VIA VX900: Add minimal ramstage needed to boot linux

This is the minimal code needed to get past ramstage, load SeaBIOS, jump
to GRUB2, and boot linux (or load memtest). See individual source files for
the status of each individual component.

Change-Id: Ib7d5d7593c945f18af2c2fc5e0ae689ba66131a2
Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
Reviewed-on: http://review.coreboot.org/3419
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>

1 files changed, 123 insertions, 0 deletions

diff --git a/src/northbridge/via/vx900/pcie.c b/src/northbridge/via/vx900/pcie.c
new file mode 100644
index 0000000000..109e5c9ffe
--- /dev/null
+++ b/src/northbridge/via/vx900/pcie.c
@@ -0,0 +1,123 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright (C) 2013  Alexandru Gagniuc <mr.nuke.me@gmail.com>
+ *
+ * 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, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <arch/io.h>
+#include <console/console.h>
+#include <device/pci.h>
+#include <device/pciexp.h>
+#include <device/pci_ids.h>
+
+#include "vx900.h"
+
+/**
+ * @file pcie.c
+ *
+ * STATUS:
+ * We do part of the sequence to initialize the PCIE link. The problem is that
+ * the reset signal for each slot is connected to a GPO pin, but We don't know
+ * which GPO pin. We need to figure out which GPIO pin is hooked to which slot,
+ * and have a mechanism to specify this per-mainboard (devicetree.cb).
+ *
+ * There is currently no timeout detection mechanism for when a link comes up.
+ * If the link never comes up, we hang.
+ */
+
+static void vx900_pcie_link_init(device_t dev)
+{
+	u8 reg8;
+	u32 reg32;
+
+	u8 fn = dev->path.pci.devfn & 0x07;
+
+	/* Step 1 : Check for presence of PCIE device */
+	reg8 = pci_read_config8(dev, 0x5a);
+
+	if (reg8 & (1 << 6))
+		printk(BIOS_DEBUG, "Card detected in PEX%i\n", fn);
+	else
+		return;
+
+	/* Step 2: Wait for device to enter L0 state */
+	/* FIXME: implement timeout detection */
+	while (0x8a != pci_read_config8(dev, 0x1c3)) ;
+
+	/* Step 3: Clear PCIe error status, then check for failures */
+	pci_write_config32(dev, 0x104, 0xffffffff);
+	reg32 = pci_read_config32(dev, 0x104);
+	if (0 != reg32) {
+		printk(BIOS_DEBUG, "PEX init error. flags 0x%.8x\n", reg32);
+		return;
+	}
+
+	pci_write_config32(dev, 0x110, 0xffffffff);
+	reg32 = pci_read_config32(dev, 0x110);
+	if (0 != reg32)
+		printk(BIOS_DEBUG, "PEX errors. flags 0x%.8x\n", reg32);
+
+	pci_write_config8(dev, 0xa4, 0xff);
+	if (pci_read_config8(dev, 0x4a) & (1 << 3))
+		print_debug("Unsupported request detected.\n");
+
+	pci_write_config8(dev, 0x15a, 0xff);
+	if (pci_read_config8(dev, 0x15a) & (1 << 1))
+		print_debug("Negotiation pending.\n");
+
+	/* Step 4: Read vendor ID */
+	/* FIXME: Do we want to run through the whole sequence and delay boot
+	 * by several seconds if the device does not respond properly the first
+	 * time? */
+}
+
+static void vx900_pex_dev_set_resources(device_t dev)
+{
+	assign_resources(dev->link_list);
+}
+
+static void vx900_pex_init(device_t dev)
+{
+	/* FIXME: For some reason, PEX0 hangs on init. Find issue, fix it. */
+	if ((dev->path.pci.devfn & 0x7) == 0)
+		return;
+
+	vx900_pcie_link_init(dev);
+}
+
+static struct device_operations vx900_pex_ops = {
+	.read_resources = pci_bus_read_resources,
+	.set_resources = vx900_pex_dev_set_resources,
+	.enable_resources = pci_bus_enable_resources,
+	.init = vx900_pex_init,
+	.scan_bus = pciexp_scan_bridge,
+	.reset_bus = pci_bus_reset,
+};
+
+static const unsigned short pci_device_ids[] = {
+	PCI_DEVICE_ID_VIA_VX900_PEX1,
+	PCI_DEVICE_ID_VIA_VX900_PEX2,
+	PCI_DEVICE_ID_VIA_VX900_PEX3,
+	PCI_DEVICE_ID_VIA_VX900_PEX4,
+	0,
+};
+
+static const struct pci_driver pex_driver __pci_driver = {
+	.ops = &vx900_pex_ops,
+	.vendor = PCI_VENDOR_ID_VIA,
+	.devices = pci_device_ids,
+
+};