diff options
Diffstat (limited to 'drivers/gpio/gpio-mm-lantiq.c')
| -rw-r--r-- | drivers/gpio/gpio-mm-lantiq.c | 158 |
1 files changed, 158 insertions, 0 deletions
diff --git a/drivers/gpio/gpio-mm-lantiq.c b/drivers/gpio/gpio-mm-lantiq.c new file mode 100644 index 0000000..2983dfb --- /dev/null +++ b/drivers/gpio/gpio-mm-lantiq.c @@ -0,0 +1,158 @@ +/* + * 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. + * + * Copyright (C) 2012 John Crispin <blogic@openwrt.org> + */ + +#include <linux/init.h> +#include <linux/module.h> +#include <linux/types.h> +#include <linux/platform_device.h> +#include <linux/mutex.h> +#include <linux/gpio.h> +#include <linux/of.h> +#include <linux/of_gpio.h> +#include <linux/io.h> +#include <linux/slab.h> + +#include <lantiq_soc.h> + +/* + * By attaching hardware latches to the EBU it is possible to create output + * only gpios. This driver configures a special memory address, which when + * written to outputs 16 bit to the latches. + */ + +#define LTQ_EBU_BUSCON 0x1e7ff /* 16 bit access, slowest timing */ +#define LTQ_EBU_WP 0x80000000 /* write protect bit */ + +struct ltq_mm { + struct of_mm_gpio_chip mmchip; + u16 shadow; /* shadow the latches state */ +}; + +/** + * ltq_mm_apply() - write the shadow value to the ebu address. + * @chip: Pointer to our private data structure. + * + * Write the shadow value to the EBU to set the gpios. We need to set the + * global EBU lock to make sure that PCI/MTD dont break. + */ +static void ltq_mm_apply(struct ltq_mm *chip) +{ + unsigned long flags; + + spin_lock_irqsave(&ebu_lock, flags); + ltq_ebu_w32(LTQ_EBU_BUSCON, LTQ_EBU_BUSCON1); + __raw_writew(chip->shadow, chip->mmchip.regs); + ltq_ebu_w32(LTQ_EBU_BUSCON | LTQ_EBU_WP, LTQ_EBU_BUSCON1); + spin_unlock_irqrestore(&ebu_lock, flags); +} + +/** + * ltq_mm_set() - gpio_chip->set - set gpios. + * @gc: Pointer to gpio_chip device structure. + * @gpio: GPIO signal number. + * @val: Value to be written to specified signal. + * + * Set the shadow value and call ltq_mm_apply. + */ +static void ltq_mm_set(struct gpio_chip *gc, unsigned offset, int value) +{ + struct of_mm_gpio_chip *mm_gc = to_of_mm_gpio_chip(gc); + struct ltq_mm *chip = + container_of(mm_gc, struct ltq_mm, mmchip); + + if (value) + chip->shadow |= (1 << offset); + else + chip->shadow &= ~(1 << offset); + ltq_mm_apply(chip); +} + +/** + * ltq_mm_dir_out() - gpio_chip->dir_out - set gpio direction. + * @gc: Pointer to gpio_chip device structure. + * @gpio: GPIO signal number. + * @val: Value to be written to specified signal. + * + * Same as ltq_mm_set, always returns 0. + */ +static int ltq_mm_dir_out(struct gpio_chip *gc, unsigned offset, int value) +{ + ltq_mm_set(gc, offset, value); + + return 0; +} + +/** + * ltq_mm_save_regs() - Set initial values of GPIO pins + * @mm_gc: pointer to memory mapped GPIO chip structure + */ +static void ltq_mm_save_regs(struct of_mm_gpio_chip *mm_gc) +{ + struct ltq_mm *chip = + container_of(mm_gc, struct ltq_mm, mmchip); + + /* tell the ebu controller which memory address we will be using */ + ltq_ebu_w32(CPHYSADDR(chip->mmchip.regs) | 0x1, LTQ_EBU_ADDRSEL1); + + ltq_mm_apply(chip); +} + +static int ltq_mm_probe(struct platform_device *pdev) +{ + struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0); + struct ltq_mm *chip; + const __be32 *shadow; + int ret = 0; + + if (!res) { + dev_err(&pdev->dev, "failed to get memory resource\n"); + return -ENOENT; + } + + chip = kzalloc(sizeof(*chip), GFP_KERNEL); + if (!chip) + return -ENOMEM; + + chip->mmchip.gc.ngpio = 16; + chip->mmchip.gc.label = "gpio-mm-ltq"; + chip->mmchip.gc.direction_output = ltq_mm_dir_out; + chip->mmchip.gc.set = ltq_mm_set; + chip->mmchip.save_regs = ltq_mm_save_regs; + + /* store the shadow value if one was passed by the devicetree */ + shadow = of_get_property(pdev->dev.of_node, "lantiq,shadow", NULL); + if (shadow) + chip->shadow = be32_to_cpu(*shadow); + + ret = of_mm_gpiochip_add(pdev->dev.of_node, &chip->mmchip); + if (ret) + kfree(chip); + return ret; +} + +static const struct of_device_id ltq_mm_match[] = { + { .compatible = "lantiq,gpio-mm" }, + {}, +}; +MODULE_DEVICE_TABLE(of, ltq_mm_match); + +static struct platform_driver ltq_mm_driver = { + .probe = ltq_mm_probe, + .driver = { + .name = "gpio-mm-ltq", + .owner = THIS_MODULE, + .of_match_table = ltq_mm_match, + }, +}; + +static int __init ltq_mm_init(void) +{ + return platform_driver_register(<q_mm_driver); +} + +subsys_initcall(ltq_mm_init); |