diff options
Diffstat (limited to 'drivers/gpio/gpio-exar.c')
| -rw-r--r-- | drivers/gpio/gpio-exar.c | 200 |
1 files changed, 200 insertions, 0 deletions
diff --git a/drivers/gpio/gpio-exar.c b/drivers/gpio/gpio-exar.c new file mode 100644 index 000000000000..05c8946d6446 --- /dev/null +++ b/drivers/gpio/gpio-exar.c @@ -0,0 +1,200 @@ +/* + * GPIO driver for Exar XR17V35X chip + * + * Copyright (C) 2015 Sudip Mukherjee <sudip.mukherjee@codethink.co.uk> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ +#include <linux/bitops.h> +#include <linux/device.h> +#include <linux/gpio/driver.h> +#include <linux/init.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/pci.h> +#include <linux/platform_device.h> + +#define EXAR_OFFSET_MPIOLVL_LO 0x90 +#define EXAR_OFFSET_MPIOSEL_LO 0x93 +#define EXAR_OFFSET_MPIOLVL_HI 0x96 +#define EXAR_OFFSET_MPIOSEL_HI 0x99 + +#define DRIVER_NAME "gpio_exar" + +static DEFINE_IDA(ida_index); + +struct exar_gpio_chip { + struct gpio_chip gpio_chip; + struct mutex lock; + int index; + void __iomem *regs; + char name[20]; +}; + +static void exar_update(struct gpio_chip *chip, unsigned int reg, int val, + unsigned int offset) +{ + struct exar_gpio_chip *exar_gpio = gpiochip_get_data(chip); + int temp; + + mutex_lock(&exar_gpio->lock); + temp = readb(exar_gpio->regs + reg); + temp &= ~BIT(offset); + if (val) + temp |= BIT(offset); + writeb(temp, exar_gpio->regs + reg); + mutex_unlock(&exar_gpio->lock); +} + +static int exar_set_direction(struct gpio_chip *chip, int direction, + unsigned int offset) +{ + unsigned int bank = offset / 8; + unsigned int addr; + + addr = bank ? EXAR_OFFSET_MPIOSEL_HI : EXAR_OFFSET_MPIOSEL_LO; + exar_update(chip, addr, direction, offset % 8); + return 0; +} + +static int exar_direction_output(struct gpio_chip *chip, unsigned int offset, + int value) +{ + return exar_set_direction(chip, 0, offset); +} + +static int exar_direction_input(struct gpio_chip *chip, unsigned int offset) +{ + return exar_set_direction(chip, 1, offset); +} + +static int exar_get(struct gpio_chip *chip, unsigned int reg) +{ + struct exar_gpio_chip *exar_gpio = gpiochip_get_data(chip); + int value; + + mutex_lock(&exar_gpio->lock); + value = readb(exar_gpio->regs + reg); + mutex_unlock(&exar_gpio->lock); + + return !!value; +} + +static int exar_get_direction(struct gpio_chip *chip, unsigned int offset) +{ + unsigned int bank = offset / 8; + unsigned int addr; + int val; + + addr = bank ? EXAR_OFFSET_MPIOSEL_HI : EXAR_OFFSET_MPIOSEL_LO; + val = exar_get(chip, addr) >> (offset % 8); + + return !!val; +} + +static int exar_get_value(struct gpio_chip *chip, unsigned int offset) +{ + unsigned int bank = offset / 8; + unsigned int addr; + int val; + + addr = bank ? EXAR_OFFSET_MPIOLVL_LO : EXAR_OFFSET_MPIOLVL_HI; + val = exar_get(chip, addr) >> (offset % 8); + + return !!val; +} + +static void exar_set_value(struct gpio_chip *chip, unsigned int offset, + int value) +{ + unsigned int bank = offset / 8; + unsigned int addr; + + addr = bank ? EXAR_OFFSET_MPIOLVL_HI : EXAR_OFFSET_MPIOLVL_LO; + exar_update(chip, addr, value, offset % 8); +} + +static int gpio_exar_probe(struct platform_device *pdev) +{ + struct pci_dev *pcidev = platform_get_drvdata(pdev); + struct exar_gpio_chip *exar_gpio; + void __iomem *p; + int index, ret; + + if (pcidev->vendor != PCI_VENDOR_ID_EXAR) + return -ENODEV; + + /* + * Map the pci device to get the register addresses. + * We will need to read and write those registers to control + * the GPIO pins. + * Using managed functions will save us from unmaping on exit. + * As the device is enabled using managed functions by the + * UART driver we can also use managed functions here. + */ + p = pcim_iomap(pcidev, 0, 0); + if (!p) + return -ENOMEM; + + exar_gpio = devm_kzalloc(&pcidev->dev, sizeof(*exar_gpio), GFP_KERNEL); + if (!exar_gpio) + return -ENOMEM; + + mutex_init(&exar_gpio->lock); + + index = ida_simple_get(&ida_index, 0, 0, GFP_KERNEL); + + sprintf(exar_gpio->name, "exar_gpio%d", index); + exar_gpio->gpio_chip.label = exar_gpio->name; + exar_gpio->gpio_chip.parent = &pcidev->dev; + exar_gpio->gpio_chip.direction_output = exar_direction_output; + exar_gpio->gpio_chip.direction_input = exar_direction_input; + exar_gpio->gpio_chip.get_direction = exar_get_direction; + exar_gpio->gpio_chip.get = exar_get_value; + exar_gpio->gpio_chip.set = exar_set_value; + exar_gpio->gpio_chip.base = -1; + exar_gpio->gpio_chip.ngpio = 16; + exar_gpio->regs = p; + exar_gpio->index = index; + + ret = devm_gpiochip_add_data(&pcidev->dev, + &exar_gpio->gpio_chip, exar_gpio); + if (ret) + goto err_destroy; + + platform_set_drvdata(pdev, exar_gpio); + + return 0; + +err_destroy: + ida_simple_remove(&ida_index, index); + mutex_destroy(&exar_gpio->lock); + return ret; +} + +static int gpio_exar_remove(struct platform_device *pdev) +{ + struct exar_gpio_chip *exar_gpio = platform_get_drvdata(pdev); + + ida_simple_remove(&ida_index, exar_gpio->index); + mutex_destroy(&exar_gpio->lock); + + return 0; +} + +static struct platform_driver gpio_exar_driver = { + .probe = gpio_exar_probe, + .remove = gpio_exar_remove, + .driver = { + .name = DRIVER_NAME, + }, +}; + +module_platform_driver(gpio_exar_driver); + +MODULE_ALIAS("platform:" DRIVER_NAME); +MODULE_DESCRIPTION("Exar GPIO driver"); +MODULE_AUTHOR("Sudip Mukherjee <sudip.mukherjee@codethink.co.uk>"); +MODULE_LICENSE("GPL"); |