- 根目录:
- drivers
- char
- tile-srom.c
/*
* 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;
}
}
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, &srom_parent->dev,
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 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;
/* 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:
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;
}
/** 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);
}
module_init(srom_init);
module_exit(srom_cleanup);