1 /* 2 * This program is free software; you can redistribute it and/or modify it 3 * under the terms of the GNU General Public License version 2 as published 4 * by the Free Software Foundation. 5 * 6 * Copyright (C) 2012 John Crispin <john@phrozen.org> 7 */ 8 9 #include <linux/init.h> 10 #include <linux/module.h> 11 #include <linux/types.h> 12 #include <linux/platform_device.h> 13 #include <linux/mutex.h> 14 #include <linux/gpio/driver.h> 15 #include <linux/of.h> 16 #include <linux/of_gpio.h> 17 #include <linux/io.h> 18 #include <linux/slab.h> 19 20 #include <lantiq_soc.h> 21 22 /* 23 * By attaching hardware latches to the EBU it is possible to create output 24 * only gpios. This driver configures a special memory address, which when 25 * written to outputs 16 bit to the latches. 26 */ 27 28 #define LTQ_EBU_BUSCON 0x1e7ff /* 16 bit access, slowest timing */ 29 #define LTQ_EBU_WP 0x80000000 /* write protect bit */ 30 31 struct ltq_mm { 32 struct of_mm_gpio_chip mmchip; 33 u16 shadow; /* shadow the latches state */ 34 }; 35 36 /** 37 * ltq_mm_apply() - write the shadow value to the ebu address. 38 * @chip: Pointer to our private data structure. 39 * 40 * Write the shadow value to the EBU to set the gpios. We need to set the 41 * global EBU lock to make sure that PCI/MTD dont break. 42 */ 43 static void ltq_mm_apply(struct ltq_mm *chip) 44 { 45 unsigned long flags; 46 47 spin_lock_irqsave(&ebu_lock, flags); 48 ltq_ebu_w32(LTQ_EBU_BUSCON, LTQ_EBU_BUSCON1); 49 __raw_writew(chip->shadow, chip->mmchip.regs); 50 ltq_ebu_w32(LTQ_EBU_BUSCON | LTQ_EBU_WP, LTQ_EBU_BUSCON1); 51 spin_unlock_irqrestore(&ebu_lock, flags); 52 } 53 54 /** 55 * ltq_mm_set() - gpio_chip->set - set gpios. 56 * @gc: Pointer to gpio_chip device structure. 57 * @gpio: GPIO signal number. 58 * @val: Value to be written to specified signal. 59 * 60 * Set the shadow value and call ltq_mm_apply. 61 */ 62 static void ltq_mm_set(struct gpio_chip *gc, unsigned offset, int value) 63 { 64 struct ltq_mm *chip = gpiochip_get_data(gc); 65 66 if (value) 67 chip->shadow |= (1 << offset); 68 else 69 chip->shadow &= ~(1 << offset); 70 ltq_mm_apply(chip); 71 } 72 73 /** 74 * ltq_mm_dir_out() - gpio_chip->dir_out - set gpio direction. 75 * @gc: Pointer to gpio_chip device structure. 76 * @gpio: GPIO signal number. 77 * @val: Value to be written to specified signal. 78 * 79 * Same as ltq_mm_set, always returns 0. 80 */ 81 static int ltq_mm_dir_out(struct gpio_chip *gc, unsigned offset, int value) 82 { 83 ltq_mm_set(gc, offset, value); 84 85 return 0; 86 } 87 88 /** 89 * ltq_mm_save_regs() - Set initial values of GPIO pins 90 * @mm_gc: pointer to memory mapped GPIO chip structure 91 */ 92 static void ltq_mm_save_regs(struct of_mm_gpio_chip *mm_gc) 93 { 94 struct ltq_mm *chip = 95 container_of(mm_gc, struct ltq_mm, mmchip); 96 97 /* tell the ebu controller which memory address we will be using */ 98 ltq_ebu_w32(CPHYSADDR(chip->mmchip.regs) | 0x1, LTQ_EBU_ADDRSEL1); 99 100 ltq_mm_apply(chip); 101 } 102 103 static int ltq_mm_probe(struct platform_device *pdev) 104 { 105 struct ltq_mm *chip; 106 u32 shadow; 107 108 chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL); 109 if (!chip) 110 return -ENOMEM; 111 112 platform_set_drvdata(pdev, chip); 113 114 chip->mmchip.gc.ngpio = 16; 115 chip->mmchip.gc.direction_output = ltq_mm_dir_out; 116 chip->mmchip.gc.set = ltq_mm_set; 117 chip->mmchip.save_regs = ltq_mm_save_regs; 118 119 /* store the shadow value if one was passed by the devicetree */ 120 if (!of_property_read_u32(pdev->dev.of_node, "lantiq,shadow", &shadow)) 121 chip->shadow = shadow; 122 123 return of_mm_gpiochip_add_data(pdev->dev.of_node, &chip->mmchip, chip); 124 } 125 126 static int ltq_mm_remove(struct platform_device *pdev) 127 { 128 struct ltq_mm *chip = platform_get_drvdata(pdev); 129 130 of_mm_gpiochip_remove(&chip->mmchip); 131 132 return 0; 133 } 134 135 static const struct of_device_id ltq_mm_match[] = { 136 { .compatible = "lantiq,gpio-mm" }, 137 {}, 138 }; 139 MODULE_DEVICE_TABLE(of, ltq_mm_match); 140 141 static struct platform_driver ltq_mm_driver = { 142 .probe = ltq_mm_probe, 143 .remove = ltq_mm_remove, 144 .driver = { 145 .name = "gpio-mm-ltq", 146 .of_match_table = ltq_mm_match, 147 }, 148 }; 149 150 static int __init ltq_mm_init(void) 151 { 152 return platform_driver_register(<q_mm_driver); 153 } 154 155 subsys_initcall(ltq_mm_init); 156 157 static void __exit ltq_mm_exit(void) 158 { 159 platform_driver_unregister(<q_mm_driver); 160 } 161 module_exit(ltq_mm_exit); 162