[PATCH v2] mtd: atmel_nand: make PMECC lookup table and offset property optional
Josh Wu
josh.wu at atmel.com
Thu Sep 18 01:08:03 PDT 2014
Hi, Brain
On 9/18/2014 8:32 AM, Brian Norris wrote:
> On Mon, Aug 18, 2014 at 03:08:40PM +0800, Josh Wu wrote:
>> If there is no PMECC lookup table stored in ROM, or lookup table offset is
>> not specified, PMECC driver should build it in DDR by itself.
>>
>> That make the PMECC driver work for some board which doesn't has PMECC
>> lookup table in ROM.
>>
>> Signed-off-by: Josh Wu <josh.wu at atmel.com>
>> Cc: devicetree at vger.kernel.org
>> ---
>> This patch is based on mtd-l2/next branch
>>
>> v1 -> v2:
>> make create_lookup_table() static.
> sparse gives me several new complaints:
>
> +drivers/mtd/nand/atmel_nand.c:1219:50: warning: incorrect type in argument 2 (different signedness) [sparse]
> +drivers/mtd/nand/atmel_nand.c:1219:50: expected signed short [usertype] *index_of [sparse]
> +drivers/mtd/nand/atmel_nand.c:1219:50: got unsigned short [usertype] *addr [sparse]
> +drivers/mtd/nand/atmel_nand.c:1219:61: warning: incorrect type in argument 3 (different signedness) [sparse]
> +drivers/mtd/nand/atmel_nand.c:1219:61: expected signed short [usertype] *alpha_to [sparse]
> +drivers/mtd/nand/atmel_nand.c:1219:61: got unsigned short [usertype] * [sparse]
> +drivers/mtd/nand/atmel_nand.c:1292:38: warning: incorrect type in assignment (different address spaces) [sparse]
> +drivers/mtd/nand/atmel_nand.c:1292:38: expected void [noderef] <asn:2>*pmecc_rom_base [sparse]
> +drivers/mtd/nand/atmel_nand.c:1292:38: got unsigned short [usertype] *[assigned] galois_table [sparse]
>
> The third one might be a false positive. I suppose it's safe to use
> regular memory with __iomem accessors (but not vice versa).
Thanks. I will check this.
>
>> .../devicetree/bindings/mtd/atmel-nand.txt | 6 +-
>> drivers/mtd/nand/atmel_nand.c | 136 ++++++++++++++++++++-
>> 2 files changed, 136 insertions(+), 6 deletions(-)
>>
>> diff --git a/Documentation/devicetree/bindings/mtd/atmel-nand.txt b/Documentation/devicetree/bindings/mtd/atmel-nand.txt
>> index c472883..75d1847 100644
>> --- a/Documentation/devicetree/bindings/mtd/atmel-nand.txt
>> +++ b/Documentation/devicetree/bindings/mtd/atmel-nand.txt
>> @@ -5,7 +5,9 @@ Required properties:
>> - reg : should specify localbus address and size used for the chip,
>> and hardware ECC controller if available.
>> If the hardware ECC is PMECC, it should contain address and size for
>> - PMECC, PMECC Error Location controller and ROM which has lookup tables.
>> + PMECC and PMECC Error Location controller.
>> + The PMECC lookup table address and size in ROM is optional. If not
>> + specified, driver will build it in runtime.
>> - atmel,nand-addr-offset : offset for the address latch.
>> - atmel,nand-cmd-offset : offset for the command latch.
>> - #address-cells, #size-cells : Must be present if the device has sub-nodes
>> @@ -27,7 +29,7 @@ Optional properties:
>> are: 512, 1024.
>> - atmel,pmecc-lookup-table-offset : includes two offsets of lookup table in ROM
>> for different sector size. First one is for sector size 512, the next is for
>> - sector size 1024.
>> + sector size 1024. If not specified, driver will build the table in runtime.
>> - nand-bus-width : 8 or 16 bus width if not present 8
>> - nand-on-flash-bbt: boolean to enable on flash bbt option if not present false
>> - Nand Flash Controller(NFC) is a slave driver under Atmel nand flash
>> diff --git a/drivers/mtd/nand/atmel_nand.c b/drivers/mtd/nand/atmel_nand.c
>> index effa7a29..84af313 100644
>> --- a/drivers/mtd/nand/atmel_nand.c
>> +++ b/drivers/mtd/nand/atmel_nand.c
>> @@ -124,6 +124,7 @@ struct atmel_nand_host {
>> bool has_pmecc;
>> u8 pmecc_corr_cap;
>> u16 pmecc_sector_size;
>> + bool has_no_lookup_table;
>> u32 pmecc_lookup_table_offset;
>> u32 pmecc_lookup_table_offset_512;
>> u32 pmecc_lookup_table_offset_1024;
>> @@ -1109,12 +1110,121 @@ static int pmecc_choose_ecc(struct atmel_nand_host *host,
>> return 0;
>> }
>>
>> +static int pmecc_build_galois_table(int mm,
>> + int16_t *index_of, int16_t *alpha_to)
>> +{
>> + unsigned int i, mask, nn;
>> + unsigned int p[PMECC_GF_DIMENSION_14 + 1];
>> +
>> + nn = (1 << mm) - 1;
>> + /* set default value */
>> + for (i = 1; i < mm; i++)
>> + p[i] = 0;
>> +
>> + /* 1 + X^mm */
>> + p[0] = 1;
>> + p[mm] = 1;
>> +
>> + /* others */
>> + switch (mm) {
>> + case 3:
>> + case 4:
>> + case 6:
>> + case 15:
>> + p[1] = 1;
>> + break;
>> + case 5:
>> + case 11:
>> + p[2] = 1;
>> + break;
>> + case 7:
>> + case 10:
>> + p[3] = 1;
>> + break;
>> + case 8:
>> + p[2] = p[3] = p[4] = 1;
>> + break;
>> + case 9:
>> + p[4] = 1;
>> + break;
>> + case 12:
>> + p[1] = p[4] = p[6] = 1;
>> + break;
>> + case 13:
>> + p[1] = p[3] = p[4] = 1;
>> + break;
>> + case 14:
>> + p[1] = p[6] = p[10] = 1;
>> + break;
>> + default:
>> + /* Error */
>> + return -EINVAL;
>> + }
>> +
>> + /* Build alpha ^ mm it will help to generate the field (primitiv) */
>> + alpha_to[mm] = 0;
>> + for (i = 0; i < mm; i++)
>> + if (p[i])
>> + alpha_to[mm] |= 1 << i;
>> +
>> + /*
>> + * Then build elements from 0 to mm - 1. As degree is less than mm
>> + * so it is just a logical shift.
>> + */
>> + mask = 1;
>> + for (i = 0; i < mm; i++) {
>> + alpha_to[i] = mask;
>> + index_of[alpha_to[i]] = i;
>> + mask <<= 1;
>> + }
>> +
>> + index_of[alpha_to[mm]] = mm;
>> +
>> + /* use a mask to select the MSB bit of the LFSR */
>> + mask >>= 1;
>> +
>> + /* then finish the building */
>> + for (i = mm + 1; i <= nn; i++) {
>> + /* check if the msb bit of the lfsr is set */
>> + if (alpha_to[i - 1] & mask)
>> + alpha_to[i] = alpha_to[mm] ^
>> + ((alpha_to[i - 1] ^ mask) << 1);
>> + else
>> + alpha_to[i] = alpha_to[i - 1] << 1;
>> +
>> + index_of[alpha_to[i]] = i % nn;
>> + }
>> +
>> + /* index of 0 is undefined in a multiplicative field */
>> + index_of[0] = -1;
>> +
>> + return 0;
>> +}
> Is this algorithm documented? How did you come up with this?
It is not documented in datasheet. It is based BCH algorithm. But do you
know if the soft BCH use a same table like this?
Best Regards,
Josh Wu
>
>> +
>> +static uint16_t *create_lookup_table(struct device *dev, int sector_size)
>> +{
>> + int table_size = (sector_size == 512) ?
>> + PMECC_LOOKUP_TABLE_SIZE_512 :
>> + PMECC_LOOKUP_TABLE_SIZE_1024;
>> + int degree = (sector_size == 512) ?
>> + PMECC_GF_DIMENSION_13 :
>> + PMECC_GF_DIMENSION_14;
>> + uint16_t *addr = devm_kzalloc(dev, 2 * table_size * sizeof(uint16_t),
>> + GFP_KERNEL);
>> +
>> + if (addr)
>> + pmecc_build_galois_table(degree, addr, addr + table_size);
>> +
>> + return addr;
>> +}
>> +
>> static int atmel_pmecc_nand_init_params(struct platform_device *pdev,
>> struct atmel_nand_host *host)
>> {
>> struct mtd_info *mtd = &host->mtd;
>> struct nand_chip *nand_chip = &host->nand_chip;
>> struct resource *regs, *regs_pmerr, *regs_rom;
>> + uint16_t *galois_table;
>> int cap, sector_size, err_no;
>>
>> err_no = pmecc_choose_ecc(host, &cap, §or_size);
>> @@ -1160,8 +1270,24 @@ static int atmel_pmecc_nand_init_params(struct platform_device *pdev,
>> regs_rom = platform_get_resource(pdev, IORESOURCE_MEM, 3);
>> host->pmecc_rom_base = devm_ioremap_resource(&pdev->dev, regs_rom);
>> if (IS_ERR(host->pmecc_rom_base)) {
>> - err_no = PTR_ERR(host->pmecc_rom_base);
>> - goto err;
>> + if (!host->has_no_lookup_table)
>> + /* Don't display the information again */
>> + dev_err(host->dev, "Can not get I/O resource for ROM, will build a lookup table in runtime!\n");
>> +
>> + host->has_no_lookup_table = true;
>> + }
>> +
>> + if (host->has_no_lookup_table) {
>> + /* Build the look-up table in runtime */
>> + galois_table = create_lookup_table(host->dev, sector_size);
>> + if (!galois_table) {
>> + dev_err(host->dev, "Failed to build a lookup table in runtime!\n");
>> + err_no = -ENOMEM;
>> + goto err;
>> + }
>> +
>> + host->pmecc_rom_base = galois_table;
>> + host->pmecc_lookup_table_offset = 0;
>> }
>>
>> nand_chip->ecc.size = sector_size;
>> @@ -1498,8 +1624,10 @@ static int atmel_of_init_port(struct atmel_nand_host *host,
>>
>> if (of_property_read_u32_array(np, "atmel,pmecc-lookup-table-offset",
>> offset, 2) != 0) {
>> - dev_err(host->dev, "Cannot get PMECC lookup table offset\n");
>> - return -EINVAL;
>> + dev_err(host->dev, "Cannot get PMECC lookup table offset, will build a lookup table in runtime.\n");
>> + host->has_no_lookup_table = true;
>> + /* Will build a lookup table and initialize the offset later */
>> + return 0;
>> }
>> if (!offset[0] && !offset[1]) {
>> dev_err(host->dev, "Invalid PMECC lookup table offset\n");
> Brian
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