hw/nvram/eeprom_at24c: Add init_rom field and at24c_eeprom_init_rom helper

Allows users to specify binary data to initialize an EEPROM, allowing users to
emulate data programmed at manufacturing time.

- Added init_rom and init_rom_size attributes to TYPE_AT24C_EE
- Added at24c_eeprom_init_rom helper function to initialize attributes
- If -drive property is provided, it overrides init_rom data

Signed-off-by: Peter Delevoryas <peter@pjd.dev>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Reviewed-by: Corey Minyard <cminyard@mvista.com>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Tested-by: Ninad Palsule <ninadpalsule@us.ibm.com>
Link: https://lore.kernel.org/r/20230128060543.95582-4-peter@pjd.dev
Signed-off-by: Cédric Le Goater <clg@kaod.org>

hw/nvram/eeprom_at24c.c

@@ -50,6 +50,9 @@ struct EEPROMState {
     uint8_t *mem;
 
     BlockBackend *blk;
+
+    const uint8_t *init_rom;
+    uint32_t init_rom_size;
 };
 
 static
@@ -131,19 +134,37 @@ int at24c_eeprom_send(I2CSlave *s, uint8_t data)
 
 I2CSlave *at24c_eeprom_init(I2CBus *bus, uint8_t address, uint32_t rom_size)
 {
-    I2CSlave *i2c_dev = i2c_slave_new(TYPE_AT24C_EE, address);
+    return at24c_eeprom_init_rom(bus, address, rom_size, NULL, 0);
-    DeviceState *dev = DEVICE(i2c_dev);
+}
 
-    qdev_prop_set_uint32(dev, "rom-size", rom_size);
+I2CSlave *at24c_eeprom_init_rom(I2CBus *bus, uint8_t address, uint32_t rom_size,
-    i2c_slave_realize_and_unref(i2c_dev, bus, &error_abort);
+                                const uint8_t *init_rom, uint32_t init_rom_size)
+{
+    EEPROMState *s;
 
-    return i2c_dev;
+    s = AT24C_EE(i2c_slave_new(TYPE_AT24C_EE, address));
+
+    qdev_prop_set_uint32(DEVICE(s), "rom-size", rom_size);
+
+    /* TODO: Model init_rom with QOM properties. */
+    s->init_rom = init_rom;
+    s->init_rom_size = init_rom_size;
+
+    i2c_slave_realize_and_unref(I2C_SLAVE(s), bus, &error_abort);
+
+    return I2C_SLAVE(s);
 }
 
 static void at24c_eeprom_realize(DeviceState *dev, Error **errp)
 {
     EEPROMState *ee = AT24C_EE(dev);
 
+    if (ee->init_rom_size > ee->rsize) {
+        error_setg(errp, "%s: init rom is larger than rom: %u > %u",
+                   TYPE_AT24C_EE, ee->init_rom_size, ee->rsize);
+        return;
+    }
+
     if (ee->blk) {
         int64_t len = blk_getlength(ee->blk);
 
@@ -163,6 +184,7 @@ static void at24c_eeprom_realize(DeviceState *dev, Error **errp)
     }
 
     ee->mem = g_malloc0(ee->rsize);
+
 }
 
 static
@@ -176,6 +198,10 @@ void at24c_eeprom_reset(DeviceState *state)
 
     memset(ee->mem, 0, ee->rsize);
 
+    if (ee->init_rom) {
+        memcpy(ee->mem, ee->init_rom, MIN(ee->init_rom_size, ee->rsize));
+    }
+
     if (ee->blk) {
         int ret = blk_pread(ee->blk, 0, ee->rsize, ee->mem, 0);
 

include/hw/nvram/eeprom_at24c.h

@@ -20,4 +20,20 @@
  */
 I2CSlave *at24c_eeprom_init(I2CBus *bus, uint8_t address, uint32_t rom_size);
 
+
+/*
+ * Create and realize an AT24C EEPROM device on the heap with initial data.
+ * @bus: I2C bus to put it on
+ * @address: I2C address of the EEPROM slave when put on a bus
+ * @rom_size: size of the EEPROM
+ * @init_rom: Array of bytes to initialize EEPROM memory with
+ * @init_rom_size: Size of @init_rom, must be less than or equal to @rom_size
+ *
+ * Create the device state structure, initialize it, put it on the specified
+ * @bus, and drop the reference to it (the device is realized). Copies the data
+ * from @init_rom to the beginning of the EEPROM memory buffer.
+ */
+I2CSlave *at24c_eeprom_init_rom(I2CBus *bus, uint8_t address, uint32_t rom_size,
+                                const uint8_t *init_rom, uint32_t init_rom_size);
+
 #endif