qed: Revisit chain implementation

RoCE driver is going to need a 32-bit chain [current chain implementation
for qed* currently supports only 16-bit producer/consumer chains].

This patch adds said support, as well as doing other slight tweaks and
modifications to qed's chain API.

Signed-off-by: Yuval Mintz <Yuval.Mintz@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 336 insertions, 220 deletions

diff --git a/include/linux/qed/qed_chain.h b/include/linux/qed/qed_chain.h
index 5f8fcaaa6504..eceaa9ed2ae9 100644
--- a/include/linux/qed/qed_chain.h
+++ b/include/linux/qed/qed_chain.h
@@ -47,16 +47,56 @@ enum qed_chain_use_mode {
         QED_CHAIN_USE_TO_CONSUME_PRODUCE,       /* Chain starts empty */
 };
 
+enum qed_chain_cnt_type {
+        /* The chain's size/prod/cons are kept in 16-bit variables */
+        QED_CHAIN_CNT_TYPE_U16,
+
+        /* The chain's size/prod/cons are kept in 32-bit variables  */
+        QED_CHAIN_CNT_TYPE_U32,
+};
+
 struct qed_chain_next {
         struct regpair  next_phys;
         void            *next_virt;
 };
 
+struct qed_chain_pbl_u16 {
+        u16 prod_page_idx;
+        u16 cons_page_idx;
+};
+
+struct qed_chain_pbl_u32 {
+        u32 prod_page_idx;
+        u32 cons_page_idx;
+};
+
 struct qed_chain_pbl {
+        /* Base address of a pre-allocated buffer for pbl */
         dma_addr_t      p_phys_table;
         void            *p_virt_table;
-        u16             prod_page_idx;
-        u16             cons_page_idx;
+
+        /* Table for keeping the virtual addresses of the chain pages,
+         * respectively to the physical addresses in the pbl table.
+         */
+        void **pp_virt_addr_tbl;
+
+        /* Index to current used page by producer/consumer */
+        union {
+                struct qed_chain_pbl_u16 pbl16;
+                struct qed_chain_pbl_u32 pbl32;
+        } u;
+};
+
+struct qed_chain_u16 {
+        /* Cyclic index of next element to produce/consme */
+        u16 prod_idx;
+        u16 cons_idx;
+};
+
+struct qed_chain_u32 {
+        /* Cyclic index of next element to produce/consme */
+        u32 prod_idx;
+        u32 cons_idx;
 };
 
 struct qed_chain {
@@ -64,13 +104,25 @@ struct qed_chain {
         dma_addr_t              p_phys_addr;
         void                    *p_prod_elem;
         void                    *p_cons_elem;
-        u16                     page_cnt;
+
         enum qed_chain_mode     mode;
         enum qed_chain_use_mode intended_use; /* used to produce/consume */
-        u16                     capacity; /*< number of _usable_ elements */
-        u16                     size; /* number of elements */
-        u16                     prod_idx;
-        u16                     cons_idx;
+        enum qed_chain_cnt_type cnt_type;
+
+        union {
+                struct qed_chain_u16 chain16;
+                struct qed_chain_u32 chain32;
+        } u;
+
+        u32 page_cnt;
+
+        /* Number of elements - capacity is for usable elements only,
+         * while size will contain total number of elements [for entire chain].
+         */
+        u32 capacity;
+        u32 size;
+
+        /* Elements information for fast calculations */
         u16                     elem_per_page;
         u16                     elem_per_page_mask;
         u16                     elem_unusable;
@@ -96,66 +148,69 @@ struct qed_chain {
 #define QED_CHAIN_PAGE_CNT(elem_cnt, elem_size, mode) \
         DIV_ROUND_UP(elem_cnt, USABLE_ELEMS_PER_PAGE(elem_size, mode))
 
+#define is_chain_u16(p) ((p)->cnt_type == QED_CHAIN_CNT_TYPE_U16)
+#define is_chain_u32(p) ((p)->cnt_type == QED_CHAIN_CNT_TYPE_U32)
+
 /* Accessors */
 static inline u16 qed_chain_get_prod_idx(struct qed_chain *p_chain)
 {
-        return p_chain->prod_idx;
+        return p_chain->u.chain16.prod_idx;
 }
 
 static inline u16 qed_chain_get_cons_idx(struct qed_chain *p_chain)
 {
-        return p_chain->cons_idx;
+        return p_chain->u.chain16.cons_idx;
+}
+
+static inline u32 qed_chain_get_cons_idx_u32(struct qed_chain *p_chain)
+{
+        return p_chain->u.chain32.cons_idx;
 }
 
 static inline u16 qed_chain_get_elem_left(struct qed_chain *p_chain)
 {
         u16 used;
 
-        /* we don't need to trancate upon assignmet, as we assign u32->u16 */
-        used = ((u32)0x10000u + (u32)(p_chain->prod_idx)) -
-                (u32)p_chain->cons_idx;
+        used = (u16) (((u32)0x10000 +
+                       (u32)p_chain->u.chain16.prod_idx) -
+                      (u32)p_chain->u.chain16.cons_idx);
         if (p_chain->mode == QED_CHAIN_MODE_NEXT_PTR)
-                used -= p_chain->prod_idx / p_chain->elem_per_page -
-                        p_chain->cons_idx / p_chain->elem_per_page;
+                used -= p_chain->u.chain16.prod_idx / p_chain->elem_per_page -
+                    p_chain->u.chain16.cons_idx / p_chain->elem_per_page;
 
-        return p_chain->capacity - used;
+        return (u16)(p_chain->capacity - used);
 }
 
-static inline u8 qed_chain_is_full(struct qed_chain *p_chain)
+static inline u32 qed_chain_get_elem_left_u32(struct qed_chain *p_chain)
 {
-        return qed_chain_get_elem_left(p_chain) == p_chain->capacity;
-}
+        u32 used;
 
-static inline u8 qed_chain_is_empty(struct qed_chain *p_chain)
-{
-        return qed_chain_get_elem_left(p_chain) == 0;
-}
+        used = (u32) (((u64)0x100000000ULL +
+                       (u64)p_chain->u.chain32.prod_idx) -
+                      (u64)p_chain->u.chain32.cons_idx);
+        if (p_chain->mode == QED_CHAIN_MODE_NEXT_PTR)
+                used -= p_chain->u.chain32.prod_idx / p_chain->elem_per_page -
+                    p_chain->u.chain32.cons_idx / p_chain->elem_per_page;
 
-static inline u16 qed_chain_get_elem_per_page(
-        struct qed_chain *p_chain)
-{
-        return p_chain->elem_per_page;
+        return p_chain->capacity - used;
 }
 
-static inline u16 qed_chain_get_usable_per_page(
-        struct qed_chain *p_chain)
+static inline u16 qed_chain_get_usable_per_page(struct qed_chain *p_chain)
 {
         return p_chain->usable_per_page;
 }
 
-static inline u16 qed_chain_get_unusable_per_page(
-        struct qed_chain *p_chain)
+static inline u16 qed_chain_get_unusable_per_page(struct qed_chain *p_chain)
 {
         return p_chain->elem_unusable;
 }
 
-static inline u16 qed_chain_get_size(struct qed_chain *p_chain)
+static inline u32 qed_chain_get_page_cnt(struct qed_chain *p_chain)
 {
-        return p_chain->size;
+        return p_chain->page_cnt;
 }
 
-static inline dma_addr_t
-qed_chain_get_pbl_phys(struct qed_chain *p_chain)
+static inline dma_addr_t qed_chain_get_pbl_phys(struct qed_chain *p_chain)
 {
         return p_chain->pbl.p_phys_table;
 }
@@ -172,65 +227,63 @@ qed_chain_get_pbl_phys(struct qed_chain *p_chain)
  */
 static inline void
 qed_chain_advance_page(struct qed_chain *p_chain,
-                       void **p_next_elem,
-                       u16 *idx_to_inc,
-                       u16 *page_to_inc)
+                       void **p_next_elem, void *idx_to_inc, void *page_to_inc)
 
 {
+        struct qed_chain_next *p_next = NULL;
+        u32 page_index = 0;
         switch (p_chain->mode) {
         case QED_CHAIN_MODE_NEXT_PTR:
-        {
-                struct qed_chain_next *p_next = *p_next_elem;
+                p_next = *p_next_elem;
                 *p_next_elem = p_next->next_virt;
-                *idx_to_inc += p_chain->elem_unusable;
+                if (is_chain_u16(p_chain))
+                        *(u16 *)idx_to_inc += p_chain->elem_unusable;
+                else
+                        *(u32 *)idx_to_inc += p_chain->elem_unusable;
                 break;
-        }
         case QED_CHAIN_MODE_SINGLE:
                 *p_next_elem = p_chain->p_virt_addr;
                 break;
 
         case QED_CHAIN_MODE_PBL:
-                /* It is assumed pages are sequential, next element needs
-                 * to change only when passing going back to first from last.
-                 */
-                if (++(*page_to_inc) == p_chain->page_cnt) {
-                        *page_to_inc = 0;
-                        *p_next_elem = p_chain->p_virt_addr;
+                if (is_chain_u16(p_chain)) {
+                        if (++(*(u16 *)page_to_inc) == p_chain->page_cnt)
+                                *(u16 *)page_to_inc = 0;
+                        page_index = *(u16 *)page_to_inc;
+                } else {
+                        if (++(*(u32 *)page_to_inc) == p_chain->page_cnt)
+                                *(u32 *)page_to_inc = 0;
+                        page_index = *(u32 *)page_to_inc;
                 }
+                *p_next_elem = p_chain->pbl.pp_virt_addr_tbl[page_index];
         }
 }
 
 #define is_unusable_idx(p, idx) \
-        (((p)->idx & (p)->elem_per_page_mask) == (p)->usable_per_page)
+        (((p)->u.chain16.idx & (p)->elem_per_page_mask) == (p)->usable_per_page)
+
+#define is_unusable_idx_u32(p, idx) \
+        (((p)->u.chain32.idx & (p)->elem_per_page_mask) == (p)->usable_per_page)
+#define is_unusable_next_idx(p, idx)                             \
+        ((((p)->u.chain16.idx + 1) & (p)->elem_per_page_mask) == \
+         (p)->usable_per_page)
 
-#define is_unusable_next_idx(p, idx) \
-        ((((p)->idx + 1) & (p)->elem_per_page_mask) == (p)->usable_per_page)
+#define is_unusable_next_idx_u32(p, idx)                         \
+        ((((p)->u.chain32.idx + 1) & (p)->elem_per_page_mask) == \
+         (p)->usable_per_page)
 
-#define test_ans_skip(p, idx)                           \
+#define test_and_skip(p, idx)                                              \
         do {                                            \
-                if (is_unusable_idx(p, idx)) {          \
-                        (p)->idx += (p)->elem_unusable; \
+                if (is_chain_u16(p)) {                                     \
+                        if (is_unusable_idx(p, idx))                       \
+                                (p)->u.chain16.idx += (p)->elem_unusable;  \
+                } else {                                                   \
+                        if (is_unusable_idx_u32(p, idx))                   \
+                                (p)->u.chain32.idx += (p)->elem_unusable;  \
                 }                                       \
         } while (0)
 
 /**
- * @brief qed_chain_return_multi_produced -
- *
- * A chain in which the driver "Produces" elements should use this API
- * to indicate previous produced elements are now consumed.
- *
- * @param p_chain
- * @param num
- */
-static inline void
-qed_chain_return_multi_produced(struct qed_chain *p_chain,
-                                u16 num)
-{
-        p_chain->cons_idx += num;
-        test_ans_skip(p_chain, cons_idx);
-}
-
-/**
  * @brief qed_chain_return_produced -
  *
  * A chain in which the driver "Produces" elements should use this API
@@ -240,8 +293,11 @@ qed_chain_return_multi_produced(struct qed_chain *p_chain,
  */
 static inline void qed_chain_return_produced(struct qed_chain *p_chain)
 {
-        p_chain->cons_idx++;
-        test_ans_skip(p_chain, cons_idx);
+        if (is_chain_u16(p_chain))
+                p_chain->u.chain16.cons_idx++;
+        else
+                p_chain->u.chain32.cons_idx++;
+        test_and_skip(p_chain, cons_idx);
 }
 
 /**
@@ -257,21 +313,33 @@ static inline void qed_chain_return_produced(struct qed_chain *p_chain)
  */
 static inline void *qed_chain_produce(struct qed_chain *p_chain)
 {
-        void *ret = NULL;
-
-        if ((p_chain->prod_idx & p_chain->elem_per_page_mask) ==
-            p_chain->next_page_mask) {
-                qed_chain_advance_page(p_chain, &p_chain->p_prod_elem,
-                                       &p_chain->prod_idx,
-                                       &p_chain->pbl.prod_page_idx);
+        void *p_ret = NULL, *p_prod_idx, *p_prod_page_idx;
+
+        if (is_chain_u16(p_chain)) {
+                if ((p_chain->u.chain16.prod_idx &
+                     p_chain->elem_per_page_mask) == p_chain->next_page_mask) {
+                        p_prod_idx = &p_chain->u.chain16.prod_idx;
+                        p_prod_page_idx = &p_chain->pbl.u.pbl16.prod_page_idx;
+                        qed_chain_advance_page(p_chain, &p_chain->p_prod_elem,
+                                               p_prod_idx, p_prod_page_idx);
+                }
+                p_chain->u.chain16.prod_idx++;
+        } else {
+                if ((p_chain->u.chain32.prod_idx &
+                     p_chain->elem_per_page_mask) == p_chain->next_page_mask) {
+                        p_prod_idx = &p_chain->u.chain32.prod_idx;
+                        p_prod_page_idx = &p_chain->pbl.u.pbl32.prod_page_idx;
+                        qed_chain_advance_page(p_chain, &p_chain->p_prod_elem,
+                                               p_prod_idx, p_prod_page_idx);
+                }
+                p_chain->u.chain32.prod_idx++;
         }
 
-        ret = p_chain->p_prod_elem;
-        p_chain->prod_idx++;
+        p_ret = p_chain->p_prod_elem;
         p_chain->p_prod_elem = (void *)(((u8 *)p_chain->p_prod_elem) +
                                         p_chain->elem_size);
 
-        return ret;
+        return p_ret;
 }
 
 /**
@@ -282,9 +350,9 @@ static inline void *qed_chain_produce(struct qed_chain *p_chain)
  * @param p_chain
  * @param num
  *
- * @return u16, number of unusable BDs
+ * @return number of unusable BDs
  */
-static inline u16 qed_chain_get_capacity(struct qed_chain *p_chain)
+static inline u32 qed_chain_get_capacity(struct qed_chain *p_chain)
 {
         return p_chain->capacity;
 }
@@ -297,11 +365,13 @@ static inline u16 qed_chain_get_capacity(struct qed_chain *p_chain)
  *
  * @param p_chain
  */
-static inline void
-qed_chain_recycle_consumed(struct qed_chain *p_chain)
+static inline void qed_chain_recycle_consumed(struct qed_chain *p_chain)
 {
-        test_ans_skip(p_chain, prod_idx);
-        p_chain->prod_idx++;
+        test_and_skip(p_chain, prod_idx);
+        if (is_chain_u16(p_chain))
+                p_chain->u.chain16.prod_idx++;
+        else
+                p_chain->u.chain32.prod_idx++;
 }
 
 /**
@@ -316,21 +386,33 @@ qed_chain_recycle_consumed(struct qed_chain *p_chain)
  */
 static inline void *qed_chain_consume(struct qed_chain *p_chain)
 {
-        void *ret = NULL;
-
-        if ((p_chain->cons_idx & p_chain->elem_per_page_mask) ==
-            p_chain->next_page_mask) {
+        void *p_ret = NULL, *p_cons_idx, *p_cons_page_idx;
+
+        if (is_chain_u16(p_chain)) {
+                if ((p_chain->u.chain16.cons_idx &
+                     p_chain->elem_per_page_mask) == p_chain->next_page_mask) {
+                        p_cons_idx = &p_chain->u.chain16.cons_idx;
+                        p_cons_page_idx = &p_chain->pbl.u.pbl16.cons_page_idx;
+                        qed_chain_advance_page(p_chain, &p_chain->p_cons_elem,
+                                               p_cons_idx, p_cons_page_idx);
+                }
+                p_chain->u.chain16.cons_idx++;
+        } else {
+                if ((p_chain->u.chain32.cons_idx &
+                     p_chain->elem_per_page_mask) == p_chain->next_page_mask) {
+                        p_cons_idx = &p_chain->u.chain32.cons_idx;
+                        p_cons_page_idx = &p_chain->pbl.u.pbl32.cons_page_idx;
                 qed_chain_advance_page(p_chain, &p_chain->p_cons_elem,
-                                       &p_chain->cons_idx,
-                                       &p_chain->pbl.cons_page_idx);
+                                               p_cons_idx, p_cons_page_idx);
+                }
+                p_chain->u.chain32.cons_idx++;
         }
 
-        ret = p_chain->p_cons_elem;
-        p_chain->cons_idx++;
+        p_ret = p_chain->p_cons_elem;
         p_chain->p_cons_elem = (void *)(((u8 *)p_chain->p_cons_elem) +
                                         p_chain->elem_size);
 
-        return ret;
+        return p_ret;
 }
 
 /**
@@ -340,16 +422,33 @@ static inline void *qed_chain_consume(struct qed_chain *p_chain)
  */
 static inline void qed_chain_reset(struct qed_chain *p_chain)
 {
-        int i;
-
-        p_chain->prod_idx       = 0;
-        p_chain->cons_idx       = 0;
-        p_chain->p_cons_elem    = p_chain->p_virt_addr;
-        p_chain->p_prod_elem    = p_chain->p_virt_addr;
+        u32 i;
+
+        if (is_chain_u16(p_chain)) {
+                p_chain->u.chain16.prod_idx = 0;
+                p_chain->u.chain16.cons_idx = 0;
+        } else {
+                p_chain->u.chain32.prod_idx = 0;
+                p_chain->u.chain32.cons_idx = 0;
+        }
+        p_chain->p_cons_elem = p_chain->p_virt_addr;
+        p_chain->p_prod_elem = p_chain->p_virt_addr;
 
         if (p_chain->mode == QED_CHAIN_MODE_PBL) {
-                p_chain->pbl.prod_page_idx      = p_chain->page_cnt - 1;
-                p_chain->pbl.cons_page_idx      = p_chain->page_cnt - 1;
+                /* Use (page_cnt - 1) as a reset value for the prod/cons page's
+                 * indices, to avoid unnecessary page advancing on the first
+                 * call to qed_chain_produce/consume. Instead, the indices
+                 * will be advanced to page_cnt and then will be wrapped to 0.
+                 */
+                u32 reset_val = p_chain->page_cnt - 1;
+
+                if (is_chain_u16(p_chain)) {
+                        p_chain->pbl.u.pbl16.prod_page_idx = (u16)reset_val;
+                        p_chain->pbl.u.pbl16.cons_page_idx = (u16)reset_val;
+                } else {
+                        p_chain->pbl.u.pbl32.prod_page_idx = reset_val;
+                        p_chain->pbl.u.pbl32.cons_page_idx = reset_val;
+                }
         }
 
         switch (p_chain->intended_use) {
@@ -377,168 +476,184 @@ static inline void qed_chain_reset(struct qed_chain *p_chain)
  * @param intended_use
  * @param mode
  */
-static inline void qed_chain_init(struct qed_chain *p_chain,
-                                  void *p_virt_addr,
-                                  dma_addr_t p_phys_addr,
-                                  u16 page_cnt,
-                                  u8 elem_size,
-                                  enum qed_chain_use_mode intended_use,
-                                  enum qed_chain_mode mode)
+static inline void qed_chain_init_params(struct qed_chain *p_chain,
+                                         u32 page_cnt,
+                                         u8 elem_size,
+                                         enum qed_chain_use_mode intended_use,
+                                         enum qed_chain_mode mode,
+                                         enum qed_chain_cnt_type cnt_type)
 {
         /* chain fixed parameters */
-        p_chain->p_virt_addr    = p_virt_addr;
-        p_chain->p_phys_addr    = p_phys_addr;
+        p_chain->p_virt_addr = NULL;
+        p_chain->p_phys_addr = 0;
         p_chain->elem_size      = elem_size;
-        p_chain->page_cnt       = page_cnt;
+        p_chain->intended_use = intended_use;
         p_chain->mode           = mode;
+        p_chain->cnt_type = cnt_type;
 
-        p_chain->intended_use           = intended_use;
         p_chain->elem_per_page          = ELEMS_PER_PAGE(elem_size);
-        p_chain->usable_per_page =
-                USABLE_ELEMS_PER_PAGE(elem_size, mode);
-        p_chain->capacity               = p_chain->usable_per_page * page_cnt;
-        p_chain->size                   = p_chain->elem_per_page * page_cnt;
+        p_chain->usable_per_page = USABLE_ELEMS_PER_PAGE(elem_size, mode);
         p_chain->elem_per_page_mask     = p_chain->elem_per_page - 1;
-
         p_chain->elem_unusable = UNUSABLE_ELEMS_PER_PAGE(elem_size, mode);
-
         p_chain->next_page_mask = (p_chain->usable_per_page &
                                    p_chain->elem_per_page_mask);
 
-        if (mode == QED_CHAIN_MODE_NEXT_PTR) {
-                struct qed_chain_next   *p_next;
-                u16                     i;
-
-                for (i = 0; i < page_cnt - 1; i++) {
-                        /* Increment mem_phy to the next page. */
-                        p_phys_addr += QED_CHAIN_PAGE_SIZE;
-
-                        /* Initialize the physical address of the next page. */
-                        p_next = (struct qed_chain_next *)((u8 *)p_virt_addr +
-                                                           elem_size *
-                                                           p_chain->
-                                                           usable_per_page);
-
-                        p_next->next_phys.lo    = DMA_LO_LE(p_phys_addr);
-                        p_next->next_phys.hi    = DMA_HI_LE(p_phys_addr);
-
-                        /* Initialize the virtual address of the next page. */
-                        p_next->next_virt = (void *)((u8 *)p_virt_addr +
-                                                     QED_CHAIN_PAGE_SIZE);
-
-                        /* Move to the next page. */
-                        p_virt_addr = p_next->next_virt;
-                }
-
-                /* Last page's next should point to beginning of the chain */
-                p_next = (struct qed_chain_next *)((u8 *)p_virt_addr +
-                                                   elem_size *
-                                                   p_chain->usable_per_page);
+        p_chain->page_cnt = page_cnt;
+        p_chain->capacity = p_chain->usable_per_page * page_cnt;
+        p_chain->size = p_chain->elem_per_page * page_cnt;
 
-                p_next->next_phys.lo    = DMA_LO_LE(p_chain->p_phys_addr);
-                p_next->next_phys.hi    = DMA_HI_LE(p_chain->p_phys_addr);
-                p_next->next_virt       = p_chain->p_virt_addr;
-        }
-        qed_chain_reset(p_chain);
+        p_chain->pbl.p_phys_table = 0;
+        p_chain->pbl.p_virt_table = NULL;
+        p_chain->pbl.pp_virt_addr_tbl = NULL;
 }
 
 /**
- * @brief qed_chain_pbl_init - Initalizes a basic pbl chain
- *        struct
+ * @brief qed_chain_init_mem -
+ *
+ * Initalizes a basic chain struct with its chain buffers
+ *
  * @param p_chain
  * @param p_virt_addr   virtual address of allocated buffer's beginning
  * @param p_phys_addr   physical address of allocated buffer's beginning
- * @param page_cnt      number of pages in the allocated buffer
- * @param elem_size     size of each element in the chain
- * @param use_mode
- * @param p_phys_pbl    pointer to a pre-allocated side table
- *                      which will hold physical page addresses.
- * @param p_virt_pbl    pointer to a pre allocated side table
- *                      which will hold virtual page addresses.
+ *
  */
-static inline void
-qed_chain_pbl_init(struct qed_chain *p_chain,
-                   void *p_virt_addr,
-                   dma_addr_t p_phys_addr,
-                   u16 page_cnt,
-                   u8 elem_size,
-                   enum qed_chain_use_mode use_mode,
-                   dma_addr_t p_phys_pbl,
-                   dma_addr_t *p_virt_pbl)
+static inline void qed_chain_init_mem(struct qed_chain *p_chain,
+                                      void *p_virt_addr, dma_addr_t p_phys_addr)
 {
-        dma_addr_t *p_pbl_dma = p_virt_pbl;
-        int i;
-
-        qed_chain_init(p_chain, p_virt_addr, p_phys_addr, page_cnt,
-                       elem_size, use_mode, QED_CHAIN_MODE_PBL);
+        p_chain->p_virt_addr = p_virt_addr;
+        p_chain->p_phys_addr = p_phys_addr;
+}
 
+/**
+ * @brief qed_chain_init_pbl_mem -
+ *
+ * Initalizes a basic chain struct with its pbl buffers
+ *
+ * @param p_chain
+ * @param p_virt_pbl    pointer to a pre allocated side table which will hold
+ *                      virtual page addresses.
+ * @param p_phys_pbl    pointer to a pre-allocated side table which will hold
+ *                      physical page addresses.
+ * @param pp_virt_addr_tbl
+ *                      pointer to a pre-allocated side table which will hold
+ *                      the virtual addresses of the chain pages.
+ *
+ */
+static inline void qed_chain_init_pbl_mem(struct qed_chain *p_chain,
+                                          void *p_virt_pbl,
+                                          dma_addr_t p_phys_pbl,
+                                          void **pp_virt_addr_tbl)
+{
         p_chain->pbl.p_phys_table = p_phys_pbl;
         p_chain->pbl.p_virt_table = p_virt_pbl;
-
-        /* Fill the PBL with physical addresses*/
-        for (i = 0; i < page_cnt; i++) {
-                *p_pbl_dma = p_phys_addr;
-                p_phys_addr += QED_CHAIN_PAGE_SIZE;
-                p_pbl_dma++;
-        }
+        p_chain->pbl.pp_virt_addr_tbl = pp_virt_addr_tbl;
 }
 
 /**
- * @brief qed_chain_set_prod - sets the prod to the given
- *        value
+ * @brief qed_chain_init_next_ptr_elem -
+ *
+ * Initalizes a next pointer element
+ *
+ * @param p_chain
+ * @param p_virt_curr   virtual address of a chain page of which the next
+ *                      pointer element is initialized
+ * @param p_virt_next   virtual address of the next chain page
+ * @param p_phys_next   physical address of the next chain page
  *
- * @param prod_idx
- * @param p_prod_elem
  */
-static inline void qed_chain_set_prod(struct qed_chain *p_chain,
-                                      u16 prod_idx,
-                                      void *p_prod_elem)
+static inline void
+qed_chain_init_next_ptr_elem(struct qed_chain *p_chain,
+                             void *p_virt_curr,
+                             void *p_virt_next, dma_addr_t p_phys_next)
 {
-        p_chain->prod_idx       = prod_idx;
-        p_chain->p_prod_elem    = p_prod_elem;
+        struct qed_chain_next *p_next;
+        u32 size;
+
+        size = p_chain->elem_size * p_chain->usable_per_page;
+        p_next = (struct qed_chain_next *)((u8 *)p_virt_curr + size);
+
+        DMA_REGPAIR_LE(p_next->next_phys, p_phys_next);
+
+        p_next->next_virt = p_virt_next;
 }
 
 /**
- * @brief qed_chain_get_elem -
+ * @brief qed_chain_get_last_elem -
  *
- * get a pointer to an element represented by absolute idx
+ * Returns a pointer to the last element of the chain
  *
  * @param p_chain
- * @assumption p_chain->size is a power of 2
  *
- * @return void*, a pointer to next element
+ * @return void*
  */
-static inline void *qed_chain_sge_get_elem(struct qed_chain *p_chain,
-                                           u16 idx)
+static inline void *qed_chain_get_last_elem(struct qed_chain *p_chain)
 {
-        void *ret = NULL;
-
-        if (idx >= p_chain->size)
-                return NULL;
+        struct qed_chain_next *p_next = NULL;
+        void *p_virt_addr = NULL;
+        u32 size, last_page_idx;
 
-        ret = (u8 *)p_chain->p_virt_addr + p_chain->elem_size * idx;
+        if (!p_chain->p_virt_addr)
+                goto out;
 
-        return ret;
+        switch (p_chain->mode) {
+        case QED_CHAIN_MODE_NEXT_PTR:
+                size = p_chain->elem_size * p_chain->usable_per_page;
+                p_virt_addr = p_chain->p_virt_addr;
+                p_next = (struct qed_chain_next *)((u8 *)p_virt_addr + size);
+                while (p_next->next_virt != p_chain->p_virt_addr) {
+                        p_virt_addr = p_next->next_virt;
+                        p_next = (struct qed_chain_next *)((u8 *)p_virt_addr +
+                                                           size);
+                }
+                break;
+        case QED_CHAIN_MODE_SINGLE:
+                p_virt_addr = p_chain->p_virt_addr;
+                break;
+        case QED_CHAIN_MODE_PBL:
+                last_page_idx = p_chain->page_cnt - 1;
+                p_virt_addr = p_chain->pbl.pp_virt_addr_tbl[last_page_idx];
+                break;
+        }
+        /* p_virt_addr points at this stage to the last page of the chain */
+        size = p_chain->elem_size * (p_chain->usable_per_page - 1);
+        p_virt_addr = (u8 *)p_virt_addr + size;
+out:
+        return p_virt_addr;
 }
 
 /**
- * @brief qed_chain_sge_inc_cons_prod
+ * @brief qed_chain_set_prod - sets the prod to the given value
  *
- * for sge chains, producer isn't increased serially, the ring
- * is expected to be full at all times. Once elements are
- * consumed, they are immediately produced.
+ * @param prod_idx
+ * @param p_prod_elem
+ */
+static inline void qed_chain_set_prod(struct qed_chain *p_chain,
+                                      u32 prod_idx, void *p_prod_elem)
+{
+        if (is_chain_u16(p_chain))
+                p_chain->u.chain16.prod_idx = (u16) prod_idx;
+        else
+                p_chain->u.chain32.prod_idx = prod_idx;
+        p_chain->p_prod_elem = p_prod_elem;
+}
+
+/**
+ * @brief qed_chain_pbl_zero_mem - set chain memory to 0
  *
  * @param p_chain
- * @param cnt
- *
- * @return inline void
  */
-static inline void
-qed_chain_sge_inc_cons_prod(struct qed_chain *p_chain,
-                            u16 cnt)
+static inline void qed_chain_pbl_zero_mem(struct qed_chain *p_chain)
 {
-        p_chain->prod_idx += cnt;
-        p_chain->cons_idx += cnt;
+        u32 i, page_cnt;
+
+        if (p_chain->mode != QED_CHAIN_MODE_PBL)
+                return;
+
+        page_cnt = qed_chain_get_page_cnt(p_chain);
+
+        for (i = 0; i < page_cnt; i++)
+                memset(p_chain->pbl.pp_virt_addr_tbl[i], 0,
+                       QED_CHAIN_PAGE_SIZE);
 }
 
 #endif
diff --git a/include/linux/qed/qed_if.h b/include/linux/qed/qed_if.h
index 4c29439f54bf..15efccfdc46e 100644
--- a/include/linux/qed/qed_if.h
+++ b/include/linux/qed/qed_if.h
@@ -325,7 +325,8 @@ struct qed_common_ops {
         int             (*chain_alloc)(struct qed_dev *cdev,
                                        enum qed_chain_use_mode intended_use,
                                        enum qed_chain_mode mode,
-                                       u16 num_elems,
+                                       enum qed_chain_cnt_type cnt_type,
+                                       u32 num_elems,
                                        size_t elem_size,
                                        struct qed_chain *p_chain);