> -----Original Message----- > From: Vimal Singh [mailto:vimal.newwork@xxxxxxxxx] > Sent: Thursday, January 20, 2011 8:47 PM > To: Ghorai, Sukumar > Cc: linux-omap@xxxxxxxxxxxxxxx; linux-mtd@xxxxxxxxxxxxxxxxxxx; linux-arm- > kernel@xxxxxxxxxxxxxxxxxxx; Kamat, Nishant > Subject: Re: [PATCH] omap3: nand: bch ecc support added > > Hi Ghorai, > > I am the initial author of this patch. And I guess this patch still > uses most of my work. [Ghorai] I know you are working on it, But I think your code was in a shape for - 1. not for up-streamble shape 2. non functional, So can you check this version matching with your original code? In that case I can add your Signed-off. > > > Thanks and Regards, > Vimal > > On Thu, Jan 20, 2011 at 3:48 PM, Sukumar Ghorai <s-ghorai@xxxxxx> wrote: > > bch error correction (t=4 and t=8) for 512 bytes support added. > > Tested in omap-3630 es-1.1 silicon. > > > > Need to select the bch-ecc from board file. E.g. > > arch/arm/mach-omap2/board-flash.c: board_nand_init() > > board_nand_data.ecc_opt = OMAP_ECC_BCH4_CODE_HW > > > > This patch has dependency on - > > http://www.mail-archive.com/linux-omap@xxxxxxxxxxxxxxx/msg42658.html > > > > Signed-off-by: Sukumar Ghorai <s-ghorai@xxxxxx> > > --- > > arch/arm/mach-omap2/gpmc.c | 126 ++++++++--- > > arch/arm/plat-omap/include/plat/gpmc.h | 6 +- > > drivers/mtd/nand/Makefile | 1 + > > drivers/mtd/nand/omap2.c | 119 ++++++++-- > > drivers/mtd/nand/omap_bch_decoder.c | 393 > ++++++++++++++++++++++++++++++++ > > 5 files changed, 583 insertions(+), 62 deletions(-) > > create mode 100644 drivers/mtd/nand/omap_bch_decoder.c > > > > diff --git a/arch/arm/mach-omap2/gpmc.c b/arch/arm/mach-omap2/gpmc.c > > index 29c9732..91cfdca 100644 > > --- a/arch/arm/mach-omap2/gpmc.c > > +++ b/arch/arm/mach-omap2/gpmc.c > > @@ -48,6 +48,7 @@ > > #define GPMC_ECC_CONTROL 0x1f8 > > #define GPMC_ECC_SIZE_CONFIG 0x1fc > > #define GPMC_ECC1_RESULT 0x200 > > +#define GPMC_ECC_BCH_RESULT_0 0x240 > > > > #define GPMC_CS0_OFFSET 0x60 > > #define GPMC_CS_SIZE 0x30 > > @@ -94,7 +95,6 @@ static struct resource gpmc_mem_root; > > static struct resource gpmc_cs_mem[GPMC_CS_NUM]; > > static DEFINE_SPINLOCK(gpmc_mem_lock); > > static unsigned int gpmc_cs_map; /* flag for cs which are > initialized */ > > -static int gpmc_ecc_used = -EINVAL; /* cs using ecc engine */ > > > > static void __iomem *gpmc_base; > > > > @@ -832,52 +832,77 @@ void omap3_gpmc_restore_context(void) > > > > /** > > * gpmc_enable_hwecc - enable hardware ecc functionality > > + * @ecc_type: ecc type e.g. Hamming, BCH > > * @cs: chip select number > > * @mode: read/write mode > > * @dev_width: device bus width(1 for x16, 0 for x8) > > * @ecc_size: bytes for which ECC will be generated > > */ > > -int gpmc_enable_hwecc(int cs, int mode, int dev_width, int ecc_size) > > +int gpmc_enable_hwecc(int ecc_type, int cs, int mode, > > + int dev_width, int ecc_size) > > { > > - unsigned int val; > > - > > - /* check if ecc module is in used */ > > - if (gpmc_ecc_used != -EINVAL) > > - return -EINVAL; > > - > > - gpmc_ecc_used = cs; > > - > > - /* clear ecc and enable bits */ > > - val = ((0x00000001<<8) | 0x00000001); > > - gpmc_write_reg(GPMC_ECC_CONTROL, val); > > - > > - /* program ecc and result sizes */ > > - val = ((((ecc_size >> 1) - 1) << 22) | (0x0000000F)); > > - gpmc_write_reg(GPMC_ECC_SIZE_CONFIG, val); > > + unsigned int bch_mod = 0, bch_wrapmode = 0, eccsize1 = 0, > eccsize0 = 0; > > + unsigned int ecc_conf_val = 0, ecc_size_conf_val = 0; > > > > switch (mode) { > > case GPMC_ECC_READ: > > - gpmc_write_reg(GPMC_ECC_CONTROL, 0x101); > > + if (ecc_type == OMAP_ECC_BCH4_CODE_HW) { > > + eccsize1 = 0xD; eccsize0 = 0x48; > > + bch_mod = 0; > > + bch_wrapmode = 0x09; > > + } else if (ecc_type == OMAP_ECC_BCH8_CODE_HW) { > > + eccsize1 = 0x1A; eccsize0 = 0x18; > > + bch_mod = 1; > > + bch_wrapmode = 0x04; > > + } else > > + eccsize1 = ((ecc_size >> 1) - 1) << 22; > > break; > > + > > case GPMC_ECC_READSYN: > > - gpmc_write_reg(GPMC_ECC_CONTROL, 0x100); > > break; > > + > > case GPMC_ECC_WRITE: > > - gpmc_write_reg(GPMC_ECC_CONTROL, 0x101); > > + if (ecc_type == OMAP_ECC_BCH4_CODE_HW) { > > + eccsize1 = 0x20; eccsize0 = 0x00; > > + bch_mod = 0; > > + bch_wrapmode = 0x06; > > + } else if (ecc_type == OMAP_ECC_BCH8_CODE_HW) { > > + eccsize1 = 0x20; eccsize0 = 0x00; > > + bch_mod = 1; > > + bch_wrapmode = 0x06; > > + } else > > + eccsize1 = ((ecc_size >> 1) - 1) << 22; > > break; > > + > > default: > > printk(KERN_INFO "Error: Unrecognized Mode[%d]!\n", > mode); > > break; > > } > > > > - /* (ECC 16 or 8 bit col) | ( CS ) | ECC Enable */ > > - val = (dev_width << 7) | (cs << 1) | (0x1); > > - gpmc_write_reg(GPMC_ECC_CONFIG, val); > > + /* clear ecc and enable bits */ > > + if ((ecc_type == OMAP_ECC_BCH4_CODE_HW) || > > + (ecc_type == OMAP_ECC_BCH8_CODE_HW)) { > > + gpmc_write_reg(GPMC_ECC_CONTROL, 0x00000001); > > + ecc_size_conf_val = (eccsize1 << 22) | (eccsize0 << 12); > > + ecc_conf_val = ((0x01 << 16) | (bch_mod << 12) > > + | (bch_wrapmode << 8) | (dev_width << 7) > > + | (0x03 << 4) | (cs << 1) | (0x1)); > > + } else { > > + gpmc_write_reg(GPMC_ECC_CONTROL, 0x00000101); > > + ecc_size_conf_val = (eccsize1 << 22) | 0x0000000F; > > + ecc_conf_val = (dev_width << 7) | (cs << 1) | (0x1); > > + } > > + > > + gpmc_write_reg(GPMC_ECC_SIZE_CONFIG, ecc_size_conf_val); > > + gpmc_write_reg(GPMC_ECC_CONFIG, ecc_conf_val); > > + gpmc_write_reg(GPMC_ECC_CONTROL, 0x00000101); > > + > > return 0; > > } > > > > /** > > * gpmc_calculate_ecc - generate non-inverted ecc bytes > > + * @ecc_type: ecc type e.g. Hamming, BCH > > * @cs: chip select number > > * @dat: data pointer over which ecc is computed > > * @ecc_code: ecc code buffer > > @@ -888,20 +913,51 @@ int gpmc_enable_hwecc(int cs, int mode, int > dev_width, int ecc_size) > > * an erased page will produce an ECC mismatch between generated and > read > > * ECC bytes that has to be dealt with separately. > > */ > > -int gpmc_calculate_ecc(int cs, const u_char *dat, u_char *ecc_code) > > +int gpmc_calculate_ecc(int ecc_type, int cs, > > + const u_char *dat, u_char *ecc_code) > > { > > - unsigned int val = 0x0; > > - > > - if (gpmc_ecc_used != cs) > > - return -EINVAL; > > + unsigned int reg; > > + unsigned int val1 = 0x0, val2 = 0x0; > > + unsigned int val3 = 0x0, val4 = 0x0; > > + int i; > > > > - /* read ecc result */ > > - val = gpmc_read_reg(GPMC_ECC1_RESULT); > > - *ecc_code++ = val; /* P128e, ..., P1e */ > > - *ecc_code++ = val >> 16; /* P128o, ..., P1o */ > > - /* P2048o, P1024o, P512o, P256o, P2048e, P1024e, P512e, P256e */ > > - *ecc_code++ = ((val >> 8) & 0x0f) | ((val >> 20) & 0xf0); > > + if ((ecc_type == OMAP_ECC_BCH4_CODE_HW) || > > + (ecc_type == OMAP_ECC_BCH8_CODE_HW)) { > > + for (i = 0; i < 4; i++) { > > + /* > > + * Reading HW ECC_BCH_Results > > + * 0x240-0x24C, 0x250-0x25C, 0x260-0x26C, 0x270- > 0x27C > > + */ > > + reg = GPMC_ECC_BCH_RESULT_0 + (0x10 * i); > > + val1 = gpmc_read_reg(reg); > > + val2 = gpmc_read_reg(reg + 4); > > + if (ecc_type == OMAP_ECC_BCH8_CODE_HW) { > > + val3 = gpmc_read_reg(reg + 8); > > + val4 = gpmc_read_reg(reg + 12); > > + > > + *ecc_code++ = (val4 & 0xFF); > > + *ecc_code++ = ((val3 >> 24) & 0xFF); > > + *ecc_code++ = ((val3 >> 16) & 0xFF); > > + *ecc_code++ = ((val3 >> 8) & 0xFF); > > + *ecc_code++ = (val3 & 0xFF); > > + *ecc_code++ = ((val2 >> 24) & 0xFF); > > + } > > + *ecc_code++ = ((val2 >> 16) & 0xFF); > > + *ecc_code++ = ((val2 >> 8) & 0xFF); > > + *ecc_code++ = (val2 & 0xFF); > > + *ecc_code++ = ((val1 >> 24) & 0xFF); > > + *ecc_code++ = ((val1 >> 16) & 0xFF); > > + *ecc_code++ = ((val1 >> 8) & 0xFF); > > + *ecc_code++ = (val1 & 0xFF); > > + } > > + } else { > > + /* read ecc result */ > > + val1 = gpmc_read_reg(GPMC_ECC1_RESULT); > > + *ecc_code++ = val1; /* P128e, ..., P1e */ > > + *ecc_code++ = val1 >> 16; /* P128o, ..., P1o */ > > + /* P2048o, P1024o, P512o, P256o, P2048e, P1024e, P512e, > P256e */ > > + *ecc_code++ = ((val1 >> 8) & 0x0f) | ((val1 >> 20) & > 0xf0); > > + } > > > > - gpmc_ecc_used = -EINVAL; > > return 0; > > } > > diff --git a/arch/arm/plat-omap/include/plat/gpmc.h b/arch/arm/plat- > omap/include/plat/gpmc.h > > index 49aea09..838c185 100644 > > --- a/arch/arm/plat-omap/include/plat/gpmc.h > > +++ b/arch/arm/plat-omap/include/plat/gpmc.h > > @@ -92,6 +92,8 @@ enum omap_ecc { > > OMAP_ECC_HAMMING_CODE_HW, /* gpmc to detect the error */ > > /* 1-bit ecc: stored at begining of spare area as romcode > */ > > OMAP_ECC_HAMMING_CODE_HW_ROMCODE, /* gpmc method & romcode layout > */ > > + OMAP_ECC_BCH4_CODE_HW, /* gpmc bch detection & s/w method > correction */ > > + OMAP_ECC_BCH8_CODE_HW, /* gpmc bch detection & s/w method > correction */ > > }; > > > > /* > > @@ -156,6 +158,6 @@ extern int gpmc_cs_configure(int cs, int cmd, int > wval); > > extern int gpmc_nand_read(int cs, int cmd); > > extern int gpmc_nand_write(int cs, int cmd, int wval); > > > > -int gpmc_enable_hwecc(int cs, int mode, int dev_width, int ecc_size); > > -int gpmc_calculate_ecc(int cs, const u_char *dat, u_char *ecc_code); > > +int gpmc_enable_hwecc(int ecc, int cs, int mode, int dev_width, int > ecc_size); > > +int gpmc_calculate_ecc(int ecc, int cs, const u_char *dat, u_char > *ecc_code); > > #endif > > diff --git a/drivers/mtd/nand/Makefile b/drivers/mtd/nand/Makefile > > index 8ad6fae..ae02711 100644 > > --- a/drivers/mtd/nand/Makefile > > +++ b/drivers/mtd/nand/Makefile > > @@ -29,6 +29,7 @@ obj-$(CONFIG_MTD_NAND_NDFC) += ndfc.o > > obj-$(CONFIG_MTD_NAND_ATMEL) += atmel_nand.o > > obj-$(CONFIG_MTD_NAND_GPIO) += gpio.o > > obj-$(CONFIG_MTD_NAND_OMAP2) += omap2.o > > +obj-$(CONFIG_MTD_NAND_OMAP2) += omap_bch_decoder.o > > obj-$(CONFIG_MTD_NAND_CM_X270) += cmx270_nand.o > > obj-$(CONFIG_MTD_NAND_PXA3xx) += pxa3xx_nand.o > > obj-$(CONFIG_MTD_NAND_TMIO) += tmio_nand.o > > diff --git a/drivers/mtd/nand/omap2.c b/drivers/mtd/nand/omap2.c > > index 4e33972..14c7dfe 100644 > > --- a/drivers/mtd/nand/omap2.c > > +++ b/drivers/mtd/nand/omap2.c > > @@ -98,6 +98,8 @@ > > static const char *part_probes[] = { "cmdlinepart", NULL }; > > #endif > > > > +int decode_bch(int select_4_8, unsigned char *ecc, unsigned int > *err_loc); > > + > > /* oob info generated runtime depending on ecc algorithm and layout > selected */ > > static struct nand_ecclayout omap_oobinfo; > > /* Define some generic bad / good block scan pattern which are used > > @@ -130,7 +132,8 @@ struct omap_nand_info { > > OMAP_NAND_IO_WRITE, /* write */ > > } iomode; > > u_char *buf; > > - int buf_len; > > + int buf_len; > > + int ecc_opt; > > }; > > > > /** > > @@ -529,7 +532,6 @@ static void omap_read_buf_irq_pref(struct mtd_info > *mtd, u_char *buf, int len) > > struct omap_nand_info *info = container_of(mtd, > > struct omap_nand_info, > mtd); > > int ret = 0; > > - > > if (len <= mtd->oobsize) { > > omap_read_buf_pref(mtd, buf, len); > > return; > > @@ -803,6 +805,8 @@ static int omap_correct_data(struct mtd_info *mtd, > u_char *dat, > > struct omap_nand_info *info = container_of(mtd, struct > omap_nand_info, > > mtd); > > int blockCnt = 0, i = 0, ret = 0; > > + int j, eccsize, eccflag, count; > > + unsigned int err_loc[8]; > > > > /* Ex NAND_ECC_HW12_2048 */ > > if ((info->nand.ecc.mode == NAND_ECC_HW) && > > @@ -811,16 +815,57 @@ static int omap_correct_data(struct mtd_info *mtd, > u_char *dat, > > else > > blockCnt = 1; > > > > - for (i = 0; i < blockCnt; i++) { > > - if (memcmp(read_ecc, calc_ecc, 3) != 0) { > > - ret = omap_compare_ecc(read_ecc, calc_ecc, dat); > > - if (ret < 0) > > - return ret; > > + switch (info->ecc_opt) { > > + case OMAP_ECC_HAMMING_CODE_HW: > > + case OMAP_ECC_HAMMING_CODE_HW_ROMCODE: > > + for (i = 0; i < blockCnt; i++) { > > + if (memcmp(read_ecc, calc_ecc, 3) != 0) { > > + ret = omap_compare_ecc(read_ecc, > calc_ecc, dat); > > + if (ret < 0) > > + return ret; > > + } > > + read_ecc += 3; > > + calc_ecc += 3; > > + dat += 512; > > } > > - read_ecc += 3; > > - calc_ecc += 3; > > - dat += 512; > > + break; > > + > > + case OMAP_ECC_BCH4_CODE_HW: > > + eccsize = 7; > > + gpmc_calculate_ecc(info->ecc_opt, info->gpmc_cs, dat, > calc_ecc); > > + for (i = 0; i < blockCnt; i++) { > > + /* check if any ecc error */ > > + eccflag = 0; > > + for (j = 0; (j < eccsize) && (eccflag == 0); > j++) > > + if (calc_ecc[j] != 0) > > + eccflag = 1; > > + > > + if (eccflag == 1) { > > + eccflag = 0; > > + for (j = 0; (j < eccsize) && > > + (eccflag == 0); j++) > > + if (read_ecc[j] != 0xFF) > > + eccflag = 1; > > + } > > + > > + count = 0; > > + if (eccflag == 1) > > + count = decode_bch(0, calc_ecc, > err_loc); > > + > > + for (j = 0; j < count; j++) { > > + if (err_loc[j] < 4096) > > + dat[err_loc[j] >> 3] ^= > > + 1 << (err_loc[j] > & 7); > > + /* else, not interested to correct ecc > */ > > + } > > + > > + calc_ecc = calc_ecc + eccsize; > > + read_ecc = read_ecc + eccsize; > > + dat += 512; > > + } > > + break; > > } > > + > > return 0; > > } > > > > @@ -841,7 +886,7 @@ static int omap_calculate_ecc(struct mtd_info *mtd, > const u_char *dat, > > { > > struct omap_nand_info *info = container_of(mtd, struct > omap_nand_info, > > mtd); > > - return gpmc_calculate_ecc(info->gpmc_cs, dat, ecc_code); > > + return gpmc_calculate_ecc(info->ecc_opt, info->gpmc_cs, dat, > ecc_code); > > } > > > > /** > > @@ -856,7 +901,8 @@ static void omap_enable_hwecc(struct mtd_info *mtd, > int mode) > > struct nand_chip *chip = mtd->priv; > > unsigned int dev_width = (chip->options & NAND_BUSWIDTH_16) ? 1 : > 0; > > > > - gpmc_enable_hwecc(info->gpmc_cs, mode, dev_width, info- > >nand.ecc.size); > > + gpmc_enable_hwecc(info->ecc_opt, info->gpmc_cs, mode, > > + dev_width, info->nand.ecc.size); > > } > > > > /** > > @@ -953,6 +999,7 @@ static int __devinit omap_nand_probe(struct > platform_device *pdev) > > info->mtd.priv = &info->nand; > > info->mtd.name = dev_name(&pdev->dev); > > info->mtd.owner = THIS_MODULE; > > + info->ecc_opt = pdata->ecc_opt; > > > > info->nand.options = pdata->devsize; > > info->nand.options |= NAND_SKIP_BBTSCAN; > > @@ -991,7 +1038,6 @@ static int __devinit omap_nand_probe(struct > platform_device *pdev) > > info->nand.waitfunc = omap_wait; > > info->nand.chip_delay = 50; > > } > > - > > switch (pdata->xfer_type) { > > case NAND_OMAP_PREFETCH_POLLED: > > info->nand.read_buf = omap_read_buf_pref; > > @@ -1052,10 +1098,17 @@ static int __devinit omap_nand_probe(struct > platform_device *pdev) > > /* selsect the ecc type */ > > if (pdata->ecc_opt == OMAP_ECC_HAMMING_CODE_DEFAULT) > > info->nand.ecc.mode = NAND_ECC_SOFT; > > - else if ((pdata->ecc_opt == OMAP_ECC_HAMMING_CODE_HW) || > > - (pdata->ecc_opt == OMAP_ECC_HAMMING_CODE_HW_ROMCODE)) { > > - info->nand.ecc.bytes = 3; > > - info->nand.ecc.size = 512; > > + else { > > + if (pdata->ecc_opt == OMAP_ECC_BCH4_CODE_HW) { > > + info->nand.ecc.bytes = 4*7; > > + info->nand.ecc.size = 4*512; > > + } else if (pdata->ecc_opt == OMAP_ECC_BCH8_CODE_HW) { > > + info->nand.ecc.bytes = 13; > > + info->nand.ecc.size = 4*512; > > + } else { > > + info->nand.ecc.bytes = 3; > > + info->nand.ecc.size = 512; > > + } > > info->nand.ecc.calculate = omap_calculate_ecc; > > info->nand.ecc.hwctl = omap_enable_hwecc; > > info->nand.ecc.correct = omap_correct_data; > > @@ -1073,8 +1126,8 @@ static int __devinit omap_nand_probe(struct > platform_device *pdev) > > } > > } > > > > - /* rom code layout */ > > - if (pdata->ecc_opt == OMAP_ECC_HAMMING_CODE_HW_ROMCODE) { > > + /* select ecc lyout */ > > + if (info->nand.ecc.mode != NAND_ECC_SOFT) { > > > > if (info->nand.options & NAND_BUSWIDTH_16) > > offset = 2; > > @@ -1082,15 +1135,31 @@ static int __devinit omap_nand_probe(struct > platform_device *pdev) > > offset = 1; > > info->nand.badblock_pattern = > &bb_descrip_flashbased; > > } > > - omap_oobinfo.eccbytes = 3 * (info->mtd.oobsize/16); > > - for (i = 0; i < omap_oobinfo.eccbytes; i++) > > - omap_oobinfo.eccpos[i] = i+offset; > > > > - omap_oobinfo.oobfree->offset = offset + > omap_oobinfo.eccbytes; > > - omap_oobinfo.oobfree->length = info->mtd.oobsize - > > - (offset + > omap_oobinfo.eccbytes); > > + if (info->mtd.oobsize == 64) > > + omap_oobinfo.eccbytes = info->nand.ecc.bytes * > > + 2048/info- > >nand.ecc.size; > > + else > > + omap_oobinfo.eccbytes = info->nand.ecc.bytes; > > + > > + if (pdata->ecc_opt == OMAP_ECC_HAMMING_CODE_HW_ROMCODE) > { > > + for (i = 0; i < omap_oobinfo.eccbytes; i++) > > + omap_oobinfo.eccpos[i] = i + offset; > > + omap_oobinfo.oobfree->offset = > > + offset + > omap_oobinfo.eccbytes; > > + omap_oobinfo.oobfree->length = info->mtd.oobsize > - > > + offset - > omap_oobinfo.eccbytes; > > + } else { > > > > + omap_oobinfo.oobfree->offset = offset; > > + omap_oobinfo.oobfree->length = info->mtd.oobsize > - > > + offset - > omap_oobinfo.eccbytes; > > + offset = info->mtd.oobsize - > omap_oobinfo.eccbytes; > > + for (i = 0; i < omap_oobinfo.eccbytes; i++) > > + omap_oobinfo.eccpos[i] = i + offset; > > + } > > info->nand.ecc.layout = &omap_oobinfo; > > + > > } > > > > #ifdef CONFIG_MTD_PARTITIONS > > diff --git a/drivers/mtd/nand/omap_bch_decoder.c > b/drivers/mtd/nand/omap_bch_decoder.c > > new file mode 100644 > > index 0000000..da42bda > > --- /dev/null > > +++ b/drivers/mtd/nand/omap_bch_decoder.c > > @@ -0,0 +1,393 @@ > > +/* > > + * drivers/mtd/nand/omap_omap_bch_decoder.c > > + * > > + * Whole BCH ECC Decoder (Post hardware generated syndrome decoding) > > + * > > + * Copyright (c) 2007 Texas Instruments > > + * > > + * Author: Sukumar Ghorai <s-ghorai@xxxxxx > > + * Michael Fillinger <m-fillinger@xxxxxx> > > + * > > + * This program is free software; you can redistribute it and/or modify > > + * it under the terms of the GNU General Public License version 2 as > > + * published by the Free Software Foundation. > > + */ > > +#undef DEBUG > > + > > +#include <linux/kernel.h> > > +#include <linux/module.h> > > + > > +#define mm 13 > > +#define kk_shorten 4096 > > +#define nn 8191 /* Length of codeword, n = 2**mm - 1 */ > > + > > +#define PPP 0x201B /* Primary Polynomial : x^13 + x^4 + x^3 + x + 1 > */ > > +#define P 0x001B /* With omitted x^13 */ > > +#define POLY 12 /* degree of the primary Polynomial less one */ > > + > > +/** > > + * mpy_mod_gf - GALOIS field multiplier > > + * Input : A(x), B(x) > > + * Output : A(x)*B(x) mod P(x) > > + */ > > +static unsigned int mpy_mod_gf(unsigned int a, unsigned int b) > > +{ > > + unsigned int R = 0; > > + unsigned int R1 = 0; > > + unsigned int k = 0; > > + > > + for (k = 0; k < mm; k++) { > > + > > + R = (R << 1) & 0x1FFE; > > + if (R1 == 1) > > + R ^= P; > > + > > + if (((a >> (POLY - k)) & 1) == 1) > > + R ^= b; > > + > > + if (k < POLY) > > + R1 = (R >> POLY) & 1; > > + } > > + return R; > > +} > > + > > +/** > > + * chien - CHIEN search > > + * > > + * @location - Error location vector pointer > > + * > > + * Inputs : ELP(z) > > + * No. of found errors > > + * Size of input codeword > > + * Outputs : Up to 8 locations > > + * No. of errors > > + */ > > +static int chien(unsigned int select_4_8, int err_nums, > > + unsigned int err[], unsigned int > *location) > > +{ > > + int i, count; /* Number of dectected errors */ > > + /* Contains accumulation of evaluation at x^i (i:1->8) */ > > + unsigned int gammas[8] = {0}; > > + unsigned int alpha; > > + unsigned int bit, ecc_bits; > > + unsigned int elp_sum; > > + > > + ecc_bits = (select_4_8 == 0) ? 52 : 104; > > + > > + /* Start evaluation at Alpha**8192 and decreasing */ > > + for (i = 0; i < 8; i++) > > + gammas[i] = err[i]; > > + > > + count = 0; > > + for (i = 1; (i <= nn) && (count < err_nums); i++) { > > + > > + /* Result of evaluation at root */ > > + elp_sum = 1 ^ gammas[0] ^ gammas[1] ^ > > + gammas[2] ^ gammas[3] ^ > > + gammas[4] ^ gammas[5] ^ > > + gammas[6] ^ gammas[7]; > > + > > + alpha = PPP >> 1; > > + gammas[0] = mpy_mod_gf(gammas[0], alpha); > > + alpha = mpy_mod_gf(alpha, (PPP >> 1)); /* x alphha^-2 > */ > > + gammas[1] = mpy_mod_gf(gammas[1], alpha); > > + alpha = mpy_mod_gf(alpha, (PPP >> 1)); /* x alphha^-2 > */ > > + gammas[2] = mpy_mod_gf(gammas[2], alpha); > > + alpha = mpy_mod_gf(alpha, (PPP >> 1)); /* x alphha^-3 > */ > > + gammas[3] = mpy_mod_gf(gammas[3], alpha); > > + alpha = mpy_mod_gf(alpha, (PPP >> 1)); /* x alphha^-4 > */ > > + gammas[4] = mpy_mod_gf(gammas[4], alpha); > > + alpha = mpy_mod_gf(alpha, (PPP >> 1)); /* x alphha^-5 > */ > > + gammas[5] = mpy_mod_gf(gammas[5], alpha); > > + alpha = mpy_mod_gf(alpha, (PPP >> 1)); /* x alphha^-6 > */ > > + gammas[6] = mpy_mod_gf(gammas[6], alpha); > > + alpha = mpy_mod_gf(alpha, (PPP >> 1)); /* x alphha^-7 > */ > > + gammas[7] = mpy_mod_gf(gammas[7], alpha); > > + > > + if (elp_sum == 0) { > > + /* calculate bit position in main data area */ > > + bit = ((i-1) & ~7)|(7-((i-1) & 7)); > > + if (i >= 2 * ecc_bits) > > + location[count++] = > > + kk_shorten - (bit - 2 * > ecc_bits) - 1; > > + } > > + } > > + > > + /* Failure: No. of detected errors != No. or corrected errors */ > > + if (count != err_nums) { > > + count = -1; > > + printk(KERN_ERR "BCH decoding failed\n"); > > + } > > + for (i = 0; i < count; i++) > > + pr_debug("%d ", location[i]); > > + > > + return count; > > +} > > + > > +/* synd : 16 Syndromes > > + * return: gamaas - Coefficients to the error polynomial > > + * return: : Number of detected errors > > +*/ > > +static unsigned int berlekamp(unsigned int select_4_8, > > + unsigned int synd[], unsigned int err[]) > > +{ > > + int loop, iteration; > > + unsigned int LL = 0; /* Detected errors */ > > + unsigned int d = 0; /* Distance between Syndromes and > ELP[n](z) */ > > + unsigned int invd = 0; /* Inverse of d */ > > + /* Intermediate ELP[n](z). > > + * Final ELP[n](z) is Error Location Polynomial > > + */ > > + unsigned int gammas[16] = {0}; > > + /* Intermediate normalized ELP[n](z) : D[n](z) */ > > + unsigned int D[16] = {0}; > > + /* Temporary value that holds an ELP[n](z) coefficient */ > > + unsigned int next_gamma = 0; > > + > > + int e = 0; > > + unsigned int sign = 0; > > + unsigned int u = 0; > > + unsigned int v = 0; > > + unsigned int C1 = 0, C2 = 0; > > + unsigned int ss = 0; > > + unsigned int tmp_v = 0, tmp_s = 0; > > + unsigned int tmp_poly; > > + > > + /*-------------- Step 0 ------------------*/ > > + for (loop = 0; loop < 16; loop++) > > + gammas[loop] = 0; > > + gammas[0] = 1; > > + D[1] = 1; > > + > > + iteration = 0; > > + LL = 0; > > + while ((iteration < ((select_4_8+1)*2*4)) && > > + (LL <= ((select_4_8+1)*4))) { > > + > > + pr_debug("\nIteration.............%d\n", iteration); > > + d = 0; > > + /* Step: 0 */ > > + for (loop = 0; loop <= LL; loop++) { > > + tmp_poly = mpy_mod_gf( > > + gammas[loop], synd[iteration - > loop]); > > + d ^= tmp_poly; > > + pr_debug("%02d. s=0 LL=%x poly %x\n", > > + loop, LL, tmp_poly); > > + } > > + > > + /* Step 1: 1 cycle only to perform inversion */ > > + v = d << 1; > > + e = -1; > > + sign = 1; > > + ss = 0x2000; > > + invd = 0; > > + u = PPP; > > + for (loop = 0; (d != 0) && (loop <= (2 * POLY)); loop++) > { > > + pr_debug("%02d. s=1 LL=%x poly NULL\n", > > + loop, LL); > > + C1 = (v >> 13) & 1; > > + C2 = C1 & sign; > > + > > + sign ^= C2 ^ (e == 0); > > + > > + tmp_v = v; > > + tmp_s = ss; > > + > > + if (C1 == 1) { > > + v ^= u; > > + ss ^= invd; > > + } > > + v = (v << 1) & 0x3FFF; > > + if (C2 == 1) { > > + u = tmp_v; > > + invd = tmp_s; > > + e = -e; > > + } > > + invd >>= 1; > > + e--; > > + } > > + > > + for (loop = 0; (d != 0) && (loop <= (iteration + 1)); > loop++) { > > + /* Step 2 > > + * Interleaved with Step 3, if L<(n-k) > > + * invd: Update of ELP[n](z) = ELP[n-1](z) - > d.D[n-1](z) > > + */ > > + > > + /* Holds value of ELP coefficient until > precedent > > + * value does not have to be used anymore > > + */ > > + tmp_poly = mpy_mod_gf(d, D[loop]); > > + pr_debug("%02d. s=2 LL=%x poly %x\n", > > + loop, LL, tmp_poly); > > + > > + next_gamma = gammas[loop] ^ tmp_poly; > > + if ((2 * LL) < (iteration + 1)) { > > + /* Interleaving with Step 3 > > + * for parallelized update of ELP(z) and > D(z) > > + */ > > + } else { > > + /* Update of ELP(z) only -> stay in Step > 2 */ > > + gammas[loop] = next_gamma; > > + if (loop == (iteration + 1)) { > > + /* to step 4 */ > > + break; > > + } > > + } > > + > > + /* Step 3 > > + * Always interleaved with Step 2 (case when > L<(n-k)) > > + * Update of D[n-1](z) = ELP[n-1](z)/d > > + */ > > + D[loop] = mpy_mod_gf(gammas[loop], invd); > > + pr_debug("%02d. s=3 LL=%x poly %x\n", > > + loop, LL, D[loop]); > > + > > + /* Can safely update ELP[n](z) */ > > + gammas[loop] = next_gamma; > > + > > + if (loop == (iteration + 1)) { > > + /* If update finished */ > > + LL = iteration - LL + 1; > > + /* to step 4 */ > > + break; > > + } > > + /* Else, interleaving to step 2*/ > > + } > > + > > + /* Step 4: Update D(z): i:0->L */ > > + /* Final update of D[n](z) = D[n](z).z*/ > > + for (loop = 0; loop < 15; loop++) /* Left Shift */ > > + D[15 - loop] = D[14 - loop]; > > + > > + D[0] = 0; > > + > > + iteration++; > > + } /* while */ > > + > > + /* Processing finished, copy ELP to final registers : 0->2t-1*/ > > + for (loop = 0; loop < 8; loop++) > > + err[loop] = gammas[loop+1]; > > + > > + pr_debug("\n Err poly:"); > > + for (loop = 0; loop < 8; loop++) > > + pr_debug("0x%x ", err[loop]); > > + > > + return LL; > > +} > > + > > +/* > > + * syndrome - Generate syndrome components from hw generate syndrome > > + * r(x) = c(x) + e(x) > > + * s(x) = c(x) mod g(x) + e(x) mod g(x) = e(x) mod g(x) > > + * so receiver checks if the syndrome s(x) = r(x) mod g(x) is equal to > zero. > > + * unsigned int s[16]; - Syndromes > > + */ > > +static void syndrome(unsigned int select_4_8, > > + unsigned char *ecc, unsigned int > syn[]) > > +{ > > + unsigned int k, l, t; > > + unsigned int alpha_bit, R_bit; > > + int ecc_pos, ecc_min; > > + > > + /* 2t-1 = 15 (for t=8) minimal polynomials of the first 15 > powers of a > > + * primitive elemmants of GF(m); Even powers minimal polynomials > are > > + * duplicate of odd powers' minimal polynomials. > > + * Odd powers of alpha (1 to 15) > > + */ > > + unsigned int pow_alpha[8] = {0x0002, 0x0008, 0x0020, 0x0080, > > + 0x0200, 0x0800, 0x001B, 0x006C}; > > + > > + pr_debug("\n ECC[0..n]: "); > > + for (k = 0; k < 13; k++) > > + pr_debug("0x%x ", ecc[k]); > > + > > + if (select_4_8 == 0) { > > + t = 4; > > + ecc_pos = 55; /* bits(52-bits): 55->4 */ > > + ecc_min = 4; > > + } else { > > + t = 8; > > + ecc_pos = 103; /* bits: 103->0 */ > > + ecc_min = 0; > > + } > > + > > + /* total numbber of syndrom to be used is 2t */ > > + /* Step1: calculate the odd syndrome(s) */ > > + R_bit = ((ecc[ecc_pos/8] >> (7 - ecc_pos%8)) & 1); > > + ecc_pos--; > > + for (k = 0; k < t; k++) > > + syn[2 * k] = R_bit; > > + > > + while (ecc_pos >= ecc_min) { > > + R_bit = ((ecc[ecc_pos/8] >> (7 - ecc_pos%8)) & 1); > > + ecc_pos--; > > + > > + for (k = 0; k < t; k++) { > > + /* Accumulate value of x^i at alpha^(2k+1) */ > > + if (R_bit == 1) > > + syn[2*k] ^= pow_alpha[k]; > > + > > + /* Compute a**(2k+1), using LSFR */ > > + for (l = 0; l < (2 * k + 1); l++) { > > + alpha_bit = (pow_alpha[k] >> POLY) & 1; > > + pow_alpha[k] = (pow_alpha[k] << 1) & > 0x1FFF; > > + if (alpha_bit == 1) > > + pow_alpha[k] ^= P; > > + } > > + } > > + } > > + > > + /* Step2: calculate the even syndrome(s) > > + * Compute S(a), where a is an even power of alpha > > + * Evenry even power of primitive element has the same minimal > > + * polynomial as some odd power of elemets. > > + * And based on S(a^2) = S^2(a) > > + */ > > + for (k = 0; k < t; k++) > > + syn[2*k+1] = mpy_mod_gf(syn[k], syn[k]); > > + > > + pr_debug("\n Syndromes: "); > > + for (k = 0; k < 16; k++) > > + pr_debug("0x%x ", syn[k]); > > +} > > + > > +/** > > + * decode_bch - BCH decoder for 4- and 8-bit error correction > > + * > > + * @ecc - ECC syndrome generated by hw BCH engine > > + * @err_loc - pointer to error location array > > + * > > + * This function does post sydrome generation (hw generated) decoding > > + * for:- > > + * Dimension of Galoise Field: m = 13 > > + * Length of codeword: n = 2**m - 1 > > + * Number of errors that can be corrected: 4- or 8-bits > > + * Length of information bit: kk = nn - rr > > + */ > > +int decode_bch(int select_4_8, unsigned char *ecc, unsigned int > *err_loc) > > +{ > > + int no_of_err; > > + unsigned int syn[16] = {0,}; /* 16 Syndromes */ > > + unsigned int err_poly[8] = {0,}; > > + /* Coefficients to the error polynomial > > + * ELP(x) = 1 + err0.x + err1.x^2 + ... + err7.x^8 > > + */ > > + > > + /* Decoting involes three steps > > + * 1. Compute the syndrom from teh received codeword, > > + * 2. Find the error location polynomial from a set of equations > > + * derived from the syndrome, > > + * 3. Use the error location polynomial to identify errants bits, > > + * > > + * And correcttion done by bit flips using error locaiton and > expected > > + * to be outseide of this implementation. > > + */ > > + syndrome(select_4_8, ecc, syn); > > + no_of_err = berlekamp(select_4_8, syn, err_poly); > > + if (no_of_err <= (4 << select_4_8)) > > + no_of_err = chien(select_4_8, no_of_err, err_poly, > err_loc); > > + > > + return no_of_err; > > +} > > +EXPORT_SYMBOL(decode_bch); > > + > > -- > > 1.7.0.4 > > > > -- > > To unsubscribe from this list: send the line "unsubscribe linux-omap" in > > the body of a message to majordomo@xxxxxxxxxxxxxxx > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > > > > > -- > Regards, > Vimal Singh -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
