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

   1 Index: linux-2.6.30-rc6/arch/arm/kernel/fiq.c
   2 ===================================================================
   3 --- linux-2.6.30-rc6.orig/arch/arm/kernel/fiq.c 2009-05-16 06:12:57.000000000 +0200
   4 +++ linux-2.6.30-rc6/arch/arm/kernel/fiq.c      2009-05-18 19:08:30.000000000 +0200
   5 @@ -8,6 +8,8 @@
   6   *
   7   *  FIQ support re-written by Russell King to be more generic
   8   *
   9 + *  FIQ handler in C supoprt written by Andy Green <andy@openmoko.com>
  10 + *
  11   * We now properly support a method by which the FIQ handlers can
  12   * be stacked onto the vector.  We still do not support sharing
  13   * the FIQ vector itself.
  14 @@ -124,6 +126,83 @@
  15         : "r" (&regs->ARM_r8), "I" (PSR_I_BIT | PSR_F_BIT | FIQ_MODE));
  16  }
  17
  18 +/* -------- FIQ handler in C ---------
  19 + *
  20 + * Major Caveats for using this
  21 + *  ---------------------------
  22 + *  *
  23 + *  * 1) it CANNOT touch any vmalloc()'d memory, only memory
  24 + *    that was kmalloc()'d.  Static allocations in the monolithic kernel
  25 + *    are kmalloc()'d so they are okay.  You can touch memory-mapped IO, but
  26 + *    the pointer for it has to have been stored in kmalloc'd memory.  The
  27 + *    reason for this is simple: every now and then Linux turns off interrupts
  28 + *    and reorders the paging tables.  If a FIQ happens during this time, the
  29 + *    virtual memory space can be partly or entirely disordered or missing.
  30 + *
  31 + * 2) Because vmalloc() is used when a module is inserted, THIS FIQ
  32 + *    ISR HAS TO BE IN THE MONOLITHIC KERNEL, not a module.  But the way
  33 + *    it is set up, you can all to enable and disable it from your module
  34 + *    and intercommunicate with it through struct fiq_ipc
  35 + *    fiq_ipc which you can define in
  36 + *    asm/archfiq_ipc_type.h.  The reason is the same as above, a
  37 + *    FIQ could happen while even the ISR is not present in virtual memory
  38 + *    space due to pagetables being changed at the time.
  39 + *
  40 + * 3) You can't call any Linux API code except simple macros
  41 + *    - understand that FIQ can come in at any time, no matter what
  42 + *      state of undress the kernel may privately be in, thinking it
  43 + *      locked the door by turning off interrupts... FIQ is an
  44 + *      unstoppable monster force (which is its value)
  45 + *    - they are not vmalloc()'d memory safe
  46 + *    - they might do crazy stuff like sleep: FIQ pisses fire and
  47 + *      is not interested in 'sleep' that the weak seem to need
  48 + *    - calling APIs from FIQ can re-enter un-renterable things
  49 + *    - summary: you cannot interoperate with linux APIs directly in the FIQ ISR
  50 + *
  51 + * If you follow these rules, it is fantastic, an extremely powerful, solid,
  52 + * genuine hard realtime feature.
  53 + */
  54 +
  55 +static void (*current_fiq_c_isr)(void);
  56 +#define FIQ_C_ISR_STACK_SIZE   256
  57 +
  58 +static void __attribute__((naked)) __jump_to_isr(void)
  59 +{
  60 +       asm __volatile__ ("mov pc, r8");
  61 +}
  62 +
  63 +
  64 +static void __attribute__((naked)) __actual_isr(void)
  65 +{
  66 +       asm __volatile__ (
  67 +               "stmdb  sp!, {r0-r12, lr};"
  68 +               "mov     fp, sp;"
  69 +       );
  70 +
  71 +       current_fiq_c_isr();
  72 +
  73 +       asm __volatile__ (
  74 +               "ldmia  sp!, {r0-r12, lr};"
  75 +               "subs   pc, lr, #4;"
  76 +       );
  77 +}
  78 +
  79 +void set_fiq_c_handler(void (*isr)(void))
  80 +{
  81 +       struct pt_regs regs;
  82 +
  83 +       memset(&regs, 0, sizeof(regs));
  84 +       regs.ARM_r8 = (unsigned long) __actual_isr;
  85 +       regs.ARM_sp = 0xffff001c + FIQ_C_ISR_STACK_SIZE;
  86 +
  87 +       set_fiq_handler(__jump_to_isr, 4);
  88 +
  89 +       current_fiq_c_isr = isr;
  90 +
  91 +       set_fiq_regs(&regs);
  92 +}
  93 +/* -------- FIQ handler in C ---------*/
  94 +
  95  int claim_fiq(struct fiq_handler *f)
  96  {
  97         int ret = 0;
  98 Index: linux-2.6.30-rc6/arch/arm/include/asm/fiq.h
  99 ===================================================================
 100 --- linux-2.6.30-rc6.orig/arch/arm/include/asm/fiq.h    2009-05-16 06:12:57.000000000 +0200
 101 +++ linux-2.6.30-rc6/arch/arm/include/asm/fiq.h 2009-05-18 19:08:30.000000000 +0200
 102 @@ -29,8 +29,9 @@
 103  extern int claim_fiq(struct fiq_handler *f);
 104  extern void release_fiq(struct fiq_handler *f);
 105  extern void set_fiq_handler(void *start, unsigned int length);
 106 -extern void set_fiq_regs(struct pt_regs *regs);
 107 -extern void get_fiq_regs(struct pt_regs *regs);
 108 +extern void set_fiq_c_handler(void (*handler)(void));
 109 +extern void __attribute__((naked)) set_fiq_regs(struct pt_regs *regs);
 110 +extern void __attribute__((naked)) get_fiq_regs(struct pt_regs *regs);
 111  extern void enable_fiq(int fiq);
 112  extern void disable_fiq(int fiq);
 113
 114 Index: linux-2.6.30-rc6/arch/arm/plat-s3c24xx/include/plat/irq.h
 115 ===================================================================
 116 --- linux-2.6.30-rc6.orig/arch/arm/plat-s3c24xx/include/plat/irq.h      2009-05-16 06:12:57.000000000 +0200
 117 +++ linux-2.6.30-rc6/arch/arm/plat-s3c24xx/include/plat/irq.h   2009-05-18 19:08:30.000000000 +0200
 118 @@ -12,6 +12,7 @@
 119
 120  #include <linux/io.h>
 121
 122 +#include <mach/irqs.h>
 123  #include <mach/hardware.h>
 124  #include <mach/regs-irq.h>
 125  #include <mach/regs-gpio.h>
 126 @@ -31,8 +32,15 @@
 127  {
 128         unsigned long mask;
 129         unsigned long submask;
 130 +#ifdef CONFIG_S3C2440_C_FIQ
 131 +       unsigned long flags;
 132 +#endif
 133
 134         submask = __raw_readl(S3C2410_INTSUBMSK);
 135 +#ifdef CONFIG_S3C2440_C_FIQ
 136 +       local_save_flags(flags);
 137 +       local_fiq_disable();
 138 +#endif
 139         mask = __raw_readl(S3C2410_INTMSK);
 140
 141         submask |= (1UL << (irqno - IRQ_S3CUART_RX0));
 142 @@ -45,6 +53,9 @@
 143
 144         /* write back masks */
 145         __raw_writel(submask, S3C2410_INTSUBMSK);
 146 +#ifdef CONFIG_S3C2440_C_FIQ
 147 +       local_irq_restore(flags);
 148 +#endif
 149
 150  }
 151
 152 @@ -53,8 +64,15 @@
 153  {
 154         unsigned long mask;
 155         unsigned long submask;
 156 +#ifdef CONFIG_S3C2440_C_FIQ
 157 +       unsigned long flags;
 158 +#endif
 159
 160         submask = __raw_readl(S3C2410_INTSUBMSK);
 161 +#ifdef CONFIG_S3C2440_C_FIQ
 162 +       local_save_flags(flags);
 163 +       local_fiq_disable();
 164 +#endif
 165         mask = __raw_readl(S3C2410_INTMSK);
 166
 167         submask &= ~(1UL << (irqno - IRQ_S3CUART_RX0));
 168 @@ -63,6 +81,9 @@
 169         /* write back masks */
 170         __raw_writel(submask, S3C2410_INTSUBMSK);
 171         __raw_writel(mask, S3C2410_INTMSK);
 172 +#ifdef CONFIG_S3C2440_C_FIQ
 173 +       local_irq_restore(flags);
 174 +#endif
 175  }
 176
 177
 178 Index: linux-2.6.30-rc6/arch/arm/plat-s3c24xx/irq.c
 179 ===================================================================
 180 --- linux-2.6.30-rc6.orig/arch/arm/plat-s3c24xx/irq.c   2009-05-16 06:12:57.000000000 +0200
 181 +++ linux-2.6.30-rc6/arch/arm/plat-s3c24xx/irq.c        2009-05-18 19:08:30.000000000 +0200
 182 @@ -28,6 +28,8 @@
 183  #include <asm/mach/irq.h>
 184
 185  #include <plat/regs-irqtype.h>
 186 +#include <mach/regs-irq.h>
 187 +#include <mach/regs-gpio.h>
 188
 189  #include <plat/cpu.h>
 190  #include <plat/pm.h>
 191 @@ -37,12 +39,20 @@
 192  s3c_irq_mask(unsigned int irqno)
 193  {
 194         unsigned long mask;
 195 -
 196 +#ifdef CONFIG_S3C2440_C_FIQ
 197 +       unsigned long flags;
 198 +#endif
 199         irqno -= IRQ_EINT0;
 200 -
 201 +#ifdef CONFIG_S3C2440_C_FIQ
 202 +       local_save_flags(flags);
 203 +       local_fiq_disable();
 204 +#endif
 205         mask = __raw_readl(S3C2410_INTMSK);
 206         mask |= 1UL << irqno;
 207         __raw_writel(mask, S3C2410_INTMSK);
 208 +#ifdef CONFIG_S3C2440_C_FIQ
 209 +       local_irq_restore(flags);
 210 +#endif
 211  }
 212
 213  static inline void
 214 @@ -59,9 +69,19 @@
 215  {
 216         unsigned long bitval = 1UL << (irqno - IRQ_EINT0);
 217         unsigned long mask;
 218 -
 219 +#ifdef CONFIG_S3C2440_C_FIQ
 220 +       unsigned long flags;
 221 +#endif
 222 +
 223 +#ifdef CONFIG_S3C2440_C_FIQ
 224 +       local_save_flags(flags);
 225 +       local_fiq_disable();
 226 +#endif
 227         mask = __raw_readl(S3C2410_INTMSK);
 228         __raw_writel(mask|bitval, S3C2410_INTMSK);
 229 +#ifdef CONFIG_S3C2440_C_FIQ
 230 +       local_irq_restore(flags);
 231 +#endif
 232
 233         __raw_writel(bitval, S3C2410_SRCPND);
 234         __raw_writel(bitval, S3C2410_INTPND);
 235 @@ -72,15 +92,25 @@
 236  s3c_irq_unmask(unsigned int irqno)
 237  {
 238         unsigned long mask;
 239 +#ifdef CONFIG_S3C2440_C_FIQ
 240 +       unsigned long flags;
 241 +#endif
 242
 243         if (irqno != IRQ_TIMER4 && irqno != IRQ_EINT8t23)
 244                 irqdbf2("s3c_irq_unmask %d\n", irqno);
 245
 246         irqno -= IRQ_EINT0;
 247
 248 +#ifdef CONFIG_S3C2440_C_FIQ
 249 +       local_save_flags(flags);
 250 +       local_fiq_disable();
 251 +#endif
 252         mask = __raw_readl(S3C2410_INTMSK);
 253         mask &= ~(1UL << irqno);
 254         __raw_writel(mask, S3C2410_INTMSK);
 255 +#ifdef CONFIG_S3C2440_C_FIQ
 256 +       local_irq_restore(flags);
 257 +#endif
 258  }
 259
 260  struct irq_chip s3c_irq_level_chip = {
 261 @@ -523,26 +553,26 @@
 262
 263         last = 0;
 264         for (i = 0; i < 4; i++) {
 265 -               pend = __raw_readl(S3C2410_INTPND);
 266 +               pend = __raw_readl(S3C2410_SUBSRCPND);
 267
 268                 if (pend == 0 || pend == last)
 269                         break;
 270
 271 -               __raw_writel(pend, S3C2410_SRCPND);
 272 -               __raw_writel(pend, S3C2410_INTPND);
 273 -               printk("irq: clearing pending status %08x\n", (int)pend);
 274 +               printk("irq: clearing subpending status %08x\n", (int)pend);
 275 +               __raw_writel(pend, S3C2410_SUBSRCPND);
 276                 last = pend;
 277         }
 278
 279         last = 0;
 280         for (i = 0; i < 4; i++) {
 281 -               pend = __raw_readl(S3C2410_SUBSRCPND);
 282 +               pend = __raw_readl(S3C2410_INTPND);
 283
 284                 if (pend == 0 || pend == last)
 285                         break;
 286
 287 -               printk("irq: clearing subpending status %08x\n", (int)pend);
 288 -               __raw_writel(pend, S3C2410_SUBSRCPND);
 289 +               __raw_writel(pend, S3C2410_SRCPND);
 290 +               __raw_writel(pend, S3C2410_INTPND);
 291 +               printk("irq: clearing pending status %08x\n", (int)pend);
 292                 last = pend;
 293         }
 294