drivers/gpio/gpio-mm-lantiq.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  *
0004  *  Copyright (C) 2012 John Crispin <john@phrozen.org>
0005  */
0006
0007 #include <linux/init.h>
0008 #include <linux/module.h>
0009 #include <linux/types.h>
0010 #include <linux/platform_device.h>
0011 #include <linux/mutex.h>
0012 #include <linux/gpio/driver.h>
0013 #include <linux/of.h>
0014 #include <linux/of_gpio.h>
0015 #include <linux/io.h>
0016 #include <linux/slab.h>
0017
0018 #include <lantiq_soc.h>
0019
0020 /*
0021  * By attaching hardware latches to the EBU it is possible to create output
0022  * only gpios. This driver configures a special memory address, which when
0023  * written to outputs 16 bit to the latches.
0024  */
0025
0026 #define LTQ_EBU_BUSCON  0x1e7ff     /* 16 bit access, slowest timing */
0027 #define LTQ_EBU_WP  0x80000000  /* write protect bit */
0028
0029 struct ltq_mm {
0030     struct of_mm_gpio_chip mmchip;
0031     u16 shadow; /* shadow the latches state */
0032 };
0033
0034 /**
0035  * ltq_mm_apply() - write the shadow value to the ebu address.
0036  * @chip:     Pointer to our private data structure.
0037  *
0038  * Write the shadow value to the EBU to set the gpios. We need to set the
0039  * global EBU lock to make sure that PCI/MTD don't break.
0040  */
0041 static void ltq_mm_apply(struct ltq_mm *chip)
0042 {
0043     unsigned long flags;
0044
0045     spin_lock_irqsave(&ebu_lock, flags);
0046     ltq_ebu_w32(LTQ_EBU_BUSCON, LTQ_EBU_BUSCON1);
0047     __raw_writew(chip->shadow, chip->mmchip.regs);
0048     ltq_ebu_w32(LTQ_EBU_BUSCON | LTQ_EBU_WP, LTQ_EBU_BUSCON1);
0049     spin_unlock_irqrestore(&ebu_lock, flags);
0050 }
0051
0052 /**
0053  * ltq_mm_set() - gpio_chip->set - set gpios.
0054  * @gc:     Pointer to gpio_chip device structure.
0055  * @gpio:   GPIO signal number.
0056  * @val:    Value to be written to specified signal.
0057  *
0058  * Set the shadow value and call ltq_mm_apply.
0059  */
0060 static void ltq_mm_set(struct gpio_chip *gc, unsigned offset, int value)
0061 {
0062     struct ltq_mm *chip = gpiochip_get_data(gc);
0063
0064     if (value)
0065         chip->shadow |= (1 << offset);
0066     else
0067         chip->shadow &= ~(1 << offset);
0068     ltq_mm_apply(chip);
0069 }
0070
0071 /**
0072  * ltq_mm_dir_out() - gpio_chip->dir_out - set gpio direction.
0073  * @gc:     Pointer to gpio_chip device structure.
0074  * @gpio:   GPIO signal number.
0075  * @val:    Value to be written to specified signal.
0076  *
0077  * Same as ltq_mm_set, always returns 0.
0078  */
0079 static int ltq_mm_dir_out(struct gpio_chip *gc, unsigned offset, int value)
0080 {
0081     ltq_mm_set(gc, offset, value);
0082
0083     return 0;
0084 }
0085
0086 /**
0087  * ltq_mm_save_regs() - Set initial values of GPIO pins
0088  * @mm_gc: pointer to memory mapped GPIO chip structure
0089  */
0090 static void ltq_mm_save_regs(struct of_mm_gpio_chip *mm_gc)
0091 {
0092     struct ltq_mm *chip =
0093         container_of(mm_gc, struct ltq_mm, mmchip);
0094
0095     /* tell the ebu controller which memory address we will be using */
0096     ltq_ebu_w32(CPHYSADDR(chip->mmchip.regs) | 0x1, LTQ_EBU_ADDRSEL1);
0097
0098     ltq_mm_apply(chip);
0099 }
0100
0101 static int ltq_mm_probe(struct platform_device *pdev)
0102 {
0103     struct ltq_mm *chip;
0104     u32 shadow;
0105
0106     chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL);
0107     if (!chip)
0108         return -ENOMEM;
0109
0110     platform_set_drvdata(pdev, chip);
0111
0112     chip->mmchip.gc.ngpio = 16;
0113     chip->mmchip.gc.direction_output = ltq_mm_dir_out;
0114     chip->mmchip.gc.set = ltq_mm_set;
0115     chip->mmchip.save_regs = ltq_mm_save_regs;
0116
0117     /* store the shadow value if one was passed by the devicetree */
0118     if (!of_property_read_u32(pdev->dev.of_node, "lantiq,shadow", &shadow))
0119         chip->shadow = shadow;
0120
0121     return of_mm_gpiochip_add_data(pdev->dev.of_node, &chip->mmchip, chip);
0122 }
0123
0124 static int ltq_mm_remove(struct platform_device *pdev)
0125 {
0126     struct ltq_mm *chip = platform_get_drvdata(pdev);
0127
0128     of_mm_gpiochip_remove(&chip->mmchip);
0129
0130     return 0;
0131 }
0132
0133 static const struct of_device_id ltq_mm_match[] = {
0134     { .compatible = "lantiq,gpio-mm" },
0135     {},
0136 };
0137 MODULE_DEVICE_TABLE(of, ltq_mm_match);
0138
0139 static struct platform_driver ltq_mm_driver = {
0140     .probe = ltq_mm_probe,
0141     .remove = ltq_mm_remove,
0142     .driver = {
0143         .name = "gpio-mm-ltq",
0144         .of_match_table = ltq_mm_match,
0145     },
0146 };
0147
0148 static int __init ltq_mm_init(void)
0149 {
0150     return platform_driver_register(&ltq_mm_driver);
0151 }
0152
0153 subsys_initcall(ltq_mm_init);
0154
0155 static void __exit ltq_mm_exit(void)
0156 {
0157     platform_driver_unregister(&ltq_mm_driver);
0158 }
0159 module_exit(ltq_mm_exit);