[RSLIB] Support non-canonical GF representations
For the CAFÉ NAND controller, we need to support non-canonical representations of the Galois field. Allow the caller to provide its own function for generating the field, and CAFÉ can use rslib instead of its own implementation. Signed-off-by: Segher Boessenkool <segher@kernel.crashing.org> Signed-off-by: David Woodhouse <dwmw2@infradead.org>
This commit is contained in:
Segher Boessenkool
David Woodhouse
Родитель
7c96b7a146
Коммит
d7e5a5462f
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@ -34,6 +34,7 @@
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* @prim: Primitive element, index form
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* @iprim: prim-th root of 1, index form
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* @gfpoly: The primitive generator polynominal
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* @gffunc: Function to generate the field, if non-canonical representation
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* @users: Users of this structure
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* @list: List entry for the rs control list
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*/
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@ -48,6 +49,7 @@ struct rs_control {
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int prim;
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int iprim;
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int gfpoly;
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int (*gffunc)(int);
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int users;
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struct list_head list;
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};
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@ -77,6 +79,8 @@ int decode_rs16(struct rs_control *rs, uint16_t *data, uint16_t *par, int len,
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/* Create or get a matching rs control structure */
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struct rs_control *init_rs(int symsize, int gfpoly, int fcr, int prim,
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int nroots);
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struct rs_control *init_rs_non_canonical(int symsize, int (*func)(int),
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int fcr, int prim, int nroots);
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/* Release a rs control structure */
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void free_rs(struct rs_control *rs);
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@ -56,6 +56,7 @@ static DEFINE_MUTEX(rslistlock);
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* rs_init - Initialize a Reed-Solomon codec
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* @symsize: symbol size, bits (1-8)
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* @gfpoly: Field generator polynomial coefficients
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* @gffunc: Field generator function
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* @fcr: first root of RS code generator polynomial, index form
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* @prim: primitive element to generate polynomial roots
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* @nroots: RS code generator polynomial degree (number of roots)
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@ -63,8 +64,8 @@ static DEFINE_MUTEX(rslistlock);
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* Allocate a control structure and the polynom arrays for faster
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* en/decoding. Fill the arrays according to the given parameters.
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*/
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static struct rs_control *rs_init(int symsize, int gfpoly, int fcr,
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int prim, int nroots)
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static struct rs_control *rs_init(int symsize, int gfpoly, int (*gffunc)(int),
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int fcr, int prim, int nroots)
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{
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struct rs_control *rs;
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int i, j, sr, root, iprim;
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@ -82,6 +83,7 @@ static struct rs_control *rs_init(int symsize, int gfpoly, int fcr,
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rs->prim = prim;
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rs->nroots = nroots;
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rs->gfpoly = gfpoly;
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rs->gffunc = gffunc;
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/* Allocate the arrays */
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rs->alpha_to = kmalloc(sizeof(uint16_t) * (rs->nn + 1), GFP_KERNEL);
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@ -99,17 +101,26 @@ static struct rs_control *rs_init(int symsize, int gfpoly, int fcr,
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/* Generate Galois field lookup tables */
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rs->index_of[0] = rs->nn; /* log(zero) = -inf */
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rs->alpha_to[rs->nn] = 0; /* alpha**-inf = 0 */
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sr = 1;
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for (i = 0; i < rs->nn; i++) {
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rs->index_of[sr] = i;
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rs->alpha_to[i] = sr;
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sr <<= 1;
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if (sr & (1 << symsize))
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sr ^= gfpoly;
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sr &= rs->nn;
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if (gfpoly) {
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sr = 1;
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for (i = 0; i < rs->nn; i++) {
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rs->index_of[sr] = i;
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rs->alpha_to[i] = sr;
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sr <<= 1;
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if (sr & (1 << symsize))
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sr ^= gfpoly;
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sr &= rs->nn;
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}
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} else {
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sr = gffunc(0);
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for (i = 0; i < rs->nn; i++) {
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rs->index_of[sr] = i;
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rs->alpha_to[i] = sr;
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sr = gffunc(sr);
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}
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}
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/* If it's not primitive, exit */
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if(sr != 1)
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if(sr != rs->alpha_to[0])
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goto errpol;
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/* Find prim-th root of 1, used in decoding */
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@ -173,18 +184,22 @@ void free_rs(struct rs_control *rs)
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}
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/**
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* init_rs - Find a matching or allocate a new rs control structure
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* init_rs_internal - Find a matching or allocate a new rs control structure
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* @symsize: the symbol size (number of bits)
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* @gfpoly: the extended Galois field generator polynomial coefficients,
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* with the 0th coefficient in the low order bit. The polynomial
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* must be primitive;
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* @gffunc: pointer to function to generate the next field element,
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* or the multiplicative identity element if given 0. Used
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* instead of gfpoly if gfpoly is 0
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* @fcr: the first consecutive root of the rs code generator polynomial
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* in index form
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* @prim: primitive element to generate polynomial roots
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* @nroots: RS code generator polynomial degree (number of roots)
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*/
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struct rs_control *init_rs(int symsize, int gfpoly, int fcr, int prim,
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int nroots)
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static struct rs_control *init_rs_internal(int symsize, int gfpoly,
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int (*gffunc)(int), int fcr,
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int prim, int nroots)
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{
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struct list_head *tmp;
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struct rs_control *rs;
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@ -208,6 +223,8 @@ struct rs_control *init_rs(int symsize, int gfpoly, int fcr, int prim,
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continue;
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if (gfpoly != rs->gfpoly)
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continue;
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if (gffunc != rs->gffunc)
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continue;
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if (fcr != rs->fcr)
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continue;
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if (prim != rs->prim)
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@ -220,7 +237,7 @@ struct rs_control *init_rs(int symsize, int gfpoly, int fcr, int prim,
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}
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/* Create a new one */
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rs = rs_init(symsize, gfpoly, fcr, prim, nroots);
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rs = rs_init(symsize, gfpoly, gffunc, fcr, prim, nroots);
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if (rs) {
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rs->users = 1;
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list_add(&rs->list, &rslist);
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@ -230,6 +247,42 @@ out:
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return rs;
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}
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/**
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* init_rs - Find a matching or allocate a new rs control structure
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* @symsize: the symbol size (number of bits)
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* @gfpoly: the extended Galois field generator polynomial coefficients,
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* with the 0th coefficient in the low order bit. The polynomial
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* must be primitive;
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* @fcr: the first consecutive root of the rs code generator polynomial
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* in index form
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* @prim: primitive element to generate polynomial roots
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* @nroots: RS code generator polynomial degree (number of roots)
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*/
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struct rs_control *init_rs(int symsize, int gfpoly, int fcr, int prim,
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int nroots)
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{
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return init_rs_internal(symsize, gfpoly, NULL, fcr, prim, nroots);
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}
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/**
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* init_rs_non_canonical - Find a matching or allocate a new rs control
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* structure, for fields with non-canonical
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* representation
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* @symsize: the symbol size (number of bits)
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* @gffunc: pointer to function to generate the next field element,
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* or the multiplicative identity element if given 0. Used
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* instead of gfpoly if gfpoly is 0
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* @fcr: the first consecutive root of the rs code generator polynomial
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* in index form
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* @prim: primitive element to generate polynomial roots
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* @nroots: RS code generator polynomial degree (number of roots)
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*/
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struct rs_control *init_rs_non_canonical(int symsize, int (*gffunc)(int),
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int fcr, int prim, int nroots)
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{
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return init_rs_internal(symsize, 0, gffunc, fcr, prim, nroots);
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}
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#ifdef CONFIG_REED_SOLOMON_ENC8
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/**
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* encode_rs8 - Calculate the parity for data values (8bit data width)
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@ -321,6 +374,7 @@ EXPORT_SYMBOL_GPL(decode_rs16);
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#endif
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EXPORT_SYMBOL_GPL(init_rs);
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EXPORT_SYMBOL_GPL(init_rs_non_canonical);
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EXPORT_SYMBOL_GPL(free_rs);
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MODULE_LICENSE("GPL");
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