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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 as published
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* by the Free Software Foundation.
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* Copyright (C) 2012 John Crispin <blogic@openwrt.org>
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/types.h>
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#include <linux/platform_device.h>
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#include <linux/mutex.h>
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#include <linux/gpio.h>
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#include <linux/of_gpio.h>
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#include <linux/slab.h>
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#include <lantiq_soc.h>
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* By attaching hardware latches to the EBU it is possible to create output
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* only gpios. This driver configures a special memory address, which when
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* written to outputs 16 bit to the latches.
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#define LTQ_EBU_BUSCON 0x1e7ff /* 16 bit access, slowest timing */
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#define LTQ_EBU_WP 0x80000000 /* write protect bit */
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struct of_mm_gpio_chip mmchip;
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u16 shadow; /* shadow the latches state */
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* ltq_mm_apply() - write the shadow value to the ebu address.
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* @chip: Pointer to our private data structure.
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* Write the shadow value to the EBU to set the gpios. We need to set the
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* global EBU lock to make sure that PCI/MTD dont break.
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static void ltq_mm_apply(struct ltq_mm *chip)
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spin_lock_irqsave(&ebu_lock, flags);
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ltq_ebu_w32(LTQ_EBU_BUSCON, LTQ_EBU_BUSCON1);
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__raw_writew(chip->shadow, chip->mmchip.regs);
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ltq_ebu_w32(LTQ_EBU_BUSCON | LTQ_EBU_WP, LTQ_EBU_BUSCON1);
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spin_unlock_irqrestore(&ebu_lock, flags);
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* ltq_mm_set() - gpio_chip->set - set gpios.
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* @gc: Pointer to gpio_chip device structure.
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* @gpio: GPIO signal number.
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* @val: Value to be written to specified signal.
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* Set the shadow value and call ltq_mm_apply.
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static void ltq_mm_set(struct gpio_chip *gc, unsigned offset, int value)
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struct of_mm_gpio_chip *mm_gc = to_of_mm_gpio_chip(gc);
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container_of(mm_gc, struct ltq_mm, mmchip);
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chip->shadow |= (1 << offset);
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chip->shadow &= ~(1 << offset);
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* ltq_mm_dir_out() - gpio_chip->dir_out - set gpio direction.
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* @gc: Pointer to gpio_chip device structure.
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* @gpio: GPIO signal number.
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* @val: Value to be written to specified signal.
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* Same as ltq_mm_set, always returns 0.
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static int ltq_mm_dir_out(struct gpio_chip *gc, unsigned offset, int value)
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ltq_mm_set(gc, offset, value);
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* ltq_mm_save_regs() - Set initial values of GPIO pins
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* @mm_gc: pointer to memory mapped GPIO chip structure
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static void ltq_mm_save_regs(struct of_mm_gpio_chip *mm_gc)
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container_of(mm_gc, struct ltq_mm, mmchip);
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/* tell the ebu controller which memory address we will be using */
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ltq_ebu_w32(CPHYSADDR(chip->mmchip.regs) | 0x1, LTQ_EBU_ADDRSEL1);
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static int ltq_mm_probe(struct platform_device *pdev)
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struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
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const __be32 *shadow;
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dev_err(&pdev->dev, "failed to get memory resource\n");
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chip = kzalloc(sizeof(*chip), GFP_KERNEL);
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chip->mmchip.gc.ngpio = 16;
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chip->mmchip.gc.label = "gpio-mm-ltq";
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chip->mmchip.gc.direction_output = ltq_mm_dir_out;
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chip->mmchip.gc.set = ltq_mm_set;
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chip->mmchip.save_regs = ltq_mm_save_regs;
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/* store the shadow value if one was passed by the devicetree */
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shadow = of_get_property(pdev->dev.of_node, "lantiq,shadow", NULL);
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chip->shadow = be32_to_cpu(*shadow);
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ret = of_mm_gpiochip_add(pdev->dev.of_node, &chip->mmchip);
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static const struct of_device_id ltq_mm_match[] = {
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{ .compatible = "lantiq,gpio-mm" },
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MODULE_DEVICE_TABLE(of, ltq_mm_match);
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static struct platform_driver ltq_mm_driver = {
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.probe = ltq_mm_probe,
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.name = "gpio-mm-ltq",
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.owner = THIS_MODULE,
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.of_match_table = ltq_mm_match,
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static int __init ltq_mm_init(void)
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return platform_driver_register(<q_mm_driver);
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subsys_initcall(ltq_mm_init);