early_smbus: Add early SMBus implementation for VIA chipsets

Add a common implementation of SMBus functionality for early chipsets. Note
however, that existing via chipsets are not ported to this code. Porting
will require hardware testing to make sure everything is fine.

This code is used in the VIA VX900 branch.

Change-Id: If5ad8cd0942ac02d358a0139967e7d85d395660f
Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
Reviewed-on: http://review.coreboot.org/144
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>

7 files changed, 292 insertions, 0 deletions

diff --git a/src/southbridge/via/common/early_smbus_delay.c b/src/southbridge/via/common/early_smbus_delay.c
new file mode 100644
index 0000000000..77733561d3
--- /dev/null
+++ b/src/southbridge/via/common/early_smbus_delay.c
@@ -0,0 +1,28 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright (C) 2011-2013  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 "via_early_smbus.h"
+
+/**
+ * \brief Brief delay for SMBus transactions
+ */
+void smbus_delay(void)
+{
+	inb(0x80);
+}
diff --git a/src/southbridge/via/common/early_smbus_is_busy.c b/src/southbridge/via/common/early_smbus_is_busy.c
new file mode 100644
index 0000000000..1462141210
--- /dev/null
+++ b/src/southbridge/via/common/early_smbus_is_busy.c
@@ -0,0 +1,31 @@
+/*
+ * 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 "via_early_smbus.h"
+
+/**
+ * \brief Checks if the SMBus is currently busy with a transaction
+ *
+ * @param smbus_dev The base SMBus IO port
+ */
+int smbus_is_busy(u32 smbus_dev)
+{
+	/* Check if bit 0 of the status register is 1 (busy) or 0 (ready) */
+	return ((inb(SMBHSTSTAT(smbus_dev)) & (1 << 0)) == 1);
+}
diff --git a/src/southbridge/via/common/early_smbus_print_error.c b/src/southbridge/via/common/early_smbus_print_error.c
new file mode 100644
index 0000000000..7b30a71c6e
--- /dev/null
+++ b/src/southbridge/via/common/early_smbus_print_error.c
@@ -0,0 +1,53 @@
+/*
+ * 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 "via_early_smbus.h"
+#include <console/console.h>
+
+/**
+ * \brief Print an error, should it occur. If no error, just exit.
+ *
+ * @param smbus_dev The base SMBus IO port
+ * @param host_status The data returned on the host status register after
+ *		      a transaction is processed.
+ * @param loops The number of times a transaction was attempted.
+ * @return	0 if no error occurred
+ * 		1 if an error was detected
+ */
+int smbus_print_error(u32 smbus_dev, u8 host_status, int loops)
+{
+	/* Check if there actually was an error. */
+	if ((host_status == 0x00 || host_status == 0x40 ||
+	     host_status == 0x42) && (loops < SMBUS_TIMEOUT))
+		return 0;
+
+	if (loops >= SMBUS_TIMEOUT)
+		printsmbus("SMBus timeout\n");
+	if (host_status & (1 << 4))
+		printsmbus("Interrupt/SMI# was Failed Bus Transaction\n");
+	if (host_status & (1 << 3))
+		printsmbus("Bus error\n");
+	if (host_status & (1 << 2))
+		printsmbus("Device error\n");
+	if (host_status & (1 << 1))
+		printsmbus("Interrupt/SMI# completed successfully\n");
+	if (host_status & (1 << 0))
+		printsmbus("Host busy\n");
+	return 1;
+}
diff --git a/src/southbridge/via/common/early_smbus_read_byte.c b/src/southbridge/via/common/early_smbus_read_byte.c
new file mode 100644
index 0000000000..de76ac9175
--- /dev/null
+++ b/src/southbridge/via/common/early_smbus_read_byte.c
@@ -0,0 +1,51 @@
+/*
+ * 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 "via_early_smbus.h"
+
+/**
+ * \brief Read a byte from the SMBus.
+ *
+ * @param smbus_dev The base SMBus IO port
+ * @param addr The address location of the DIMM on the SMBus.
+ * @param offset The offset the data is located at.
+ */
+u8 smbus_read_byte(u32 smbus_dev, u8 addr, u8 offset)
+{
+	u8 val;
+
+	/* Initialize SMBus sequence */
+	smbus_reset(smbus_dev);
+	/* Clear host data port. */
+	outb(0x00, SMBHSTDAT0(smbus_dev));
+
+	smbus_wait_until_ready(smbus_dev);
+
+	/* Actual addr to reg format. */
+	addr = (addr << 1);
+	addr |= 1;		/* read command */
+	outb(addr, SMBXMITADD(smbus_dev));
+	outb(offset, SMBHSTCMD(smbus_dev));
+	/* Start transaction, byte data read. */
+	outb(0x48, SMBHSTCTL(smbus_dev));
+	smbus_wait_until_ready(smbus_dev);
+
+	val = inb(SMBHSTDAT0(smbus_dev));
+	return val;
+}
diff --git a/src/southbridge/via/common/early_smbus_reset.c b/src/southbridge/via/common/early_smbus_reset.c
new file mode 100644
index 0000000000..68cdd4f75a
--- /dev/null
+++ b/src/southbridge/via/common/early_smbus_reset.c
@@ -0,0 +1,30 @@
+/*
+ * 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 "via_early_smbus.h"
+
+/**
+ * \brief Clear the SMBus host status register
+ *
+ * @param smbus_dev The base SMBus IO port
+ */
+void smbus_reset(u32 smbus_dev)
+{
+	outb(0xdf, SMBHSTSTAT(smbus_dev));
+}
diff --git a/src/southbridge/via/common/early_smbus_wait_until_ready.c b/src/southbridge/via/common/early_smbus_wait_until_ready.c
new file mode 100644
index 0000000000..dba37ff0cd
--- /dev/null
+++ b/src/southbridge/via/common/early_smbus_wait_until_ready.c
@@ -0,0 +1,43 @@
+/*
+ * 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 "via_early_smbus.h"
+#include <console/console.h>
+
+/**
+ * \brief Wait for the SMBus to become ready to process a new transaction.
+ *
+ * @param smbus_dev The base SMBus IO port
+ */
+int smbus_wait_until_ready(u32 smbus_dev)
+{
+	int loops;
+
+	printsmbus("Waiting until SMBus ready\n");
+
+	/* Loop up to SMBUS_TIMEOUT times, waiting for bit 0 of the
+	 * SMBus Host Status register to go to 0, indicating the operation
+	 * was completed successfully. I don't remember why I did it this way,
+	 * but I think it was because ROMCC was running low on registers */
+	loops = 0;
+	while (smbus_is_busy(smbus_dev) && loops < SMBUS_TIMEOUT)
+		++loops;
+
+	return smbus_print_error(smbus_dev, inb(SMBHSTSTAT(smbus_dev)), loops);
+}
diff --git a/src/southbridge/via/common/via_early_smbus.h b/src/southbridge/via/common/via_early_smbus.h
new file mode 100644
index 0000000000..aca920b470
--- /dev/null
+++ b/src/southbridge/via/common/via_early_smbus.h
@@ -0,0 +1,56 @@
+/*
+ * 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/>.
+ */
+
+/**
+ * @file via_early_sambus.h
+ *
+ * This file contains generic definitions used in VIA SMBus controllers.
+ *
+ * Functions defined in device/early/smbus.h are each implemented in a separate
+ * early_smbus_[func_name].c file. This makes it possible to override any of
+ * these functions by not including them in yout build, via Makefile.c. This is
+ * useful when there is a need to work around chipset bugs.
+ *
+ * These implementations work with most via chipsets. Any VIA port should try
+ * to use these. Makefile.inc needs to be adapted to link against the files
+ * providing SMBus functionality:
+ * @code
+ *	romstage-y += ./../../../southbridge/via/common/early_smbus_func.c
+ * @endcode
+ */
+
+/**
+ * \brief SMBus IO ports in relation to the base IO port
+ */
+#define SMBHSTSTAT(base)		((u16)base + 0x0)
+#define SMBSLVSTAT(base)		((u16)base + 0x1)
+#define SMBHSTCTL(base)			((u16)base + 0x2)
+#define SMBHSTCMD(base)			((u16)base + 0x3)
+#define SMBXMITADD(base)		((u16)base + 0x4)
+#define SMBHSTDAT0(base)		((u16)base + 0x5)
+#define SMBHSTDAT1(base)		((u16)base + 0x6)
+#define SMBBLKDAT(base)			((u16)base + 0x7)
+#define SMBSLVCTL(base)			((u16)base + 0x8)
+#define SMBTRNSADD(base)		((u16)base + 0x9)
+#define SMBSLVDATA (base)		((u16)base + 0xa)
+
+#define SMBUS_TIMEOUT			(100*1000*10)
+
+#include <device/early_smbus.h>
+#include <arch/io.h>