New patch to review: 9d152c1 coreboot: Add generic SMBUS implementation

[Alexandru Gagniuc]

Alexandru Gagniuc ([e-mail]) just uploaded a new patch set to gerrit, which you can find at http://review.coreboot.org/143

-gerrit

commit 9d152c129b6f9fdd084185ed67cc1fc31529ad74
Author: Alexandru Gagniuc 
Date:   Tue Aug 9 01:26:52 2011 -0500

coreboot: Add generic SMBUS implementation

Early SMBUS code with similar functionality is duplicated for all
    southbridges. Add a generic SMBUS implementation, with functions
    declared weak, so that they can be overridden by the southbridge
    code if necessary.

Change-Id: I0861b7a3f098115182ae6de9f016dd671c500bad
    Signed-off-by: Alexandru Gagniuc 
---
 src/devices/smbus/early_smbus.c |  141 +++++++++++++++++++++++++++++++++++++++
 src/devices/smbus/smbus.h       |  100 +++++++++++++++++++++++++++
 2 files changed, 241 insertions(+), 0 deletions(-)

diff --git a/src/devices/smbus/early_smbus.c b/src/devices/smbus/early_smbus.c
new file mode 100644
index 0000000..4583aca
--- /dev/null
+++ b/src/devices/smbus/early_smbus.c
@@ -0,0 +1,141 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright (C) 2011  Alexandru Gagniuc 
+ *
+ * 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 post_codes.h
+ *
+ * This file defines the implementations for the functions defined in smbus.h
+ * These are a generic SMBUS implementation, which should work with a majority
+ * of chipsets.
+ * They are marked weak so that they can be overridden by the chipset code if
+ * necessary.
+ */
+
+#include "smbus.h"
+
+/**
+ * \brief Brief delay for SMBUS transactions
+ */
+__attribute__((weak))
+void __smbus_delay(void)
+{
+	inb(0x80);
+}
+
+/**
+ * \brief Clear the SMBUS host status register
+ */
+__attribute__((weak))
+void __smbus_reset(u16 __smbus_io_base)
+{
+	outb(0xdf, SMBHSTSTAT);
+}
+
+/**
+ * \brief Print an error, should it occur. If no error, just exit.
+ *
+ * @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
+ */
+__attribute__((weak))
+int __smbus_print_error(u8 host_status, int loops, u16 __smbus_io_base)
+{
+	/* 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;
+}
+
+/**
+ * \brief Checks if the SMBUS is currently busy with a transaction
+ */
+__attribute__((weak))
+int __smbus_is_busy(u16 __smbus_io_base)
+{
+	/* Check if bit 0 of the status register is 1 (busy) or 0 (ready) */
+	return ( (inb(SMBHSTSTAT) & (1 << 0)) == 1);
+}
+
+/**
+ * \brief Wait for the SMBUS to become ready to process a new transaction.
+ */
+__attribute__((weak))
+int __smbus_wait_until_ready(u16 __smbus_io_base)
+{
+	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_io_base) && loops < SMBUS_TIMEOUT)
+		++loops;
+	
+	return __smbus_print_error(inb(SMBHSTSTAT), loops, __smbus_io_base);
+}
+
+/**
+ * \brief Read a byte from the SMBUS.
+ *
+ * @param dimm The address location of the DIMM on the SMBus.
+ * @param offset The offset the data is located at.
+ */
+__attribute__((weak))
+u8 __smbus_read_byte(u8 dimm, u8 offset, u16 __smbus_io_base)
+{
+	u8 val;
+	
+	/* Initialize SMBUS sequence */
+	__smbus_reset(__smbus_io_base);
+	/* Clear host data port. */
+	outb(0x00, SMBHSTDAT0);
+	
+	__smbus_wait_until_ready(__smbus_io_base);
+	
+	/* Actual addr to reg format. */
+	dimm = (dimm << 1);
+	dimm |= 1; /* read command */
+	outb(dimm, SMBXMITADD);
+	outb(offset, SMBHSTCMD);
+	/* Start transaction, byte data read. */
+	outb(0x48, SMBHSTCTL);
+	__smbus_wait_until_ready(__smbus_io_base);
+	
+	val = inb(SMBHSTDAT0);
+	return val;
+}
\ No newline at end of file
diff --git a/src/devices/smbus/smbus.h b/src/devices/smbus/smbus.h
new file mode 100644
index 0000000..c730669
--- /dev/null
+++ b/src/devices/smbus/smbus.h
@@ -0,0 +1,100 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright (C) 2011  Alexandru Gagniuc 
+ *
+ * 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 post_codes.h
+ *
+ * This file defines the prototypes for several common SMBUS functions
+ * These functions are prefixed with __smbus_ so that they do not conflict with
+ * the dozens of similar (duplicated) implementations in many southbridges.
+ *
+ * As a last parameter, the SMBUS functions take a u16 value __smbus_io_base,
+ * which represents the base IO port for smbus transactions
+ */
+
+#include <arch/io.h>
+
+/**
+ * \brief SMBUS IO ports in relation to the base IO port
+ */
+#define SMBHSTSTAT		__smbus_io_base + 0x0
+#define SMBSLVSTAT		__smbus_io_base + 0x1
+#define SMBHSTCTL		__smbus_io_base + 0x2
+#define SMBHSTCMD		__smbus_io_base + 0x3
+#define SMBXMITADD		__smbus_io_base + 0x4
+#define SMBHSTDAT0		__smbus_io_base + 0x5
+#define SMBHSTDAT1		__smbus_io_base + 0x6
+#define SMBBLKDAT		__smbus_io_base + 0x7
+#define SMBSLVCTL		__smbus_io_base + 0x8
+#define SMBTRNSADD		__smbus_io_base + 0x9
+#define SMBSLVDATA 		__smbus_io_base + 0xa
+
+#define SMBUS_TIMEOUT		(100*1000*10)
+
+/**
+ * \brief printk macro for SMBUS debugging
+ */
+#if defined(CONFIG_DEBUG_SMBUS_SETUP) && (CONFIG_DEBUG_SMBUS_SETUP)
+#define printsmbus(x, ...) printk(BIOS_DEBUG, x, ##__VA_ARGS__)
+#else
+#define printsmbus(x, ...)
+#endif
+
+
+void __smbus_reset(u16 __smbus_io_base);
+int __smbus_print_error(u8 host_status, int loops, u16 __smbus_io_base);
+int __smbus_is_busy(u16 __smbus_io_base);
+int __smbus_wait_until_ready(u16 __smbus_io_base);
+u8 __smbus_read_byte(u8 dimm, u8 offset, u16 __smbus_io_base);
+
+void __smbus_delay(void);
+
+#if defined(SMBUS_IO_BASE) && (SMBUS_IO_BASE != 0)
+
+__attribute__((always_inline, unused))
+static void smbus_reset(void)
+{
+	__smbus_reset(SMBUS_IO_BASE);
+}
+
+__attribute__((always_inline, unused))
+static int smbus_is_busy(void)
+{
+	return __smbus_is_busy(SMBUS_IO_BASE);
+}
+
+__attribute__((always_inline, unused))
+static int smbus_wait_until_ready(void)
+{
+	return __smbus_wait_until_ready(SMBUS_IO_BASE);
+}
+
+__attribute__((always_inline, unused))
+static int smbus_print_error(u8 host_status, int loops)
+{
+	return __smbus_print_error(host_status, loops, SMBUS_IO_BASE);
+}
+
+__attribute__((always_inline, unused))
+static u8 smbus_read_byte(u8 dimm, u8 offset)
+{
+	return __smbus_read_byte(dimm, offset, SMBUS_IO_BASE);
+}
+
+#endif
\ No newline at end of file