drivers/gpio/gpio-kempld.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * Kontron PLD GPIO driver
0004  *
0005  * Copyright (c) 2010-2013 Kontron Europe GmbH
0006  * Author: Michael Brunner <michael.brunner@kontron.com>
0007  */
0008
0009 #include <linux/init.h>
0010 #include <linux/kernel.h>
0011 #include <linux/module.h>
0012 #include <linux/bitops.h>
0013 #include <linux/errno.h>
0014 #include <linux/platform_device.h>
0015 #include <linux/gpio/driver.h>
0016 #include <linux/mfd/kempld.h>
0017
0018 #define KEMPLD_GPIO_MAX_NUM     16
0019 #define KEMPLD_GPIO_MASK(x)     (BIT((x) % 8))
0020 #define KEMPLD_GPIO_DIR_NUM(x)      (0x40 + (x) / 8)
0021 #define KEMPLD_GPIO_LVL_NUM(x)      (0x42 + (x) / 8)
0022 #define KEMPLD_GPIO_EVT_LVL_EDGE    0x46
0023 #define KEMPLD_GPIO_IEN         0x4A
0024
0025 struct kempld_gpio_data {
0026     struct gpio_chip        chip;
0027     struct kempld_device_data   *pld;
0028 };
0029
0030 /*
0031  * Set or clear GPIO bit
0032  * kempld_get_mutex must be called prior to calling this function.
0033  */
0034 static void kempld_gpio_bitop(struct kempld_device_data *pld,
0035                   u8 reg, u8 bit, u8 val)
0036 {
0037     u8 status;
0038
0039     status = kempld_read8(pld, reg);
0040     if (val)
0041         status |= KEMPLD_GPIO_MASK(bit);
0042     else
0043         status &= ~KEMPLD_GPIO_MASK(bit);
0044     kempld_write8(pld, reg, status);
0045 }
0046
0047 static int kempld_gpio_get_bit(struct kempld_device_data *pld, u8 reg, u8 bit)
0048 {
0049     u8 status;
0050
0051     kempld_get_mutex(pld);
0052     status = kempld_read8(pld, reg);
0053     kempld_release_mutex(pld);
0054
0055     return !!(status & KEMPLD_GPIO_MASK(bit));
0056 }
0057
0058 static int kempld_gpio_get(struct gpio_chip *chip, unsigned offset)
0059 {
0060     struct kempld_gpio_data *gpio = gpiochip_get_data(chip);
0061     struct kempld_device_data *pld = gpio->pld;
0062
0063     return !!kempld_gpio_get_bit(pld, KEMPLD_GPIO_LVL_NUM(offset), offset);
0064 }
0065
0066 static void kempld_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
0067 {
0068     struct kempld_gpio_data *gpio = gpiochip_get_data(chip);
0069     struct kempld_device_data *pld = gpio->pld;
0070
0071     kempld_get_mutex(pld);
0072     kempld_gpio_bitop(pld, KEMPLD_GPIO_LVL_NUM(offset), offset, value);
0073     kempld_release_mutex(pld);
0074 }
0075
0076 static int kempld_gpio_direction_input(struct gpio_chip *chip, unsigned offset)
0077 {
0078     struct kempld_gpio_data *gpio = gpiochip_get_data(chip);
0079     struct kempld_device_data *pld = gpio->pld;
0080
0081     kempld_get_mutex(pld);
0082     kempld_gpio_bitop(pld, KEMPLD_GPIO_DIR_NUM(offset), offset, 0);
0083     kempld_release_mutex(pld);
0084
0085     return 0;
0086 }
0087
0088 static int kempld_gpio_direction_output(struct gpio_chip *chip, unsigned offset,
0089                     int value)
0090 {
0091     struct kempld_gpio_data *gpio = gpiochip_get_data(chip);
0092     struct kempld_device_data *pld = gpio->pld;
0093
0094     kempld_get_mutex(pld);
0095     kempld_gpio_bitop(pld, KEMPLD_GPIO_LVL_NUM(offset), offset, value);
0096     kempld_gpio_bitop(pld, KEMPLD_GPIO_DIR_NUM(offset), offset, 1);
0097     kempld_release_mutex(pld);
0098
0099     return 0;
0100 }
0101
0102 static int kempld_gpio_get_direction(struct gpio_chip *chip, unsigned offset)
0103 {
0104     struct kempld_gpio_data *gpio = gpiochip_get_data(chip);
0105     struct kempld_device_data *pld = gpio->pld;
0106
0107     if (kempld_gpio_get_bit(pld, KEMPLD_GPIO_DIR_NUM(offset), offset))
0108         return GPIO_LINE_DIRECTION_OUT;
0109
0110     return GPIO_LINE_DIRECTION_IN;
0111 }
0112
0113 static int kempld_gpio_pincount(struct kempld_device_data *pld)
0114 {
0115     u16 evt, evt_back;
0116
0117     kempld_get_mutex(pld);
0118
0119     /* Backup event register as it might be already initialized */
0120     evt_back = kempld_read16(pld, KEMPLD_GPIO_EVT_LVL_EDGE);
0121     /* Clear event register */
0122     kempld_write16(pld, KEMPLD_GPIO_EVT_LVL_EDGE, 0x0000);
0123     /* Read back event register */
0124     evt = kempld_read16(pld, KEMPLD_GPIO_EVT_LVL_EDGE);
0125     /* Restore event register */
0126     kempld_write16(pld, KEMPLD_GPIO_EVT_LVL_EDGE, evt_back);
0127
0128     kempld_release_mutex(pld);
0129
0130     return evt ? __ffs(evt) : 16;
0131 }
0132
0133 static int kempld_gpio_probe(struct platform_device *pdev)
0134 {
0135     struct device *dev = &pdev->dev;
0136     struct kempld_device_data *pld = dev_get_drvdata(dev->parent);
0137     struct kempld_platform_data *pdata = dev_get_platdata(pld->dev);
0138     struct kempld_gpio_data *gpio;
0139     struct gpio_chip *chip;
0140     int ret;
0141
0142     if (pld->info.spec_major < 2) {
0143         dev_err(dev,
0144             "Driver only supports GPIO devices compatible to PLD spec. rev. 2.0 or higher\n");
0145         return -ENODEV;
0146     }
0147
0148     gpio = devm_kzalloc(dev, sizeof(*gpio), GFP_KERNEL);
0149     if (!gpio)
0150         return -ENOMEM;
0151
0152     gpio->pld = pld;
0153
0154     platform_set_drvdata(pdev, gpio);
0155
0156     chip = &gpio->chip;
0157     chip->label = "gpio-kempld";
0158     chip->owner = THIS_MODULE;
0159     chip->parent = dev;
0160     chip->can_sleep = true;
0161     if (pdata && pdata->gpio_base)
0162         chip->base = pdata->gpio_base;
0163     else
0164         chip->base = -1;
0165     chip->direction_input = kempld_gpio_direction_input;
0166     chip->direction_output = kempld_gpio_direction_output;
0167     chip->get_direction = kempld_gpio_get_direction;
0168     chip->get = kempld_gpio_get;
0169     chip->set = kempld_gpio_set;
0170     chip->ngpio = kempld_gpio_pincount(pld);
0171     if (chip->ngpio == 0) {
0172         dev_err(dev, "No GPIO pins detected\n");
0173         return -ENODEV;
0174     }
0175
0176     ret = devm_gpiochip_add_data(dev, chip, gpio);
0177     if (ret) {
0178         dev_err(dev, "Could not register GPIO chip\n");
0179         return ret;
0180     }
0181
0182     dev_info(dev, "GPIO functionality initialized with %d pins\n",
0183          chip->ngpio);
0184
0185     return 0;
0186 }
0187
0188 static struct platform_driver kempld_gpio_driver = {
0189     .driver = {
0190         .name = "kempld-gpio",
0191     },
0192     .probe      = kempld_gpio_probe,
0193 };
0194
0195 module_platform_driver(kempld_gpio_driver);
0196
0197 MODULE_DESCRIPTION("KEM PLD GPIO Driver");
0198 MODULE_AUTHOR("Michael Brunner <michael.brunner@kontron.com>");
0199 MODULE_LICENSE("GPL");
0200 MODULE_ALIAS("platform:kempld-gpio");