diff options
Diffstat (limited to 'drivers/gpio/gpio-zevio.c')
| -rw-r--r-- | drivers/gpio/gpio-zevio.c | 220 |
1 files changed, 220 insertions, 0 deletions
diff --git a/drivers/gpio/gpio-zevio.c b/drivers/gpio/gpio-zevio.c new file mode 100644 index 000000000000..9bf5034b6cdb --- /dev/null +++ b/drivers/gpio/gpio-zevio.c @@ -0,0 +1,220 @@ +/* + * GPIO controller in LSI ZEVIO SoCs. + * + * Author: Fabian Vogt <fabian@ritter-vogt.de> + * + * 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/spinlock.h> +#include <linux/errno.h> +#include <linux/module.h> +#include <linux/bitops.h> +#include <linux/io.h> +#include <linux/of_device.h> +#include <linux/of_gpio.h> +#include <linux/slab.h> +#include <linux/gpio.h> + +/* + * Memory layout: + * This chip has four gpio sections, each controls 8 GPIOs. + * Bit 0 in section 0 is GPIO 0, bit 2 in section 1 is GPIO 10. + * Disclaimer: Reverse engineered! + * For more information refer to: + * http://hackspire.unsads.com/wiki/index.php/Memory-mapped_I/O_ports#90000000_-_General_Purpose_I.2FO_.28GPIO.29 + * + * 0x00-0x3F: Section 0 + * +0x00: Masked interrupt status (read-only) + * +0x04: R: Interrupt status W: Reset interrupt status + * +0x08: R: Interrupt mask W: Mask interrupt + * +0x0C: W: Unmask interrupt (write-only) + * +0x10: Direction: I/O=1/0 + * +0x14: Output + * +0x18: Input (read-only) + * +0x20: R: Level interrupt W: Set as level interrupt + * 0x40-0x7F: Section 1 + * 0x80-0xBF: Section 2 + * 0xC0-0xFF: Section 3 + */ + +#define ZEVIO_GPIO_SECTION_SIZE 0x40 + +/* Offsets to various registers */ +#define ZEVIO_GPIO_INT_MASKED_STATUS 0x00 +#define ZEVIO_GPIO_INT_STATUS 0x04 +#define ZEVIO_GPIO_INT_UNMASK 0x08 +#define ZEVIO_GPIO_INT_MASK 0x0C +#define ZEVIO_GPIO_DIRECTION 0x10 +#define ZEVIO_GPIO_OUTPUT 0x14 +#define ZEVIO_GPIO_INPUT 0x18 +#define ZEVIO_GPIO_INT_STICKY 0x20 + +#define to_zevio_gpio(chip) container_of(to_of_mm_gpio_chip(chip), \ + struct zevio_gpio, chip) + +/* Bit number of GPIO in its section */ +#define ZEVIO_GPIO_BIT(gpio) (gpio&7) + +struct zevio_gpio { + spinlock_t lock; + struct of_mm_gpio_chip chip; +}; + +static inline u32 zevio_gpio_port_get(struct zevio_gpio *c, unsigned pin, + unsigned port_offset) +{ + unsigned section_offset = ((pin >> 3) & 3)*ZEVIO_GPIO_SECTION_SIZE; + return readl(IOMEM(c->chip.regs + section_offset + port_offset)); +} + +static inline void zevio_gpio_port_set(struct zevio_gpio *c, unsigned pin, + unsigned port_offset, u32 val) +{ + unsigned section_offset = ((pin >> 3) & 3)*ZEVIO_GPIO_SECTION_SIZE; + writel(val, IOMEM(c->chip.regs + section_offset + port_offset)); +} + +/* Functions for struct gpio_chip */ +static int zevio_gpio_get(struct gpio_chip *chip, unsigned pin) +{ + struct zevio_gpio *controller = to_zevio_gpio(chip); + + /* Only reading allowed, so no spinlock needed */ + u32 val = zevio_gpio_port_get(controller, pin, ZEVIO_GPIO_INPUT); + + return (val >> ZEVIO_GPIO_BIT(pin)) & 0x1; +} + +static void zevio_gpio_set(struct gpio_chip *chip, unsigned pin, int value) +{ + struct zevio_gpio *controller = to_zevio_gpio(chip); + u32 val; + + spin_lock(&controller->lock); + val = zevio_gpio_port_get(controller, pin, ZEVIO_GPIO_OUTPUT); + if (value) + val |= BIT(ZEVIO_GPIO_BIT(pin)); + else + val &= ~BIT(ZEVIO_GPIO_BIT(pin)); + + zevio_gpio_port_set(controller, pin, ZEVIO_GPIO_OUTPUT, val); + spin_unlock(&controller->lock); +} + +static int zevio_gpio_direction_input(struct gpio_chip *chip, unsigned pin) +{ + struct zevio_gpio *controller = to_zevio_gpio(chip); + u32 val; + + spin_lock(&controller->lock); + + val = zevio_gpio_port_get(controller, pin, ZEVIO_GPIO_DIRECTION); + val |= BIT(ZEVIO_GPIO_BIT(pin)); + zevio_gpio_port_set(controller, pin, ZEVIO_GPIO_DIRECTION, val); + + spin_unlock(&controller->lock); + + return 0; +} + +static int zevio_gpio_direction_output(struct gpio_chip *chip, + unsigned pin, int value) +{ + struct zevio_gpio *controller = to_zevio_gpio(chip); + u32 val; + + spin_lock(&controller->lock); + val = zevio_gpio_port_get(controller, pin, ZEVIO_GPIO_OUTPUT); + if (value) + val |= BIT(ZEVIO_GPIO_BIT(pin)); + else + val &= ~BIT(ZEVIO_GPIO_BIT(pin)); + + zevio_gpio_port_set(controller, pin, ZEVIO_GPIO_OUTPUT, val); + val = zevio_gpio_port_get(controller, pin, ZEVIO_GPIO_DIRECTION); + val &= ~BIT(ZEVIO_GPIO_BIT(pin)); + zevio_gpio_port_set(controller, pin, ZEVIO_GPIO_DIRECTION, val); + + spin_unlock(&controller->lock); + + return 0; +} + +static int zevio_gpio_to_irq(struct gpio_chip *chip, unsigned pin) +{ + /* + * TODO: Implement IRQs. + * Not implemented yet due to weird lockups + */ + + return -ENXIO; +} + +static struct gpio_chip zevio_gpio_chip = { + .direction_input = zevio_gpio_direction_input, + .direction_output = zevio_gpio_direction_output, + .set = zevio_gpio_set, + .get = zevio_gpio_get, + .to_irq = zevio_gpio_to_irq, + .base = 0, + .owner = THIS_MODULE, + .ngpio = 32, + .of_gpio_n_cells = 2, +}; + +/* Initialization */ +static int zevio_gpio_probe(struct platform_device *pdev) +{ + struct zevio_gpio *controller; + int status, i; + + controller = devm_kzalloc(&pdev->dev, sizeof(*controller), GFP_KERNEL); + if (!controller) { + dev_err(&pdev->dev, "not enough free memory\n"); + return -ENOMEM; + } + + /* Copy our reference */ + controller->chip.gc = zevio_gpio_chip; + controller->chip.gc.dev = &pdev->dev; + + status = of_mm_gpiochip_add(pdev->dev.of_node, &(controller->chip)); + if (status) { + dev_err(&pdev->dev, "failed to add gpiochip: %d\n", status); + return status; + } + + spin_lock_init(&controller->lock); + + /* Disable interrupts, they only cause errors */ + for (i = 0; i < controller->chip.gc.ngpio; i += 8) + zevio_gpio_port_set(controller, i, ZEVIO_GPIO_INT_MASK, 0xFF); + + dev_dbg(controller->chip.gc.dev, "ZEVIO GPIO controller set up!\n"); + + return 0; +} + +static struct of_device_id zevio_gpio_of_match[] = { + { .compatible = "lsi,zevio-gpio", }, + { }, +}; + +MODULE_DEVICE_TABLE(of, zevio_gpio_of_match); + +static struct platform_driver zevio_gpio_driver = { + .driver = { + .name = "gpio-zevio", + .owner = THIS_MODULE, + .of_match_table = of_match_ptr(zevio_gpio_of_match), + }, + .probe = zevio_gpio_probe, +}; +module_platform_driver(zevio_gpio_driver); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Fabian Vogt <fabian@ritter-vogt.de>"); +MODULE_DESCRIPTION("LSI ZEVIO SoC GPIO driver"); |