[PATCH 3/4] ARM: OMAP2: gpmc: Add support for BCH ECC scheme
Philip, Avinash
avinashphilip at ti.com
Wed Oct 3 10:29:48 EDT 2012
Add support for BCH ECC scheme to gpmc driver and also enabling multi
sector read/write. This helps in doing single shot NAND page read and
write.
ECC engine configurations
BCH 4 bit support
1. write => ECC engine configured in wrap mode 6 and with ecc_size0 as 32.
2. read => ECC engine configured in wrap mode 1 and with ecc_size0 as
13 and ecc_size1 as 1.
BCH 8 bit support
1. write => ECC engine configured in wrap mode 6 and with ecc_size0 as 32.
2. read => ECC engine configured in wrap mode 1 and with ecc_size0 as
26 and ecc_size1 as 2.
Note: For BCH8 ECC bytes set to 14 to make compatible with RBL.
Signed-off-by: Philip, Avinash <avinashphilip at ti.com>
---
:100644 100644 72428bd... c9bc3cf... M arch/arm/mach-omap2/gpmc.c
:100644 100644 2e6e259... c916510... M arch/arm/plat-omap/include/plat/gpmc.h
arch/arm/mach-omap2/gpmc.c | 120 +++++++++++++++++++++++++++++---
arch/arm/plat-omap/include/plat/gpmc.h | 1 +
2 files changed, 112 insertions(+), 9 deletions(-)
diff --git a/arch/arm/mach-omap2/gpmc.c b/arch/arm/mach-omap2/gpmc.c
index 72428bd..c9bc3cf 100644
--- a/arch/arm/mach-omap2/gpmc.c
+++ b/arch/arm/mach-omap2/gpmc.c
@@ -24,6 +24,7 @@
#include <linux/io.h>
#include <linux/module.h>
#include <linux/interrupt.h>
+#include <linux/mtd/nand.h>
#include <asm/mach-types.h>
#include <plat/gpmc.h>
@@ -83,6 +84,18 @@
#define ENABLE_PREFETCH (0x1 << 7)
#define DMA_MPU_MODE 2
+/* GPMC ecc engine settings for read */
+#define BCH_WRAPMODE_1 1 /* BCH wrap mode 6 */
+#define BCH8R_ECC_SIZE0 0x1a /* ecc_size0 = 26 */
+#define BCH8R_ECC_SIZE1 0x2 /* ecc_size1 = 2 */
+#define BCH4R_ECC_SIZE0 0xd /* ecc_size0 = 13 */
+#define BCH4R_ECC_SIZE1 0x1 /* ecc_size1 = 1 4bit padding in BCH4 */
+
+/* GPMC ecc engine settings for write */
+#define BCH_WRAPMODE_6 6 /* BCH wrap mode 6 */
+#define BCH_ECC_SIZE0 0x0 /* ecc_size0 = 0, no oob protection */
+#define BCH_ECC_SIZE1 0x20 /* ecc_size1 = 32 */
+
/* XXX: Only NAND irq has been considered,currently these are the only ones used
*/
#define GPMC_NR_IRQ 2
@@ -1119,7 +1132,8 @@ EXPORT_SYMBOL_GPL(gpmc_init_hwecc_bch);
int gpmc_enable_hwecc_bch(int cs, int mode, int dev_width, int nsectors,
int nerrors)
{
- unsigned int val;
+ unsigned int val, wr_mode;
+ unsigned int ecc_size1, ecc_size0;
/* check if ecc module is in use */
if (gpmc_ecc_used != -EINVAL)
@@ -1130,18 +1144,35 @@ int gpmc_enable_hwecc_bch(int cs, int mode, int dev_width, int nsectors,
/* clear ecc and enable bits */
gpmc_write_reg(GPMC_ECC_CONTROL, 0x1);
- /*
- * When using BCH, sector size is hardcoded to 512 bytes.
- * Here we are using wrapping mode 6 both for reading and writing, with:
- * size0 = 0 (no additional protected byte in spare area)
- * size1 = 32 (skip 32 nibbles = 16 bytes per sector in spare area)
- */
- gpmc_write_reg(GPMC_ECC_SIZE_CONFIG, (32 << 22) | (0 << 12));
+ /* When using BCH, sector size is hard coded to 512 bytes. */
+ if ((mode == NAND_ECC_READ) && (nsectors != 1)) {
+ /*
+ * Here we are using wrapping mode 1 for reading, for
+ * supporting multi sector reading.
+ * Read mode, ECC engine enabled for valid ecc_size0 nibbles
+ * & disabled for ecc_size1 nibbles.
+ */
+ ecc_size0 = (nerrors == 8) ? BCH8R_ECC_SIZE0 : BCH4R_ECC_SIZE0;
+ ecc_size1 = (nerrors == 8) ? BCH8R_ECC_SIZE1 : BCH4R_ECC_SIZE1;
+ wr_mode = BCH_WRAPMODE_1;
+ } else {
+ /*
+ * Here we are using wrapping mode 6 for writing,
+ * ECC engine enabled for valid ecc_size0 nibbles
+ * & disabled for ecc_size1 nibbles.
+ */
+ ecc_size0 = BCH_ECC_SIZE0;
+ ecc_size1 = BCH_ECC_SIZE1;
+ wr_mode = BCH_WRAPMODE_6;
+ }
+
+ gpmc_write_reg(GPMC_ECC_SIZE_CONFIG, (ecc_size1 << 22) |
+ (ecc_size0 << 12));
/* BCH configuration */
val = ((1 << 16) | /* enable BCH */
(((nerrors == 8) ? 1 : 0) << 12) | /* 8 or 4 bits */
- (0x06 << 8) | /* wrap mode = 6 */
+ (wr_mode << 8) | /* wrap mode = 6 or 1 */
(dev_width << 7) | /* bus width */
(((nsectors-1) & 0x7) << 4) | /* number of sectors */
(cs << 1) | /* ECC CS */
@@ -1154,6 +1185,77 @@ int gpmc_enable_hwecc_bch(int cs, int mode, int dev_width, int nsectors,
EXPORT_SYMBOL_GPL(gpmc_enable_hwecc_bch);
/**
+ * gpmc_calculate_ecc_bch - Generate ecc bytes per block of 512 data bytes for entire page
+ * @cs: chip select number
+ * @dat: The pointer to data on which ECC is computed
+ * @ecc: The ECC output buffer
+ */
+int gpmc_calculate_ecc_bch(int cs, const u_char *dat, u_char *ecc)
+{
+ int i, eccbchtsel;
+ u32 nsectors, reg, bch_val1, bch_val2, bch_val3, bch_val4;
+
+ if (gpmc_ecc_used != cs)
+ return -EINVAL;
+
+ /* read number of sectors for ecc to be calculated */
+ nsectors = ((gpmc_read_reg(GPMC_ECC_CONFIG) >> 4) & 0x7) + 1;
+ /*
+ * find BCH scheme used
+ * 0 -> BCH4
+ * 1 -> BCH8
+ */
+ eccbchtsel = ((gpmc_read_reg(GPMC_ECC_CONFIG) >> 12) & 0x3);
+
+ /* update ecc bytes for entire page */
+ for (i = 0; i < nsectors; i++) {
+
+ reg = GPMC_ECC_BCH_RESULT_0 + 16 * i;
+
+ /* Read hw-computed remainder */
+ bch_val1 = gpmc_read_reg(reg + 0);
+ bch_val2 = gpmc_read_reg(reg + 4);
+ if (eccbchtsel) {
+ bch_val3 = gpmc_read_reg(reg + 8);
+ bch_val4 = gpmc_read_reg(reg + 12);
+ }
+
+ if (eccbchtsel) {
+ /* BCH8 ecc scheme */
+ *ecc++ = (bch_val4 & 0xFF);
+ *ecc++ = ((bch_val3 >> 24) & 0xFF);
+ *ecc++ = ((bch_val3 >> 16) & 0xFF);
+ *ecc++ = ((bch_val3 >> 8) & 0xFF);
+ *ecc++ = (bch_val3 & 0xFF);
+ *ecc++ = ((bch_val2 >> 24) & 0xFF);
+ *ecc++ = ((bch_val2 >> 16) & 0xFF);
+ *ecc++ = ((bch_val2 >> 8) & 0xFF);
+ *ecc++ = (bch_val2 & 0xFF);
+ *ecc++ = ((bch_val1 >> 24) & 0xFF);
+ *ecc++ = ((bch_val1 >> 16) & 0xFF);
+ *ecc++ = ((bch_val1 >> 8) & 0xFF);
+ *ecc++ = (bch_val1 & 0xFF);
+ /* 14th byte of ecc not used */
+ *ecc++ = 0;
+ } else {
+ /* BCH4 ecc scheme */
+ *ecc++ = ((bch_val2 >> 12) & 0xFF);
+ *ecc++ = ((bch_val2 >> 4) & 0xFF);
+ *ecc++ = (((bch_val2 & 0xF) << 4) |
+ ((bch_val1 >> 28) & 0xF));
+ *ecc++ = ((bch_val1 >> 20) & 0xFF);
+ *ecc++ = ((bch_val1 >> 12) & 0xFF);
+ *ecc++ = ((bch_val1 >> 4) & 0xFF);
+ *ecc++ = ((bch_val1 & 0xF) << 4);
+ }
+ }
+
+ gpmc_ecc_used = -EINVAL;
+ return 0;
+}
+EXPORT_SYMBOL_GPL(gpmc_calculate_ecc_bch);
+
+/**
* gpmc_calculate_ecc_bch4 - Generate 7 ecc bytes per sector of 512 data bytes
* @cs: chip select number
* @dat: The pointer to data on which ecc is computed
diff --git a/arch/arm/plat-omap/include/plat/gpmc.h b/arch/arm/plat-omap/include/plat/gpmc.h
index 2e6e259..c916510 100644
--- a/arch/arm/plat-omap/include/plat/gpmc.h
+++ b/arch/arm/plat-omap/include/plat/gpmc.h
@@ -185,6 +185,7 @@ int gpmc_enable_hwecc_bch(int cs, int mode, int dev_width, int nsectors,
int nerrors);
int gpmc_calculate_ecc_bch4(int cs, const u_char *dat, u_char *ecc);
int gpmc_calculate_ecc_bch8(int cs, const u_char *dat, u_char *ecc);
+int gpmc_calculate_ecc_bch(int cs, const u_char *dat, u_char *ecc);
#endif /* CONFIG_ARCH_OMAP3 */
#endif
--
1.7.0.4
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