162 lines
4 KiB
C
162 lines
4 KiB
C
/*
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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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*
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* Copyright (C) 2012 John Crispin <john@phrozen.org>
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*/
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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/driver.h>
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#include <linux/of.h>
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#include <linux/of_gpio.h>
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#include <linux/io.h>
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#include <linux/slab.h>
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#include <lantiq_soc.h>
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/*
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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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*/
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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 ltq_mm {
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struct of_mm_gpio_chip mmchip;
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u16 shadow; /* shadow the latches state */
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};
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/**
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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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*
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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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*/
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static void ltq_mm_apply(struct ltq_mm *chip)
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{
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unsigned long flags;
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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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}
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/**
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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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*
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* Set the shadow value and call ltq_mm_apply.
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*/
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static void ltq_mm_set(struct gpio_chip *gc, unsigned offset, int value)
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{
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struct ltq_mm *chip = gpiochip_get_data(gc);
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if (value)
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chip->shadow |= (1 << offset);
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else
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chip->shadow &= ~(1 << offset);
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ltq_mm_apply(chip);
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}
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/**
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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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*
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* Same as ltq_mm_set, always returns 0.
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*/
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static int ltq_mm_dir_out(struct gpio_chip *gc, unsigned offset, int value)
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{
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ltq_mm_set(gc, offset, value);
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return 0;
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}
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/**
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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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*/
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static void ltq_mm_save_regs(struct of_mm_gpio_chip *mm_gc)
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{
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struct ltq_mm *chip =
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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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ltq_mm_apply(chip);
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}
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static int ltq_mm_probe(struct platform_device *pdev)
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{
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struct ltq_mm *chip;
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u32 shadow;
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chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL);
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if (!chip)
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return -ENOMEM;
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platform_set_drvdata(pdev, chip);
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chip->mmchip.gc.ngpio = 16;
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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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if (!of_property_read_u32(pdev->dev.of_node, "lantiq,shadow", &shadow))
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chip->shadow = shadow;
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return of_mm_gpiochip_add_data(pdev->dev.of_node, &chip->mmchip, chip);
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}
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static int ltq_mm_remove(struct platform_device *pdev)
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{
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struct ltq_mm *chip = platform_get_drvdata(pdev);
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of_mm_gpiochip_remove(&chip->mmchip);
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return 0;
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}
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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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{},
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};
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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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.remove = ltq_mm_remove,
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.driver = {
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.name = "gpio-mm-ltq",
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.of_match_table = ltq_mm_match,
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},
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};
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static int __init ltq_mm_init(void)
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{
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return platform_driver_register(<q_mm_driver);
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}
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subsys_initcall(ltq_mm_init);
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static void __exit ltq_mm_exit(void)
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{
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platform_driver_unregister(<q_mm_driver);
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}
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module_exit(ltq_mm_exit);
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