lib: sbi: simplify pmp_set(), pmp_get()

pmpcfg_csr and pmpcfg_shift are only negative for an unexpected value of
__riscv_xlen. We can immediately return in this case.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Reviewed-by: Dong Du <Dd_nirvana@sjtu.edu.cn>
Reviewed-by: Anup Patel <anup.patel@wdc.com>

Author: xypron

lib/sbi/riscv_asm.c

@@ -261,12 +261,9 @@ int pmp_set(unsigned int n, unsigned long prot, unsigned long addr,
 	pmpcfg_csr   = (CSR_PMPCFG0 + (n >> 2)) & ~1;
 	pmpcfg_shift = (n & 7) << 3;
 #else
-	pmpcfg_csr   = -1;
-	pmpcfg_shift = -1;
+	return SBI_ENOTSUPP;
 #endif
 	pmpaddr_csr = CSR_PMPADDR0 + n;
-	if (pmpcfg_csr < 0 || pmpcfg_shift < 0)
-		return SBI_ENOTSUPP;
 
 	/* encode PMP config */
 	prot &= ~PMP_A;
@@ -315,12 +312,9 @@ int pmp_get(unsigned int n, unsigned long *prot_out, unsigned long *addr_out,
 	pmpcfg_csr   = (CSR_PMPCFG0 + (n >> 2)) & ~1;
 	pmpcfg_shift = (n & 7) << 3;
 #else
-	pmpcfg_csr   = -1;
-	pmpcfg_shift = -1;
+	return SBI_ENOTSUPP;
 #endif
 	pmpaddr_csr = CSR_PMPADDR0 + n;
-	if (pmpcfg_csr < 0 || pmpcfg_shift < 0)
-		return SBI_ENOTSUPP;
 
 	/* decode PMP config */
 	cfgmask = (0xffUL << pmpcfg_shift);