diff options
Diffstat (limited to '')
| -rw-r--r-- | drivers/gpio/gpio-kempld.c | 205 |
1 files changed, 205 insertions, 0 deletions
diff --git a/drivers/gpio/gpio-kempld.c b/drivers/gpio/gpio-kempld.c new file mode 100644 index 000000000..7bb96f48e --- /dev/null +++ b/drivers/gpio/gpio-kempld.c @@ -0,0 +1,205 @@ +/* + * Kontron PLD GPIO driver + * + * Copyright (c) 2010-2013 Kontron Europe GmbH + * Author: Michael Brunner <michael.brunner@kontron.com> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License 2 as published + * by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + */ + +#include <linux/init.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/bitops.h> +#include <linux/errno.h> +#include <linux/platform_device.h> +#include <linux/gpio/driver.h> +#include <linux/mfd/kempld.h> + +#define KEMPLD_GPIO_MAX_NUM 16 +#define KEMPLD_GPIO_MASK(x) (BIT((x) % 8)) +#define KEMPLD_GPIO_DIR_NUM(x) (0x40 + (x) / 8) +#define KEMPLD_GPIO_LVL_NUM(x) (0x42 + (x) / 8) +#define KEMPLD_GPIO_EVT_LVL_EDGE 0x46 +#define KEMPLD_GPIO_IEN 0x4A + +struct kempld_gpio_data { + struct gpio_chip chip; + struct kempld_device_data *pld; +}; + +/* + * Set or clear GPIO bit + * kempld_get_mutex must be called prior to calling this function. + */ +static void kempld_gpio_bitop(struct kempld_device_data *pld, + u8 reg, u8 bit, u8 val) +{ + u8 status; + + status = kempld_read8(pld, reg); + if (val) + status |= KEMPLD_GPIO_MASK(bit); + else + status &= ~KEMPLD_GPIO_MASK(bit); + kempld_write8(pld, reg, status); +} + +static int kempld_gpio_get_bit(struct kempld_device_data *pld, u8 reg, u8 bit) +{ + u8 status; + + kempld_get_mutex(pld); + status = kempld_read8(pld, reg); + kempld_release_mutex(pld); + + return !!(status & KEMPLD_GPIO_MASK(bit)); +} + +static int kempld_gpio_get(struct gpio_chip *chip, unsigned offset) +{ + struct kempld_gpio_data *gpio = gpiochip_get_data(chip); + struct kempld_device_data *pld = gpio->pld; + + return !!kempld_gpio_get_bit(pld, KEMPLD_GPIO_LVL_NUM(offset), offset); +} + +static void kempld_gpio_set(struct gpio_chip *chip, unsigned offset, int value) +{ + struct kempld_gpio_data *gpio = gpiochip_get_data(chip); + struct kempld_device_data *pld = gpio->pld; + + kempld_get_mutex(pld); + kempld_gpio_bitop(pld, KEMPLD_GPIO_LVL_NUM(offset), offset, value); + kempld_release_mutex(pld); +} + +static int kempld_gpio_direction_input(struct gpio_chip *chip, unsigned offset) +{ + struct kempld_gpio_data *gpio = gpiochip_get_data(chip); + struct kempld_device_data *pld = gpio->pld; + + kempld_get_mutex(pld); + kempld_gpio_bitop(pld, KEMPLD_GPIO_DIR_NUM(offset), offset, 0); + kempld_release_mutex(pld); + + return 0; +} + +static int kempld_gpio_direction_output(struct gpio_chip *chip, unsigned offset, + int value) +{ + struct kempld_gpio_data *gpio = gpiochip_get_data(chip); + struct kempld_device_data *pld = gpio->pld; + + kempld_get_mutex(pld); + kempld_gpio_bitop(pld, KEMPLD_GPIO_LVL_NUM(offset), offset, value); + kempld_gpio_bitop(pld, KEMPLD_GPIO_DIR_NUM(offset), offset, 1); + kempld_release_mutex(pld); + + return 0; +} + +static int kempld_gpio_get_direction(struct gpio_chip *chip, unsigned offset) +{ + struct kempld_gpio_data *gpio = gpiochip_get_data(chip); + struct kempld_device_data *pld = gpio->pld; + + return !kempld_gpio_get_bit(pld, KEMPLD_GPIO_DIR_NUM(offset), offset); +} + +static int kempld_gpio_pincount(struct kempld_device_data *pld) +{ + u16 evt, evt_back; + + kempld_get_mutex(pld); + + /* Backup event register as it might be already initialized */ + evt_back = kempld_read16(pld, KEMPLD_GPIO_EVT_LVL_EDGE); + /* Clear event register */ + kempld_write16(pld, KEMPLD_GPIO_EVT_LVL_EDGE, 0x0000); + /* Read back event register */ + evt = kempld_read16(pld, KEMPLD_GPIO_EVT_LVL_EDGE); + /* Restore event register */ + kempld_write16(pld, KEMPLD_GPIO_EVT_LVL_EDGE, evt_back); + + kempld_release_mutex(pld); + + return evt ? __ffs(evt) : 16; +} + +static int kempld_gpio_probe(struct platform_device *pdev) +{ + struct device *dev = &pdev->dev; + struct kempld_device_data *pld = dev_get_drvdata(dev->parent); + struct kempld_platform_data *pdata = dev_get_platdata(pld->dev); + struct kempld_gpio_data *gpio; + struct gpio_chip *chip; + int ret; + + if (pld->info.spec_major < 2) { + dev_err(dev, + "Driver only supports GPIO devices compatible to PLD spec. rev. 2.0 or higher\n"); + return -ENODEV; + } + + gpio = devm_kzalloc(dev, sizeof(*gpio), GFP_KERNEL); + if (!gpio) + return -ENOMEM; + + gpio->pld = pld; + + platform_set_drvdata(pdev, gpio); + + chip = &gpio->chip; + chip->label = "gpio-kempld"; + chip->owner = THIS_MODULE; + chip->parent = dev; + chip->can_sleep = true; + if (pdata && pdata->gpio_base) + chip->base = pdata->gpio_base; + else + chip->base = -1; + chip->direction_input = kempld_gpio_direction_input; + chip->direction_output = kempld_gpio_direction_output; + chip->get_direction = kempld_gpio_get_direction; + chip->get = kempld_gpio_get; + chip->set = kempld_gpio_set; + chip->ngpio = kempld_gpio_pincount(pld); + if (chip->ngpio == 0) { + dev_err(dev, "No GPIO pins detected\n"); + return -ENODEV; + } + + ret = devm_gpiochip_add_data(dev, chip, gpio); + if (ret) { + dev_err(dev, "Could not register GPIO chip\n"); + return ret; + } + + dev_info(dev, "GPIO functionality initialized with %d pins\n", + chip->ngpio); + + return 0; +} + +static struct platform_driver kempld_gpio_driver = { + .driver = { + .name = "kempld-gpio", + }, + .probe = kempld_gpio_probe, +}; + +module_platform_driver(kempld_gpio_driver); + +MODULE_DESCRIPTION("KEM PLD GPIO Driver"); +MODULE_AUTHOR("Michael Brunner <michael.brunner@kontron.com>"); +MODULE_LICENSE("GPL"); +MODULE_ALIAS("platform:kempld-gpio"); |