG_COMPAT */ static int spidev_open(struct inode *inode, struct file *filp) { … } static int spidev_release(struct inode *inode, struct file *filp) { … } static const struct file_operations spidev_fops = …; /*-------------------------------------------------------------------------*/ /* The main reason to have this class is to make mdev/udev create the * /dev/spidevB.C character device nodes exposing our userspace API. * It also simplifies memory management. */ static const struct class spidev_class = …; static const struct spi_device_id spidev_spi_ids[] = …; MODULE_DEVICE_TABLE(spi, spidev_spi_ids); /* * spidev should never be referenced in DT without a specific compatible string, * it is a Linux implementation thing rather than a description of the hardware. */ static int spidev_of_check(struct device *dev) { … } static const struct of_device_id spidev_dt_ids[] = …; MODULE_DEVICE_TABLE(of, spidev_dt_ids); /* Dummy SPI devices not to be used in production systems */ static int spidev_acpi_check(struct device *dev) { … } static const struct acpi_device_id spidev_acpi_ids[] = …; MODULE_DEVICE_TABLE(acpi, spidev_acpi_ids); /*-------------------------------------------------------------------------*/ static int spidev_probe(struct spi_device *spi) { … } static void spidev_remove(struct spi_device *spi) { … } static struct spi_driver spidev_spi_driver = …; /*-------------------------------------------------------------------------*/ static int __init spidev_init(void) { … } module_init(…) …; static void __exit spidev_exit(void) { … } module_exit(spidev_exit); MODULE_AUTHOR(…) …; MODULE_DESCRIPTION(…) …; MODULE_LICENSE(…) …; MODULE_ALIAS(…) …;
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