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