1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * 4 * Copyright (C) 2012 John Crispin <john@phrozen.org> 5 */ 6 7 #include <linux/init.h> 8 #include <linux/module.h> 9 #include <linux/types.h> 10 #include <linux/platform_device.h> 11 #include <linux/mutex.h> 12 #include <linux/gpio/driver.h> 13 #include <linux/gpio/legacy-of-mm-gpiochip.h> 14 #include <linux/of.h> 15 #include <linux/io.h> 16 #include <linux/slab.h> 17 18 #include <lantiq_soc.h> 19 20 /* 21 * By attaching hardware latches to the EBU it is possible to create output 22 * only gpios. This driver configures a special memory address, which when 23 * written to outputs 16 bit to the latches. 24 */ 25 26 #define LTQ_EBU_BUSCON 0x1e7ff /* 16 bit access, slowest timing */ 27 #define LTQ_EBU_WP 0x80000000 /* write protect bit */ 28 29 struct ltq_mm { 30 struct of_mm_gpio_chip mmchip; 31 u16 shadow; /* shadow the latches state */ 32 }; 33 34 /** 35 * ltq_mm_apply() - write the shadow value to the ebu address. 36 * @chip: Pointer to our private data structure. 37 * 38 * Write the shadow value to the EBU to set the gpios. We need to set the 39 * global EBU lock to make sure that PCI/MTD don't break. 40 */ 41 static void ltq_mm_apply(struct ltq_mm *chip) 42 { 43 unsigned long flags; 44 45 spin_lock_irqsave(&ebu_lock, flags); 46 ltq_ebu_w32(LTQ_EBU_BUSCON, LTQ_EBU_BUSCON1); 47 __raw_writew(chip->shadow, chip->mmchip.regs); 48 ltq_ebu_w32(LTQ_EBU_BUSCON | LTQ_EBU_WP, LTQ_EBU_BUSCON1); 49 spin_unlock_irqrestore(&ebu_lock, flags); 50 } 51 52 /** 53 * ltq_mm_set() - gpio_chip->set - set gpios. 54 * @gc: Pointer to gpio_chip device structure. 55 * @gpio: GPIO signal number. 56 * @val: Value to be written to specified signal. 57 * 58 * Set the shadow value and call ltq_mm_apply. 59 */ 60 static void ltq_mm_set(struct gpio_chip *gc, unsigned offset, int value) 61 { 62 struct ltq_mm *chip = gpiochip_get_data(gc); 63 64 if (value) 65 chip->shadow |= (1 << offset); 66 else 67 chip->shadow &= ~(1 << offset); 68 ltq_mm_apply(chip); 69 } 70 71 /** 72 * ltq_mm_dir_out() - gpio_chip->dir_out - set gpio direction. 73 * @gc: Pointer to gpio_chip device structure. 74 * @gpio: GPIO signal number. 75 * @val: Value to be written to specified signal. 76 * 77 * Same as ltq_mm_set, always returns 0. 78 */ 79 static int ltq_mm_dir_out(struct gpio_chip *gc, unsigned offset, int value) 80 { 81 ltq_mm_set(gc, offset, value); 82 83 return 0; 84 } 85 86 /** 87 * ltq_mm_save_regs() - Set initial values of GPIO pins 88 * @mm_gc: pointer to memory mapped GPIO chip structure 89 */ 90 static void ltq_mm_save_regs(struct of_mm_gpio_chip *mm_gc) 91 { 92 struct ltq_mm *chip = 93 container_of(mm_gc, struct ltq_mm, mmchip); 94 95 /* tell the ebu controller which memory address we will be using */ 96 ltq_ebu_w32(CPHYSADDR(chip->mmchip.regs) | 0x1, LTQ_EBU_ADDRSEL1); 97 98 ltq_mm_apply(chip); 99 } 100 101 static int ltq_mm_probe(struct platform_device *pdev) 102 { 103 struct ltq_mm *chip; 104 u32 shadow; 105 106 chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL); 107 if (!chip) 108 return -ENOMEM; 109 110 platform_set_drvdata(pdev, chip); 111 112 chip->mmchip.gc.ngpio = 16; 113 chip->mmchip.gc.direction_output = ltq_mm_dir_out; 114 chip->mmchip.gc.set = ltq_mm_set; 115 chip->mmchip.save_regs = ltq_mm_save_regs; 116 117 /* store the shadow value if one was passed by the devicetree */ 118 if (!of_property_read_u32(pdev->dev.of_node, "lantiq,shadow", &shadow)) 119 chip->shadow = shadow; 120 121 return of_mm_gpiochip_add_data(pdev->dev.of_node, &chip->mmchip, chip); 122 } 123 124 static int ltq_mm_remove(struct platform_device *pdev) 125 { 126 struct ltq_mm *chip = platform_get_drvdata(pdev); 127 128 of_mm_gpiochip_remove(&chip->mmchip); 129 130 return 0; 131 } 132 133 static const struct of_device_id ltq_mm_match[] = { 134 { .compatible = "lantiq,gpio-mm" }, 135 {}, 136 }; 137 MODULE_DEVICE_TABLE(of, ltq_mm_match); 138 139 static struct platform_driver ltq_mm_driver = { 140 .probe = ltq_mm_probe, 141 .remove = ltq_mm_remove, 142 .driver = { 143 .name = "gpio-mm-ltq", 144 .of_match_table = ltq_mm_match, 145 }, 146 }; 147 148 static int __init ltq_mm_init(void) 149 { 150 return platform_driver_register(<q_mm_driver); 151 } 152 153 subsys_initcall(ltq_mm_init); 154 155 static void __exit ltq_mm_exit(void) 156 { 157 platform_driver_unregister(<q_mm_driver); 158 } 159 module_exit(ltq_mm_exit); 160