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hw/nvram: at24 return 0xff if 1 byte address

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The at24 eeproms are 2 byte devices that return 0xff when they are read
from with a partial (1-byte) address written.  This distinction was
found comparing model behavior to real hardware testing.

Tested: `i2ctransfer -f -y 45 w1@85 0 r1` returns 0xff instead of next
byte

Signed-off-by: Patrick Venture <venture@google.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20211220212137.1244511-1-venture@google.com>
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
This commit is contained in:
Patrick Venture 2021-12-20 13:21:37 -08:00 committed by Philippe Mathieu-Daudé
parent 15df33ceb7
commit 1cbab82e9d
1 changed files with 6 additions and 1 deletions
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7
hw/nvram/eeprom_at24c.c
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@ -58,9 +58,10 @@ int at24c_eeprom_event(I2CSlave *s, enum i2c_event event)
switch (event) {
case I2C_START_SEND:
case I2C_START_RECV:
case I2C_FINISH:
ee->haveaddr = 0;
/* fallthrough */
case I2C_START_RECV:
DPRINTK("clear\n");
if (ee->blk && ee->changed) {
int len = blk_pwrite(ee->blk, 0, ee->mem, ee->rsize, 0);
@ -84,6 +85,10 @@ uint8_t at24c_eeprom_recv(I2CSlave *s)
EEPROMState *ee = AT24C_EE(s);
uint8_t ret;
if (ee->haveaddr == 1) {
return 0xff;
}
ret = ee->mem[ee->cur];
ee->cur = (ee->cur + 1u) % ee->rsize;