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159 lines
3.9 KiB
159 lines
3.9 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* |
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* Copyright (C) 2012 John Crispin <[email protected]> |
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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 don't 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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