tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Janz MODULbus VMOD-TTL GPIO Driver
4 *
5 * Copyright (c) 2010 Ira W. Snyder <iws@ovro.caltech.edu>
6 */
7
8#include <linux/kernel.h>
9#include <linux/module.h>
10#include <linux/init.h>
11#include <linux/interrupt.h>
12#include <linux/delay.h>
13#include <linux/platform_device.h>
14#include <linux/io.h>
15#include <linux/gpio/driver.h>
16#include <linux/slab.h>
17#include <linux/bitops.h>
18
19#include <linux/mfd/janz.h>
20
21#define DRV_NAME "janz-ttl"
22
23#define PORTA_DIRECTION 0x23
24#define PORTB_DIRECTION 0x2B
25#define PORTC_DIRECTION 0x06
26#define PORTA_IOCTL 0x24
27#define PORTB_IOCTL 0x2C
28#define PORTC_IOCTL 0x07
29
30#define MASTER_INT_CTL 0x00
31#define MASTER_CONF_CTL 0x01
32
33#define CONF_PAE BIT(2)
34#define CONF_PBE BIT(7)
35#define CONF_PCE BIT(4)
36
37struct ttl_control_regs {
38 __be16 portc;
39 __be16 portb;
40 __be16 porta;
41 __be16 control;
42};
43
44struct ttl_module {
45 struct gpio_chip gpio;
46
47 /* base address of registers */
48 struct ttl_control_regs __iomem *regs;
49
50 u8 portc_shadow;
51 u8 portb_shadow;
52 u8 porta_shadow;
53
54 spinlock_t lock;
55};
56
57static int ttl_get_value(struct gpio_chip *gpio, unsigned offset)
58{
59 struct ttl_module *mod = dev_get_drvdata(gpio->parent);
60 u8 *shadow;
61 int ret;
62
63 if (offset < 8) {
64 shadow = &mod->porta_shadow;
65 } else if (offset < 16) {
66 shadow = &mod->portb_shadow;
67 offset -= 8;
68 } else {
69 shadow = &mod->portc_shadow;
70 offset -= 16;
71 }
72
73 spin_lock(&mod->lock);
74 ret = *shadow & BIT(offset);
75 spin_unlock(&mod->lock);
76 return !!ret;
77}
78
79static int ttl_set_value(struct gpio_chip *gpio, unsigned int offset, int value)
80{
81 struct ttl_module *mod = dev_get_drvdata(gpio->parent);
82 void __iomem *port;
83 u8 *shadow;
84
85 if (offset < 8) {
86 port = &mod->regs->porta;
87 shadow = &mod->porta_shadow;
88 } else if (offset < 16) {
89 port = &mod->regs->portb;
90 shadow = &mod->portb_shadow;
91 offset -= 8;
92 } else {
93 port = &mod->regs->portc;
94 shadow = &mod->portc_shadow;
95 offset -= 16;
96 }
97
98 spin_lock(&mod->lock);
99 if (value)
100 *shadow |= BIT(offset);
101 else
102 *shadow &= ~BIT(offset);
103
104 iowrite16be(*shadow, port);
105 spin_unlock(&mod->lock);
106
107 return 0;
108}
109
110static void ttl_write_reg(struct ttl_module *mod, u8 reg, u16 val)
111{
112 iowrite16be(reg, &mod->regs->control);
113 iowrite16be(val, &mod->regs->control);
114}
115
116static void ttl_setup_device(struct ttl_module *mod)
117{
118 /* reset the device to a known state */
119 iowrite16be(0x0000, &mod->regs->control);
120 iowrite16be(0x0001, &mod->regs->control);
121 iowrite16be(0x0000, &mod->regs->control);
122
123 /* put all ports in open-drain mode */
124 ttl_write_reg(mod, PORTA_IOCTL, 0x00ff);
125 ttl_write_reg(mod, PORTB_IOCTL, 0x00ff);
126 ttl_write_reg(mod, PORTC_IOCTL, 0x000f);
127
128 /* set all ports as outputs */
129 ttl_write_reg(mod, PORTA_DIRECTION, 0x0000);
130 ttl_write_reg(mod, PORTB_DIRECTION, 0x0000);
131 ttl_write_reg(mod, PORTC_DIRECTION, 0x0000);
132
133 /* set all ports to drive zeroes */
134 iowrite16be(0x0000, &mod->regs->porta);
135 iowrite16be(0x0000, &mod->regs->portb);
136 iowrite16be(0x0000, &mod->regs->portc);
137
138 /* enable all ports */
139 ttl_write_reg(mod, MASTER_CONF_CTL, CONF_PAE | CONF_PBE | CONF_PCE);
140}
141
142static int ttl_probe(struct platform_device *pdev)
143{
144 struct janz_platform_data *pdata;
145 struct ttl_module *mod;
146 struct gpio_chip *gpio;
147 int ret;
148
149 pdata = dev_get_platdata(&pdev->dev);
150 if (!pdata) {
151 dev_err(&pdev->dev, "no platform data\n");
152 return -ENXIO;
153 }
154
155 mod = devm_kzalloc(&pdev->dev, sizeof(*mod), GFP_KERNEL);
156 if (!mod)
157 return -ENOMEM;
158
159 platform_set_drvdata(pdev, mod);
160 spin_lock_init(&mod->lock);
161
162 /* get access to the MODULbus registers for this module */
163 mod->regs = devm_platform_ioremap_resource(pdev, 0);
164 if (IS_ERR(mod->regs))
165 return PTR_ERR(mod->regs);
166
167 ttl_setup_device(mod);
168
169 /* Initialize the GPIO data structures */
170 gpio = &mod->gpio;
171 gpio->parent = &pdev->dev;
172 gpio->label = pdev->name;
173 gpio->get = ttl_get_value;
174 gpio->set = ttl_set_value;
175 gpio->owner = THIS_MODULE;
176
177 /* request dynamic allocation */
178 gpio->base = -1;
179 gpio->ngpio = 20;
180
181 ret = devm_gpiochip_add_data(&pdev->dev, gpio, NULL);
182 if (ret) {
183 dev_err(&pdev->dev, "unable to add GPIO chip\n");
184 return ret;
185 }
186
187 return 0;
188}
189
190static struct platform_driver ttl_driver = {
191 .driver = {
192 .name = DRV_NAME,
193 },
194 .probe = ttl_probe,
195};
196
197module_platform_driver(ttl_driver);
198
199MODULE_AUTHOR("Ira W. Snyder <iws@ovro.caltech.edu>");
200MODULE_DESCRIPTION("Janz MODULbus VMOD-TTL Driver");
201MODULE_LICENSE("GPL");
202MODULE_ALIAS("platform:janz-ttl");