tile-srom.c 11.6 KB
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472
/*
 * 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);