OMAP NAND driver support multiple ECC scheme, which can used in following
different flavours, depending on in-build Hardware engines supported by SoC.
+---------------------------------------+---------------+---------------+
| ECC scheme |ECC calculation|Error detection|
+---------------------------------------+---------------+---------------+
|OMAP_ECC_HAMMING_CODE_HW |H/W (GPMC) |S/W |
+---------------------------------------+---------------+---------------+
|OMAP_ECC_BCH8_CODE_HW_DETECTION_SW |H/W (GPMC) |S/W |
|(requires CONFIG_MTD_NAND_ECC_BCH) | | |
+---------------------------------------+---------------+---------------+
|OMAP_ECC_BCH8_CODE_HW |H/W (GPMC) |H/W (ELM) |
|(requires CONFIG_MTD_NAND_OMAP_BCH && | | |
| ti,elm-id in DT) | | |
+---------------------------------------+---------------+---------------+
To optimize footprint of omap2-nand driver, selection of some ECC schemes
also require enabling following Kconfigs, in addition to setting appropriate
DT bindings
- Kconfig:CONFIG_MTD_NAND_ECC_BCH enables S/W based BCH ECC algorithm
- Kconfig:CONFIG_MTD_NAND_OMAP_BCH enables H/W based BCH ECC algorithm
This patch
- updates DT binding for selection of ecc-scheme
- updates DT binding for detection of ELM h/w engine
- removes following obselete ECC schemes
OMAP_ECC_HAMMING_CODE_DEFAULT (S/W based 1-bit Hamming ECC)
OMAP_ECC_HAMMING_CODE_HW_ROMCODE (H/W based 1-bit Hamming ECC scheme)
- updates DT binding documentation for mtd/gpmc-nand
Signed-off-by: Pekon Gupta <pekon@xxxxxx>
---
.../devicetree/bindings/mtd/gpmc-nand.txt | 14 +++----
arch/arm/mach-omap2/board-flash.c | 2 +-
arch/arm/mach-omap2/gpmc.c | 47 +++++++++++++++-------
include/linux/platform_data/mtd-nand-omap2.h | 23 +++++++----
4 files changed, 56 insertions(+), 30 deletions(-)
diff --git a/Documentation/devicetree/bindings/mtd/gpmc-nand.txt b/Documentation/devicetree/bindings/mtd/gpmc-nand.txt
index df338cb..958e5d5 100644
--- a/Documentation/devicetree/bindings/mtd/gpmc-nand.txt
+++ b/Documentation/devicetree/bindings/mtd/gpmc-nand.txt
@@ -21,11 +21,8 @@ Optional properties:
is wired that way. If not specified, a bus
width of 8 is assumed.
- - ti,nand-ecc-opt: A string setting the ECC layout to use. One of:
-
- "sw" Software method (default)
- "hw" Hardware method
- "hw-romcode" gpmc hamming mode method & romcode layout
+ - ti,nand-ecc-scheme: A string setting the ECC layout to use. One of:
+ "ham1" 1-bit Hamming ecc code
"bch4" 4-bit BCH ecc code
"bch8" 8-bit BCH ecc code
@@ -36,8 +33,11 @@ Optional properties:
"prefetch-dma" Prefetch enabled sDMA mode
"prefetch-irq" Prefetch enabled irq mode
- - elm_id: Specifies elm device node. This is required to support BCH
- error correction using ELM module.
+ - ti,elm-id: Specifies pHandle of the ELM devicetree node.
+ ELM is an on-chip hardware engine on TI SoC which is used for
+ locating ECC errors for BCHx algorithms. SoC devices which have
+ ELM hardware engines should specify this device node in .dtsi
+ Using ELM for ECC error correction frees some CPU cycles.
For inline partiton table parsing (optional):
diff --git a/arch/arm/mach-omap2/board-flash.c b/arch/arm/mach-omap2/board-flash.c
index fc20a61..ac82512 100644
--- a/arch/arm/mach-omap2/board-flash.c
+++ b/arch/arm/mach-omap2/board-flash.c
@@ -142,7 +142,7 @@ __init board_nand_init(struct mtd_partition *nand_parts, u8 nr_parts, u8 cs,
board_nand_data.nr_parts = nr_parts;
board_nand_data.devsize = nand_type;
- board_nand_data.ecc_opt = OMAP_ECC_HAMMING_CODE_DEFAULT;
+ board_nand_data.ecc_opt = OMAP_ECC_BCH8_CODE_HW;
gpmc_nand_init(&board_nand_data, gpmc_t);
}
#endif /* CONFIG_MTD_NAND_OMAP2 || CONFIG_MTD_NAND_OMAP2_MODULE */
diff --git a/arch/arm/mach-omap2/gpmc.c b/arch/arm/mach-omap2/gpmc.c
index 9f4795a..6409884 100644
--- a/arch/arm/mach-omap2/gpmc.c
+++ b/arch/arm/mach-omap2/gpmc.c
@@ -1340,15 +1340,6 @@ static void __maybe_unused gpmc_read_timings_dt(struct device_node *np,
}
#ifdef CONFIG_MTD_NAND
-
-static const char * const nand_ecc_opts[] = {
- [OMAP_ECC_HAMMING_CODE_DEFAULT] = "sw",
- [OMAP_ECC_HAMMING_CODE_HW] = "hw",
- [OMAP_ECC_HAMMING_CODE_HW_ROMCODE] = "hw-romcode",
- [OMAP_ECC_BCH4_CODE_HW] = "bch4",
- [OMAP_ECC_BCH8_CODE_HW] = "bch8",
-};
-
static const char * const nand_xfer_types[] = {
[NAND_OMAP_PREFETCH_POLLED] = "prefetch-polled",
[NAND_OMAP_POLLED] = "polled",
@@ -1363,6 +1354,8 @@ static int gpmc_probe_nand_child(struct platform_device *pdev,
const char *s;
struct gpmc_timings gpmc_t;
struct omap_nand_platform_data *gpmc_nand_data;
+ const __be32 *parp;
+ int lenp;
if (of_property_read_u32(child, "reg", &val) < 0) {
dev_err(&pdev->dev, "%s has no 'reg' property\n",
@@ -1378,12 +1371,36 @@ static int gpmc_probe_nand_child(struct platform_device *pdev,
gpmc_nand_data->cs = val;
gpmc_nand_data->of_node = child;
- if (!of_property_read_string(child, "ti,nand-ecc-opt", &s))
- for (val = 0; val < ARRAY_SIZE(nand_ecc_opts); val++)
- if (!strcasecmp(s, nand_ecc_opts[val])) {
- gpmc_nand_data->ecc_opt = val;
- break;
- }
+ /* Detect availability of ELM module */
+ parp = of_get_property(child, "ti,elm-id", &lenp);
+ if ((parp == NULL) && (lenp != (sizeof(void *) * 2))) {
+ pr_warn("%s: ti,elm-id property not found\n", __func__);
+ gpmc_nand_data->elm_of_node = NULL;
+ } else {
+ gpmc_nand_data->elm_of_node =
+ of_find_node_by_phandle(be32_to_cpup(parp));
+ }
+ /* select NAND ecc-scheme */
+ if (of_property_read_string(child, "ti,nand-ecc-scheme", &s)) {
+ pr_err("%s: valid ti,nand-ecc-scheme not found\n", __func__);
+ return -ENODEV;
+ }
+ if (!strcmp(s, "ham1"))
+ gpmc_nand_data->ecc_opt = OMAP_ECC_HAMMING_CODE_HW;
+ else if (!strcmp(s, "bch4"))
+ if (gpmc_nand_data->elm_of_node)
+ gpmc_nand_data->ecc_opt = OMAP_ECC_BCH4_CODE_HW;
+ else
+ gpmc_nand_data->ecc_opt =
+ OMAP_ECC_BCH4_CODE_HW_DETECTION_SW;
+ else if (!strcmp(s, "bch8"))
+ if (gpmc_nand_data->elm_of_node)
+ gpmc_nand_data->ecc_opt = OMAP_ECC_BCH8_CODE_HW;
+ else
+ gpmc_nand_data->ecc_opt =
+ OMAP_ECC_BCH8_CODE_HW_DETECTION_SW;
+ else
+ pr_err("%s: ti,ecc-scheme: invalid property value\n", __func__);
if (!of_property_read_string(child, "ti,nand-xfer-type", &s))
for (val = 0; val < ARRAY_SIZE(nand_xfer_types); val++)
diff --git a/include/linux/platform_data/mtd-nand-omap2.h b/include/linux/platform_data/mtd-nand-omap2.h
index 6bf9ef4..b4c2c5a 100644
--- a/include/linux/platform_data/mtd-nand-omap2.h
+++ b/include/linux/platform_data/mtd-nand-omap2.h
@@ -23,13 +23,21 @@ enum nand_io {
};
enum omap_ecc {
- /* 1-bit ecc: stored at end of spare area */
- OMAP_ECC_HAMMING_CODE_DEFAULT = 0, /* Default, s/w method */
- OMAP_ECC_HAMMING_CODE_HW, /* gpmc to detect the error */
- /* 1-bit ecc: stored at beginning of spare area as romcode */
- OMAP_ECC_HAMMING_CODE_HW_ROMCODE, /* gpmc method & romcode layout */
- OMAP_ECC_BCH4_CODE_HW, /* 4-bit BCH ecc code */
- OMAP_ECC_BCH8_CODE_HW, /* 8-bit BCH ecc code */
+ /* 1-bit ECC calculation by Software, Error detection by Software */
+ OMAP_ECC_HAMMING_CODE_DEFAULT = 0,
+ /* 1-bit ECC calculation by GPMC, Error detection by Software */
+ OMAP_ECC_HAMMING_CODE_HW,
+ /* 1-bit ECC calculation by GPMC, Error detection by Software */
+ /* ECC layout compatible to legacy ROMCODE. */
+ OMAP_ECC_HAMMING_CODE_HW_ROMCODE,
+ /* 4-bit ECC calculation by GPMC, Error detection by Software */
+ OMAP_ECC_BCH4_CODE_HW_DETECTION_SW,
+ /* 4-bit ECC calculation by GPMC, Error detection by ELM */
+ OMAP_ECC_BCH4_CODE_HW,
+ /* 8-bit ECC calculation by GPMC, Error detection by Software */
+ OMAP_ECC_BCH8_CODE_HW_DETECTION_SW,
+ /* 8-bit ECC calculation by GPMC, Error detection by ELM */
+ OMAP_ECC_BCH8_CODE_HW,
};
struct gpmc_nand_regs {
@@ -63,5 +71,6 @@ struct omap_nand_platform_data {
/* for passing the partitions */
struct device_node *of_node;
+ struct device_node *elm_of_node;
};
#endif
--
1.8.1
--
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