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

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *  Amstrad E3 FIQ handling
   4  *
   5  *  Copyright (C) 2009 Janusz Krzysztofik
   6  *  Copyright (c) 2006 Matt Callow
   7  *  Copyright (c) 2004 Amstrad Plc
   8  *  Copyright (C) 2001 RidgeRun, Inc.
   9  *
  10  * Parts of this code are taken from linux/arch/arm/mach-omap/irq.c
  11  * in the MontaVista 2.4 kernel (and the Amstrad changes therein)
  12  */
  13 #include <linux/gpio/consumer.h>
  14 #include <linux/gpio/machine.h>
  15 #include <linux/gpio/driver.h>
  16 #include <linux/interrupt.h>
  17 #include <linux/irq.h>
  18 #include <linux/module.h>
  19 #include <linux/io.h>
  20 #include <linux/platform_data/ams-delta-fiq.h>
  21 #include <linux/platform_device.h>
  22
  23 #include <asm/fiq.h>
  24 #include <linux/soc/ti/omap1-io.h>
  25
  26 #include "hardware.h"
  27 #include "ams-delta-fiq.h"
  28 #include "board-ams-delta.h"
  29
  30 static struct fiq_handler fh = {
  31         .name   = "ams-delta-fiq"
  32 };
  33
  34 /*
  35  * This buffer is shared between FIQ and IRQ contexts.
  36  * The FIQ and IRQ isrs can both read and write it.
  37  * It is structured as a header section several 32bit slots,
  38  * followed by the circular buffer where the FIQ isr stores
  39  * keystrokes received from the qwerty keyboard.  See
  40  * <linux/platform_data/ams-delta-fiq.h> for details of offsets.
  41  */
  42 static unsigned int fiq_buffer[1024];
  43
  44 static struct irq_chip *irq_chip;
  45 static struct irq_data *irq_data[16];
  46 static unsigned int irq_counter[16];
  47
  48 static const char *pin_name[16] __initconst = {
  49         [AMS_DELTA_GPIO_PIN_KEYBRD_DATA]        = "keybrd_data",
  50         [AMS_DELTA_GPIO_PIN_KEYBRD_CLK]         = "keybrd_clk",
  51 };
  52
  53 static irqreturn_t deferred_fiq(int irq, void *dev_id)
  54 {
  55         struct irq_data *d;
  56         int gpio, irq_num, fiq_count;
  57
  58         /*
  59          * For each handled GPIO interrupt, keep calling its interrupt handler
  60          * until the IRQ counter catches the FIQ incremented interrupt counter.
  61          */
  62         for (gpio = AMS_DELTA_GPIO_PIN_KEYBRD_CLK;
  63                         gpio <= AMS_DELTA_GPIO_PIN_HOOK_SWITCH; gpio++) {
  64                 d = irq_data[gpio];
  65                 irq_num = d->irq;
  66                 fiq_count = fiq_buffer[FIQ_CNT_INT_00 + gpio];
  67
  68                 if (irq_counter[gpio] < fiq_count &&
  69                                 gpio != AMS_DELTA_GPIO_PIN_KEYBRD_CLK) {
  70                         /*
  71                          * handle_simple_irq() that OMAP GPIO edge
  72                          * interrupts default to since commit 80ac93c27441
  73                          * requires interrupt already acked and unmasked.
  74                          */
  75                         if (!WARN_ON_ONCE(!irq_chip->irq_unmask))
  76                                 irq_chip->irq_unmask(d);
  77                 }
  78                 for (; irq_counter[gpio] < fiq_count; irq_counter[gpio]++)
  79                         generic_handle_irq(irq_num);
  80         }
  81         return IRQ_HANDLED;
  82 }
  83
  84 void __init ams_delta_init_fiq(struct gpio_chip *chip,
  85                                struct platform_device *serio)
  86 {
  87         struct gpio_desc *gpiod, *data = NULL, *clk = NULL;
  88         void *fiqhandler_start;
  89         unsigned int fiqhandler_length;
  90         struct pt_regs FIQ_regs;
  91         unsigned long val, offset;
  92         int i, retval;
  93
  94         /* Store irq_chip location for IRQ handler use */
  95         irq_chip = chip->irq.chip;
  96         if (!irq_chip) {
  97                 pr_err("%s: GPIO chip %s is missing IRQ function\n", __func__,
  98                        chip->label);
  99                 return;
 100         }
 101
 102         for (i = 0; i < ARRAY_SIZE(irq_data); i++) {
 103                 gpiod = gpiochip_request_own_desc(chip, i, pin_name[i],
 104                                                   GPIO_ACTIVE_HIGH, GPIOD_IN);
 105                 if (IS_ERR(gpiod)) {
 106                         pr_err("%s: failed to get GPIO pin %d (%ld)\n",
 107                                __func__, i, PTR_ERR(gpiod));
 108                         return;
 109                 }
 110                 /* Store irq_data location for IRQ handler use */
 111                 irq_data[i] = irq_get_irq_data(gpiod_to_irq(gpiod));
 112
 113                 /*
 114                  * FIQ handler takes full control over serio data and clk GPIO
 115                  * pins.  Initialize them and keep requested so nobody can
 116                  * interfere.  Fail if any of those two couldn't be requested.
 117                  */
 118                 switch (i) {
 119                 case AMS_DELTA_GPIO_PIN_KEYBRD_DATA:
 120                         data = gpiod;
 121                         gpiod_direction_input(data);
 122                         break;
 123                 case AMS_DELTA_GPIO_PIN_KEYBRD_CLK:
 124                         clk = gpiod;
 125                         gpiod_direction_input(clk);
 126                         break;
 127                 default:
 128                         gpiochip_free_own_desc(gpiod);
 129                         break;
 130                 }
 131         }
 132         if (!data || !clk)
 133                 goto out_gpio;
 134
 135         fiqhandler_start = &qwerty_fiqin_start;
 136         fiqhandler_length = &qwerty_fiqin_end - &qwerty_fiqin_start;
 137         pr_info("Installing fiq handler from %p, length 0x%x\n",
 138                         fiqhandler_start, fiqhandler_length);
 139
 140         retval = claim_fiq(&fh);
 141         if (retval) {
 142                 pr_err("ams_delta_init_fiq(): couldn't claim FIQ, ret=%d\n",
 143                                 retval);
 144                 goto out_gpio;
 145         }
 146
 147         retval = request_irq(INT_DEFERRED_FIQ, deferred_fiq,
 148                         IRQ_TYPE_EDGE_RISING, "deferred_fiq", NULL);
 149         if (retval < 0) {
 150                 pr_err("Failed to get deferred_fiq IRQ, ret=%d\n", retval);
 151                 release_fiq(&fh);
 152                 goto out_gpio;
 153         }
 154         /*
 155          * Since no set_type() method is provided by OMAP irq chip,
 156          * switch to edge triggered interrupt type manually.
 157          */
 158         offset = IRQ_ILR0_REG_OFFSET +
 159                         ((INT_DEFERRED_FIQ - NR_IRQS_LEGACY) & 0x1f) * 0x4;
 160         val = omap_readl(DEFERRED_FIQ_IH_BASE + offset) & ~(1 << 1);
 161         omap_writel(val, DEFERRED_FIQ_IH_BASE + offset);
 162
 163         set_fiq_handler(fiqhandler_start, fiqhandler_length);
 164
 165         /*
 166          * Initialise the buffer which is shared
 167          * between FIQ mode and IRQ mode
 168          */
 169         fiq_buffer[FIQ_GPIO_INT_MASK]   = 0;
 170         fiq_buffer[FIQ_MASK]            = 0;
 171         fiq_buffer[FIQ_STATE]           = 0;
 172         fiq_buffer[FIQ_KEY]             = 0;
 173         fiq_buffer[FIQ_KEYS_CNT]        = 0;
 174         fiq_buffer[FIQ_KEYS_HICNT]      = 0;
 175         fiq_buffer[FIQ_TAIL_OFFSET]     = 0;
 176         fiq_buffer[FIQ_HEAD_OFFSET]     = 0;
 177         fiq_buffer[FIQ_BUF_LEN]         = 256;
 178         fiq_buffer[FIQ_MISSED_KEYS]     = 0;
 179         fiq_buffer[FIQ_BUFFER_START]    =
 180                         (unsigned int) &fiq_buffer[FIQ_CIRC_BUFF];
 181
 182         for (i = FIQ_CNT_INT_00; i <= FIQ_CNT_INT_15; i++)
 183                 fiq_buffer[i] = 0;
 184
 185         /*
 186          * FIQ mode r9 always points to the fiq_buffer, because the FIQ isr
 187          * will run in an unpredictable context. The fiq_buffer is the FIQ isr's
 188          * only means of communication with the IRQ level and other kernel
 189          * context code.
 190          */
 191         FIQ_regs.ARM_r9 = (unsigned int)fiq_buffer;
 192         set_fiq_regs(&FIQ_regs);
 193
 194         pr_info("request_fiq(): fiq_buffer = %p\n", fiq_buffer);
 195
 196         /*
 197          * Redirect GPIO interrupts to FIQ
 198          */
 199         offset = IRQ_ILR0_REG_OFFSET + (INT_GPIO_BANK1 - NR_IRQS_LEGACY) * 0x4;
 200         val = omap_readl(OMAP_IH1_BASE + offset) | 1;
 201         omap_writel(val, OMAP_IH1_BASE + offset);
 202
 203         /* Initialize serio device IRQ resource and platform_data */
 204         serio->resource[0].start = gpiod_to_irq(clk);
 205         serio->resource[0].end = serio->resource[0].start;
 206         serio->dev.platform_data = fiq_buffer;
 207
 208         /*
 209          * Since FIQ handler performs handling of GPIO registers for
 210          * "keybrd_clk" IRQ pin, ams_delta_serio driver used to set
 211          * handle_simple_irq() as active IRQ handler for that pin to avoid
 212          * bad interaction with gpio-omap driver.  This is no longer needed
 213          * as handle_simple_irq() is now the default handler for OMAP GPIO
 214          * edge interrupts.
 215          * This comment replaces the obsolete code which has been removed
 216          * from the ams_delta_serio driver and stands here only as a reminder
 217          * of that dependency on gpio-omap driver behavior.
 218          */
 219
 220         return;
 221
 222 out_gpio:
 223         if (data)
 224                 gpiochip_free_own_desc(data);
 225         if (clk)
 226                 gpiochip_free_own_desc(clk);
 227 }