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21 * library without restriction. Specifically, if other files instantiate
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29 * Copyright 2009 Develer S.r.l. (http://www.develer.com/)
33 * \defgroup io_kblock KBlock interface
37 * \brief KBlock interface
39 * A block device is a device which can only be read/written
40 * with data blocks of constant size: flash memories,
41 * SD cards, hard disks, etc...
42 * This interface is designed to adapt to most block devices and
43 * use peculiar features in order to save CPU time and memory space.
45 * There is no init function because you do not have to use this
46 * structure directly, specific implementations will supply their own init
49 * Error handling is done in a way similar to standard C library: whenever a
50 * function (eg. kblock_flush()) returns error, you need to check the error
51 * code, which is implementation specific.
53 * Example of code flow:
55 * // init a KBlock-derived class
57 * flash_init(&fls.blk, 0);
59 * // use kblock_* functions to access the derived class
60 * kblock_write(&fls.blk, ...);
61 * if (kblock_flush(&fls.blk) == EOF)
63 * // oops, error occurred!
64 * int err = kblock_error(&fls.blk);
65 * // handle Flash specific error conditions
67 * // clear error condition
68 * kblock_clearerr(&fls.blk);
72 * \author Francesco Sacchi <batt@develer.com>
74 * $WIZ$ module_name = "kblock"
80 #include <cfg/compiler.h>
81 #include <cfg/debug.h>
82 #include <cfg/macros.h>
84 /** Type for addressing blocks in the device. */
85 typedef uint32_t block_idx_t;
91 * \name Prototypes for KBlock low level access functions.
93 * When writing a driver implementing the KBlock interface you can choose which
94 * function subset to implement, but you have to set to NULL unimplemented
99 typedef size_t (* kblock_read_direct_t) (struct KBlock *b, block_idx_t index, void *buf, size_t offset, size_t size);
100 typedef size_t (* kblock_write_direct_t) (struct KBlock *b, block_idx_t index, const void *buf, size_t offset, size_t size);
102 typedef size_t (* kblock_read_t) (struct KBlock *b, void *buf, size_t offset, size_t size);
103 typedef size_t (* kblock_write_t) (struct KBlock *b, const void *buf, size_t offset, size_t size);
104 typedef int (* kblock_load_t) (struct KBlock *b, block_idx_t index);
105 typedef int (* kblock_store_t) (struct KBlock *b, block_idx_t index);
107 typedef int (* kblock_error_t) (struct KBlock *b);
108 typedef void (* kblock_clearerr_t) (struct KBlock *b);
109 typedef int (* kblock_close_t) (struct KBlock *b);
113 * Table of interface functions for a KBlock device.
115 typedef struct KBlockVTable
117 kblock_read_direct_t readDirect;
118 kblock_write_direct_t writeDirect;
120 kblock_read_t readBuf;
121 kblock_write_t writeBuf;
123 kblock_store_t store;
125 kblock_error_t error; // \sa kblock_error()
126 kblock_clearerr_t clearerr; // \sa kblock_clearerr()
128 kblock_close_t close; // \sa kblock_close()
132 #define KB_BUFFERED BV(0) ///< Internal flag: true if the KBlock has a buffer
133 #define KB_CACHE_DIRTY BV(1) ///< Internal flag: true if the cache is dirty
134 #define KB_PARTIAL_WRITE BV(2) ///< Internal flag: true if the device allows partial block write
138 * KBlock private members.
139 * These are the private members of the KBlock interface, please do not
140 * access these directly, use the KBlock API.
142 typedef struct KBlockPriv
144 DB(id_t type); // Used to keep track, at runtime, of the class type.
145 int flags; // Status and error flags.
146 void *buf; // Pointer to the page buffer for RAM-cached KBlocks.
147 block_idx_t blk_start; // Start block number when the device is trimmed. \sa kblock_trim().
148 block_idx_t curr_blk; // Current cached block number in cached KBlocks.
150 const struct KBlockVTable *vt; // Virtual table of interface functions.
154 * KBlock: interface for a generic block device.
157 typedef struct KBlock
159 KBlockPriv priv; ///< Interface private data, do not use directly.
161 /* Public access members */
162 size_t blk_size; ///< Block size.
163 block_idx_t blk_cnt; ///< Number of blocks available in the device.
168 * Use a subset of the blocks on the device.
170 * This function is useful for partitioning a device and use it for
171 * different purposes at the same time.
173 * This function will limit the number of blocks used on the device by setting
174 * a start index and a number of blocks to be used counting from that index.
176 * The blocks outside this range are no more accessible.
178 * Logical block indexes will be mapped to physical indexes inside this new
179 * range automatically. Even following calls to kblock_trim() will use logical
180 * indexes, so, once trimmed, access can only be limited further and never
185 * //...init KBlock device dev
186 * kblock_trim(dev, 200, 1500); // Restrict access to the 200-1700 physical block range.
187 * kblock_read(dev, 0, buf, 0, dev->blk_size); // Read from physical block #200.
188 * kblock_trim(dev, 0, 300); // Restrict access to the 200-500 physical block range.
191 * \param b KBlock device.
192 * \param start The index of the start block for the limiting window in logical addressing units.
193 * \param count The number of blocks to be used.
196 INLINE void kblock_trim(struct KBlock *b, block_idx_t start, block_idx_t count)
198 ASSERT(start + count <= b->blk_cnt);
199 b->priv.blk_start += start;
204 #define KB_ASSERT_METHOD(b, method) \
208 ASSERT((b)->priv.vt); \
209 ASSERT((b)->priv.vt->method); \
215 * Get the current errors for the device.
217 * \note Calling this function will not clear the errors.
219 * \param b KBlock device.
221 * \return 0 if no error is present, a driver specific mask of errors otherwise.
223 * \sa kblock_clearerr()
225 INLINE int kblock_error(struct KBlock *b)
227 KB_ASSERT_METHOD(b, error);
228 return b->priv.vt->error(b);
232 * Clear the errors of the device.
234 * \param b KBlock device.
239 INLINE void kblock_clearerr(struct KBlock *b)
241 KB_ASSERT_METHOD(b, clearerr);
242 b->priv.vt->clearerr(b);
247 * Flush the cache (if any) to the device.
249 * This function will write any pending modifications to the device.
250 * If the device does not have a cache, this function will do nothing.
252 * \return 0 if all is OK, EOF on errors.
253 * \sa kblock_read(), kblock_write(), kblock_buffered().
255 int kblock_flush(struct KBlock *b);
260 * \param b KBlock device.
262 * \return 0 on success, EOF on errors.
264 INLINE int kblock_close(struct KBlock *b)
266 KB_ASSERT_METHOD(b, close);
267 return kblock_flush(b) | b->priv.vt->close(b);
271 * \return true if the device \a b is buffered, false otherwise.
272 * \param b KBlock device.
273 * \sa kblock_cachedBlock(), kblock_cacheDirty().
275 INLINE bool kblock_buffered(struct KBlock *b)
278 return (b->priv.flags & KB_BUFFERED);
283 * \return The current cached block number if the device is buffered.
284 * \param b KBlock device.
285 * \note This function will throw an ASSERT if called on a non buffered KBlock.
286 * \sa kblock_buffered(), kblock_cacheDirty().
288 INLINE block_idx_t kblock_cachedBlock(struct KBlock *b)
290 ASSERT(kblock_buffered(b));
291 return b->priv.curr_blk;
296 * Return the status of the internal cache.
298 * \param b KBlock device.
299 * \return If the device supports buffering, returns true if the cache is dirty,
300 * false if the cache is clean and coherent with device content.
301 * \note This function will throw an ASSERT if called on a non buffered KBlock.
302 * \sa kblock_cachedBlock(), kblock_buffered().
304 INLINE bool kblock_cacheDirty(struct KBlock *b)
306 ASSERT(kblock_buffered(b));
307 return kblock_buffered(b) && (b->priv.flags & KB_CACHE_DIRTY);
311 * \return true if the device \a b supports partial block write. That is, you
312 * can call kblock_write() with a size which is lesser than the block
314 * \param b KBlock device.
315 * \sa kblock_write().
317 INLINE bool kblock_partialWrite(struct KBlock *b)
320 return (b->priv.flags & KB_PARTIAL_WRITE);
324 * Read data from the block device.
326 * This function will read \a size bytes from block \a idx starting at
327 * address \a offset inside the block.
329 * Most block devices (almost all flash memories, for instance),
330 * can efficiently read even a part of the block.
332 * \note This function can be slow if you try to partial read a block from
333 * a device which does not support partial block reads and is opened
334 * in unbuffered mode.
336 * \param b KBlock device.
337 * \param idx the block number where you want to read.
338 * \param buf a buffer where the data will be read.
339 * \param offset the offset inside the block from which data reading will start.
340 * \param size the size of data to be read.
342 * \return the number of bytes read.
344 * \sa kblock_write().
346 size_t kblock_read(struct KBlock *b, block_idx_t idx, void *buf, size_t offset, size_t size);
350 * Write data to the block device.
352 * This function will write \a size bytes to block \a idx starting at
353 * address \a offset inside the block.
355 * \note Partial block writes are supported only on certain devices.
356 * You can use kblock_partialWrite() in order to check if the device
357 * has this feature or not.
359 * \note If the device is opened in buffered mode, this function will use
360 * efficiently and trasparently the cache provided.
361 * In order to be sure that all modifications are actually written
362 * to the device you have to call kblock_flush().
364 * \param b KBlock device.
365 * \param idx the block number where you want to write.
366 * \param buf a pointer to the data to be written.
367 * \param offset the offset inside the block from which data writing will start.
368 * \param size the size of data to be written.
370 * \return the number of bytes written.
372 * \sa kblock_read(), kblock_flush(), kblock_buffered(), kblock_partialWrite().
374 size_t kblock_write(struct KBlock *b, block_idx_t idx, const void *buf, size_t offset, size_t size);
377 * Copy one block to another.
379 * This function will copy the content of block \a src to block \a dest.
381 * \note This function is available only on devices which support partial
382 * block write or are opened in buffered mode.
384 * \param b KBlock device.
385 * \param src source block number.
386 * \param dest destination block number.
388 * \return 0 if all is OK, EOF on errors.
390 int kblock_copy(struct KBlock *b, block_idx_t src, block_idx_t dest);
392 int kblock_swLoad(struct KBlock *b, block_idx_t index);
393 int kblock_swStore(struct KBlock *b, block_idx_t index);
394 size_t kblock_swReadBuf(struct KBlock *b, void *buf, size_t offset, size_t size);
395 size_t kblock_swWriteBuf(struct KBlock *b, const void *buf, size_t offset, size_t size);
396 int kblock_swClose(struct KBlock *b);
398 /** \} */ //defgroup io_kblock
401 #endif /* IO_KBLOCK_H */