common/block/imc: Add Integrated Memory Controller (IMC) driver

IMC is found on certain Xeon processors. On such platforms SPDs are not
connected to SMBus on PCH but to dedicated IMC-owned pins. The purpose
of this driver is to expose access to the i2c/smbus controller associated
with IMC.

Datasheet used: Intel Xeon Processor D-1500 Product Family, Volume 2,
reference 332051-001

This driver is largely based on i2c-imc.c Linux driver.
https://lwn.net/Articles/685475/

TEST=single/double reads and single writes on Xeon-D1500.
Hardware: Open Compute Project Monolake platform.

Signed-off-by: Andrey Petrov <anpetrov@fb.com>
Change-Id: Idbcda1c2273b9a5721fcd9470b4de182192779e7
Reviewed-on: https://review.coreboot.org/c/coreboot/+/34678
Reviewed-by: David Hendricks <david.hendricks@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

4 files changed, 225 insertions, 0 deletions

diff --git a/src/soc/intel/common/block/imc/Kconfig b/src/soc/intel/common/block/imc/Kconfig
new file mode 100644
index 0000000000..490b80ebeb
--- /dev/null
+++ b/src/soc/intel/common/block/imc/Kconfig
@@ -0,0 +1,7 @@
+config SOC_INTEL_COMMON_BLOCK_IMC
+	bool
+	depends on MMCONF_SUPPORT
+	default n
+	help
+	  Driver for communication with Integrated Memory Controller that is found on
+	  some Xeon server processors.
diff --git a/src/soc/intel/common/block/imc/Makefile.inc b/src/soc/intel/common/block/imc/Makefile.inc
new file mode 100644
index 0000000000..a6bc985eb2
--- /dev/null
+++ b/src/soc/intel/common/block/imc/Makefile.inc
@@ -0,0 +1,9 @@
+ifeq ($(CONFIG_SOC_INTEL_COMMON_BLOCK_IMC),y)
+
+bootblock-y += imc.c
+romstage-y += imc.c
+verstage-y += imc.c
+postcar-y += imc.c
+ramstage-y += imc.c
+
+endif
diff --git a/src/soc/intel/common/block/imc/imc.c b/src/soc/intel/common/block/imc/imc.c
new file mode 100644
index 0000000000..e7f20bef03
--- /dev/null
+++ b/src/soc/intel/common/block/imc/imc.c
@@ -0,0 +1,171 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright 2019 Facebook, Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+/*
+ * Please note: the driver uses MMIO PCIe register access. IO based access will
+ * not work.
+ */
+
+#include <console/console.h>
+#include <delay.h>
+#include <device/pci_ops.h>
+#include <intelblocks/imc.h>
+#include <soc/pci_devs.h>
+#include <timer.h>
+
+#define IMC_SMBUS_TIMEOUT_MS           100
+#define IMC_SMBCNTL_DTI_TSOD           0x3
+#define IMC_SMBCNTL_DTI_EEPROM         0xa
+#define IMC_SMBCNTL_DTI_WP_EEPROM      0x6
+
+#define SMBSTAT(i)                     (0x180 + 0x10 * i)
+#define SMBCMD(i)                      (0x184 + 0x10 * i)
+#define SMBCNTL(i)                     (0x188 + 0x10 * i)
+
+#define SMBSTAT_RDO                    (1u << 31)  /* Read Data Valid */
+#define SMBSTAT_WOD                    (1u << 30)  /* Write Operation Done */
+#define SMBSTAT_SBE                    (1u << 29)  /* SMBus Error */
+#define SMBSTAT_SMB_BUSY               (1u << 28)  /* SMBus Busy State */
+
+#define SMBCMD_TRIGGER                 (1u << 31)  /* CMD Trigger */
+#define SMBCMD_PNTR_SEL                (1u << 30)  /* HW polls TSOD with pointer */
+#define SMBCMD_WORD_ACCESS             (1u << 29)  /* word (vs byte) access */
+#define SMBCMD_TYPE_MASK               (3u << 27)  /* Mask for access type */
+#define SMBCMD_TYPE_READ               (0u << 27)  /* Read */
+#define SMBCMD_TYPE_WRITE              (1u << 27)  /* Write */
+#define SMBCMD_TYPE_PNTR_WRITE         (3u << 27)  /* Write to pointer */
+#define SMBCMD_SA_MASK                 (7u << 24)  /* Slave Address high bits */
+#define SMBCMD_SA_SHIFT                24
+#define SMBCMD_BA_MASK                 0xff0000    /* Bus Txn address */
+#define SMBCMD_BA_SHIFT                16
+#define SMBCMD_WDATA_MASK              0xffff      /* data to write */
+
+#define SMBCNTL_DTI_MASK               0xf0000000  /* Slave Address low bits */
+#define SMBCNTL_DTI_SHIFT              28          /* Slave Address low bits */
+#define SMBCNTL_CKOVRD                 (1u << 27)  /* # Clock Override */
+#define SMBCNTL_DIS_WRT                (1u << 26)  /* Disable Write (sadly) */
+#define SMBCNTL_SOFT_RST               (1u << 10)  /* Soft Reset */
+#define SMBCNTL_TSOD_POLL_EN           (1u << 8)   /* TSOD Polling Enable */
+
+static bool poll_ready(pci_devfn_t dev, enum memory_controller_id mcid, uint32_t *status)
+{
+	struct stopwatch sw;
+
+	stopwatch_init_msecs_expire(&sw, IMC_SMBUS_TIMEOUT_MS);
+
+	do {
+		*status = pci_mmio_read_config32(dev, SMBSTAT(mcid));
+		if (!(*status & SMBSTAT_SMB_BUSY))
+			break;
+	} while (!stopwatch_expired(&sw));
+
+	return (!(*status & SMBSTAT_SMB_BUSY));
+}
+
+static bool claim_controller(pci_devfn_t dev, enum memory_controller_id mcid)
+{
+	uint32_t cntl, status;
+
+	cntl = pci_mmio_read_config32(dev, SMBCNTL(mcid));
+	cntl &= ~SMBCNTL_TSOD_POLL_EN;
+	cntl &= ~SMBCNTL_DIS_WRT;
+	pci_mmio_write_config32(dev, SMBCNTL(mcid), cntl);
+
+	return poll_ready(dev, mcid, &status);
+}
+
+
+static void release_controller(pci_devfn_t dev, enum memory_controller_id mcid)
+{
+	uint32_t cntl, status;
+
+	cntl = pci_mmio_read_config32(dev, SMBCNTL(mcid));
+	cntl |= SMBCNTL_TSOD_POLL_EN;
+	pci_mmio_write_config32(dev, SMBCNTL(mcid), cntl);
+
+	poll_ready(dev, mcid, &status);
+}
+
+int imc_smbus_spd_xfer(pci_devfn_t dev, uint8_t slave_addr, uint8_t bus_addr,
+		       enum device_type_id dti, enum access_width width,
+		       enum memory_controller_id mcid, enum smbus_command cmd, void *data)
+{
+	int ret = -1;
+	uint32_t cmdbits = 0, stat = 0, cntlbits = 0, data_mask = 0;
+	uint16_t wdata = 0, rdata = 0;
+
+	/* slaves addresses are 7 bits length */
+	if (slave_addr > (1 << 7) - 1) {
+		printk(BIOS_ERR, "invalid SMBus address, aborting xfer\n");
+		return -1;
+	}
+
+	if (!claim_controller(dev, mcid)) {
+		printk(BIOS_ERR, "ayee! couldn't claim controller, giving up xfer\n");
+		return -1;
+	}
+
+	cmdbits = (slave_addr << SMBCMD_SA_SHIFT);
+	cmdbits |= (bus_addr << SMBCMD_BA_SHIFT);
+
+	if (cmd == IMC_WRITE) {
+		wdata = (width == IMC_DATA_BYTE ? read8(data) : cpu_to_be16(read16(data)));
+		cmdbits |= (SMBCMD_TYPE_WRITE | wdata);
+	} else {
+		cmdbits |= SMBCMD_TYPE_READ;
+	}
+
+	if (width == IMC_DATA_WORD) {
+		cmdbits |= SMBCMD_WORD_ACCESS;
+		data_mask = 0xffff;
+	} else {
+		data_mask = 0xff;
+	}
+
+	cntlbits = pci_mmio_read_config32(dev, SMBCNTL(mcid));
+	cntlbits &= ~SMBCNTL_DTI_MASK;
+	cntlbits |= (dti << SMBCNTL_DTI_SHIFT);
+
+	pci_mmio_write_config32(dev, SMBCNTL(mcid), cntlbits);
+
+	/* Pull the trigger */
+	cmdbits |= SMBCMD_TRIGGER;
+	pci_mmio_write_config32(dev, SMBCMD(mcid), cmdbits);
+
+	if (!poll_ready(dev, mcid, &stat)) {
+		printk(BIOS_ERR, "IMC xfer failed for slave %x", slave_addr);
+		ret = -1;
+		goto cleanup;
+	}
+
+	if (stat & SMBSTAT_SBE) {
+		ret = -1;
+		goto cleanup;
+	}
+
+	if (cmd == IMC_READ) {
+		rdata = stat & data_mask;
+		if (width == IMC_DATA_WORD)
+			write16(data, cpu_to_be16(rdata));
+		else
+			write8(data, rdata);
+	}
+
+	ret = 0;
+cleanup:
+	release_controller(dev, SMBSTAT(mcid));
+
+	return ret;
+}
diff --git a/src/soc/intel/common/block/include/intelblocks/imc.h b/src/soc/intel/common/block/include/intelblocks/imc.h
new file mode 100644
index 0000000000..fc3c241564
--- /dev/null
+++ b/src/soc/intel/common/block/include/intelblocks/imc.h
@@ -0,0 +1,38 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright 2019 Facebook, Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <device/pci.h>
+#include <stdint.h>
+
+#ifndef SOC_INTEL_COMMON_BLOCK_IMC_H
+#define SOC_INTEL_COMMON_BLOCK_IMC_H
+
+enum smbus_command { IMC_READ, IMC_WRITE };
+
+enum access_width { IMC_DATA_BYTE, IMC_DATA_WORD };
+
+enum memory_controller_id { IMC_CONTROLLER_ID0 = 0, IMC_CONTROLLER_ID1 };
+
+enum device_type_id {
+	IMC_DEVICE_TSOD = 0x3,
+	IMC_DEVICE_WP_EEPROM = 0x6,
+	IMC_DEVICE_EEPROM = 0xa
+};
+
+/* Initiate SMBus/I2C transaction to DIMM EEPROM */
+int imc_smbus_spd_xfer(pci_devfn_t dev, uint8_t slave_addr, uint8_t bus_addr,
+		       enum device_type_id dti, enum access_width width,
+		       enum memory_controller_id mcid, enum smbus_command cmd, void *data);
+#endif