diff options
Diffstat (limited to 'drivers/char/tile-srom.c')
| -rw-r--r-- | drivers/char/tile-srom.c | 462 |
1 files changed, 462 insertions, 0 deletions
diff --git a/drivers/char/tile-srom.c b/drivers/char/tile-srom.c new file mode 100644 index 00000000000..bd377472dcf --- /dev/null +++ b/drivers/char/tile-srom.c @@ -0,0 +1,462 @@ +/* + * Copyright 2011 Tilera Corporation. All Rights Reserved. + * + * 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, version 2. + * + * 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, GOOD TITLE or + * NON INFRINGEMENT. See the GNU General Public License for + * more details. + * + * SPI Flash ROM driver + * + * This source code is derived from code provided in "Linux Device + * Drivers, Third Edition", by Jonathan Corbet, Alessandro Rubini, and + * Greg Kroah-Hartman, published by O'Reilly Media, Inc. + */ + +#include <linux/module.h> +#include <linux/moduleparam.h> +#include <linux/kernel.h> /* printk() */ +#include <linux/slab.h> /* kmalloc() */ +#include <linux/fs.h> /* everything... */ +#include <linux/errno.h> /* error codes */ +#include <linux/types.h> /* size_t */ +#include <linux/proc_fs.h> +#include <linux/fcntl.h> /* O_ACCMODE */ +#include <linux/aio.h> +#include <linux/pagemap.h> +#include <linux/hugetlb.h> +#include <linux/uaccess.h> +#include <linux/platform_device.h> +#include <hv/hypervisor.h> +#include <linux/ioctl.h> +#include <linux/cdev.h> +#include <linux/delay.h> +#include <hv/drv_srom_intf.h> + +/* + * Size of our hypervisor I/O requests. We break up large transfers + * so that we don't spend large uninterrupted spans of time in the + * hypervisor. Erasing an SROM sector takes a significant fraction of + * a second, so if we allowed the user to, say, do one I/O to write the + * entire ROM, we'd get soft lockup timeouts, or worse. + */ +#define SROM_CHUNK_SIZE ((size_t)4096) + +/* + * When hypervisor is busy (e.g. erasing), poll the status periodically. + */ + +/* + * Interval to poll the state in msec + */ +#define SROM_WAIT_TRY_INTERVAL 20 + +/* + * Maximum times to poll the state + */ +#define SROM_MAX_WAIT_TRY_TIMES 1000 + +struct srom_dev { + int hv_devhdl; /* Handle for hypervisor device */ + u32 total_size; /* Size of this device */ + u32 sector_size; /* Size of a sector */ + u32 page_size; /* Size of a page */ + struct mutex lock; /* Allow only one accessor at a time */ +}; + +static int srom_major; /* Dynamic major by default */ +module_param(srom_major, int, 0); +MODULE_AUTHOR("Tilera Corporation"); +MODULE_LICENSE("GPL"); + +static int srom_devs; /* Number of SROM partitions */ +static struct cdev srom_cdev; +static struct class *srom_class; +static struct srom_dev *srom_devices; + +/* + * Handle calling the hypervisor and managing EAGAIN/EBUSY. + */ + +static ssize_t _srom_read(int hv_devhdl, void *buf, + loff_t off, size_t count) +{ + int retval, retries = SROM_MAX_WAIT_TRY_TIMES; + for (;;) { + retval = hv_dev_pread(hv_devhdl, 0, (HV_VirtAddr)buf, + count, off); + if (retval >= 0) + return retval; + if (retval == HV_EAGAIN) + continue; + if (retval == HV_EBUSY && --retries > 0) { + msleep(SROM_WAIT_TRY_INTERVAL); + continue; + } + pr_err("_srom_read: error %d\n", retval); + return -EIO; + } +} + +static ssize_t _srom_write(int hv_devhdl, const void *buf, + loff_t off, size_t count) +{ + int retval, retries = SROM_MAX_WAIT_TRY_TIMES; + for (;;) { + retval = hv_dev_pwrite(hv_devhdl, 0, (HV_VirtAddr)buf, + count, off); + if (retval >= 0) + return retval; + if (retval == HV_EAGAIN) + continue; + if (retval == HV_EBUSY && --retries > 0) { + msleep(SROM_WAIT_TRY_INTERVAL); + continue; + } + pr_err("_srom_write: error %d\n", retval); + return -EIO; + } +} + +/** + * srom_open() - Device open routine. + * @inode: Inode for this device. + * @filp: File for this specific open of the device. + * + * Returns zero, or an error code. + */ +static int srom_open(struct inode *inode, struct file *filp) +{ + filp->private_data = &srom_devices[iminor(inode)]; + return 0; +} + + +/** + * srom_release() - Device release routine. + * @inode: Inode for this device. + * @filp: File for this specific open of the device. + * + * Returns zero, or an error code. + */ +static int srom_release(struct inode *inode, struct file *filp) +{ + struct srom_dev *srom = filp->private_data; + char dummy; + + /* Make sure we've flushed anything written to the ROM. */ + mutex_lock(&srom->lock); + if (srom->hv_devhdl >= 0) + _srom_write(srom->hv_devhdl, &dummy, SROM_FLUSH_OFF, 1); + mutex_unlock(&srom->lock); + + filp->private_data = NULL; + + return 0; +} + + +/** + * srom_read() - Read data from the device. + * @filp: File for this specific open of the device. + * @buf: User's data buffer. + * @count: Number of bytes requested. + * @f_pos: File position. + * + * Returns number of bytes read, or an error code. + */ +static ssize_t srom_read(struct file *filp, char __user *buf, + size_t count, loff_t *f_pos) +{ + int retval = 0; + void *kernbuf; + struct srom_dev *srom = filp->private_data; + + kernbuf = kmalloc(SROM_CHUNK_SIZE, GFP_KERNEL); + if (!kernbuf) + return -ENOMEM; + + if (mutex_lock_interruptible(&srom->lock)) { + retval = -ERESTARTSYS; + kfree(kernbuf); + return retval; + } + + while (count) { + int hv_retval; + int bytes_this_pass = min(count, SROM_CHUNK_SIZE); + + hv_retval = _srom_read(srom->hv_devhdl, kernbuf, + *f_pos, bytes_this_pass); + if (hv_retval <= 0) { + if (retval == 0) + retval = hv_retval; + break; + } + + if (copy_to_user(buf, kernbuf, hv_retval) != 0) { + retval = -EFAULT; + break; + } + + retval += hv_retval; + *f_pos += hv_retval; + buf += hv_retval; + count -= hv_retval; + } + + mutex_unlock(&srom->lock); + kfree(kernbuf); + + return retval; +} + +/** + * srom_write() - Write data to the device. + * @filp: File for this specific open of the device. + * @buf: User's data buffer. + * @count: Number of bytes requested. + * @f_pos: File position. + * + * Returns number of bytes written, or an error code. + */ +static ssize_t srom_write(struct file *filp, const char __user *buf, + size_t count, loff_t *f_pos) +{ + int retval = 0; + void *kernbuf; + struct srom_dev *srom = filp->private_data; + + kernbuf = kmalloc(SROM_CHUNK_SIZE, GFP_KERNEL); + if (!kernbuf) + return -ENOMEM; + + if (mutex_lock_interruptible(&srom->lock)) { + retval = -ERESTARTSYS; + kfree(kernbuf); + return retval; + } + + while (count) { + int hv_retval; + int bytes_this_pass = min(count, SROM_CHUNK_SIZE); + + if (copy_from_user(kernbuf, buf, bytes_this_pass) != 0) { + retval = -EFAULT; + break; + } + + hv_retval = _srom_write(srom->hv_devhdl, kernbuf, + *f_pos, bytes_this_pass); + if (hv_retval <= 0) { + if (retval == 0) + retval = hv_retval; + break; + } + + retval += hv_retval; + *f_pos += hv_retval; + buf += hv_retval; + count -= hv_retval; + } + + mutex_unlock(&srom->lock); + kfree(kernbuf); + + return retval; +} + +/* Provide our own implementation so we can use srom->total_size. */ +loff_t srom_llseek(struct file *file, loff_t offset, int origin) +{ + struct srom_dev *srom = file->private_data; + return fixed_size_llseek(file, offset, origin, srom->total_size); +} + +static ssize_t total_size_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct srom_dev *srom = dev_get_drvdata(dev); + return sprintf(buf, "%u\n", srom->total_size); +} +static DEVICE_ATTR_RO(total_size); + +static ssize_t sector_size_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct srom_dev *srom = dev_get_drvdata(dev); + return sprintf(buf, "%u\n", srom->sector_size); +} +static DEVICE_ATTR_RO(sector_size); + +static ssize_t page_size_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct srom_dev *srom = dev_get_drvdata(dev); + return sprintf(buf, "%u\n", srom->page_size); +} +static DEVICE_ATTR_RO(page_size); + +static struct attribute *srom_dev_attrs[] = { + &dev_attr_total_size.attr, + &dev_attr_sector_size.attr, + &dev_attr_page_size.attr, + NULL, +}; +ATTRIBUTE_GROUPS(srom_dev); + +static char *srom_devnode(struct device *dev, umode_t *mode) +{ + *mode = S_IRUGO | S_IWUSR; + return kasprintf(GFP_KERNEL, "srom/%s", dev_name(dev)); +} + +/* + * The fops + */ +static const struct file_operations srom_fops = { + .owner = THIS_MODULE, + .llseek = srom_llseek, + .read = srom_read, + .write = srom_write, + .open = srom_open, + .release = srom_release, +}; + +/** + * srom_setup_minor() - Initialize per-minor information. + * @srom: Per-device SROM state. + * @index: Device to set up. + */ +static int srom_setup_minor(struct srom_dev *srom, int index) +{ + struct device *dev; + int devhdl = srom->hv_devhdl; + + mutex_init(&srom->lock); + + if (_srom_read(devhdl, &srom->total_size, + SROM_TOTAL_SIZE_OFF, sizeof(srom->total_size)) < 0) + return -EIO; + if (_srom_read(devhdl, &srom->sector_size, + SROM_SECTOR_SIZE_OFF, sizeof(srom->sector_size)) < 0) + return -EIO; + if (_srom_read(devhdl, &srom->page_size, + SROM_PAGE_SIZE_OFF, sizeof(srom->page_size)) < 0) + return -EIO; + + dev = device_create(srom_class, &platform_bus, + MKDEV(srom_major, index), srom, "%d", index); + return PTR_ERR_OR_ZERO(dev); +} + +/** srom_init() - Initialize the driver's module. */ +static int srom_init(void) +{ + int result, i; + dev_t dev = MKDEV(srom_major, 0); + + /* + * Start with a plausible number of partitions; the krealloc() call + * below will yield about log(srom_devs) additional allocations. + */ + srom_devices = kzalloc(4 * sizeof(struct srom_dev), GFP_KERNEL); + + /* Discover the number of srom partitions. */ + for (i = 0; ; i++) { + int devhdl; + char buf[20]; + struct srom_dev *new_srom_devices = + krealloc(srom_devices, (i+1) * sizeof(struct srom_dev), + GFP_KERNEL | __GFP_ZERO); + if (!new_srom_devices) { + result = -ENOMEM; + goto fail_mem; + } + srom_devices = new_srom_devices; + sprintf(buf, "srom/0/%d", i); + devhdl = hv_dev_open((HV_VirtAddr)buf, 0); + if (devhdl < 0) { + if (devhdl != HV_ENODEV) + pr_notice("srom/%d: hv_dev_open failed: %d.\n", + i, devhdl); + break; + } + srom_devices[i].hv_devhdl = devhdl; + } + srom_devs = i; + + /* Bail out early if we have no partitions at all. */ + if (srom_devs == 0) { + result = -ENODEV; + goto fail_mem; + } + + /* Register our major, and accept a dynamic number. */ + if (srom_major) + result = register_chrdev_region(dev, srom_devs, "srom"); + else { + result = alloc_chrdev_region(&dev, 0, srom_devs, "srom"); + srom_major = MAJOR(dev); + } + if (result < 0) + goto fail_mem; + + /* Register a character device. */ + cdev_init(&srom_cdev, &srom_fops); + srom_cdev.owner = THIS_MODULE; + srom_cdev.ops = &srom_fops; + result = cdev_add(&srom_cdev, dev, srom_devs); + if (result < 0) + goto fail_chrdev; + + /* Create a sysfs class. */ + srom_class = class_create(THIS_MODULE, "srom"); + if (IS_ERR(srom_class)) { + result = PTR_ERR(srom_class); + goto fail_cdev; + } + srom_class->dev_groups = srom_dev_groups; + srom_class->devnode = srom_devnode; + + /* Do per-partition initialization */ + for (i = 0; i < srom_devs; i++) { + result = srom_setup_minor(srom_devices + i, i); + if (result < 0) + goto fail_class; + } + + return 0; + +fail_class: + for (i = 0; i < srom_devs; i++) + device_destroy(srom_class, MKDEV(srom_major, i)); + class_destroy(srom_class); +fail_cdev: + cdev_del(&srom_cdev); +fail_chrdev: + unregister_chrdev_region(dev, srom_devs); +fail_mem: + kfree(srom_devices); + return result; +} + +/** srom_cleanup() - Clean up the driver's module. */ +static void srom_cleanup(void) +{ + int i; + for (i = 0; i < srom_devs; i++) + device_destroy(srom_class, MKDEV(srom_major, i)); + class_destroy(srom_class); + cdev_del(&srom_cdev); + unregister_chrdev_region(MKDEV(srom_major, 0), srom_devs); + kfree(srom_devices); +} + +module_init(srom_init); +module_exit(srom_cleanup); |