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openwrt-owl/target/linux/s3c24xx/patches-2.6.30/013-fiq_c_handler.patch

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--- a/arch/arm/kernel/fiq.c
+++ b/arch/arm/kernel/fiq.c
@@ -8,6 +8,8 @@
*
* FIQ support re-written by Russell King to be more generic
*
+ * FIQ handler in C supoprt written by Andy Green <andy@openmoko.com>
+ *
* We now properly support a method by which the FIQ handlers can
* be stacked onto the vector. We still do not support sharing
* the FIQ vector itself.
@@ -124,6 +126,83 @@ void __naked get_fiq_regs(struct pt_regs
: "r" (&regs->ARM_r8), "I" (PSR_I_BIT | PSR_F_BIT | FIQ_MODE));
}
+/* -------- FIQ handler in C ---------
+ *
+ * Major Caveats for using this
+ * ---------------------------
+ * *
+ * * 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.
+ */
+
+static void (*current_fiq_c_isr)(void);
+#define FIQ_C_ISR_STACK_SIZE 256
+
+static void __attribute__((naked)) __jump_to_isr(void)
+{
+ asm __volatile__ ("mov pc, r8");
+}
+
+
+static void __attribute__((naked)) __actual_isr(void)
+{
+ asm __volatile__ (
+ "stmdb sp!, {r0-r12, lr};"
+ "mov fp, sp;"
+ );
+
+ current_fiq_c_isr();
+
+ asm __volatile__ (
+ "ldmia sp!, {r0-r12, lr};"
+ "subs pc, lr, #4;"
+ );
+}
+
+void set_fiq_c_handler(void (*isr)(void))
+{
+ struct pt_regs regs;
+
+ memset(&regs, 0, sizeof(regs));
+ regs.ARM_r8 = (unsigned long) __actual_isr;
+ regs.ARM_sp = 0xffff001c + FIQ_C_ISR_STACK_SIZE;
+
+ set_fiq_handler(__jump_to_isr, 4);
+
+ current_fiq_c_isr = isr;
+
+ set_fiq_regs(&regs);
+}
+/* -------- FIQ handler in C ---------*/
+
int claim_fiq(struct fiq_handler *f)
{
int ret = 0;
--- a/arch/arm/include/asm/fiq.h
+++ b/arch/arm/include/asm/fiq.h
@@ -29,8 +29,9 @@ struct fiq_handler {
extern int claim_fiq(struct fiq_handler *f);
extern void release_fiq(struct fiq_handler *f);
extern void set_fiq_handler(void *start, unsigned int length);
-extern void set_fiq_regs(struct pt_regs *regs);
-extern void get_fiq_regs(struct pt_regs *regs);
+extern void set_fiq_c_handler(void (*handler)(void));
+extern void __attribute__((naked)) set_fiq_regs(struct pt_regs *regs);
+extern void __attribute__((naked)) get_fiq_regs(struct pt_regs *regs);
extern void enable_fiq(int fiq);
extern void disable_fiq(int fiq);
--- a/arch/arm/plat-s3c24xx/include/plat/irq.h
+++ b/arch/arm/plat-s3c24xx/include/plat/irq.h
@@ -12,6 +12,7 @@
#include <linux/io.h>
+#include <mach/irqs.h>
#include <mach/hardware.h>
#include <mach/regs-irq.h>
#include <mach/regs-gpio.h>
@@ -31,8 +32,15 @@ s3c_irqsub_mask(unsigned int irqno, unsi
{
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));
@@ -45,6 +53,9 @@ s3c_irqsub_mask(unsigned int irqno, unsi
/* write back masks */
__raw_writel(submask, S3C2410_INTSUBMSK);
+#ifdef CONFIG_S3C2440_C_FIQ
+ local_irq_restore(flags);
+#endif
}
@@ -53,8 +64,15 @@ s3c_irqsub_unmask(unsigned int irqno, un
{
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));
@@ -63,6 +81,9 @@ s3c_irqsub_unmask(unsigned int irqno, un
/* write back masks */
__raw_writel(submask, S3C2410_INTSUBMSK);
__raw_writel(mask, S3C2410_INTMSK);
+#ifdef CONFIG_S3C2440_C_FIQ
+ local_irq_restore(flags);
+#endif
}
--- a/arch/arm/plat-s3c24xx/irq.c
+++ b/arch/arm/plat-s3c24xx/irq.c
@@ -28,6 +28,8 @@
#include <asm/mach/irq.h>
#include <plat/regs-irqtype.h>
+#include <mach/regs-irq.h>
+#include <mach/regs-gpio.h>
#include <plat/cpu.h>
#include <plat/pm.h>
@@ -37,12 +39,20 @@ 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
@@ -59,9 +69,19 @@ 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);
@@ -72,15 +92,25 @@ 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 = {
@@ -523,26 +553,26 @@ void __init s3c24xx_init_irq(void)
last = 0;
for (i = 0; i < 4; i++) {
- pend = __raw_readl(S3C2410_INTPND);
+ pend = __raw_readl(S3C2410_SUBSRCPND);
if (pend == 0 || pend == last)
break;
- __raw_writel(pend, S3C2410_SRCPND);
- __raw_writel(pend, S3C2410_INTPND);
- printk("irq: clearing pending status %08x\n", (int)pend);
+ printk("irq: clearing subpending status %08x\n", (int)pend);
+ __raw_writel(pend, S3C2410_SUBSRCPND);
last = pend;
}
last = 0;
for (i = 0; i < 4; i++) {
- pend = __raw_readl(S3C2410_SUBSRCPND);
+ pend = __raw_readl(S3C2410_INTPND);
if (pend == 0 || pend == last)
break;
- printk("irq: clearing subpending status %08x\n", (int)pend);
- __raw_writel(pend, S3C2410_SUBSRCPND);
+ __raw_writel(pend, S3C2410_SRCPND);
+ __raw_writel(pend, S3C2410_INTPND);
+ printk("irq: clearing pending status %08x\n", (int)pend);
last = pend;
}
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