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/driver.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 = gpiochip_get_data(chip); 69 struct kempld_device_data *pld = gpio->pld; 70 71 return !!kempld_gpio_get_bit(pld, KEMPLD_GPIO_LVL_NUM(offset), offset); 72 } 73 74 static void kempld_gpio_set(struct gpio_chip *chip, unsigned offset, int value) 75 { 76 struct kempld_gpio_data *gpio = gpiochip_get_data(chip); 77 struct kempld_device_data *pld = gpio->pld; 78 79 kempld_get_mutex(pld); 80 kempld_gpio_bitop(pld, KEMPLD_GPIO_LVL_NUM(offset), offset, value); 81 kempld_release_mutex(pld); 82 } 83 84 static int kempld_gpio_direction_input(struct gpio_chip *chip, unsigned offset) 85 { 86 struct kempld_gpio_data *gpio = gpiochip_get_data(chip); 87 struct kempld_device_data *pld = gpio->pld; 88 89 kempld_get_mutex(pld); 90 kempld_gpio_bitop(pld, KEMPLD_GPIO_DIR_NUM(offset), offset, 0); 91 kempld_release_mutex(pld); 92 93 return 0; 94 } 95 96 static int kempld_gpio_direction_output(struct gpio_chip *chip, unsigned offset, 97 int value) 98 { 99 struct kempld_gpio_data *gpio = gpiochip_get_data(chip); 100 struct kempld_device_data *pld = gpio->pld; 101 102 kempld_get_mutex(pld); 103 kempld_gpio_bitop(pld, KEMPLD_GPIO_LVL_NUM(offset), offset, value); 104 kempld_gpio_bitop(pld, KEMPLD_GPIO_DIR_NUM(offset), offset, 1); 105 kempld_release_mutex(pld); 106 107 return 0; 108 } 109 110 static int kempld_gpio_get_direction(struct gpio_chip *chip, unsigned offset) 111 { 112 struct kempld_gpio_data *gpio = gpiochip_get_data(chip); 113 struct kempld_device_data *pld = gpio->pld; 114 115 return !kempld_gpio_get_bit(pld, KEMPLD_GPIO_DIR_NUM(offset), offset); 116 } 117 118 static int kempld_gpio_pincount(struct kempld_device_data *pld) 119 { 120 u16 evt, evt_back; 121 122 kempld_get_mutex(pld); 123 124 /* Backup event register as it might be already initialized */ 125 evt_back = kempld_read16(pld, KEMPLD_GPIO_EVT_LVL_EDGE); 126 /* Clear event register */ 127 kempld_write16(pld, KEMPLD_GPIO_EVT_LVL_EDGE, 0x0000); 128 /* Read back event register */ 129 evt = kempld_read16(pld, KEMPLD_GPIO_EVT_LVL_EDGE); 130 /* Restore event register */ 131 kempld_write16(pld, KEMPLD_GPIO_EVT_LVL_EDGE, evt_back); 132 133 kempld_release_mutex(pld); 134 135 return evt ? __ffs(evt) : 16; 136 } 137 138 static int kempld_gpio_probe(struct platform_device *pdev) 139 { 140 struct device *dev = &pdev->dev; 141 struct kempld_device_data *pld = dev_get_drvdata(dev->parent); 142 struct kempld_platform_data *pdata = dev_get_platdata(pld->dev); 143 struct kempld_gpio_data *gpio; 144 struct gpio_chip *chip; 145 int ret; 146 147 if (pld->info.spec_major < 2) { 148 dev_err(dev, 149 "Driver only supports GPIO devices compatible to PLD spec. rev. 2.0 or higher\n"); 150 return -ENODEV; 151 } 152 153 gpio = devm_kzalloc(dev, sizeof(*gpio), GFP_KERNEL); 154 if (!gpio) 155 return -ENOMEM; 156 157 gpio->pld = pld; 158 159 platform_set_drvdata(pdev, gpio); 160 161 chip = &gpio->chip; 162 chip->label = "gpio-kempld"; 163 chip->owner = THIS_MODULE; 164 chip->parent = dev; 165 chip->can_sleep = true; 166 if (pdata && pdata->gpio_base) 167 chip->base = pdata->gpio_base; 168 else 169 chip->base = -1; 170 chip->direction_input = kempld_gpio_direction_input; 171 chip->direction_output = kempld_gpio_direction_output; 172 chip->get_direction = kempld_gpio_get_direction; 173 chip->get = kempld_gpio_get; 174 chip->set = kempld_gpio_set; 175 chip->ngpio = kempld_gpio_pincount(pld); 176 if (chip->ngpio == 0) { 177 dev_err(dev, "No GPIO pins detected\n"); 178 return -ENODEV; 179 } 180 181 ret = devm_gpiochip_add_data(dev, chip, gpio); 182 if (ret) { 183 dev_err(dev, "Could not register GPIO chip\n"); 184 return ret; 185 } 186 187 dev_info(dev, "GPIO functionality initialized with %d pins\n", 188 chip->ngpio); 189 190 return 0; 191 } 192 193 static struct platform_driver kempld_gpio_driver = { 194 .driver = { 195 .name = "kempld-gpio", 196 }, 197 .probe = kempld_gpio_probe, 198 }; 199 200 module_platform_driver(kempld_gpio_driver); 201 202 MODULE_DESCRIPTION("KEM PLD GPIO Driver"); 203 MODULE_AUTHOR("Michael Brunner <michael.brunner@kontron.com>"); 204 MODULE_LICENSE("GPL"); 205 MODULE_ALIAS("platform:kempld-gpio"); 206