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(val: chip->shadow, addr: 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(dev: &pdev->dev, size: sizeof(*chip), GFP_KERNEL); |
107 | if (!chip) |
108 | return -ENOMEM; |
109 | |
110 | platform_set_drvdata(pdev, data: 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(np: pdev->dev.of_node, propname: "lantiq,shadow" , out_value: &shadow)) |
119 | chip->shadow = shadow; |
120 | |
121 | return of_mm_gpiochip_add_data(np: pdev->dev.of_node, mm_gc: &chip->mmchip, data: chip); |
122 | } |
123 | |
124 | static void ltq_mm_remove(struct platform_device *pdev) |
125 | { |
126 | struct ltq_mm *chip = platform_get_drvdata(pdev); |
127 | |
128 | of_mm_gpiochip_remove(mm_gc: &chip->mmchip); |
129 | } |
130 | |
131 | static const struct of_device_id ltq_mm_match[] = { |
132 | { .compatible = "lantiq,gpio-mm" }, |
133 | {}, |
134 | }; |
135 | MODULE_DEVICE_TABLE(of, ltq_mm_match); |
136 | |
137 | static struct platform_driver ltq_mm_driver = { |
138 | .probe = ltq_mm_probe, |
139 | .remove_new = ltq_mm_remove, |
140 | .driver = { |
141 | .name = "gpio-mm-ltq" , |
142 | .of_match_table = ltq_mm_match, |
143 | }, |
144 | }; |
145 | |
146 | static int __init ltq_mm_init(void) |
147 | { |
148 | return platform_driver_register(<q_mm_driver); |
149 | } |
150 | |
151 | subsys_initcall(ltq_mm_init); |
152 | |
153 | static void __exit ltq_mm_exit(void) |
154 | { |
155 | platform_driver_unregister(<q_mm_driver); |
156 | } |
157 | module_exit(ltq_mm_exit); |
158 | |