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-rw-r--r--src/devices/machine/dimm_spd.cpp110
1 files changed, 110 insertions, 0 deletions
diff --git a/src/devices/machine/dimm_spd.cpp b/src/devices/machine/dimm_spd.cpp
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+++ b/src/devices/machine/dimm_spd.cpp
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+// license:BSD-3-Clause
+// copyright-holders:R. Belmont
+/*
+ DIMM serial presence detect (SPD) readback device
+ by R. Belmont
+
+ Each DIMM contains a small EEPROM with information about the capacity and
+ timings of the module. The EEPROM speaks a version of I2C called SMBus.
+*/
+
+
+#include "emu.h"
+#include "dimm_spd.h"
+
+#define LOG_DATAOUT (1U << 1)
+
+#define VERBOSE (0)
+#include "logmacro.h"
+
+DEFINE_DEVICE_TYPE(DIMM_SPD, dimm_spd_device, "dimm_spd", "DIMM Serial Presence Detect")
+
+dimm_spd_device::dimm_spd_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock) :
+ device_t(mconfig, DIMM_SPD, tag, owner, clock),
+ i2c_hle_interface(mconfig, *this, 0) // address will be overridden by set_address as before
+{
+}
+
+//-------------------------------------------------
+// device_start - device-specific startup
+//-------------------------------------------------
+
+void dimm_spd_device::device_start()
+{
+ std::fill(std::begin(m_data), std::end(m_data), 0);
+
+ m_data[0] = 128; // # of bytes in EEPROM
+ m_data[1] = 8; // log2 of EEPROM size
+ m_data[2] = 4; // 4 is SDRAM, 7 is DDR SDRAM, 8 is DDR2, 11 is DDR3, 12 is DDR4
+ m_data[3] = 12; // # of rows
+ m_data[4] = 8; // # of columns
+ m_data[5] = 1; // # of banks (12/8/1 = 32 MiB)
+ m_data[6] = 64; // data bus width low byte
+ m_data[7] = 0; // data bus width high byte
+ m_data[11] = 0; // non-ECC (1=parity, 2=ECC)
+ m_data[62] = 0x12; // SPD version 1.2
+}
+
+void dimm_spd_device::set_dimm_size(dimm_size_t size)
+{
+ m_size = size;
+
+ switch (size)
+ {
+ case SIZE_4_MIB:
+ m_data[3] = 12; // # of rows
+ m_data[4] = 5; // # of columns
+ m_data[5] = 1; // # of banks
+ break;
+
+ case SIZE_8_MIB:
+ m_data[3] = 12;
+ m_data[4] = 6;
+ m_data[5] = 1;
+ break;
+
+ case SIZE_16_MIB:
+ m_data[3] = 12;
+ m_data[4] = 7;
+ m_data[5] = 1;
+ break;
+
+ case SIZE_32_MIB:
+ m_data[3] = 12;
+ m_data[4] = 8;
+ m_data[5] = 1;
+ break;
+
+ case SIZE_64_MIB:
+ m_data[3] = 12;
+ m_data[4] = 9;
+ m_data[5] = 1;
+ break;
+
+ case SIZE_128_MIB:
+ m_data[3] = 12;
+ m_data[4] = 10;
+ m_data[5] = 1;
+ break;
+
+ case SIZE_256_MIB:
+ m_data[3] = 12;
+ m_data[4] = 10;
+ m_data[5] = 2;
+ break;
+
+ case SIZE_SLOT_EMPTY:
+ break;
+ }
+}
+
+u8 dimm_spd_device::read_data(u16 offset)
+{
+ // i2c_hle_interface auto-increments the address but doesn't wrap it around
+ if (offset >= m_size)
+ {
+ m_data_offset = 0;
+ }
+
+ return m_data[offset];
+}