Re: [PATCH V3] Add support for flag status register on Micron chips.

Huang Shijie
2014-04-25T02:32:18Z

On Tue, Apr 22, 2014 at 09:03:16AM -0500, Graham Moore wrote:
> Some new Micron flash chips require reading the flag
> status register to determine when operations have completed.
>
> Furthermore, chips with multi-die stacks of the 65nm 256Mb QSPI also
> require reading the status register before reading the flag status register.
>
> This patch adds support for the flag status register in the n25q512ax3 and n25q00
> Micron QSPI flash chips.
>
> Signed-off-by: Graham Moore <grmoore@altera.com>
> ---
> V3:
> Rebase to l2-mtd spinor branch.
> V2:
> Remove leading underscore in function names.
> Remove type cast in dev_err call and use the proper format
> specifier instead.
> ---
> drivers/mtd/spi-nor/spi-nor.c | 51 +++++++++++++++++++++++++++++++++++++++++
> include/linux/mtd/spi-nor.h | 4 ++++
> 2 files changed, 55 insertions(+)
>
> diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
> index d6f44d5..24b84d8 100644
> --- a/drivers/mtd/spi-nor/spi-nor.c
> +++ b/drivers/mtd/spi-nor/spi-nor.c
> @@ -48,6 +48,25 @@ static int read_sr(struct spi_nor *nor)
> }
>
> /*
> + * Read the flag status register, returning its value in the location
> + * Return the status register value.
> + * Returns negative if error occurred.
> + */
> +static int read_fsr(struct spi_nor *nor)
> +{
> + int ret;
> + u8 val;
> +
> + ret = nor->read_reg(nor, SPINOR_OP_RDFSR, &val, 1);
> + if (ret < 0) {
> + pr_err("error %d reading FSR\n", ret);
> + return ret;
> + }
> +
> + return val;
> +}
> +
> +/*
> * Read configuration register, returning its value in the
> * location. Return the configuration register value.
> * Returns negative if error occured.
> @@ -165,6 +184,32 @@ static int spi_nor_wait_till_ready(struct spi_nor *nor)
> return -ETIMEDOUT;
> }
>
> +static int spi_nor_wait_till_fsr_ready(struct spi_nor *nor)
> +{
> + unsigned long deadline;
> + int sr;
> + int fsr;
> +
> + deadline = jiffies + MAX_READY_WAIT_JIFFIES;
> +
> + do {
> + cond_resched();
> +
> + sr = read_sr(nor);
> + if (sr < 0)
> + break;
> + else if (!(sr & SR_WIP)) {
> + fsr = read_fsr(nor);
> + if (fsr < 0)
> + break;
> + if (fsr & FSR_READY)
> + return 0;
> + }
> + } while (!time_after_eq(jiffies, deadline));
> +
> + return -ETIMEDOUT;
> +}
> +
> /*
> * Service routine to read status register until ready, or timeout occurs.
> * Returns non-zero if error.
> @@ -402,6 +447,7 @@ struct flash_info {
> #define SECT_4K_PMC 0x10 /* SPINOR_OP_BE_4K_PMC works uniformly */
> #define SPI_NOR_DUAL_READ 0x20 /* Flash supports Dual Read */
> #define SPI_NOR_QUAD_READ 0x40 /* Flash supports Quad Read */
> +#define USE_FSR 0x80 /* use flag status register */
> };
>
> #define INFO(_jedec_id, _ext_id, _sector_size, _n_sectors, _flags) \
> @@ -488,6 +534,8 @@ const struct spi_device_id spi_nor_ids[] = {
> { "n25q128a13", INFO(0x20ba18, 0, 64 * 1024, 256, 0) },
> { "n25q256a", INFO(0x20ba19, 0, 64 * 1024, 512, SECT_4K) },
> { "n25q512a", INFO(0x20bb20, 0, 64 * 1024, 1024, SECT_4K) },
> + { "n25q512ax3", INFO(0x20ba20, 0, 64 * 1024, 1024, USE_FSR) },
> + { "n25q00", INFO(0x20ba21, 0, 64 * 1024, 2048, USE_FSR) },
>
> /* PMC */
> { "pm25lv512", INFO(0, 0, 32 * 1024, 2, SECT_4K_PMC) },
> @@ -965,6 +1013,9 @@ int spi_nor_scan(struct spi_nor *nor, const struct spi_device_id *id,
> else
> mtd->_write = spi_nor_write;
>
> + if (info->flags & USE_FSR)
> + nor->wait_till_ready = spi_nor_wait_till_fsr_ready;
> +
the drivers may fills this hook itself, so the code should like this:
--------------------------------------------------
if ((info->flags & USE_FSR) &&
nor->wait_till_ready == spi_nor_wait_till_fsr_ready)
nor->wait_till_ready = spi_nor_wait_till_fsr_ready;
--------------------------------------------------

thanks
Huang Shijie