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From 6a2c7de90f47b7eb74f3cb2d181f950ece22b3fb Mon Sep 17 00:00:00 2001
From: mokopatches <mokopatches@openmoko.org>
Date: Fri, 25 Jul 2008 22:21:22 +0100
Subject: [PATCH] introduce-fiq-basis.patch
Adds a C-based FIQ ISR which is very convenient (and unusual --
normally you have to do FIQ ISR in assembler only).
Based on my article:
http://warmcat.com/_wp/2007/09/17/at91rm9200-fiq-faq-and-simple-example-code-patch/
Implemented as a platform device and driver.
Suspend / resume is tested and works.
Signed-off-by: Andy Green <andy@warmcat.com>
---
arch/arm/mach-s3c2440/Kconfig | 7 +
arch/arm/mach-s3c2440/Makefile | 1 +
arch/arm/mach-s3c2440/fiq_c_isr.c | 250 ++++++++++++++++++++++++++
arch/arm/mach-s3c2440/fiq_c_isr.h | 64 +++++++
arch/arm/mach-s3c2440/mach-gta02.c | 22 +++
arch/arm/plat-s3c24xx/irq.c | 32 +++-
include/asm-arm/arch-s3c2410/fiq_ipc_gta02.h | 28 +++
include/asm-arm/plat-s3c24xx/irq.h | 20 ++
8 files changed, 422 insertions(+), 2 deletions(-)
create mode 100644 arch/arm/mach-s3c2440/fiq_c_isr.c
create mode 100644 arch/arm/mach-s3c2440/fiq_c_isr.h
create mode 100644 include/asm-arm/arch-s3c2410/fiq_ipc_gta02.h
diff --git a/arch/arm/mach-s3c2440/Kconfig b/arch/arm/mach-s3c2440/Kconfig
index 6b317d1..3015aaf 100644
--- a/arch/arm/mach-s3c2440/Kconfig
+++ b/arch/arm/mach-s3c2440/Kconfig
@@ -22,6 +22,13 @@ config S3C2440_DMA
help
Support for S3C2440 specific DMA code5A
+config S3C2440_C_FIQ
+ bool "FIQ ISR support in C"
+ depends on ARCH_S3C2410
+ select FIQ
+ help
+ Support for S3C2440 FIQ support in C -- see
+ ./arch/arm/macs3c2440/fiq_c_isr.c
menu "S3C2440 Machines"
diff --git a/arch/arm/mach-s3c2440/Makefile b/arch/arm/mach-s3c2440/Makefile
index 1a4defd..4932232 100644
--- a/arch/arm/mach-s3c2440/Makefile
+++ b/arch/arm/mach-s3c2440/Makefile
@@ -13,6 +13,7 @@ obj-$(CONFIG_CPU_S3C2440) += s3c2440.o dsc.o
obj-$(CONFIG_CPU_S3C2440) += irq.o
obj-$(CONFIG_CPU_S3C2440) += clock.o
obj-$(CONFIG_S3C2440_DMA) += dma.o
+obj-$(CONFIG_S3C2440_C_FIQ) += fiq_c_isr.o
# Machine support
diff --git a/arch/arm/mach-s3c2440/fiq_c_isr.c b/arch/arm/mach-s3c2440/fiq_c_isr.c
new file mode 100644
index 0000000..12f4527
--- /dev/null
+++ b/arch/arm/mach-s3c2440/fiq_c_isr.c
@@ -0,0 +1,250 @@
+/*
+ * Copyright 2007 Andy Green <andy@warmcat.com>
+ * S3C modfifications
+ * Copyright 2008 Andy Green <andy@openmoko.com>
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <asm/hardware.h>
+#include <asm/fiq.h>
+#include "fiq_c_isr.h"
+#include <linux/sysfs.h>
+#include <linux/device.h>
+#include <linux/platform_device.h>
+
+#include <asm/io.h>
+
+#include <asm/plat-s3c24xx/cpu.h>
+#include <asm/plat-s3c24xx/irq.h>
+
+/*
+ * Major Caveats for using FIQ
+ * ---------------------------
+ *
+ * 1) it CANNOT touch any vmalloc()'d memory, only memory
+ * that was kmalloc()'d. Static allocations in the monolithic kernel
+ * are kmalloc()'d so they are okay. You can touch memory-mapped IO, but
+ * the pointer for it has to have been stored in kmalloc'd memory. The
+ * reason for this is simple: every now and then Linux turns off interrupts
+ * and reorders the paging tables. If a FIQ happens during this time, the
+ * virtual memory space can be partly or entirely disordered or missing.
+ *
+ * 2) Because vmalloc() is used when a module is inserted, THIS FIQ
+ * ISR HAS TO BE IN THE MONOLITHIC KERNEL, not a module. But the way
+ * it is set up, you can all to enable and disable it from your module
+ * and intercommunicate with it through struct fiq_ipc
+ * fiq_ipc which you can define in
+ * asm/archfiq_ipc_type.h. The reason is the same as above, a
+ * FIQ could happen while even the ISR is not present in virtual memory
+ * space due to pagetables being changed at the time.
+ *
+ * 3) You can't call any Linux API code except simple macros
+ * - understand that FIQ can come in at any time, no matter what
+ * state of undress the kernel may privately be in, thinking it
+ * locked the door by turning off interrupts... FIQ is an
+ * unstoppable monster force (which is its value)
+ * - they are not vmalloc()'d memory safe
+ * - they might do crazy stuff like sleep: FIQ pisses fire and
+ * is not interested in 'sleep' that the weak seem to need
+ * - calling APIs from FIQ can re-enter un-renterable things
+ * - summary: you cannot interoperate with linux APIs directly in the FIQ ISR
+ *
+ * If you follow these rules, it is fantastic, an extremely powerful, solid,
+ * genuine hard realtime feature.
+ *
+ */
+
+/* more than enough to cover our jump instruction to the isr */
+#define SIZEOF_FIQ_JUMP 8
+/* more than enough to cover s3c2440_fiq_isr() in 4K blocks */
+#define SIZEOF_FIQ_ISR 0x2000
+/* increase the size of the stack that is active during FIQ as needed */
+static u8 u8aFiqStack[4096];
+
+/* only one FIQ ISR possible, okay to do these here */
+u32 _fiq_ack_mask; /* used by isr exit define */
+unsigned long _fiq_count_fiqs; /* used by isr exit define */
+static int _fiq_irq; /* private ; irq index we were started with, or 0 */
+
+/* this function must live in the monolithic kernel somewhere! A module is
+ * NOT good enough!
+ */
+extern void __attribute__ ((naked)) s3c2440_fiq_isr(void);
+
+/* this is copied into the hard FIQ vector during init */
+
+static void __attribute__ ((naked)) s3c2440_FIQ_Branch(void)
+{
+ asm __volatile__ (
+ "mov pc, r8 ; "
+ );
+}
+
+/* sysfs */
+
+static ssize_t show_count(struct device *dev, struct device_attribute *attr,
+ char *buf)
+{
+ return sprintf(buf, "%ld\n", _fiq_count_fiqs);
+}
+
+static DEVICE_ATTR(count, 0444, show_count, NULL);
+
+static struct attribute *s3c2440_fiq_sysfs_entries[] = {
+ &dev_attr_count.attr,
+ NULL
+};
+
+static struct attribute_group s3c2440_fiq_attr_group = {
+ .name = "fiq",
+ .attrs = s3c2440_fiq_sysfs_entries,
+};
+
+/*
+ * call this from your kernel module to set up the FIQ ISR to service FIQs,
+ * You need to have configured your FIQ input pin before anything will happen
+ *
+ * call it with, eg, IRQ_TIMER3 from asm-arm/arch-s3c2410/irqs.h
+ *
+ * you still need to clear the source interrupt in S3C2410_INTMSK to get
+ * anything good happening
+ */
+static void fiq_init_irq_source(int irq_index_fiq)
+{
+ if (!irq_index_fiq) /* no interrupt */
+ return;
+
+ printk(KERN_INFO"Enabling FIQ using int idx %d\n",
+ irq_index_fiq - S3C2410_CPUIRQ_OFFSET);
+ local_fiq_disable();
+
+ _fiq_irq = irq_index_fiq;
+ _fiq_ack_mask = 1 << (irq_index_fiq - S3C2410_CPUIRQ_OFFSET);
+
+ /* let our selected interrupt be a magic FIQ interrupt */
+ __raw_writel(_fiq_ack_mask, S3C2410_INTMOD);
+
+ /* it's ready to go as soon as we unmask the source in S3C2410_INTMSK */
+ local_fiq_enable();
+}
+
+
+/* call this from your kernel module to disable generation of FIQ actions */
+static void fiq_disable_irq_source(void)
+{
+ /* nothing makes FIQ any more */
+ __raw_writel(0, S3C2410_INTMOD);
+ local_fiq_disable();
+ _fiq_irq = 0; /* no active source interrupt now either */
+}
+
+/* this starts FIQ timer events... they continue until the FIQ ISR sees that
+ * its work is done and it turns off the timer. After setting up the fiq_ipc
+ * struct with new work, you call this to start FIQ timer actions up again.
+ * Only the FIQ ISR decides when it is done and controls turning off the
+ * timer events.
+ */
+void fiq_kick(void)
+{
+ unsigned long flags;
+
+ /* we have to take care about FIQ because this modification is
+ * non-atomic, FIQ could come in after the read and before the
+ * writeback and its changes to the register would be lost
+ * (platform INTMSK mod code is taken care of already)
+ */
+ local_save_flags(flags);
+ local_fiq_disable();
+ __raw_writel(__raw_readl(S3C2410_INTMSK) &
+ ~(1 << (_fiq_irq - S3C2410_CPUIRQ_OFFSET)),
+ S3C2410_INTMSK);
+ local_irq_restore(flags);
+}
+EXPORT_SYMBOL_GPL(fiq_kick);
+
+
+
+static int __init sc32440_fiq_probe(struct platform_device *pdev)
+{
+ struct resource *r = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
+
+ if (!r)
+ return -EIO;
+ /* configure for the interrupt we are meant to use */
+ fiq_init_irq_source(r->start);
+
+ return sysfs_create_group(&pdev->dev.kobj, &s3c2440_fiq_attr_group);
+}
+
+static int sc32440_fiq_remove(struct platform_device *pdev)
+{
+ fiq_disable_irq_source();
+ sysfs_remove_group(&pdev->dev.kobj, &s3c2440_fiq_attr_group);
+ return 0;
+}
+
+static void fiq_set_vector_and_regs(void)
+{
+ struct pt_regs regs;
+
+ /* prep the special FIQ mode regs */
+ memset(&regs, 0, sizeof(regs));
+ regs.ARM_r8 = (unsigned long)s3c2440_fiq_isr;
+ regs.ARM_sp = (unsigned long)u8aFiqStack + sizeof(u8aFiqStack) - 4;
+ /* set up the special FIQ-mode-only registers from our regs */
+ set_fiq_regs(&regs);
+ /* copy our jump to the real ISR into the hard vector address */
+ set_fiq_handler(s3c2440_FIQ_Branch, SIZEOF_FIQ_JUMP);
+}
+
+#ifdef CONFIG_PM
+static int sc32440_fiq_suspend(struct platform_device *pdev, pm_message_t state)
+{
+ /* nothing makes FIQ any more */
+ __raw_writel(0, S3C2410_INTMOD);
+ local_fiq_disable();
+
+ return 0;
+}
+
+static int sc32440_fiq_resume(struct platform_device *pdev)
+{
+ fiq_set_vector_and_regs();
+ fiq_init_irq_source(_fiq_irq);
+ return 0;
+}
+#else
+#define sc32440_fiq_suspend NULL
+#define sc32440_fiq_resume NULL
+#endif
+
+static struct platform_driver sc32440_fiq_driver = {
+ .driver = {
+ .name = "sc32440_fiq",
+ .owner = THIS_MODULE,
+ },
+
+ .probe = sc32440_fiq_probe,
+ .remove = __devexit_p(sc32440_fiq_remove),
+ .suspend = sc32440_fiq_suspend,
+ .resume = sc32440_fiq_resume,
+};
+
+static int __init sc32440_fiq_init(void)
+{
+ fiq_set_vector_and_regs();
+
+ return platform_driver_register(&sc32440_fiq_driver);
+}
+
+static void __exit sc32440_fiq_exit(void)
+{
+ fiq_disable_irq_source();
+}
+
+MODULE_AUTHOR("Andy Green <andy@openmoko.com>");
+MODULE_LICENSE("GPL");
+
+module_init(sc32440_fiq_init);
+module_exit(sc32440_fiq_exit);
diff --git a/arch/arm/mach-s3c2440/fiq_c_isr.h b/arch/arm/mach-s3c2440/fiq_c_isr.h
new file mode 100644
index 0000000..f08740e
--- /dev/null
+++ b/arch/arm/mach-s3c2440/fiq_c_isr.h
@@ -0,0 +1,64 @@
+#ifndef _LINUX_FIQ_C_ISR_H
+#define _LINUX_FIQ_C_ISR_H
+
+#include <asm/arch-s3c2410/regs-irq.h>
+
+extern unsigned long _fiq_count_fiqs;
+extern u32 _fiq_ack_mask;
+
+/* This CANNOT be implemented in a module -- it has to be used in code
+ * included in the monolithic kernel
+ */
+
+#define FIQ_HANDLER_START() \
+void __attribute__ ((naked)) s3c2440_fiq_isr(void) \
+{\
+ /*\
+ * you can declare local vars here, take care to set the frame size\
+ * below accordingly if there are more than a few dozen bytes of them\
+ */\
+
+/* stick your locals here :-)
+ * Do NOT initialize them here! define them and initialize them after
+ * FIQ_HANDLER_ENTRY() is done.
+ */
+
+#define FIQ_HANDLER_ENTRY(LOCALS, FRAME) \
+ const int _FIQ_FRAME_SIZE = FRAME; \
+ /* entry takes care to store registers we will be treading on here */\
+ asm __volatile__ (\
+ "mov ip, sp ;"\
+ /* stash FIQ and r0-r8 normal regs */\
+ "stmdb sp!, {r0-r12, lr};"\
+ /* allow SP to get some space */\
+ "sub sp, sp, %1 ;"\
+ /* !! THIS SETS THE FRAME, adjust to > sizeof locals */\
+ "sub fp, sp, %0 ;"\
+ :\
+ : "rI" (LOCALS), "rI" (FRAME)\
+ :"r9"\
+ );
+
+/* stick your ISR code here and then end with... */
+
+#define FIQ_HANDLER_END() \
+ _fiq_count_fiqs++;\
+ __raw_writel(_fiq_ack_mask, S3C2410_SRCPND);\
+\
+ /* exit back to normal mode restoring everything */\
+ asm __volatile__ (\
+ /* pop our allocation */\
+ "add sp, sp, %0 ;"\
+ /* return FIQ regs back to pristine state\
+ * and get normal regs back\
+ */\
+ "ldmia sp!, {r0-r12, lr};"\
+\
+ /* return */\
+ "subs pc, lr, #4;"\
+ : \
+ : "rI" (_FIQ_FRAME_SIZE) \
+ );\
+}
+
+#endif /* _LINUX_FIQ_C_ISR_H */
diff --git a/arch/arm/mach-s3c2440/mach-gta02.c b/arch/arm/mach-s3c2440/mach-gta02.c
index 46acede..0bdd0e0 100644
--- a/arch/arm/mach-s3c2440/mach-gta02.c
+++ b/arch/arm/mach-s3c2440/mach-gta02.c
@@ -78,9 +78,31 @@
#include <linux/glamofb.h>
+#include <asm/arch/fiq_ipc_gta02.h>
+#include "fiq_c_isr.h"
+
/* arbitrates which sensor IRQ owns the shared SPI bus */
static spinlock_t motion_irq_lock;
+/* define FIQ IPC struct */
+/*
+ * contains stuff FIQ ISR modifies and normal kernel code can see and use
+ * this is defined in <asm/arch/fiq_ipc_gta02.h>, you should customize
+ * the definition in there and include the same definition in your kernel
+ * module that wants to interoperate with your FIQ code.
+ */
+struct fiq_ipc fiq_ipc;
+EXPORT_SYMBOL(fiq_ipc);
+
+/* define FIQ ISR */
+
+FIQ_HANDLER_START()
+/* define your locals here -- no initializers though */
+FIQ_HANDLER_ENTRY(256, 512)
+/* Your ISR here :-) */
+FIQ_HANDLER_END()
+
+
static struct map_desc gta02_iodesc[] __initdata = {
{
.virtual = 0xe0000000,
diff --git a/arch/arm/plat-s3c24xx/irq.c b/arch/arm/plat-s3c24xx/irq.c
index ae2c5d7..9887db1 100644
--- a/arch/arm/plat-s3c24xx/irq.c
+++ b/arch/arm/plat-s3c24xx/irq.c
@@ -133,12 +133,20 @@ static void
s3c_irq_mask(unsigned int irqno)
{
unsigned long mask;
-
+#ifdef CONFIG_S3C2440_C_FIQ
+ unsigned long flags;
+#endif
irqno -= IRQ_EINT0;
-
+#ifdef CONFIG_S3C2440_C_FIQ
+ local_save_flags(flags);
+ local_fiq_disable();
+#endif
mask = __raw_readl(S3C2410_INTMSK);
mask |= 1UL << irqno;
__raw_writel(mask, S3C2410_INTMSK);
+#ifdef CONFIG_S3C2440_C_FIQ
+ local_irq_restore(flags);
+#endif
}
static inline void
@@ -155,9 +163,19 @@ s3c_irq_maskack(unsigned int irqno)
{
unsigned long bitval = 1UL << (irqno - IRQ_EINT0);
unsigned long mask;
+#ifdef CONFIG_S3C2440_C_FIQ
+ unsigned long flags;
+#endif
+#ifdef CONFIG_S3C2440_C_FIQ
+ local_save_flags(flags);
+ local_fiq_disable();
+#endif
mask = __raw_readl(S3C2410_INTMSK);
__raw_writel(mask|bitval, S3C2410_INTMSK);
+#ifdef CONFIG_S3C2440_C_FIQ
+ local_irq_restore(flags);
+#endif
__raw_writel(bitval, S3C2410_SRCPND);
__raw_writel(bitval, S3C2410_INTPND);
@@ -168,15 +186,25 @@ static void
s3c_irq_unmask(unsigned int irqno)
{
unsigned long mask;
+#ifdef CONFIG_S3C2440_C_FIQ
+ unsigned long flags;
+#endif
if (irqno != IRQ_TIMER4 && irqno != IRQ_EINT8t23)
irqdbf2("s3c_irq_unmask %d\n", irqno);
irqno -= IRQ_EINT0;
+#ifdef CONFIG_S3C2440_C_FIQ
+ local_save_flags(flags);
+ local_fiq_disable();
+#endif
mask = __raw_readl(S3C2410_INTMSK);
mask &= ~(1UL << irqno);
__raw_writel(mask, S3C2410_INTMSK);
+#ifdef CONFIG_S3C2440_C_FIQ
+ local_irq_restore(flags);
+#endif
}
struct irq_chip s3c_irq_level_chip = {
diff --git a/include/asm-arm/arch-s3c2410/fiq_ipc_gta02.h b/include/asm-arm/arch-s3c2410/fiq_ipc_gta02.h
new file mode 100644
index 0000000..341f2bb
--- /dev/null
+++ b/include/asm-arm/arch-s3c2410/fiq_ipc_gta02.h
@@ -0,0 +1,28 @@
+#ifndef _LINUX_FIQ_IPC_H
+#define _LINUX_FIQ_IPC_H
+
+/*
+ * this defines the struct which is used to communicate between the FIQ
+ * world and the normal linux kernel world. One of these structs is
+ * statically defined for you in the monolithic kernel so the FIQ ISR code
+ * can safely touch it any any time.
+ *
+ * You also want to include this file in your kernel module that wants to
+ * communicate with your FIQ code. Add any kinds of vars that are used by
+ * the FIQ ISR and the module in here.
+ *
+ * To get you started there is just an int that is incremented every FIQ
+ * you can remove this when you are ready to customize, but it is useful
+ * for testing
+ */
+
+struct fiq_ipc {
+ u8 u8a[0]; /* placeholder */
+};
+
+/* actual definition lives in arch/arm/mach-s3c2440/fiq_c_isr.c */
+extern struct fiq_ipc fiq_ipc;
+
+extern void fiq_kick(void); /* provoke a FIQ "immediately" */
+
+#endif /* _LINUX_FIQ_IPC_H */
diff --git a/include/asm-arm/plat-s3c24xx/irq.h b/include/asm-arm/plat-s3c24xx/irq.h
index 45746a9..bf15e1c 100644
--- a/include/asm-arm/plat-s3c24xx/irq.h
+++ b/include/asm-arm/plat-s3c24xx/irq.h
@@ -25,8 +25,15 @@ s3c_irqsub_mask(unsigned int irqno, unsigned int parentbit,
{
unsigned long mask;
unsigned long submask;
+#ifdef CONFIG_S3C2440_C_FIQ
+ unsigned long flags;
+#endif
submask = __raw_readl(S3C2410_INTSUBMSK);
+#ifdef CONFIG_S3C2440_C_FIQ
+ local_save_flags(flags);
+ local_fiq_disable();
+#endif
mask = __raw_readl(S3C2410_INTMSK);
submask |= (1UL << (irqno - IRQ_S3CUART_RX0));
@@ -39,6 +46,9 @@ s3c_irqsub_mask(unsigned int irqno, unsigned int parentbit,
/* write back masks */
__raw_writel(submask, S3C2410_INTSUBMSK);
+#ifdef CONFIG_S3C2440_C_FIQ
+ local_irq_restore(flags);
+#endif
}
@@ -47,8 +57,15 @@ s3c_irqsub_unmask(unsigned int irqno, unsigned int parentbit)
{
unsigned long mask;
unsigned long submask;
+#ifdef CONFIG_S3C2440_C_FIQ
+ unsigned long flags;
+#endif
submask = __raw_readl(S3C2410_INTSUBMSK);
+#ifdef CONFIG_S3C2440_C_FIQ
+ local_save_flags(flags);
+ local_fiq_disable();
+#endif
mask = __raw_readl(S3C2410_INTMSK);
submask &= ~(1UL << (irqno - IRQ_S3CUART_RX0));
@@ -57,6 +74,9 @@ s3c_irqsub_unmask(unsigned int irqno, unsigned int parentbit)
/* write back masks */
__raw_writel(submask, S3C2410_INTSUBMSK);
__raw_writel(mask, S3C2410_INTMSK);
+#ifdef CONFIG_S3C2440_C_FIQ
+ local_irq_restore(flags);
+#endif
}
--
1.5.6.3
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