arch/arm/mach-omap1/fpga.c

   1 /*
   2  * linux/arch/arm/mach-omap1/fpga.c
   3  *
   4  * Interrupt handler for OMAP-1510 Innovator FPGA
   5  *
   6  * Copyright (C) 2001 RidgeRun, Inc.
   7  * Author: Greg Lonnon <glonnon@ridgerun.com>
   8  *
   9  * Copyright (C) 2002 MontaVista Software, Inc.
  10  *
  11  * Separated FPGA interrupts from innovator1510.c and cleaned up for 2.6
  12  * Copyright (C) 2004 Nokia Corporation by Tony Lindrgen <tony@atomide.com>
  13  *
  14  * This program is free software; you can redistribute it and/or modify
  15  * it under the terms of the GNU General Public License version 2 as
  16  * published by the Free Software Foundation.
  17  */
  18
  19 #include <linux/types.h>
  20 #include <linux/gpio.h>
  21 #include <linux/init.h>
  22 #include <linux/kernel.h>
  23 #include <linux/device.h>
  24 #include <linux/errno.h>
  25 #include <linux/io.h>
  26
  27 #include <asm/irq.h>
  28 #include <asm/mach/irq.h>
  29
  30 #include <mach/hardware.h>
  31
  32 #include "iomap.h"
  33 #include "common.h"
  34 #include "fpga.h"
  35
  36 static void fpga_mask_irq(struct irq_data *d)
  37 {
  38         unsigned int irq = d->irq - OMAP_FPGA_IRQ_BASE;
  39
  40         if (irq < 8)
  41                 __raw_writeb((__raw_readb(OMAP1510_FPGA_IMR_LO)
  42                               & ~(1 << irq)), OMAP1510_FPGA_IMR_LO);
  43         else if (irq < 16)
  44                 __raw_writeb((__raw_readb(OMAP1510_FPGA_IMR_HI)
  45                               & ~(1 << (irq - 8))), OMAP1510_FPGA_IMR_HI);
  46         else
  47                 __raw_writeb((__raw_readb(INNOVATOR_FPGA_IMR2)
  48                               & ~(1 << (irq - 16))), INNOVATOR_FPGA_IMR2);
  49 }
  50
  51
  52 static inline u32 get_fpga_unmasked_irqs(void)
  53 {
  54         return
  55                 ((__raw_readb(OMAP1510_FPGA_ISR_LO) &
  56                   __raw_readb(OMAP1510_FPGA_IMR_LO))) |
  57                 ((__raw_readb(OMAP1510_FPGA_ISR_HI) &
  58                   __raw_readb(OMAP1510_FPGA_IMR_HI)) << 8) |
  59                 ((__raw_readb(INNOVATOR_FPGA_ISR2) &
  60                   __raw_readb(INNOVATOR_FPGA_IMR2)) << 16);
  61 }
  62
  63
  64 static void fpga_ack_irq(struct irq_data *d)
  65 {
  66         /* Don't need to explicitly ACK FPGA interrupts */
  67 }
  68
  69 static void fpga_unmask_irq(struct irq_data *d)
  70 {
  71         unsigned int irq = d->irq - OMAP_FPGA_IRQ_BASE;
  72
  73         if (irq < 8)
  74                 __raw_writeb((__raw_readb(OMAP1510_FPGA_IMR_LO) | (1 << irq)),
  75                      OMAP1510_FPGA_IMR_LO);
  76         else if (irq < 16)
  77                 __raw_writeb((__raw_readb(OMAP1510_FPGA_IMR_HI)
  78                               | (1 << (irq - 8))), OMAP1510_FPGA_IMR_HI);
  79         else
  80                 __raw_writeb((__raw_readb(INNOVATOR_FPGA_IMR2)
  81                               | (1 << (irq - 16))), INNOVATOR_FPGA_IMR2);
  82 }
  83
  84 static void fpga_mask_ack_irq(struct irq_data *d)
  85 {
  86         fpga_mask_irq(d);
  87         fpga_ack_irq(d);
  88 }
  89
  90 static void innovator_fpga_IRQ_demux(unsigned int irq, struct irq_desc *desc)
  91 {
  92         u32 stat;
  93         int fpga_irq;
  94
  95         stat = get_fpga_unmasked_irqs();
  96
  97         if (!stat)
  98                 return;
  99
 100         for (fpga_irq = OMAP_FPGA_IRQ_BASE;
 101              (fpga_irq < OMAP_FPGA_IRQ_END) && stat;
 102              fpga_irq++, stat >>= 1) {
 103                 if (stat & 1) {
 104                         generic_handle_irq(fpga_irq);
 105                 }
 106         }
 107 }
 108
 109 static struct irq_chip omap_fpga_irq_ack = {
 110         .name           = "FPGA-ack",
 111         .irq_ack        = fpga_mask_ack_irq,
 112         .irq_mask       = fpga_mask_irq,
 113         .irq_unmask     = fpga_unmask_irq,
 114 };
 115
 116
 117 static struct irq_chip omap_fpga_irq = {
 118         .name           = "FPGA",
 119         .irq_ack        = fpga_ack_irq,
 120         .irq_mask       = fpga_mask_irq,
 121         .irq_unmask     = fpga_unmask_irq,
 122 };
 123
 124 /*
 125  * All of the FPGA interrupt request inputs except for the touchscreen are
 126  * edge-sensitive; the touchscreen is level-sensitive.  The edge-sensitive
 127  * interrupts are acknowledged as a side-effect of reading the interrupt
 128  * status register from the FPGA.  The edge-sensitive interrupt inputs
 129  * cause a problem with level interrupt requests, such as Ethernet.  The
 130  * problem occurs when a level interrupt request is asserted while its
 131  * interrupt input is masked in the FPGA, which results in a missed
 132  * interrupt.
 133  *
 134  * In an attempt to workaround the problem with missed interrupts, the
 135  * mask_ack routine for all of the FPGA interrupts has been changed from
 136  * fpga_mask_ack_irq() to fpga_ack_irq() so that the specific FPGA interrupt
 137  * being serviced is left unmasked.  We can do this because the FPGA cascade
 138  * interrupt is installed with the IRQF_DISABLED flag, which leaves all
 139  * interrupts masked at the CPU while an FPGA interrupt handler executes.
 140  *
 141  * Limited testing indicates that this workaround appears to be effective
 142  * for the smc9194 Ethernet driver used on the Innovator.  It should work
 143  * on other FPGA interrupts as well, but any drivers that explicitly mask
 144  * interrupts at the interrupt controller via disable_irq/enable_irq
 145  * could pose a problem.
 146  */
 147 void omap1510_fpga_init_irq(void)
 148 {
 149         int i, res;
 150
 151         __raw_writeb(0, OMAP1510_FPGA_IMR_LO);
 152         __raw_writeb(0, OMAP1510_FPGA_IMR_HI);
 153         __raw_writeb(0, INNOVATOR_FPGA_IMR2);
 154
 155         for (i = OMAP_FPGA_IRQ_BASE; i < OMAP_FPGA_IRQ_END; i++) {
 156
 157                 if (i == OMAP1510_INT_FPGA_TS) {
 158                         /*
 159                          * The touchscreen interrupt is level-sensitive, so
 160                          * we'll use the regular mask_ack routine for it.
 161                          */
 162                         irq_set_chip(i, &omap_fpga_irq_ack);
 163                 }
 164                 else {
 165                         /*
 166                          * All FPGA interrupts except the touchscreen are
 167                          * edge-sensitive, so we won't mask them.
 168                          */
 169                         irq_set_chip(i, &omap_fpga_irq);
 170                 }
 171
 172                 irq_set_handler(i, handle_edge_irq);
 173                 set_irq_flags(i, IRQF_VALID);
 174         }
 175
 176         /*
 177          * The FPGA interrupt line is connected to GPIO13. Claim this pin for
 178          * the ARM.
 179          *
 180          * NOTE: For general GPIO/MPUIO access and interrupts, please see
 181          * gpio.[ch]
 182          */
 183         res = gpio_request(13, "FPGA irq");
 184         if (res) {
 185                 pr_err("%s failed to get gpio\n", __func__);
 186                 return;
 187         }
 188         gpio_direction_input(13);
 189         irq_set_irq_type(gpio_to_irq(13), IRQ_TYPE_EDGE_RISING);
 190         irq_set_chained_handler(OMAP1510_INT_FPGA, innovator_fpga_IRQ_demux);
 191 }