arch/arm/mach-omap1/ams-delta-fiq.c

   1 /*
   2  *  Amstrad E3 FIQ handling
   3  *
   4  *  Copyright (C) 2009 Janusz Krzysztofik
   5  *  Copyright (c) 2006 Matt Callow
   6  *  Copyright (c) 2004 Amstrad Plc
   7  *  Copyright (C) 2001 RidgeRun, Inc.
   8  *
   9  * Parts of this code are taken from linux/arch/arm/mach-omap/irq.c
  10  * in the MontaVista 2.4 kernel (and the Amstrad changes therein)
  11  *
  12  * This program is free software; you can redistribute it and/or modify it
  13  * under the terms of the GNU General Public License version 2 as published by
  14  * the Free Software Foundation.
  15  */
  16 #include <linux/gpio.h>
  17 #include <linux/interrupt.h>
  18 #include <linux/irq.h>
  19 #include <linux/module.h>
  20 #include <linux/io.h>
  21
  22 #include <plat/board-ams-delta.h>
  23
  24 #include <asm/fiq.h>
  25 #include <mach/ams-delta-fiq.h>
  26
  27 static struct fiq_handler fh = {
  28         .name   = "ams-delta-fiq"
  29 };
  30
  31 /*
  32  * This buffer is shared between FIQ and IRQ contexts.
  33  * The FIQ and IRQ isrs can both read and write it.
  34  * It is structured as a header section several 32bit slots,
  35  * followed by the circular buffer where the FIQ isr stores
  36  * keystrokes received from the qwerty keyboard.
  37  * See ams-delta-fiq.h for details of offsets.
  38  */
  39 unsigned int fiq_buffer[1024];
  40 EXPORT_SYMBOL(fiq_buffer);
  41
  42 static unsigned int irq_counter[16];
  43
  44 static irqreturn_t deferred_fiq(int irq, void *dev_id)
  45 {
  46         struct irq_desc *irq_desc;
  47         struct irq_chip *irq_chip = NULL;
  48         int gpio, irq_num, fiq_count;
  49
  50         irq_desc = irq_to_desc(IH_GPIO_BASE);
  51         if (irq_desc)
  52                 irq_chip = irq_desc->chip;
  53
  54         /*
  55          * For each handled GPIO interrupt, keep calling its interrupt handler
  56          * until the IRQ counter catches the FIQ incremented interrupt counter.
  57          */
  58         for (gpio = AMS_DELTA_GPIO_PIN_KEYBRD_CLK;
  59                         gpio <= AMS_DELTA_GPIO_PIN_HOOK_SWITCH; gpio++) {
  60                 irq_num = gpio_to_irq(gpio);
  61                 fiq_count = fiq_buffer[FIQ_CNT_INT_00 + gpio];
  62
  63                 while (irq_counter[gpio] < fiq_count) {
  64                         if (gpio != AMS_DELTA_GPIO_PIN_KEYBRD_CLK) {
  65                                 /*
  66                                  * It looks like handle_edge_irq() that
  67                                  * OMAP GPIO edge interrupts default to,
  68                                  * expects interrupt already unmasked.
  69                                  */
  70                                 if (irq_chip && irq_chip->unmask)
  71                                         irq_chip->unmask(irq_num);
  72                         }
  73                         generic_handle_irq(irq_num);
  74
  75                         irq_counter[gpio]++;
  76                 }
  77         }
  78         return IRQ_HANDLED;
  79 }
  80
  81 void __init ams_delta_init_fiq(void)
  82 {
  83         void *fiqhandler_start;
  84         unsigned int fiqhandler_length;
  85         struct pt_regs FIQ_regs;
  86         unsigned long val, offset;
  87         int i, retval;
  88
  89         fiqhandler_start = &qwerty_fiqin_start;
  90         fiqhandler_length = &qwerty_fiqin_end - &qwerty_fiqin_start;
  91         pr_info("Installing fiq handler from %p, length 0x%x\n",
  92                         fiqhandler_start, fiqhandler_length);
  93
  94         retval = claim_fiq(&fh);
  95         if (retval) {
  96                 pr_err("ams_delta_init_fiq(): couldn't claim FIQ, ret=%d\n",
  97                                 retval);
  98                 return;
  99         }
 100
 101         retval = request_irq(INT_DEFERRED_FIQ, deferred_fiq,
 102                         IRQ_TYPE_EDGE_RISING, "deferred_fiq", 0);
 103         if (retval < 0) {
 104                 pr_err("Failed to get deferred_fiq IRQ, ret=%d\n", retval);
 105                 release_fiq(&fh);
 106                 return;
 107         }
 108         /*
 109          * Since no set_type() method is provided by OMAP irq chip,
 110          * switch to edge triggered interrupt type manually.
 111          */
 112         offset = IRQ_ILR0_REG_OFFSET + INT_DEFERRED_FIQ * 0x4;
 113         val = omap_readl(DEFERRED_FIQ_IH_BASE + offset) & ~(1 << 1);
 114         omap_writel(val, DEFERRED_FIQ_IH_BASE + offset);
 115
 116         set_fiq_handler(fiqhandler_start, fiqhandler_length);
 117
 118         /*
 119          * Initialise the buffer which is shared
 120          * between FIQ mode and IRQ mode
 121          */
 122         fiq_buffer[FIQ_GPIO_INT_MASK]   = 0;
 123         fiq_buffer[FIQ_MASK]            = 0;
 124         fiq_buffer[FIQ_STATE]           = 0;
 125         fiq_buffer[FIQ_KEY]             = 0;
 126         fiq_buffer[FIQ_KEYS_CNT]        = 0;
 127         fiq_buffer[FIQ_KEYS_HICNT]      = 0;
 128         fiq_buffer[FIQ_TAIL_OFFSET]     = 0;
 129         fiq_buffer[FIQ_HEAD_OFFSET]     = 0;
 130         fiq_buffer[FIQ_BUF_LEN]         = 256;
 131         fiq_buffer[FIQ_MISSED_KEYS]     = 0;
 132         fiq_buffer[FIQ_BUFFER_START]    =
 133                         (unsigned int) &fiq_buffer[FIQ_CIRC_BUFF];
 134
 135         for (i = FIQ_CNT_INT_00; i <= FIQ_CNT_INT_15; i++)
 136                 fiq_buffer[i] = 0;
 137
 138         /*
 139          * FIQ mode r9 always points to the fiq_buffer, becauses the FIQ isr
 140          * will run in an unpredictable context. The fiq_buffer is the FIQ isr's
 141          * only means of communication with the IRQ level and other kernel
 142          * context code.
 143          */
 144         FIQ_regs.ARM_r9 = (unsigned int)fiq_buffer;
 145         set_fiq_regs(&FIQ_regs);
 146
 147         pr_info("request_fiq(): fiq_buffer = %p\n", fiq_buffer);
 148
 149         /*
 150          * Redirect GPIO interrupts to FIQ
 151          */
 152         offset = IRQ_ILR0_REG_OFFSET + INT_GPIO_BANK1 * 0x4;
 153         val = omap_readl(OMAP_IH1_BASE + offset) | 1;
 154         omap_writel(val, OMAP_IH1_BASE + offset);
 155 }