nvme: Add support for get-reg and set-reg commands

The get-reg command is to output single register.
The set-reg command is to write nvme register.

Signed-off-by: Tokunori Ikegami <ikegami.t@gmail.com>

Author: ikegami-t

common.h

@@ -3,6 +3,7 @@
 #define _COMMON_H
 
 #include <string.h>
+#include <stdbool.h>
 
 #include "ccan/endian/endian.h"
 
@@ -35,4 +36,24 @@ static inline uint64_t mmio_read64(void *addr)
 	return ((uint64_t)high << 32) | low;
 }
 
+static inline void mmio_write32(void *addr, uint32_t value)
+{
+	leint32_t *p = addr;
+
+	*p = cpu_to_le32(value);
+}
+
+/* Access 64-bit registers as 2 32-bit if write32 flag set; Some devices fail 64-bit MMIO. */
+static inline void mmio_write64(void *addr, uint64_t value, bool write32)
+{
+	uint64_t *p = addr;
+
+	if (write32) {
+		mmio_write32(addr, value);
+		mmio_write32((uint32_t *)addr + 1, value >> 32);
+		return;
+	}
+
+	*p = cpu_to_le64(value);
+}
 #endif

nvme-builtin.h

@@ -89,6 +89,8 @@ COMMAND_LIST(
 	ENTRY("subsystem-reset", "Resets the subsystem", subsystem_reset)
 	ENTRY("ns-rescan", "Rescans the NVME namespaces", ns_rescan)
 	ENTRY("show-regs", "Shows the controller registers or properties. Requires character device", show_registers)
+	ENTRY("set-reg", "Set a register and show the resulting value", set_register)
+	ENTRY("get-reg", "Get a register and show the resulting value", get_register)
 	ENTRY("discover", "Discover NVMeoF subsystems", discover_cmd)
 	ENTRY("connect-all", "Discover and Connect to NVMeoF subsystems", connect_all_cmd)
 	ENTRY("connect", "Connect to NVMeoF subsystem", connect_cmd)