[Skiboot] [RFC PATCH 2/2] libflash/file: add file abstraction for libflash

[Alistair Popple]

Hi Cyril,

Is libflash providing any useful functionality here? Or are you creating this backend just 
to use the libffs API?

Regards,

Alistair

On Thu, 19 Mar 2015 18:18:21 Cyril Bur wrote:
> The functionality provided by libflash and libffs are useful and it would be
> good to use them on dumps of flash or even access flash from userland
> through MTD devices which are presented as files.
> 
> Signed-off-by: Cyril Bur <cyril.bur at au1.ibm.com>
> ---
>  libflash/file_flash.c    | 224
> +++++++++++++++++++++++++++++++++++++++++++++++ libflash/file_flash.h    | 
> 11 +++
>  libflash/libflash-priv.h |   2 +
>  libflash/libflash.c      |   1 +
>  4 files changed, 238 insertions(+)
>  create mode 100644 libflash/file_flash.c
>  create mode 100644 libflash/file_flash.h
> 
> diff --git a/libflash/file_flash.c b/libflash/file_flash.c
> new file mode 100644
> index 0000000..d902672
> --- /dev/null
> +++ b/libflash/file_flash.c
> @@ -0,0 +1,224 @@
> +#include <unistd.h>
> +#include <sys/types.h>
> +#include <sys/stat.h>
> +#include <stdbool.h>
> +#include <stdlib.h>
> +#include <sys/ioctl.h>
> +#include <sys/mman.h>
> +#include <string.h>
> +
> +#include <mtd/mtd-abi.h>
> +
> +#include "file_flash.h"
> +
> +/* The caller is going to have to supply this */
> +struct file_flash_priv {
> +	int fd;
> +};
> +
> +/*
> + * Unfortunately not all file descriptors are created equal...
> + * Here we check to see if the file descriptor is to an MTD device, in
> which + * case we have to get the size of it differently.
> + */
> +int file_setup(struct spi_flash_ctrl *ctrl, uint32_t *tsize)
> +{
> +	struct mtd_info_user mtd_info;
> +	struct file_flash_priv *file_flash_data;
> +	struct stat sbuf;
> +
> +	if (!ctrl || !ctrl->priv)
> +		return -1;
> +
> +	file_flash_data = (struct file_flash_priv *)ctrl->priv;
> +
> +	if (fstat(file_flash_data->fd, &sbuf) == -1)
> +		return -1;
> +
> +	if (S_ISCHR(sbuf.st_mode)) {
> +		if (ioctl(file_flash_data->fd, MEMGETINFO, &mtd_info) == 
-1)
> +			return -1;
> +
> +		ctrl->finfo->size = mtd_info.size;
> +
> +	} else if (S_ISREG(sbuf.st_mode)) {
> +		ctrl->finfo->size = sbuf.st_size;
> +
> +	} else {
> +		/* Not going to be able to work with anything else */
> +		return -1;
> +	}
> +
> +	if (tsize)
> +		*tsize = ctrl->finfo->size;
> +
> +	return 0;
> +}
> +
> +int file_set4b(struct spi_flash_ctrl *ctrl, bool enable)
> +{
> +	/* Always report success no matter what, this isn't relevent for files */
> +	return 0;
> +}
> +
> +int file_chipid(struct spi_flash_ctrl *ctrl, uint8_t *id_buf,
> +		uint32_t *id_size)
> +{
> +	if (!ctrl || !ctrl->priv || !id_size || *id_size < 3)
> +		return -1;
> +
> +	id_buf[0] = 'M';
> +	id_buf[1] = 'T';
> +	id_buf[2] = 'D';
> +
> +	*id_size = 3;
> +	return 0;
> +}
> +
> +int file_read(struct spi_flash_ctrl *ctrl, uint32_t addr, void *buf,
> +		uint32_t size)
> +{
> +	int rc;
> +	struct file_flash_priv *file_flash_data;
> +
> +	if (!ctrl || !ctrl->priv)
> +		return -1;
> +
> +	file_flash_data = (struct file_flash_priv *)ctrl->priv;
> +
> +	rc = lseek(file_flash_data->fd, addr, SEEK_SET);
> +	if ((off_t )rc == (off_t )-1)
> +		return -1;
> +
> +	rc = read(file_flash_data->fd, buf, size);
> +	if (rc == -1)
> +		return -1;
> +	/* TODO Perhaps deal with short reads */
> +
> +	return 0;
> +}
> +
> +int file_write(struct spi_flash_ctrl *ctrl, uint32_t addr,
> +		const void *buf, uint32_t size)
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