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 */
ltq_mm_apply(struct ltq_mm * chip)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 */
ltq_mm_set(struct gpio_chip * gc,unsigned offset,int value)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 */
ltq_mm_dir_out(struct gpio_chip * gc,unsigned offset,int value)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 */
ltq_mm_save_regs(struct of_mm_gpio_chip * mm_gc)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
ltq_mm_probe(struct platform_device * pdev)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
ltq_mm_remove(struct platform_device * pdev)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
ltq_mm_init(void)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
ltq_mm_exit(void)155 static void __exit ltq_mm_exit(void)
156 {
157 platform_driver_unregister(<q_mm_driver);
158 }
159 module_exit(ltq_mm_exit);
160