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