[PATCH 3.12 059/142] xtensa: xtfpga: fix hardware lockup caused by LCD driver

From: Jiri Slaby
Date: Sat May 16 2015 - 04:10:06 EST

From: Max Filippov <jcmvbkbc@xxxxxxxxx>

3.12-stable review patch. If anyone has any objections, please let me know.

===============

commit 4949009eb8d40a441dcddcd96e101e77d31cf1b2 upstream.

LCD driver is always built for the XTFPGA platform, but its base address
is not configurable, and is wrong for ML605/KC705. Its initialization
locks up KC705 board hardware.

Make the whole driver optional, and its base address and bus width
configurable. Implement 4-bit bus access method.

Signed-off-by: Max Filippov <jcmvbkbc@xxxxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
arch/xtensa/Kconfig | 30 ++++++++++++
arch/xtensa/platforms/xtfpga/Makefile | 3 +-
.../platforms/xtfpga/include/platform/hardware.h | 3 --
.../xtensa/platforms/xtfpga/include/platform/lcd.h | 15 ++++++
arch/xtensa/platforms/xtfpga/lcd.c | 55 +++++++++++++---------
5 files changed, 81 insertions(+), 25 deletions(-)

diff --git a/arch/xtensa/Kconfig b/arch/xtensa/Kconfig
index 8d24dcb7cdac..3b8060e4f1d7 100644
--- a/arch/xtensa/Kconfig
+++ b/arch/xtensa/Kconfig
@@ -289,6 +289,36 @@ menu "Executable file formats"

source "fs/Kconfig.binfmt"

+config XTFPGA_LCD
+ bool "Enable XTFPGA LCD driver"
+ depends on XTENSA_PLATFORM_XTFPGA
+ default n
+ help
+ There's a 2x16 LCD on most of XTFPGA boards, kernel may output
+ progress messages there during bootup/shutdown. It may be useful
+ during board bringup.
+
+ If unsure, say N.
+
+config XTFPGA_LCD_BASE_ADDR
+ hex "XTFPGA LCD base address"
+ depends on XTFPGA_LCD
+ default "0x0d0c0000"
+ help
+ Base address of the LCD controller inside KIO region.
+ Different boards from XTFPGA family have LCD controller at different
+ addresses. Please consult prototyping user guide for your board for
+ the correct address. Wrong address here may lead to hardware lockup.
+
+config XTFPGA_LCD_8BIT_ACCESS
+ bool "Use 8-bit access to XTFPGA LCD"
+ depends on XTFPGA_LCD
+ default n
+ help
+ LCD may be connected with 4- or 8-bit interface, 8-bit access may
+ only be used with 8-bit interface. Please consult prototyping user
+ guide for your board for the correct interface width.
+
endmenu

source "net/Kconfig"
diff --git a/arch/xtensa/platforms/xtfpga/Makefile b/arch/xtensa/platforms/xtfpga/Makefile
index b9ae206340cd..7839d38b2337 100644
--- a/arch/xtensa/platforms/xtfpga/Makefile
+++ b/arch/xtensa/platforms/xtfpga/Makefile
@@ -6,4 +6,5 @@
#
# Note 2! The CFLAGS definitions are in the main makefile...

-obj-y = setup.o lcd.o
+obj-y += setup.o
+obj-$(CONFIG_XTFPGA_LCD) += lcd.o
diff --git a/arch/xtensa/platforms/xtfpga/include/platform/hardware.h b/arch/xtensa/platforms/xtfpga/include/platform/hardware.h
index 4416773cbde5..b39fbcf5c611 100644
--- a/arch/xtensa/platforms/xtfpga/include/platform/hardware.h
+++ b/arch/xtensa/platforms/xtfpga/include/platform/hardware.h
@@ -44,9 +44,6 @@

/* UART */
#define DUART16552_PADDR (XCHAL_KIO_PADDR + 0x0D050020)
-/* LCD instruction and data addresses. */
-#define LCD_INSTR_ADDR ((char *)IOADDR(0x0D040000))
-#define LCD_DATA_ADDR ((char *)IOADDR(0x0D040004))

/* Misc. */
#define XTFPGA_FPGAREGS_VADDR IOADDR(0x0D020000)
diff --git a/arch/xtensa/platforms/xtfpga/include/platform/lcd.h b/arch/xtensa/platforms/xtfpga/include/platform/lcd.h
index 0e435645af5a..4c8541ed1139 100644
--- a/arch/xtensa/platforms/xtfpga/include/platform/lcd.h
+++ b/arch/xtensa/platforms/xtfpga/include/platform/lcd.h
@@ -11,10 +11,25 @@
#ifndef __XTENSA_XTAVNET_LCD_H
#define __XTENSA_XTAVNET_LCD_H

+#ifdef CONFIG_XTFPGA_LCD
/* Display string STR at position POS on the LCD. */
void lcd_disp_at_pos(char *str, unsigned char pos);

/* Shift the contents of the LCD display left or right. */
void lcd_shiftleft(void);
void lcd_shiftright(void);
+#else
+static inline void lcd_disp_at_pos(char *str, unsigned char pos)
+{
+}
+
+static inline void lcd_shiftleft(void)
+{
+}
+
+static inline void lcd_shiftright(void)
+{
+}
+#endif
+
#endif
diff --git a/arch/xtensa/platforms/xtfpga/lcd.c b/arch/xtensa/platforms/xtfpga/lcd.c
index 2872301598df..4dc0c1b43f4b 100644
--- a/arch/xtensa/platforms/xtfpga/lcd.c
+++ b/arch/xtensa/platforms/xtfpga/lcd.c
@@ -1,50 +1,63 @@
/*
- * Driver for the LCD display on the Tensilica LX60 Board.
+ * Driver for the LCD display on the Tensilica XTFPGA board family.
+ * http://www.mytechcorp.com/cfdata/productFile/File1/MOC-16216B-B-A0A04.pdf
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (C) 2001, 2006 Tensilica Inc.
+ * Copyright (C) 2015 Cadence Design Systems Inc.
*/

-/*
- *
- * FIXME: this code is from the examples from the LX60 user guide.
- *
- * The lcd_pause function does busy waiting, which is probably not
- * great. Maybe the code could be changed to use kernel timers, or
- * change the hardware to not need to wait.
- */
-
+#include <linux/delay.h>
#include <linux/init.h>
#include <linux/io.h>

#include <platform/hardware.h>
#include <platform/lcd.h>
-#include <linux/delay.h>

-#define LCD_PAUSE_ITERATIONS 4000
+/* LCD instruction and data addresses. */
+#define LCD_INSTR_ADDR ((char *)IOADDR(CONFIG_XTFPGA_LCD_BASE_ADDR))
+#define LCD_DATA_ADDR (LCD_INSTR_ADDR + 4)
+
#define LCD_CLEAR 0x1
#define LCD_DISPLAY_ON 0xc

/* 8bit and 2 lines display */
#define LCD_DISPLAY_MODE8BIT 0x38
+#define LCD_DISPLAY_MODE4BIT 0x28
#define LCD_DISPLAY_POS 0x80
#define LCD_SHIFT_LEFT 0x18
#define LCD_SHIFT_RIGHT 0x1c

+static void lcd_put_byte(u8 *addr, u8 data)
+{
+#ifdef CONFIG_XTFPGA_LCD_8BIT_ACCESS
+ ACCESS_ONCE(*addr) = data;
+#else
+ ACCESS_ONCE(*addr) = data & 0xf0;
+ ACCESS_ONCE(*addr) = (data << 4) & 0xf0;
+#endif
+}
+
static int __init lcd_init(void)
{
- *LCD_INSTR_ADDR = LCD_DISPLAY_MODE8BIT;
+ ACCESS_ONCE(*LCD_INSTR_ADDR) = LCD_DISPLAY_MODE8BIT;
mdelay(5);
- *LCD_INSTR_ADDR = LCD_DISPLAY_MODE8BIT;
+ ACCESS_ONCE(*LCD_INSTR_ADDR) = LCD_DISPLAY_MODE8BIT;
udelay(200);
- *LCD_INSTR_ADDR = LCD_DISPLAY_MODE8BIT;
+ ACCESS_ONCE(*LCD_INSTR_ADDR) = LCD_DISPLAY_MODE8BIT;
+ udelay(50);
+#ifndef CONFIG_XTFPGA_LCD_8BIT_ACCESS
+ ACCESS_ONCE(*LCD_INSTR_ADDR) = LCD_DISPLAY_MODE4BIT;
+ udelay(50);
+ lcd_put_byte(LCD_INSTR_ADDR, LCD_DISPLAY_MODE4BIT);
udelay(50);
- *LCD_INSTR_ADDR = LCD_DISPLAY_ON;
+#endif
+ lcd_put_byte(LCD_INSTR_ADDR, LCD_DISPLAY_ON);
udelay(50);
- *LCD_INSTR_ADDR = LCD_CLEAR;
+ lcd_put_byte(LCD_INSTR_ADDR, LCD_CLEAR);
mdelay(10);
lcd_disp_at_pos("XTENSA LINUX", 0);
return 0;
@@ -52,10 +65,10 @@ static int __init lcd_init(void)

void lcd_disp_at_pos(char *str, unsigned char pos)
{
- *LCD_INSTR_ADDR = LCD_DISPLAY_POS | pos;
+ lcd_put_byte(LCD_INSTR_ADDR, LCD_DISPLAY_POS | pos);
udelay(100);
while (*str != 0) {
- *LCD_DATA_ADDR = *str;
+ lcd_put_byte(LCD_DATA_ADDR, *str);
udelay(200);
str++;
}
@@ -63,13 +76,13 @@ void lcd_disp_at_pos(char *str, unsigned char pos)

void lcd_shiftleft(void)
{
- *LCD_INSTR_ADDR = LCD_SHIFT_LEFT;
+ lcd_put_byte(LCD_INSTR_ADDR, LCD_SHIFT_LEFT);
udelay(50);
}

void lcd_shiftright(void)
{
- *LCD_INSTR_ADDR = LCD_SHIFT_RIGHT;
+ lcd_put_byte(LCD_INSTR_ADDR, LCD_SHIFT_RIGHT);
udelay(50);
}

--
2.3.7

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