nfp: bpf: encode LMEM accesses

NFP LMEM is a large, indirectly accessed register file.  There
are two basic indirect access registers.  Each access operation
may either use offset (up to 8 or 16 words) or perform post
decrement/increment.

Add encodings of LMEM indexes as instruction operands.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Simon Horman <simon.horman@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/netronome/nfp/nfp_asm.c

@@ -48,6 +48,7 @@ const struct cmd_tgt_act cmd_tgt_act[__CMD_TGT_MAP_SIZE] = {
 
 static u16 nfp_swreg_to_unreg(swreg reg, bool is_dst)
 {
+	bool lm_id, lm_dec = false;
 	u16 val = swreg_value(reg);
 
 	switch (swreg_type(reg)) {
@@ -59,6 +60,33 @@ static u16 nfp_swreg_to_unreg(swreg reg, bool is_dst)
 		return UR_REG_NN | val;
 	case NN_REG_XFER:
 		return UR_REG_XFR | val;
+	case NN_REG_LMEM:
+		lm_id = swreg_lm_idx(reg);
+
+		switch (swreg_lm_mode(reg)) {
+		case NN_LM_MOD_NONE:
+			if (val & ~UR_REG_LM_IDX_MAX) {
+				pr_err("LM offset too large\n");
+				return 0;
+			}
+			return UR_REG_LM | FIELD_PREP(UR_REG_LM_IDX, lm_id) |
+				val;
+		case NN_LM_MOD_DEC:
+			lm_dec = true;
+			/* fall through */
+		case NN_LM_MOD_INC:
+			if (val) {
+				pr_err("LM offset in inc/dev mode\n");
+				return 0;
+			}
+			return UR_REG_LM | UR_REG_LM_POST_MOD |
+				FIELD_PREP(UR_REG_LM_IDX, lm_id) |
+				FIELD_PREP(UR_REG_LM_POST_MOD_DEC, lm_dec);
+		default:
+			pr_err("bad LM mode for unrestricted operands %d\n",
+			       swreg_lm_mode(reg));
+			return 0;
+		}
 	case NN_REG_IMM:
 		if (val & ~0xff) {
 			pr_err("immediate too large\n");
@@ -108,6 +136,7 @@ int swreg_to_unrestricted(swreg dst, swreg lreg, swreg rreg,
 static u16 nfp_swreg_to_rereg(swreg reg, bool is_dst, bool has_imm8, bool *i8)
 {
 	u16 val = swreg_value(reg);
+	bool lm_id;
 
 	switch (swreg_type(reg)) {
 	case NN_REG_GPR_A:
@@ -116,6 +145,21 @@ static u16 nfp_swreg_to_rereg(swreg reg, bool is_dst, bool has_imm8, bool *i8)
 		return val;
 	case NN_REG_XFER:
 		return RE_REG_XFR | val;
+	case NN_REG_LMEM:
+		lm_id = swreg_lm_idx(reg);
+
+		if (swreg_lm_mode(reg) != NN_LM_MOD_NONE) {
+			pr_err("bad LM mode for restricted operands %d\n",
+			       swreg_lm_mode(reg));
+			return 0;
+		}
+
+		if (val & ~RE_REG_LM_IDX_MAX) {
+			pr_err("LM offset too large\n");
+			return 0;
+		}
+
+		return RE_REG_LM | FIELD_PREP(RE_REG_LM_IDX, lm_id) | val;
 	case NN_REG_IMM:
 		if (val & ~(0x7f | has_imm8 << 7)) {
 			pr_err("immediate too large\n");

drivers/net/ethernet/netronome/nfp/nfp_asm.h

@@ -44,9 +44,17 @@
 #define RE_REG_IMM_encode(x)					\
 	(RE_REG_IMM | ((x) & 0x1f) | (((x) & 0x60) << 1))
 #define RE_REG_IMM_MAX	 0x07fULL
+#define RE_REG_LM	0x050
+#define RE_REG_LM_IDX	0x008
+#define RE_REG_LM_IDX_MAX	0x7
 #define RE_REG_XFR	0x080
 
 #define UR_REG_XFR	0x180
+#define UR_REG_LM	0x200
+#define UR_REG_LM_IDX	0x020
+#define UR_REG_LM_POST_MOD	0x010
+#define UR_REG_LM_POST_MOD_DEC	0x001
+#define UR_REG_LM_IDX_MAX	0xf
 #define UR_REG_NN	0x280
 #define UR_REG_NO_DST	0x300
 #define UR_REG_IMM	UR_REG_NO_DST
@@ -235,6 +243,8 @@ enum lcsr_wr_src {
 
 /* Software register representation, independent of operand type */
 #define NN_REG_TYPE	GENMASK(31, 24)
+#define NN_REG_LM_IDX	BIT(22)
+#define NN_REG_LM_MOD	GENMASK(21, 20)
 #define NN_REG_VAL	GENMASK(7, 0)
 
 enum nfp_bpf_reg_type {
@@ -245,6 +255,13 @@ enum nfp_bpf_reg_type {
 	NN_REG_XFER =	BIT(3),
 	NN_REG_IMM =	BIT(4),
 	NN_REG_NONE =	BIT(5),
+	NN_REG_LMEM =	BIT(6),
+};
+
+enum nfp_bpf_lm_mode {
+	NN_LM_MOD_NONE = 0,
+	NN_LM_MOD_INC,
+	NN_LM_MOD_DEC,
 };
 
 #define reg_both(x)	__enc_swreg((x), NN_REG_GPR_BOTH)
@@ -254,6 +271,10 @@ enum nfp_bpf_reg_type {
 #define reg_xfer(x)	__enc_swreg((x), NN_REG_XFER)
 #define reg_imm(x)	__enc_swreg((x), NN_REG_IMM)
 #define reg_none()	__enc_swreg(0, NN_REG_NONE)
+#define reg_lm(x, off)	__enc_swreg_lm((x), NN_LM_MOD_NONE, (off))
+#define reg_lm_inc(x)	__enc_swreg_lm((x), NN_LM_MOD_INC, 0)
+#define reg_lm_dec(x)	__enc_swreg_lm((x), NN_LM_MOD_DEC, 0)
+#define __reg_lm(x, mod, off)	__enc_swreg_lm((x), (mod), (off))
 
 typedef __u32 __bitwise swreg;
 
@@ -262,6 +283,16 @@ static inline swreg __enc_swreg(u16 id, u8 type)
 	return (__force swreg)(id | FIELD_PREP(NN_REG_TYPE, type));
 }
 
+static inline swreg __enc_swreg_lm(u8 id, enum nfp_bpf_lm_mode mode, u8 off)
+{
+	WARN_ON(id > 1 || (off && mode != NN_LM_MOD_NONE));
+
+	return (__force swreg)(FIELD_PREP(NN_REG_TYPE, NN_REG_LMEM) |
+			       FIELD_PREP(NN_REG_LM_IDX, id) |
+			       FIELD_PREP(NN_REG_LM_MOD, mode) |
+			       off);
+}
+
 static inline u32 swreg_raw(swreg reg)
 {
 	return (__force u32)reg;
@@ -277,6 +308,16 @@ static inline u16 swreg_value(swreg reg)
 	return FIELD_GET(NN_REG_VAL, swreg_raw(reg));
 }
 
+static inline bool swreg_lm_idx(swreg reg)
+{
+	return FIELD_GET(NN_REG_LM_IDX, swreg_raw(reg));
+}
+
+static inline enum nfp_bpf_lm_mode swreg_lm_mode(swreg reg)
+{
+	return FIELD_GET(NN_REG_LM_MOD, swreg_raw(reg));
+}
+
 struct nfp_insn_ur_regs {
 	enum alu_dst_ab dst_ab;
 	u16 dst;