1 /* 2 * Kontron PLD GPIO driver 3 * 4 * Copyright (c) 2010-2013 Kontron Europe GmbH 5 * Author: Michael Brunner <michael.brunner@kontron.com> 6 * 7 * This program is free software; you can redistribute it and/or modify 8 * it under the terms of the GNU General Public License 2 as published 9 * by the Free Software Foundation. 10 * 11 * This program is distributed in the hope that it will be useful, 12 * but WITHOUT ANY WARRANTY; without even the implied warranty of 13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 * GNU General Public License for more details. 15 */ 16 17 #include <linux/init.h> 18 #include <linux/kernel.h> 19 #include <linux/module.h> 20 #include <linux/bitops.h> 21 #include <linux/errno.h> 22 #include <linux/platform_device.h> 23 #include <linux/gpio.h> 24 #include <linux/mfd/kempld.h> 25 26 #define KEMPLD_GPIO_MAX_NUM 16 27 #define KEMPLD_GPIO_MASK(x) (BIT((x) % 8)) 28 #define KEMPLD_GPIO_DIR_NUM(x) (0x40 + (x) / 8) 29 #define KEMPLD_GPIO_LVL_NUM(x) (0x42 + (x) / 8) 30 #define KEMPLD_GPIO_EVT_LVL_EDGE 0x46 31 #define KEMPLD_GPIO_IEN 0x4A 32 33 struct kempld_gpio_data { 34 struct gpio_chip chip; 35 struct kempld_device_data *pld; 36 }; 37 38 /* 39 * Set or clear GPIO bit 40 * kempld_get_mutex must be called prior to calling this function. 41 */ 42 static void kempld_gpio_bitop(struct kempld_device_data *pld, 43 u8 reg, u8 bit, u8 val) 44 { 45 u8 status; 46 47 status = kempld_read8(pld, reg); 48 if (val) 49 status |= KEMPLD_GPIO_MASK(bit); 50 else 51 status &= ~KEMPLD_GPIO_MASK(bit); 52 kempld_write8(pld, reg, status); 53 } 54 55 static int kempld_gpio_get_bit(struct kempld_device_data *pld, u8 reg, u8 bit) 56 { 57 u8 status; 58 59 kempld_get_mutex(pld); 60 status = kempld_read8(pld, reg); 61 kempld_release_mutex(pld); 62 63 return !!(status & KEMPLD_GPIO_MASK(bit)); 64 } 65 66 static int kempld_gpio_get(struct gpio_chip *chip, unsigned offset) 67 { 68 struct kempld_gpio_data *gpio 69 = container_of(chip, struct kempld_gpio_data, chip); 70 struct kempld_device_data *pld = gpio->pld; 71 72 return kempld_gpio_get_bit(pld, KEMPLD_GPIO_LVL_NUM(offset), offset); 73 } 74 75 static void kempld_gpio_set(struct gpio_chip *chip, unsigned offset, int value) 76 { 77 struct kempld_gpio_data *gpio 78 = container_of(chip, struct kempld_gpio_data, chip); 79 struct kempld_device_data *pld = gpio->pld; 80 81 kempld_get_mutex(pld); 82 kempld_gpio_bitop(pld, KEMPLD_GPIO_LVL_NUM(offset), offset, value); 83 kempld_release_mutex(pld); 84 } 85 86 static int kempld_gpio_direction_input(struct gpio_chip *chip, unsigned offset) 87 { 88 struct kempld_gpio_data *gpio 89 = container_of(chip, struct kempld_gpio_data, chip); 90 struct kempld_device_data *pld = gpio->pld; 91 92 kempld_get_mutex(pld); 93 kempld_gpio_bitop(pld, KEMPLD_GPIO_DIR_NUM(offset), offset, 0); 94 kempld_release_mutex(pld); 95 96 return 0; 97 } 98 99 static int kempld_gpio_direction_output(struct gpio_chip *chip, unsigned offset, 100 int value) 101 { 102 struct kempld_gpio_data *gpio 103 = container_of(chip, struct kempld_gpio_data, chip); 104 struct kempld_device_data *pld = gpio->pld; 105 106 kempld_get_mutex(pld); 107 kempld_gpio_bitop(pld, KEMPLD_GPIO_LVL_NUM(offset), offset, value); 108 kempld_gpio_bitop(pld, KEMPLD_GPIO_DIR_NUM(offset), offset, 1); 109 kempld_release_mutex(pld); 110 111 return 0; 112 } 113 114 static int kempld_gpio_get_direction(struct gpio_chip *chip, unsigned offset) 115 { 116 struct kempld_gpio_data *gpio 117 = container_of(chip, struct kempld_gpio_data, chip); 118 struct kempld_device_data *pld = gpio->pld; 119 120 return !kempld_gpio_get_bit(pld, KEMPLD_GPIO_DIR_NUM(offset), offset); 121 } 122 123 static int kempld_gpio_pincount(struct kempld_device_data *pld) 124 { 125 u16 evt, evt_back; 126 127 kempld_get_mutex(pld); 128 129 /* Backup event register as it might be already initialized */ 130 evt_back = kempld_read16(pld, KEMPLD_GPIO_EVT_LVL_EDGE); 131 /* Clear event register */ 132 kempld_write16(pld, KEMPLD_GPIO_EVT_LVL_EDGE, 0x0000); 133 /* Read back event register */ 134 evt = kempld_read16(pld, KEMPLD_GPIO_EVT_LVL_EDGE); 135 /* Restore event register */ 136 kempld_write16(pld, KEMPLD_GPIO_EVT_LVL_EDGE, evt_back); 137 138 kempld_release_mutex(pld); 139 140 return evt ? __ffs(evt) : 16; 141 } 142 143 static int kempld_gpio_probe(struct platform_device *pdev) 144 { 145 struct device *dev = &pdev->dev; 146 struct kempld_device_data *pld = dev_get_drvdata(dev->parent); 147 struct kempld_platform_data *pdata = dev_get_platdata(pld->dev); 148 struct kempld_gpio_data *gpio; 149 struct gpio_chip *chip; 150 int ret; 151 152 if (pld->info.spec_major < 2) { 153 dev_err(dev, 154 "Driver only supports GPIO devices compatible to PLD spec. rev. 2.0 or higher\n"); 155 return -ENODEV; 156 } 157 158 gpio = devm_kzalloc(dev, sizeof(*gpio), GFP_KERNEL); 159 if (!gpio) 160 return -ENOMEM; 161 162 gpio->pld = pld; 163 164 platform_set_drvdata(pdev, gpio); 165 166 chip = &gpio->chip; 167 chip->label = "gpio-kempld"; 168 chip->owner = THIS_MODULE; 169 chip->dev = dev; 170 chip->can_sleep = true; 171 if (pdata && pdata->gpio_base) 172 chip->base = pdata->gpio_base; 173 else 174 chip->base = -1; 175 chip->direction_input = kempld_gpio_direction_input; 176 chip->direction_output = kempld_gpio_direction_output; 177 chip->get_direction = kempld_gpio_get_direction; 178 chip->get = kempld_gpio_get; 179 chip->set = kempld_gpio_set; 180 chip->ngpio = kempld_gpio_pincount(pld); 181 if (chip->ngpio == 0) { 182 dev_err(dev, "No GPIO pins detected\n"); 183 return -ENODEV; 184 } 185 186 ret = gpiochip_add(chip); 187 if (ret) { 188 dev_err(dev, "Could not register GPIO chip\n"); 189 return ret; 190 } 191 192 dev_info(dev, "GPIO functionality initialized with %d pins\n", 193 chip->ngpio); 194 195 return 0; 196 } 197 198 static int kempld_gpio_remove(struct platform_device *pdev) 199 { 200 struct kempld_gpio_data *gpio = platform_get_drvdata(pdev); 201 202 gpiochip_remove(&gpio->chip); 203 return 0; 204 } 205 206 static struct platform_driver kempld_gpio_driver = { 207 .driver = { 208 .name = "kempld-gpio", 209 }, 210 .probe = kempld_gpio_probe, 211 .remove = kempld_gpio_remove, 212 }; 213 214 module_platform_driver(kempld_gpio_driver); 215 216 MODULE_DESCRIPTION("KEM PLD GPIO Driver"); 217 MODULE_AUTHOR("Michael Brunner <michael.brunner@kontron.com>"); 218 MODULE_LICENSE("GPL"); 219 MODULE_ALIAS("platform:kempld-gpio"); 220