// SPDX-License-Identifier: GPL-2.0-only /* * CMOS/NV-RAM driver for Linux * * Copyright (C) 1997 Roman Hodek <[email protected]> * idea by and with help from Richard Jelinek <[email protected]> * Portions copyright (c) 2001,2002 Sun Microsystems ([email protected]) * * This driver allows you to access the contents of the non-volatile memory in * the mc146818rtc.h real-time clock. This chip is built into all PCs and into * many Atari machines. In the former it's called "CMOS-RAM", in the latter * "NVRAM" (NV stands for non-volatile). * * The data are supplied as a (seekable) character device, /dev/nvram. The * size of this file is dependent on the controller. The usual size is 114, * the number of freely available bytes in the memory (i.e., not used by the * RTC itself). * * Checksums over the NVRAM contents are managed by this driver. In case of a * bad checksum, reads and writes return -EIO. The checksum can be initialized * to a sane state either by ioctl(NVRAM_INIT) (clear whole NVRAM) or * ioctl(NVRAM_SETCKS) (doesn't change contents, just makes checksum valid * again; use with care!) * * 1.1 Cesar Barros: SMP locking fixes * added changelog * 1.2 Erik Gilling: Cobalt Networks support * Tim Hockin: general cleanup, Cobalt support * 1.3 Wim Van Sebroeck: convert PRINT_PROC to seq_file */ #define NVRAM_VERSION … #include <linux/module.h> #include <linux/nvram.h> #include <linux/types.h> #include <linux/errno.h> #include <linux/miscdevice.h> #include <linux/ioport.h> #include <linux/fcntl.h> #include <linux/mc146818rtc.h> #include <linux/init.h> #include <linux/proc_fs.h> #include <linux/seq_file.h> #include <linux/slab.h> #include <linux/spinlock.h> #include <linux/io.h> #include <linux/uaccess.h> #include <linux/mutex.h> #include <linux/pagemap.h> #ifdef CONFIG_PPC #include <asm/nvram.h> #endif static DEFINE_MUTEX(nvram_mutex); static DEFINE_SPINLOCK(nvram_state_lock); static int nvram_open_cnt; /* #times opened */ static int nvram_open_mode; /* special open modes */ static ssize_t nvram_size; #define NVRAM_WRITE … #define NVRAM_EXCL … #ifdef CONFIG_X86 /* * These functions are provided to be called internally or by other parts of * the kernel. It's up to the caller to ensure correct checksum before reading * or after writing (needs to be done only once). * * It is worth noting that these functions all access bytes of general * purpose memory in the NVRAM - that is to say, they all add the * NVRAM_FIRST_BYTE offset. Pass them offsets into NVRAM as if you did not * know about the RTC cruft. */ #define NVRAM_BYTES … /* Note that *all* calls to CMOS_READ and CMOS_WRITE must be done with * rtc_lock held. Due to the index-port/data-port design of the RTC, we * don't want two different things trying to get to it at once. (e.g. the * periodic 11 min sync from kernel/time/ntp.c vs. this driver.) */ static unsigned char __nvram_read_byte(int i) { … } static unsigned char pc_nvram_read_byte(int i) { … } /* This races nicely with trying to read with checksum checking (nvram_read) */ static void __nvram_write_byte(unsigned char c, int i) { … } static void pc_nvram_write_byte(unsigned char c, int i) { … } /* On PCs, the checksum is built only over bytes 2..31 */ #define PC_CKS_RANGE_START … #define PC_CKS_RANGE_END … #define PC_CKS_LOC … static int __nvram_check_checksum(void) { … } static void __nvram_set_checksum(void) { … } static long pc_nvram_set_checksum(void) { … } static long pc_nvram_initialize(void) { … } static ssize_t pc_nvram_get_size(void) { … } static ssize_t pc_nvram_read(char *buf, size_t count, loff_t *ppos) { … } static ssize_t pc_nvram_write(char *buf, size_t count, loff_t *ppos) { … } const struct nvram_ops arch_nvram_ops = …; EXPORT_SYMBOL(…); #endif /* CONFIG_X86 */ /* * The are the file operation function for user access to /dev/nvram */ static loff_t nvram_misc_llseek(struct file *file, loff_t offset, int origin) { … } static ssize_t nvram_misc_read(struct file *file, char __user *buf, size_t count, loff_t *ppos) { … } static ssize_t nvram_misc_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos) { … } static long nvram_misc_ioctl(struct file *file, unsigned int cmd, unsigned long arg) { … } static int nvram_misc_open(struct inode *inode, struct file *file) { … } static int nvram_misc_release(struct inode *inode, struct file *file) { … } #if defined(CONFIG_X86) && defined(CONFIG_PROC_FS) static const char * const floppy_types[] = …; static const char * const gfx_types[] = …; static void pc_nvram_proc_read(unsigned char *nvram, struct seq_file *seq, void *offset) { … } static int nvram_proc_read(struct seq_file *seq, void *offset) { … } #endif /* CONFIG_X86 && CONFIG_PROC_FS */ static const struct file_operations nvram_misc_fops = …; static struct miscdevice nvram_misc = …; static int __init nvram_module_init(void) { … } static void __exit nvram_module_exit(void) { … } module_init(…) …; module_exit(nvram_module_exit); MODULE_DESCRIPTION(…) …; MODULE_LICENSE(…) …; MODULE_ALIAS_MISCDEV(…); MODULE_ALIAS(…) …;
Codebase Browser
linux