hwinfo: hwinfo_litex: Make compatible with both 8 and 32-bit CSRs

LiteX CSRs can only be accessed on addresses aligned to 4 bytes.
That's why in 32-bit CSRs case there is bit shifting needed.

Signed-off-by: Michal Sieron <[email protected]>

Author: michalsieron

drivers/hwinfo/hwinfo_litex.c

@@ -14,14 +14,19 @@
 
 ssize_t z_impl_hwinfo_get_device_id(uint8_t *buffer, size_t length)
 {
-	uint32_t volatile *ptr = (uint32_t volatile *)(DT_INST_REG_ADDR(0));
-	ssize_t end = MIN(length, (DT_INST_REG_SIZE(0) / sizeof(uint32_t)));
-
+	uint32_t addr = DT_INST_REG_ADDR(0);
+	ssize_t end = MIN(length, DT_INST_REG_ADDR(0) / 4 *
+			CONFIG_LITEX_CSR_DATA_WIDTH / 8);
 	for (int i = 0; i < end; i++) {
-		/* In LiteX even though registers are 32-bit wide, each one
-		   contains meaningful data only in the lowest 8 bits */
-		buffer[i] = (uint8_t)(ptr[i] & 0xff);
+#if CONFIG_LITEX_CSR_DATA_WIDTH == 8
+		buffer[i] = litex_read8(addr);
+		addr += 4;
+#elif CONFIG_LITEX_CSR_DATA_WIDTH == 32
+		buffer[i] = (uint8_t)(litex_read32(addr) >> (addr % 4 * 8));
+		addr += 1;
+#else
+#error Unsupported CSR data width
+#endif
 	}
-
 	return end;
 }