diff options
Diffstat (limited to 'drivers/mtd/spi-nor/core.c')
| -rw-r--r-- | drivers/mtd/spi-nor/core.c | 153 |
1 files changed, 151 insertions, 2 deletions
diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c index 6267753bf2b0..5adf607b2a90 100644 --- a/drivers/mtd/spi-nor/core.c +++ b/drivers/mtd/spi-nor/core.c @@ -1697,6 +1697,82 @@ static const struct flash_info *spi_nor_detect(struct spi_nor *nor) return info; } +/* + * On Octal DTR capable flashes like Micron Xcella reads cannot start or + * end at an odd address in Octal DTR mode. Extra bytes need to be read + * at the start or end to make sure both the start address and length + * remain even. + */ +static int spi_nor_octal_dtr_read(struct spi_nor *nor, loff_t from, size_t len, + u_char *buf) +{ + u_char *tmp_buf; + size_t tmp_len; + loff_t start, end; + int ret, bytes_read; + + if (IS_ALIGNED(from, 2) && IS_ALIGNED(len, 2)) + return spi_nor_read_data(nor, from, len, buf); + else if (IS_ALIGNED(from, 2) && len > PAGE_SIZE) + return spi_nor_read_data(nor, from, round_down(len, PAGE_SIZE), + buf); + + tmp_buf = kmalloc(PAGE_SIZE, GFP_KERNEL); + if (!tmp_buf) + return -ENOMEM; + + start = round_down(from, 2); + end = round_up(from + len, 2); + + /* + * Avoid allocating too much memory. The requested read length might be + * quite large. Allocating a buffer just as large (slightly bigger, in + * fact) would put unnecessary memory pressure on the system. + * + * For example if the read is from 3 to 1M, then this will read from 2 + * to 4098. The reads from 4098 to 1M will then not need a temporary + * buffer so they can proceed as normal. + */ + tmp_len = min_t(size_t, end - start, PAGE_SIZE); + + ret = spi_nor_read_data(nor, start, tmp_len, tmp_buf); + if (ret == 0) { + ret = -EIO; + goto out; + } + if (ret < 0) + goto out; + + /* + * More bytes are read than actually requested, but that number can't be + * reported to the calling function or it will confuse its calculations. + * Calculate how many of the _requested_ bytes were read. + */ + bytes_read = ret; + + if (from != start) + ret -= from - start; + + /* + * Only account for extra bytes at the end if they were actually read. + * For example, if the total length was truncated because of temporary + * buffer size limit then the adjustment for the extra bytes at the end + * is not needed. + */ + if (start + bytes_read == end) + ret -= end - (from + len); + + if (ret < 0) { + ret = -EIO; + goto out; + } + + memcpy(buf, tmp_buf + (from - start), ret); +out: + kfree(tmp_buf); + return ret; +} + static int spi_nor_read(struct mtd_info *mtd, loff_t from, size_t len, size_t *retlen, u_char *buf) { @@ -1714,7 +1790,10 @@ static int spi_nor_read(struct mtd_info *mtd, loff_t from, size_t len, addr = spi_nor_convert_addr(nor, addr); - ret = spi_nor_read_data(nor, addr, len, buf); + if (nor->read_proto == SNOR_PROTO_8_8_8_DTR) + ret = spi_nor_octal_dtr_read(nor, addr, len, buf); + else + ret = spi_nor_read_data(nor, addr, len, buf); if (ret == 0) { /* We shouldn't see 0-length reads */ ret = -EIO; @@ -1737,6 +1816,71 @@ read_err: } /* + * On Octal DTR capable flashes like Micron Xcella the writes cannot start or + * end at an odd address in Octal DTR mode. Extra 0xff bytes need to be appended + * or prepended to make sure the start address and end address are even. 0xff is + * used because on NOR flashes a program operation can only flip bits from 1 to + * 0, not the other way round. 0 to 1 flip needs to happen via erases. + */ +static int spi_nor_octal_dtr_write(struct spi_nor *nor, loff_t to, size_t len, + const u8 *buf) +{ + u8 *tmp_buf; + size_t bytes_written; + loff_t start, end; + int ret; + + if (IS_ALIGNED(to, 2) && IS_ALIGNED(len, 2)) + return spi_nor_write_data(nor, to, len, buf); + + tmp_buf = kmalloc(nor->params->page_size, GFP_KERNEL); + if (!tmp_buf) + return -ENOMEM; + + memset(tmp_buf, 0xff, nor->params->page_size); + + start = round_down(to, 2); + end = round_up(to + len, 2); + + memcpy(tmp_buf + (to - start), buf, len); + + ret = spi_nor_write_data(nor, start, end - start, tmp_buf); + if (ret == 0) { + ret = -EIO; + goto out; + } + if (ret < 0) + goto out; + + /* + * More bytes are written than actually requested, but that number can't + * be reported to the calling function or it will confuse its + * calculations. Calculate how many of the _requested_ bytes were + * written. + */ + bytes_written = ret; + + if (to != start) + ret -= to - start; + + /* + * Only account for extra bytes at the end if they were actually + * written. For example, if for some reason the controller could only + * complete a partial write then the adjustment for the extra bytes at + * the end is not needed. + */ + if (start + bytes_written == end) + ret -= end - (to + len); + + if (ret < 0) + ret = -EIO; + +out: + kfree(tmp_buf); + return ret; +} + +/* * Write an address range to the nor chip. Data must be written in * FLASH_PAGESIZE chunks. The address range may be any size provided * it is within the physical boundaries. @@ -1780,7 +1924,12 @@ static int spi_nor_write(struct mtd_info *mtd, loff_t to, size_t len, if (ret) goto write_err; - ret = spi_nor_write_data(nor, addr, page_remain, buf + i); + if (nor->write_proto == SNOR_PROTO_8_8_8_DTR) + ret = spi_nor_octal_dtr_write(nor, addr, page_remain, + buf + i); + else + ret = spi_nor_write_data(nor, addr, page_remain, + buf + i); if (ret < 0) goto write_err; written = ret; |