Support reads of arbitrary range

That means you can tell flashrom to read exactly bytes 12345-56789
(start 12345, length 44445) and it will not fetch a single byte more.

Uwe tested this on one LPC, one SPI, and one parallel flash board.

Corresponding to flashrom svn r596.
Signed-off-by: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006@gmx.net>
Acked-by: Uwe Hermann <uwe@hermann-uwe.de>

flash.h

@@ -167,7 +167,7 @@ struct flashchip {
 	int probe_timing;
 	int (*erase) (struct flashchip *flash);
 	int (*write) (struct flashchip *flash, uint8_t *buf);
-	int (*read) (struct flashchip *flash, uint8_t *buf);
+	int (*read) (struct flashchip *flash, uint8_t *buf, int start, int len);
 
 	/* Some flash devices have an additional register space. */
 	chipaddr virtual_memory;
@@ -362,7 +362,7 @@ extern struct pcidev_status satas_sii[];
 extern int verbose;
 #define printf_debug(x...) { if (verbose) printf(x); }
 void map_flash_registers(struct flashchip *flash);
-int read_memmapped(struct flashchip *flash, uint8_t *buf);
+int read_memmapped(struct flashchip *flash, uint8_t *buf, int start, int len);
 int min(int a, int b);
 int max(int a, int b);
 int check_erased_range(struct flashchip *flash, int start, int len);
@@ -408,13 +408,13 @@ int spi_block_erase_52(const struct flashchip *flash, unsigned long addr);
 int spi_block_erase_d8(const struct flashchip *flash, unsigned long addr);
 int spi_chip_write_1(struct flashchip *flash, uint8_t *buf);
 int spi_chip_write_256(struct flashchip *flash, uint8_t *buf);
-int spi_chip_read(struct flashchip *flash, uint8_t *buf);
+int spi_chip_read(struct flashchip *flash, uint8_t *buf, int start, int len);
 uint8_t spi_read_status_register(void);
 int spi_disable_blockprotect(void);
 void spi_byte_program(int address, uint8_t byte);
 int spi_nbyte_program(int address, uint8_t *bytes, int len);
 int spi_nbyte_read(int address, uint8_t *bytes, int len);
-int spi_read_chunked(struct flashchip *flash, uint8_t *buf, int chunksize);
+int spi_read_chunked(struct flashchip *flash, uint8_t *buf, int start, int len, int chunksize);
 int spi_aai_write(struct flashchip *flash, uint8_t *buf);
 uint32_t spi_get_valid_read_addr(void);
 
@@ -440,7 +440,7 @@ int write_en29f002a(struct flashchip *flash, uint8_t *buf);
 int ich_init_opcodes(void);
 int ich_spi_command(unsigned int writecnt, unsigned int readcnt,
 		    const unsigned char *writearr, unsigned char *readarr);
-int ich_spi_read(struct flashchip *flash, uint8_t * buf);
+int ich_spi_read(struct flashchip *flash, uint8_t *buf, int start, int len);
 int ich_spi_write_256(struct flashchip *flash, uint8_t * buf);
 
 /* it87spi.c */
@@ -451,14 +451,14 @@ int it87spi_init(void);
 int it87xx_probe_spi_flash(const char *name);
 int it8716f_spi_command(unsigned int writecnt, unsigned int readcnt,
 			const unsigned char *writearr, unsigned char *readarr);
-int it8716f_spi_chip_read(struct flashchip *flash, uint8_t *buf);
+int it8716f_spi_chip_read(struct flashchip *flash, uint8_t *buf, int start, int len);
 int it8716f_spi_chip_write_1(struct flashchip *flash, uint8_t *buf);
 int it8716f_spi_chip_write_256(struct flashchip *flash, uint8_t *buf);
 
 /* sb600spi.c */
 int sb600_spi_command(unsigned int writecnt, unsigned int readcnt,
 		      const unsigned char *writearr, unsigned char *readarr);
-int sb600_spi_read(struct flashchip *flash, uint8_t *buf);
+int sb600_spi_read(struct flashchip *flash, uint8_t *buf, int start, int len);
 int sb600_spi_write_1(struct flashchip *flash, uint8_t *buf);
 uint8_t sb600_read_status_register(void);
 extern uint8_t *sb600_spibar;
@@ -557,7 +557,7 @@ int write_49f002(struct flashchip *flash, uint8_t *buf);
 int wbsio_check_for_spi(const char *name);
 int wbsio_spi_command(unsigned int writecnt, unsigned int readcnt,
 		      const unsigned char *writearr, unsigned char *readarr);
-int wbsio_spi_read(struct flashchip *flash, uint8_t *buf);
+int wbsio_spi_read(struct flashchip *flash, uint8_t *buf, int start, int len);
 int wbsio_spi_write_1(struct flashchip *flash, uint8_t *buf);
 
 /* stm50flw0x0x.c */

flashrom.c

@@ -194,9 +194,9 @@ void map_flash_registers(struct flashchip *flash)
 	flash->virtual_registers = (chipaddr)programmer_map_flash_region("flash chip registers", (0xFFFFFFFF - 0x400000 - size + 1), size);
 }
 
-int read_memmapped(struct flashchip *flash, uint8_t *buf)
+int read_memmapped(struct flashchip *flash, uint8_t *buf, int start, int len)
 {
-	chip_readn(buf, flash->virtual_memory, flash->total_size * 1024);
+	chip_readn(buf, flash->virtual_memory + start, len);
 		
 	return 0;
 }
@@ -393,7 +393,7 @@ int verify_flash(struct flashchip *flash, uint8_t *buf)
 		fprintf(stderr, "ERROR: flashrom has no read function for this flash chip.\n");
 		return 1;
 	} else
-		flash->read(flash, buf2);
+		flash->read(flash, buf2, 0, total_size);
 
 	printf("Verifying flash... ");
 
@@ -446,7 +446,7 @@ int read_flash(struct flashchip *flash, char *filename, unsigned int exclude_sta
 		fprintf(stderr, "ERROR: flashrom has no read function for this flash chip.\n");
 		return 1;
 	} else
-		flash->read(flash, buf);
+		flash->read(flash, buf, 0, size);
 
 	if (exclude_end_position - exclude_start_position > 0)
 		memset(buf + exclude_start_position, 0,
@@ -482,7 +482,7 @@ int erase_flash(struct flashchip *flash)
 		fprintf(stderr, "ERROR: flashrom has no read function for this flash chip.\n");
 		return 1;
 	} else
-		flash->read(flash, buf);
+		flash->read(flash, buf, 0, size);
 
 	for (erasedbytes = 0; erasedbytes < size; erasedbytes++)
 		if (0xff != buf[erasedbytes]) {
@@ -915,6 +915,7 @@ int main(int argc, char *argv[])
 	 * completely once all flash chips can do rom layouts. stepan
 	 */
 
+	/* FIXME: This code is totally broken. It treats exclude ranges as include ranges. */
 	// ////////////////////////////////////////////////////////////
 	if (exclude_end_position - exclude_start_position > 0)
 		chip_readn(buf + exclude_start_position,

ichspi.c

@@ -647,14 +647,14 @@ static int ich_spi_write_page(struct flashchip *flash, uint8_t * bytes,
 	return 0;
 }
 
-int ich_spi_read(struct flashchip *flash, uint8_t * buf)
+int ich_spi_read(struct flashchip *flash, uint8_t * buf, int start, int len)
 {
 	int maxdata = 64;
 
 	if (spi_controller == SPI_CONTROLLER_VIA)
 		maxdata = 16;
 
-	return spi_read_chunked(flash, buf, maxdata);
+	return spi_read_chunked(flash, buf, start, len, maxdata);
 }
 
 int ich_spi_write_256(struct flashchip *flash, uint8_t * buf)

it87spi.c

@@ -257,15 +257,15 @@ int it8716f_spi_chip_write_1(struct flashchip *flash, uint8_t *buf)
  * IT8716F only allows maximum of 512 kb SPI mapped to LPC memory cycles
  * Need to read this big flash using firmware cycles 3 byte at a time.
  */
-int it8716f_spi_chip_read(struct flashchip *flash, uint8_t *buf)
+int it8716f_spi_chip_read(struct flashchip *flash, uint8_t *buf, int start, int len)
 {
 	int total_size = 1024 * flash->total_size;
 	fast_spi = 0;
 
 	if ((programmer == PROGRAMMER_IT87SPI) || (total_size > 512 * 1024)) {
-		spi_read_chunked(flash, buf, 3);
+		spi_read_chunked(flash, buf, start, len, 3);
 	} else {
-		read_memmapped(flash, buf);
+		read_memmapped(flash, buf, start, len);
 	}
 
 	return 0;

sb600spi.c

@@ -39,10 +39,10 @@ struct sb600_spi_controller {
 struct sb600_spi_controller *spi_bar = NULL;
 uint8_t *sb600_spibar;
 
-int sb600_spi_read(struct flashchip *flash, uint8_t *buf)
+int sb600_spi_read(struct flashchip *flash, uint8_t *buf, int start, int len)
 {
 	/* Maximum read length is 8 bytes. */
-	return spi_read_chunked(flash, buf, 8);
+	return spi_read_chunked(flash, buf, start, len, 8);
 }
 
 uint8_t sb600_read_status_register(void)

spi.c

@@ -678,19 +678,31 @@ int spi_nbyte_read(int address, uint8_t *bytes, int len)
  * Read a complete flash chip.
  * Each page is read separately in chunks with a maximum size of chunksize.
  */
-int spi_read_chunked(struct flashchip *flash, uint8_t *buf, int chunksize)
+int spi_read_chunked(struct flashchip *flash, uint8_t *buf, int start, int len, int chunksize)
 {
 	int rc = 0;
-	int i, j;
-	int total_size = flash->total_size * 1024;
+	int i, j, starthere, lenhere;
 	int page_size = flash->page_size;
 	int toread;
 
-	for (j = 0; j < total_size / page_size; j++) {
-		for (i = 0; i < page_size; i += chunksize) {
-			toread = min(chunksize, page_size - i);
-			rc = spi_nbyte_read(j * page_size + i,
-					    buf + j * page_size + i, toread);
+	/* Warning: This loop has a very unusual condition and body.
+	 * The loop needs to go through each page with at least one affected
+	 * byte. The lowest page number is (start / page_size) since that
+	 * division rounds down. The highest page number we want is the page
+	 * where the last byte of the range lives. That last byte has the
+	 * address (start + len - 1), thus the highest page number is
+	 * (start + len - 1) / page_size. Since we want to include that last
+	 * page as well, the loop condition uses <=.
+	 */
+	for (i = start / page_size; i <= (start + len - 1) / page_size; i++) {
+		/* Byte position of the first byte in the range in this page. */
+		/* starthere is an offset to the base address of the chip. */
+		starthere = max(start, i * page_size);
+		/* Length of bytes in the range in this page. */
+		lenhere = min(start + len, (i + 1) * page_size) - starthere;
+		for (j = 0; j < lenhere; j += chunksize) {
+			toread = min(chunksize, lenhere - j);
+			rc = spi_nbyte_read(starthere + j, buf + starthere - start + j, toread);
 			if (rc)
 				break;
 		}
@@ -701,19 +713,19 @@ int spi_read_chunked(struct flashchip *flash, uint8_t *buf, int chunksize)
 	return rc;
 }
 
-int spi_chip_read(struct flashchip *flash, uint8_t *buf)
+int spi_chip_read(struct flashchip *flash, uint8_t *buf, int start, int len)
 {
 	switch (spi_controller) {
 	case SPI_CONTROLLER_IT87XX:
-		return it8716f_spi_chip_read(flash, buf);
+		return it8716f_spi_chip_read(flash, buf, start, len);
 	case SPI_CONTROLLER_SB600:
-		return sb600_spi_read(flash, buf);
+		return sb600_spi_read(flash, buf, start, len);
 	case SPI_CONTROLLER_ICH7:
 	case SPI_CONTROLLER_ICH9:
 	case SPI_CONTROLLER_VIA:
-		return ich_spi_read(flash, buf);
+		return ich_spi_read(flash, buf, start, len);
 	case SPI_CONTROLLER_WBSIO:
-		return wbsio_spi_read(flash, buf);
+		return wbsio_spi_read(flash, buf, start, len);
 	default:
 		printf_debug
 		    ("%s called, but no SPI chipset/strapping detected\n",

wbsio_spi.c

@@ -173,7 +173,7 @@ int wbsio_spi_command(unsigned int writecnt, unsigned int readcnt,
 	return 0;
 }
 
-int wbsio_spi_read(struct flashchip *flash, uint8_t *buf)
+int wbsio_spi_read(struct flashchip *flash, uint8_t *buf, int start, int len)
 {
 	int size = flash->total_size * 1024;
 
@@ -182,7 +182,7 @@ int wbsio_spi_read(struct flashchip *flash, uint8_t *buf)
 		return 1;
 	}
 
-	read_memmapped(flash, buf);
+	read_memmapped(flash, buf, start, len);
 	return 0;
 }