tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/*
2 * Janz MODULbus VMOD-TTL GPIO Driver
3 *
4 * Copyright (c) 2010 Ira W. Snyder <iws@ovro.caltech.edu>
5 *
6 * This program is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License as published by the
8 * Free Software Foundation; either version 2 of the License, or (at your
9 * option) any later version.
10 */
11
12#include <linux/kernel.h>
13#include <linux/module.h>
14#include <linux/init.h>
15#include <linux/interrupt.h>
16#include <linux/delay.h>
17#include <linux/platform_device.h>
18#include <linux/io.h>
19#include <linux/gpio/driver.h>
20#include <linux/slab.h>
21#include <linux/bitops.h>
22
23#include <linux/mfd/janz.h>
24
25#define DRV_NAME "janz-ttl"
26
27#define PORTA_DIRECTION 0x23
28#define PORTB_DIRECTION 0x2B
29#define PORTC_DIRECTION 0x06
30#define PORTA_IOCTL 0x24
31#define PORTB_IOCTL 0x2C
32#define PORTC_IOCTL 0x07
33
34#define MASTER_INT_CTL 0x00
35#define MASTER_CONF_CTL 0x01
36
37#define CONF_PAE BIT(2)
38#define CONF_PBE BIT(7)
39#define CONF_PCE BIT(4)
40
41struct ttl_control_regs {
42 __be16 portc;
43 __be16 portb;
44 __be16 porta;
45 __be16 control;
46};
47
48struct ttl_module {
49 struct gpio_chip gpio;
50
51 /* base address of registers */
52 struct ttl_control_regs __iomem *regs;
53
54 u8 portc_shadow;
55 u8 portb_shadow;
56 u8 porta_shadow;
57
58 spinlock_t lock;
59};
60
61static int ttl_get_value(struct gpio_chip *gpio, unsigned offset)
62{
63 struct ttl_module *mod = dev_get_drvdata(gpio->parent);
64 u8 *shadow;
65 int ret;
66
67 if (offset < 8) {
68 shadow = &mod->porta_shadow;
69 } else if (offset < 16) {
70 shadow = &mod->portb_shadow;
71 offset -= 8;
72 } else {
73 shadow = &mod->portc_shadow;
74 offset -= 16;
75 }
76
77 spin_lock(&mod->lock);
78 ret = *shadow & BIT(offset);
79 spin_unlock(&mod->lock);
80 return !!ret;
81}
82
83static void ttl_set_value(struct gpio_chip *gpio, unsigned offset, int value)
84{
85 struct ttl_module *mod = dev_get_drvdata(gpio->parent);
86 void __iomem *port;
87 u8 *shadow;
88
89 if (offset < 8) {
90 port = &mod->regs->porta;
91 shadow = &mod->porta_shadow;
92 } else if (offset < 16) {
93 port = &mod->regs->portb;
94 shadow = &mod->portb_shadow;
95 offset -= 8;
96 } else {
97 port = &mod->regs->portc;
98 shadow = &mod->portc_shadow;
99 offset -= 16;
100 }
101
102 spin_lock(&mod->lock);
103 if (value)
104 *shadow |= BIT(offset);
105 else
106 *shadow &= ~BIT(offset);
107
108 iowrite16be(*shadow, port);
109 spin_unlock(&mod->lock);
110}
111
112static void ttl_write_reg(struct ttl_module *mod, u8 reg, u16 val)
113{
114 iowrite16be(reg, &mod->regs->control);
115 iowrite16be(val, &mod->regs->control);
116}
117
118static void ttl_setup_device(struct ttl_module *mod)
119{
120 /* reset the device to a known state */
121 iowrite16be(0x0000, &mod->regs->control);
122 iowrite16be(0x0001, &mod->regs->control);
123 iowrite16be(0x0000, &mod->regs->control);
124
125 /* put all ports in open-drain mode */
126 ttl_write_reg(mod, PORTA_IOCTL, 0x00ff);
127 ttl_write_reg(mod, PORTB_IOCTL, 0x00ff);
128 ttl_write_reg(mod, PORTC_IOCTL, 0x000f);
129
130 /* set all ports as outputs */
131 ttl_write_reg(mod, PORTA_DIRECTION, 0x0000);
132 ttl_write_reg(mod, PORTB_DIRECTION, 0x0000);
133 ttl_write_reg(mod, PORTC_DIRECTION, 0x0000);
134
135 /* set all ports to drive zeroes */
136 iowrite16be(0x0000, &mod->regs->porta);
137 iowrite16be(0x0000, &mod->regs->portb);
138 iowrite16be(0x0000, &mod->regs->portc);
139
140 /* enable all ports */
141 ttl_write_reg(mod, MASTER_CONF_CTL, CONF_PAE | CONF_PBE | CONF_PCE);
142}
143
144static int ttl_probe(struct platform_device *pdev)
145{
146 struct janz_platform_data *pdata;
147 struct device *dev = &pdev->dev;
148 struct ttl_module *mod;
149 struct gpio_chip *gpio;
150 int ret;
151
152 pdata = dev_get_platdata(&pdev->dev);
153 if (!pdata) {
154 dev_err(dev, "no platform data\n");
155 return -ENXIO;
156 }
157
158 mod = devm_kzalloc(dev, sizeof(*mod), GFP_KERNEL);
159 if (!mod)
160 return -ENOMEM;
161
162 platform_set_drvdata(pdev, mod);
163 spin_lock_init(&mod->lock);
164
165 /* get access to the MODULbus registers for this module */
166 mod->regs = devm_platform_ioremap_resource(pdev, 0);
167 if (IS_ERR(mod->regs))
168 return PTR_ERR(mod->regs);
169
170 ttl_setup_device(mod);
171
172 /* Initialize the GPIO data structures */
173 gpio = &mod->gpio;
174 gpio->parent = &pdev->dev;
175 gpio->label = pdev->name;
176 gpio->get = ttl_get_value;
177 gpio->set = ttl_set_value;
178 gpio->owner = THIS_MODULE;
179
180 /* request dynamic allocation */
181 gpio->base = -1;
182 gpio->ngpio = 20;
183
184 ret = devm_gpiochip_add_data(dev, gpio, NULL);
185 if (ret) {
186 dev_err(dev, "unable to add GPIO chip\n");
187 return ret;
188 }
189
190 return 0;
191}
192
193static struct platform_driver ttl_driver = {
194 .driver = {
195 .name = DRV_NAME,
196 },
197 .probe = ttl_probe,
198};
199
200module_platform_driver(ttl_driver);
201
202MODULE_AUTHOR("Ira W. Snyder <iws@ovro.caltech.edu>");
203MODULE_DESCRIPTION("Janz MODULbus VMOD-TTL Driver");
204MODULE_LICENSE("GPL");
205MODULE_ALIAS("platform:janz-ttl");