/* * Blackfin On-Chip OTP Memory Interface * * Copyright 2007-2009 Analog Devices Inc. * * Enter bugs at http://blackfin.uclinux.org/ * * Licensed under the GPL-2 or later. */ #include <linux/device.h> #include <linux/errno.h> #include <linux/fs.h> #include <linux/init.h> #include <linux/miscdevice.h> #include <linux/module.h> #include <linux/mutex.h> #include <linux/types.h> #include <mtd/mtd-abi.h> #include <asm/blackfin.h> #include <asm/bfrom.h> #include <asm/uaccess.h> #define stamp(fmt, args...) pr_debug("%s:%i: " fmt "\n", __func__, __LINE__, ## args) #define stampit() stamp("here i am") #define pr_init(fmt, args...) ({ static const __initconst char __fmt[] = fmt; printk(__fmt, ## args); }) #define DRIVER_NAME "bfin-otp" #define PFX DRIVER_NAME ": " static DEFINE_MUTEX(bfin_otp_lock); /** * bfin_otp_read - Read OTP pages * * All reads must be in half page chunks (half page == 64 bits). */ static ssize_t bfin_otp_read(struct file *file, char __user *buff, size_t count, loff_t *pos) { ssize_t bytes_done; u32 page, flags, ret; u64 content; stampit(); if (count % sizeof(u64)) return -EMSGSIZE; if (mutex_lock_interruptible(&bfin_otp_lock)) return -ERESTARTSYS; bytes_done = 0; page = *pos / (sizeof(u64) * 2); while (bytes_done < count) { flags = (*pos % (sizeof(u64) * 2) ? OTP_UPPER_HALF : OTP_LOWER_HALF); stamp("processing page %i (0x%x:%s)", page, flags, (flags & OTP_UPPER_HALF ? "upper" : "lower")); ret = bfrom_OtpRead(page, flags, &content); if (ret & OTP_MASTER_ERROR) { stamp("error from otp: 0x%x", ret); bytes_done = -EIO; break; } if (copy_to_user(buff + bytes_done, &content, sizeof(content))) { bytes_done = -EFAULT; break; } if (flags & OTP_UPPER_HALF) ++page; bytes_done += sizeof(content); *pos += sizeof(content); } mutex_unlock(&bfin_otp_lock); return bytes_done; } #ifdef CONFIG_BFIN_OTP_WRITE_ENABLE static bool allow_writes; /** * bfin_otp_init_timing - setup OTP timing parameters * * Required before doing any write operation. Algorithms from HRM. */ static u32 bfin_otp_init_timing(void) { u32 tp1, tp2, tp3, timing; tp1 = get_sclk() / 1000000; tp2 = (2 * get_sclk() / 10000000) << 8; tp3 = (0x1401) << 15; timing = tp1 | tp2 | tp3; if (bfrom_OtpCommand(OTP_INIT, timing)) return 0; return timing; } /** * bfin_otp_deinit_timing - set timings to only allow reads * * Should be called after all writes are done. */ static void bfin_otp_deinit_timing(u32 timing) { /* mask bits [31:15] so that any attempts to write fail */ bfrom_OtpCommand(OTP_CLOSE, 0); bfrom_OtpCommand(OTP_INIT, timing & ~(-1 << 15)); bfrom_OtpCommand(OTP_CLOSE, 0); } /** * bfin_otp_write - write OTP pages * * All writes must be in half page chunks (half page == 64 bits). */ static ssize_t bfin_otp_write(struct file *filp, const char __user *buff, size_t count, loff_t *pos) { ssize_t bytes_done; u32 timing, page, base_flags, flags, ret; u64 content; if (!allow_writes) return -EACCES; if (count % sizeof(u64)) return -EMSGSIZE; if (mutex_lock_interruptible(&bfin_otp_lock)) return -ERESTARTSYS; stampit(); timing = bfin_otp_init_timing(); if (timing == 0) { mutex_unlock(&bfin_otp_lock); return -EIO; } base_flags = OTP_CHECK_FOR_PREV_WRITE; bytes_done = 0; page = *pos / (sizeof(u64) * 2); while (bytes_done < count) { flags = base_flags | (*pos % (sizeof(u64) * 2) ? OTP_UPPER_HALF : OTP_LOWER_HALF); stamp("processing page %i (0x%x:%s) from %p", page, flags, (flags & OTP_UPPER_HALF ? "upper" : "lower"), buff + bytes_done); if (copy_from_user(&content, buff + bytes_done, sizeof(content))) { bytes_done = -EFAULT; break; } ret = bfrom_OtpWrite(page, flags, &content); if (ret & OTP_MASTER_ERROR) { stamp("error from otp: 0x%x", ret); bytes_done = -EIO; break; } if (flags & OTP_UPPER_HALF) ++page; bytes_done += sizeof(content); *pos += sizeof(content); } bfin_otp_deinit_timing(timing); mutex_unlock(&bfin_otp_lock); return bytes_done; } static long bfin_otp_ioctl(struct file *filp, unsigned cmd, unsigned long arg) { stampit(); switch (cmd) { case OTPLOCK: { u32 timing; int ret = -EIO; if (!allow_writes) return -EACCES; if (mutex_lock_interruptible(&bfin_otp_lock)) return -ERESTARTSYS; timing = bfin_otp_init_timing(); if (timing) { u32 otp_result = bfrom_OtpWrite(arg, OTP_LOCK, NULL); stamp("locking page %lu resulted in 0x%x", arg, otp_result); if (!(otp_result & OTP_MASTER_ERROR)) ret = 0; bfin_otp_deinit_timing(timing); } mutex_unlock(&bfin_otp_lock); return ret; } case MEMLOCK: allow_writes = false; return 0; case MEMUNLOCK: allow_writes = true; return 0; } return -EINVAL; } #else # define bfin_otp_write NULL # define bfin_otp_ioctl NULL #endif static const struct file_operations bfin_otp_fops = { .owner = THIS_MODULE, .unlocked_ioctl = bfin_otp_ioctl, .read = bfin_otp_read, .write = bfin_otp_write, .llseek = default_llseek, }; static struct miscdevice bfin_otp_misc_device = { .minor = MISC_DYNAMIC_MINOR, .name = DRIVER_NAME, .fops = &bfin_otp_fops, }; /** * bfin_otp_init - Initialize module * * Registers the device and notifier handler. Actual device * initialization is handled by bfin_otp_open(). */ static int __init bfin_otp_init(void) { int ret; stampit(); ret = misc_register(&bfin_otp_misc_device); if (ret) { pr_init(KERN_ERR PFX "unable to register a misc device\n"); return ret; } pr_init(KERN_INFO PFX "initialized\n"); return 0; } /** * bfin_otp_exit - Deinitialize module * * Unregisters the device and notifier handler. Actual device * deinitialization is handled by bfin_otp_close(). */ static void __exit bfin_otp_exit(void) { stampit(); misc_deregister(&bfin_otp_misc_device); } module_init(bfin_otp_init); module_exit(bfin_otp_exit); MODULE_AUTHOR("Mike Frysinger <vapier@gentoo.org>"); MODULE_DESCRIPTION("Blackfin OTP Memory Interface"); MODULE_LICENSE("GPL");