Re: [PATCH 1/3] i386: CS5535 chip support - cpu
From: Jordan Crouse
Date: Wed Dec 07 2005 - 14:42:08 EST
Greetings Ben -
> - verifies the existence of the CS5535 by checking the DIVIL signature
> - configures UART1 as a NS16550A
I'm confused by all this. Not so much your code, which is correct, but
your reason for doing all of this in the first place. On a somewhat sane
BIOS, it should have already set up all your descriptors and GPIO pins
long before the kernel booted. Not that you should trust blindly the BIOS
in all things, but as long as this is handled for you, you might as well take
advantage of it.
Now, if your particular board has its own very good reasons for handling
this, then thats fine, but I don't think this should be accepted as CS5535
support, because it stands a fairly good chance of causing trouble over
the larger set of Geode devices. I'll certainly listen to arguments
to the contrary, though.
> - (optionally) enables UART2 and configures it as a NS16550A
This is similar to code that has previously been submitted, and is attached
below. Please review and comment.
> - (optionally) enables the SMBus/I2C interface
Is there any reason why you can't use the PCI devices instead? Granted,
the SMBUS and GPIO are part of a multi-function device (which has a higher
annoyance level), but it still seems better then passing around the global
variables that you read from the MSR. Also, PCI has the advantage of being
a much cleaner and well traveled path, which is always nice.
Regards,
Jordan
--
Jordan Crouse
Senior Linux Engineer
AMD - Personal Connectivity Solutions Group
<www.amd.com/embeddedprocessors>
GEODE: Support second UART on CS5535
The CS5535 has a muxed serial port that can either be used to drive GPIO pins
or a second 16550 UART. This code enables the UART via a command line option.
Signed-off-by: Jordan Crouse <jordan.crouse@xxxxxxx>
---
drivers/serial/Kconfig | 11 ++++++
drivers/serial/Makefile | 1 +
drivers/serial/cs5535_uart.c | 83 ++++++++++++++++++++++++++++++++++++++++++
3 files changed, 95 insertions(+), 0 deletions(-)
diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig
index ad47c1b..0b1bb39 100644
--- a/drivers/serial/Kconfig
+++ b/drivers/serial/Kconfig
@@ -616,6 +616,17 @@ config SERIAL_AU1X00_CONSOLE
If you have an Alchemy AU1X00 processor (MIPS based) and you want
to use a console on a serial port, say Y. Otherwise, say N.
+config SERIAL_GEODE_UART2
+ bool "Enable AMD CS5535 UART2 as a serial port"
+ depends on MGEODE_LX
+ default y
+ select SERIAL_CORE
+ help
+ Select this to allow the user to select the secondary CS5535 UART
+ as a 16550 serial port instead of the default DDC interface. The
+ UART2 can be selected by specifying geodeuart2 on the command
+ line.
+
config SERIAL_CORE
tristate
diff --git a/drivers/serial/Makefile b/drivers/serial/Makefile
index d7c7c71..16dee50 100644
--- a/drivers/serial/Makefile
+++ b/drivers/serial/Makefile
@@ -57,3 +57,4 @@ obj-$(CONFIG_SERIAL_JSM) += jsm/
obj-$(CONFIG_SERIAL_TXX9) += serial_txx9.o
obj-$(CONFIG_SERIAL_VR41XX) += vr41xx_siu.o
obj-$(CONFIG_SERIAL_SGI_IOC4) += ioc4_serial.o
+obj-$(CONFIG_SERIAL_GEODE_UART2) += cs5535_uart.o
diff --git a/drivers/serial/cs5535_uart.c b/drivers/serial/cs5535_uart.c
new file mode 100644
index 0000000..d77c178
--- /dev/null
+++ b/drivers/serial/cs5535_uart.c
@@ -0,0 +1,83 @@
+/*
+ * Copyright (c) 2004-2005 Advanced Micro Devices, 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; 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, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ * The full GNU General Public License is included in this distribution in the
+ * file called COPYING
+ */
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <asm/msr.h>
+#include <asm/io.h>
+
+/* The CS5535 companion chip has two UARTs. This code enables the second
+ UART so other devices can use it. We do it here so we can expose the
+ port early enough for serial debugging
+*/
+
+/* Note - this does not check to see if the CS5535 actually exists */
+
+#define LO(b) (((1 << b) << 16) | 0x0000)
+#define HI(b) ((0x0000 << 16) | (1 << b))
+
+static u32 outtab[16] __initdata =
+{
+ 0x00,HI(4), 0x04,HI(4), 0x08,HI(4),
+ 0x0c,LO(4), 0x10,HI(4), 0x14,LO(4),
+ 0x18,LO(4), 0x1C,LO(4)
+};
+
+static u32 intab[16] __initdata = {
+ 0x20,HI(3), 0x24,LO(3), 0x28,LO(3),
+ 0x2C,LO(3), 0x34,HI(3), 0x38,LO(3),
+ 0x40,LO(3), 0x44,LO(3)
+};
+
+static int __init init_cs5535_uart2(char *str)
+{
+ u32 lo = 0, hi = 0;
+ u32 base; u32 i;
+
+ /* Enable UART2 instead of DDC */
+
+ rdmsr(0x51400014, lo, hi);
+ lo &= 0xFF8FFFFF;
+ lo |= 0x00500000; /* 0x2F8 ttyS1 */
+ wrmsr(0x51400014, lo, hi);
+
+ /* Set up the UART registers */
+ wrmsr(0x5140003E, 0x12, 0x00);
+
+ rdmsr(0x5140000C, lo, hi);
+ base = (u32)(lo & 0xFF00);
+
+ /* Enable the GPIO pins (in and out) */
+
+ for(i = 0; i < 16; i += 2) {
+ outl(outtab[i + 1], base + outtab[i]);
+ outl(intab[i + 1], base + intab[i]);
+ }
+
+ /* Enable the IRQ */
+
+ rdmsr(0x51400021,lo,hi);
+ lo &= 0x0FFFFFFF;
+ lo |= 0x30000000; /* IRQ 3 */
+ wrmsr(0x51400021,lo,hi);
+}
+
+__setup("geodeuart2", init_cs5535_uart2);
-
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