From: zero@colonel-panic.org (Peter Horton)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] Fix AT91SAM9G20 reset
Date: Tue, 13 Apr 2010 09:31:50 +0100 [thread overview]
Message-ID: <20100413083150.GA6620@turtle.localnet> (raw)
Fix AT91SAM9G20 reset as per the errata in the data sheet.
If the SDRAM is not cleanly shutdown before reset it can be left driving
the bus, which then stops the bootloader booting from NAND.
Signed-off-by: Peter Horton <phorton@bitbox.co.uk>
--
Index: linux-2.6.32/arch/arm/mach-at91/Makefile
===================================================================
--- linux-2.6.32.orig/arch/arm/mach-at91/Makefile 2009-12-15 09:53:27.000000000 +0000
+++ linux-2.6.32/arch/arm/mach-at91/Makefile 2009-12-15 09:53:27.000000000 +0000
@@ -16,7 +16,7 @@
obj-$(CONFIG_ARCH_AT91SAM9G10) += at91sam9261.o at91sam926x_time.o at91sam9261_devices.o sam9_smc.o
obj-$(CONFIG_ARCH_AT91SAM9263) += at91sam9263.o at91sam926x_time.o at91sam9263_devices.o sam9_smc.o
obj-$(CONFIG_ARCH_AT91SAM9RL) += at91sam9rl.o at91sam926x_time.o at91sam9rl_devices.o sam9_smc.o
-obj-$(CONFIG_ARCH_AT91SAM9G20) += at91sam9260.o at91sam926x_time.o at91sam9260_devices.o sam9_smc.o
+obj-$(CONFIG_ARCH_AT91SAM9G20) += at91sam9260.o at91sam926x_time.o at91sam9260_devices.o sam9_smc.o at91sam9g20_reset.o
obj-$(CONFIG_ARCH_AT91SAM9G45) += at91sam9g45.o at91sam926x_time.o at91sam9g45_devices.o sam9_smc.o
obj-$(CONFIG_ARCH_AT91CAP9) += at91cap9.o at91sam926x_time.o at91cap9_devices.o sam9_smc.o
obj-$(CONFIG_ARCH_AT91X40) += at91x40.o at91x40_time.o
Index: linux-2.6.32/arch/arm/mach-at91/at91sam9260.c
===================================================================
--- linux-2.6.32.orig/arch/arm/mach-at91/at91sam9260.c 2009-12-03 03:51:21.000000000 +0000
+++ linux-2.6.32/arch/arm/mach-at91/at91sam9260.c 2009-12-15 09:53:27.000000000 +0000
@@ -25,6 +25,8 @@
#include "generic.h"
#include "clock.h"
+extern void at91sam9g20_reset(void);
+
static struct map_desc at91sam9260_io_desc[] __initdata = {
{
.virtual = AT91_VA_BASE_SYS,
@@ -327,7 +329,11 @@
else
iotable_init(at91sam9260_sram_desc, ARRAY_SIZE(at91sam9260_sram_desc));
- at91_arch_reset = at91sam9260_reset;
+ if (cpu_is_at91sam9g20())
+ at91_arch_reset = at91sam9g20_reset;
+ else
+ at91_arch_reset = at91sam9260_reset;
+
pm_power_off = at91sam9260_poweroff;
at91_extern_irq = (1 << AT91SAM9260_ID_IRQ0) | (1 << AT91SAM9260_ID_IRQ1)
| (1 << AT91SAM9260_ID_IRQ2);
Index: linux-2.6.32/arch/arm/mach-at91/at91sam9g20_reset.S
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6.32/arch/arm/mach-at91/at91sam9g20_reset.S 2009-12-15 09:55:17.000000000 +0000
@@ -0,0 +1,50 @@
+/*
+ * (C) BitBox Ltd 2009
+ *
+ * reset AT91SAM9G20 as per errata
+ *
+ * unless the SDRAM is cleanly shutdown before we hit the
+ * reset register it can be left driving the data bus and
+ * killing the chance of a subsequent boot from NAND
+ */
+
+#define CP15_CR_I (1 << 12)
+
+#define SYS_VIRT_OFS (-0x01000000)
+
+#define SDRAMC_BASE (SYS_VIRT_OFS + 0xffffea00)
+#define SDRAMC_TR 0x0004
+#define SDRAMC_LPR 0x0010
+#define SDRAMC_LPCB_POWER_DOWN 2
+
+#define RSTC_BASE (SYS_VIRT_OFS + 0xfffffd00)
+#define RSTC_CR 0x0000
+#define RSTC_PROCRST (1 << 0)
+#define RSTC_PERRST (1 << 2)
+#define RSTC_KEY (0xa5 << 24)
+
+ .arm
+
+ .globl at91sam9g20_reset
+
+at91sam9g20_reset: mov r0, #0
+ mcr p15, 0, r0, c7, c5, 0 @ flush I-cache
+
+ mrc p15, 0, r0, c1, c0, 0
+ orr r0, r0, #CP15_CR_I
+ mcr p15, 0, r0, c1, c0, 0 @ enable I-cache
+
+ ldr r0, =SDRAMC_BASE @ preload constants
+ ldr r1, =RSTC_BASE
+
+ mov r2, #1
+ mov r3, #SDRAMC_LPCB_POWER_DOWN
+ ldr r4, =RSTC_KEY | RSTC_PERRST | RSTC_PROCRST
+
+ .balign 32 @ align to cache line
+
+ str r2, [r0, #SDRAMC_TR] @ disable SDRAM access
+ str r3, [r0, #SDRAMC_LPR] @ power down SDRAM
+ str r4, [r1, #RSTC_CR] @ reset processor
+
+ b .
next reply other threads:[~2010-04-13 8:31 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-04-13 8:31 Peter Horton [this message]
-- strict thread matches above, loose matches on Subject: below --
2010-05-28 15:37 [PATCH] Fix AT91SAM9G20 reset Peter Horton
2010-06-21 14:30 ` Lucas
2010-06-21 15:14 ` Peter Horton
2010-10-14 13:34 ` Nicolas Ferre
2010-10-14 15:31 ` Peter Horton
2009-12-15 9:59 Peter Horton
2009-12-09 13:50 Peter Horton
2009-12-09 14:09 ` Paulius Zaleckas
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