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_HAM1_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 error detection done in software
- Kconfig:CONFIG_MTD_NAND_OMAP_BCH error detection done by h/w engine
DT binding updates in this patch are:
- ti,elm-id: replaces elm_id
- ti,nand-ecc-opts: supported values ham1, bch4, and bch8
selection of h/w or s/w implementation depends on ti,elm-id
Signed-off-by: Pekon Gupta <pekon@xxxxxx>
---
.../devicetree/bindings/mtd/gpmc-nand.txt | 8 +++-
arch/arm/mach-omap2/gpmc.c | 47 ++++++++++++++++------
include/linux/platform_data/mtd-nand-omap2.h | 14 +++++--
3 files changed, 52 insertions(+), 17 deletions(-)
diff --git a/Documentation/devicetree/bindings/mtd/gpmc-nand.txt b/Documentation/devicetree/bindings/mtd/gpmc-nand.txt
index 25ee232..7785666 100644
--- a/Documentation/devicetree/bindings/mtd/gpmc-nand.txt
+++ b/Documentation/devicetree/bindings/mtd/gpmc-nand.txt
@@ -36,8 +36,12 @@ 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.
+ - elm_id: <deprecated> use "ti,elm-id" instead
+ - 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/gpmc.c b/arch/arm/mach-omap2/gpmc.c
index 1c45b72..5a607fa 100644
--- a/arch/arm/mach-omap2/gpmc.c
+++ b/arch/arm/mach-omap2/gpmc.c
@@ -1341,12 +1341,6 @@ 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_HAM1_CODE_HW] = "ham1",
- [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",
@@ -1361,6 +1355,8 @@ 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 *phandle;
+ int lenp;
if (of_property_read_u32(child, "reg", &val) < 0) {
dev_err(&pdev->dev, "%s has no 'reg' property\n",
@@ -1376,12 +1372,39 @@ 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 */
+ phandle = of_get_property(child, "ti,elm-id", &lenp);
+ if ((phandle == NULL) || (lenp != sizeof(void *))) {
+ 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(phandle));
+ }
+ /* select NAND ecc-opt */
+ if (of_property_read_string(child, "ti,nand-ecc-opt", &s)) {
+ pr_err("%s: ti,nand-ecc-opt not found\n", __func__);
+ return -ENODEV;
+ }
+ if (!strcmp(s, "ham1"))
+ gpmc_nand_data->ecc_opt =
+ OMAP_ECC_HAM1_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,nand-ecc-opt invalid 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 cb5a54a..4da5bfa 100644
--- a/include/linux/platform_data/mtd-nand-omap2.h
+++ b/include/linux/platform_data/mtd-nand-omap2.h
@@ -23,9 +23,16 @@ enum nand_io {
};
enum omap_ecc {
- OMAP_ECC_HAM1_CODE_HW = 0, /* 1-bit Hamming ecc code */
- 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 GPMC, Error detection by Software */
+ OMAP_ECC_HAM1_CODE_HW = 0,
+ /* 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 {
@@ -59,5 +66,6 @@ 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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