cregit-Linux how code gets into the kernel

Release 4.10 drivers/char/tile-srom.c

Directory: drivers/char
/*
 * 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/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 platform_device *srom_parent;

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; } }

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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; } }

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/** * 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; }

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/** * 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; }

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/** * 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; }

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/** * 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; }

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/* 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); }

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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); }

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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); }

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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); }

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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) { if (mode) *mode = 0644; return kasprintf(GFP_KERNEL, "srom/%s", dev_name(dev)); }

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/* * 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. * @devhdl: Partition device handle. */
static int srom_setup_minor(struct srom_dev *srom, int devhdl) { srom->hv_devhdl = 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; return 0; }

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/** 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 = kmalloc(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); 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; } result = srom_setup_minor(&srom_devices[i], devhdl); if (result != 0) goto fail_mem; } 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 parent device */ srom_parent = platform_device_register_simple("srom", -1, NULL, 0); if (IS_ERR(srom_parent)) { result = PTR_ERR(srom_parent); goto fail_pdev; } /* 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; /* Create per-partition devices */ for (i = 0; i < srom_devs; i++) { struct device *dev = device_create(srom_class, &srom_parent->dev, MKDEV(srom_major, i), srom_devices + i, "%d", i); result = PTR_ERR_OR_ZERO(dev); 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: platform_device_unregister(srom_parent); fail_pdev: cdev_del(&srom_cdev); fail_chrdev: unregister_chrdev_region(dev, srom_devs); fail_mem: kfree(srom_devices); return result; }

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Total491100.00%4100.00%

/** 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); platform_device_unregister(srom_parent); unregister_chrdev_region(MKDEV(srom_major, 0), srom_devs); kfree(srom_devices); }

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module_init(srom_init); module_exit(srom_cleanup);

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Directory: drivers/char
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