From 5fb4e8d7287ac8fcb33aae8b1e9e22c5a3c392bd Mon Sep 17 00:00:00 2001 From: Jonas Gorski <jonas.gorski@gmail.com> Date: Thu, 10 Nov 2011 17:33:40 +0100 Subject: [PATCH 51/79] MTD: DEVICES: m25p80: add support for limiting reads Signed-off-by: Jonas Gorski <jonas.gorski@gmail.com> --- drivers/mtd/devices/m25p80.c | 29 +++++++++++++++++++++++++++-- include/linux/spi/flash.h | 4 ++++ 2 files changed, 31 insertions(+), 2 deletions(-) --- a/drivers/mtd/devices/m25p80.c +++ b/drivers/mtd/devices/m25p80.c @@ -93,6 +93,7 @@ struct m25p { u8 erase_opcode; u8 *command; bool fast_read; + int max_transfer_len; }; static inline struct m25p *mtd_to_m25p(struct mtd_info *mtd) @@ -337,10 +338,9 @@ static int m25p80_erase(struct mtd_info * Read an address range from the flash chip. The address range * may be any size provided it is within the physical boundaries. */ -static int m25p80_read(struct mtd_info *mtd, loff_t from, size_t len, +static int __m25p80_read(struct m25p *flash, loff_t from, size_t len, size_t *retlen, u_char *buf) { - struct m25p *flash = mtd_to_m25p(mtd); struct spi_transfer t[2]; struct spi_message m; uint8_t opcode; @@ -392,6 +392,28 @@ static int m25p80_read(struct mtd_info * return 0; } +static int m25p80_read(struct mtd_info *mtd, loff_t from, size_t len, + size_t *retlen, u_char *buf) +{ + struct m25p *flash = mtd_to_m25p(mtd); + size_t off; + size_t read_len = flash->max_transfer_len; + size_t part_len; + int ret = 0; + + if (!read_len) + return __m25p80_read(flash, from, len, retlen, buf); + + *retlen = 0; + + for (off = 0; off < len && !ret; off += read_len) { + ret = __m25p80_read(flash, from + off, min(len - off, read_len), + &part_len, buf + off); + *retlen += part_len; + } + + return ret; +} /* * Write an address range to the flash chip. Data must be written in * FLASH_PAGESIZE chunks. The address range may be any size provided @@ -889,6 +911,9 @@ static int m25p_probe(struct spi_device return -ENOMEM; } + if (data) + flash->max_transfer_len = data->max_transfer_len; + flash->spi = spi; mutex_init(&flash->lock); dev_set_drvdata(&spi->dev, flash); --- a/include/linux/spi/flash.h +++ b/include/linux/spi/flash.h @@ -13,6 +13,8 @@ struct mtd_part_parser_data; * @part_probe_types: optional list of MTD parser names to use for * partitioning * + * @max_transfer_len: option maximum read/write length limitation for + * SPI controllers not able to transfer any length commands. * Board init code (in arch/.../mach-xxx/board-yyy.c files) can * provide information about SPI flash parts (such as DataFlash) to * help set up the device and its appropriate default partitioning. @@ -28,6 +30,8 @@ struct flash_platform_data { char *type; const char **part_probe_types; + + unsigned int max_transfer_len; /* we'll likely add more ... use JEDEC IDs, etc */ };