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/driver.h> 15 #include <linux/interrupt.h> 16 #include <linux/irq.h> 17 #include <linux/module.h> 18 #include <linux/io.h> 19 #include <linux/platform_data/ams-delta-fiq.h> 20 #include <linux/platform_device.h> 21 22 #include <asm/fiq.h> 23 24 #include "ams-delta-fiq.h" 25 #include "board-ams-delta.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. See 37 * <linux/platform_data/ams-delta-fiq.h> for details of offsets. 38 */ 39 static unsigned int fiq_buffer[1024]; 40 41 static struct irq_chip *irq_chip; 42 static struct irq_data *irq_data[16]; 43 static unsigned int irq_counter[16]; 44 45 static const char *pin_name[16] __initconst = { 46 [AMS_DELTA_GPIO_PIN_KEYBRD_DATA] = "keybrd_data", 47 [AMS_DELTA_GPIO_PIN_KEYBRD_CLK] = "keybrd_clk", 48 }; 49 50 static irqreturn_t deferred_fiq(int irq, void *dev_id) 51 { 52 struct irq_data *d; 53 int gpio, irq_num, fiq_count; 54 55 /* 56 * For each handled GPIO interrupt, keep calling its interrupt handler 57 * until the IRQ counter catches the FIQ incremented interrupt counter. 58 */ 59 for (gpio = AMS_DELTA_GPIO_PIN_KEYBRD_CLK; 60 gpio <= AMS_DELTA_GPIO_PIN_HOOK_SWITCH; gpio++) { 61 d = irq_data[gpio]; 62 irq_num = d->irq; 63 fiq_count = fiq_buffer[FIQ_CNT_INT_00 + gpio]; 64 65 if (irq_counter[gpio] < fiq_count && 66 gpio != AMS_DELTA_GPIO_PIN_KEYBRD_CLK) { 67 /* 68 * handle_simple_irq() that OMAP GPIO edge 69 * interrupts default to since commit 80ac93c27441 70 * requires interrupt already acked and unmasked. 71 */ 72 if (irq_chip->irq_ack) 73 irq_chip->irq_ack(d); 74 if (irq_chip->irq_unmask) 75 irq_chip->irq_unmask(d); 76 } 77 for (; irq_counter[gpio] < fiq_count; irq_counter[gpio]++) 78 generic_handle_irq(irq_num); 79 } 80 return IRQ_HANDLED; 81 } 82 83 void __init ams_delta_init_fiq(struct gpio_chip *chip, 84 struct platform_device *serio) 85 { 86 struct gpio_desc *gpiod, *data = NULL, *clk = NULL; 87 void *fiqhandler_start; 88 unsigned int fiqhandler_length; 89 struct pt_regs FIQ_regs; 90 unsigned long val, offset; 91 int i, retval; 92 93 /* Store irq_chip location for IRQ handler use */ 94 irq_chip = chip->irq.chip; 95 if (!irq_chip) { 96 pr_err("%s: GPIO chip %s is missing IRQ function\n", __func__, 97 chip->label); 98 return; 99 } 100 101 for (i = 0; i < ARRAY_SIZE(irq_data); i++) { 102 gpiod = gpiochip_request_own_desc(chip, i, pin_name[i], 0); 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 } 226