From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bear.ext.ti.com ([192.94.94.41]) by merlin.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1WLuQb-0008AF-KD for linux-mtd@lists.infradead.org; Fri, 07 Mar 2014 13:03:06 +0000 From: Pekon Gupta To: Brian Norris Subject: [PATCH v6 1/4] mtd: devices: elm: check for hardware engine's design constrains Date: Fri, 7 Mar 2014 18:32:21 +0530 Message-ID: <1394197344-9468-2-git-send-email-pekon@ti.com> In-Reply-To: <1394197344-9468-1-git-send-email-pekon@ti.com> References: <1394197344-9468-1-git-send-email-pekon@ti.com> MIME-Version: 1.0 Content-Type: text/plain Cc: avinashphilipk@gmail.com, Felipe Balbi , linux-mtd , Pekon Gupta , Ezequiel Garcia , Stefan Roese List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , ELM hardware engine is used by BCH ecc-schemes for detecting and locating ECC errors. This patch adds following checks as per ELM design constrains: - ELM internal buffers are of 1K, So it cannot process data with ecc-step-size > 1K. - ELM engine can execute upto maximum of 8 threads in parallel, So in *page-mode* (when complete page is processed in single iteration), ELM cannot support ecc-steps > 8. Signed-off-by: Pekon Gupta --- drivers/mtd/devices/elm.c | 19 ++++++++++++++++++- drivers/mtd/nand/omap2.c | 9 ++++++--- include/linux/platform_data/elm.h | 3 ++- 3 files changed, 26 insertions(+), 5 deletions(-) diff --git a/drivers/mtd/devices/elm.c b/drivers/mtd/devices/elm.c index f160d2c..7fda50f 100644 --- a/drivers/mtd/devices/elm.c +++ b/drivers/mtd/devices/elm.c @@ -84,6 +84,9 @@ struct elm_info { struct list_head list; enum bch_ecc bch_type; struct elm_registers elm_regs; + int ecc_steps; + int ecc_step_size; + int ecc_step_bytes; }; static LIST_HEAD(elm_devices); @@ -103,7 +106,8 @@ static u32 elm_read_reg(struct elm_info *info, int offset) * @dev: ELM device * @bch_type: Type of BCH ecc */ -int elm_config(struct device *dev, enum bch_ecc bch_type) +int elm_config(struct device *dev, enum bch_ecc bch_type, + int ecc_steps, int ecc_step_size, int ecc_step_bytes) { u32 reg_val; struct elm_info *info = dev_get_drvdata(dev); @@ -112,10 +116,23 @@ int elm_config(struct device *dev, enum bch_ecc bch_type) dev_err(dev, "Unable to configure elm - device not probed?\n"); return -ENODEV; } + /* ELM cannot detect ECC errors for chunks > 1KB */ + if (ecc_step_size > (ELM_ECC_SIZE/2 + 1)) { + pr_err("unsupported config ecc-size=%d", ecc_step_size); + return -EINVAL; + } + /* ELM support 8 error syndrome process */ + if (ecc_steps > ERROR_VECTOR_MAX) { + pr_err("unsupported config ecc-step=%d", ecc_steps); + return -EINVAL; + } reg_val = (bch_type & ECC_BCH_LEVEL_MASK) | (ELM_ECC_SIZE << 16); elm_write_reg(info, ELM_LOCATION_CONFIG, reg_val); info->bch_type = bch_type; + info->ecc_steps = ecc_steps; + info->ecc_step_size = ecc_step_size; + info->ecc_step_bytes = ecc_step_bytes; return 0; } diff --git a/drivers/mtd/nand/omap2.c b/drivers/mtd/nand/omap2.c index 5ce2097..369aee7 100644 --- a/drivers/mtd/nand/omap2.c +++ b/drivers/mtd/nand/omap2.c @@ -1546,6 +1546,8 @@ static int is_elm_present(struct omap_nand_info *info, struct device_node *elm_node, enum bch_ecc bch_type) { struct platform_device *pdev; + struct nand_ecc_ctrl *ecc = &info->nand.ecc; + int err = 0; /* check whether elm-id is passed via DT */ if (!elm_node) { pr_err("nand: error: ELM DT node not found\n"); @@ -1559,9 +1561,10 @@ static int is_elm_present(struct omap_nand_info *info, } /* ELM module available, now configure it */ info->elm_dev = &pdev->dev; - if (elm_config(info->elm_dev, bch_type)) - return -ENODEV; - return 0; + err = elm_config(info->elm_dev, bch_type, + (info->mtd.writesize / ecc->size), ecc->size, ecc->bytes); + + return err; } #endif /* CONFIG_MTD_NAND_ECC_BCH */ diff --git a/include/linux/platform_data/elm.h b/include/linux/platform_data/elm.h index bf0a83b..b824ff3 100644 --- a/include/linux/platform_data/elm.h +++ b/include/linux/platform_data/elm.h @@ -50,5 +50,6 @@ struct elm_errorvec { void elm_decode_bch_error_page(struct device *dev, u8 *ecc_calc, struct elm_errorvec *err_vec); -int elm_config(struct device *dev, enum bch_ecc bch_type); +int elm_config(struct device *dev, enum bch_ecc bch_type, + int ecc_steps, int ecc_step_size, int ecc_step_bytes); #endif /* __ELM_H */ -- 1.8.5.1.163.gd7aced9