1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Kontron PLD GPIO driver 4 * 5 * Copyright (c) 2010-2013 Kontron Europe GmbH 6 * Author: Michael Brunner <michael.brunner@kontron.com> 7 */ 8 9 #include <linux/init.h> 10 #include <linux/kernel.h> 11 #include <linux/module.h> 12 #include <linux/bitops.h> 13 #include <linux/errno.h> 14 #include <linux/platform_device.h> 15 #include <linux/gpio/driver.h> 16 #include <linux/mfd/kempld.h> 17 18 #define KEMPLD_GPIO_MAX_NUM 16 19 #define KEMPLD_GPIO_MASK(x) (BIT((x) % 8)) 20 #define KEMPLD_GPIO_DIR_NUM(x) (0x40 + (x) / 8) 21 #define KEMPLD_GPIO_LVL_NUM(x) (0x42 + (x) / 8) 22 #define KEMPLD_GPIO_EVT_LVL_EDGE 0x46 23 #define KEMPLD_GPIO_IEN 0x4A 24 25 struct kempld_gpio_data { 26 struct gpio_chip chip; 27 struct kempld_device_data *pld; 28 }; 29 30 /* 31 * Set or clear GPIO bit 32 * kempld_get_mutex must be called prior to calling this function. 33 */ 34 static void kempld_gpio_bitop(struct kempld_device_data *pld, 35 u8 reg, u8 bit, u8 val) 36 { 37 u8 status; 38 39 status = kempld_read8(pld, reg); 40 if (val) 41 status |= KEMPLD_GPIO_MASK(bit); 42 else 43 status &= ~KEMPLD_GPIO_MASK(bit); 44 kempld_write8(pld, reg, status); 45 } 46 47 static int kempld_gpio_get_bit(struct kempld_device_data *pld, u8 reg, u8 bit) 48 { 49 u8 status; 50 51 kempld_get_mutex(pld); 52 status = kempld_read8(pld, reg); 53 kempld_release_mutex(pld); 54 55 return !!(status & KEMPLD_GPIO_MASK(bit)); 56 } 57 58 static int kempld_gpio_get(struct gpio_chip *chip, unsigned offset) 59 { 60 struct kempld_gpio_data *gpio = gpiochip_get_data(chip); 61 struct kempld_device_data *pld = gpio->pld; 62 63 return !!kempld_gpio_get_bit(pld, KEMPLD_GPIO_LVL_NUM(offset), offset); 64 } 65 66 static void kempld_gpio_set(struct gpio_chip *chip, unsigned offset, int value) 67 { 68 struct kempld_gpio_data *gpio = gpiochip_get_data(chip); 69 struct kempld_device_data *pld = gpio->pld; 70 71 kempld_get_mutex(pld); 72 kempld_gpio_bitop(pld, KEMPLD_GPIO_LVL_NUM(offset), offset, value); 73 kempld_release_mutex(pld); 74 } 75 76 static int kempld_gpio_direction_input(struct gpio_chip *chip, unsigned offset) 77 { 78 struct kempld_gpio_data *gpio = gpiochip_get_data(chip); 79 struct kempld_device_data *pld = gpio->pld; 80 81 kempld_get_mutex(pld); 82 kempld_gpio_bitop(pld, KEMPLD_GPIO_DIR_NUM(offset), offset, 0); 83 kempld_release_mutex(pld); 84 85 return 0; 86 } 87 88 static int kempld_gpio_direction_output(struct gpio_chip *chip, unsigned offset, 89 int value) 90 { 91 struct kempld_gpio_data *gpio = gpiochip_get_data(chip); 92 struct kempld_device_data *pld = gpio->pld; 93 94 kempld_get_mutex(pld); 95 kempld_gpio_bitop(pld, KEMPLD_GPIO_LVL_NUM(offset), offset, value); 96 kempld_gpio_bitop(pld, KEMPLD_GPIO_DIR_NUM(offset), offset, 1); 97 kempld_release_mutex(pld); 98 99 return 0; 100 } 101 102 static int kempld_gpio_get_direction(struct gpio_chip *chip, unsigned offset) 103 { 104 struct kempld_gpio_data *gpio = gpiochip_get_data(chip); 105 struct kempld_device_data *pld = gpio->pld; 106 107 if (kempld_gpio_get_bit(pld, KEMPLD_GPIO_DIR_NUM(offset), offset)) 108 return GPIO_LINE_DIRECTION_OUT; 109 110 return GPIO_LINE_DIRECTION_IN; 111 } 112 113 static int kempld_gpio_pincount(struct kempld_device_data *pld) 114 { 115 u16 evt, evt_back; 116 117 kempld_get_mutex(pld); 118 119 /* Backup event register as it might be already initialized */ 120 evt_back = kempld_read16(pld, KEMPLD_GPIO_EVT_LVL_EDGE); 121 /* Clear event register */ 122 kempld_write16(pld, KEMPLD_GPIO_EVT_LVL_EDGE, 0x0000); 123 /* Read back event register */ 124 evt = kempld_read16(pld, KEMPLD_GPIO_EVT_LVL_EDGE); 125 /* Restore event register */ 126 kempld_write16(pld, KEMPLD_GPIO_EVT_LVL_EDGE, evt_back); 127 128 kempld_release_mutex(pld); 129 130 return evt ? __ffs(evt) : 16; 131 } 132 133 static int kempld_gpio_probe(struct platform_device *pdev) 134 { 135 struct device *dev = &pdev->dev; 136 struct kempld_device_data *pld = dev_get_drvdata(dev->parent); 137 struct kempld_platform_data *pdata = dev_get_platdata(pld->dev); 138 struct kempld_gpio_data *gpio; 139 struct gpio_chip *chip; 140 int ret; 141 142 if (pld->info.spec_major < 2) { 143 dev_err(dev, 144 "Driver only supports GPIO devices compatible to PLD spec. rev. 2.0 or higher\n"); 145 return -ENODEV; 146 } 147 148 gpio = devm_kzalloc(dev, sizeof(*gpio), GFP_KERNEL); 149 if (!gpio) 150 return -ENOMEM; 151 152 gpio->pld = pld; 153 154 platform_set_drvdata(pdev, gpio); 155 156 chip = &gpio->chip; 157 chip->label = "gpio-kempld"; 158 chip->owner = THIS_MODULE; 159 chip->parent = dev; 160 chip->can_sleep = true; 161 if (pdata && pdata->gpio_base) 162 chip->base = pdata->gpio_base; 163 else 164 chip->base = -1; 165 chip->direction_input = kempld_gpio_direction_input; 166 chip->direction_output = kempld_gpio_direction_output; 167 chip->get_direction = kempld_gpio_get_direction; 168 chip->get = kempld_gpio_get; 169 chip->set = kempld_gpio_set; 170 chip->ngpio = kempld_gpio_pincount(pld); 171 if (chip->ngpio == 0) { 172 dev_err(dev, "No GPIO pins detected\n"); 173 return -ENODEV; 174 } 175 176 ret = devm_gpiochip_add_data(dev, chip, gpio); 177 if (ret) { 178 dev_err(dev, "Could not register GPIO chip\n"); 179 return ret; 180 } 181 182 dev_info(dev, "GPIO functionality initialized with %d pins\n", 183 chip->ngpio); 184 185 return 0; 186 } 187 188 static struct platform_driver kempld_gpio_driver = { 189 .driver = { 190 .name = "kempld-gpio", 191 }, 192 .probe = kempld_gpio_probe, 193 }; 194 195 module_platform_driver(kempld_gpio_driver); 196 197 MODULE_DESCRIPTION("KEM PLD GPIO Driver"); 198 MODULE_AUTHOR("Michael Brunner <michael.brunner@kontron.com>"); 199 MODULE_LICENSE("GPL"); 200 MODULE_ALIAS("platform:kempld-gpio"); 201